JP2005162884A - Film using poly(3-hydroxyalkanoate) composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a film using a PHA(polyhydroxyalkanoate) composition usable in various film applications through obtaining gas-barrier tendency such as for oxygen/water vapor and flexibility and also excellent in biodegradability as one of disposal means, namely, good in such environmental adaptability as to be easy to undergo disposal treatment after used, and to provide a method for producing the film. <P>SOLUTION: The film is prepared from (A) an aliphatic polyester( hereafter, referred to as poly(3-hydroxyalkanoate), abbreviated as P3HA ) composed of recurring units of the formula(1):[-CHR-CH<SB>2</SB>-CO-O-]( R is an alkyl group represented by C<SB>n</SB>H<SB>2n+1</SB>; and (n) is an integer of 1-15 ). In this film, the P3HA comprises (a) a P3HA having a weight-average molecular weight Mw<SB>a</SB>(1×10<SP>4</SP>≤Mw<SB>a</SB>≤3×10<SP>6</SP>) and a melting temperature Tm<SB>a</SB>and (b) another P3HA having a weight-average molecular weight Mw<SB>b</SB>(1×10<SP>4</SP>≤Mw<SB>b</SB>≤1×10<SP>7</SP>) and a melting temperature Tm<SB>b</SB>( wherein, Tm<SB>b</SB>≥Tm<SB>a</SB>+5°C ). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a biodegradable resin film using a poly (3-hydroxyalkanoate) composition.

  Conventionally, plastics have been disposable due to ease of processing and use, difficulty in reuse, and hygiene problems. However, as plastics are used and disposed of in large quantities, the problems associated with landfilling and incineration are becoming more important. Ecosystems due to the shortage of landfills and non-degradable plastics remaining in the environment Impact on the environment, generation of harmful gases during combustion, global warming due to large amounts of combustion heat, etc. In recent years, biodegradable plastics have been actively developed as a solution to the problem of plastic waste. In general, biodegradable plastics are: 1) microbially produced aliphatic polyesters such as polyhydroxyalkanoates (hereinafter referred to as PHA), 2) chemically synthesized aliphatic polyesters such as polylactic acid and polycaprolactone, 3) starch, It is roughly classified into three types, such as natural polymer such as cellulose acetate. Among chemically synthesized aliphatic polyesters, polylactic acid and polycaprolactone have problems in heat resistance, and natural polymer substances have problems such as non-thermoplasticity and poor water resistance.

  On the other hand, PHA is excellent in degradability under aerobic and anaerobic conditions, does not generate toxic gas during combustion, and can be made high molecular weight with plastic derived from microorganisms using plant raw materials. It has excellent characteristics such as carbon neutrality. In particular, the properties that decompose under anaerobic conditions and the fact that high molecular weight is possible are notable performances. The PHA is classified as an aliphatic polyester, but is different from the above-described chemically synthesized aliphatic polyester in that the polymer properties are significantly different.

  In this way, PHA consists of natural ingredients, solves the problem of waste, and is excellent in environmental compatibility, so it can be applied to packaging materials, tableware materials, construction / civil engineering / agriculture / horticultural materials, adsorption / carrier / filter materials A possible shaped body is desired.

  However, PHA has difficulties in molding processability such as a low crystallization speed, and has not yet reached the required physical properties for various uses, so that it has not been widely used to manufacture molded products. It is.

  On the other hand, gas barrier properties, strength, and the like are required as important physical properties for packaging materials used for packaging foods, medicines, industrial products, agriculture, waste waste, and the like. The gas barrier property is required to have low permeability to oxygen and low permeability to water vapor, particularly in food packaging applications. In terms of strength, it is often desirable to provide a product with flexibility. Conventionally, biaxially stretched polyester films, biaxially stretched nylon films, and the like have been widely used for such packaging materials. These general-purpose plastics are excellent in strength and durability and are widely used due to their low cost. However, when they are thrown into the environment after use, they are decomposed due to their durability. It has a disadvantage from the viewpoint of environmental suitability that remains in the environment.

  In order to solve these problems, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (hereinafter referred to as PHBV) which is a PHA is used as a main component, and a diluent system such as a plasticizer is used. A film having biodegradability and gas barrier properties is disclosed (see Patent Document 1). However, PHBV itself has a high crystallinity and is brittle, and in order to obtain flexibility, in the example of Patent Document 1, 60 parts by weight of a plasticizer is added to 100 parts by weight of the resin. As a result, the heat resistance of the resin is lowered, the plasticizer bleeds out, and it tends to stick, which is not preferable.

  Further, as an example of improving the brittleness of the resin, by stretching poly (3-hydroxybutyrate) (hereinafter referred to as PHB) which is a PHA at 155 to 180 ° C., the tensile strength is 30 MPa or more, and It is disclosed regarding a stretched oriented film having a breaking elongation of 15% or more (see Patent Document 2). However, although it has a gas barrier property, PHB itself is also very brittle, so improvement can be seen in the invention, but it has not yet reached the level of application for film applications that require flexibility. .

  Moreover, it is disclosed regarding the food provision article containing the film which consists of a PHA random copolymer (refer patent document 3). The invention is to provide an article including a film having good oil and fat resistance, water resistance, and strength characteristics. However, it is a feature of the invention that flexibility and molding processing are easy, and a film such as gas barrier property is provided. It has not led to an invention of its own functionality.

  Further, there is disclosed a resin laminate having both a biodegradability and an oxygen permeability, which is composed of a resin layer mainly composed of polylactic acid which is PHA / a resin layer containing an oxygen-absorbing metal (see Patent Document 4). ). In the present invention, by laminating an oxygen-absorbing resin layer, an effect is seen in terms of permeability to oxygen, but polylactic acid itself is poor in hydrolysis resistance against water vapor, and thus satisfies both. However, since polylactic acid itself is a hard and brittle material, there are still problems in terms of flexibility.

In this way, when PHB and PHBV, which are PHAs, are taken as an example, the resin itself has a gas barrier property because of its high crystallinity, but conversely, since the resin itself is brittle, the gas barrier property and flexibility A biodegradable PHA film having the properties has not been seen yet.
Japanese Patent Publication No. 6-74340 Japanese Patent Laid-Open No. 10-176070 Special table 2003-518998 gazette Japanese Patent Laid-Open No. 2002-200725

  The object of the present invention is to obtain a biodegradable resin film having both gas barrier properties such as oxygen and water vapor and flexibility, and PHA is used as a base resin for that purpose. For example, in food applications, food bags (food storage bags, sandwich bags, resealable Ziploc® type bags, garbage bags, etc.), shrink-wrapping materials (eg food wraps, consumer product wraps) , Pallets and / or crate wraps), laminating films on food substrates, etc., which can be used in various film applications, especially disposable products, and as one of the disposal means An object of the present invention is to provide a film using a PHA composition that is biodegradable, that is, can be decomposed by microorganisms and is easy to dispose after use and excellent in environmental compatibility, and a method for producing the film.

  The present inventors paid attention to poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter referred to as PHBH), which has flexibility in the resin itself, with respect to the film made of the PHA composition, Furthermore, as a result of earnest research on gas barrier properties, it was found that a biodegradable resin film in which two kinds of specific PHA were mixed had both gas barrier properties such as oxygen and water vapor and flexibility, and completed the present invention. It came.

That is, the first of the present invention is the formula (1): [—CHR—CH ₂ —CO—O—] (R is an alkyl group represented by C _n H _{2n + 1} , and n = 1 to 15 is an integer. ) consisting of repeating units represented by (a) an aliphatic polyester (hereinafter, poly (3-hydroxyalkanoate), abbreviation: a film made of P3HA), (a) P3HA is, weight average molecular weight Mw _a (1 _{^{× 10 4 ≦ Mw a ≦ 3}} × 10 6), having a melting temperature Tm _{a (a)} and P3HA, the weight average molecular weight ^{_{Mw b (1 × 10 4 ≦}} Mw b ≦ 1 × 10 7), the melting temperature Tm _b ( here, it relates to a film which is characterized in that it consists with a _{Tm b ≧ Tm a + 5 ℃} ) (b) P3HA. A preferred embodiment relates to the film described above, wherein (a) P3HA is poly (3-hydroxybutyrate-co-3-hydroxyhexanoate, abbreviated as PHBH). More preferably, the composition ratio of the copolymerization component of PHBH is poly (3-hydroxybutyrate) / poly (3-hydroxyhexanoate) = 99/1 to 80/20 (mol / mol), and (B) The composition ratio of the poly (3-hydroxyhexanoate) component in the poly (3-hydroxybutyrate) and / or poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) is (3) a) The film as described above, which is smaller than P3HA, more preferably, the weight ratio of the content of (a) P3HA to the content of (b) P3HA is 80/20 to 99.1 / 0.1. The film described above, particularly preferably has a water vapor transmission coefficient of less than 3.0 × 10 ⁻² (g · m / m ² · 24 hr) according to JIS Z 0208 (40 ° C. · 90% RH). The film according to the above, characterized in that the oxygen transmission coefficient according to JIS K 7126 (20 ° C.) is less than 2.0 × 10 ⁻¹⁶ (mol · m / m ² · s · Pa). It relates to the above-mentioned film characterized.

  According to the present invention, a film having gas barrier properties such as oxygen and water vapor and flexibility can be obtained. By using this, for example in food applications, food bags (food storage bags, sandwich bags, resealable Ziploc (registered trademark) type bags, garbage bags, etc.), shrinkable packaging materials (for example, food wraps) , Consumer product wraps, pallets and / or crate wraps, etc.), laminating films on food substrates, etc., and can be used and used in various film applications, especially disposable products It is easy to dispose of later and has excellent environmental compatibility.

The present invention is represented by the formula (1): [—CHR—CH ₂ —CO—O—] (where R is an alkyl group represented by C _n H _{2n + 1} and n is an integer of 1 to 15). shown, (a) an aliphatic polyester copolymer (hereinafter, poly (3-hydroxyalkanoate), hereinafter referred to as "P3HA") a film consisting of, (a) P3HA is, weight average molecular weight Mw _a ( 1 × 10 ⁴ ≦ Mw _a ≦ 3 × 10 ⁶ ), (a) P3HA having _a melting temperature Tma, weight average molecular weight Mw _b (1 × 10 ⁴ ≦ Mw _b ≦ 1 × 10 ⁷ ), melting temperature Tm _{b (here, Tm b ≧ Tm a + 5} ℃) film film and characterized in that it consists with the (b) P3HA, a manufacturing method thereof.

<(A) P3HA>
(A) P3HA in the present invention is represented by formula (1): [—CHR—CH ₂ —CO—O—] (where R is an alkyl group represented by C _n H _{2n + 1} , and n = 1. It is an aliphatic polyester copolymer having a repeating structure of ˜15). The (A) P3HA of the present invention can be obtained by any of a method of producing from a microorganism or a chemical synthesis method, but a method of producing from a microorganism is preferred. In the chemical synthesis method, the molecular weight distribution of (A) P3HA is narrower than that produced from microorganisms, and unreacted monomer components, used polymerization initiators, and in the case of emulsion polymerization, emulsifiers remain in the system. As a result, physical properties may deteriorate. The (A) P3HA of the present invention is a composition comprising two types of polymers: (a) P3HA and (b) P3HA.

  In the present invention, the weight ratio of the content of (a) P3HA and the content of (b) P3HA is preferably (a) / (b) = 80/20 to 99.9 / 0.1. If (a) / (b) is larger than 99.9 / 0.1, the gas barrier property of the present invention may not be obtained. If it is smaller than 80/20, a gas barrier is obtained, The resin itself becomes brittle and a flexible film may not be obtained.

<(A) P3HA>
(A) of the present invention is represented by the formula (1): [—CHR—CH ₂ —CO—O—] (where R is an alkyl group represented by C _n H _{2n + 1} , and n = 1 to 15). Or a copolymer comprising two or more different combinations of n, di-copolymer, tri-copolymer, tetra-copolymer, etc., and at least one selected from the group The above can be used. Among them, n = 1 poly (3-hydroxybutyrate) (hereinafter referred to as PHB), n = 2 poly (3-hydroxyvalerate) (hereinafter referred to as PHV), n = 3 poly (3- Hydroxyhexanoate) (hereinafter referred to as PHH), n = 5 poly (3-hydroxyoctanoate) (hereinafter referred to as PHO), n = 15 poly (3-hydroxyoctadecanoate) (hereinafter referred to as “PHH”) , PHO _d ), or a copolymer comprising a combination of two or more types, that is, a di-copolymer, a tri-copolymer, or a blend thereof can be preferably used. More preferably, PHBH which is a copolymer of PHB and PHH can be used. The monomer composition ratio of PHBH is preferably 3HB / 3HH = 99/1 to 80/20 (mol / mol). More preferably, it is 98 / 2-85 / 15 (mol / mol), More preferably, it is 97 / 3-85 / 15 (mol / mol), Especially preferably, it is 95 / 5-85 / 15 (mol / mol). In general, the higher the composition ratio of 3HH, the more flexible the polymer properties of PHBH, but it seems that the effect of gas barrier properties decreases with decreasing crystallinity. In the present invention, if 3HB / 3HH (mol / mol) in PHBH is less than 80/20 (mol / mol), the crystallinity may be lowered, and if it exceeds 99/1 (mol / mol), crystallization occurs. The degree may increase too much and the resin may become brittle.

  PHBH in the present invention may be obtained by any of a method of producing from a microorganism or a chemical synthesis method, and is not particularly limited. Among these, PHBH produced from microorganisms is preferable in that PHBH can be obtained by culturing microorganisms using fats and oils as raw materials, and the process is simple and inexpensive compared to chemical synthesis methods. Further, PHBH produced from microorganisms is preferable in that the molecular weight distribution of PHBH is broader than that of PHBH obtained by a chemical synthesis method, and 3HB and 3HH are appropriately and nonuniformly polymerized. Furthermore, PHBH obtained by a chemical synthesis method may have unreacted monomer components, used polymerization initiators, and in the case of emulsion polymerization, emulsifiers and the like remain in PHBH, resulting in a decrease in physical properties.

  The microorganism that produces PHBH is not particularly limited as long as it is a microorganism that accumulates PHBH in a cell. Alkigenes, such as A. lipolytica, A. eutrophus, A. latus, Pseudomonas, Examples include Bacillus, Azotobacter, Nocardia and Aeromonas. Among them, in terms of efficiently producing PHBH, Alcaligenes eutrophus AC32 (FERM BP-6038) (J. Bacteriol., 179, 4821) in which a strain such as A. caviae, and further, a gene of PHA synthase group has been introduced. -4830 (1997)) is more preferable, and microbial cells obtained by culturing these microorganisms under appropriate conditions and accumulating PHBH in the cells are used.

(A) P3HA of the present invention has a weight average molecular weight ^{_{Mw a (1 × 10 4 ≦}} Mw a ≦ 3 × 10 6), and having a melting temperature Tm _a. Here, the melting temperature is equal to or higher than the assumed melting temperature at which the resin is sufficiently melted from 30 ° C. at a heating rate of 10 ° C./min using a differential scanning calorimeter (hereinafter referred to as DSC). Then, the temperature is lowered to 30 ° C. at a rate of 10 ° C./min, and then raised again to the expected melting temperature of the resin at which the resin is sufficiently melted at a rate of 10 ° C./min+50 to 60 ° C. It is the peak top temperature of the endothermic curve when The endothermic curve peak when the temperature is raised again shows one or a plurality of peaks. In the case of a plurality of peaks, the peak top temperature on the high temperature side is taken as the melting temperature. If Mw _a is 1 × 10 ⁴ less may (A) poor melt tension of P3HA, is not obtained, such as line speed improvement effect during extrusion. In the case of Mw _a> 3 × 10 ⁶ may take the load to the extruder is too high melt viscosity, poor itself productivity culturing such resin, the resulting resin becomes high price Therefore, it is not preferable. However, even when the molecular weight is too high, it can be adjusted to an appropriate molecular weight by appropriately adjusting the heating temperature and time. It should be noted that when the heating temperature, time, and shear rate are constant, (a) the molecular weight reduction rate of P3HA can always be reproduced.

<(B) P3HA>
(B) of the present invention is represented by the formula (1): [—CHR—CH ₂ —CO—O—] (where R is an alkyl group represented by C _n H _{2n + 1} , and n = 1 to 15) or a copolymer composed of a combination of two or more different n, that is, a di-copolymer, a tri-copolymer, a tetra-copolymer, etc., and selected from these groups At least one or more can be used. Among them, a PHB with n = 1, a PHV with n = 2, a PHH with n = 3, a PHO with n = 5, a homopolymer with n = 15 PHO _d , or a copolymer composed of a combination of two or more. Di-copolymers, tri-copolymers, etc., or blends thereof can be preferably used. More preferably, PHBH which is a copolymer of PHB and PHH can be used. Considering from the performance of imparting gas barrier properties, the composition ratio in the PHBH is preferably 3HB / 3HH = 99/1 to 90/10 (mol / mol). More preferably, (a) P3HA is also PHBH, and the composition ratio of 3HH component in PHBH is smaller than (a) the composition ratio of 3HH component in PHBH which is P3HA. The PHBH can be obtained in the same manner as the method described in the section <(a) P3HA>.

  As described above, (b) P3HA is introduced to impart gas barrier properties to (A) P3HA. The gas barrier property mentioned here means the impermeability of low-molecular substances such as gas, water vapor, and organic vapor. Even if it is said to be impermeable, the plastic film is permeable to low-molecular substances, although the degree is different, so that a film having a small property has gas barrier properties. In the present invention, by mixing (b) P3HA with (a) P3HA, a film having suppressed permeability to oxygen and water vapor can be obtained. Although the mechanism for imparting gas barrier properties is not clear, (b) P3HA used in the present invention has a composition ratio of 3HH component in PHBH smaller than (a) P3HA, and (a) crystallinity is higher than P3HA. Since high PHBH is used, it is presumed that (b) P3HA is uniformly dissolved and finely dispersed in (a) P3HA, which leads to further effect of imparting gas barrier properties.

The (b) P3HA of the present invention preferably has a weight average molecular weight (Mw _b ) of 1 × 10 ⁴ ≦ Mw _b ≦ 1 × 10 ⁷ . When Mw _b is smaller than 1 × 10 ⁴ , (A) P3HA has poor melt tension, and may not have the effect of improving the line speed during extrusion. Further, the Mw _b is greater than 1 × 10 ^7, may take the load to the extruder is too high melt viscosity, poor itself productivity culturing such resin, the resulting resin has a high price Therefore, it may not be preferable. However, even when the molecular weight is too high, it can be adjusted to an appropriate molecular weight by appropriately adjusting the heating temperature and time. It should be noted that when the heating temperature, time, and shear rate are constant, the molecular weight reduction rate of PHA can always be reproduced.

Further, (a) P3HA and (b) P3HA is the relationship between the melting temperature Tm _a and Tm _b corresponding to satisfy _{Tm b ≧ Tm a + 5 ℃} , i.e. (b) melting of P3HA and (a) P3HA Those having a temperature difference of 5 ° C. or more are preferred. This melting temperature difference is preferably 10 ° C. or higher, more preferably 20 ° C. or higher. When Tm _b <Tm _a + 5 ° C., (a) a large effect may not be obtained in terms of gas barrier properties as compared with P3HA alone. Here, the melting temperature is a value measured in the same manner as in the method described in the section <(a) P3HA>.

<(A) Film made of P3HA>
As an embodiment of the present invention, a film which is a plastic product can be exemplified. “Film” herein refers to a very thin continuous piece with a large ratio of length to thickness and a large ratio of width to thickness. Although there is no condition for a clear upper limit of the thickness, the preferable upper limit is 1 mm or less, more preferably 0.5 mm or less, still more preferably 0.2 mm or less, and particularly preferably 0.1 mm or less.

Moreover, it is preferable that the water vapor permeability coefficient is less than 3.0 × 10 ⁻² (g · m / m ² · 24 hr) as an index of water vapor permeability of the film made of (A) P3HA of the present invention. Here, the water vapor transmission coefficient is based on the JIS Z 0208 standard (moisture-proof packaging material moisture permeability test method), measured at a test temperature of 40 ° C. and a humidity of 90%, and measured the water vapor permeability of the film to be tested. The value multiplied by. Water vapor permeability coefficient, 2.0 × more preferably less than 10 ^{-2 (g · m / m 2} · 24hr), more preferably less than ^{1.0 × 10 -2 (g · m} / m 2 · 24hr), 5 Less than 0.0 × 10 ⁻³ (g · m / m ² · 24 hr) is particularly preferable. The water vapor permeability is substantially inversely proportional to the thickness. In the present invention, the water vapor permeability is evaluated by a water vapor permeability coefficient converted to a permeation amount per unit thickness. For example, if the film thickness is 100 μm (0.1 mm) and the water vapor transmission rate is 200 (g / m ² · 24 hr), the water vapor transmission coefficient converted to the permeation amount per unit thickness is 0.02 (g · m / M ² · 24 hr) or 20 (g · mm / m ² · 24 hr), which falls within the scope of the present invention. In addition, examples of resins exhibiting good gas barrier properties include ethylene vinyl acetate resin films and amide-based nylon resin films, but they have water vapor permeability at the same level as compared with them.

Further, as an index of oxygen permeability of the film made of (A) P3HA of the present invention, the oxygen permeability coefficient is preferably 2.0 × 10 ⁻¹⁶ (mol · m / m 2 · s · Pa) or less. Here, the oxygen permeability coefficient is based on JIS K 7126 standard (gas permeability test method for plastic films and sheets), test temperature: 20 ° C., and oxygen gas permeability is measured according to A method (differential pressure method), The value multiplied by the film thickness. The oxygen permeability coefficient is more preferably less than 1.0 × 10 ⁻¹⁶ (mol · m / m ² · s · Pa), and less than 5.0 × 10 ⁻¹⁷ (mol · m / m ² · s · Pa). Further preferred. The oxygen permeability is substantially inversely proportional to the thickness. In the present invention, the oxygen permeability is evaluated by the oxygen permeability coefficient converted to the permeation amount per unit thickness. For example, if the film thickness is 100 μm (0.1 mm) and the oxygen permeability is 1.0 × 10 ⁻¹² (mol / m ² · s · Pa), the oxygen permeability coefficient converted to the permeation amount per unit thickness. Is 1.0 × 10 ⁻¹⁶ (mol · m / m ² · s · Pa) or 1.0 × 10 ⁻¹³ (mol · mm / m ² · s · Pa), which falls within the scope of the present invention. . In comparison with other general-purpose resins, it is at the same level as an ethylene vinyl acetate resin film or an amide nylon resin film, and has better oxygen permeability than a polyolefin resin film or a polystyrene resin film.

<(A) Manufacturing Method of Film Consisting of P3HA>
The mixing method of (a) P3HA and (b) P3HA of the present invention is not particularly limited, and may be used as necessary. For example, a dry blend method using a Henschel mixer, a kneader, a melt-kneading roll, a melt-extruding method in advance, or (a) in a slurry obtained in the culture or purification stage of microorganisms producing P3HA (b ) A method of mixing P3HA. (A) From the point that (b) P3HA is uniformly mixed and finely dispersed in P3HA, for example, a melt kneading method using a twin screw type screw extruder, (a) P3HA and (b) melting of P3HA A method of melting and kneading for a short time at a temperature not lower than the temperature at a temperature that is not significantly pyrolyzed, or (a) a method of mixing P3HA in a slurry obtained during cultivation or purification of microorganisms that produce P3HA is preferable. .

  Moreover, the film obtained by this invention is not a method specifically limited, It can manufacture as needed suitably. For example, there is a melt extrusion method used when film-forming general-purpose thermoplastic plastics such as polyethylene, polypropylene, polystyrene, etc., but it is wide with a narrow slit-like space at the tip of the extruder as necessary. Examples of the method include forming a film by attaching a T-type die (T-type die method), a ring die having a ring-like interval (inflation method), or the like. Moreover, the film formation by the calendar method often used when film-forming vinyl chloride resin and polyethylene oxide resin is mentioned. Calendar molding is a method of rolling a resin between rolls to make a film, but there are linear three-roll type, reverse L type, Z type, etc. due to different roll arrangements, as required You can choose the type of roll.

  In addition, a casting method using a solvent, an emulsion method, a laminating method by laminating with a resin, a co-extrusion method, and the like can be mentioned. These methods may be used as necessary. In addition, the film can be stretched and oriented in two longitudinal and / or lateral directions, and any processing method that is carried out at the time of forming a general-purpose plastic film may be used.

  The thickness of the film of the present invention can be adjusted as necessary, but in order to further impart gas barrier properties, a resin layer having gas barrier properties such as nylon resin and ethylene vinyl acetate copolymer. It is also possible to adjust the thickness by combining lamination with the above.

  The (A) P3HA of the present invention includes, as necessary, colorants such as pigments and dyes, fillers such as inorganic or organic particles, glass fibers, whiskers and mica, antioxidants, ultraviolet absorbers and the like. Stabilizers, plasticizers, lubricants, mold release agents, water repellents, antibacterial agents and other secondary additives can be contained.

  Next, although the biodegradable resin composition of this invention and its manufacturing method are demonstrated in detail based on an Example, this invention is not restrict | limited only to this Example. Unless otherwise specified, “parts” represents parts by weight and “%” represents% by weight. The evaluation methods implemented in the examples are as follows. The results are summarized in Table 1.

<Measuring method of melting temperature (Tm)>
Using Seiko Denshi Kogyo DSC200, (a) P3HA, (b) P3HA 1 to 10 mg, respectively, at a rate of temperature increase of 10 ° C / min from 30 ° C to composition (a), gas barrier property-imparting agent (b) The melting temperature (Tm _a ) and (Tm _b ) accompanying the crystal melting of (a) P3HA and (b) P3HA were recorded.

<Method for measuring weight average molecular weight (Mw)>
The Mw values of (a) P3HA and (b) P3HA were determined by GPC measurement in terms of polystyrene. The GPC device is a CCP & 8020 system (Tosoh), the column is GPC K-805L (Showa Denko), the column temperature is 40 ° C., and 20 μl of 20 mg resin composition dissolved in 10 ml chloroform is injected. , Mw was determined.

<Evaluation method of water vapor permeability (gas barrier property) of film>
Using the films obtained in the following Examples and Comparative Examples, the water vapor permeability was measured in accordance with JIS Z 0208 (moisture-proof packaging material moisture permeability test method). At that time, the test temperature was recorded at 40 ° C. and humidity of 90% at each film thickness, and the unit was recorded in g / m ² · 24 hr. The water vapor transmission coefficient (g · m / m ² · 24 hr), which is the water vapor transmission amount per unit film thickness multiplied, was converted again, and the water vapor permeability was evaluated according to the following criteria. In addition, if it does not permeate | transmit water vapor | steam, barrier property is favorable and should show a numerically low value. The evaluation criteria are as follows. A: 0 (g · m / m ² · 24 hr) or more to less than 1.0 × 10 ⁻² (g · m / m ² · 24 hr), ○: 1.0 × 10 ⁻² (g · m / m ²⁾ 24 hr) to 3.0 × 10 ⁻² (g · m / m ² · 24 hr), Δ: 3.0 × 10 ⁻² (g · m / m ² · 24 hr) to 1.0 × 10 Less than ^-1 (g · m / m ² · 24 hr).

<Oxygen permeability (gas barrier property) evaluation method of film>
Using the films obtained in the following examples and comparative examples, the oxygen permeability was measured in accordance with JIS K 7126 standard (gas permeability test method for plastic film and sheet). At that time, the test temperature: 20 ° C., A method (differential pressure method), each film thickness, the unit is recorded in mol / m ² · s · Pa, and the unit film thickness is shown in the table for both Examples and Comparative Examples. The oxygen permeability was converted into an oxygen permeation coefficient (mol · m / m ² · s · Pa) which is a permeation amount of oxygen permeation, and oxygen permeability was evaluated. It should be noted that if it is impermeable to oxygen, the barrier property is good, and it is good to show a numerically low value. The evaluation criteria are as follows. A: 0 (mol · m / m ² · s · Pa) or more to less than 1.0 × 10 ⁻¹⁶ (mol · m / m ² · s · Pa), ○: 1.0 × 10 ⁻¹⁶ (mol · m / m ² · s · Pa) or more to less than 2.0 × 10 ⁻¹⁶ (mol · m / m ² · s · Pa), Δ: 2.0 × 10 ⁻¹⁶ (mol · m / m ² · s)・ Pa) or more to less than 3.0 × 10 ⁻¹⁶ (mol · m / m ² · s · Pa).

<Film tensile test (resin film flexibility evaluation)>
Using the films obtained in the following examples and comparative examples, after punching into No. 2 type dumbbell shape, using INSTRON 5582 type tester (Instron), JIS K 7127 standard (Test of tensile properties of plastic) The tensile elongation was measured according to (Method). At that time, the tensile elongation was measured at a test temperature: 23 ° C., a test speed: 5 mm / min, a gripping tool: 1 kN capacity air chuck, and a distance between gripping chucks: 80 mm, and the flexibility was evaluated from the tensile elongation. Did. Here, as an index indicating the flexibility of the resin, the tensile elongation is particularly large, and the better the elongation is, the more flexible the effect of the present invention is. The evaluation criteria are as follows. A: Good flexibility that stretches well when the tensile elongation is 100% or more, B: Flexibility that stretches when the tensile elongation is 50% or more to less than 100%, Δ: Tensile elongation is 5% From above to less than 50%, which is not particularly good elongation but normal flexibility, x: Tensile elongation is less than 5% and is hard and brittle.

<Evaluation of biodegradability>
The resin films obtained in Examples and Comparative Examples were cut into a dumbbell shape having a length of 115 × width of 25 (mm), buried in a soil having a depth of 10 cm, and after 6 months, the shape change was observed, and the degradability was improved. Evaluation was made according to the following criteria. ○: Decomposition so that the shape cannot be confirmed, Δ: Substantially partially decomposed, but the shape can be confirmed somehow, ×: Almost no change in shape, and no decomposition.

(Production Example 1) Production of P3HA-1 pellet Produced using Alcaligenes eutrophus AC32 (J. Bacteriol., 179, 4821 (1997)) in which PHA synthase gene derived from Aeromonas caviae was introduced into Alcaligenes eutrophus as a microorganism. (a) P3HA (PHBH composition, 3HB / 3HH = 88.3 / 11.7 (mol / mol), Tm a = 110 ℃, Mw a = 100 50,000) and 97 parts by weight, PHB powder as (b) P3HA ( Mitsubishi Gas Chemical, Biogreen, Tm _b = 176 ° C., Mw _b = 600,000) After dry blending 3 parts by weight, using a single screw extruder (Kasamatsu Lab Lab universal extruder, screw diameter = 35 mm), Only in one zone of the cylinder part is set to a melt kneading temperature of 190 ° C., resin supply side cylinder, die head part 120 to 140 ° C., screw rotation speed 50 rpm, resin discharge rate 3 kg / hr Then, an extruded strand was obtained, and (a) P3HA (hereinafter, P3HA-1) pellets were obtained by cutting using a warm water bath and pelletizer adjusted to 60 ° C. near the maximum crystallization temperature of P3HA.

(Production Example 2) Production of P3HA-2 pellets (a) The amount of P3HA used was 80 parts by weight, and (b) 20 parts by weight of PHB powder was used as P3HA. ) P3HA (hereinafter P3HA-2) pellets were obtained.

(Production Example 3) Production of P3HA-3 pellets (b) Other than using PHBH (3HB / 3HH = 96.8 / 3.2 (mol / mol), Tm _b = 152 ° C., Mw _b = 1,070,000) as P3HA Obtained (A) P3HA pellets (hereinafter referred to as P3HA-3) in the same manner as in Example 1.

(Production Example 4) P3HA-4 pellets prepared in (a) as P3HA PHBH (3HB / 3HH = 91.5 / 8.5 ( _{mol%), Tm a = 140 ℃} , Mw a = 102 50,000) except for using Were the same as in Example 1 to obtain (A) P3HA (hereinafter, P3HA-4) pellets.

Using the preparation of (Production Example 5) P3HA-5 pellets (a) P3HA (PHBH composition, 3HB / 3HH = 88.3 / 11.7 (mol / mol), Tm a = 110 ℃, Mw a = 100 50,000) The amount was 60 parts by weight, and (b) P3HA (hereinafter P3HA-5) pellets were obtained in the same manner as in Example 1 except that 40 parts by weight of PHB powder was used as P3HA.

(Production Example 6) P3HA-6 Preparation of pellets (a) P3HA (PHBH composition, 3HB / 3HH = 96.8 / 3.2 ( _{mol%), Tm a = 152 ℃} , Mw a = 107 50,000) the amount of Was 60 parts by weight, and (b) P3HA (hereinafter, P3HA-6) pellets were obtained in the same manner as in Example 1 except that 40 parts by weight of PHB powder was used as P3HA.

(Example 1) Production and evaluation of a film composed of P3HA-1 Using a P3HA-1 pellet, a single-screw extruder with a downward T-type die (Toyo Seiki Seisakusho Lab Plast Mill Extruder “2D20C type”, screw diameter = 30 mm, set barrel die temperature: C1 / C2 / C3 / D = 120/120/130/140 ° C., discharge amount: 1.0 kg / Hr), and downward direction T adjusted to a die gap width of 0.5 mm A film made of (A) P3HA is extruded from the die die tip and immediately brought into contact with a metal roll heated at 60 ° C. to adjust the thickness to 50 to 200 μm. The film was wound up. The obtained film measured each physical property value according to the said evaluation method. The evaluation results are shown in Table 1.

Example 2 Production and Evaluation of Film Consisting of P3HA-2 Using P3HA-2 pellets, a film was obtained in the same manner as in Example 1, and each physical property value was measured according to the evaluation method. The evaluation results are shown in Table 1.

(Example 3) Production and evaluation of a film made of P3HA-3 Example using P3HA-3 pellets except that the barrel temperature was set to C1 / C2 / C3 / D = 150/150/160/170 ° C. A film was obtained in the same manner as in Example 1, and each physical property value was measured according to the evaluation method. The evaluation results are shown in Table 1.

(Example 4) Production and evaluation of a film composed of P3HA-4 Example except that P3HA-4 pellets were used and the barrel temperature was set to C1 / C2 / C3 / D = 140/140/150/155 ° C. A film was obtained in the same manner as in Example 1, and each physical property value was measured according to the evaluation method. The evaluation results are shown in Table 1.

Example 5 Production and Evaluation of Film Consisting of P3HA-5 Using P3HA-5 pellets, set barrel die temperature: set barrel die temperature: C1 / C2 / C3 / D = 180/180/185/190 ° C. Except for the above, a film was obtained in the same manner as in Example 1, and each physical property value was measured according to the evaluation method. The evaluation results are shown in Table 1.

Example 6 Production and Evaluation of Film Consisting of P3HA-6 Using P3HA-6 pellets, set barrel die temperature: set barrel die temperature: C1 / C2 / C3 / D = 180/180/185/190 ° C. Except for the above, a film was obtained in the same manner as in Example 1, and each physical property value was measured according to the evaluation method. The evaluation results are shown in Table 1.

(Production Example 7) Production of P3HA-7 pellets (b) P3HA (hereinafter referred to as P3HA-7) was carried out in the same manner as in Example 1 except that P3HA was not used and all the melting temperatures during pelletization were performed at 120 ° C. Pellets were obtained.

(Production Example 8) Preparation of P3HA-8 pellets (a) P3HA, (b) As P3HA, only PHB powder (Mitsubishi Gas Chemical Co., Biogreen, Tm _b = 176 ° C, Mw _b = 600,000) was used for pelletization. P3HA (hereinafter referred to as P3HA-8) pellets were obtained in the same manner as in Example 1 except that all melting temperatures were 190 ° C.

(Comparative Example 1) Production and Evaluation of Film Consisting of P3HA-7 An Example except that P3HA-7 pellets were used and the barrel temperature was set to C1 / C2 / C3 / D = 120/120/130/140 ° C. A film was obtained in the same manner as in Example 1, and each physical property value was measured according to the evaluation method. The evaluation results are shown in Table 1.

(Comparative Example 2) Production and Evaluation of Film Consisting of P3HA-8 Example except that P3HA-8 pellets were used and the barrel / die temperature was set to C1 / C2 / C3 / D = 180/180/185/190 ° C. A film was obtained in the same manner as in Example 1, and each physical property value was measured according to the evaluation method. The evaluation results are shown in Table 1.

  In Examples 1 to 4, the film obtained by Examples has a melting temperature Tm and a weight average molecular weight Mw that satisfy the preferable conditions of the present invention, and satisfies both the gas barrier property and flexibility of the present invention. Is. Examples 5 and 6 have a melting temperature Tm and a weight average molecular weight Mw that satisfy the preferred conditions of the present invention, and the films obtained by the examples are somewhat inferior in flexibility, but the gas barrier properties of the present invention. Is remarkably expressed. On the other hand, the film of Comparative Example 1 is not mixed with a gas barrier property-imparting agent that can also be a crystal nucleating agent. And a good film could not be obtained. Further, the film of Comparative Example 2 is the use of the resin alone as in Comparative Example 1, and the resulting film has good gas barrier properties, but the film has a tensile elongation of 3% and hardly stretches. It is a hard and brittle film. Moreover, the biodegradability of the film was good in both Examples and Comparative Examples.

Claims (6)

It consists of a repeating unit represented by the formula (1): [—CHR—CH ₂ —CO—O—] (R is an alkyl group represented by C _n H _{2n + 1} and n is an integer of 1 to 15) ( a) aliphatic polyesters (hereinafter, poly (3-hydroxyalkanoate), abbreviation: P3HA) composed of a film from, (a) P3HA is, weight average molecular weight ^{_{Mw a (1 × 10 4 ≦}} Mw a ≦ 3 × 10 ^6), having a melting temperature Tm _a and (a) P3HA, the weight average molecular weight ^{_{Mw b (1 × 10 4 ≦}} Mw b ≦ 1 × 10 7), the melting temperature Tm _b (where, Tm _b ≧ Tm _a +5 (B) a film comprising P3HA.   The film according to claim 1, wherein (a) P3HA is poly (3-hydroxybutyrate-co-3-hydroxyhexanoate, abbreviation: PHBH).   The composition ratio of the copolymer component of PHBH is poly (3-hydroxybutyrate) / poly (3-hydroxyhexanoate) = 99/1 to 80/20 (mol / mol), and (b) P3HA The composition ratio of the poly (3-hydroxyhexanoate) component in the poly (3-hydroxybutyrate) and / or poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) is greater than (a) P3HA The film according to claim 1, wherein the film is also small.   The film according to any one of claims 1 to 3, wherein a weight ratio of the content of (a) P3HA and the content of (b) P3HA is 80/20 to 99.1 / 0.1. 5. The water vapor transmission coefficient according to JIS Z 0208 (40 ° C./90% RH) is less than 3.0 × 10 ⁻² (g · m / m ² · 24 hr). The film according to item. 6. The oxygen permeation coefficient according to JIS K 7126 (20 ° C.) is less than 2.0 × 10 ⁻¹⁶ (mol · m / m ² · s · Pa). The film described.