JP2005154594A - Biodegradable resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly safe compound considerably improving processability and moldability of a polyester resin having biodegradability at the molding, and giving little load on the environment. <P>SOLUTION: The biodegradable polyester resin composition contains a processability-improving agent. The processability-improving agent is an ester compound of (A) an ester formed out of an aliphatic compound having a hydroxy group and a polybasic acid, or an ester formed out of the aliphatic compound having the hydroxy group, the polybasic acid and a 6-22C fatty acid, and having at least one free carboxy group per molecule of the ester remaining therein. The content of the ester compound based on 100 pts. by mass of the biodegradable polyester resin is 0.05-5 pts. by mass. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a biodegradable resin composition having excellent processability during molding.

  Sheets and films molded from plastics 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 in everyday life. ing.

  However, while these plastic products have the characteristic of durability, when they are used as waste after their mission of use, their good durability is inferior in degradability in nature, and they are It has negative aspects that cause environmental destruction, such as impact.

  Biodegradable plastics are attracting attention in order to overcome such drawbacks of plastics. Biodegradable plastics are decomposed into low-molecular compounds in a very short time by the action of enzymes produced by microorganisms that inhabit the environment, and finally decomposed into inorganic substances such as water and carbon dioxide.

  The recent increase in awareness of environmental issues has led to the legalization of plastic product recycling, 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 can be used for agricultural materials used in the environment (for example, sheets or films used for root vegetable growing houses) and materials used in the food packaging field where collection is difficult (for example, food packaging films or sheets). Etc.) is expected.

  These biodegradable plastics can be broadly divided into microbial production systems, natural product utilization systems, and chemical synthesis systems. Currently, biodegradable plastics that have begun to be put into practical use include aliphatic polyesters, modified polyvinyl alcohol, or starch modified products. And these blends.

Among these biodegradable plastics, aliphatic polyesters include polybutylene succinate, polyhydroxybutyrate, and polylactic acid.
For example, polylactic acid is a crystalline thermoplastic polymer that has the same tensile strength as polyethylene and the same transparency as polyethylene terephthalate. It is used for pharmaceutical sutures and is highly safe. Burning calories are as small as about 1/3 of polyethylene, polypropylene, etc., rarely damage the incinerator, and no harmful gas is generated. It is also promising in that it uses recyclable plant resources as raw materials, unlike petroleum-based plastics. Due to these advantages, research and development of manufacturing methods and applied applications has become active in recent years, and diversification of applications and associated increase in production volume are expected in the future.

  However, the biodegradable polyester resin has such advantages, but it is inferior in molding processability, causing problems that the resin adheres to the die surface during processing, and that the surface of the molded film, sheet, or molded product may fall. To do.

As a method for improving such a molding problem, a method of preventing the resin from sticking to the die surface by adding a lubricant to the resin in advance is generally used. An example in which a metal soap, an aliphatic hydrocarbon, a higher aliphatic acid, a fatty acid amide, a fatty acid ester, or the like is blended as a lubricant with a biodegradable polyester resin is disclosed (for example, see Patent Document 1). Moreover, although the example which mix | blends a liquid fatty acid metal salt or fatty acid amide as a lubricant with the lactic acid-type biodegradable resin is disclosed (for example, refer patent document 2), the metal soap and aliphatic described in them are disclosed. When hydrocarbons, higher aliphatic acids, and fatty acid amides are used as lubricants, the addition of an amount that provides sufficient moldability inhibits the transparency of the resin, causing the molded product to become cloudy or reduce thermal stability. In addition, there are many disclosures of blending fatty acid esters with biodegradable resins (see, for example, Patent Documents 3, 4, and 5), but there is no specific description in the examples, and fatty acids into biodegradable polyesters. The effect of ester as a lubricant was not clear.
JP 06-080872 A Japanese Patent Laid-Open No. 11-140291 JP 2002-322355 A JP 2002-294048 JP-A-11-279271

  An object of the present invention is to provide a compound that significantly improves processability and moldability during molding of a biodegradable polyester resin, and has high safety and low environmental impact.

  As a result of intensive studies in view of the above problems, the inventors of the present invention are esters composed of an aliphatic compound having a hydroxyl group in the molecule and a polybasic acid, and at least one free carboxylic acid per molecule of the ester is present. The present invention has been completed by finding that the above problems can be achieved by blending the remaining ester into a biodegradable polyester resin as a processability improver.

That is, the present invention has the following configuration.
1. In the biodegradable polyester resin composition containing the processability improver, the processability improver is an ester compound represented by A below, and the ester compound is added to 0.05 parts by weight per 100 parts by mass of the biodegradable polyester resin. A biodegradable polyester resin composition comprising ˜5 parts by mass.

  A: an aliphatic compound having a hydroxyl group and a polybasic acid, or an ester of an aliphatic compound having a hydroxyl group, a polybasic acid, and a fatty acid having 6 to 22 carbon atoms, and at least one free carboxyl group per molecule of the ester Remaining ester compound.

2. 2. The biodegradable polyester resin composition as described in 1 above, wherein the polybasic acid in the ester compound is an aliphatic dicarboxylic acid or a tricarboxylic acid.

3. In the ester compound, the aliphatic compound having a hydroxyl group in the molecule is a higher aliphatic alcohol, a polyhydric alcohol having 2 to 6 carbon atoms, and / or a polycondensate thereof. 2. The biodegradable polyester resin composition according to 2.

  In the present invention, by adding the ester compound of the present invention as a processability improver, it becomes possible to supply a biodegradable polyester resin product having good processability during processing and being environmentally friendly.

The present invention will be described in more detail.
As the biodegradable polyester resin in the present invention, a hydroxycarboxylic acid known as a biodegradable resin or a polymer obtained by polymerizing a diol and a dicarboxylic acid can be used without any limitation. Any of the hydroxycarboxylic acid, diol, and dicarboxylic acid used may be a copolymer using a plurality of types.

  Examples of the hydroxycarboxylic acid in the present invention include lactic acid, glycolic acid, ε-caprolactone, and 3-hydroxybutanoic acid. Examples of the diol include ethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, bisphenol A, and the like. Examples of the dicarboxylic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, fumaric acid, isophthalic acid, and terephthalic acid.

  Polymerizing polyhydric carboxylic acids such as malic acid, tartaric acid and citric acid and polyhydric alcohols such as glycerin, diglycerin, polyglycerin, trimethylolpropane, pentaerythritol and dipentaerythritol within a range not impairing the performance of the present invention. Also good. Further, isocyanate compounds, epoxy compounds, aziridine compounds, oxazoline compounds, polyvalent metal compounds, polyfunctional phosphate esters, phosphite esters, and the like may be used as chain extenders.

  Examples of the polybasic acid constituting the ester compound used in the present invention include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, Examples thereof include aliphatic dicarboxylic acids such as citraconic acid, itaconic acid, malic acid and tartaric acid, and aliphatic tricarboxylic acids such as tricarparic acid and citric acid.

  Examples of the aliphatic compound having a hydroxyl group in the molecule constituting the ester compound used in the present invention include higher aliphatic alcohols such as lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, aralkyl alcohol, and behenyl alcohol, or ethylene glycol. 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, trimethylolpropane, erythritol , Pentaerythritol, dipentaerythritol, xylitol, mannitol, sorbitol, sorbitan and other polyhydric alcohols or polycondensates thereof.

  Examples of the fatty acid having 6 to 22 carbon atoms constituting the ester compound used in the present invention include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, And erucic acid.

  In the present invention, these raw materials can be reacted alone or as a mixture of two or more, or the obtained products can be used alone or as a mixture of two or more in addition to a biodegradable polyester resin. It is.

  The partial ester of a polyhydric alcohol which is an aliphatic compound having a hydroxyl group in the molecule of the present invention and a higher fatty acid, and the ester of an aliphatic compound having a hydroxyl group in the molecule and a polybasic acid are known using the above raw materials. It can adjust using the reaction method of these.

  In the ester compound of the present invention, it is necessary that at least one carboxyl group derived from the polybasic acid remains in the reaction product, and all the carboxyl groups of the polybasic acid molecule are reacted as an ester. The improvement effect to the biodegradable polyester resin which is the object of the present invention is not expressed. Therefore, in the case of a dibasic acid, it is preferable to use an equimolar reaction with an aliphatic compound having a hydroxyl group in the molecule. In the case of a tribasic acid, a fatty acid having a hydroxyl group in the molecule with respect to 1 mol of the tribasic acid. The group compound preferably has 1 to 2 moles of reaction.

  In this invention, the compounding quantity with respect to resin of the ester compound as a workability improvement agent is 0.05 to 5 weight% with respect to resin, More preferably, the inside of the range of 0.1 to 5 weight% is preferable. When it falls below this range, the performance is insufficient, and when it exceeds, the transparency and mechanical properties of the molded product are deteriorated and the performance is lowered.

  In the present invention, a lubricant, a release agent, and other additives may be used in combination so as not to impair the effects of the present invention. However, those having good safety and biodegradability such as higher fatty acid, higher fatty acid metal soap, aliphatic amide, and montanic acid ester are preferable.

  The biodegradable polyester resin composition in the present invention can be molded using a normal plastic molding method without any particular limitation, but is preferably molded using an extruder. The molding temperature is preferably 120 to 220 ° C. When polymer blending is performed, it is preferable to use a twin screw extruder. The resin composition melted in the extruder can be formed into a sheet, a film or a molded product by T-die, inflation or the like.

  In addition, these resins may be used in combination with fillers, heat stabilizers, plasticizers, antioxidants, antistatic agents, slip agents, antifogging agents, and the like. It can be used as long as the effect of the agent is not impaired.

Hereinafter, the present invention will be described in detail with reference to examples, but the embodiment of the present invention is not limited thereto.

<Production example>
Distilled monoglycerides include glycerin monolaurate [Riquemar M-300: manufactured by Riken Vitamin Co., Ltd.], glycerin monostearate [Riquemar S-100: manufactured by Riken Vitamin Co., Ltd.], glycerin monobehenate [Riquemar B-100: manufactured by Riken Vitamin Co., Ltd.] ], 1 mol of distilled monoglyceride and 1 mol of succinic anhydride were charged into a reaction vessel equipped with a stir bar and subjected to esterification reaction at 120 ° C. for 2 hours, whereby glycerin succinate laurate and glycerin succinate stearate Thus, glycerin succinic acid behenate was obtained.

  Moreover, esterification reaction with 1 mol of citric acid was similarly performed using 1 mol of these distilled monoglycerides, and glycerol citrate laurate, glycerol citrate stearate, and glycerol citrate behenate were obtained. Further, stearyl citrate was prepared by the same esterification reaction of 1 mol of citric acid and 2 mol of stearyl alcohol. As the polyethylene wax, “High Wax 200P” manufactured by Mitsui Chemicals, Inc. was used.

<Examples 1-7 and Comparative Examples 1-5>
A predetermined amount of the sample was blended with 100 parts by mass of an aliphatic polyester resin (Bionore # 1001, Showa High Polymer Co., Ltd.), kneaded and extruded with a twin screw extruder, and then pelletized. The obtained pellets were kneaded in a 170 ° C. lab plast mill for 10 minutes. After kneading, the peelability from the rotor part and the peelability from the jacket part were evaluated. The peeled sample was pressed at 170 ° C. and 100 MPa for 3 minutes to prepare a 1 mm thick sheet, and the surface property of the sheet was evaluated. The results are shown in Table 1.

Peelability ○: The sample can be peeled off without sticking to the rotor or jacket
Δ: Sample adheres slightly to the rotor and jacket
×: The sample sticks to the rotor and jacket, and the sample cannot be peeled. Surface property ○: The surface is smooth and glossy
Δ: Surface is slightly rough
×: The surface is rough

<Examples 8 to 14 and Comparative Examples 6 to 10>
A predetermined amount of a sample was blended with 100 parts by mass of a polylactic acid resin (Lacia H-100, manufactured by Mitsui Chemicals), kneaded and extruded with a twin screw extruder, and then pelletized. The obtained pellets were kneaded in a 190 ° C. lab plast mill for 10 minutes. After kneading, the peelability from the rotor part and the peelability from the jacket part were evaluated. The peeled sample was pressed at 190 ° C. and 100 MPa for 3 minutes to prepare a 1 mm thick sheet, and the surface property and transparency of the sheet were evaluated. The results are shown in Table 2.

Peelability ○: The sample can be peeled off without sticking to the rotor or jacket
Δ: Sample adheres slightly to the rotor and jacket
×: The sample sticks to the rotor and jacket, and the sample cannot be peeled. Surface property ○: The surface is smooth and glossy
Δ: Surface is slightly rough
×: The surface is rough Transparency ○: The sheet is transparent
Δ: The sheet is slightly cloudy
×: The sheet is cloudy

Claims (3)

In the biodegradable polyester resin composition containing the processability improver, the processability improver is an ester compound represented by A below, and the ester compound is added to 0.05 parts by weight per 100 parts by mass of the biodegradable polyester resin. A biodegradable polyester resin composition comprising ˜5 parts by mass.
A: an aliphatic compound having a hydroxyl group and a polybasic acid, or an ester of an aliphatic compound having a hydroxyl group, a polybasic acid, and a fatty acid having 6 to 22 carbon atoms, and at least one free carboxyl group per molecule of the ester Remaining ester compound. The biodegradable polyester resin composition according to claim 1, wherein the polybasic acid in the ester compound is an aliphatic dicarboxylic acid or a tricarboxylic acid. The aliphatic compound having a hydroxyl group in the molecule in the ester compound is a higher aliphatic alcohol, a polyhydric alcohol having 2 to 6 carbon atoms, and / or a polycondensate thereof. Or the biodegradable polyester resin composition of 2.