JP2006063199A - Polybutylene terephthalate resin composition and molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition which solves problems comprising the remarkable deterioration of thermal stability and hydrolyzing property on melt molding, caused by compounding polybutylene terephthalate (PBT) resin with polylactic acid, holds the mechanical and thermal properties of PBT resin and is afforded with biodegradability. <P>SOLUTION: This polybutylene terephthalate resin composition comprising (A) 100 pts. wt. of PBT resin and (B) 1 to 99 pts. wt. of a biodegradable polylactic acid-based resin is characterized in that the terminal carboxy group concentration of PBT is ≤40 eq/ton. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polybutylene terephthalate resin composition, and more specifically, a polybutylene terephthalate resin composition having biodegradability, excellent residence heat stability during molding, and excellent hydrolysis resistance, and a molded article thereof About.

  Polybutylene terephthalate resin (hereinafter sometimes abbreviated as PBT) as an engineering plastic is easy to mold, mechanical strength, heat resistance, chemical resistance, other physical and chemical properties, and fragrance retention Therefore, they are widely used as materials for automobile parts, electrical / electronic equipment parts, precision equipment parts, etc., and as films, filaments and the like.

  Thus, plastic materials including PBT increase the amount of dust when discarded after use, and are hardly decomposed in a natural environment. Therefore, even if they are buried, they remain in the ground semipermanently. In addition, the discarded plastics cause problems such as damage to the landscape and destruction of the living environment of the ground and marine life. From the viewpoint of environmental conservation in recent years, there has been a demand for plastic materials that are environmentally friendly, such as volume reduction at the time of disposal, ease of atomization, and biodegradability.

  From the viewpoint of environmental conservation, biodegradable polymers have attracted attention. As resins having biodegradability, polylactic acid and copolymers of polylactic acid and other aliphatic polyesters (hereinafter referred to as polylactic acid-based resins), polyaliphatic polymers. An aliphatic polyester derived from a monohydric alcohol and an aliphatic polyvalent carboxylic acid has been developed. Among these biodegradable resins, in particular, polylactic acid-based resins are excellent in that L-lactic acid, which is a raw material, has been produced in large quantities and at low cost by a fermentation method and has high rigidity. It is expected to expand the field of use due to its characteristics. However, even the most promising polylactic acid has several drawbacks compared to conventional polymers based on petroleum resources. Among these, a large thing is that the high-temperature mechanical properties are poor.

By blending such a biodegradable polymer and another resin, development of a resin material having both characteristics has been attempted. For example, Patent Document 1 discloses a structural material in which a mixture of polyethylene terephthalate and polylactic acid is mixed. In this document, an aliphatic polyester contained in a structural material composed of a mixture of such an aromatic polyester and an aliphatic polyester is decomposed by thermal decomposition or solvolysis to decompose the ester bond portion in the thermoplastic polyester at the same time. Therefore, it is described that a molded article that can be easily disposed of after use is obtained.
However, since it has such characteristics, a resin composition in which an aliphatic polyester is blended with an aromatic polyester is considered to have poor thermal stability during melt molding and difficult to put into practical use as an engineering plastic. It was.
JP-A-8-104797

  The present invention has been made in view of such circumstances, and the object thereof is to solve the problem that the thermal stability and hydrolyzability at the time of melt molding, which are caused by blending polylactic acid with PBT resin, are significantly deteriorated. Another object of the present invention is to provide a resin composition that retains the mechanical and thermal properties of PBT resin and imparts biodegradability.

  In order to solve the above-mentioned problems, intensive studies have been made and it has been found that the problem can be solved by using a PBT resin having a reduced terminal carboxyl concentration, and the present invention has been achieved. That is, the gist of the present invention is a composition containing (A) 100 parts by weight of a polybutylene terephthalate resin and (B) 1 to 99 parts by weight of a polylactic acid-based resin having biodegradability. It exists in the polybutylene terephthalate resin composition characterized by the terminal carboxyl group density | concentration of butylene terephthalate being 40 eq / ton or less, and a molded object consisting thereof.

  The resin composition of the present invention has biodegradability, retains the mechanical and thermal properties of PBT resin, and has improved thermal stability and hydrolyzability during melt molding. By molding, it can be effectively used as environmentally friendly materials for products such as automobile parts, electrical and electronic equipment parts, machine parts, packaging materials, and textiles.

Hereinafter, the present invention will be described in detail.
The (A) polybutylene terephthalate resin used in the present invention is a polyester resin obtained from a raw material mainly composed of terephthalic acid or a derivative thereof and 1,4-butanediol, and the terminal carboxyl concentration is 40 eq / ton. It is as follows. The amount of terminal carboxyl groups of the resin can be determined by dissolving PBT in an organic solvent and titrating with an alkali hydroxide solution. By using PBT having a terminal carboxyl group amount of 40 eq / ton or less, the molding residence heat stability of the resin composition of the present invention can be remarkably enhanced, and the hydrolysis resistance can also be improved. The reason is estimated as follows.
The carboxyl group in the PBT causes transesterification with the polylactic acid resin at the time of melt kneading and molding, and decomposes the PBT and the polylactic acid resin, and at the same time decreases the heat resistance. Furthermore, the carboxyl group in PBT acts as an autocatalyst for the hydrolysis of the ester bond. In particular, when a terminal carboxyl group exceeding 40 eq / ton exists, the hydrolysis starts at an early stage, and the generated carboxyl group becomes an autocatalyst. Thus, hydrolysis proceeds in a chain and the degree of polymerization of the resin rapidly decreases. In the resin composition of the present invention, the use of PBT having a terminal carboxyl concentration of 40 eq / ton or less suppresses early hydrolysis and progress of oxidative degradation even under high temperature and high humidity conditions.

  The (A) polybutylene terephthalate resin used in the present invention preferably has an intrinsic viscosity of 0.5 to 1.5 dl / g, more preferably 0.6 to 1.3 dl / g. More preferably, it is 7 to 1.2 dl / g. (A) If the intrinsic viscosity of polybutylene terephthalate is less than 0.5 dl / g, the mechanical strength of the molded product may be insufficient. When the intrinsic viscosity exceeds 1.5 dl / g, the melt viscosity of the resin composition of the present invention is increased, the fluidity is deteriorated, and the moldability may be deteriorated. In the present invention, the intrinsic viscosity of PBT is a value determined from a solution viscosity measured at 30 ° C. using a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (weight ratio 1/1). .

  Although the manufacturing method of the (A) polybutylene terephthalate of this invention which has the amount of said terminal carboxyl groups is not specifically limited, A terephthalic acid or its derivative (s) and 1, 4- butanediol can be made into a main raw material. . The main raw material means that the terephthalic acid component (meaning a derivative such as terephthalic acid or its methyl ester) accounts for 50 mol% or more of the total dicarboxylic acid component, and the 1,4-butanediol component is 50 mol of the total diol component. It means to occupy more than%. The terephthalic acid component preferably accounts for 80 mol% or more of the total dicarboxylic acid component, and more preferably 95 mol% or more. The 1,4-butanediol component preferably accounts for 80 mol% or more of the total diol component, and more preferably 95 mol% or more. In general, when there are many copolymer components other than the terephthalic acid component and the 1,4-butanediol component, the crystallization temperature decreases, so there is an upper limit for the content of the copolymer component, but random, block, etc. The upper limit also varies depending on the copolymerization method.

  There are no particular limitations on the dicarboxylic acid component other than terephthalic acid or its derivatives. For example, phthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenoxyethanedicarboxylic acid, 4,4′-diphenyl Aromatic dicarboxylic acids such as sulfonedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, malon Examples thereof include aliphatic dicarboxylic acids such as acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid, and lower alkyl esters of these dicarboxylic acids.

  The diol component other than 1,4-butanediol is not particularly limited, and examples thereof include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, polytetramethylene ether glycol, 1,5-pentanediol, neo Aliphatic diols such as pentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4-cyclohexanedi Examples include alicyclic diols such as methylol, aromatic diols such as xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane, and bis (4-hydroxyphenyl) sulfone. Rukoto can.

  The PBT used in the present invention further includes hydroxycarboxylic acids such as glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, p-β-hydroxyethoxybenzoic acid, Monofunctional components such as alkoxycarboxylic acid, stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid, tricarballylic acid, trimellitic acid, trimesic acid, pyromellitic acid, gallic acid, trimethyl Trifunctional or higher polyfunctional components such as methylolethane, trimethylolpropane, glycerol, and pentaerythritol can be used as the copolymerization component.

In order to produce polybutylene terephthalate comprising the above dicarboxylic acid or derivative thereof and diol, any method is employed. For example, a polybutylene terephthalate composed of a terephthalic acid component and a 1,4-butanediol component will be described. A direct polymerization method in which terephthalic acid and 1,4-butanediol are directly esterified, dimethyl terephthalate and main raw materials are used. Any transesterification method may be used.
The polymerization method is roughly divided into a batch method and a continuous method. In addition, the initial esterification reaction or transesterification reaction is performed in a continuous operation, and the subsequent polycondensation is performed in a batch operation. Alternatively, the initial esterification reaction or transesterification reaction may be carried out by a batch operation, and the subsequent polycondensation may be carried out by a continuous operation.

  Among these, the direct polymerization method is preferred from the viewpoints of the availability of raw materials, the ease of treatment of the distillate, the height of raw material basic units, and the improvement effect of the present invention. In addition, from the viewpoint of productivity and stability of product quality and the improvement effect of the present invention, a so-called continuous method is preferred in which raw materials are continuously supplied and the esterification reaction and subsequent polycondensation reaction are continuously performed. .

  An example of a method for producing a PBT having a specific terminal carboxyl group concentration and intrinsic viscosity used in the present invention by a continuous method employing a direct polymerization method is as follows. That is, the dicarboxylic acid component having terephthalic acid as a main component and the diol component having 1,4-butanediol as a main component are mixed in a raw material mixing tank to form a slurry, and in one or a plurality of esterification reaction tanks In the presence of a titanium catalyst, the temperature is usually 180 to 260 ° C., preferably 200 to 245 ° C., more preferably 210 to 235 ° C., and usually 10 to 133 kPa, preferably 13 to 101 kPa, more preferably 60 to 90 kPa. Under the pressure of, usually 0.5 to 10 hours, preferably 1 to 6 hours, and the esterification reaction product is continuously transferred to the polycondensation reaction tank. Or in a plurality of polycondensation reaction tanks in the presence of a polycondensation catalyst, preferably continuously, usually 210-280 ° C, preferably 220-265 ° C. Temperature, usually less than 27 kPa, preferably 20kPa or less, more preferably in the following reduced pressure 13 kPa, under agitation, usually 2 to 10 hours, preferably for polycondensation reaction at 2-5 hours. The polymer obtained by the polycondensation reaction is usually transferred from the bottom of the polycondensation reaction tank to a polymer extraction die and extracted in the form of a strand, and while being cooled with water or after being cooled with water, it is cut with a cutter to form pellets and chips. And so on.

  Alternatively, the PBT having a specific terminal carboxyl group concentration and intrinsic viscosity used in the present invention has a terephthalic acid component and a 1,4-butanediol component having a relatively low molecular weight by melt polycondensation, for example, an intrinsic viscosity of 0 After producing PBT of about .1 to 0.9, it can be produced by subsequent solid phase polycondensation (solid phase polymerization) at a temperature not higher than the melting point of PBT until a desired intrinsic viscosity is obtained. Such a method is effective in terms of terminal carboxyl group reduction, oligomer reduction, color tone improvement, and the like.

  It is preferable to use a titanium catalyst as a catalyst in the esterification reaction (or transesterification reaction) between 1,4-butanediol and terephthalic acid (or dialkyl terephthalate). Specific examples of the titanium catalyst include inorganic titanium compounds such as titanium oxide and titanium tetrachloride, titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate. Among these, tetraalkyl titanate is preferable, and among them, tetrabutyl titanate is preferable. When using a titanium compound as a catalyst, it is preferable that the residual amount as a titanium atom is 10 ppm or more and 90 ppm or less. If it exceeds 90 ppm, the heat shock resistance may be reduced. In addition to titanium, a tin catalyst may be used.

  Further, metals such as magnesium, calcium, antimony, germanium, manganese, zinc, zirconium, cobalt, or compounds thereof, orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, phosphorus compounds such as esters and metal salts thereof, hydroxylation Reaction aids such as sodium and sodium benzoate may be used.

  The polylactic acid-based resin (B) having biodegradability used in the present invention may have any structure as long as it is a polylactic acid-based resin in which biodegradability is recognized, and any of them can be suitably used. it can. In the present invention, “having biodegradability” means that biodegradation is recognized according to ISO 14855 (JIS K6953) “How to determine the degree of aerobic ultimate biodegradation and disintegration under controlled composting conditions”. In this method, it is more preferable to decompose 60% or more within half a year.

  Specific examples of the biodegradable polylactic acid resin (B) include polylactic acid, lactic acid-hydroxycarboxylic acid copolymer, and lactic acid-aliphatic polyhydric alcohol-aliphatic polybasic acid copolymer. And polymer blends such as polylactic acid and a mixture of lactic acid-hydroxycarboxylic acid copolymer and lactic acid-aliphatic polyhydric alcohol-aliphatic polybasic acid copolymer, polymer alloys, and the like.

  As raw materials for the polylactic acid-based resin, lactic acids and hydroxycarboxylic acids, aliphatic polyhydric alcohols, aliphatic polybasic acids and the like are used. Specific examples of the lactic acid include, for example, L-lactic acid, D-lactic acid, DL-lactic acid or a mixture thereof, or lactide which is a cyclic dimer of lactic acid.

  Specific examples of hydroxycarboxylic acids that can be used in combination with lactic acids include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, and 6-hydroxycaproic acid. And a cyclic ester intermediate of hydroxycarboxylic acid, for example, glycolide which is a dimer of glycolic acid and ε-caprolactone which is a cyclic ester of 6-hydroxycaproic acid.

  Specific examples of the aliphatic polyhydric alcohol that can be used in combination with lactic acid include, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, and 1,4-butanediol. 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol, 1,4-benzenedi Methanol etc. are mentioned.

  Specific examples of aliphatic polybasic acids that can be used in combination with lactic acids include, for example, succinic acid, oxalic acid, malonic acid, glutaric acid, adivic acid, vimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecane. Diacid, phenyl succinic acid, 1,4-phenylenediacetic acid and the like can be mentioned, and these can be used alone or in combination of two or more.

Examples of the (B) polylactic acid resin that can be used in the present invention include the following (1) to (4).
(1) Lactic acid homopolymer.
(2) Copolylactic acid produced from 50% by weight or more of lactic acid and 50% by weight or less of hydroxycarboxylic acid other than lactic acid.
(3) Copolylactic acid produced from 50% by weight or more of lactic acid, 50% by weight or less of aliphatic polyhydric alcohol and aliphatic polybasic acid.
(4) Copolylactic acid produced from 50% by weight or more of lactic acid, hydroxycarboxylic acid other than 50% by weight or less, aliphatic polyhydric alcohol and aliphatic polybasic acid.

Here, the copolylactic acid may be a random copolymer, a block copolymer, or a mixture of both. Examples of the copolylactic acid that can be preferably used in the present invention include the following.
(I) A random copolymer formed from 50% by weight or more of lactic acid and 50% by weight or less of caprolactone.
(Ii) A random copolymer formed from 50% by weight or more of lactic acid, 50% by weight or less of 1,4-butanediol and succinic acid.
(Iii) A block copolymer comprising 50% by weight or more of a polylactic acid segment and 50% by weight or less of a polycaprolactone segment.
(Iv) A block copolymer comprising 50% by weight or more of a polylactic acid segment and 50% by weight or less of a polybutylene succinate segment.

  As the (B) polylactic acid resin used in the present invention, a lactic acid homopolymer, a block copolymer having a polylactic acid segment and a polybutylene succinate segment and / or a polycaprolactone segment can be particularly preferably used. The weight average molecular weight (Mw) and the molecular weight distribution of the polylactic acid resin preferably used in the present invention are not particularly limited as long as they can be molded. The molecular weight of the polylactic acid-based resin is not particularly limited as long as it exhibits substantially sufficient mechanical properties, but generally, the weight average molecular weight (Mw) is preferably 10,000 to 500,000, and preferably 30,000 to 400,000 is more preferable, and 50,000 to 300,000 is more preferable. Generally, when the weight average molecular weight (Mw) is less than 10,000, mechanical properties are not sufficient, or conversely, when the molecular weight exceeds 500,000, handling becomes difficult or uneconomical. There is.

The polylactic acid-type resin of these aspects can also be used independently, and can also be used in arbitrary 2 or more types of combination. In the present invention, the method for producing the (B) biodegradable polylactic acid resin is not particularly limited, and specific examples thereof include the following methods.
A method of direct dehydration polycondensation using lactic acid or a mixture of lactic acids and hydroxycarboxylic acids as a raw material (for example, a production method disclosed in JP-A-6-65360).
An indirect polymerization method in which a cyclic dimer (lactide) of lactic acid is melt-polymerized (for example, the production method disclosed in US Pat. No. 2,758,987).
A ring-opening polymerization method in which a cyclic dimer of the above lactic acid or hydroxycarboxylic acid, for example, a cyclic ester intermediate such as lactide, glycolide, or ε-caprolactone is melt-polymerized in the presence of a catalyst (US Patent No. 4,057,537).

  In producing polylactic acid-based resin, aliphatic polyhydric alcohols such as glycerin and trimethylolpropane, aliphatic polybasic acids such as butanetetracarboxylic acid, polyhydric alcohols such as polysaccharides, and the like, It may be partially copolymerized, and the molecular weight may be increased by using a binder (polymer chain extender) such as diisocyanate.

  When producing a polylactic acid resin by directly dehydrating polycondensation of raw materials, lactic acid or lactic acids and hydroxycarboxylic acids as raw materials are preferably azeotropically dehydrated in the presence of an organic solvent, particularly a phenyl ether solvent. Polymerization is carried out by a method of condensing and, particularly preferably, removing water from a solvent distilled off azeotropically to bring the solvent into a substantially anhydrous state, and returning it to the reaction system. A lactic acid resin can be obtained. The content of the lactic acid component in the monomer system when polymerizing polylactic acid is 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, and further preferably 80% by weight or more.

The resin composition containing (A) a terminal carboxyl group concentration of 40 eq / ton or less and (B) a biodegradable polylactic acid resin according to the present invention further contains (C) an organophosphorus heat stabilizer. By doing so, the thermal stability and hydrolysis resistance during retention molding are improved.
Examples of the (C) organophosphorus heat stabilizer used in the present invention include organic phosphate compounds such as octadecyl acid phosphate, organic phosphite compounds such as dialkylpentaerythritol diphosphite, diarylpentaerythritol diphosphite, and tetrakis. And organic phosphonite compounds such as (2,4-di-t-butylphenyl) -4,4′-biphenyldiphosphonite. These organophosphorus compounds may be used alone or in combination of two or more. Among these, an organic phosphate compound is preferable. In particular, a long-chain alkyl acid phosphate compound represented by the following general formula (1) is preferable.

(Wherein R represents an alkyl group having 8 to 30 carbon atoms, and n is 1 or 2).
In the general formula (1), specific examples of the alkyl group having 8 to 30 carbon atoms represented by R include n-octyl, 2-ethylhexyl, isooctyl, nonyl, isononyl, decyl, isodecyl, dodecyl, tridecyl, isotridecyl, Tetradecyl, hexadecyl, octadecyl, eicosyl, triancotyl group and the like can be mentioned. Also, a monoalkyl acid phosphate with n = 1, a dialkyl acid phosphate with n = 2, or a mixture thereof may be used.

  The blending ratio of the components (A), (B), and (C) in the composition of the present invention is 1 to 99 parts by weight of (B) polylactic acid-based resin with respect to 100 parts by weight of (A) polybutylene terephthalate resin. Preferably, it is 5 to 70 parts by weight of (B) per 100 parts by weight of (A). (A) If the amount of (B) polylactic acid resin relative to PBT resin is too small, the biodegradability of the resulting composition is insufficient, while if too much (B) component is present, the mechanical properties of the composition Deteriorates rapidly and is not suitable as a molding material. (C) The amount of the organophosphorus heat stabilizer is 0.001 to 2 parts by weight with respect to 100 parts by weight of the total amount of (A) and (B). When the content of (C) is less than 0.001 part by weight, the effect of improving the heat stability and residence stability of the material is lowered, and when it exceeds 2 parts by weight, other performances are adversely affected. The content of the organic phosphorus compound is preferably 0.01 to 0.6 parts by weight, more preferably 0.05 to 0.4 parts by weight, with respect to 100 parts by weight of the total of (A) and (B). is there.

  In addition to the components (A), (B), and (C), the resin composition of the present invention can be used in various known additives such as paraffin wax and polyethylene as long as the properties of the composition are not impaired. Mold release agents such as wax, stearic acid and esters thereof, silicone oil; stabilizers such as hindered phenols, phosphites, and sulfur-containing ester compounds; crystallization accelerators; ultraviolet absorbers or weather resistance imparting agents; Flame retardants and flame retardant aids; inorganic fillers such as glass fibers; may contain dyes, pigments, foaming agents, antistatic agents, etc., and various types such as nylon 6, nylon 66, nylon 12, nylon MXD6 Nylon, various nylon elastomers, liquid crystal polymers, polycarbonate resins, polystyrene, ABS, AS, MS and other styrenic resins, various acrylic resins, Olefin resins such as reethylene, polypropylene, ethylene-propylene copolymer, fluorine resins such as polytetrafluoroethylene, ionomer resins, and elastomers such as isobutylene-isoprene rubber, styrene-butadiene rubber, styrene-butadiene rubber-styrene Further, it may contain a thermosetting resin such as ethylene-propylene rubber, acrylic elastomer, phenoxy resin, phenol resin, melamine resin, silicone resin, epoxy resin.

  The method for producing the resin composition of the present invention is not particularly limited, and the above components (A), (B), and (C) if necessary, and various additive components used as necessary are blended. It can be obtained by melt-kneading. Blending is performed by a commonly used method such as a ribbon blender, a Henschel mixer, a drum blender, or the like. Various extruders, Brabender plastographs, lab plast mills, kneaders, Banbury mixers, etc. are used for melt kneading. The heating temperature at the time of melt kneading is usually 230 to 280 ° C. In order to suppress decomposition during kneading, it is preferable to use the heat stabilizer. Each component including an additional component can be supplied to the kneader in a lump or can be supplied sequentially. In addition, two or more kinds of components selected from each component, including additional components, can be mixed in advance. By adding a fibrous reinforcing filler such as glass fiber after the resin is melted from the middle of the extruder, it can avoid crushing and exhibit high characteristics.

  The resin composition of the present invention can be produced by various known molding methods such as injection molding, hollow molding, extrusion molding, compression molding, calendar molding, rotational molding, etc., in the electrical / electronic equipment field, automobile field, machine field, medical field. Fields, packaging materials, molded articles such as fibers can be obtained. In particular, injection molding is preferably applied because of its good fluidity. In the injection molding, the resin temperature is preferably controlled to 240 to 280 ° C. Moreover, it is suitable also for shaping | molding of the film etc. by extrusion molding.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples.
The materials used in the following examples are as follows.
* PBT-1: Polybutylene terephthalate resin obtained in Production Example 1, terminal carboxyl group concentration 23 eq / t, intrinsic viscosity 1.10 dl / g.
* PBT-2: Polybutylene terephthalate resin obtained in Production Example 2, terminal carboxyl group concentration 45 eq / t, intrinsic viscosity 1.10 dl / g.

* Polylactic acid: manufactured by Mitsui Chemicals, trade name “Lacia, H-100”, MFR at 190 ° C. and 2.16 kg; 7 g / 10 min.

* Organic phosphorus stabilizer-1: Octadecyl acid phosphate, manufactured by Asahi Denka Kogyo Co., Ltd., trade name “AX-71”
* Organic phosphorus stabilizer-2: bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, manufactured by Asahi Denka Kogyo Co., Ltd., trade name “ADK STAB PEP36”

Production Example 1
Both raw materials were supplied to a slurry preparation tank at a ratio of 1.8 mol of 1,4-butanediol with respect to 1.0 mol of terephthalic acid, and 2,976 parts by weight of slurry prepared by mixing with a stirrer (9 terephthalic acid 9 0.06 mol part, and 1,4-butanediol 16.31 mol part) were continuously transferred by a gear pump to the first esterification reaction tank adjusted to a temperature of 230 ° C. and a pressure of 101 kPa, and tetrabutyl titanate 1. 00 parts by weight was supplied, and the esterification reaction was conducted with stirring for 2 hours to obtain an oligomer.
This oligomer was transferred to a second esterification reaction vessel adjusted to a temperature of 240 ° C. and a pressure of 101 kPa, and the esterification reaction was further advanced with stirring for 1 hour.
The oligomer was transferred from the second esterification reaction tank to the first polycondensation reaction tank adjusted to a temperature of 250 ° C. and a pressure of 6.67 kPa, and subjected to a polycondensation reaction with stirring for 2 hours to obtain a prepolymer. It was.
The prepolymer was transferred to a second double condensation reaction tank adjusted to a temperature of 250 ° C. and a pressure of 133 Pa, and the polycondensation reaction was further advanced with stirring for 6 hours to obtain a polymer. The polymer was extracted from the second double condensation tank, transferred to a die, drawn into a strand, and cut with a pelletizer to obtain a beret-like polybutylene terephthalate resin.
The resulting polybutylene terephthalate resin terminal carboxyl group concentration was 23 eq / ton, and the intrinsic viscosity was 1.10 dl / g.
The terminal carboxyl group concentration was determined by dissolving 0.5 g of resin in 25 ml of benzyl alcohol and titrating with 0.01 mol / l benzyl alcohol solution of sodium hydroxide. Intrinsic viscosity was measured by the method described above.

Production Example 2
Both raw materials were supplied to a slurry preparation tank at a ratio of 1.8 mol of 1,4-butanediol with respect to 1.0 mol of terephthalic acid, and 2,976 parts by weight of slurry prepared by mixing with a stirrer (9 terephthalic acid 9 1.06 mole part, and 1,4-butanediol (16.31 mole part) were continuously transferred by a gear pump to the first esterification reaction tank adjusted to a temperature of 250 ° C. and a pressure of 101 kPa, and tetrabutyl titanate 1. 00 parts by weight was supplied, and the esterification reaction was conducted with stirring for 1 hour to obtain an oligomer.
The oligomer was transferred from the first esterification reaction tank to a second esterification reaction tank adjusted to a temperature of 260 ° C. and a pressure of 101 kPa, and the esterification reaction was further advanced with stirring at a residence time of 0.5 hour. The oligomer is transferred from the second esterification reaction tank to the first polycondensation reaction tank adjusted to a temperature of 270 ° C. and a pressure of 6.67 kPa, and subjected to a polycondensation reaction with stirring for 1 hour to obtain a prepolymer. It was.
From the first polycondensation reaction tank, the prepolymer is transferred to a second double condensation reaction tank adjusted to a temperature of 270 ° C. and a pressure of 133 Pa, and the polycondensation reaction is further advanced with stirring for a residence time of 3 hours. Obtained. The polymer was extracted from the second double condensation tank, transferred to a die, drawn into a strand, and cut with a pelletizer to obtain a beret-like polybutylene terephthalate resin.
The resulting polybutylene terephthalate resin had a terminal carboxyl group content of 45 eq / ton and an intrinsic viscosity of 1.10 dl / g.
[Examples 1 to 5, Comparative Examples 1 to 4]

The above polybutylene terephthalate, polylactic acid, and organophosphorous stabilizer were dry blended at the blending ratios shown in Table 1, and a hopper of a twin-screw extruder (manufactured by Nippon Steel Works, TEX30HSST, L / D = 42). And extruded under conditions of a discharge rate of 20 kg / h, a screw rotation speed of 150 rpm, and a barrel temperature of 260 ° C. to obtain PBT resin composition pellets. Using the injection pellet machine (model SG-75, manufactured by Sumitomo Heavy Industries, Ltd.), the obtained pellet was cylinder temperature 280 ° C., mold temperature 80 ° C., filling time 2 seconds, pressure holding time 15 seconds, cooling time. Tensile test pieces for measuring ISO mechanical properties were molded under a condition of 15 seconds and tested by the following method. Moreover, it evaluated according to the following biodegradability test. The results are also shown in Table-1.
[Performance evaluation method of resin composition]

* Tensile test: Measured according to ISO 527.
* Still thermal stability test: Under the above molding conditions, a test piece for measuring ISO mechanical properties was molded in the same manner with a cooling time of 20 minutes. In this case, the mold is cooled, but the resin in the cylinder stays at 280 ° C. for 20 minutes. Using this test piece, the tensile strength was measured according to ISO527. This strength was compared with the strength of a tensile test piece molded from a resin that had a cooling time of 15 seconds and hardly remained, and the strength retention during retention molding was determined.
* Hydrolysis resistance: ISO tensile test pieces were wet-heat treated for 50 hours at 121 kPa, saturated steam at 203 kPa, and the tensile strength before and after treatment was measured according to ISO 527. Asked.
Strength retention (%) = (Tensile strength after treatment / Tensile strength before treatment) × 100

* Biodegradability test: A film having a thickness of 0.30 to 0.37 mm was prepared from the polyester resin composition obtained in the examples or comparative examples by a tabletop hot press method, and this was cut into 2 cm × 2 cm and tested. Created a piece. After the test piece was buried in the soil for 5 months, the decomposition state was observed visually. As a result, if a plurality of worm-eating holes were observed, it was determined that biodegradability was observed (indicated by ○), and if no holes were observed, it was determined that there was no biodegradability (indicated by ×).

As apparent from Table 1, the composition of Comparative Example 3 containing only PBT resin does not exhibit biodegradability, but Examples 1 to 5 and Comparative Examples 1, 2 and 4 in which polylactic acid is blended with PBT resin. Any of these compositions is biodegradable.
Compared to the compositions of Examples 1 and 2 using a PBT resin having a terminal carboxyl group concentration of 23 eq / t, those of Comparative Examples 1 and 2 having the same composition except that a PBT resin having a terminal carbosil concentration of 40 eq / t was used. The composition has greatly reduced tensile strength, retention molding stability, and hydrolysis resistance.
In the compositions of the examples, especially by adding a phosphorus-based heat stabilizer, the tensile strength, the retention molding stability and the hydrolysis resistance are improved, and the machine is almost the same as the composition of Comparative Example 3 using only the PBT resin. Thus, a composition having both physical and thermal properties and biodegradability can be obtained.
From Comparative Example 4, it can be seen that when the blending amount of polylactic acid exceeds the specified range of the present invention, the mechanical properties are rapidly deteriorated, and the molding residence stability and hydrolysis resistance are lowered.

  According to the present invention, it is possible to obtain a PBT resin composition that has biodegradability and has improved thermal stability and hydrolyzability during melt molding, and considers environmental conservation by molding the resin composition. It can be effectively used for products such as automobile parts, electrical and electronic parts, machine parts, packaging materials and textiles.

Claims (4)

  (A) A composition containing 100 parts by weight of a polybutylene terephthalate resin and (B) 1 to 99 parts by weight of a biodegradable polylactic acid resin, wherein the terminal carboxyl group concentration of the (A) polybutylene terephthalate is A polybutylene terephthalate resin composition characterized by being 40 eq / ton or less.   The polybutylene terephthalate resin composition according to claim 1, further comprising (C) an organophosphorus heat stabilizer.   3. The polybutylene terephthalate resin composition according to claim 2, wherein the organophosphorus heat stabilizer (C) is a long-chain alkyl acid phosphate.   The molded object which consists of a polybutylene terephthalate resin composition in any one of Claims 1-3.