Description Title of Invention I-IOT-DIP ZINC-BASED PLATED STEEL SHEET Teclllical Field [OOOl] The present invention relates to a hot-dip zinc-based plated steel sheet. 10 Background Art [0002] These days, to protect the environment and prevent global wanning, the suppression of the consumption of fossil fuel is increasingly demanded, and the demand influences various manufacturing industries. For example, autotnobiles, 15 which are indispensable to daily life and activity as a moving means, are no exception, and improvemetits in fuel efficiency etc. by the weight reduction of car bodies etc. are required. I-iowevel; for automobiles, simply achieving a weight reduction of the car body is not permitted in terms of the functionality of the product, and it is necessary to ensure proper safety. 20 [0003] Most of the structure of the automobile is formed of iron-based materials, in particular steel sheets, and the reduction in the weight of the steel sheet is important to the weight reduction of the car body. However, as described above, sirnply reducing the ureiglit of the steel sheet is not permitted, and ensuring the mechanical 25 strength of the steel sheet is required at the same time. Such a detiia~ldo n the steel sheet is placed not only in the automobile manufacturing industry but also in various manufacturing industries similarly. Hence, research and development are being made to enhance the ~nechanicals trength of the steel sheet and thereby obtain a steel sheet in which the nlechanical strength can be maintained or improved even when tlie 30 wall thickness is made smaller than tliose of conventionally used steel sheets. [0004] In general, a material having high mechanical strength tends to decrease in shape fixability in molding such as bending, and is difficult to mold into a complicated shape. As a means for solving such a problem with moldability, what is called "the hot pressing method (also called the hot stamping method or the die 5 quenching method)" is given. In the hot pressing method, a material to be molded is once heated to high temperature, the steel sheet softened by heating is pressed to be molded, and then cooling is performed. By the hot pressing method, the material of the object can be easily pressed because the material is once heated to high temperature and softened. Furthennore, the mechanical strength of the material can 10 be enhanced by the quenching effect by the cooling after molding. Thus, a molded product in which both good shape fixability and high mechanical strength are achieved can be obtained by the hot pressing method. [OOOS] However, when the hot pressing method is used for a steel sheet, the surface 15 of the steel sheet is oxidized by the steel sheet being heated to a high temperature of 800°C or more, and scales (compounds) are produced. Hence, the process of removing the scales (what is called a descaling process) is needed after hot pressing is performed, and productivity is reduced. In addition, in a member etc. requiring corrosion resistance, it is necessary to perform anti-rust treatment or metal covering 20 on the surface of the member after processing, and a surface cleaning process and a surface treatment process are needed; consequently, productivity is further reduced. [0006] As a method to suppress such a reduction in productivity, for exalnple, a method in which a steel sheet to be hot pressed is provided with a covering in 25 advance is given. Various materials such as organic-based materials and inorganicbased materials are generally used as the covering on the steel sheet. Among these, plated steel sheets based on zinc (Zn), which has a sacrificial anti-corxosion action on the steel sheet, are widely used as automotive steel sheets etc. from the viewpoints of the anti-corrosion capacity and the steel sheet production tech~lique. 30 [0007] By providing a Zn-based metal covering, the production of scales on the surface of the steel sheet can be prevetlted, and processes such as descaling become uimecessary; thus, the productivity of molded products is improved. In addition, the Zn-based metal covering l~asal so an anti-rust effect, and therefore also corrosion resistance is improved. Patent Literature 1 to Patent Literature 4 below disclose a 5 method of hot pressing a plated steel sheet that is obtained by providing a Zn-based metal covel.iag to a steel sheet having a prescribed component composition. [OOOS] In Patent Literature 1 to Patent Literature 3 below, a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet is used as a steel sheet for hot 10 pressing. By using a hot-dip galvanized steel sheet oi an alloyed hot-dip galvanized steel sheet for hot pressing, a structure member car1 be molded without iron oxides (that is, scales) being formed on the surface. Further, in view of the fact that, when a Zn oxide layer is formed thick on the surface of a heat-treated steel material obtained by hot pressing a Zn-based plated steel sheet, the coating film adhesiveness 15 and the post-coating corrosion resistance of the heat-treated steel material are adversely affected, Patent Literature 4 below discloses an invention in \vhich a heattreated steel material is subjected to shot blasting to remove a Zn oxide layer or is subjected to coating after the thickness of a Zn oxide layer is reduced. [0009] 20 Patent Literature 5 and Patent Literature 6 below disclose an in\~ention that improves the coating film adhesiveness and the post-coating corrosion resistance of a heat-treated steel material obtained by hot pressing a Zn-based plated steel sheet. Patent Literature 5 below discloses an invention in which a hot-dip galvanized steel sheet with its surface covered with a silicone resin coating film is used as a steel 25 sheet for hot pressing, and Patent Literature 6 below discloses an invention in which a hot-dip galvanized steel sheet covered with a barrier layer containing phosphorus (P) and silicon (Si) (a phosphate is give11 as an example of P, arid colloidal silica is given as an example of Si) is used as a steel sheet for hot pressing. [OOl 01 30 Patent Literature 7 below discloses a technology in which elements that are easier to oxidize tliall Zn (easily oxidizable elements) are added into a galvanized layer and an oxide layer of these easily oxidizable elements is formed on the outer layer of the galvanized layer during the tetnperature increase in hot pressing, and thereby the volatilizatior~o f Zn is prevented. [OOll] 5 According to the inventions disclosed by Patent Literature 5 to Patent Literature 7 below, si~lce a galvanized layer is covered with the barrier layer described above, the vaporization of Zn is suppressed, and thus the adhesiveness of an intermediate coating film and an over-coating film and post-coating corrosion resistance are good. Citation List Patent Literature [0012] Patent Literature 1: Patent Literature 2: Patent Literature 3: Patent Literature 4: Patent Literature 5: Patent Literature 6: Patent Literature 7: Summary of Invention Technical Problem [0013] 26 Ho~ever, when a Zn-based plated steel sheet, in particular a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet, is hot pressed, there is a case where a phosphate coating film fornled by phosphate treatment adheres less easily (that is, phosphate treatability is low). The hot-dip zinc-based plating dealt with by the present invention contains A1 in a plating bath and a plating 30 layer even in cases other than Zn-Al-based alloy plating containing aluminum (Al) as a main componetlt. The reason is as follows. That is, the temperature of the plating bath is approximately 440 to 480°C; in this temperature range, when Zn and Fe come into contact, Fe and Zn are continuously alloyed, and consequently dross occurs. By putting A1 in the plating bath, the reaction between Fe and A1 occurs before the reaction between Fe and Zn occurs, and consequently the occurrence of 5 dross is suppressed. For this reason, usually A1 is contained in a hot-dip galvanizing bath. [0014] In general, in hot-dip galvanizing, A1 is contained at 0.2 to 0.3% in the plating bath, and 0.2 to 1.0 mass% of A1 is contained in the plating layer; in alloyed 10 hot-dip galvanizing, Al is contained at 0.1 to 0.2% in the plating bath, and 0.1 to 0.5 mass% of A1 is contained it1 the plating layer. [OO 1 51 The A1 in the plating layer diffuses atid moves to the outer layer of the plating layer not only during the fo~mationo f a plating coating film but also during 15 the heating of hot pressing, and fomls an A1 oxide film. Since the Al oxide film does not dissolve in phosphoric acid, the reaction between Zn atid a phosphate (zinc phosphate etc.) is inhibited, and a phosphate coating film is less likely to be formed in the area where the A1 oxide film is formed. Consequently, phosphate treatability is low in ttie area where the A1 oxide film is formed. In particular, phosphate 20 treatability is significantly reduced in the case where, in the hot pressing process, the steel sheet is rapidly heated to the Ac3 point or more by etiergization heating or induction heating and then press molding is quickly performed. In this case, also coating adhesiveness is reduced. [0016] 25 In addition, when the present inventors conducted a check experiment on a heat-treated steel material disclosed by Patent Literature 5 above that was obtained by using, as a steel sheet for hot pressing, a hot-dip galvanized steel sheet with its surface covered with a silicone resin coating film, it has been found that, as \\rill be described later, although post-coating corrosion resistance in a cycle corrosion test in 30 wliicli a d ~aynd a wet environmetit are repeated is good, coating adhesiveness is not always good. I-Ience, a heat-treated steel material obtained by the it~\~entioti disclosed in Patent Literature 5 above is not suitable for use as it is for a part or a member in which water is likely to collect because of the structure (for example, a bag-like st~~~ctupraartl below the door, a member with a closed cross section in the engine compartment, etc.), for example. 5 [0017] On the other hand, the addition of easily oxidizable elements into a zinc plating layer disclosed in Patent Literature 7 above requires new operational actions, such as the temperature control of the plating bath and dross measures. [0018] 10 Thus, the present invention has been made in view of the issue nlentioned above, and an object of the present invention is to provide a hot-dip zinc-based plated steel sheet excellent in coating film adhesiveness after hot pressing more conveniently. 15 Solution to Problem 1001 91 On the basis of the findings obtained by extensive studies on the plated steel sheet for hot pressing of the object mentioned above, the present inventors have thought up the following hot-dip zinc-based plated steel sheet. 20 The gist of the present invention is as follows. [0020] (1) A hot-dip zinc-based plated steel sheet comprising: a hot-dip zinc-based plated steel sheet that is a base metal; and a surface treatment layer formed on at least one surface of the hot-dip zincbased plated steel sheet, wherein the surface treatment layer contains one or more oxides selected fro111 zirconia, lanthanum oxide, cerium oxide, and neodymium oxide each having a particle size of more than or equal to 5 nm and less than or equal to 500 nm, in a 30 range of more than or equal to 0.2 ghn2 and less than or equal to 2 g/m2 per one surface. (2) The hot-dip zinc-based plated steel sheet according to (I), wherein the surface treatment layer fi~rther contains at least one of one or rnore phosphorus-containing compounds, one or more vanadium-containing compounds, 5 one or more copper-containing compounds, one or more aluminum-containing compounds, one or more silicon-containing compounds, or one or more chromiumcoritaining conlpounds in the following range as a content per one surface, the one or more phosphorus-containing compounds: more than or equal to 0.0 g/~n2an d less than or equal to 0.01 g/tn2 on a P basis, 10 the one or more vanadium-containing compounds: more than or equal to 0.0 g/m2 and less than or equal to 0.01 g/m2 on a V basis, the one or more copper-containing compounds: more than or equal to 0.0 g/m2 and less than or equal to 0.02 g/m2 on a Cu basis, the one or more aluminum-containing compounds: more than or equal to 0.0 15 g/n12 and less than or equal to 0.005 g/m2 on anA1 basis, the one or more silicon-containing compounds: more than or equal to 0.0 g/m2 and less than or equal to 0.005 g/m2 on a Si basis, and the one or more chromium-containing compounds: more than or equal to 0.0 g/mn2 and less than or equal to 0.01 g/n12 on a Cr basis. 20 (3) The hot-dip zinc-based plated steel sheet according to (1) or (2), wherein the particle size of each of the one or more oxides selected from zirconia, lanthanum oxide, cerium oxide, and neodymium oxide is more than or equal to 10 nln and less than or eqnal to 200 nm. 25 (4) The hot-dip zinc-based plated steel sheet according to any one of (1) to (3), v~herein the content of the one or more oxides selected fio~n zirconia, lanthanum oxide, cerium oxide, and neodymium oxide is more than or equal to 0.4 g/m2 and less 30 than or equal to 1.5 g/m2 per one surface. (5) The hot-dip zinc-based plated steel sheet according to any one of (1) to (4), wherein the one or more oxides include zirconia or lanthanum oxide. (6) 5 The hot-dip zinc-based plated steel sheet according to any one of (1) to (5), wherein the surface treatment layer further contains one or tnore oxides selected kom titanium oxide, nickel oxide, and tin(1V) oxide each having a particle size of more than or equal to 2 nm and less than or equal to 100 nm, in a range of more than 10 or equal to 0.2 dm2 and less than or equal to 2 g/m2 per one surface. (7) The hot-dip zinc-based plated steel sheet according to (6), wherein the particle size of each of the one or more oxides selected fsom titanium oxide, nickel oxide, and tin(W) oxide is more than or equal to 5 nm and less than or 15 equal to 50 nm. (8) The hot-dip zinc-based plated steel sheet according to (6) or (7), wherein the content of the one or more oxides selected from titanium oxide, nickel oxide, and tin(IV) oxide is more than or equal to 0.4 g/m2 and less than or equal to 20 1.5 g/m2 per one surface (9) The hot-dip zinc-based plated steel sheet according to any one of (6) to (8), wherein the one or more oxides include titanium oxide. 25 (10) The hot-dip zinc-based plated steel sheet according to any one of (I) to (9), wherein the surface treatment layer further contains magnesium oxide, calcium oxide, or zinc oxide in a range of tnore than or equal to 0.2 g/m2 and less than or equal to 30 5.0 g/m2 per one surface. (11) The hot-dip zinc-based plated steel sheet according to (lo), wherein the particle size of the magnesium oxide, the calcium oxide, or the zinc oxide is more than or equal to 5 nm and less than or equal to 100 nm. (12) The hot-dip zinc-based plated steel sheet according to (10) or (ll), wherein the content of the magnesium oxide, the calcium oxide, or the zinc oxide is iiiore than or equal to 0.4 g/m2 and less than or equal to 2.5 g/m2 per one surface. (13) The hot-dip zinc-based plated steel sheet according to any one of (1) to (12), 10 wherein the hot-dip zinc-based plated steel sheet is a hot-dip zinc-based plated steel sheet for hot pressing. Advar~tageousE ffects of Invention 15 [0021] As described above, according to the present invention, it becomes possible to improve the coating adhesivetless to a coating film provided after hot pressing. Description of Embodiments 20 [0022] . Hereinafter, preferred embodiments of the present illventiori are described in detail. [0023] 4. Hot-dip zinc-based plated steel sheet> 25 A hot-dip Zn-based plated steel sheet according to an embodiment of the present invention includes a hot-dip Zn-based plating layer on a ground steel sheet, and further includes a surface treatment layer described in detail below on at least one surface of the hot-dip Zn-based plating layer. The surface treatment layer contains one or Inore oxides selected from zirconia, lanthanum oxide, cerium oxide, 30 and neodymium oxide each liaving a particle size of more than or equal to 5 nm and less than or equal to 500 mn, in a range of more than or equal to 0.2 g/m2 and less than or equal to 2 g/n~2pe r one surface. The hot-dip Zn-based plated steel sheet having such a configuration can be suitably used for the hot pressing method described above. Hereinafter, the configuration of the hot-dip Zn-based plated steel slieet will be described in detail. 5 [0024] (1) Ground steel sheet The ground steel sheet used for the hot-dip Zn-based plated steel sheet according to the present embodiment is not particularly limited, and various steel sheets ilaving known characteristics and chemical compositions may be used. The 10 chemical composition of the steel sheet is not particularly limited, but is preferably a chemical composition with which high strength is obtained by quenching. For example, when it is attempted to obtain a heat-treated steel material with a tensile strength of 980 MPa or more, an example of the ground steel sheet is made of steel for quenching having a chemical co~npositiono f, in mass%, C: 0.05 to 0.4%, Si: less 15 than or equal to 0.5%, Mn: 0.5 to 2.5%, P: less than or equal to 0.03%, S: less than or equal to 0.01%, sol. Al: less than or equal to 0.1%, N: less than or equal to 0.01%, B: 0 to 0.005%, Ti: 0 to 0.1%, Cr: 0 to 0.596, Nb: 0 to O.l%, Ni: 0 to 1.O%, Mo: 0 to 0.5%, and the balance: Fe and impurities. [0025] 20 When it is attempted to obtain a heat-treated steel material with a relatively low strength in which the strength becomes less thali 980 MPa during quenching, the chemical conlposition of the ground steel sheet is not uecessarily be in the range described above. [0026] 25 The total amoullt of mi and Cr contained is preferably 0.5 to 3.0% from tlie viewpoint of quenchability during the quenching described above and the viewpoint of forming Mn oxides and Cr oxides contained in a zinc oxide layer after heating. The total amount of Mn and Cr contained is more preferably 0.7 to 2.5%. [0027] 30 When Mn and Cr are contained as the chemical composition of the steel sheet, part of the zinc oxide layer formed on the outer layer after hot pressing becomes co~nposite oxides containing Mn and Cr. Coating adliesiveness after phosphate-based chemical conversion treatment is fi~rtlier improved by these composite oxides containing Mn and Cr being formed. Although details are unknown, it is presumed that, by these composite oxides being formed, the alkali 5 resistance of the phosphate-based chemical conversion treatment coating film formed is improved as compared to zinc oxide, and good coating adhesiveness is exhibited. [0028] In the case where Mn and Cr are contained as the chetnical cotnposition of the steel sheet, the content of Mn and Cr is preferably in the range of, in mass%, 10 more than or equal to 0.5% and less than or equal to 3.0%, and Inore preferably in the range of, in mass%, more than or equal to 0.7% and less than or equal to 2.5%. In the case where the content of Mn+Cr is less than 0.5%, zinc oxide that is fornied on the outer layer after hot pressing and composite oxides that eontairi Mn and Cr are insufficient, and it may be difficult to bring out more satisfactoly coating 15 adhesiveness. On the other hand, in the case where the content of Mn+Cr exceeds 3.0%, although there is no problem with coating adhesiveness, the cost is increased, and fiulhermore the toughness of the spot welded portion may be significantly reduced and the wettability of plating may be significantly degraded. [0029] 20 (2) Hot-dip Zn-based plating layer The hot-dip Zn-based plating layer according to the present embodiment is not particularly limited, and comrno~lly known zinc-based plating tnay be used. Specifically, examples of the hot-dip Zn-based plating layer according to the present embodiment include hot-dip galvanizing, alloyed hot-dip galvanizing, Zn-55%Al 25 plating, Zn-11%Al plating, Zn-11%Al-3%Mg plating, Zn-7%A1-3%Mg plating, and Zn-ll%Al-3%Mg-O,2%Si plating. Note that, as described above, A1 is contained even in the hot-dip galvanizing and the alloyed hot-dip galvanizing. [0030] In the present emboditnent, as a specific dip plating operation, an operation 30 in which a steel sheet is dipped in a plating bath in which Zn or a Zn alloy in a molten state is retained and the steel sheet is pulled up fron~ the plating bath is performed. Tlie amount of plating attached to the steel sheet is controlled by adjusting the speed of the pulling-up of the steel sheet, the flow rate and the flow velocity of wiping gas jetted from a wiping nozzle provided above the plating bath, etc. Alloying treatment is performed by, after plating treatment like the above, 5 additionally heating the plated steel sheet using a gas furnace or an induction heating furnace, a heating furnace in which these are combined, or the like. The plating operation may also be pel-fornled by the method of continuously plating a coil or the method of plating a cut sheet single body. [0031] 10 The thickness of the hot-dip Zn-based plating layer (that is, the amount of the hot-dip Zn-based plating layer attached) is preferably in the range of 20 g/m2 to 100 g/m2 per one surface. In the case where the thickness of the hot-dip Zn-based plating layer is less than 20 g/m2 per one surface, the effective amount of Zn after hot pressing cannot be ensured and corrosion resistatice is insufficieiit; thus, this is not 15 preferable. In the case where the thickness of the hot-dip Zn-based plating layer is more than 100 g/m2 per one surface, the processability and the adhesiveness of the hot-dip Zn-based plating layer are reduced; thus, this is not preferable. A more preferred thickness of the hot-dip Zn-based plating layer is in the range of 30 g/m2 to 90 g/in2 per one surface. 20 [0032] (3) Surface tseatment layer On the hot-dip Zn-based plating layer, there is fkrther formed a surface treatn~ent layer containing one or more oxides selected from zirconia (ZrOz), lanthanum oxide, cerium oxide, and neodymium oxide. 25 [0033] Here, "zirconia" represents a substance that contains oxide of zirconium (2s) as a main component, which exists in a state of being dispersed in a treatliient liquid as a solid having a size of several nanometers or Inore as a primary pat-ticle size, and does not exist in a state of being dissolved in the treatment liquid like a~n~~ionisuarlnt, 30 potassiutn salt, sodium salt, and the like of zirconium carbonate, zirconiutn nitrate, zirconium sulfate, and the like. Using the zirconia being dispersed in a treatment liquid as a solid, it becomes possible to provide a heat-treated steel ~nateriael xcellent in durability even in an environment of dipping in salt water. [0034] Note that the one or more oxides selected from zirconia, lanthanum oxide, 5 cerium oxide, and neodymium oxide exist in a state of pal-ticles in the sutface treatment layer. [0035] To he specific, the above-mentioned granular zirconia, latlthanum oxide, cerium oxide, and neodymium oxide each have a particle size (primary particle size) 10 of more than or equal to 5 nm and less than or equal to 500 nm. For the particle size of zirconia, lanthanum oxide, cerium oxide, and neodymium oxide, a smaller size is advantageous it1 terms of post-coating corrosiotl resistance, but those with a particle size of less than 5 nm are difficult to obtain and are disadvantageous in terms of cost. Further, in the case where the particle size of zirconia, lanthanum oxide, 15 cerium oxide, and neodymium oxide exceeds 500 nm, a contact area of zirconia, lanthanum oxide, cerium oxide, and neody~niur~oix ide with the plated steel sheet decreases, and an influence given to the steel sheet by the zirconia particle decreases during heating in hot pressing; thus, this is not preferable. The particle size of zirconia, latlthanuln oxide, cerium oxide, and neodymiu~n oxide is preferably more 20 than or equal to 10 nm and less than or equal to 200 nm. [0036] The particle size (primary particle size) of the zirconia, lanthanum oxide, cerium oxide, and neodymium oxide described above can be measured by a known method; for example, the measurement can be performed by a method in which a 25 cross section-embedded sample is prepared after coating, several particle sizes of zirconia, lanthanum oxide, cerium oxide, and neodymium oxide in the coating filtn are measured, and the average of the obtained measurement results is taken as the particle size. 100371 30 The surface treatment layer included in the hot-dip Zn-based plated steel sheet according to the present ernbodirr~ent contains one or more selected fiotn zirconia, lanthanuin oxide, cerium oxide, and neodymium oxide each having the above-mentioned primary particle size in the range of more than or equal to 0.2 g/~n2 and less than or equal to 2 g/m2 per one surface. When the content of the one or more selected from zirconia, lanthanum oxide, cerium oxide, and neodymium oxide 5 in the surface treatment layer is in the range of more than or equal to 0.2 g/m2 and less than or equal to 2 g/m2 per one surface, during heating, zirconia, lanthanu~n oxide, cerium oxide, or neody~iiiurn oxide in the surface treatment layer makes harmless an A1 oxide that is present before hot pressing and is formed during hot pressing. Thereby, the formation of zinc oxide during hot pressing is accelerated; 10 thus, phosphate treatability after hot pressing is enhanced, and coating adhesiveness is improved. Although details of the fact that an A1 oxide is made harmless during heating by zirconia, lanthanum oxide, cerium oxide, or neodymium oxide are unknown, it is presumed that zirconia, lanthanum oxide, cerium oxide, or neodymium oxide dissolves an Al oxide formed on the surface of the steel sheet, 15 thereby Zn, which is relatively easy to oxide after Al, is oxidized during hot pressing, and consequently the production of zinc oxide (ZnO), which is excellent in chemical conve~tibilityi, s accelerated. [0038] When the amount of the one or more selected from zirconia, lanthanum 20 oxide, cerium oxide, and ~leodymium oxide contained in the surface treatment layer is less than 0.2 g/m2 per one surface, sufficient zirconia, lanthanum oxide, cerium oxide, and neodymium oxide are not present after hot pressing; consequentl~: the effect of making harmless an A1 oxide of the plated surface is reduced, and coating adhesiveness after hot pressing cannot be sufficiently ensured. On the other hand, 25 when the amount of zirconia contained in the surface treatment layer is more than 2 g/m2 per one surface, the cost of the Zn-based hot-dipped steel sheet according to the present embodiment is increased, and it is presutned that the cohesive force of the surface treatment layer is weakened and a coating film that is formed on the surface treatment layer after hot pressing is likely to peel off. 30 [0039] The amount of the one or no re selected from zirconia, lanthanum oxide, cerium oxide, and neodyminm oxide contained in the surface treatment layer is preferably more than or equal to 0.4 g/m2 and less than or equal to 1.5 g h 2 per one surface. [0040] 5 Typical exarnples of the treatment liquid containing zirconia, lanthanutll oxide, cerium oxide, and neodytnium oxide include a zirconia sol, a lanthat~utno xide sol, a cerium oxide sol, and a neodymium oxide sol, and specific examples of the comnlercially available product include NanoUse (registered trademark) series manufactured by Nissat~ Chemical Industries, Ltd. and Ceramase series 10 manufactured by Taki Chemical Co., Ltd. [0041] In forming the surface treatment layer, the above-mentioned zirconia sol, lanthanum oxide sol, cerium oxide sol, and neodymium oxide sol may be applied as they are to the hot-dip Zn-based plated steel sheet, however, in order to improve 15 stability of the treatment liquid and adhesiveness of the surface treatment layer, it is more preferred that the treatment liquid have a resin or a crosslinking agent mixed therein, and the treatment liquid be applied to the hot-dip Zn-based plated steel sheet. 100421 In the case where the above zirconia sol, lanthanum oxide sol, cerium oxide 20 sol, and neodymium oxide sol are used, a water-soluble or water-dispersible resin is preferably used as the resin, and examples of the resin include a polyurethane resin, a polyester resin, at1 epoxy resin, a ,(meth)actylic resin, a polyolefin resin, a phenol resin, and ~nodified products of those resins. In the case where zirconia powder is used, a solvent resin in which any of various solve~itsi s used as the solvent may be 25 used in addition to the above-mentioned water-based resin. [0043] Examples of the crosslinking agent include a zirconium carbonate compound, an organic titanium compound, all oxazoline polymer, a water-soluble epoxy compound, a water-soluble melamine resin, a water-dispersible blocked 30 isocyanate, and a water-based aziridine comnpound. [0044] Examples of the other component that is preferably further contained in the surface treatment layer according to the present embodiment include one or more selected from titanium oxide, nickel oxide, and tin(1V) oxide. [0045] 5 When the one or more selected from titanium oxide, nickel oxide, and tin(1V) oxide mentioned above are contained in the surface treatment layel; tliese oxides are present on the surface of the steel sheet after hot pressing; thereby, some influence is given to the cohesion deposition of an electrodeposition coating film during electrodeposition coating, and the oxides and the electrodeposition coating 10 film adhere strongly; thus, strong adhesiveness can be exhibited even when chemical conversion treatment (phosphate treatment or FF chemical conversion treatment) is not sufficient. To obtain this effect inore efficiently, the particle size of the oxide mentioned above is preferably more than or equal to 2 nm and less than or equal to 100 nm. 15 [0046] In addition, atnong these oxides, titanium oxide not only has the feature mentioned above but also can suppress excessive oxidation and vaporization of Zn during hot pressing, and can enhance not only coating adhesiveness after hot pressing but also corrosion resistance after hot pressing. It is surmised that titanium oxide 20 usually exists in a state of a metal oxide stably, but reacts with zinc oxide formed during heating in hot pressing and forms a composite oxide with zinc oxide, and thereby suppresses excessive oxidation and vaporization of Zn. To obtain this effect more efficiently, the particle size of titanium oxide mentioned above is preferably more than or equal to 2 nnl and less than or equal to 100 nm. 25 [0047] The pai-ticle size of the one or more selected from titanium oxide, nickel oxide, and tin(1V) oxide mentioned above is more preferably more than or equal to 5 ~ IanId less than or equal to 50 nnt. [0048] 30 In the case where the s~~rfatcrea tment layer contains titanium oxide, nickel oxide, and tin(1V) oxide, these are contained preferably in the range of more than or equal to 0.2 g/tn2 and less than or equal to 2 g/~n2p er one surface, and more preferably in the range of more than or equal to 0.4 g/tn2 and less than or equal to 1.5 g/m2 per one surface. When the content of titanium oxide, nickel oxide, and tin(1V) oxide is less than 0.2 g/m2 per one surface, these oxides are not present sufficiently 5 after hot pressing, and consequently it may be difficult to bring out still better adhesiveness to the electrodeposition coating film. [0049] On the other hand, when the content of titanium oxide, nickel oxide, and tin(W) oxide is more than 2 gh2 per one sorface, the cost of the Zn-based plated 10 steel sheet according to the present e~nbodimenits increased, and it is presumed that the cohesive force of the surface treatment layer is weakened and a coating film that is formed on the surface treatment layer after hot pressing is likely to peel off. [0050] In addition to the above, when the content of titanium oxide is less than 0.2 15 g/m2 per one surface, a sufficient amount of a composite oxide with zinc oxide cannot be formed, and it may be difficult to efficiently suppress the oxidation and vaporization of Zn. [005 11 Fui-thel; examples of the other component that is preferably fi~rther 20 contained in the surface treatment layer according to the present embodiment include magnesium oxide, calcium oxide, or zinc oxide. [0052] When the surface treatment layer contains the above-mentioned magnesium oxide, calcium oxide, or zinc oxide, those oxides are present on the outer layer of the 26 surface treatment layer after hot pressing; and thus, phosphate treatability is improved. As a reason for the improvement in phosphate treatability, it is presumed that the chemical conversion reaction with a phosphate or the like is accelerated by magnesium oxide being dissolved in the phosphate treatment liquid. To obtain this effect more efficiently, the particle size of each of the above-mentioned magnesium 30 oxide, calcium oxide, or zinc oxide is preferably more than or equal to 5 lun and less than or equal to 100 nm, and more preferably more than or equal to 10 mn atid less than or equal to 50 nm. [0053] In the case where the surface treatment layer contains magnesium oxide, calcium oxide, or zinc oxide, the content thereof is preferably in the range of more 5 than or equal to 0.2 g/m2 and less than or equal to 5 g/1~12p er one surface, and more preferably more than or equal to 0.4 g/1112 and less than or equal to 2.5 g/m2 per one surface. In the case where the coiiterit of niagtiesium oxide, calcium oxide, and zinc oxide is less than 0.2 g/m2 per one surface, since those oxides are not sufficiently present after hot pressing, it may be difficult to exhibit satisfactoty phosphate 10 treatability. On the other hand, in the case where the content of magnesium oxide, calcium oxide, and zinc oxide exceeds 2 g/m2 per one surface, the cost of the Znbased plated steel sheet according to tlie present embodiment is increased, atid it is presumed that the cohesive force of tlie surface treatment layer is weakened and a coating film that is formed on the surface treatment layer after hot pressing is likely 15 to peel off. [0054] The surface treatment layer according to the present embodiment nnay contain, in addition to oxides like the above, at least one of one or more P-containing compounds, one or more V-containing compou~ids, one or inore Cu-containing 20 conlpounds, one or more Al-containing compounds, one or more Si-containing compounds, and one or more Cr-containing connpounds described in detail below in the range of a predetermined content. [OOSS] The P-containing compound is a coinpound containing phosphorus as a 25 constituent element. Examples of the P-containing compound include compounds such as phosphoric acid, phosphorous acid, phosphonic acid, phosphonous acid, phosphinic acid, phosphinous acid, a phosphine oxide, and phospliine, an ionic compound containing any of these conipounds as an anion, and the like. All tliese P-containing coinpounds are commercially available as reagents or products, and can 30 be easily obtained. These P-containing cotnpounds exist in a state of being dissolved in a treatment liquid or in a state of being dispersed as powder in a treatment liquid, and exist, in the surface treatment layel; in a state of being dispersed as solid. [0056] The V-containing compound is a compound containing vanadium as a 5 constituent element. Exa~nples of the V-containing co~npound include vanadium oxides such as vanadium pentoxide, metavauadic acid-based compounds such as ammonium metavanadate, vanadium conlpounds such as sodium vanadate, and other V-containing compounds. Those V-containing compounds are corn~nercially available as reagents or products, and can be easily obtained. Those V-containing 10 compounds exist in a state of being dissolved UI a treatment liquid or in a state of being dispersed as powder in a treatment liquid, and exist, in the surface treatment layer, in a state of being dispersed as solid. [0057] The surface treatment layer according to the present embodiment preferably 15 contains one or more compounds selected from one or more P-containing compounds and one or more V-containing compoulids mentioned above individually in the range of more than or equal to 0.0 g/m2 and less than or equal to 0.01 g/m2 per one surface on a P and V basis. [OOSS] 20 One or more cotnpounds selected from one or more P-contai~iitig compounds and one or more V-containing compounds mentioned above are oxidized into an oxide during hot pressing, and the oxide exists locally at the interface between the hot-dip Zn-based plating layer and the surface treatment layer and forms an oxide layer that contains at least one of P and V and has weak cohesive force. 25 Since the content of the one or more compounds selected from one or more Pcontaining cornpou~ids and one or more V-containing compounds contained is individually in the range of Inore than or equal to 0.0 g/m2 and less than or equal to 0.01 g/m2 per one surface on a P and V basis, the thickness of an oxide layer like the above that is formed during hot pressing and has weak collesive force is reduced, and 30 the adhesiveness between the hot-dip Zn-based plating layer and the surface treatnler~lta yer after hot pressing is further improved. [0059] In the case where the content of the one or more selected fiom one or more P-containing compounds and one or more V-containing compounds in the surface treatment layer exceeds 0.01 g/ln2 per one surface, the thickness of the oxide layer 6 that is formed during hot pressing and has weak cohesive force is increased; consequently, the adhesiveness between the hot-dip Zn-based plating layer and the surface treatment layer is reduced, and as a result also adhesiveness after electrodeposition coating is reduced. From the viewpoint of the adhesiveness between the hot-dip Zn-based plating layer and the surface treatment layer after hot 10 pressing, the content of the one or more co~npounds selected fsom one or more Pcontaining compounds and one or more V-containing compounds in the surface treatment layer is more preferably individually more than or equal to 0.0 g/m2 and less than or equal to 0.003 g/1n2 per one surface on a P and V basis. [0060] 15 The Cu-containing compound is a compound containing copper as a I constituent element. Examples of the Cu-containing compound include metal Cu, copper oxide, various organic copper compounds, various inorganic copper compounds, arid various copper complexes. Those Cu-containing compounds are commercially available as reagents or products, and can be easily obtained. Those 20 Cu-containing colnpounds exist in a state of being dissolved in a treatment liquid or in a state of being dispersed as powder in a treatment liquid, and exist, in the surface treatment layer, in a state of being dispersed as solid. [0061] The surface treatment layer according to the present embodimetit preferably 25 contains one or more con~pounds selected from one or more Cu-containing compounds mentioned above in the range of more than or equal to 0.0 g/m2 and less than or equal to 0.02 dm2 per one surface on a Cu basis. LO0621 One or Inore colnpounds selected from one or more Cu-containing 30 compounds mentioned above are oxidized into an oxide during hot pressing, and the oxide exists locally at the interface between the hot-dip Zn-based plating layer and the surface treattnent layer and forms an oxide layer that contains Cu and has weak cohesive force. Since the content of the one or tnore compounds selected fiom one or more Cu-containing compounds is in the range of more than or equal to 0.0 g/m2 and less than or equal to 0.02 g/m2 per one surface on a Cu basis, the thickness of an 5 oxide layer like the above that is fortned during hot pressing and has weak cohesive force is reduced, and the adhesiveness between the hot-dip Zn-based plating layer and the surface treatment layer after hot pressing is further improved. [0063] 111 tlie case where the content of the one or more selected fiom one or more 10 Cu-containing colnpol~nds in the surface treatment layer exceeds 0.02 g/m2 per one surface, the thickness of the oxide layer that is fornied during hot pressing and has weak cohesive force is increased; consequently, the adhesiveness of the interface between the hot-dip Zn-based platiug layer and the surface treatment layer is reduced, and as a result, also adhesiveness after electrodeposition coating is reduced. 111 15 addition, since Cu is an element nobler than Fe, which is a main component of the ground steel sheet, also the corrosiotl resistance tends to decrease. From the viewpoit~t of tile adhesiveness between the hot-dip Zn-based plating layer and the surface treatment layer after hot pressing, the content of the one or more cotnpounds selected fiom one or more Cu-containing compounds in the surface treatment layer is 20 more preferably more than or equal to 0.0 g/m2 and less that1 or equal to 0.005 g/tn2 per one surface 011 a Cu basis. [0064] The Al-containing compound is a compoutid containing aluminurn as a constituent element. Examples of the Al-containing con~pound include metal Al, 25 aluminuln oxide, aluminum hydroxide, an ionic compound containing an aluminutn ion as a cation, and the like. Those Al-containing cotnpounds are comtnercially available as reagents or products, and can be easily obtained. Those Al-containing compounds exist in a state of being dissolved in a treatment liquid or in a state of being dispersed as powder in a treatment liquid, and exist, it1 the surface treatment 30 layel; in a state of being dispersed as solid. [0065] The Si-containing compound is a compound containing silicon as a constituent element. Examples of the Si-containing compound include Si simple substance, silica (silicon oxide), organic silane, a silicone resin used also as a binder resin, and other Si-containing compounds. All these Si-containing compounds are 5 con~mercially available as reagents or products, and can be easily obtained. These Si-containing compounds exist in a state of being dissolved in a treatment liquid or in a state of being dispersed as powder in a treatment liquid, and exist, in the surface treattnerit layer, in a state of being dispersed as solid. [0066] 10 The surface treatment layer according to the present embodiment preferably contains one or more conlpounds selected from one or more Al-containing compounds and one or tnore Si-containing compounds like the above individually in the lange of more than or equal to 0.0 g/m2 and less than or equal to 0.005 ghn2 per one surface on an Al and Si basis. 15 [0067] One or more cotnpounds selected from one or more Al-containing compounds and one or more Si-containing compounds like the above are oxidized into an oxide during hot pressing, and the oxide concentrates on the surface of the surface treatment layer. Since the amount of the one or more compounds selected 20 from one or more Al-containing compounds and one or more Si-containing compounds contained is individually in the range of more than or equal to 0.0 gin? and less than or equal to 0.005 g/m2 per one surface on an Al and Si basis, the existence ratio of the oxides containing Al or Si that are formed on the surface of the surface treatment layer during hot pressing is reduced, and the adhesiveness between 25 the surface treatment layer and the electrodeposition coating film after hot pressing is further improved. [0068] In the case where the content of the one or more selected from one or more Al-containing conlpounds and one or more Si-containing con~pounds in the surface 30 treatment layer is more than 0.005 g/m2 per one surface, the existence ratio of the oxides containing A1 or Si that are fornled during hot pressing is increased. These oxides containing A1 or Si inhibit the formation of a chemical conversion treatment coating film, and reduce the adhesiveness between the surface treatment layer and the elcct~~odepositiocno ating film after hot pressing; therefore, when the existence ratio of the oxides containing A1 or Si that are formed during hot pressing is 5 increased, the adhesiveness between the surface treatment layer and the electrodeposition coating film is reduced. From the viewpoint of the adhesiveness between the surface treatment layer and the electrodeposition coating film afier hot pressing (that is, post-coating adhesiveness), the amount of the one or more compounds selected from one or more Al-containing compounds axid one or more Si- 10 containing compounds contained in the surface treatment layer is tnore preferably individually more than or equal to 0.0 g/m2 and less than or equal to 0.002 g/m2 per one surface on an Al and Si basis. [0069] The Cr-containing compound is a compound containing chromium as a 15 constituent element. Examples of the Cr-containing co~npound include metal Cr, chromium compounds having various valences, and an ionic compound containing a chromium ion having any of various valences as a cation. Those Cr-containing compounds exist in a state of being dissolved in a treatment liquid or in a state of beitig dispersed as powder in a treatment liquid, and exist, in the surface treatment 20 layer, in a state of being dispersed as solid. [0070] The Cr-containing conlpound varies in performance and propel-ties in accordance with the valence, and many hexavalent chromium co~npounds are harnlfi~l. In view of the current tendency of attention to environmental protection 25 being strongly required, the surface treatment layer according to the present embodiment preferably contains as little amount of Cr-containing compounds mentioned above as possible, and is more preferably chromium-free. [0071] The Cr-containing compound varies in performarice and properties in 30 accordance with the valence, and many hexavalent chromium compounds are harmfill. In view of the current tendency of attention to environmental protection being strongly required, the surface treatment layer according to the present embodiment preferably contains as little amount of Cr-containing compounds like the above as possible, and is more preferably chro~nium-free. [0072] 5 The surface treatment layer may contain pigments such as carbon black and titania, various anti-corrosive particles used for coated steel sheets, and the like as long as the effect of the present invention based on containing one or more selected fiom zirconia, lanthanum oxide, cerium oxide, and rleodymiu~no xide is not inhibited. Also in this case, the surface treatment layer contains the granular zirconia atld the 10 like in the range of more than or equal to 0.2 g/m2 and less than or equal to 2 g/n12 per one surface. [0073] Addition of those pigments does not directly improve coating film adhesiveness and corrosion resistance after hot pressing, however, the pigments such 15 as carbon black and titania increases emissivity on the surface of the steel sheet during hot press heating in a furnace; and thus can shorten the heating time. The anti-corrosive particles can suppress corrosion of the steel sheet before hot press heating. [0074] 20 As the method for forming the surface treatment layer, a treatment liquid containing one or more selected fiom granular zirconia, lanthanum oxide, cerium oxide, and neodymium oxide may be applied to the surface of a zinc-plated steel sheet, and drying and baking may be performed. I00751 25 The coating method is not limited to a specific method, and examples include a method in which a ground steel sheet is dipped in a treatment liquid or a treatment liquid is sprayed to the surface of a ground steel sheet, and then the attached amount is controlled by a roll or gas spraying so as to obtain a prescribed attached amount, and a tnethod of coating using a roll coater or a bar coater. 30 [0076] The method of drying and baking is not limited to a specific method, eithel; as long as it is a method that can volatilize a dispersion medium (mainly water). Here, if heating is performed at an excessively high temperature, it is feared that the uniformity of the surface treatment layer will be reduced; conversely, if heating is performed at an excessively low temperature, it is feared that productivity will be 5 reduced. Thus, to produce a surface treatment layer having excellent characteristics stably and efficiently, the surface treatment layer after coating is preferably heated at a temperature of approximately 80°C to 150°C for approximately 5 seconds to 20 seconds. [0077] 10 The formation of the surface treatment layer is preferably performed in-line in the production line of the plated steel sheet because this is economical; but the surface treatment layer may be formed also in another line, or may be formed after blanking for molding is performed. [0078] 15 Here, the content of zirconia, lanthanum oxide, cerium oxide, neodymium oxide, titanintn oxide, nickel oxide, tin(lV) oxide, magnesium oxide, calcium oxide, and zinc oxide in the surface treatment layer can be measured by a known method; for example, the fact that the various compounds are zirconia or an oxide of an alkaline-earth metal is checked beforehand by cross-sectional energy dispersive X- 20 ray (EDX) analysis or the like, and then the coating film is dissolved; thus, the measurement can be made using inductively coupled plasma (ICP) emission spectrometric analysis or the like. Also, the content of the above-mentioned one or more P-containing compounds, V-containing compounds, Cu-containing con~pounds, Al-containing compounds, Si-containing compounds, and Cr-containing compounds 25 contained in the surface treatment layer can be measured by a similar method. [0079] <2. Regarding hot pressing process> In the case where the hot pressing method is uscd for a hot-dip Zn-based plated steel sheet like that described above, the hot-dip Zn-based plated steel sheet is 30 heated to a prescribed temperature, and is then press-molded. In the case of the hotdip Zn-based plated steel sheet according to the present embodiment, heating is usually performed to 700 to 1000°C because liot press molding is perfosn~edb; ut in the case where a n~astensite single phase is formed after rapid cooling or nlartensite is fornied at a volume ratio of 90% or more, it is important that the lower lirnit of the heating temperature be the Ac, point or more. In the case of the present invention, 5 also the case where a two-phase region of mal-tensite/ferrite is fornled after rapid cooling is included, and therefore the heating temperature is preferably 700 to 1000°C as described above. [OOSO] Examples of the hot pressing tnethod include two methods of hot pressing 10 by slow heating and hot pressing by sapid heating. Exan~pleso f the heating method used include heating with an electric furnace or a gas furnace, flame heating, energization heating, high-freqriency heating, and induction heating, and the atmosphere during heating is not pa~*icularly limited; as a heating method to obtain the effect of the present invention significantly, energization heating, induction 15 heating, and the l i e , which are rapid heating, are preferably used. [0081] In the hot pressing method by slow heating, the radiation heating of a heating furnace is used. First, the hot-dip Zn-based plated steel sheet according to the present embodiment that is used as a steel sheet for hot pressing is placed in a 20 heating furnace (a gas furnace, an electric filmace, or the like). The steel sheet for hot pressing is heated at 700 to 1000°C in the heating furnace, and is, depending on the condition, kept at this heating temperature (soaking). Thereby, molten Zn in the hot-dip Zn-based plating layer is combined with Fe and forms a solid phase (Fe-Zn solid solution phase). After the tnolten Zn in the hot-dip Zn-based plating layer is 25 combined with Fe and forms a solid phase, the steel sheet is taken out of the heating fnrnace. Alternatively, by combining molten Zn in tlie hot-dip Zn-based plating layer with Fe by soaking, the solid phase may be formed as an Fe-Zn solid solntion phase and a ZnFe alloy phase; and then the steel sheet may be taken out of the heating fi~rnace. 30 COO821 Alternatively, the hot-dip Zn-based plated steel sheet may be heated to 700 to 1000°C while no keeping tiine is provided or tlie keeping time is set to a slioit time, and the steel sheet niay be taker1 out of the heating furnace. In this case, after the steel sheet is heated to 700 to 1000°C, cooling is performed without applying stress to the steel sheet by press molding or the like until hot-dip Zn in the hot-dip 5 Zn-based plating layer is co~nhined with Fe and forms a solid phase (Fe-Zn solid solution phase or ZnFe alloy phase). Specifically, cooling is performed until at least the temperature of the steel sheet becomes lower than or equal to 782OC. After the cooling, as described below, cooling is performed while the steel sheet is pressed using a mold. 10 [0083] Also in hot pressing by rapid heating, similarly, the hot-dip Zn-based plated steel sheet according to the present embodiment that is used as a steel sheet for hot pressing is rapidly heated to 700 to 1000°C. The rapid heating is performed by, for example, energization heating or induction heating. The average heating rate in this 15 case is 20"CIsecond or more. In the case of rapid heating, after the hot-dip Znbased plating layer is heated to 700 to 1000°C, cooling is performed without applying stress to the steel sheet by press molding or the like until hot-dip Zn in the hot-dip Zn-based plated steel sheet is conihined with Fe and forms a solid phase (Fe- Zn solid solution phase or ZnFe alloy phase). Specifically, cooling is performed 20 until at least the temperature of the steel sheet becotnes lower than or equal to 782OC. After the cooling, as described below, cooling is performed while the steel sheet is pressed using a mold. [0084] The taken-out steel sheet is pressed using a mold. When pressing the steel 25 sheet, the steel sheet is cooled by the mold. A cooling medium (for example, water or tlie like) is circulated through the mold, and the mold removes heat from the steel sheet atid cools it. By the above process, a hot pressed steel material is produced by normal heating. [OOSS] 30 The hot pressed steel material produced using the hot-dip Zn-based plated steel sheet including the surface treatment layer according to the present embodiment has excellent phosphate treatability and coating adhesiveness. In particular, the hotdip Zn-based plated steel sheet according to the present embodiment exhibits the effect significantly in the case where heating is performed at 700 to 1000°C by hot pressing by rapid heating or lot pressing by slow heating while no keeping time is 5 provided or the keeping time is set to a short time. [0086] In the case where hot pressing by nornlal heating is perfortned using a conventional plated steel sheet, the steel sheet is soaked in a heating furnace. In this case, although an A1 oxide film is formed on tlie outer layer of the plating layer of the 10 steel sheet for hot pressing, the Al oxide film is broken and divided to some degree due to long time soaking, and therefore the adverse effect on chemical conversion treatability is small. On the other hand, in the case where hot pressing by rapid heating is performed, the soaking time is very short. Hence, the A1 oxide film formed on the outelmost surface is less likely to be broken. Thus, in hot pressing 15 by rapid heating in the case where a conventional plated steel sheet is used, the phosphate treatability and the coating adhesiveness of the hot pressed steel material are low as compared to hot pressing by normal heating. [OOS7] On the other hand, the hot-dip Zn-based plated steel sheet for hot pressing 20 according to the present embodinlent contains one or more selected from zirconia, lanthanum oxide, cerium oxide, and neodymium oxide in the surface treatment layer, and thereby makes the A1 oxidization harmless and accelerates the production of zinc oxide during hot pressing; and can thus exhibit good phosphate treatability and coating adhesiveness. 25 [Exanlples] [0088] The action and effect of the hot-dip Zn-based plated steel sheet accordiug to an embodiment of tlie present invention will now be described still more specifically with reference to Examples. Examples shown below are only examples of the hot- 30 dip Zn-based plated steel sheet according to the present invention, and the hot-dip Zn-based plated steel sheet according to the present invention is not limited to Exatnples below. [0089] In the following, first, pieces of molten steel having the chemical 5 co~npositions shown in Table 1 below were produced. After that, the produced pieces of molten steel were used to produce slabs by the contitmous casting method. The obtained slab was hot rolled to produce a hot rolled steel sheet. Subsequently, the hot rolled steel sheet was pickled, and then cold rolling was performed to produce a cold rolled steel sheet; thus, steel sheets of steel #I to #8 having the chenlical 10 compositions described in Table 1 were prepared. As shown in Table 1, the sheet thicknesses of the steel sheets of all the steel types were 1.6 trim. [0090] [Table 11 [0091] The steel sheets of steel #1 to #8 were subjected to hot-dip galvanizing treatment, and were then subjected to alloying treatment. With the maximum 5 temperature in each alloying treatment set to 53ODC, heating was perfornied for approxilnately 30 seconds; and then cooliug was performed to room temperature; thus, an alloyed hot-dip galvanized steel sheet (GA) was produced. Using steel #1, hot-dip galvanizing treatment was performed, and a hot-dip galvanized steel sheet (GI) was produced without performing alloying treatment. 10 [0092] Further, steel #1 was subjected to various types of hot-dip galvanizing using three types of plating baths of molten Zn-55%A1, molten Zn-6%Al-3%Mg, and molten Zn-lI%Al-3%Mg-0.2%Si, and hot-dip zinc-based plated steel sheets A1 to A3 were produced. 15 Al: molten Zn-%%A1 A2: molten Zn-6%A1-3%Mg A3: molten Zn-ll%A1-3%Mg-0.2%Si [0093] Note that the A1 concentration in the plating coating film of the hot-dip Zn- 20 based steel sheet described above was found by the following method. That is, a sample was collected from each hot-dip Zn-based plated steel sheet. The hot-dip Zn-based plating layer of the collected sample was dissolved in a 10% HCI aqueous solution, and the cornposition of the hot-dip Zn-based plating layer was analyzed by ICP emission spectrometric analysis. The A1 concentration (mass%) per one 25 surface was determined on the basis of the obtained analysis result. The obtained results are collectively shown in Table 3 below. [0094] Subsequently, in order to prepare a chemical solution having the 30 con~positions shown in Table 2 in a solid content ratio, the following oxides and chen~ical agents were blended using water. The obtained treatment liquid was applied with a bar coater, aud drying was performed using an oven under conditions for keeping a maximum peak temperature of 100°C for 8 seconds; thus, a plated steel sheet for hot pressing was produced. The amount of the treatment liquid attached was adjusted by the dilution of the liquid and the count of the bar coater so that the 5 total amount of attached nonvolatile content in the treatment liquid might be the numerical value shown in Table 3. In Table 2 below, the solid content concentration of each component is written as the ratio of the nonvolatile content of each component, such as "oxide A," to the nonvolatile content of the entire treatment liquid (nnit: mass%). 10 [0095] The components (symbols) in Table 2 are as follows. As described later, also a treatment liquid containing alumina (sol) was investigated as granular substances other than zirconia, lanthanum oxide, cerium oxide, and neodymium oxide; in this case, alumina is denoted by "oxide A". 15 Similarly, titanium oxide, nickel oxide, and tin(1V) oxide are denoted by "oxide B", and magnesium oxide, calcium oxide, and zinc oxide are denoted by "oxide C". [0096] (Oxide A) zirconia, lanthanum oxide, cerium oxide, neodymium oxide, and alumina ZB: a zirconia sol (NanoUse (registered trademark) ZR-40BL, manufactured by Nissan Chemical Industries, Ltd.), particle size: 70 to 110 nm (catalog value) ZA: a zirconia sol (NanoUse (registered trademark) ZR-30AL, ~nanufactured by Nissan Chemical Industries, Ltd.), particle size: 70 to 110 run 25 (catalog value) ZP: zirconia powder (zirconium oxide manufactured by KOJUNDO CHEMICAL LABORATORY CO., LTD., particle size: approximately 1 pm La: a lanthanum oxide sol (Biral La-C10, manufactured by Taki Chemical Co., Ltd.), particle size: 40 nm (catalog value) 30 Ce: a cerium oxide sol (Needlal P-10, manufactured by Taki Chemical Co., Ltd.), particle size: 20 ntn (catalog value) Nd: a neodytniurn oxide sol (Biral Nd-ClO, manufactured by Taki Chemical Co., Ltd.), particle size: 40 tun (catalog value) AZ: an alumina sol (Aluminasol 200, mariufactur~d by Nissan Chemical Industries, Ltd.), particle size: approxitnately 10 nm 5 [0097] (Oxide B) titaniutn oxide, nickel oxide, and tin(1V) oxide Ti: titania sol (titania sol TKS-203, manufactured by Tayca Corporation), particle size: approximately 6 nnl Ni: nickel oxide (nickel oxide, manufactured by IoLiTec GmbH), particle 10 size 20 nm Sn: tin(1V) oxide sol (Ceratl~aseC -10, manufactured by Taki Chemical Co., Ltd.), particle size: 10 ntn [0098] (Oxide C) magnesium oxide, calcium oxide, and zinc oxide 15 Mg: magnesium oxide (manufactured by IoLiTec GmbH), particle size: 35 nm (catalog value) Ca: calciurn oxide (manufach~redb y Kanto Chemical Co.,Inc.) *Used after being dispersed in resin-added water and pulverizing pignient with a ball mill. 20 Zn: zinc oxide (manufactured by IoLiTec GmbH), particle size: 20 nm (catalog value) [0099] (iii) Resin A: a urethane-based resin e~nulsion (Superflex (registered trademark) 150, 25 manufactured by DKS Co. Ltd.) B: a urethane-based resin en~ulsion (Superflex (registered trademark) E- 2000, manufactured by DKS Co. Ltd.) C: a polyester resin emulsion (Vylonal (registered trademark) MD1480, manufactured by Toyobo Co., Ltd.) 30 [OlOO] (iv) Crossli~lkinga gent M: a melamine resin (Cy111el ((registered trademark) 325, manufactured by Mitsni Cytec Ltd.) Z: ammonium zirconiuln carbonate (an alnmoniu~n zirconium carbonate solution, manufactured by Kishida Chemical Co.,Ltd.) 5 S: a silane coupling agent (Sila-Ace S510, ma~mfacturedb y Nichibi Trading Co.,LTD.) (a Si-containing compound) [OlOl] (v) Pigment CB: carbon black (Mitsubishi (registered trademark) carbon black #1000, 10 manufactured by Mitsubishi Chemical Corporation) T: titanium oxide (titanium oxide R-930, lnanufactured by Ishihara Sangyo Kaisha, Ltd.), particle size: 250 nnl (catalog value) "T" titanium oxide described herein is a pigment with a particle size of 200 to 400 nm mnai~lly used for a white pigment or the like in a coating material, and 15 cannot achieve performance obtained by oxide B because the particle size is larger than that of (oxide B). PA: condensed A1 phosphate (condensed aluminum phosphate, K-White ZFl SOW, manufactured by Tayca Corporation) (a P and Al-containing compound) PZ: zinc phosphite (M'-530, manufactured by Toho Gal~yoC o., Ltd.) (a P- 20 containing compound) Sil: silica paiticles'(~~1ornas0k2 , manufactured by Fuji Silysia Chemical Ltd.) (a Si-containing compound) Si2: colloidal silica (Snolvtex 0, manufactured by Nissan Chemical Industries, Ltd.) (a Si-containing cotnpound) 25 AL: an alumina sol (AS-200, manufactured by Nissan Chemical Industries, Ltd.) (an Al-containing compound) V: potassium vanadate (a general reagent) (a V-containing compound) Cr: Cr(V1) oxide (a general reagent) (a Cr-containing conlpound) Cu: copper(I1) oxide (a general reagent) (a Cu-containing compound) [O 1 021 [Table 21 Table 2-5 Concantrotion [0 1071 [Table 71 After the formation process of the surface treatment layer, the steel sheet of each test number was subjected to hot press heating by two types of heating systems 5 of filmace heating and energization heating, and thus hot pressing was performed. In the furnace heating, the atmosphere in the furnace was set to 910°C and the airfuel ratio was set to 1.1, and the steel sheet was taken out of the furnace immediately after the temperature of the steel sheet reached 900°C. In the energization heating, heating was performed at 870°C, with the heating rate set to 85°C/second and 10 42.5"C/second. In the following, the results of energization heating, which is heating of a shot-ter time than furnace heating, are shown in Table 3, and the results by furnace heating are shown in Table 4. [0109] After the hot press heating, cooling was performed until the temperature of 15 the steel sheet became 650°C. After the cooling, the steel sheet was sandwiched by a flat sheet mold equipped with a water cooling jacket, and thus a hot pressed steel material (steel sheet) was produced. Cooling was pel-formed up to approximately 360°C, which is the martensite transformation starting point, so as to ensure a cooling rate of 50°C/second or more even in a portion where the cooling rate had 20 been low during the hot pressing, and thus quenching was performed. [OllO]