JP2006022299A - Biodegradable polyester-based resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable polyester-based resin composition that exerts an excellent antistatic property. <P>SOLUTION: The resin composition contains a 0.05-10.0 wt% surface active agent, that is a reaction product of boric acid and a compound obtained by esterifying a polyhydric alcohol such as glycerine, diglycerine, sorbitol, cane sugar etc. by an 8-24C higher fatty acid or is a salt (K, Na, Ca, etc.) of the reaction product, to a biodegradable polyester-based resin such as a polylactic acid resin etc. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a biodegradable polyester resin composition imparted with excellent antistatic properties and the like, and more particularly to a polylactic acid resin composition that is a plant-derived renewable resource.

  Plastics such as polypropylene, polyethylene, and polyvinyl chloride, which are made from petroleum and other fossil resources, are transformed into food packaging films, electrical appliances, industrial materials, etc., and are indispensable for our lives. . However, since such plastics are not biodegradable, they remain semipermanent in nature after they are no longer needed, which has a major impact on the ecosystem and leads to environmental destruction in various ways. This is a well-known fact.

  Under such circumstances, biodegradable polyester resins are attracting attention. Among them, plants that do not have biodegradability and are trying to convert from plastics derived from fossil resources Is a biodegradable resin derived from a plant. Of particular interest in recent years is the polylactic acid-based resin whose production volume is dramatically increasing. The factors that have attracted the attention of polylactic acid-based resins are various factors that use fossil resources as raw materials in the context of a material recycling system that conserves limited fossil resources and thoroughly recycles them. While plastics are greatly out of the circulation system, it is possible to construct a material circulation system that recycles sugar obtained from plants such as corn or potato or polylactic acid synthesized from lactic acid obtained by fermenting them. It is because it is expected as a thing.

  The raw material of polylactic acid resin is synthesized from sugars obtained from cereals such as corn or potato, which are renewable resources, or lactic acid obtained by fermenting them. After being easily hydrolyzed and decomposed by microorganisms, it finally becomes water and carbon dioxide.

  It is also known that resin molded products such as films and sheets made of biodegradable polyester resins such as polylactic acid resins exhibit the same performance as conventional plastics. Among these, polylactic acid-based resins have very high transparency, and can be used for packaging applications that place importance on transparency. In addition, the water vapor permeability is higher than that of conventional OPP or OPS films, and there is an expectation that these films can be substituted.

  However, biodegradable polyester resins that have several advantages and can be used in molded products such as films and sheets are very charged because they have electrical insulating properties unique to resins as well as general resins. There are many problems due to electrification, such as ink repelling at the time of printing, scattering when packing the contents, or dust adhering to the product and deteriorating the appearance.

  As a means for solving charging, Patent Document 1 discloses that an antistatic property is imparted by applying an aqueous coating liquid containing a surfactant to at least one surface of an aliphatic polyester film. Alternatively, Patent Document 2 shows that antistatic properties can be imparted by applying a specific anionic surfactant or a specific nonionic surfactant-containing liquid to a polylactic acid biaxially stretched film.

  However, in general, the coating method increases the number of coating steps after resin molding, resulting in an increase in cost, and there are problems such as slipperiness, poor transparency, or lack of sustainability of the antistatic performance specific to the coating method.

  In addition to the method of applying a surfactant to the surface of a molded product such as a film, there is a kneading method in which a surfactant is added to a resin in advance.

  In the kneading method, since the surfactant is pre-kneaded into the resin, the surfactant will exude to the surface of the molded product after molding (bleed out) and the performance will be manifested, and the surfactant on the surface will be wiped off. However, when the surfactant inside the resin further bleeds out, the effect is restored, and there is an advantage of having a certain degree of sustainability. In this way, the kneading method expresses performance by bleeding out the surfactant from the resin, but the degree of this bleed out depends on the crystallinity of the resin such as crystallinity and crystal orientation, and the resin. It is said that it largely depends on the compatibility with the surfactant.

  Furthermore, the crystallinity of the resin and the compatibility of the surfactant greatly affect the transparency of the resin, and the addition of an inappropriate surfactant is a biodegradable polyester such as a polylactic acid resin characterized by transparency. Reduces the transparency of the resin.

  Patent Document 3 discloses that a polylactic acid resin contains a polyhydric alcohol and a fatty acid ester thereof to provide an antistatic film and sheet. Alternatively, Patent Document 4 discloses that polylactic acid contains a nonionic surfactant made of glycerin fatty acid ester to impart antistatic properties. Furthermore, Patent Document 5 shows that an antistatic property is imparted by incorporating a nonionic surfactant containing a glycerin fatty acid ester into a caprolactone-based resin that is a biodegradable resin.

  As described above, many studies have been made on the kneading method of the nonionic surfactant to the biodegradable resin. However, in reality, the crystallinity unique to the biodegradable polyester resin and the compatibility between the resin and the surfactant are considered. Due to the balance, nonionic surfactants have not been able to provide sufficiently satisfactory antistatic properties, and further improvements have been demanded.

JP-A-10-86307 (page 1-14) Japanese Patent Laid-Open No. 14-12687 (page 1-6) Japanese Patent Laid-Open No. 9-221587 (page 1-9) JP 10-36650 A (page 1-14) Japanese Patent Laid-Open No. 14-60603 (page 1-5)

  The objective of this invention is providing the biodegradable polyester-type resin composition which can exhibit the antistatic property which was excellent also in the kneading system in such a condition.

  As a result of intensive studies to solve the above problems, the present inventors have completed the invention of a biodegradable polyester resin composition having excellent antistatic properties and the like. That is, the present invention is a biodegradable polyester resin composition containing 0.05% by weight to 10.0% by weight of a borate ester surfactant having 8 to 24 carbon atoms in the hydrophobic group. In a preferred embodiment of the present invention, the boric acid ester surfactant having a hydrophobic group having 8 to 24 carbon atoms is a polyhydric alcohol such as glycerin, diglycerin, sorbitol, sucrose or the like having 8 carbon atoms. The biodegradable polyester-based resin composition, which is a surfactant which is a reaction product of a compound esterified with a higher fatty acid of ˜24 and boric acid, or a salt of the reaction product (K, Na, Ca, etc.) is there. The biodegradable polyester resin composition of the present invention is particularly excellent in antistatic properties and exhibits a preferable effect even in a polylactic acid resin. Furthermore, this invention is also resin molded articles, such as a film and a sheet which consist of the said resin composition.

  Surface activity which is a reaction product of a compound obtained by esterifying the polyhydric alcohol of the present invention with a higher fatty acid having 8 to 24 carbon atoms and boric acid, or a salt (K, Na, Ca, etc.) of the reaction product A biodegradable polyester resin containing 0.05 wt% to 10.0 wt% of the agent is transparent and can exhibit excellent antistatic performance.

The present invention will be described in detail below.
The present invention relates to a reaction product of a compound obtained by esterifying a polyhydric alcohol such as glycerin, diglycerin, sorbitol, sucrose with a higher fatty acid having 8 to 24 carbon atoms and boric acid, or a salt of the reaction product ( The present invention relates to a biodegradable polyester-based resin composition having excellent antistatic properties and the like, containing 0.05% by weight to 10.0% by weight of a surfactant such as K · Na · Ca.

Hereinafter, the surfactant according to the present invention is described.
In the present invention, the higher fatty acid that is esterified with the polyhydric alcohol has 8 to 24 carbon atoms, and if the carbon number is in such a range, good antistatic properties can be obtained, and the interface in the resin processing step can be obtained. The working environment is not deteriorated by the smoke of the activator. Furthermore, the higher fatty acid may be a saturated fatty acid or an unsaturated fatty acid, and may have a straight chain or a branched chain. Specifically, caprylic acid, 2-ethylhexanoic acid, capric acid, nonanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, oleic acid, linoleic acid, linolenic acid, docosanoic acid, behenic acid, etc. However, it is not limited to these.

  In the ester compound of a polyhydric alcohol and a higher fatty acid in the present invention, the reaction molar ratio of the fatty acid to the polyhydric alcohol is not particularly limited, but is preferably 1.0 to 2.0 mol.

  The reaction molar ratio of boric acid to the compound obtained by esterifying polyhydric alcohols with higher fatty acids in the present invention is not particularly limited, but is preferably 0.1 to 5.0 mol, more preferably 0.5 to 2.0. The mole is good.

  The polyhydric alcohols in the present invention are glycerin, diglycerin, triglycerin, polyglycerin, arabitol, sorbitol, pentaerythritol, polypentaerythritol, glucose, lactose, monosaccharide, sucrose and / or ethylene oxide, propylene oxide thereof. Examples thereof include, but are not particularly limited to, alkylene oxide adducts such as ethylene glycol, propylene glycol, and butylene glycol.

  The salt of the reaction product of the fatty acid ester of polyhydric alcohols and boric acid in the present invention is an alkali metal salt such as sodium salt, potassium salt, magnesium salt, alkaline earth metal salt, or ammonia, diethanolamine, triethanolamine, etc. The organic amine salts are preferably sodium salts and potassium salts.

  The synthesis of the surfactant in the present invention can be obtained by a known method. For example, 1 mol of stearic acid per 1 mol of glycerin is esterified at 230 ° C. under a basic catalyst to obtain glycerin monostearate, and then 1 mol of boric acid is added at 230 ° C. to 1 mol of the compound. The target product can be obtained by the reaction.

  As the surfactant in the present invention, specifically, a reaction product of glycerol monolaurate and boric acid, a reaction product of glycerol monostearate and boric acid, a reaction product of glycerol monooleate and boric acid, and glycerol dilaurate A reaction product of boric acid, a reaction product of glycerol distearate and boric acid, a reaction product of diglycerol monolaurate and boric acid, a reaction product of diglycerol monostearate and boric acid, and a diglycerol monooleate Reaction product of boric acid, reaction product of diglycerol dilaurate and boric acid, reaction product of diglycerol distearate and boric acid, reaction product of diglycerol trilaurate and boric acid, polyglycerol monolaurate and Reaction product with boric acid, reaction product of polyglycerol dilaurate and boric acid, polyoxyethylene glycerol monolaurate Reactant of boric acid, polyoxypropylene glycerol monolaurate and boric acid, sorbitol monolaurate and boric acid, sorbitol monostearate and boric acid, sorbitol mono Reaction product of oleate and boric acid, reaction product of polyoxyethylene sorbitol monolaurate and boric acid, reaction product of polyoxyethylene sorbitol monostearate and boric acid, reaction of pentaerythritol monolaurate and boric acid , Reaction product of pentaerythritol monostearate and boric acid, reaction product of pentaerythritol dilaurate and boric acid, reaction product of sucrose monolaurate and boric acid, reaction of sucrose monostearate and boric acid Product, reaction product of sucrose monooleate and boric acid, polyethylene glycol monora Reaction product of rate and boric acid, reaction product of polypropylene glycol monolaurate and boric acid, sodium salt of reaction product of glycerol monolaurate and boric acid, sodium salt of reaction product of glycerol monooleate and boric acid , Potassium salt of a reaction product of glycerol distearate and boric acid, sodium salt of a reaction product of diglycerol monolaurate and boric acid, calcium salt of a reaction product of polyglycerol monostearate and boric acid, sorbitol mono Examples include sodium salt of a reaction product of laurate and boric acid, calcium salt of a reaction product of pentaerythritol monostearate and boric acid, but are not limited thereto, and these may be used alone or in 2 More than one species may be used in combination.

  The amount of the surfactant of the present invention added to the biodegradable polyester resin is 0.05 wt% to 10.0 wt%, preferably 0.1 wt% to 5.0 wt%, more preferably Is 0.5 wt% to 2.0 wt%. Although the antistatic property is improved in proportion to the content of the surfactant according to the present invention, the antistatic property is not greatly improved even if the content exceeds 10.0% by weight or more. This will affect the mechanical properties of the resin.

  The antistatic agent of the present invention is preferably dried in advance in order to prevent hydrolysis of the biodegradable polyester resin due to moisture. The water content in the surfactant is preferably 1.0% by weight or less.

Hereinafter, the biodegradable polyester resin of the present invention will be described.
The biodegradable polyester resin used in the present invention is, for example, polylactic acid (polylactic acid obtained by polymerizing L-lactic acid or D-lactic acid, or a mixture thereof, and the monomer unit is composed only of L-lactic acid. Polylactic acid, also including a mixture of polylactic acid consisting only of D-lactic acid), polybutylene succinate, polybutylene succinate adipate, polybutylene succinate terephthalate, polybutylene succinate carbonate, polybutylene adipate terephthalate, polyethylene succinate, Examples thereof include polyethylene succinate adipate, polycaprolactone, and polyglycolic acid resin. These monomer units may be chemically modified, and may be a copolymer of different monomer units. In addition, as a monomer unit, a hydroxycarboxylic acid such as glycolic acid or 3-hydroxybutyric acid, a polyvalent carboxylic acid such as succinic acid or adipic acid, a polysaccharide such as cellulose acetate or ethylcellulose, or a polyhydric alcohol such as ethylene glycol or diethylene glycol Of these, a copolymer of one or more kinds and a mixture of monomer units of the resin may be used. Further, for example, starch-based, chitosan-based, polyvinyl alcohol-based resins and petroleum-based resins may be blended within a range that does not impair the object of the present invention.

  As a method for producing the biodegradable polyester resin used in the present invention, a known method is used. In the case of a polylactic acid-based resin, a known method such as a method of directly dehydrating condensation polymerization of lactic acid or a method of ring-opening polymerization of lactide which is a cyclic dimer of lactic acid is used, but is not limited thereto. .

  The molecular weight of the biodegradable polyester resin used in the present invention is not particularly limited as long as it is an optimum molecular weight under molding processing conditions such as a film, a sheet, and a molded product.

  As long as the object of the present invention is not impaired, known anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants other than the present invention may be used alone or in combination of two or more.

  Various additives such as plasticizers, antioxidants, lubricants, colorants, ultraviolet absorbers, light stabilizers, pigments, inorganic fillers, modifiers, and fillers are added as additional components within the scope of the present invention. can do.

  In heat-treating a biodegradable polyester resin, it is necessary to sufficiently dry the polyester resin in order to suppress hydrolysis due to moisture. Therefore, it is preferable that the resin used in advance is dried for 10 hours at 80 ° C. in a nitrogen atmosphere.

  The method for adding the surfactant of the present invention is performed by a known method. That is, a high-concentration master batch is prepared separately, and this may be mixed in an arbitrary process until a molded product such as a film and a sheet is obtained, or may be mixed in advance with a biodegradable polyester resin powder. .

  The biodegradable polyester resin in the present invention can be molded into a film, a sheet or the like by an extruder, a T-die, inflation or the like. The temperature during extrusion is preferably 180 to 250 ° C. in view of the melt viscosity of the resin.

  Furthermore, antifogging property, lubricity, flexibility, and plasticity can be imparted to the biodegradable polyester resin composition by incorporating the surfactant according to the present invention. Moreover, the molecular weight reduction of the biodegradable polyester resin due to the blending of the surfactant is slight.

  EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to the examples.

<1> Synthesis of Surfactant A A glass autoclave was charged with 1.0 mol of glycerin and 1.0 mol of lauric acid, heated to 220-250 ° C. under a basic catalyst while introducing N ₂ gas, and esterified for 5 hours. Glycerol monolaurate was synthesized. Subsequently, 1.0 mol of boric acid is charged per 1.0 mol of the synthesized glycerin monolaurate, gradually heated and dehydrated to 130 to 135 ° C, and then gradually heated to 230 ° C to obtain the desired glycerin monolaurate. A reaction product of laurate and boric acid was synthesized. The obtained surfactant A is used for evaluation of Examples and Comparative Examples described later.

<2> Synthesis of Surfactants B to E A fatty acid ester of a polyhydric alcohol was synthesized by the same synthesis method as that of Surfactant A using the formulation shown in Table 1, and then boric acid was added to the resultant product. Was reacted. The obtained surfactants B to E are used for evaluation of Examples described later.

<3> Synthesis of Surfactant F The above 1.0 mol of Surfactant A is dissolved in methanol, neutralized with an aqueous NaOH (3.0 mol) solution, and recrystallized and purified to obtain Surfactant F. Obtained. The obtained surfactant F is used for evaluation of Examples described later.

<4> Synthesis of Surfactant G A glass autoclave was charged with 1.0 mol of glycerin and 1.0 mol of lauric acid, heated to 220-250 ° C. under a basic catalyst while introducing N ₂ gas, and esterified for 5 hours. Glycerol monolaurate was synthesized. The obtained surfactant G is used for evaluation of comparative examples described later.

  The surfactants of the present invention of Examples 1 to 10 were added to 100 parts by weight of the biodegradable polyester resin at the contents shown in Table 1, and Laboplast mill and roller mixer (manufactured by Toyo Seiki Seisakusho Co., Ltd.). ), The mixed resin was molded into a sheet having a thickness of 2 mm, a length of 100 mm, and a width of 100 mm using a press. This sheet was allowed to stand for 14 days under constant temperature and humidity conditions of a temperature of 23 ° C. and a relative humidity of 50%, and then the antistatic property and transparency were evaluated. The results are shown in Table 2.

  The biodegradable polyester resin is polylactic acid (Lacia H-100 manufactured by Mitsui Chemicals) in Examples 1 to 8, and polylactic acid / succinate polyester (Bionore 3001: Showa High Polymer Co., Ltd.) in Examples 9 and 10. )) = 70 wt% / 30 wt% blended resin was used.

Comparative example

  The evaluation results of the sheets obtained in the same manner as in Examples are shown in Table 2 as Comparative Examples 1 to 4.

<Evaluation method>
The sheet performance was specifically evaluated by the following method.
(1) Antistatic property According to JIS-K-6911, the surface specific resistance value (super insulation meter P-616 by Kawaguchi Electric Co., Ltd.) of the molded sheet was measured. The smaller the value, the better the antistatic property. The target of Log (surface resistivity Ω / □) is 13 or less.

(2) Transparency The HAZE value of the molded sheet was measured with a HAZE measuring apparatus (manufactured by Tokyo Denshoku Co., Ltd., HAZEMETER TC-HIIIDPK), and evaluated by the difference ΔHAZE from the surfactant-free sheet. The smaller ΔHAZE is, the closer the transparency is to the surfactant-free sheet. The target for ΔHAZE is 10 or less.

Furthermore, the lubricity of the sheets prepared in Examples 1 to 10 and Comparative Examples 1 to 4 was measured according to JIS.
Based on K7125-ISO8295, it was evaluated from Tribogear TYPE HEIDON-14DR (manufactured by HEIDON). The results are shown in Table 3.

As shown in Table 2, the biodegradable polyester resin compositions to which the surfactants according to the present invention shown in Examples 1 to 10 are added can exhibit excellent antistatic performance. In addition, as shown in Table 3, lubricity can be imparted to the surface of a molded article of a biodegradable polyester resin composition such as a sheet.

Claims (5)

A biodegradable polyester-based resin composition containing 0.05% by weight to 10.0% by weight of a borate ester-based surfactant having a hydrophobic group having 8 to 24 carbon atoms. Boric acid ester surfactants having 8 to 24 carbon atoms in the hydrophobic group can esterify polyhydric alcohols such as glycerin, diglycerin, sorbitol, and sucrose with higher fatty acids having 8 to 24 carbon atoms. The biodegradable polyester resin composition according to claim 1, which is a surfactant which is a reaction product of the obtained compound and boric acid or a salt (K, Na, Ca, etc.) of the reaction product. The biodegradable polyester resin composition according to claim 1 or 2, having excellent antistatic properties. The resin composition according to any one of claims 1 to 3, wherein the biodegradable polyester resin is a polylactic acid resin. A resin molded product such as a film or sheet comprising the resin composition according to any one of claims 1 to 4.