JP2007002105A - Biodegradable resin composition and film or sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable resin composition which has good transparency, flexibility and weather resistance, is free from the deterioration of the transparency by the bleeding-out of an anti-fogging agent with the passage of time, has excellent anti-fogging durability, and little gives loads to environments, and to provide a film or sheet suitable for agriculture and food packaging. <P>SOLUTION: This biodegradable resin composition is characterized by comprising 100 pts.mass of a biodegradable polyester resin, 0.1 to 5.0 pts.mass of an ester of a fatty acid with an alcohol selected from sorbitol, sorbitan, and polyglycerol (including dehydration-condensed alcohols, and polyhydric alcohol alkylene oxide adduct) as the anti-fogging agent, and 0.05 to 2.5 pts.mass of a sulfonate-based surfactant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a biodegradable resin composition and film or sheet excellent in transparency and antifogging properties, and more particularly to a biodegradable resin composition and film or sheet suitable as agricultural or food packaging materials.

  In today's daily life, plastics (synthetic resins) such as polyethylene, polystyrene, polypropylene, and polyvinyl chloride are used in a wide variety of fields such as food packaging, building materials, and home appliances, and are indispensable for daily life. It is something that can not be.

  The most important characteristic of plastic is its durability, but when it becomes waste after its mission, its good durability is inferior to natural degradation and affects biological systems. It has a negative aspect that causes environmental destruction.

  Biodegradable plastics (biodegradable resin compositions) are attracting attention in order to overcome such drawbacks of plastics. Recycling of plastic products has been regulated by the growing awareness of environmental issues in recent years, and so-called biodegradable plastics that can be easily decomposed in the environment along with recycling and reuse have attracted attention. Is poured. In particular, it is expected to be used in agricultural films and sheets used in the environment and food packaging films and sheets that require high safety.

As agricultural films, biodegradable plastics have begun to be applied to agricultural multi-films, but in film and sheets for agricultural houses and coverings, mechanical properties, transparency, weather resistance and anti-fogging properties Resins that can satisfy such performance are being pursued.
For improving flexibility and impact resistance, a method for producing a biodegradable agricultural film in which polylactic acid and biodegradable polyester are blended at a specific ratio is known (for example, see Patent Documents 1 and 2). However, its transparency is low and it cannot be used as an agricultural house or covering material.

In applications such as agricultural houses and covering materials, it is possible to add a dripping agent or an antifogging agent to prevent damage to the production crops due to the impairing of sunlight due to water droplets adhering to the plastic surface and falling of water droplets. Usually done. For the purpose of improving transparency and antifogging property, a method of blending a small amount of polybutylene terephthalate resin with a biodegradable aliphatic aromatic polyester resin is known (for example, see Patent Document 3). In the film containing the antifogging agent described in (1), the antifogging agent bleeds out vigorously, and the film becomes white and turbid after several days of film production, which is difficult to use in practice. Further, it is known to use a nonionic surfactant in combination as a lubricant and an antifogging agent in a polylactic acid film (for example, see Patent Document 4), but satisfactory antifogging properties are not obtained.
JP 2004-147613 A JP 2003-105183 A JP 2004-352799 A JP-A-9-286908

  By including the specific antifogging agent according to the present invention in the biodegradable polyester resin, there is no hindrance to transparency due to bleeding out of the antifogging agent, and it is transparent with excellent initial antifogging property and antifogging durability. It becomes possible to supply a flexible biodegradable resin composition, an agricultural film formed by molding the same, and a film or sheet suitable for food packaging.

  An object of the present invention is a biodegradable resin with low environmental impact, having transparency, flexibility and weather resistance, having no hindering of transparency due to bleed-out of the antifogging agent over time and having excellent antifogging durability. It is providing the film or sheet | seat suitable for a composition, agricultural use, and food packaging.

The present invention for solving the above problems has the following configuration.
1. An ester of an alcohol selected from sorbitol, sorbitan, and polyglycerin as an antifogging agent (including dehydrated condensed alcohol and an alkylene oxide adduct of a polyhydric alcohol) and a fatty acid with respect to 100 parts by mass of the biodegradable polyester resin. A biodegradable resin composition comprising 0.1 to 5.0 parts by mass and 0.05 to 2.5 parts by mass of a sulfonate surfactant.

2. The biodegradable polyester resin is a polyester obtained by polycondensing a diol containing at least one of ethylene glycol and 1,4-butanediol with a dicarboxylic acid containing at least one of terephthalic acid and adipic acid. 2. The biodegradable resin composition as described in 1 above.

3. 2. The biodegradable resin composition as described in 1 above, wherein the biodegradable polyester resin is a lactic acid-based polyester.

4). Any one of the above 1-3, wherein the esterification rate is 10 to 90% when the ratio of the hydroxyl group esterified with a fatty acid in the hydroxyl group of the polyhydric alcohol is defined as the esterification rate. The biodegradable resin composition as described.

5. A film or sheet formed from the biodegradable resin composition according to any one of 1 to 4 above.

The present invention will be described in more detail.
The present invention is directed to biodegradable polyester resins. Known biodegradable polyester resins can be used. The structure of the polyester can be broadly classified into those in which diols and dicarboxylic acids are alternately polymerized as monomers and polymers of hydroxycarboxylic acids. Polyester monomer diols that can be used in the present invention include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol. 1,4-benzenedimethanol, and polymers thereof. Examples of the dicarboxylic acid include succinic acid, oxalic acid, malonic acid, maleic acid, fumaric acid, adipic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanedioic acid, isophthalic acid, terephthalic acid and the like. Examples of the hydroxycarboxylic acid include L-lactic acid, D-lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, and 6-hydroxycaproic acid. These can be used alone or in combination of two or more.

  These monomers can be selected without particular limitation as long as they have biodegradability. Since the present invention aims to prevent fogging due to adhesion of water droplets during use, a highly transparent polyester is preferred. Containing at least one of ethylene glycol and 1,4-butanediol as diol, and at least one of terephthalic acid and adipic acid as dicarboxylic acid, and polycondensing them, mechanical properties, transparency, biodegradation It has a good balance of properties and is preferable.

  The biodegradable polyester resin of the present invention is also preferably a lactic acid-based polyester and may be intended for polylactic acid.

The polylactic acid resin used does not ask | require the polymerization degree or quality. The lactic acid monomer used in the polylactic acid resin can be used without particular limitation even if it is D-form or L-form. Further, not only a polymer composed only of L-lactic acid or D-lactic acid, but also a copolymer such as glycolic acid, ε-caprolactone, trimethylene carbonate or polyethylene glycol may be used in combination. In addition, other biodegradable polymers such as cellulose acetate, polycaprolactone, polybutylene succinate, polyhydroxybutyrate and valerate copolymer, chitin, chitosan or starch can be used as long as the physical properties of the polylactic acid resin are not impaired. You may mix | blend.
Moreover, you may use a copolymer other than the above in the range which does not impair the objective of this invention. For example, impact resistance may be enhanced by mixing an ethylene / glycidyl methacrylate copolymer in a ratio of 4: 1 to polylactic acid.

  There is no restriction | limiting in particular as a manufacturing method of the biodegradable polyester resin used for this invention, It can manufacture using a well-known method. Examples thereof include direct polycondensation of diol and dicarboxylic acid, direct polycondensation of hydroxycarboxylic acid, and ring-opening polymerization using a cyclic or cyclic dimer of hydroxycarboxylic acid. During polymerization, a branched chain may be introduced by copolymerizing a polyfunctional monomer such as glycerin, polyglycerin, pentaerythritol, citric acid, tartaric acid or malic acid. Further, isocyanate compounds, epoxy compounds, aziridine compounds, carbodiimide compounds, oxazoline compounds, azo compounds, polyvalent metal compounds, polyfunctional phosphates, phosphites, and the like may be used as chain extenders.

  The antifogging agent used in the present invention is composed of a combination of an ester composed of a polyhydric alcohol and a fatty acid and a sulfonate surfactant. Examples of the polyhydric alcohol that can be used for an ester composed of a polyhydric alcohol and a fatty acid include ethylene glycol, propylene glycol, isosorbide, glycerin, trimethylolpropane, erythritol, pentaerythritol, sorbitan, xylitol, sorbitol, and sucrose. In addition, dehydration condensation alcohols of these polyhydric alcohols can also be used. Examples of the dehydrated condensed alcohol include polyglycerin and polypentaerythritol.

  Furthermore, alcohols obtained by adding alkylene oxide to these polyhydric alcohols can also be used. Two or more kinds of these polyhydric alcohols may be used. Among these, sorbitol, sorbitan, polyglycerin, sorbitol ethylene oxide adduct, sorbitan ethylene oxide adduct, sorbitan propylene oxide adduct, polyglycerin ethylene oxide adduct, and esters of fatty acids with initial antifogging and continuous antifogging properties. It is excellent in safety, has little hindering of transparency, and has high safety, which is preferable.

  Fatty acids that can be used for esters composed of polyhydric alcohols and fatty acids are not particularly limited, but are saturated fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid Unsaturated fatty acids such as linolenic acid and erucic acid can be used. As these fatty acids, two or more kinds of mixed fatty acids may be used.

  An ester composed of a polyhydric alcohol and a fatty acid can be produced by a known ester reaction. For example, it can be produced by a direct esterification reaction between a polyhydric alcohol and a fatty acid or a transesterification reaction between a polyhydric alcohol and an oil. In the present invention, the esterification rate is preferably 10% or more and 90% or less, when the ratio of the hydroxyl group esterified with a fatty acid in the hydroxyl group of the starting polyhydric alcohol is defined as the esterification rate. More preferably, it is 10% or more and 50% or less. When the esterification rate is less than this range, the compatibility with the resin is low and bleeding tends to occur. Moreover, when the esterification rate exceeds this range, the hydrophilicity becomes low and antifogging properties are hardly exhibited.

  Examples of the sulfonate surfactant used in the present invention include sodium dodecylbenzenesulfonate, calcium dodecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium α-olefinsulfonate, sodium dioctylsulfosuccinate, sodium dihexylsulfosuccinate. , Sodium ditridecyl sulfosuccinate, disodium lauryl sulfosuccinate, sodium linear alkylbenzene sulfonate, sodium alkyl sulfonate, and the like. Of these, sodium alkyl sulfonate is particularly preferable from the viewpoint of achieving the object of the present invention.

  In this invention, the compounding quantity with respect to biodegradable polyester-type resin of ester which consists of a polyhydric alcohol and a fatty acid is 0.1-5 mass parts with respect to 100 mass parts of resin, Preferably it is 0.5-3 mass parts. Range. When below this range, the target performance of the present invention is insufficient, and when above this range, the transparency of the molded product is impaired, or bleeding of the antifogging agent is observed.

  In this invention, the compounding quantity with respect to biodegradable polyester-type resin of a sulfonate surfactant is in the range of 0.05-2.5 mass parts with respect to 100 mass parts of resin. When below this range, the target performance of the present invention is insufficient, and when above this range, the physical properties and transparency of the molded product are impaired, and bleeding of the antifogging agent is observed.

  Further, the biodegradable resin composition of the present invention may be used together with additives such as stabilizers, plasticizers, antistatic agents, antioxidants, lubricants, slip agents, antifoggants, and the like. Can be used in combination as long as the effects of the present invention are not impaired.

  The biodegradable resin composition of the present invention can be compounded with additives such as resin and antifogging agent using an extruder, a Banbury mixer, etc., which are used for ordinary plastic compounding. In the case of polymer blending, a twin screw extruder is preferred. Moreover, you may add an additive to a biodegradable resin composition previously by the masterbatch method which produces the resin composition which contains an additive in high concentration. The prepared compound or master batch is blended so as to have a predetermined concentration, and formed into a sheet or a film by T-die, inflation or the like. The film may be either stretched or unstretched.

Hereinafter, the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited thereto.
The evaluation method for each evaluation item will be described below.
Evaluation is performed by putting water at the temperature shown below into a water tank, covering the prepared film with a 100 × 100 mm window test box having an inclination of 30 degrees for evaluation, and stopping with cellophane tape. The anti-fogging property, film bleeding and film transparency were evaluated over time.

<Anti-fogging property>
◎: No water droplets ○: Some water droplets △: Small water droplets are conspicuous ×: Full surface fogging <Film bleed>
◎: No bleed ×: Many bleed <Transparency of film>
◎: The bottom of the aquarium is clearly visible through the film. ×: The film is cloudy and the bottom of the aquarium appears hazy.

<Test sample>
Resin 1
Polybutylene terephthalate adipate "Eflex" manufactured by BASF
Resin 2
Polylactic acid "Lacia H-440" manufactured by Mitsui Chemicals, Inc.
Polyhydric alcohol fatty acid ester 1
Sorbitan monopalmitate "Rikemar SP-250" produced by Riken Vitamin, approx. 25% esterification rate
Polyhydric alcohol fatty acid ester 2
Sorbitan 20EO triolate "Rikemar O-852" esterification rate, about 75%, manufactured by Riken Vitamin
Polyhydric alcohol fatty acid ester 3
Diglycerin monostearate "Riquemar S-71-D" produced by Riken Vitamin, approx. 30% esterification rate
Polyhydric alcohol fatty acid ester 4
Diglycerin monooleate “Riquemar O-71-DE” manufactured by Riken Vitamin, approx. 30% esterification rate
Polyhydric alcohol fatty acid ester 5
Decaglycerin dedekarate esterification rate of about 95%,
Production Example 95.4 g of decaglycerin and 400 g of oleic acid were charged into a 500 ml four-necked flask equipped with a water separator, thermometer, nitrogen inlet tube and stirring rod, and the acid value was increased at 230 ° C. while blowing nitrogen without using a catalyst. The esterification reaction was carried out for 20 hours until it became 10 or less. After completion of the reaction, the mixture was cooled to obtain 463 g of a pale yellow liquid.
Polyhydric alcohol fatty acid ester 6
Decaglycerin monolaurate “Poem J-0021” manufactured by Riken Vitamin Co. Esterification rate: approx. 8%
Sulfonate surfactant 1
Sodium alkyl sulfonate "Anstex HT-100" manufactured by Toho Chemical Co., Ltd.
Sulfonate surfactant 2
Sodium dioctylsulfosuccinate "Aerosol OT" manufactured by Wako Pure Chemical Industries

[Examples 1-6, Comparative Examples 1-5, Reference Examples 1-2]
In order to prevent a decrease in molecular weight due to hydrolysis, the resin 1 was subjected to a heat drying treatment at 80 ° C. for 5 hours to remove moisture, and then, for 100 parts by mass of the resin 1, for each of Examples and Comparative Examples, A predetermined amount of the test sample (described in Table 2) was blended, and extruded pellets were prepared at 160 ° C. using a twin screw extruder. Using this pellet, a film having a thickness of 80 μm was prepared by a single screw extruder equipped with a T die, and the following evaluations were performed.

  The evaluation results are shown in Table 3 (high temperature anti-fogging property) and Table 4 (low temperature anti-fogging property).

[Examples 7 to 12, Comparative Examples 6 to 10, Reference Examples 3 to 4]
In order to prevent the molecular weight from being lowered due to hydrolysis, the resin 2 was subjected to a heat drying treatment at 80 ° C. for 5 hours to remove moisture, and then, for 100 parts by mass of the resin 2, for each of Examples and Comparative Examples, Predetermined amounts of test samples (described in Table 5) were blended, and extruded pellets were prepared at 180 ° C. using a twin screw extruder. Using this pellet, a film having a thickness of 80 μm was prepared by a single screw extruder equipped with a T die, and the following evaluations were performed.

  The evaluation results are shown in Table 6 (high temperature anti-fogging property) and Table 7 (low temperature anti-fogging property).

  By forming a film or sheet using the biodegradable polyester resin to which the antifogging agent of the present invention is added, the antifogging property, transparency, and flexibility are stable over a long period of time even at low or high temperatures. Films or sheets suitable for agriculture and food packaging materials can be produced.

Claims (5)

An ester of an alcohol selected from sorbitol, sorbitan, and polyglycerin as an antifogging agent (including dehydrated condensed alcohol and an alkylene oxide adduct of a polyhydric alcohol) and a fatty acid with respect to 100 parts by mass of the biodegradable polyester resin. A biodegradable resin composition comprising 0.1 to 5.0 parts by mass and 0.05 to 2.5 parts by mass of a sulfonate surfactant. The biodegradable polyester resin is a polyester obtained by polycondensing a diol containing at least one of ethylene glycol and 1,4-butanediol with a dicarboxylic acid containing at least one of terephthalic acid and adipic acid. The biodegradable resin composition according to claim 1, wherein: The biodegradable resin composition according to claim 1, wherein the biodegradable polyester resin is a lactic acid-based polyester. The esterification rate is 10 to 90% when the ratio of the hydroxyl group esterified with fatty acid in the hydroxyl group of the polyhydric alcohol is defined as the esterification rate. The biodegradable resin composition described in 1. A film or sheet formed from the biodegradable resin composition according to claim 1.