FIELD OF THE INVENTION
This invention relates to biodegradable films, fabrics made of knitted, woven
or nonwoven fabrics and laminates. Herein, the knitted, woven and nonwoven
fabrics are preferably but not limited to be biodegradable.
5
BACKGROUND OF THE INVENTION
In the past 20 years, polylatic acid (PLA) has become a leading
biodegradable/compostable polymer for preparation of plastics and fibers. This is
because although the PLA is derived from natural and renewable materials, it is
10 also thermoplastic and can be melt extruded to produce plastic items, fibers and
fabrics with good mechanical strength and pliability comparable to oil-based
synthetics such as polyolefins (polyethylene and polypropylene) and polyesters
(polyethylene terephthalate and polybutylene terephthalate). PLA is made from
lactic acid, which is a fermentation byproduct obtained from corn (e.g. Zea mays),
15 wheat (e.g. Triticum spp.), rice (e.g. Oryza sativa), or sugar beets (e.g. Beta
vulgaris). When polymerized, the lactic acid forms a dimer repeat unit with the
following structures:
Unlike other synthetic fiber materials (such as cellulosics) originated from
20 plant, PLA is more suited for melt spinning into fibers. Compared to the
solvent-spinning process required for synthetic cellulosic fibers, PLA fiber made
by adoption of melt spinning allows for lower economic cost and environmental
3
cost, and the resulting PLA has a wider range of properties. Like polyethylene
terephthalate polyester (PET), PLA polymer needs to be dried before melting to
avoid hydrolysis during melt extrusion, and fiber from both polymers can be drawn
(stretched) to develop better tensile strength. The PLA molecule tends to form a
helical structure which brings about easier crystallization. Also the lactic dimer ha5 s
three kinds of isomers: an L form which rotates polarized light in a clockwise
direction, a D form which rotates polarized light in a counter-clockwise direction
and a racemic form which is optically inactive. During polymerization, the relative
proportions of these forms can be controlled, resulting in relatively broad control
10 over important polymer properties. The control over a thermoplastic “natural” fiber
polymer, unique polymer morphologies and the isomer content in the polymer
enables the manufacturer to design a relatively broad range of properties in the
fiber (Dugan, J. S. 2001, “Novel Properties of PLA Fibers”, International
Nonwovens Journal, 10 (3): 29-33; Khan, A.Y.A., L.C. Wadsworth, and C.M.
15 Ryan, 1995, “Polymer-Laid Nonwovens from Poly(lactide) Resin”, International
Nonwovens Journal, 7: 69-73).
PLA is not considered to be directly biodegradable in its extruded state.
Instead, it must first be hydrolyzed before it becomes biodegradable. In order to
achieve hydrolysis of PLA at significant levels, both a relative humidity at or
20 above 98% and a temperature at or above 60°C are required simultaneously. Once
these conditions are met, degradation occurs rapidly (Dugan, J. S. 2001, “Novel
Properties of PLA Fibers”, International Nonwovens Journal, 10 (3): 29-33 and
Lunt, J. 2000, “Polylactic Acid Polymers for Fibers and Nonwovens”,
International Fiber Journal, 15: 48-52). However, the melt temperature can be
25 controlled between about 120°C and 175°C so as to control the content and
arrangement of the three isomers, in which case the polymer is completely
amorphous under the low melting temperature. Some more amorphous polymers
4
can be obtained after the addition of enzymes and microbes in the melt.
PLA has been used to make a number of different products, and factors that
control its stability and degradation rate have been well documented. Both the
L-lactic acid and D-lactic acid produced during fermentation can be used to
produce PLA (Hartmann, M.H., 1998, “High Molecular Weight Polylactic Aci5 d
Polymers”, p. 367-411, In: D.L. Kaplan (ed.), Biopolymers from Renewable
Resources, Springer-Verlag, New York). One advantage of PLA is that the
degradation rate can be controlled by altering factors such as the proportion of the
L and D forms, the molecular weight or the degree of crystallization (Drumright,
10 R.E., P.R., Gruber, and D.E. Henton, 2000, “Polylactic Acid Technology,”
Advanced Materials. 12: 1841-1846). For instance, Hartmann (1998) finds that
unstructured PLA sample will rapidly degrade to lactic acid within weeks, whereas
a highly crystalline material can take months to years to fully degrade. This
flexibility and control make PLA a highly advantageous starting material in the
15 production of agricultural mulch fabrics, where the PLA material is intended to be
degraded in the field after a specific time period (Drumright, R.E., P.R., Gruber,
and D.E. Henton, 2000, “Polylactic Acid Technology,” Advanced Materials. 12:
1841-1846).
PLA is decomposed into smaller molecules through a number of different
20 mechanisms, and the final decomposition products are CO2 and H2O. The
degradation process is influenced by temperature, moisture, pH value, enzyme and
microbial activity while keeping free of being affected by ultraviolet light
(Drumright, R.E., P.R., Gruber, and D.E. Henton, 2000, “Polylactic Acid
Technology,” Advanced Materials. 12: 1841-1846; Lunt, 2000). In some early
25 work that evaluated PLA degradation for biomedical applications, Williams (1981)
finds that bromelain, pronase and proteinase K can accelerate the decomposition
rate of PLA (Williams, D.F., 1981, “ Enzymic Hydrolysis of Polylactic Acid,”
5
Engineering in Medicine. 10: 5-7). More recently, Hakkarainen et al. (2000)
incubate PLA sample of 1.8 millimeter thickness at 86°F in a mixed culture of
microorganisms extracted from compost (Hakkarainen, M., S. Karlsson, and A.C.
Albertsson, 2000., “Rapid (Bio)degradation of Polylactide by Mixed Culture of
Compost Microorganisms - Low Molecular Weight Products and Matrix Changes”5 ,
Polymer. 41: 2331-2338). After 5 weeks of incubation, the compost-treated film
has degraded to a fine powder, whereas the untreated control remains intact. It is
noted that this study uses only the L form while the degradation rate will differ
based on the ratio of the D and L forms. Regardless, the work by Hakkarainen et al.
10 (2000) illustrates that application of large quantities of readily available
microorganisms from compost can accelerate the decomposition. Yet the PLA
degradation studies so far are either performed in liquid culture in vitro or in active
composting operations above 140°F (Drumright et al., 2000; Hakkarainen et al.,
2000; Lunt, 2000; Williams, 1981). Rapid degradation occurs when PLA is
15 composted at 140°F with nearly 100% biodegradation achieved in 40 days
(Drumright et al., 2000). However, the stability below 140°F when the fabric is in
contact with soil organic matter remains to be determined. Spunbond (SB) and
meltblown (MB) nonwovens using PLA are first researched by Larry Wadsworth
(Khan et al., 1995) at the University of Tennessee, USA (Smith, B.R., L.C.
20 Wadsworth (Speaker), M.G. Kamath, A. Wszelaki, and C.E. Sams, “Development of
Next Generation Biodegradable Mulch Nonwovens to Replace Polyethylene
Plastic,” International Conference on Sustainable Textiles (ICST 08), Wuxi, China,
October 21-24, 2008[CD ROM]).
It is desirable for biodegradable polymers to resist many environmental
25 factors during application period, but to be biodegradable under disposal
conditions. The biodegradation of PLA is studied in both aerobic and anaerobic,
aquatic and solid state conditions at different elevated temperatures. It is found that
6
in aerobic aquatic exposure, PLA biodegrades very slowly at room temperature but
faster under thermophilic conditions. This also supports the findings above that
PLA must be hydrolyzed before microorganism can utilize it as a nutrient source.
The biodegradation of PLA is much faster in anaerobic solid state conditions than
that in aerobic conditions at the same elevated temperatures. In a natura5 l
composting process, the behavior of PLA is similar to the aquatic biodegradation
exposure, in which biodegradation only starts after it is heated up. These results
reinforced a widely held view that PLA is compostable and is stable under room
temperature, but degrades rapidly during disposal of waste in compost or anaerobic
10 treatment facilities (Itavaara, Merja, Sari Karjomaa and Johan-Fredrik
Selin,“Biodegradation of Polylactide in Aerobic and Anerobic Thermophilic
Conditions,” Elsevier Science Ltd., 2002). In another study, the biodegradation
levels of different plastics by anerobic digested sludge are determined and
compared with those in simulated landfill conditions. Bacterial poly
15 93-hydroxyvalerate (PHB/PHV), natural aliphatic polyester produced by bacteria,
almost completely degrades in 20 days in anaerobic digested sludge; whereas, PLA,
the aliphatic polyester synthesized from natural materials, and two other aliphatic
polyesters evaluated, poly (butylenes succinate) and poly (butylenes
succinate-co-ethylene succinate) fail to degrade after 100 days. A cellulosic control
20 material (cellophane) degrades in a similar way to that of PHB/HV within 20 days.
Furthermore, PHB/HV degrades well within 6 months in simulated landfill
conditions (Shin, Pyong Kyun, Myung Hee Kim and Jong Min Kim,
“Biodegradability of Degradable Plastics Exposed to Anaerobic Digested Sludge
and Simulated Landfill Conditions,” Journal of Polymers and the Environment,
25 1566-2543, Volume 5, Number 1, 1997).
In the search for truly biodegradable polymer, polyhydroxyalkonates (PHAs)
have been found to be naturally synthesized by a variety of bacteria as an
7
intracellular storage material of carbon and energy. As early as the 1920s,
poly[(R)-3-hydroxybutyrate] (P(3HB)) is isolated from Bacillus megaterium and
identified later as a microbial reserve polyester. However, P(3HB) does not have
important commercial value since it is found to be brittle and stiff over a long
period and thus cannot be substituted for the mainstream synthetic polymers lik5 e
polyethylene (PE) and polystyrene (PS). Eventually, the discovery of other
hydroxalkonate (HA) units other than 3HB in microbial polyesters which can
improve the mechanical and thermal properties when incorporated into P(3HB)
have a major impact on research and commercial interests of bacterial polyesters.
10 Their biodegradability in natural environment is one of the unique properties of
PHA material. The microbial polyester is biodegradable in soil, sludge or sea water.
Since PHA is a solid polymer with high molecular weight, it cannot be transported
through the cell wall as a nutrient. Thus, the microorganisms such as fungi and
bacteria excrete an enzyme knows as PHA degrading enzyme for performing
15 extracellular degradation on PHA. Such enzyme hydrolyzes the solid PHA into
water soluble oligomers and monomers, which can then be transported into the cell
and subsequently metabolized as carbon and energy sources (Numata, Keiji, Hideki
Abe and Tadahisa Iwata, “Biodegradability of Poly(hydroxalkonate) Materials,”
Materials,2, 1104-1126, 2009). A random copolyester of [R[-3-hydroxybutyrate
20 and [R]-3-hydroxyvalerate, P(3HB-co-3HV), is commercially produced by
Imperial Chemical Industries (ICI) in the UK. It is shown that Alcaligenes
eutrophus produces an optically active copolyester of 3-hydroxybutyrate (3HB)
and 3-hydroxyvalerate (3HV) by using propionic acid and glucose as the carbon
sources (Holmes, PA, (1985), “Applications of PHB: a Microbially Produced
25 Biodegradable Thermoplastic,” Phys Technol 16:32-36 from Kunioka, Masao,
Yasushi Kawaguchi and Yoshiharu Doi, “Production of Biodegradable
copolyesters of 3-hydroxybutyrate and 4-hydroxybutyrate by Alcaligenes
8
eutropus,” Appl. Microbiol Biotechnol (1989) 30: 569-573). The chemical
structure for P(2HB-co-3HV) is as follows:
Furthermore, 3-hydroxypropionate, 4-hydroxyvutyrate, and
4-hydroxyvalerate are found to be new constituents of bacteria5 l
polyhdroxyalkonates (PHAs) and have gained much attention in a wide range of
marine, agricultural and medical applications. More recently, the microbial
synthesis of copolyesters of [R]-3-hydroxybutyrate and 4-hydroxybutyrate,
P(3HB-co-4HB), by Alcaligenes eutropus, Comamonas and Alcaligens latus have
10 been studied. The chemical structure of P(3HB-co-4HB) is as follows:
When 4-hydroxybutyric acid is used as the only carbon source for Alcaligenes
eutrophus, P(3HB-co-34% 4HB) is produced with the content of 34% 4HB, while
4-hydroxybutyric acid in the presence of some additives is used as the carbon
15 source for Alcaligenes eutrophus, P(3HB-co-4HB) copolyester with a large portion
of 4HB (60-100 mol%) is produced. It has also been found that Alcaligenes
eutrophus produces a random copolymer of P(3HB-co-4HB) with high efficiency
in a one stage fermentation process by the usage of sucrose and 1,4-butyrolactone
as the carbon source in a nitrogen free environment. The tensile strength of
20 P(3HB-co-4HB) film decreases from 43MPa to 26 MPa while its elongation
increases from 4-444% with the increasing content of 4HB fraction. On the other
hand, as the content of 4HB fraction increases from 64% to 100%, the tensile
strength of the film increases from 17MPa to 104 Mpa with the increase of 4HB
(Saito, Yuji, Shigeo Nakamura, Masaya Hiramitsu and Yoshiharu Doi, “Microbial
9
Synthesis and Properties of Poly(3-hydroxybutyrate-co-4-hydroxybutyrate),”
Polymer International 39 (1996), 169-174). Some studies show that the degree of
crystallinity of P(3HB-co-4HB) decreases from 55% to 14% as the content of 4HB
fraction increases from 0 to 49 mol%, indicating that 4HB unit cannot crystallize in
the sequence of 3HB unit and acts as the defect in the P(3HB) crystal lattice. Thi5 s
is probably largely responsible for the reduced brittleness and improved toughness
of P(3HB-co-4HB) compared to P(3HB). Also the melting temperature is found to
decrease from 178°C to 150°C as the content of 4HB fraction increases from 0 to
18 mol% (Kunioka, Masao, Akira Tamaki and Yoshiharu Doi, Crystalline and
10 Thermal Properties of Bacterial copolyesters:
Poly(3-hydroxybutyrate-co-3-hydroxvalerate) and
Poly(3-hydroxybutyrate-co-4-hydroxybutyrate),” Macromolecules 1988, 22,
694-697). It has also been shown that the biodegradation rate is increased by the
presence of 4HB unit in P(3HB-co-4HB) (Kunioka, Masao, Yasushi Kawaguchi
15 and Yoshiharu Doi, “Production of Biodegradable copolyesters of
3-hydroxybutyrate and 4-hydroxybutyrate by Alcaligenes eutropus,” Appl.
Microbiol Biotechnol (1989) 30: 569-573). In another study, the enzymatic
degradation of P(3HB-co-4HB) film is performed at 37 °C in a 0.1 M phosphate
buffer of extracellular depolymerase purified from Alcaligenes faecalis. It is then
20 found that the rate of enzymatic degradation notably increases with the increasing
content of 4HB fraction and the highest rate occurs at 4HB of 28 mol% (Nakamura,
Shigeo and Yoshiharu Doi, “Microbial Synthesis and Characterization of
Poly(3-hydroxybutyrate-co-4hydroxybutyrate),” Macromolecules, 85 (17),
4237-4241, 1992).
25 This may be due to the resultant decrease in crystallinity; whereas, the
presence of 4HB in excess of 85 mol% in the copolyester suppresses the enzymatic
degradation (Kumaai, Y. Kanesawa, and Y. Doi, Makromol. Chem., 1992, 193, 53
10
through Nakamura, Shigeo and Yoshiharu Doi, “Microbial Synthesis and
Characterization of Poly(3-hydroxybutyrate-co-4hydroxybutyrate),”
Macromolecules, 85 (17), 4237-4241, 1992). In a comparison of the
biodegradation rates of P(3HB-co-9% 4HB), P(3HB) and P(HB-co-50% 3HV)
films, the P(3HB-co-9% 4HB) is found to be completely degraded in activate5 d
sludge in two weeks with the degradation rate of this biopolyester being much
faster than those of the other two. The degradation rate of P(3HB) is much faster
than that of P(HB-co-50% 3HV) film (Kunioka, Masao, Yasushi Kawaguchi and
Yoshiharu Doi, “Production of Biodegradable copolyesters of 3-hydroxybutyrate
10 and 4-hydroxybutyrate by Alcaligenes eutropus,” Appl. Microbiol Biotechnol
(1989) 30: 569-573).
Polybutylene adipate terephthalate (PBAT) is a biodegradable polymer which
is currently synthesized from oil-based products rather than from bacteria.
Although PBAT has a melting point of 120 °C which is lower than that of PLA, it
15 has high flexibility, excellent impact strength and good melt processibility.
Furthermore, several studies about the biodegradation of PBAT film and molded
product have indicated that significant biodegradation occurs in one year in soil,
sea water and water with activated sludge. On contrary, even though PLA has good
melt processibility, strength and biodegradation/composting properties, it has both
20 low flexibility and low impact strength. At this point, the flexibility, softness and
impact strength of the final product can be improved by mixing PBAT with PLA.
Some studies show that the least compatible blending ratio of PBAT and PLA is
50/50. However, it has been shown that miscibility and thus the mechanical
property of a 50/50 blend of PBAT and PLA are improved by applying ultrasound
25 energy to the melt blend with an ultrasonic device for 20 to 30 seconds. In this
study, tensile strength is found to increase with increasing sonication time.
Specifically, tensile strength reaches the highest value up to 20 seconds and then
11
decreases after 20 seconds, whereas impact strength increases up to 30 seconds and
then decreases over time after that point. However, sonicated system is found to
have much higher impact strength than that of an un-sonicated system. It is
explained that excess energy is consumed by the plastic deformation of PBAT
phase in sonicated system, while propagating stress passes around the PBA5 T
phases since they are immiscible and separated in the untreated system. This can be
seen from a scanning electron microscopy (SEM) that, a minimum domain size of
4.7 μm is achieved after 30 seconds of sonication but notably increased with time
afterwards. It is concluded that the excess energy leads to the flocculation of
10 domain (Lee, Sangmook, Youngjoo Lee and Jae Wook Lee, “Effect of Ultrasound
on the Properties of Biodegradable Polymer blends of Poly(lactic acid) with
Poly(butylene adipate-co-terephthalate,” Macromolecular Research, Vol. 15, No. 1,
pp 44-50 [2007]). As pointed out above, PBAT has excellent elongation at break of
above 500%. On contrary, the elongation at breaks are only 9% and 15% for PLA
15 and PHBV (“Biodegradable polyesters: PLA, PCL, PHA”…,
http://www.biodeg.net/bioplastic.html). Therefore, in addition to increasing the
flexibility, extensibility and softness of film, packaging material and fabric made
by blending PBAT with PLA or PHA, a laminate with good extensibility can be
produced by the lamination of PBAT film into elastic biodegradable or
20 non-biodegradable fabrics. The chemical structure of PBAT is shown below:
PBAT is available commercially from BASF as Ecoflex™, Eastman Chemical
as Easter Bio®, and from Novamont of Italy as Origo-Bi®. DuPont is marketing a
biodegradable aromatic copolyester known as Biomax®. However, rather than
25 PLA, it is a modified poly(ethylene terephthalate) with a high content of terephtalic
acid and a high temperature of about 200 °C. Like PLA, Biomax® must firstly
12
undergo hydrolysis before biodegradtion, which begins with small molecules being
assimilated and mineralized by some microorganisms existed in the nature
(Vroman, Isabelle and Lau Tighzert,”Biodegradable Polymers,” Materials 2009, 2,
307-344). In 2004, Novomont purchased the Eastar Bio copolyester business from
Eastman chemical Company (“Novamont buys Eastman’s Eastar Bio technology5 ”
http://www.highbeam.com/doc/1G1-121729929.html). BASF notes that its PBAT,
Ecoflex™ is highly compatible with natural materials such as starch, cellulose,
lignin, PLA and PHB (“Bio – Sense or Nonsense, “ Kunstoffe International 8/2008
[Translated from Kunstoffe 8/2008, pp. 32-36).
10 Poly(butylenes succinate) PBS and its copolymer belong to the
poly(alkenedicarboxylate) family. They are synthesized by polycondensation
reaction of glycol (such as ethylene glycol and 1,4-butanediol) with aliphatic
dicarboxylic acid (like succinic acid or adipic acid). They are marketed in Japan by
Showa High Polymer as Bionolle® and in Korea by Ire Chemical as EnPol®.
15 Different alkenedicarboxylates that have been produced are PBS, poly(ethylene
succinate) (PES) and a copolymer prepared by the addition of adipic acid
poly(butylene succinate-co-adipate) or PBSA. In addition, a copolymer made by
the reaction of 1,2-ethylenediol and 1,4 butanediol with succinic and adipic acids
has been marked in Korea by SK Chemical as Skygreen®. Another alipahatic
20 copolyester sold by Nippon Shokubai of Japan is known as Lunare SE®. PBS is a
crystalline polymer with a melting point of 90-120 °C and a glass transition
temperature (Tg) of about -45 °C to -10 °C. The PBS has the Tg value between
those of polyethylene (PE) and polypropylene (PP), and it has similar chemical
properties to those of PE and PP. Besides, the PBS has a tensile strength of 330
kg/cm2 25 and an elongation-to-break of 330%, while its procssibility is better than
that of PLA (Vroman, Isabelle and Lau Tighzert,”Biodegradable Polymers,”
Materials 2009, 2, 307-344). The chemical structure of PBS is shown below:
13
PBS consisted of succinic acid may also be produce by bacteria. At this point,
bio-based succinic acid is used by Sinoven Biopolymers of China to produce PBS
with a renewable content of 50%. It is reported that this kind of PBS has better
performances than any other biodegradable polymers and has a heat resistanc5 e
above 100°C (“Production of Bio-based polybutylene succinate (PBS)”,
http://biopol.free.fr/index.php/production-of-biobased-polybutylene-succinate-pbs/
). PBS is blended with PLA to improve flexural properties, heat distortion
temperature, impact strength and gas permeability. Herein, PBS can be miscible
10 with PLA and reduce the brittleness of PLA when the concentration of PBS is less
than 20% (Bhatia, Amita, Rahul K. Gupta, Sati N. Bhattacharya and H.J. Choi,
“Compatibility of biodegradable poly (lactic acid) (PLA) and poly (butylenes
succinate) (PBS) blends for packaging application,” Korea-Australia Rheology
Journal, November 2007, Vol. 19, No. 3, pp. 125-131).
15
SUMMARY OF THE INVENTION
The technical problem to be solved in this invention is to provide
biodegradable film and laminate which have extended shelf life in clean
environment and accelerated degradation in dirty environment, aiming at the
20 drawbacks that the degradation rate of the existing biodegradable material is low.
In this invention, the technical solution adopted to solve its technical problem
is as follows: biodegradable film is constructed. This film comprises PHAs and
PLA, wherein the content of PLA is 1%-95% in mass percent.
Blend of PHAs and PLA which enables enhanced biodegradation property is
25 made of PHAs-PLA.
14
In a preferred embodiment of this invention, the product made from the blend
of PHAs and PLA has extended shelf life in clean environment.
In a preferred embodiment of this invention, the product made from the blend
of PHAs and PLA can be configured for producing film, container for solid and
liquid, rigid or flexible package, woven, knitted and non-woven fabric wit5 h
filament and staple fiber, and composite product of fabric and film through thermal
forming, injection molding or melt spinning.
In a preferred embodiment of this invention, non-woven fabrics made by melt
spinning comprise spunbond and meltblown non-woven fabrics.
10 In a preferred embodiment of this invention, non-woven fabrics bonded by
wet adhesive or dry adhesive include carding and air laying.
In a preferred embodiment of this invention, non-woven fabrics are bonded by
wet adhesive such as latex or dry adhesive such as thermal bonding power or fiber.
In a preferred embodiment of this invention, non-woven fabrics are obtained
15 by needlepunching, hydroentangling, thermal calendaring, hot air through-air
thermal bonding or the following heating processes including microwave,
ultrasonic wave, welding, far infrared heating and near infrared heating.
In a preferred embodiment of this invention, the fabrics comprise the
laminates made by spunbond, spunbond-spunbond, spunbond-meltblown and
20 spunbond-meltblown-spunbond which can be used for industrial protective
clothing, medical protective clothing such as hospital operating room drape and
gown fabric, sterile instrument wrap, patient lifting sling and patient stretcher.
In a preferred embodiment of this invention, composite fabric is the laminate
of film and fabric which is made in combination with other non-woven production
25 processes such as spun laying, needlepunching and air laying of pulp or fiber as
well as hydroentangling.
In a preferred embodiment of this invention, the laminate includes meltblown
15
air filter media, meltblown liquid filter media and spunbond or other types of
non-woven fabrics as outer and inner facings, wherein the facings only need to be
sewn or thermally or ultrasonically bonded on their edges.
In a preferred embodiment of this invention, the composites include MB PLA
and blend of MB PLA with PHAs and with cellulosic fiber, such as pulp, shor5 t
cotton fiber or other manmade or natural fibers added to the meltblown fiber
stream or in layers between MB layers.
In a preferred embodiment of this invention, the PHAs are PHBs or PHVs, or
a copolymer or blend of PHBs and PHVs.
10 In a preferred embodiment of this invention, the PHBs are P(3HB-co-4HB)
polymerized by 3HB and 4HB.
In a preferred embodiment of this invention, the mole percent of 4HB ranges
from 5% to 85%.
In a preferred embodiment of this invention, the percentage of PLA in dry
15 blend or in composite and melt extruded blend of PHAs range from 1% PLA to
95% PLA, preferably at or below 50% PLA and most preferably at or below 30%
PLA (50%-10%).
In a preferred embodiment of this invention, biodegradable and compostable
woven, knitted and non-woven fabrics as well as film product have improved
20 mechanical properties, elongation-to-break, flexibility and impact resistance when
the blend of PBAT and PLA include PBAT of 5-60% and preferably PBAT of
20-40%.
In a preferred embodiment of this invention, biodegradable and compostable
woven, knitted and non-woven fabrics as well as film product have improved
25 mechanical properties, elongation-to-break, flexibility and impact resistance when
the blend of PBS and PLA include PBS of 5-40% and preferably PBS of 10-40%.
In a preferred embodiment of this invention, biodegradable and compostable
16
woven, knitted and non-woven fabrics as well as film product have improved
mechanical properties, elongation-to-break, flexibility and impact resistance when
the blend of PBAT, PBS and PLA include PBAT of 5-50% and PBS of 5-40%, and
preferably include PBAT of 10-30% and PBS of 10-40%.
In a preferred embodiment of this invention, PBAT film has improved strength5 ,
decreased thermal shrinkage and lower cost by blending with 10-60% PLA and
preferably with 20-40% PLA.
In a preferred embodiment of this invention, PBAT film has improved
strength, decreased thermal shrinkage and lower cost by blending with 10-60%
10 PBS and preferably with 20-40% PBS.
In a preferred embodiment of this invention, PBAT film has improved
strength, decreased thermal shrinkage and lower cost by blending with 10-40%
PLA and 10-40% PBS, and preferably with 15-30% PLA and 15-30% PBS.
In a preferred embodiment of this invention, the preceding biodegradable and
15 compostable woven, knitted and non-woven fabrics and film product have reduced
cost when blended with fillers such as starch and calcium carbonate in amounts
ranging from 5 to 60% and preferably from 10 to 40%.
In a preferred embodiment of this invention, the preceding biodegradable and
compostable PBAT film has reduced cost when blended with fillers such as starch
20 and calcium carbonate in amounts ranging from 5 to 60% and preferably from 10
to 40%.
In a preferred embodiment of this invention, knitted, woven or non-woven
fabrics made of PLA by addition of fillers such as starch and calcium carbonate in
amounts ranging from 5 to 60% and preferably from 10 to 40% are lower in cost.
25 In a preferred embodiment of this invention, knitted, woven and non-woven
fabrics made of blends of PLA and PHA by addition of fillers such as starch and
calcium carbonate in amounts ranging from 5 to 60% and preferably from 10 to
17
40% are lower in cost.
In a preferred embodiment of this invention, films made of PBS by addition of
fillers such as starch and calcium carbonate in amounts ranging from 5 to 60% and
preferably from 10 to 40% are lower in cost.
In a preferred embodiment of this invention, the preceding biodegradable an5 d
compostable fabrics can be laminated to obtain laminate.
In a preferred embodiment of this invention, laminates consisted of the
respective biodegradable and compostable fabrics can be adhesively bonded
through biodegradable glue or heat-melt adhesive.
10 In a preferred embodiment of this invention, the fabrics are used as crop
mulch films to suppress weed growth, enhance moisture control, increase soil
temperature and reduce fertilizer leaching.
In a preferred embodiment of this invention, the films are used as crop mulch
films to suppress weed growth, enhance moisture control, increase soil temperature
15 and reduce fertilizer leaching.
In a preferred embodiment of this invention, the fabric and film laminates may
be used as crop mulch films to suppress weed growth, enhance moisture control,
increase soil temperature and reduce fertilizer leaching.
In a preferred embodiment of this invention, the preceding laminates may be
20 used for patient lifting slings and patient stretchers.
In a preferred embodiment of this invention, the laminates may be used in
disposable diapers and feminine sanitary napkins.
In a preferred embodiment of this invention, the laminates are made of
PBAT-based film and elastomer meltblown or spunbond non-woven fabric; the
25 elastomer meltblown or spunbond non-woven fabric is made of ExxonMobil
Vistamaxx® containing 100% Vistamaxx or blends of 60-95% Vistamaxx with
other polymers such as polypropylene (PP).
18
In a preferred embodiment of this invention, the laminates are made of
PBAT-based film and elastomer meltblown or spunbond non-woven fabric; the
elastomer meltblown or spunbond non-woven fabric is made of ExxonMobil
Vistamaxx® containing 100% Vistamaxx or blends of 60-95% Vistamaxx with
other polymers such as polypropylene (PP). Herein, the laminates are bonded wit5 h
glue or hot-melt adhesives.
In a preferred embodiment of this invention, the laminates are made of
PBAT-based film and elastomer meltblown or spunbond non-woven fabric; the
elastomer meltblown or spunbond non-woven fabric is made of ExxonMobil
10 Vistamaxx® containing 100% Vistamaxx or blends of 60-95% Vistamaxx with
other polymers such as polypropylene (PP). Herein, the laminates are thermally
bonded.
In a preferred embodiment of this invention, the laminates are made of
PBAT-based film and elastomer meltblown or spunbond non-woven fabric; the
15 elastomer meltblown or spunbond non-woven fabric is made of ExxonMobil
Vistamaxx® containing 100% Vistamaxx or blends of 60-95% Vistamaxx with
other polymers such as polypropylene (PP). The PBAT film is extrusion-coated on
the Vistamaxx.
This invention discloses enhanced biodegradable fabric and laminate which
20 may be produced by laminating biodegradable film. The biodegradable film may
primarily consist of polybutylene adipate terephthalate (PBAT) or polybutylene
succinate (PBS) or blends of PBAT and PBS with polylactic acid (PLA) and other
biodegradable polymers such as polybutylene succinate adipate (PBSA),
polycaprolactone (PCL), polycaprolactone butylene succinate (PCL-BS) and
25 polydyroxyalkonates (PHA), in which case PLA, novel blends of PLA with PHAs,
or blends of PLA with PBAT and PBS, or blends of PLA and PHAs with PBAT and
PBS or other biodegradable polymers is made therefrom. These novel fabrics and
19
laminates have enhanced biodegradation in environments containing
microorganisms while possessing good shelf-life and good strength, flexibility and
pliability. The fabric substrate to be laminated may be woven, knitted or
non-woven fabric. The biodegradable films may be produced by blown film
process, cast film process, thermoforming, vacuum forming or extrusion coating5 .
In the extrusion coating of the film onto the fabric, an adhesive which is needed in
most of other processes is not usually required. However, it is necessary to adhere
the film to the fabric with an adhesive or hot melt which may also be
biodegradable.
10 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Although the biodegradation of P(3HB-co-4HB) product is easy to occur in
soil, sludge and sea water, the biodegradation rate in water in the absence of
microorganisms is still very slow (Saito, Yuji, Shigeo Nakamura, Masaya
Hiramitsu and Yoshiharu Doi, “Microbial Synthesis and Properties of
15 Poly(3-hydroxybutyrate-co-4-hydroxybutyrate),” Polymer International 39 (1996),
169-174). Thus, the shelf life of P(3HB-co-4HB) product in clean environment
such as dry storage in sealed package or in clean wipes cleansing solution etc. is
very good. However, when located in dirty environments containing
microorganisms such as soil, river water, river mud, compost of manure and sand,
20 sludge and sea water, the disposed P(3HB-co-4HB) fabric, P(28.56- cooperative
hydroxybutyrate) fabric, film and packaging material are easy to degrade. It should
be pointed out that polylactic acid (PLA) is easy to be composed instead of being
degraded in the dirty environments above. Heat and moisture in the resulting
compost pile must firstly break the PLA polymer into smaller polymer chains
25 which finally degrade to lactic acid. After that, microorganisms in the compost and
soil consume the smaller polymer fragments and lactic acid as the nutrients.
20
Accordingly, the mixing of hydroxybutyrate with PLA may accelerate the
degradation rate of blend product made from PHAs-PLA such as P(3HB-co-4HB).
Furthermore, product made by mixing PHAs with PLA has extended its shelf life
in clean environment. Although the price of PLA has decreased substantially over
the past 10 years to just a little more than that of synthetic polymers such a5 s
polypropylene and PET polyester, the price of PHAs still remains two to three
times higher than that of PLA. This is because PLA is synthesized on a large scale
from lactic acid, while PHAs are produced by bacteria with specific carbon source
and have to be extracted from the bacteria with a solvent. Therefore, it is not
10 commercially feasible to mix more than 25% PHA with PLA to melt extrude
products such as woven and knitted fiber, nonwoven fabric, film, food packaging
container, etc.
Four groups of sample solution formulations are listed in tables 1-4, which are
formulations for 400 Kg of clean wipes cleaning solution (typically the liquid
15 contained in package of baby wipes); river water collected from the East River in
Dongguan of China with some river mud; river mud collected from the East River
in Dongguan of China; and a mixed compost of silt, sand and cow manure,
respectively. The above-mentioned starting materials are mixed with distilled water
and the resulting mixture is adjusted to a pH value of above 7 with dilute KOH.
20 Two sample solutions with identical formulation are used for each treatment. Each
of the treatment boxes containing the samples exposed to the treatment is covered
and the pH value and percentage of solid are determined every two weeks. Average
results in the first 4 weeks of exposure are shown in Table 5.
In one embodiment of this invention, two blends of PLA and PHB, i.e. 25 Kg
25 of blend of 85% PLA (NatureWorks 2002D) and 15% PHB (3HB-co-4HB) as well
as 25 Kg of blend of 75% PLA (NatureWorks 2002D) and 25% PHB
(3HB-co-4HB) are melt blended and extruded as pellets that are then shipped to
21
Biax-Fiberflilm Corporation, Greenville, WI, USA. Those pellets are melt spun to
produce meltblown (MB) fabric with a basis weight of 50 g/m2. For the purpose of
comparative test, MB fabric of 100% PLA (NatureWorks 2002D) is also produced.
During the MB process of these polymers, it becomes increasingly obvious that
melting and hot air temperature used to prepare the MB fabric are too high sinc5 e
the 2002D PLA polymer has a very low melt index (indicating a very high
molecular weight of PLA) and it requires higher temperature to increase the
fluidity of MN PLA for its smooth extrusion through the meltblown die orifice.
The melting temperature of 100% 2002D PLA is 274 °C and the hot air
10 temperature is 576°C. On contrary, a melting temperature of 266 °C and a hot air
temperature of 260 °C are generally applied for melt spinning spunbond grade PLA
with a melt index of 70-80 (Wadsworth, Larry and Doug Brown, “High Strength,
High Quality Meltblown Insulation, Filters and Wipes with Less Energy,”
Presentation to Guangdong Nonwovens Association Conference, Dongguan, China,
15 November 26-27, 2009). Therefore, owing to such two blends, the PHB component
contained apparently undergoes some thermal degradation, which is evidenced by
much smoke coming from the extruded MB fiber and the low strength of the
produced MB PLA/PHB fabric. In the following experiments, it is scheduled that
PLA polymer (NatureWorks PLA 6251 D) with higher melt index (which is
20 70-85 and requires for much lower MB processing temperature) is employed to be
mixed with PHB in the same ratio. In addition, similar composition using the
6251D PLA is scheduled to be made on a 1-meter spunbond non-woven pilot line.
This typically operates at a temperature that is only a little above the melting point
of the PLA and the blended PLA-PHB polymer so that even less thermal
25 degradation occurs. This is because a filament drafting step absent from the MB
process is adopted in the SB process, and thus the produced filament is obviously
larger than that produced from the same polymer. Compared to the MB fabric with
22
a diameter of 2-8 μm, the average diameter of the fiber in SB fabric is typically
12-25 μm. The second MB operation and SB operation of these polymer
compositions will reduce the thermal degradation effect to a maximum extent, and
thus the degradation observed in the biodegradation process is mainly from
biodegradation. Also, since the MB and SB non-woven fabrics have larg5 e
differences in their diameters, the smaller MB fiber has more surface area and is
expected to undergo biodegradation more readily and more quickly.
The MB 100% 2002D MB fabric, the 85% 2002D PLA/15% PHB and the
75% 2002D/25% PLA rolled to have a width of 12.5 inch and a density of 50 g/m2
10 are shipped from Biax-Fiberfilm Company back to U.S. Pacific Nonwovens &
Technical Textile Technology (DongGuan) Limited which is located at No.2 East
Dyke, Aozhitang Industrial Park in Dongcheng District, Dongguan of Guangzhou
Province of China and subordinate to U.S. Pacific Nonwovens Industry. Herein,
1.5 meter of each fabric is immersed with different treatment methods and then left
15 exposed to different treatment fluids together with samples to be removed from
each treatment box, while the corresponding repeated treatments are carried out at
intervals of 4 weeks, 8 weeks, 12 weeks, 16 weeks and 20 weeks.
Below is the specific experiment process. First of all, MB PLA and PLA-PHB
fabrics added with clean wipes cleaning solution are stored in a porous steel basket
20 and further exposed in the treatment box. After four weeks’ treatment, MB sample
in compost is gently washed in a nylon stocking. Thereafter, corresponding
degradation conditions can be observed after washing and drying. Some river
water is applied to the MB fabric in the same manner as that of the clean wipes
cleaning solution. Then the MB fabric is placed in the porous steel basket in the
25 covered treatment box until samples of the 100% MB PLA, 85% PLA-15% PHB,
and 75% PLA-25% PHB are removed from all of the treatment boxes at an interval
of 4 week increments up to a total of 20 weeks. In the case of river mud and
23
silt/sand/manure compost, the fabric to be exposed thereto is first laid onto the
treatment box while being immersed and thoroughly penetrated by the treatment
solution. Subsequently, the fabric is inserted into a nylon panty hose stocking with
one half of a 1.5-meter sample being placed into one leg and the other half into the
other leg. The stocking containing the fabric is then gently pulled over the sampl5 e
and buried into the proper box containing some river mud or compost. Besides, the
treatment box is attached with a label by a nylon string for each stocking. The
fabric samples removed every 4 week are laid onto a metal box with a wire screen
on the bottom. In this case, a nylon knitted fabric is placed on top of the wire mesh,
10 and the treated fabric is gently washed by applying some low pressure water onto
the palm. Then a second nylon knitted fabric is placed on top of the washed sample
and the fabric is gently turned over to wash the other side. Finally, all of the
washed and treated fabrics are placed on a laundry drying table and dried over two
days until dry before being taken to the laboratory for test. A portion of each of the
15 treated and dried fabrics is sent to an external laboratory for scanning electron
microscopy analyses to determine the extent of fiber breakage as an experimental
result of the treatment process. In addition, gel permeation chromatography is
adopted to determine if some changes and presumable loss in molecular weight of
the polymer occur during exposure to the different treatments, and differential
20 thermal analysis is adopted to determine any changes in crystalline phase. After
four weeks’ different treatments, test results for physical property of the fabrics are
shown in tables. Herein, table 6A is specific to 100% 2002D PLA MB fabric, table
7A to 85% 2002D PLA /15% PHB MB sample, and table 8A to 75% 2002D/25%
PHB fabrics. The 100% MB PLA sample loses 6% of the machine direction (MD)
25 tensile strength after exposure in the clean wipes cleaning solution for 4 weeks,
while the 85%PLA/15% PHB and 75%PLA/PHB fabrics only lose 4% and 1% of
the machine direction (MD) tensile strength, respectively, in the clean wipes
24
cleaning solution. However, all of the 100% PLA, 85% PLA/15% PHB and 75%
PLA/25% PHB lose 50%, 32% and 65% of cross machine direction (CD) trapezoid
tearing strength, respectively. After 4 weeks in the river water, 100% MB PLA
loses 26% of MD tensile strength and 64% of CD tearing strength, and the 85%
PLA/15% PHB and 75% PLA/25% PHB lose 19% and 22% of MD tensile strengt5 h
and 77% and 80% of CD tearing strength, respectively. After 4 weeks in the river
mud, the 100% PLA fabric loses 91% of MD tensile strength and 98% of CD
tearing strength, and the 85% PLA/15% and 75% PLA/25% PHB lose 76% and
75% of MD tensile strength and 96% and 87% of CD tearing strength, respectively.
10 After 4 weeks in the silt/sand/cow compost, the 100% PLA loses 94% of MD
tensile strength and 99% of CD tearing strength, and the 85% PLA/15% PHB and
75% PLA/25% PHB lose 76% and 86% of MD tensile strength and 99% and 83%
of CD tearing strength, respectively. The air permeability of all the samples
exposed to the river mud and compost increases, which causes higher air
15 permeability value and indicate more open structures with the increase of
biodegradation. Less increase in air permeability is caused to the MB 100% PLA
fabric when compared with the PLA-PHB blend fabric under different treatments.
Besides, none of the fabrics loses any weight and in fact some gain weight since it
is difficult to remove all of the treatment debris from the samples without causing
20 further damage to the fabrics.
The exposure effects in different treatments for 12 weeks of the 100% 2002D
PLA MB fabric, 85% PLA/15% PHB, and 75% PLA/25% PHB are shown in
Tables 6B, 7B, and 8B, respectively. After these fabrics have been stored on a roll
wrapped in plastic for 16 weeks, the 85% PLA/15% PHB are not notably low in
25 MB and CD tenacity after 16 weeks storage, while the 75% PLA/25% PHB shows
22% loss in MD tenacity and 33% loss in CD tenacity. As what is found after 4
weeks of exposure to different treatments, after 12 weeks of exposure, MD and CD
25
tenacities compared to those of the corresponding domestic fabrics are higher in
the clean wipes solution with 100% PLA as compared to two blends of PLA and
PHB. All of the samples show appreciable degradation in river water, river mud
and silt/sand/manure compost after 12 weeks.
5
Table 1 Formulation for Clean Wipes Cleaning Solution Loaded in Two Different Boxes
Ingredient Weight Percentage (%) Weight (Kg)
Purified Water 97.56 390.24
Propylene Glycol 1.2 4.8
Lanolin 0.6 2.4
Cocoamphodiacte 0.3 1.2
Polysorbate-20 0.1 0.4
Ethylparaben 0.0167 0.0668
Methylparaben 0.0167 0.0668
Propylparaben 0.0167 0.0668
Benzalkonium Chloride 0.075 0.3
Disodium EDTA 0.075 0.3
Citric Acid 0.01 0.04
aromatic hydrocarbon 0.03 0.120
Total 100.0 400 Kg (approx. 400 L)
Table 2 Composition of River Water in Each of Two Boxes
Ingredient Weight (Kg)
River Water 380
River Mud 20
Total 400 Kg
10 Table 3 Composition of River Mud in Each of Two Boxes
Ingredient Weight (Kg)
River Mud 300
River Water 100
Total 400
Table 4 Weight Compositions of Silt, Sand, Cow Manure and Distilled Water in Each of the
Two Boxes
Ingredients Weight percentage (%) Weight (Kg)
26
Silt 23 69
Sand 23 69
Cow Manure 23 69
Distilled Water 31 93
pH value is adjusted to 7.5 by 10%
Potassium Hydroxide.
(Weight of KOH is included in the
composition of distilled water.)
Total 100 300 Kg
Illustration of table 4:
69Kg of dry silt (obtained from river by USP gardener) is added to a large
mixing container;
69Kg of dry cow manure is added, which has already been broken up into
small pieces by a large electric mixer5 ;
69Kg of dry sand is added slowly during mixing operation;
83Kg of distilled water is added slowly during stirring operation;
In the case of complete mixing, pH value is detected by a litmus paper or a pH
meter. 10% potassium hydroxide (prepared in distilled water) is added slowly until
10 the pH value reaches 7.5.
Remaining amount of distilled water is added so that the water containing
calcium hydroxide accounts for 93Kg in total. pH value is checked and further
adjusted to 7.5.
15 Table 5 pH Value and Percentage of Solids in Treatment Boxes for Biax MB PLA (2002D) and
MB PLA (2002D) Blended with 15% and 25% PHB
Treatment p H v a l u e Percentage
of solid
First Replication Average First Replication Average
Clean wipes Cleaning Solution 3.92 3.94 3.93 1.30 1.32 1.31
River Water 6.89 6.98 6.94 0.13 0.14 0.14
River Mud 7.19 7.18 7.18 51.8 50.4 51.1
Silt/Sand/Manure Compost
7.36 7.51 7.44 52.4 54.6 53.5
27
Table 6A Weight, Thickness, Air Permeability and Strength Properties of 100% PLA (2002D) at
post-production and after Exposure for Four Weeks to Clean Wipes Cleaning Solution, River
Water, River Mud and Silt/Sand/Manure Compost
100% PLA
2002D after
4 Weeks
Weigh
t
(g/m2)
Thickness
(mm)
Air
Perm.
(l/m2.s)
Tenacity
(N)
Elongation
(%)
Tearing
Strength
(N)
MD CD MD CD CD
%
Loss
%
Los
s
Post-produc
tion
46.4 0.400 2122 31.8 14.0 10.1 57.2 22.1
Clean wipes
Cleaning
Solution
47.2 0.366 2298 29.9 6 12.8 6.8 29.8 11.0 50
River
Water
45.8 0.384 2260 23.6 26 9.8 3.2 3.8 8.0 64
River Mud 49.2 0.394 2672 3.0 91 1.2 3.0 1.2 0.4 98
Silt/Sand/
Manure
Compost
56.8 0.472 2506 1.8 94 0.6 0.7 0.4 0.2 99
5
Table 7A Weight, Thickness, Air Permeability and Strength Properties of 85% PLA
(2002D)/15% PHB at post-production and after Exposure for Four Weeks in Clean Wipes
Cleaning Solution, River Water, River Mud and Silt/Sand/Manure Compost
85%
PLA/15%
PHB after 4
Weeks
Weigh
t
(g/m2)
Thickness
(mm)
Air
Perm
(l/m2.s)
Tenacity
(N)
Elongation
(%)
Tearing
Strength
(N)
MD CD MD CD CD
%
Loss
%
Los
s
Post-produc
tion
57.8 0.455 3134 14.4 9.7 19.8 32.9 7.9
Clean wipes
Cleaning
Solution
52.5 0.536 3876 13.8 4 9.4 13.5 21.3 3.4 57
River
Water
58.8 0.460 3024 11.6 19 7.2 4.2 7.0 1.8 77
River Mud 63.2 0.531 3639 3.4 76 2.2 2.7 3.4 0.3 96
Silt/Sand/
Manure
59.8 0.508 3916 3.5 76 1.4 3.6 3.6 0.1 99
28
Compost
Table 8A Weight, Thickness, Air Permeability and Strength Properties of 75% PLA
(2002D)/25% PHB at Post-production and after Exposure for Four Weeks in Clean Wipes
Cleaning Solution, River Water, River Mud and Silt/Sand/Manure Compost
75%
PLA/25%
PHB after 4
Weeks
Weigh
t
(g/m2)
Thickness
(mm)
Air
Perm
(l/m2.s)
Tenacity
(N)
Elongation
(%)
Tearing
Strength
(N)
MD CD MD CD CD
%
Los
s
%
Loss
Post-produc
tion
53.8 0.387 3740 8.5 3.6 5.2 12.0 3.7
Clean wipes
Cleaning
Solution
56.2 0.344 3708 8.4 1 3.8 2.5 4.4 1.3 65
River
Water
53.6 0.338 3627 6.6 22 2.4 1.6 1.8 0.74 80
River Mud 53.7 0.403 4502 2.1 75 0.8 2.6 2.6 0.48 87
Silt/Sand/
Manure
Compost
61.5 0.460 5448 1.2 86 0.8 3.6 9.1 0.62 83
5
Table 6B Weight, Thickness, Air Permeability and Strength Properties of 100% PLA (2002D)
MB Wet Wipes at Post-production After 3 and 16 Weeks and After Exposure for 12 Weeks in
Clean Wipes Solution, River Water, River Mud and Silt/Sand/Manure Compost
100% PLA
2002D After
12 Weeks
Weight
(g/m2)
Thickness
(mm)
Air
Perm
(l/m2.s)
Tenacity
(N)
Elongation
(%)
Tearing
Strength
(N)
MD CD MD CD CD
%
Loss
%
Loss
%
Loss
Post-produc
tion after 3
Weeks
46.4 0.400 2122 31.8 14.0 10.1 57.2 22.1
Post-produc
tion after 16
Weeks
44.8 0.396 2079 32.2 0 12.7 9 7.0 45.4 9.8 56
Clean Wipes
Solution
46.7 0.41 2328 14.5 54 3.8 73 1.2 1.0 2.3 90
29
River Water 46.6 0.392 2272 4.9 85 2.4 83 0.6 0.7 0.8 96
River Mud 49.2 0.408 2652 0.6 98 0.2 99 0.9 0.2 0.3 99
Silt/Sand/
Manure
Compost
* * * * * * * * * * *
*Samples are too disintegrated to perform physical testing.
Table 7B Weight, Thickness, Air Permeability and Strength Properties of 85% PLA
(2002D)/15% PHB at Post-production After 3 and 16 Weeks and After Exposure for 12 Weeks
in Clean Wipes Solution, River Water, River Mud and Silt/Sand/Manure Compos5 t
85%
PLA/15%
PHB After
12 Weeks
Weight
(g/m2)
Thickness
(mm)
Air
Perm
(l/m2.s)
Tenacity
(N)
Elongation
(%)
Tearing
Strength
(N)
MD CD MD CD CD
%
Loss
%
Loss
%
Loss
Post-produc
tion after 3
Weeks
57.8 0.455 3134 14.4 9.7 19.8 32.9 7.9
Post-produc
tion for 16
weeks
54.9 0.441 3049 15.0 0 9.5 2 19.2 31.5 7.1 10
Clean Wipes
Solution
60.6 0.576 3418 10.0 31 5.4 44 4.2 8.0 2.3 71
River Water 61.4 0.506 2853 8.5 41 6.3 35 5.6 11.4 2.2 72
River Mud 66.9 0.522 3020 2.5 83 1.9 80 2.1 2.7 0.6 92
Silt/Sand/
Manure
Compost
62.6 0.490 3152 2.5 83 3.2 67 2.4 4.8 1.1 86
*Samples are too disintegrated to perform physical testing.
Table 8B Weight, Thickness, Air Permeability and Strength Properties of 75% PLA
(2002D)/25% PHB at Post-production d After 3 and 16 Weeks and After Exposure for 12 Weeks
10 in Clean Wipes Solution, River Water, River Mud and Silt/Sand/Manure Compost
75%
PLA/25%
PHB After
12 Weeks
Weight
(g/m2)
Thickness
(mm)
Air
Perm
(l/m2.s)
Tenacity
(N)
Elongation
(%)
Tearing
Strength
(N)
MD CD MD CD CD
%
Loss
%
Loss
%
Loss
30
Post-produc
tion after 3
Weeks
53.8 0.387 3740 8.5 3.6 5.2 12.0 3.7
Post-produc
tion after 16
Weeks
55.5 0.383 3339 6.6 22 2.4 33 1.5 1.6 1.5 59
Clean Wipes
Solution
56.8 0.376 3838 4.6 46 1.9 47 1.4 2.2 0.7 81
River Water 46.8 0.346 3182 4.4 48 1.4 61 0.9 0.6 0.5 86
River Mud 57.4 0.440 5129 1.1 87 1.1 69 2.0 2.9 0.7 81
Silt/Sand/
Manure
Compost
* * * * * * * * * * *
*Samples are too disintegrated to perform physical testing.
In addition to the biodegradation studies described above, pure PBAT films in
a thickness of 9 micron (μm) with or without 20% calcium carbonate are obtained
from a vendor in China. Meltblown (MB) Vistamaxx® containing 20% PP is
obtained from Biax-Fiberfilm Corporation in Neenah, WI, USA. Spunbond (SB5 )
PLA pigmented black with carbon black with a nominal weight of 80 g/m2 is
obtained from Saxon Textile Research Institute in Germany. The pure PBAT film
and PBAT film with 20% calcium carbonate are laminated in separate trials to
Vistamaxx MB containing 20% PP and black SB PLA using hot-melt adhesive of
5-13 g/m2. At this point, hot-melt adhesive generally of 0.5-12 g/m2 10 and preferably
of 1-7 g/m2 are adopted. In addition, two layers of SB PLA are laminated and
adhered using hot-melt adhesive. All of the raw materials and laminates are tested
as shown in Table 9 for weight, thickness, tenacity, elongation-to-break, tearing
strength, bursting strength, water vapor transmission rate (WVT) and hydrohead. It
15 should be pointed that these are only some samples of different embodiments of
this invention and that in addition to using a hot-melt technology to adhere
different layers of the materials below together, the PBAT films or other
biodegradable/compostable films can be directly applied to the substrates by
extrusion coating without the necessary adoption of an adhesive. The laminate can
20 be joined or bonded together by a portion of technologies listed below such as
31
thermal point calendaring, overall-calendering or ultra-sonic welding. Furthermore,
instead of a hot-melt adhesive, glue, or water or solvent-based adhesives or latexes
can be used to adhere the laminates together.
As shown in Table 9, the 9 μm pure (100%) PBAT film (sample 1) has good
elongation in the MD direction and very high elongation of over 300% in the CD5 .
The bursting strength test cannot be performed on samples 1 through 5 because all
of these samples are so elastic that the films and laminates do not rupture during
the test and appeared free of deformation after the test. The water vapor
transmission rate of sample 1 is rather high at 3380g/m2/24 hours as was the
10 hydrostatic head at 549 mm. The PBAT film containing 20% calcium carbonate
(CaCO3) (sample 2) has similar properties as sample 1 with the same WVTR and
lower hydrohead. PBAT film similar to samples 1 and 2 with a smaller thickness of
6 μm or less would also be expected to have good elongation and higher WVTR,
although its hydrohead may be lower. The meltblown (MB) sample 3, containing
15 80% Vistamaxx® (Vistamaxx polyolefin-based polymer high in elasticity and
produced by ExxonMobil) and 20% PP has a very high MD and CD elongation of
about 300% and a very high WVTR of 8816 g/m2/24 hours when the fabric is
fairly open. However, the hydrohead of sample 3 is rather high at 1043 mm, which
indicates it still has good barrier properties. It should be pointed that 20% PP is
20 added to the Vistamaxx polymer pellets and physically mixed before the blend is
fed into an MB extruder and melted so that the Vistamaxx MB fabric will not be
too sticky. If 100% Vistamaxx is meltblown, it will be very sticky, block on the roll
and be difficult to un-wind for lamination or use later. Nevertheless, it is most
feasible to meltblow 100% Vistamaxx if the MB Vistamaxx is laminated in-line
25 with a film such as PBAT or PBS with or without CaC03 or to another non-woven,
scrim or fabric. In fact it may not be necessary to use an adhesive since 100%
Vistamaxx or a higher concentration of Vistamaxx is already very sticky.
32
Compared to the unique adoption of Vistamaxx, the lamination of the pure
PBAT and PBAT containing 20% CaC03 with Vistamaxx using a hot-melt adhesive
notably increases the MD and CD tenacity. These samples also have very high MB
elongation and particularly high CD elongation (390% for sample 4 and 542% for
sample 5). Also, samples 4 and 5 have notably high MVTR values of 1671 an5 d
1189 g/m2/24 hours and high hydroheads of 339 and 926 mm H2O, respectively.
Again it should be pointed that the PBAT films can be extrusion-coated directly
onto MB 100% Vistamaxx or onto MB Vistamaxx with some PP with or without
the use of a hot-melt adhesive, and the extrusion-coating process can allow a much
10 thinner PBAT film to be used, possibly as low as 4 or 5 μm, with a resulting higher
MVTR but with possibly lower hydrohead.
The black SB PLA with a target weight of 80 g/m2 has a MD tenacity of 104
N and a CD tenacity of 31 N, while its MD elongation is low to be 3.6% and CD
elongation is high to be 30.7%. Its busting strength is 177 KN/m2, the WVTR is
rather high at 8322 g/m215 /24 hours and the hydrohead is notable at 109 mm. The
MD and CD tenacity of the 80 g/m black SB PLA, which is laminated to pure
PBAT with hot-melt adhesive, are higher than those with the SB PLA alone at 107
and 39 N, respectively, but its CD elongation is only 9.8%. However, the PBAT
laminated SB PLA has higher bursting strength at 220 KN/m2. The breathability is
still good with a WVTR of 2459 g/m220 /24 hours and a very high hydrohead of 3115
mm H2O. The SB PLA laminated with PBAT containing 20% CaCO3 has similar
properties to sample 8, except that the hydrohead still high at 2600 mm H2O
becomes lower. The lamination of SB PLA with thinner PBAT film, and especially
with thinner PBAT film deposited by extrusion coating, produces protective
25 apparel for medical, industrial or sports applications. At this regard, the lamination
has high MVTR for wearing comfort and high hydrostatic head for barrier
protection. The barrier protection can be further enhanced by the application of a
33
repellent finish (fluorochemical silicone or other types of repellent finishes) to
either the PBAT film side or to the SB PLA on either side before or after
lamination with the film. Another enhancement is the lamination of MB PLA with
SB PLA before or after lamination with the film. The repellent finishing agent can
also possibly be added to the polymer melt used to produce the PBAT film, SB o5 r
MB PLA, for example.
When two layers of SB PLA are melt-adhesively bonded together to produce
sample 9, the MD and CD tenacities and bursting strengths are essentially twice as
those of one layer of sample 6. The target MD and CD tenacities and
10 corresponding elongation-to-break (% elongation) values of patient lifting slings
produced from 110 g/m2 SB PP are at least 200 and 140 N/5cm, respectively. As
shown in Table 9, the MD tenacity of the two adhered layers of SB PLA is 215 N
but their CD tenacity is only about 50% of the required level. Also the MD and
CD % elongation values are much lower than the required minimum of 40%. The
15 MD and CD elongations of SB PLA can be improved by blending PBAT from 5 to
60% (preferably from 20 to 50% PBAT) with the PLA prior to extrusion of the SB
fabrics. Furthermore, PBAT and PBS may be blended with PLA to achieve fabric
with the desired MD and CD tenacity and elongation values as well as stability to
heat exposure. Furthermore, the SB filament web may be bonded by processes
20 other than thermal point calendaring to achieve greater multi-directional strength
and elongation to include hydroentanglement and needlepunching. Needlepunched
SB PLA can be produced at greater weights than 110 g/m2 without the need to
laminate and bond two or more SB PLA fabrics together to achieve the required
strength and elongation values.
25
Table 9 Strength and Barrier Properties of Laminates of PBAT Film with Meltblown (MB)
Vistamaxx® and Spunbond (SB) PLA and of a Laminate of Two SB PLA Layers
Sample No./
Description
Weigh
t g/m2
Thick
mm
Tenacity
N/5 cm
Elongation
%
Tear
Strength
Burst
Strength
WVTR
g/m224
Hydroh
ead
34
Trapzoid, N KN/m2 hr mm H2O
MD CD MD CD MD CD
1/Pure PBAT
Film, 9 μm
8.9 0.009 10.0 5.1 67.7 307.
6
1.5 14.6 *DNB 3380 549
2/PBAT Film
with 20%
CaCO3
9.3 0.010 8.9 4.1 48.1 296.
3
1.8 8.0 DNB 2803 415
3/MB
Vistamaxx &
20% PP
42.1 0.229 17.2 11.6 304.0 295.
8
16.0 8.6 DNB 8816 1043
4/PBAT Film
+ Vistamaxx
63.9 0.242 31.4 16.0 179.5 390.
0
24.6 8.5 DNB 1671 339
5/PBAT Film
+ 20% CaCO3
+ Vistamaxx
65.3 0.249 25 17.7 116.6 541.
9
22.0 10 DNB 1189 926
6/Black 80
gsm SB PLA
81.3 0.580 102.4 30.7 3.6 30.7 6.2 12.0 177 8322 109
7/Black 80
gsm SB PLA +
Pure PBAT
Film
101.3 0.584 107.0 39.2 4.6 9.8 8.5 20.7 220 2459 3115
8/Black 80
gsm SB PLA +
PBAT
Film-20%
CaCO3
96.5 0.557 97.0 36.3 4.9 8.0 9.3 19.0 151 2353 2600
9/2 Layers of
Black SB PLA
Bonded by 3
gsm
hot-Melt
183.6 1.060 215.3 76.8 4.9 9.4 14.7 22.5 503 7886 70
*DNB – free of burst due to high elasticity

We claim:
1. A biodegradable film comprising PHAs and PLA, wherein the content of PLA
is 1%-95% in mass percent.
2. The biodegradable film according to claim 1, wherein the content of PLA is
10%-50% in mass percent5 .
3. The biodegradable film according to claim 1, wherein the PHAs are PHBs or
PHVs, or a copolymer or blend of PHBs and PHVs.
4. The biodegradable film according to claim 3, wherein the PHBs are
P(3HB-co-4HB) polymerized by 3HB and 4HB.
10 5. The biodegradable film according to claim 3, wherein the mole percent of
4HB ranges from 5% to 85%.
6. The biodegradable film according to claim 1, wherein further comprising
cellulose fiber.
7. The biodegradable film according to claim 1, wherein the biodegradable film
15 is configured for producing film, container for solid and liquid, rigid or
flexible package, woven, knitted and non-woven fabric with filament and
staple fiber, and composite product of fabric and film through thermal forming,
injection molding or melt spinning.
8. The biodegradable film according to claim 7, wherein the melt spinning
20 comprise spunbond and meltblown processes.
9. The biodegradable film according to claim 7, wherein the non-woven fabrics
are bonded by wet adhesive or dry adhesive.
36
10. The biodegradable film according to claim 7, wherein non-woven fabrics are
obtained by needlepunching, hydroentangling, thermal calendaring, hot air
through-air thermal bonding or the following heating processes including
microwave, ultrasonic wave, welding, far infrared heating and near infrared
heating5 .
11. The biodegradable film according to claim 7, wherein the composite product is
laminated film or fabric which combines with spinning laying,
needlepunching, air laying of pulp or fiber, or hydroentangling processes.
12. The biodegradable material according to claim 11, wherein the laminate
10 comprises non-woven process of thermal spunbond-meltblown-spunbond type
or ultrasonically bonded type, wherein the composite product is used for
industrial protective clothing and medical protective clothing.
13. The biodegradable material according to claim 11, wherein the composite
product includes meltblown filter media which exists as outer and inner
15 facings through spun bonding and is sewn or thermally or ultrasonically
bonded on the edges.
14. Biodegradable laminate, wherein comprising PBAT and biodegradable film as
recited in any one of claims 1-13.
15. The biodegradable laminate according to claim 14, wherein the content of
20 PBAT is 5%-60% in mass percent in the biodegradable laminate.
16. The biodegradable laminate according to claim 14, wherein further comprising
filler in a mass percent of 5-60%.
37
17. Biodegradable laminate, wherein comprising PBS and biodegradable film as
recited in any one of claims 1-13.
18. The biodegradable laminate according to claim 17, wherein the content of PBS
is 5%-40% in mass percent in the biodegradable laminate.
19. Biodegradable laminate, wherein comprising blend of PBS and PBAT as wel5 l
as biodegradable film as recited in any one of claims 1-13.
20. The biodegradable laminate according to claim 19, wherein the contents of
PBS and PBAT are 5%-40% and 5-50% in mass percent in the biodegradable
laminate, respectively.