TWISTED-ALIGNMENT-MODE LIQUID CRYSTAL DISPLAY BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a twisted-alignment-mode liquid crystal display. BACKGROUND ART A twisted alignment mode such as a twisted nematic (TN) mode is generally used as a drive mode of a liquid crystal display, in which an electric field is applied between upper and lower substrates to induce rising of liquid crystal molecules for driving the liquid crystal display. A TN-mode liquid crystal display includes, for example, a cellulose acetate film as a protective film to protect a polarizer. The total thickness of a liquid crystal display is recently required to be reduced in response to a strong demand for a thinner display. This results in a decrease in a distance between a liquid crystal panel unit and a backlight unit, causing distortion of an optical film due to heat from a backlight. As a result, retardation occurs at ends of a liquid crystal display, leading to frame-like light leakage during black display. In a proposed means to solve the above-described problem, a photoelastic coefficient of an adhesive layer, which is used for preparing a polarizing plate, is adjusted within a predetermined range, for example, as disclosed in JP-A-2006-91254 and JP-A-2006-208465. In another proposed means, cellulose acylate having a low degree of substitution of acyl groups is used as a material for a protective film of a polarizing plate used in a liquid crystal display, for example, as disclosed in JP-A-2009-265598. SUMMARY OF THE INVENTION An object of the present invention, which has been made in light of the problem, is to reduce frame-like light leakage during black display by a twisted-alignment-mode liquid crystal display. Means for solving the above-described problem are as follows: [1] A twisted-alignment-mode liquid crystal display comprising: a pair of polarizers disposed such that the polarization axes are orthogonal to each other; a twisted-alignment-mode liquid crystal cell disposed between the polarizers; and a low-substitution layer comprising cellulose acylate satisfying Formula (1) as a main component, (1) 2.CKZK2.7, where Zl represents the total degree of substitution of acyl groups of the cellulose acylate in the low-substitution layer. [2] The liquid crystal display according to [1], wherein the low-substitution layers are each disposed between the pair of polarizers and the twisted-alignment-mode liquid crystal cell. [3] The liquid crystal display according to [2], wherein the low-substitution layer has a retardation in-plane Re (550) of -50 to 150 nm and a retardation along the thickness direction Rth (550) of -50 to 200 nm at a wavelength of 550 nm. [4] The liquid crystal display according to any one of [1] to [3], wherein the low-substitution layers are each provided on an outer surface of each of the pair of polarizers. [5] The liquid crystal display according to [1], wherein the low-substitution layers are each disposed on an outer surface of each of the pair of polarizers, and are not disposed between each of the pair of polarizers and the twisted-alignment-mode liquid crystal cell, and the liquid crystal display comprises optically anisotropic layers between each of the pair of polarizers and the twisted-alignment-mode liquid crystal cell, the optically anisotropic layers comprising liquid crystal compounds which are fixed to be in a state of hybrid alignment. [6] The liquid crystal display according to any one of [1] to [5], wherein the low-substitution layer has a thickness of 30 to 80 jam. [7] The liquid crystal display according to any one of [1] to [6], wherein the low-substitution layer further comprises a non-phosphate ester compound. [8] The liquid crystal display according to any one of [1] to [7] , which comprises a high-substitution layer disposed on at least one surface of the low-substitution layers, and the high-substitution layer comprising cellulose acylate satisfying Formula (2) as a main component, (2) 2.7 At least one additive other than the non-phosphate ester compound may be added to the low-substitution layer and high-substitution layer, and examples of the additive include retardation controllers (e.g. retardation enhancers and retardation reducers), plasticizers such as phthalates and phosphates, UV absorbers, antioxidants and matting agents. According to the invention, the retardation reducer may be selected from any phosphoric acid type ester compounds or any known additives as an additive for a cellulose acylate film other than the non-phosphate ester compound. The polymer retardation reducer is preferably selected from phosphate-polyester type polymers, styrene-type polymers, acryl-type polymers and any combinations thereof, and more preferably selected from acryl-type polymers and styrene-type polymers. At least one of the polymer retardation reducer is preferably selected from negative intrinsic birefringent polymers such as styrene-type and acryl-type polymers. Examples of the compound other than the non-phosphate ester compound which can be used as the low-molecular weight retardation reducer include, but are not limited to, those described below. The low-molecular weight retardation reducer may be selected from solid or oily compounds. Namely, the low-molecular weight retardation reducer to be used in the invention is not limited in terms of the melting or boiling point. The mixture of UV absorbers having the melting point of not greater than 20 degrees Celsius and greater than 20 degrees Celsius respectively may be used, as well as the mixture of anti-degradation agents. Examples of the infrared absorber dye include those described in JP-A-2001-194522. The additive may be added to a cellulose acylate solution (dope) anytime in preparing the solution. Adding the additive to the cellulose acylate solution may be carried out as the final step in the preparation of the solution. An amount of each additive is not limited so far as obtaining its function. Examples of the low-molecular weight retardation reducer other than non-phosphate ester compound include, but are not limited, those described in JP-A-2007-272177, [0066]- [0085]. The compounds, which are described in JP-A-2007-272177, [0066]-[0085] , may be prepared according to the method described below. The compound represented by formula (1) described in JP-A-2007-272177 may be prepared by a condensation reaction of a sulfonyl chloride derivative and an amine derivative. The compound represented . by formula (2) described in JP-A-2007-272177 may be prepared by a dehydration-condensation reaction of a carboxylic acid and an amine using a condensation agent such as dicyclohexylcarbodiimide (DCC) , or by a substitution reaction of a carbonyl chloride derivative and an amine derivative. Examples of the retardation reducer include Rth reducers. Among the above-described retardation reducers, acryl-type polymers, styrene-type polymers, and low-molecular weight compounds of formulas (3) - (7) , described in JP-A-2007-272177, can be used as an Rth reducer. Among these, acryl-type and styrene-type polymers are preferable, and acryl-type polymers are more preferable. An amount of the retardation reducer with respect to the cellulose acylate is preferably from 0.01 to 30% by mass, more preferably from 0.1 to 20% by mass, or even more preferably from 0.1 to 10% by mass. When the amount is not greater than 30% by mass, it is possible to improve the compatibility with the cellulose acylate and to prevent from getting cloudy. When plural retardation reducers are used, a total amount thereof preferably falls within the above-described range. (Plasticizer) Any compounds which have been known as a plasticizer in cellulose acylate may be used in the invention. Examples of the plasticizer include phosphate esters and carboxylate esters. Examples of the phosphates include triphenyl phosphate' (TPP) and tricresyl phosphate (TCP) . The carboxylates are typically phthalates and citrates. Examples of the phthalates include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP) , diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of the citrates include triethyl O-acetyl citrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylates include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, various trimellitates, etc. The phthalate-type plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used here. DEP and DPP are especially preferred. (Retardation Developer) The low-substitution cellulose acylate film preferably contains at least one retardation developer in the low-substitution layer in order to develop a retardation value. Examples of the retardation developer include, but not limited to, rod or disc compounds, and compounds having a retardation developing function among the above-described non-phosphorylated ester compounds. In the rod or discotic compounds, a compound having at least two aromatic rings can be preferably used as the retardation developer. The proportion of the retardation developer composed of the rod compound is preferably 0.1 to 30 parts by mass, and more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of a polymer component containing the cellulose acylate. The content of the disc compound in the retardation developer is preferably less than 3 parts by mass, more preferably less than 2 parts by mass, and most preferably less than 1 part by mass with respect to 100 parts by mass of the cellulose acylate. The discotic compound has an excellent Rth retardation developing function compared with the rod compound, and is preferably used if a particularly large Rth retardation is required. Two or more retardation developers may be used in combination. The retardation developer preferably has maximal absorption in a wavelength range of 250 to 400 nm while having substantially no absorption in a visible region. The discotic compound is now described. A compound having at least two aromatic rings can be used as the discotic compound. In this specification, "aromatic ring" includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring. The aromatic hydrocarbon ring is preferably six-membered rings (benzene rings). The aromatic hetero ring is commonly an unsaturated hetero ring. The aromatic hetero ring is preferably a five-, six-, or seven-membered ring, and more preferably a five- or six-membered ring. The aromatic hetero ring commonly has its maximum double bonds. Preferred heteroatoms include nitrogen, oxygen, and sulfur atoms, among which a nitrogen atom is particularly preferred. Examples of the aromatic hetero ring include a furan ring, a thiophene ring, a pyrrole ring, oxazole rings, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, a furazan ring, a triazole ring, a pyran ring, a pyridine, ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, and a 1,3,5-triazine ring. Preferred aromatic ring includes a benzene ring, a condensed benzene ring, and biphenyls. In particular, 1, 3,5-triazine ring is preferably used. Specifically, for example, the compounds disclosed in JP-A-2001-166144 are preferably used. The number of carbon atoms of the aromatic rings of the retardation developer ranges preferably from 2 to 20, more preferably from 2 to 12, further preferably from 2 to 8, and most preferably from 2 to 6. A bonding state between the two aromatic rings includes (a) formation of a condensed ring, (b) direct bonding through a single bond, and (c) bonding through a linking group (spiro linkage is not allowed due to the aromatic rings) . The two aromatic rings may be bonded together through any of the bonding modes (a) to (c). Examples of the condensed ring (a) (a condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, a pyrene ring, an indole ring, an isoindole ring, a benzofuran ring, a benzothiophene ring, an indolizine ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, a benzotriazole ring, a purine ring, an indazole ring, a chromene ring, a quinoline ring, an isoquinoline ring, a quinolizine ring, a quinazoline ring, a cinnoline ring, a quinoxaline ring, a phthalazine ring, a pteridine ring, a carbazole ring, an acridine ring, a phenanthridine ring, a xanthene ring, a phenazine ring, a phenothiazine ring, a phenoxathiin ring, a phenoxazine ring, and a thianthrene ring. In particular, the naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, and quinoline ring are preferred. The single bond (b) is preferably a bond between the carbon atoms of two aromatic rings. Two aromatic rings may be bonded through two or more single bonds to form an aliphatic ring or a nonaromatic heterocycle between the two aromatic rings. The linking group (c) is also preferably bonded to the carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, -CO-, -0-, -NH-, -S-, or a combination thereof. Examples of the linking group combination are shown below. In the exemplary linking group combination, the order of the linking groups may be reversed. cl: -C0-0- c2: -CO-NH- c3: -alkylene-O- c4: -NH-CO-NH- c5: -NH-CO-0- c6: -0-C0-0- c7: -O-alkylene-0- c8: -CO-alkenylene- c9: -CO-alkenylene-NH- c10: -CO-alkenylene-O- c11: -alkylene-CO-O-alkylene-O-CO-alkylene- cl2: -O-alkylene-CO-O-alkylene-O-CO-alkylene-O- cl3: -O-CO-alkylene-CO-O- cl4: -NH-CO-alkenylene- cl5: -O-CO-alkylene- The aromatic ring and the linking group may each have a substituent. Examples of the substituent include halogen atoms (F, CI, Br, and I), a hydroxyl group, a carboxyl group, a cyano group, an amino group, a nitro group, a sulfo group, a carbamoyl group, a sulfamoyl group, an ureido group, an alkyl group, an alkenyl group, an alkynyl group, an aliphatic acyl group, an aliphatic acyloxy group, an alkoxy group,-, an alkoxycarbonyl group, an alkoxycarbonylamino group, an alkylthio group, an alkylsulfonyl group, an aliphatic amide group, an aliphatic sulfonamide group, an aliphatic substituted amino group, an aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group, and a nonaromatic heterocyclic group. The alkyl group preferably has 1 to 8 carbon atoms. A chain allyl group is preferred compared with a cyclic allyl group, and a linear chain alkyl group is particularly preferred. The alkyl group may further have a substituent, for example, a hydroxy group, a carboxy group, an alkoxy group, and an alkyl-substituted amino group. Examples of the alkyl group (including a substituted alkyl group) include a methyl group, an ethyl group, an n-butyl group, an n-hexyl group, 2-hydroxyethyl group, 4-carbxybutyl group, 2-methoxyethyl group, and 2-diethylaminoethyl group. The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferred compared with a cyclic alkenyl group, and a linear chain alkenyl group is particularly preferred. The alkenyl group may further have a substituent. Examples of the alkenyl groups include a vinyl group, an allyl group, and a 1-hexenyl group. The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferred compared with a cyclic alkynyl group, and a linear chain alkynyl group is particularly preferred. The alkynyl group may further have a substituent. Examples of the alkynyl group include an ethynyl group, a 1-butynyl group, and a 1-hexynyl group. The aliphatic acyl group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group. The aliphatic acyloxy group preferably has 1 to 10 carbon atoms . Examples of the aliphatic acyloxy group include an acetoxy group. The alkoxy group preferably has 1 to 8 carbon atoms . The alkoxy group may further have a substituent (for example, an alkoxy group). Examples of the alkoxy group (including substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group. The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl groups include a methoxycarbonyl group and an ethoxycarbonyl group. The alkoxycarbonylamino group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonylamino groups include a methoxycarbonylamino group and an ethoxycarbonylamino group. The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group. The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl groups include a methanesulfonyl group and an ethanesulfonyl group. The aliphatic amide group preferably has 1 to 10 carbon atoms. Examples of the aliphatic amide group include acetamide. The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamide group include a methanesulfonamide group, a butanesulfonamide group, and an n-octanesulfonamide group. The aliphatic substituted amino group preferably has 1 to 10 carbon atoms. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group. The aliphatic substituted carbamoyl group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group. The aliphatic substituted sulfamoyl group preferably has 1 to 8 carbon atoms. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group. The aliphatic substituted ureido group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted ureido group include a methylureido group. Examples of the nonaromatic heterocyclic group include a piperidino group and a morpholino group. The molecular weight of the retardation developer preferably ranges from 300 to 800. A triazine compound represented by formula (I) is preferably used as a discotic compound. Formula (I) In formula (I), R201's each independently represent an aromatic ring or a heterocycle having at least one substituent at ortho, meta, and/or para position. X201's each independently represent a single bond or -NR202-. R202's each independently represent a hydrogen atom, a substituted or non-substituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group. The aromatic ring represented by R201 is preferably phenyl or naphthyl, and phenyl is particularly preferred. The aromatic ring represented by R201 may have at least one substituent at substitution sites. Examples of the substituent include halogen atoms, a hydroxyl group, a cyano group, a nitro group, a carboxyl group, alkyl groups, alkenyl groups, aryl groups, alkoxy groups, alkenyloxy groups, aryloxy groups, acyloxy groups, alkoxycarbonyl groups, alkenyloxycarbonyl groups, aryloxycarbonyl groups, a sulfamoyl group alkyl-substituted sulfamoyl groups, alkenyl-substituted sulfamoyl groups, aryl-substituted sulfamoyl groups, a sulfonamide group, a carbamoyl group, alkyl-substituted carbamoyl groups, alkenyl-substituted carbamoyl groups, aryl-substituted carbamoyl groups, an amide group, alkylthio groups, alkenylthio groups, arylthio groups, and acyl groups. The heterocyclic group represented by R201 is preferably aromatic. The aromatic heterocycle is commonly an unsaturated hetero ring, and preferably has its maximum double bonds. The heterocyclic group is preferably a five-, six-, or seven-membered ring, more preferably a five- or six-membered ring, and most preferably a six-membered ring. The hetero atom of the heterocycle is preferably a nitrogen, sulfur, or oxygen atom, and a nitrogen atom is particularly preferred. A particularly preferred aromatic heterocycle is a pyridine ring (preferred heterocyclic groups are 2-pyridyl and 4-pyridyl groups). The heterocyclic group may have a substituent. Examples of the substituent for the heterocyclic group are the same as those of the substituent for the aryls described above. If X201 is a single bond, the heterocyclic group preferably has a nitrogen atom having a free valency. The heterocyclic group with a nitrogen atom having a free valency is preferably a five-, six-, or seven-membered ring, more preferably a five- or six-membered ring, and most preferably-a f ive-membered ring. The heterocyclic group may also have a plurality of nitrogen atoms. In addition, the heterocyclic group may have a hetero atom (for example, 0 or S) other than the nitrogen atom. Examples of the heterocyclic group with a nitrogen atom having a free valency are shown below. In the examples, -C4H9n represents n-C4H9. The alkyl group represented by R202 is preferably a chain alkyl group though it may be a cyclic alkyl group, and is more preferably a linear chain alkyl group rather than a branched chain alkyl group. The number of carbon atoms of the alkyl group ranges preferably from 1 to 30, more preferably from 1 to 20, further preferably from 1 to 10, further preferably from 1 to 8, and most preferably from 1 to 6. The alkyl group may have a substituent. Examples of the substituent include halogen atoms, alkoxy groups (for example, a methoxy group and an ethoxy group), and acyloxy groups (for example, an acryloyloxy group and a methacryloyloxy group). The alkenyl group represented by R202 is preferably a chain alkenyl group though it may be a cyclic alkenyl group, and is more preferably a linear chain alkenyl group rather than a branched chain alkenyl group. The number of carbon atoms of the alkenyl group ranges preferably from 2 to 30, more preferably from 2 to 20, further preferably from 2 to 10, further preferably from 2 to 8, and most preferably from 2 to 6. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the substituent for the alkyl group. The aromatic ring group and the heterocyclic group represented by R202 and their preferred ranges are similar to those of the aromatic ring and the heterocycle represented by R201 and their preferred ranges, respectively. The aromatic ring group and the heterocyclic group may each further have a substituent. Examples of the substituent are the same as those of the substituent for each of the aromatic ring and the heterocycle represented by R201. The compounds represented by General formula (I) can be synthesized by any known method, for example, described in JP-A-2003-344655. The retardation developer is described in detail in Hatsumeikyoukai Kokaigiho (Journal of Technical Disclosure) , Kogi No. 2001-1745, p. 49. Retardation developers usable in the invention may be polymeric additives other than the low molecular weight compounds. The non-phosphate ester polymers used in the invention may also function as retardation developers. Preferred examples of the polymeric retardation developers that also function as non-phosphate ester polymers include the aromatic polyester polymers described above and copolymers of the aromatic;polyester polymers with other resins. The retardation developers in the invention are more preferably Re developers from the viewpoint of effective development of Re to achieve an appropriate Nz factor. Among the retardation developers, examples of the Re developer include disc compounds and rod compounds. In the invention, anti-degradation agents, ultraviolet absorbers, releasing agents, mat agents, lubricants, and plasticizers can be appropriately used if necessary. (Anti-Degradation Agent) At least one anti-degradation (antioxidant) agent may be added to the low-substitution layer and high-substitution layer, and examples thereof include phenol-type and hydroquinone-type antioxidant agents such as 2,6-di-tert-butyl-4-methylphenol, 4,4'-thiobis-(6-tert-butyl-3-methylphenol) , 1,1'-bis(4-hydroxyphenyl)cyclohexane, 2,2'-methylenebis(4-ethyl-6-tert-butylphenol) 2,5-di-tert-butylhydroquinone, and pentaerythrityl tetrakis[3-(3,5-di-tert- butyl-4-hydroxyphenyl)propionate]. Also preferred are phosphonic acid-type antioxidants such as tris(4-methoxy-3,5-diphenyl)phosphite, tris(nonylphenyl)phosphite, tris(2,4-di-tert-butylphenyl)phosphite, bis(2,6-di-tent-butyl-4-methylphenyl)pentaerythritol diphosphite andbis(2, 4-di-tert-butylphenyl)pentaerythritol diphosphite. An amount of the anti-degradation agent to be added may be from 0.05 to 5.0 parts by mass relative to 100 parts by mass of the cellulose acylate. (UV Absorber) The low-substitution layer and high-substitution layer may contain at least one UV absorber. The UV absorber is preferably selected from UV absorbers excellent in absorption ability for light having a wavelength of not longer than 37 0 nm, and having little absorption of light having a wavelength of not shorter than 400 nm, in terms of the good displaying characteristics. Preferred examples of the UV absorber for use in the invention include hindered phenol compounds, hydroxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, and nickel complex compounds. Examples of the hindered phenol compound include 2, 6-di-tert-butyl-p-cresol, pentaerythrityl tetrakis[3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy- hydrocinn amide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl) benzene, and tris-(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate. Examples of the benzotriazole compound include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,2-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol -2-yl)phenol), (2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine, triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate] , N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinn amide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)ben zene, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)-5-chlorobenzotriazole, 2,6-di-tert-butyl-p-cresol, and pentaerythrityl tetrakis[3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate]. An amount of the UV absorbent to be added is preferably from 1 ppm to 1.0%, more preferably from 10 to 1000 ppm with respect to the total mass in the entire cellulose acyiate laminate film. (Peeling Promoter) Preferably, the low-substitution layer and high-substitution layer may contain a peeling promoter. The peeling promoter may be added to the film for the purpose of improving the peeling ability so as to be carried out more stably or more readily. The peeling promoter may be in the film, for example, in a ratio of from 0.001 to 1% by mass. Preferably, the content is at most 0.5% by mass since the releasing agent hardly separates from the film; and also preferably, the content is at least 0.005% by mass since a required release reduction effect may be realized. Accordingly, preferably, the content is from 0.005 to 0.5% by mass, more preferably from 0.01 to 0.3% by mass. The peeling promoter may be selected from any known peeling promoters such as organic and inorganic acid compounds, surfactants, and chelating agents. Above all, polycarboxylic acids and their esters are used effectively; and ethyl esters of citric acid are used more effectively. In an embodiment where the low-substitution layer is laminated on the high-substitution layer, the high-substitution layer is preferably disposed on a surface side of a support such as a belt, and the peeling promoter is preferably added into the high-substitution layer. (Matting Agent) In the high-substitution layer, at least one high-substitution layer preferably contains a matting agent from the view point of lubricity of the film and stable production. The matting agent may be selected from inorganic compounds or organic compounds. Preferred examples of the inorganic matting agent include silicon-containing inorganic compounds such as silicon dioxide, calcined calcium silicate, hydrated calcium silicate, aluminium silicate and magnesium silicate, titanium oxide, zinc oxide, aluminium oxide, barium oxide, zirconium oxide, strontium oxide, antimony oxide, tin oxide, tin-antimony oxide, calcium carbonate, talc, clay, calcined kaolin, and calcium phosphate. More preferred are silicon-containing inorganic compounds and zirconium oxide. Particularly preferred is silicon dioxide since it can reduce haze of cellulose acyiate films. As fine particles of silicon dioxide, commercially-available productions can be used, including, for example, AEROSIL R972, R972V, R974, R812, 200, 200V, 300, R202, OX50 and TT600 (all of them are manufactured by NIPPON AEROSIL CO., LTD. ) . As fine particles of zirconium oxide, for example, those in the market under trade names of AEROSIL R976 and R811 (manufactured by NIPPON AEROSIL CO., LTD.) can be used. Preferable examples of the organic matting agent include polymers such as silicone resins, fluororesins, and acrylic resins. Above all, more preferred are silicone resins. Of silicone resins, even more preferred are those having a three-dimensional network structure. For example, usable are commercially-available products of Tospearl 103, Tospearl 105, Tospearl 18, Tospearl 120, Tospearl 145, Tospearl 3120 and Tospearl 240 (all trade names by Toshiba Silicone), etc. The matting agent may be added to a cellulose acylate solution according to any method so far as desired cellulose acylate solution can be obtained without any problems. For example, the additive may be added in the stage where a cellulose acylate is mixed with a solvent; or the additive may be added to a mixture solution prepared from a cellulose acylate and a solvent. Further, the additive may be added to and mixed with a dope just before the dope is cast, and this is a so-called imminent addition method, in which the ingredients may be on-line mixed by screw kneading. Concretely, preferred is a static mixer such as an in-line mixer. As the in-line mixer, for example, preferred is a static mixer, SWJ (A static tubular mixer, Hi-Mixer, by Toray Engineering). Regarding the mode of in-line addition, JP-A 2003-053752 describes an invention of a method for producing a cellulose acylate film wherein, for the purpose of preventing concentration unevenness and particle aggregation, the distance L between the nozzle tip through which an additive liquid having a composition differing from that of the main material dope and the start end of an in-line mixer is controlled to be at most 5 times the inner diameter d of the main material feeding line, thereby preventing concentration unevenness and aggregation of matting particles, etc. JP-A 2003-053752 discloses a more preferable embodiment, in which the distance (L) between the nozzle tip opening through which an additive liquid having a composition differing from that of the main material dope and the start end of the in-line mixer is controlled to be at most 10 times the inner diameter (d) of the feeding nozzle tip opening, and the in-line mixer is a static non-stirring tubular mixer or a dynamic stirring tubular mixer. More concretely, JP-A 2003-053752 discloses that the flow ratio of the cellulose acylate film main material dope/in-line additive liquid is from 10/1 to 500/1, more preferably from 50/1 to 200/1. JP-A 2003-014933 discloses an invention of providing a retardation film which is free from a trouble of additive bleeding and a trouble of interlayer peeling and which has good lubricity and excellent transparency; and regarding the method of adding additives to the film, the patent reference says that the additive may be added to a dissolving tank, or the additive or a solution or dispersion of the additive may be added to the dope being fed in the process from the dissolving tank to a co-casting die, further describing that in the latter case, mixing means such as a static mixer is preferably provided for the purpose of enhancing the mixing efficiency therein. In the embodiment, the laminate of the low-substitution layer and high-substitution layer has the low-substitution layer as a core layer, and the high-substitution layer disposed on each of the surfaces of the low-substitution layer; more preferably, at least one of the high-substitution layer contains the matting agent, in terms of improving the abrasion-resistant properties caused by reducing the friction coefficient of the film surface, or in terms of preventing the wide-long film from straining or cracking while being wound-up; or even more preferably, both of the high-substitution layers contain the matting agent, in terms of improving the abrasion-resistance, or in terms of preventing the straining. The matting agent does not increase the haze of the film so far as a large amount of the agent is not added to the film. When the film containing a suitable amount of a matting agent is actually used in LCD, the film may not suffer from disadvantages such as the low contrast and the bright spots. Not too small amount of the matting agent in the film may achieve the prevention of the cracking and the improvement of the abrasion-resistance. From these viewpoints, an amount of the matting agent is preferably from 0.01 to 5.0% by mass, more preferably from 0.03 to 3.0% by mass, even more preferably from 0.05 to 1.0% by mass. (Haze) The low-substitution layer or the laminate of the low-substitution layer and high-substitution layer preferably has a haze of less than 0.20%, more preferably less than 0.15%, particularly preferably less than 0.10%. Having a haze of less than 0.20%, the film can improve contrast ratio of a liquid crystal display device incorporating it and the transparency of the film is enough high to use as an optical film. In a preferable embodiment, the high-substitution layer disposed on at least one of the surfaces of the low-substitution layer. A single type of the cellulose acylate having the uniform degree of the acylation or plural types of the cellulose acylates having the different degrees of the acylation may be contained in each of the layers. Preferably, the degree of the acylation of the cellulose acylate contained in each of the layers is uniform, in terms of adjusting the optical properties. In case where the cellulose acylate film is produced according to a solution casting method, preferably, the layer in contact with the support (hereinafter this may be referred to as a skin B layer) is the high-substitution layer and the other layer is the low-substitution layer, from the viewpoint of improving the releasability of the film from the support in the solution casting method. Preferably, the cellulose acylate film has a three or more multi-layered laminate structure, in terms of the dimensional stability or in terms of reducing the curling caused by an environmental humidity/temperature variation. Also preferably, the high-substitution layer is on both surfaces of the low-substitution layer in terms of broadening the latitude in the step of achieving the desired optical properties. More preferably, the film of the invention has a three or more multi-layered laminate structure, in which all the cellulose acylate contained in at least one internal layer is the cellulose acylate fulfilling the conditions of the above formulas (3) and (4), and all the cellulose acylate contained in the two surface layers is the cellulose acylate fulfilling the conditions of the above formulas (5) and (6). Only in the embodiments having a three or more multi-layered laminate structure, the surface layer not in contact with the support in the film formation is occasionally referred to as a skin A layer. Preferably, the invention has a three-layered structure of skin B layer/core layer/skin A layer. The cellulose acylate film having a three-layered structure may have a constitution of high-substitution layer/low-substitution layer/high-substitution layer, or a constitution of low-substitution layer/high-substitution layer/low-substitution layer; but preferably, the film has a constitution of high-substitution layer/low-substitution layer/high-substitution layer in terms of the releasability of the film from the support in solution-casting film formation and in terms of the dimensional stability of the film. In the cellulose acylate film having a three-layered structure, preferably, the cellulose acylate to be in both surface layers is one having the same degree of acyl substitution in terms of the production cost and the dimensional stability of the film and in the terms of reducing the curling of the film caused by an environmental humidity/heat variation. (Film Thickness) Preferably, the mean thickness of the low-substitution layer is from 30 to 100 micro meters, more preferably from 30 to 80 micro meters, even more preferably from 30 to 70 micro meters. When the low-substitution layer has a mean thickness of equal to or more than 30 micro meters, the handlability of the film is improved, which is preferable. When the low-substitution layer has a mean thickness of equal to or less than 70 micro meters, the film may readily follow the ambient humidity variation and may keep its optical properties. The mean thickness of at least one high-substitution layer is preferably from 0.2% to less than 25% of the mean thickness of the low-substitution layer. When it is equal to or more than 0.2%, the peeling abilities of the film may be sufficient, and the film may not suffer from streaky surface unevenness, thickness unevenness and uneven optical properties of the film; and when it is less than 25%, the optical properties of the low-substitution layer may be effectively used and the film may achieve sufficient optical properties. The mean thickness of at least one high-substitution layer is more preferably from 0.5 to 15% of the mean thickness of the low-substitution layer, even more preferably from 1. C to 10% of the mean thickness of the low-substitution layer. Still more preferably, the mean thickness of both the skin layers A and B are from 0.2% to less than 25% of the mean thickness of the core layer. Preferably, the mean thickness of the low-substitution layer is from 30 to 100 micro meters, and the mean thickness of at least one high-substitution layer is from 0.2% to less than 25% of the mean thickness of the low-substitution layer, in terms of the wavelength dispersion characteristics of retardation of the film. More preferably, the mean thickness of the low-substitution layer is from 30 to 100 micro meters, and the mean thicknesses of both high-substitution layers are from 0.2% to less than 25% of the mean thickness of the low-substitution layer. In the embodiments in a two or more multi-layered structure, preferably, the thickness of the low-substitution layer (preferably, the thickness of the core layer) is from 30 to 70 micro meters, more preferably from 30 to 60 micro meters, even more preferably from 30 to 50 micro meters. In the embodiments in two or more multi-layered structure, preferably, the thickness of the high-substitution layer (preferably, the thickness of the surface layer on both sides of the film) is from 0.5 to 20 micro meters, more preferably from 0.5 to 10 micro meters, even more preferably from 0.5 to 3 micro meters. In an exemplary laminated structure having three layers, an inner layer (a core layer) corresponds to the low-substitution layer, and surface layers (a skin layer B and a skin layer A) each corresponds to the high-substitution layer. More preferably, the skin layers B and A each have a smaller thickness than that of the core layer. The preferred conditions on the thickness of the surface layer are the same as those in a laminated structure having three or more layers. (Width of Film) The width of the film composed of the low-substitution layer or of the film composed of the low-substitution layer and the high-substitution layer ranges preferably from 700 to 3000 mm, more preferably from 1000 to 2800 mm, and most preferably from 1500 to 2500 mm. In addition, the film preferably has a width of 700 to 3000 mm, and a ARe of 10 nm or less. (Method of Manufacturing Low-Substitution Cellulose Acylate Film) An exemplary method of manufacturing a low-substitution cellulose acylate film, which refers to the film composed of the low-substitution layer or the film composed of the low-substitution layer and the high-substitution layer, involves forming a cellulose-acylate lamination film through sequential casting or simultaneous co-casting of a cellulose acylate solution for a low-substitution layer containing a cellulose acylate satisfying Formula (1) and an non-phosphorylated ester compound if desired, and a cellulose acylate solution for a high-substitution layer containing the cellulose acylate satisfying Formula (2) , and stretching the film containing 5 mass% residual solvent relative to the total mass of the film at a temperature of Tg-30°C or more, where Tg refers to a glass transition temperature of the cellulose-acylate lamination film. Preferably, the cellulose acylate laminate film is formed according to a solvent casting method. For production examples for cellulose acylate film according to a solvent casting method, referred to are U.S. Pat. Nos. 2,336,310, 2,367,603, 2,492,078, 2,492,977, 2,4 92,978, 2,607,704, 2,73 9, 0 69 and 2,739,070, British Patents 64 0731 and 736892, JP-B 45-4554 and 49-5614, JP-A 60-176834, 60-203430 and 62-115035. The cellulose acylate film may be stretched. For the method and the condition for stretching treatment, referred to are, for example, JP-A 62-115035, 4-152125, 4-284211, 4-298310, 11-48271. Examples of the solution casting method include a method of uniformly extruding a prepared dope through a pressure die onto a metal support, a doctor blade method of regulating the thickness of the dope once cast on a metal support, with a blade, and a method with a reverse roll coater of regulating the thickness with a reverse-rotating roll. Preferred is the method with a pressure die. Examples of the pressure die include a coat hanger-type die, and a T-die. Any of these is favorably used herein. Apart from the methods mentioned herein, any other various known methods of forming a cellulose triacetate solution into films are also employable. In consideration of the difference in the boiling point of the solvent to be used, the conditions may be set, and the same advantages as in the reference publications can be attained here. The low-degree substitution film is produced in a process comprising a step of forming a film by applying the cellulose acylate solution (casting dope) for low-substitution layer that contains a cellulose acylate fulfilling the condition of formula (1) and, if desired, a non-phosphate ester compound, and the cellulose acylate solution for high-substitution layer that contains a cellulose acylate fulfilling the condition of formula (2) onto a support, and a step of stretching the resulting film. In the production method, preferably, the viscosity at 25 degrees Celsius of the cellulose acylate solution for low-substitution layer is higher by at least 10% than the viscosity at 25 degrees Celsius of the cellulose acylate solution for high-substitution layer, in terms of the transversal distribution of the laminate film layers and in terms of the aptitude for production of the laminate film. For preparing the low-degree substitution cellulose acylate film, a laminate casting method such as a co-casting method, a sequential casting method, and a coating method are preferably used. A simultaneous co-casting method is more preferable in terms of improving the stability of production and reducing the production cost. In the embodiments where the low-degree substitution cellulose acylate film is prepared according to a co-casting method or a sequential casting method, at first, a cellulose acetate solution (dope) for each layer is prepared. In the co-casting method (superimposition simultaneous casting), casting dopes to be the constitutive layers (three or more layers) are extruded out through a casting T-die of simultaneously extruding the dopes through the respective slits onto a casting support (band or drum), and simultaneously cast thereon, and then peeled off from the support at a suitable time to give a film. FIG. 2 is a cross-sectional view showing the condition of simultaneous extrusion and casting of a surface layer dope 1 and core layer dopes 2 onto a casting support 4 through a co-casting T-die 3, thereby forming three layers on the support. In the sequential casting method, a casting dope for the first layer is first extruded out and cast through a casting T-die onto a casting support, and after it is dried or not, a casting dope for the second layer is extruded out and cast onto it through a casting T-die, and in that manner, if desired, other dope(s) are cast and laminated on the previous layer up to be three (or more) layers, and at a suitable time, the resulting laminate is peeled off from the support and dried to be a film. In the coating method, in general, a film of the core layer is formed according to a solution casting method, then a coating liquid to be the surface layer is prepared, and using a suitable coating unit, the coating liquid is applied onto the core film on one side thereof at a time or on both sides simultaneously, and dried to give a laminate-structured film. As the endlessly running metal support for use in producing the film of the invention, usable is a drum of which the surface is mirror-finished by chromium plating, or a stainless belt (band) of which the surface is mirror-finished by polishing. One or more pressure dies may be arranged above the metal support. Preferably, one or two pressure dies are arranged. In case where two or more pressure dies are arranged, the dope to be cast may be divided into portions suitable for the individual dies; or the dope may be fed to the die at a suitable proportion via a plurality of precision metering gear pumps . The temperature of the cellulose acylate solution to be case is preferably from -10 to 55 degrees Celsius, more preferably from 25 to 50 degrees Celsius. In this case, the solution temperature may be the same throughout the entire process, or may differ in different sites of the process . In case where the temperature differs in different sites, the dope shall have the desired temperature just before cast. The method involves stretching the formed film containing 5 mass% residual solvent relative to the total mass of the film at a temperature of Tg-30°C or more. For example, the stretching imparts desirable optical properties more particularly wavelength dispersion characteristics to the film, and desirable retardation to the cellulose acylate film. The cellulose acylate film is preferably stretched in either a film conveying direction or a direction (width direction) perpendicular to the conveying direction, and is more preferably stretched in a direction (width direction) perpendicular to the conveying direction from the viewpoint of a subsequent polarizing-plate processing step using the cellulose acylate film. Such stretching of a film in the width direction is disclosed in JP-A-62-115035, JP-A-4-152125, JP-A-4-284211, JP-A-4-298310, and JP-A-11-48271, for example. In stretching of a film in the longitudinal direction, for example, the rotation speed of a film conveying roller is adjusted such that the film winding rate is higher than the film separation rate, thereby the film is stretched. In stretching of a film in the width direction, while a film is conveyed with its two lateral ends held by a tenter, the width of the tenter is gradually expanded, thereby the film can also be stretched. A dried film can be stretched with a stretching machine preferably through uniaxial stretching with a long stretching machine. The stretching ratio of the low-substitution cellulose acylate film ranges preferably from 5% to 200%, more preferably from 5% to 100%, and most preferably from 5% to 50%. If the low-substitution cellulose acylate film is used as a protective film for a polarizer, the transmission axis of the polarizer must be disposed parallel or orthogonal to the in-plane slow axis of the low-substitution cellulose acylate film in order to suppress light leakage in oblique view of a polarizing plate. The transmission axis of a polarizer, which is continuously produced into a rolled film, is typically parallel to a width direction of the rolled film; hence, the in-plane slow axis of the protective film in a rolled form must be parallel or orthogonal to the width direction of the film in order to continuously bond the polarizer in a rolled form to the protective film composed of the low-substitution cellulose acylate film in a rolled form. Thus, it is preferred the film be further stretched in the width direction. The film may be stretched in the middle of film formation step, or a rolled-up film may be stretched. In the above-described manufacturing process of the film, the film containing a residual solvent is preferably stretched in the middle of the film formation step. Preferably, the production method preferably further comprises a step of drying the cellulose acylate laminate film after the stretching step, and a step of stretching the dried cellulose acylate laminate film at a temperature of equal to or higher than Tg-10 degrees Celsius, in terms of enhancing the retardation of the film. For drying the dope on a metal support in production of the low-degree substitution cellulose acylate film, generally employable is a method of applying hot air to the surface of the metal support (drum or belt), or that is, on the surface of the web on the metal support; a method of applying hot air to the back of the drum or belt; or a back side liquid heat transfer method that comprises contacting a temperature-controlled liquid with the opposite side of the dope-cast surface of the belt or drum, or that is, the back of the belt or drum to thereby heat the belt or drum by heat transmission to control the surface temperature thereof. Preferred is the backside liquid heat transfer method. The surface temperature of the metal support before the dope is cast thereon may be any degree so far as it is not higher than the boiling point of the solvent used in the dope. However, for promoting the drying or for making the dope lose its flowability on the metal support, preferably, the temperature is set to be lower by from 1 to 10 degrees Celsius than the boiling point of the solvent having the lowest boiling point of all the solvents in the dope. In case where the cast dope is peeled off after cooled but not dried, then this shall not apply thereto. For controlling the thickness of the film, the solid concentration in the dope, the slit gap of the die nozzle, the extrusion pressure from the die, and the metal support speed may be suitably regulated so that the formed film could have a desired thickness. Produced in the manner as above, the length of the low-degree substitution cellulose acylate film is preferably from 100 to 10000 m per roll, more preferably from 500 to 7000 m, even more preferably from 1000 to 6000 m. In rolling up the film, preferably, at least one edge thereof is knurled, and the knurling width is preferably from 3 mm to 50 mm, more preferably from 5 mm to 30 mm, and the knurling height is preferably from 0.5 to 500 micro meters, more preferably from 1 to 200 micro meters. This may be one-way or double-way knurling. Optically Compensatory Film: In an embodiment of the invention where the low-substitution layer is provided as an outer protective film of the polarizer, an optically compensatory film can be disposed between each of the pair of polarizers and the liquid crystal cell. The optically compensatory film includes a support composed of a polymer film, and an optically anisotropic layer the orientation of which is fixed to hybrid alignment. The optically compensatory film provided together with the low-substitution layer leads to an improvement in viewing angle characteristics in addition to the advantageous effects of the invention, i.e., a reduction in frame-like light leakage. Either rod-like liquid crystal or discotic liquid crystal may be used as a liquid crystal compound used in formation of the optically anisotropic layer. The discotic liquid crystal is preferred from the viewpoint of an improvement in viewing angle characteristics. Examples of the discotic liquid crystal include triphenylene compounds and trisubstituted benzene compounds. In particular, the triphenylene compounds are preferred, examples of which include the compounds represented by General formula (DI) and the specific examples thereof described in paragraphs [0033] to [0098] in JP-A-2009-98645. In addition, JP-A-2009-98645 also discloses additives usable in the formation of the optically anisotropic layer and a formation procedure thereof. In the optically anisotropic layer, the molecules of the liquid crystal compound are fixed to hybrid alignment. In the hybrid alignment, an angle (hereinafter, referred to as "tilt angle") , which is defined by a major axis of each molecule and a layer plane in the rod-like liquid crystal, or defined by a discotic plane of each molecule and a layer plane in the discotic liquid crystal, varies (increases or decreases) in a layer thickness direction. The optically anisotropic layer is commonly formed by aligning a composition containing a discotic liquid crystal compound on a surface of the alignment film; hence, the optically anisotropic layer has an interface with the alignment film and an interface with air. In an embodiment of the hybrid alignment, the tilt angle is large in a region close to the alignment film interface, and small in a region close to the air interface, namely, the tilt angle decreases from the alignment film interface toward the air interface (hereinafter, referred to as "reversed hybrid alignment"). In another embodiment of the hybrid alignment, the tilt angle is small in the region close to the alignment film interface, and large in the region close to the air interface, namely, the tilt angle increases from the alignment film interface toward the air interface (hereinafter, referred to as "normal hybrid alignment"). Although the optically anisotropic layer may have either hybrid alignment from the viewpoint of viewing angle contrast, the reversed hybrid alignment is preferred from the viewpoint of front contrast. The optically compensatory film having the optically anisotropic layer containing the discotic liquid crystal fixed to hybrid alignment preferably exhibits the following optical characteristics. The retardation R[0°] for incident light having a wavelength of 550 run, which is measured from a normal direction to the optically compensatory film, preferably satisfies the following expression: 10 nm10, is 320° or more. B: total of vertical and horizontal angles, each providing CR>10, is more than 240° to less than 320°. C: total of vertical and horizontal angles, each providing CR>10, is more than 200° to less than 240°. D: total of vertical and horizontal angles, each providing CR>10, is more than 160° to less than 200°. E: total of vertical and horizontal angles, each providing CR>10, is 160° or less. *1: "High" refers to a single structure of a high-substitution layer, "Low" refers to a single structure of a low-substitution layer, and "High-low" refers to a laminate of a high-substitution layer and a low-substitution layer, where the high-substitution layer is adjacent to a polarizer. Liquid crystal displays were produced as in Example 1 except that the inner protective film (support) was changed from Film 1 to Films 6, 7, 8, and 14, and the display performance of each liquid crystal display was evaluated as in Example 1. The results are shown in Table 4. The liquid crystal displays produced using Films 6, 7, 8, and 14 exhibited reduced frame-like light leakage and improved display characteristics as in Example 1. Table 4 also shows the results of Example 1. *1: "High" refers to a single structure of a high-substitution layer, "Low" refers to a single structure of a low-substitution layer, and "High-low-high" refers to a laminate of a high-substitution layer, a low-substitution layer, and a high-substitution layer, where one of the high-substitution layers is adjacent to a polarizer. All the liquid crystal displays of Examples of the invention exhibit reduced frame-like light leakage. The cause of this effect is speculated as follows. In each of the liquid crystal displays of Examples, the film consisting of or including the low-substitution layer (about 60 (im in thickness) is disposed as inner and/or outer protective films of a polarizer; hence, the thickness of the optically-compensatory film can be reduced by about 2 0 pm compared with the liquid crystal display of the comparative example, resulting in a reduction in distortion of the liquid crystal panel and/or the polarizing plate due to, for example, heat. 4. Example 14 The liquid crystal display of Example 5 was modified to a liquid crystal display of Example 14, as follows. (Formation of Alignment Film) A coating solution for alignment layer, having the following composition, was continuously applied onto a saponified surface of Film 13 with a #16 wire bar. The coating was then dried in hot air at 60°C for 60 sec and then at 90°C for 150 sec. The surface of the resultant coating was rubbed through rotation of a rubbing roll at 500 rpm in a direction parallel to a conveying direction to give an alignment film. (Composition of Coating Solution for Alignment Film) Modified polyvinyl alcohol described below 20 parts by mass Water 360 parts by mass Methanol 120 parts by mass Glutaraldehyde (crosslinking agent) 1 part by mass Modified polyvinyl alcohol - -CM) Q2 -dCO—fi V-OHCM-O-CO-CHsCHa (Formation of Optically Anisotropic Layer) The coating solution was continuously applied onto the surface of the alignment film on Film 13 with a #3.2 wire bar. The solvent in the coating was evaporated during a step of continuously heating the coating from room temperature to 100°C, and the coating was then heated for about 90 sec in a drying zone at 135°C in such a manner that wind velocity in a direction parallel to the film conveying direction was 1.5 m/sec at a surface of the discotic liquid crystal compound layer, thereby the discotic liquid crystal compound was aligned. The coating was then conveyed into a drying zone at 80°C. In the drying zone, the discotic liquid crystal compound was irradiated with ultraviolet rays at an illuminance of 600 mW for 4 sec by an ultraviolet irradiator (UV lamp, output power: 160 W/cm, emission wavelength: 1.6m) while the film surface temperature was kept at about 100°C, thereby the discotic liquid crystal compound was fixed to that alignment through a crosslinking reaction. The coating was then cooled to room temperature to form an optically anisotropic layer on the surface of Film 13, resulting in production of an optically compensatory film. (Composition of Coating Solution for Optically Anisotropic Layer) Methyl ethyl ketone 98 parts by mass Discotic liquid crystal compound (1) described below 41.01 parts by mass Ethylene oxide modified trimethlolpropanetriacrylate 4.06 parts by mass (V#360, from Osaka Organic Chemicals Co., Ltd.), Cellulose acetate butyrate 0.34 part by mass (CAB551-0. 2, from Eastman Chemical Company) Cellulose acetate butyrate 0.11 part by mass (CAB531-1, from Eastman Chemical Company) Fluoro-aliphatic-group-containing polymer 1 described below 0.13 parts by mass Fluoro-aliphatic-group-containing polymer 2 described below 0.03 parts by mass Photopolymerization initiator 1.35 parts by mass (IIRGACURE 907, from Ciba Geigy) Sensitizer 0.45 parts by mass (KAYACURE DETX, from NIPPON KAYAKU CO., LTD.) Discotic liquid crystal compound 1 Fluoro-aliphatic-group-containing polymer 1 (a/b/c=20/20/60 (wt%)) Fluoro-aliphatic-group-containing polymer 2 (a/b=98/2 (wt%)) (Measurement of Optical Characteristic) The retardation in-plane Re (550) at a wavelength of 550 ran of the optically compensatory film was determined as 44 ran with KOBRA-WR (from Oji Scientific Instruments). Light having a wavelength of 550 ran was incident from a direction tilted by ±40° from a normal direction in a plane orthogonal to the slow axis of the optically compensatory film to measure the retardations R[ + 40°] and R[-40°], and the calculated ratio R [ + 40°] /R [-40°] was 3.2. The Re was measured while the optically compensatory film was placed in a direction giving R[ + 40°] > R[-40°] . This revealed that the discotic liquid-crystal compound was hybrid-aligned in the optically anisotropic layer. A TN-mode liquid crystal display was produced, which had a similar configuration to that in Example 5 except that two optically compensatory films prepared as described above were bonded to the surfaces of the polarizer as inner protective films instead of Film 5. The resultant TN-mode liquid crystal display exhibited reduced frame-like light leakage as in Example 5 and noticeably improved CR viewing angle characteristics compared with those in Example 5. Evaluation on CR viewing angle: A. 5. Examples 15 to 19 A surface of a comme'rcially available norbornene polymer film "ZEONOR ZF14-060" (from Optes) was subjected to corona discharge treatment with a solid state corona discharger 6KVA (from Pillar) to give Film 15. Film 15 had a thickness of 60 pm. Film 15 had an Re (550) of 2 nm and an Rth (550) of 3 nm. A surface of a commercially available cycloolefin polymer film "ARTON FLZR50" (from JSR Corp.) was subjected to corona discharge treatment as in Film 15 to give Film 16. Film 16 had a thickness of 50 |um. Film 16 had an Re (550) of 2 nm and an Rth (550) of 2 nm. A stretched film (protective film A) was prepared in accordance with the description in paragraphs [0223] to [0226] of JP-A-2007-127893. An adhesive-layer coating composition P-2 was prepared in accordance with the description in paragraph [0232] of JP-A-2007-127893, and the composition was applied onto the surface of the stretched film in accordance with the description in paragraph [0246] thereof to form the adhesive layer to give Film 17. Film 17 had a thickness of 31 |um. Film 17 had an Re (550) of 1 nm and an Rth (550) of 1 nm. A propylene/ethylene random copolymer containing approximately 5 mass% of ethylene unit (Sumitomo Noblen W151, from Sumitomo Chemical Co., Ltd.) was extruded from a uniaxial melt extruder having a T-die at a melt temperature of 2 60°C to yield a primary film.. The two sides of the primary film were then subjected to corona discharge treatment to give Film 18. Film 18 had a thickness of 81 (Jin.. Film 18 had an Re (550) of 7 nm and an Rth (550) of 28 nm. Polyethylene terephthalate (PET) was synthesized in a usual manner and processed into chips. The PET chips were then dried into a water content of 50 ppm or less in a paddle dryer, and then was melted in an extruder while the temperature of the heater was set to 280 to 300°C. The melted polyester resin was discharged from a die onto an electrostatically charged chiller roll to yield an amorphous base. The amorphous base was stretched into a stretching ratio of 3.3 in a base flow direction, and was then stretched into a stretching ratio of 3.9 in a width direction to give Film 19. Film 19 had a thickness of 78 \m. Film 19 had an Re (550) of 1400 rati and an Rth (550) of 7CG0 ran. Liquid crystal displays (Examples 15 to 19) were produced as in Example 1 except that the outer protective films (on the viewing side and the BL side) were changed from Film 5 to Films 15, 16, 17, 18, and 19, respectively, and display performance of each liquid crystal display was evaluated as in Example 1. The liquid crystal displays of Examples 15 to 19 produced using Films 15, 16, 17, 18, and 19 exhibited reduced frame-like light leakage and improved display characteristics as in Example 1. (Evaluation on Light Leakage at High Humidity Condition) The liquid crystal display of Example 1 and the liquid crystal displays of Examples 15 to 19 produced using Films 15, 16, 17, 18, and 19 were held at 60°C and 90% RH for 100 hr in a constant temperature and humidity room, and were then taken out. The liquid crystal displays were then turned into an entirely black display mode and visually observed in a dark room to evaluate light leakage in accordance with the following criterion. Good: substantially no light leakage was observed (practically no problem). Allowable: some light leakage was observed though it was practically not problematic. Although the liquid crystal display of Example 1 was evaluated as "Allowable", the liquid crystal displays of Examples 15 to 19 were each evaluated as "Good", showing high moisture resistance. What is claimed is: 1. A twisted-alignment-mode liquid crystal display comprising: a pair of polarizers disposed such that the polarization axes are orthogonal to each other; a twisted-alignment-mode liquid crystal cell disposed between the polarizers; and a low-substitution layer comprising cellulose acylate satisfying Formula (1) as a main component, (1) 2.CKZK2.7, where Zl represents the total degree of substitution of acyl groups of the cellulose acylate in the low-substitution layer. 2. The liquid crystal display according to claim 1, wherein the low-substitution layers are each disposed between the pair of polarizers and the twisted-alignment-mode liquid crystal cell. 3. The liquid crystal display according to claim 2, wherein the low-substitution layer has a retardation, in-plane Re (550) of -50 to 150 run and a retardation along the thickness direction Rth (550) of -50 to 200 nm at a wavelength of 550 nm. 4. The liquid crystal display according to any one of claims 1 to 3, wherein the low-substitution layers are each provided on an outer surface of each of the pair of polarizers. 5. The liquid crystal display according to claim 1, wherein the low-substitution layers are each disposed on an outer surface of each of the pair of polarizers, and are not disposed between each of the pair of polarizers and the twisted-alignment-mode liquid crystal cell, and the liquid crystal display comprises optically anisotropic layers between each of the pair of polarizers and the twisted-alignment-mode liquid crystal cell, the optically anisotropic layers comprising liquid crystal compounds which are fixed to be in a state of hybrid alignment. 6. The liquid crystal display according to any one of claims 1 to 5, wherein the low-substitution layer has a thickness of 30 to 80 pm. 7. The liquid crystal display according to any one of claims 1 to 6, wherein the low-substitution layer further comprises a non-phosphate ester compound. 8. The liquid crystal display according to any one of claims 1 to 7, which comprises a high-substitution layer disposed on at least one surface of the low-substitution layers, and the high-substitution layer comprising cellulose acylate satisfying Formula (2) as a main component, (2) 2.7