JPH07207132A - Polyester resin composition - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a polyester resin composition which is particularly excellent in low-temperature impact strength and has good extrusion stability and a molded article appearance. [Structure] (A) Thermoplastic polyester resin 60 to 99
A vinyl monomer containing at least an epoxy group-containing vinyl monomer was graft-polymerized to a polyorganosiloxane compound rubber comprising (B) a polyorganosiloxane rubber and a polyalkyl (meth) acrylate rubber (B). Then, a resin composition containing 40 to 1 part by weight of a polyorganosiloxane-based graft copolymer obtained by graft-polymerizing a vinyl-based monomer having no epoxy group at the final stage.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyester having improved mechanical strength such as strength and rigidity, impact resistance, especially impact resistance at low temperature, and excellent surface appearance of molded articles. It relates to a resin composition.

[0002]

2. Description of the Related Art Many proposals have hitherto been made as a method for improving the impact resistance of a thermoplastic polyester resin. However, in addition to the thermoplastic polyester resin previously proposed by the present inventors, a polyorganosiloxane-based composite rubber is used. The method of blending a polyorganosiloxane-based graft copolymer obtained by graft-polymerizing a vinyl-based monomer containing glycidyl methacrylate (JP-A-5-5055) has a high impact resistance improving effect even at low temperatures. It is an excellent method to obtain.

[0003]

However, in the above-mentioned method, when a polyorganosiloxane-based graft copolymer in which glycidyl methacrylate is grafted at the final stage of graft polymerization is used, the amount of fine particles during melt-kneading with the thermoplastic polyester resin is very small. However, there is a problem in that the surface appearance of the obtained molded product is deteriorated due to the formation of the gel.

[0004]

In view of the above situation, the present inventors have improved the impact resistance of a thermoplastic polyester resin over a wide temperature range and have a molded product having a good surface appearance. As a result of earnest study to obtain things,
The inventors have found that the above-mentioned problems can be solved by blending a thermoplastic polyester resin with a polyorganosiloxane-based graft copolymer having a specific graft structure, and arrived at the present invention. That is, the present invention comprises (A) 60 to 99 parts by weight of a thermoplastic polyester resin, and (B)
After graft-polymerizing a vinyl-based monomer containing at least an epoxy-group-containing vinyl-based monomer onto a polyorganosiloxane-based composite rubber composed of a polyorganosiloxane rubber and a polyalkyl (meth) acrylate rubber, an epoxy group is added to the final stage. Polyorganosiloxane-based graft copolymer 4 obtained by graft-polymerizing a vinyl-based monomer not containing
A polyester resin composition comprising 0 to 1 part by weight as an essential component.

The thermoplastic polyester resin (A) used in the present invention is (a) an aromatic dicarboxylic acid,
Polyester obtained by polycondensation with dihydric phenol, lower aliphatic diol or alicyclic diol, (b) aromatic polyester comprising aromatic hydroxycarboxylic acid, or (c) above (a) and (b) The main component is a copolyester having both constitutional units.

The aromatic dicarboxylic acid used in the present invention is represented by the following formula (I).

[0007]

[Chemical 1]

Here, the substituted phenylene group means a phenylene group substituted with 1 to 4 substituents, and examples of the substituent of the phenylene group include chlorine, bromine, methyl group and the like. Specific examples of such aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, diphenyl-m, m'-dicarboxylic acid, diphenyl-p, p '.
-Dicarboxylic acid, diphenylmethane-m, m'-dicarboxylic acid, diphenylmethane-p, p'-dicarboxylic acid,
Examples thereof include benzophenone-4,4′-dicarboxylic acid and naphthalenecarboxylic acid. These may be used alone or in combination of two or more. Further, a small amount of an aliphatic dicarboxylic acid such as adipic acid or sebacic acid may be used in combination within a range that does not substantially reduce the physical properties of the polyester in practical use.

As the dihydric phenol used in the present invention, for example, hydroquinone, resorcin, dihydroxynaphthalene, biphenyldiol, 1,8-dihydroxyanthraquinone and the like and compounds represented by the following formula (II) can be used.

[0010]

[Chemical 2]

Specific examples of the dihydric phenol represented by the above formula (II) include 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy. Phenyl ether, 4,4'-dihydroxydiphenyl sulfide,
4,4'-dihydroxyphenyl ketone, 4,4'-dihydroxyphenyl methane, 1,1'-bis (4-hydroxyphenyl) butane, 1,1'-bis (4-hydroxyphenyl) -2,2,2 -Trichloroethane etc. can be mentioned.

The lower aliphatic diol used in the present invention is an alkylene diol having 2 to 6 carbon atoms, and specific examples thereof include ethylene glycol, propylene glycol, 1,
4-butanediol, 1,5-pentanediol, 1,
6-hexanediol etc. can be mentioned.

Examples of the alicyclic diol include cyclohexanediol and cyclohexanedimethanol.

These dihydric phenols, lower aliphatic diols and alicyclic diols may be used alone,
You may use the said 2 or more types of compound in mixture.

Examples of the aromatic hydroxycarboxylic acid used in the present invention include hydroxycarboxylic acids represented by the following formula (III).

[0016]

[Chemical 3]

Specific examples of such an aromatic hydroxycarboxylic acid include m-hydroxybenzoic acid, p-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, and 2-hydroxybenzoic acid.
(4'-hydroxyphenyl) -2- (4'-carboxyphenyl) propane, 4-hydroxyphenyl-4-
Examples thereof include carboxyphenyl ether, and these may be used alone or in combination of two or more.

Among these polyesters, polyesters selected from polyethylene terephthalate, polybutylene terephthalate and poly 1,4-cyclohexylene dimethylene terephthalate can be mentioned as preferable examples.

Next, the (B) polyorganosiloxane-based graft copolymer used in the present invention means a composite rubber composed of a polyorganosiloxane rubber and a polyalkyl (meth) acrylate rubber, and at least an epoxy group-containing vinyl-based monomer. It is obtained by graft-polymerizing a vinyl-based monomer containing a polymer, and then graft-polymerizing a vinyl-based monomer not containing an epoxy group in the final stage of the graft polymerization. The polyorganosiloxane rubber used here What is obtained as a fine particle can be used for this as an organosiloxane, the polyorganosiloxane rubber cross-linking agent, and the polyorganosiloxane rubber graft crossing agent are polymerized.

Examples of the organosiloxane used for preparing the polyorganosiloxane rubber include various cyclic compounds having three or more membered rings, and those having 3 to 6 membered rings are preferably used. Specific examples of such organosiloxanes include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, and octamethylcyclophenylsiloxane. Examples thereof include phenylcyclotetrasiloxane, and these may be used alone or in combination of two or more kinds.

The cross-linking agent for polyorganosiloxane means a silane compound having 3 or 4 lower alkoxy groups,
That is, it is trialkoxyalkylsilane, trialkoxyphenylsilane or tetraalkoxysilane, and specific examples thereof include trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. Among these, tetraalkoxysilane is preferable, and tetraethoxysilane is particularly preferable.

The graft crossing agent for polyorganosiloxane rubber is a poly (meth) acrylate rubber which does not react when preparing a polyorganosiloxane rubber and is subsequently used in the presence of a polyorganosiloxane rubber for preparing a composite rubber. The siloxane having a functional group which reacts during the polymerization or the graft polymerization, and specific examples thereof include compounds capable of forming units represented by the following formulas (IV) to (VII).

[0023]

[Chemical 4]

[0024]

[Chemical 5]

[0025]

[Chemical 6]

[0026]

[Chemical 7]

As the unit capable of forming the unit of the formula (IV),
Methacryloyloxyalkyl mono-, di- or trialkoxysilanes are preferred, and specific examples thereof include β-methacryloyloxyethyldimethoxymethylsilane, γ
-Methacryloyloxypropylmethoxydimethylsilane, γ-methacryloyloxypropyldimethoxymethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyldiethoxymethylsilane, γ-methacryloyloxypropylethoxydiethylsilane, δ-methacryloyloxybutyl Examples thereof include diethoxymethylsilane, and among these, γ-methacryloyloxypropyldimethoxymethylsilane and γ-methacryloyloxypropyltrimethoxysilane are more preferable.

Examples of those capable of forming the unit of formula (V) include vinyltrimethoxysilane, vinylmethyldimethoxysilane and the like, and examples of those capable of forming the unit of formula (VI) include 4 -Vinylphenyldimethoxymethylsilane, 4-vinylphenyltrimethoxysilane, and the like, and examples of those capable of forming the unit of formula (VII) include γ-mercaptopropyldimethoxymethylsilane and γ-mercaptopropyltrimethoxy. Examples thereof include silane and γ-mercaptopropyldiethoxyethylsilane.

Among the compounds represented by these formulas, the formula (I
The (meth) acryloyloxy (alkyl) silane that can form the unit V) forms an effective graft chain due to the high grafting efficiency during graft polymerization, and therefore it is possible to obtain a product having excellent impact resistance. , Is preferably used in the present invention.

The amount of the component derived from the cyclic organosiloxane in the polyorganosiloxane rubber is 60% by weight or more,
It is preferably 70% by weight, the amount of the crosslinking agent for polyorganosiloxane rubber is 0.1 to 30% by weight, and the amount of the graft crossing agent for polyorganosiloxane rubber is 0.
10 to 10% by weight.

Polyorganosiloxane rubbers are described, for example, in US Pat. Nos. 2,891,920 and 3,294,725.
Although it can be obtained as a latex using the method described in the specification etc., a mixed solution of an organosiloxane and a crosslinking agent for a polyorganosiloxane rubber and, if desired, a graft crossing agent for a polyorganosiloxane rubber is treated with an alkylbenzene sulfonic acid, It is preferably produced by shear mixing with water using a homogenizer or the like in the presence of a sulfonic acid emulsifier such as an alkyl sulfonic acid.
As the sulfonic acid-based emulsifier, alkylbenzene sulfonic acid is preferably used because it acts as an emulsifier of organosiloxane and at the same time acts as a polymerization initiator. At this time, it is preferable to use a metal salt of alkylbenzene sulfonic acid, a metal salt of alkyl sulfonic acid, or the like together, because it is effective in maintaining a stable emulsion state of the polymer during the graft polymerization.

The termination of the polymerization can be carried out by adding an alkaline aqueous solution such as sodium hydroxide, potassium hydroxide or sodium carbonate.

A composite rubber composed of a polyorganosiloxane rubber and a polyalkyl (meth) acrylate rubber is obtained by adding the above-mentioned polyorganosiloxane rubber latex to a crosslinker for alkyl (meth) acrylate, polyalkyl (meth) acrylate rubber and polyalkyl (meth) acrylate rubber. It is obtained by adding a graft crossing agent for a (meth) acrylate rubber, impregnating the polyorganosiloxane rubber with these components, and then polymerizing.

The alkyl (meth) acrylate used for preparing the composite rubber has an alkyl group having a carbon number of 1 to
A linear or branched acrylate of 8 and an alkyl (meth) acrylate having 6 to 12 carbon atoms in the alkyl group can be shown. Specific examples thereof include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, 2-methylbutyl acrylate, 3-methylbutyl acrylate, 3-pentyl acrylate. , Hexyl acrylate, heptyl acrylate, 2-heptyl acrylate, octyl acrylate, 2-octyl acrylate, 2-ethylhexyl acrylate, hexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate and the like. n
-Butyl acrylate is preferred.

As the crosslinking agent for polyalkyl (meth) acrylate rubber, (meth) acrylate having two or more polymerizable unsaturated bonds is used, and specific examples thereof include ethylene glycol dimethacrylate, propylene glycol dimethacrylate, Examples thereof include 1,3-butylene glycol dimethacrylate and 1,4-butylene glycol dimethacrylate.

The graft crossing agent for a polyalkyl (meth) acrylate rubber is polymerized during polymerization of the polyalkyl (meth) acrylate rubber and incorporated into the rubber, but at least a part of the polymerizable unsaturated group remains without being polymerized. However, it is a monomer having two or more polymerizable unsaturated bonds capable of being graft-bonded by reacting the remaining unsaturated groups during the subsequent graft polymerization. Specific examples of such a graft crossing agent include allyl methacrylate and triethyl methacrylate. Allyl cyanurate,
Examples include triallyl isocyanurate.
Allyl methacrylate is a polyalkyl (meth) acrylate rubber during polymerization, part of which reacts with both of the two polymerizable unsaturated groups to form a crosslinked structure, and the rest reacts with only one of the unsaturated groups, The other unsaturated bond remains after the polyalkyl (meth) acrylate rubber polymerization, and during the subsequent graft polymerization, the remaining unsaturated bond reacts to form a graft bond. Also has the effect of working.

These polyalkyl (meth) acrylate rubber cross-linking agents and polyalkyl (meth) acrylate rubber graft crossing agents may each be a single component or a combination of two or more components. May be. When acrylic methacrylate is used, this alone may serve as the crosslinking agent and the graft crossing agent.

The amounts of the cross-linking agent for polyalkyl (meth) acrylate rubber and the graft crossing agent for polyalkyl (meth) acrylate rubber used are the polyalkyl (meth) acrylate.
Acrylic methacrylate rubber component 0.1 to 10% by weight
Is. When allyl methacrylate alone serves as a crosslinking agent and a graft crossing agent, it may be used in an amount of 0.2 to 20% by weight in the polyalkyl (meth) acrylate rubber component.

The composite rubber is prepared by emulsion-polymerizing an organosiloxane and then adding an aqueous solution of an alkali such as sodium hydroxide, potassium hydroxide or sodium carbonate to neutralize the polyorganosiloxane rubber latex to obtain the above-mentioned alkyl. After adding a (meth) acrylate, a cross-linking agent for polyalkyl (meth) acrylate rubber and a graft crossing agent for polyalkyl (meth) acrylate rubber and impregnating these into polyorganosiloxane rubber particles, usual radical polymerization initiation Polymerization may be carried out by acting an agent. This makes it possible to obtain a composite rubber in which the polyorganosiloxane rubber and the polyalkyl (meth) acrylate rubber are intertwined with each other to such an extent that they cannot be substantially separated from each other. The composite rubber preferably has a gel content of 80% or more when measured by extraction with toluene at 90 ° C. for 4 hours.

As the composite rubber, the main skeleton of the polyorganosiloxane rubber component has a repeating unit of dimethylsiloxane, and the main skeleton of the polyalkyl (meth) acrylate rubber component has a repeating unit derived from n-butyl acrylate. Are preferred.

The ratio of the polyorganosiloxane rubber component to the polyalkyl (meth) acrylate rubber component in the composite rubber is preferably 1 to 99% by weight for the former and 99 to 1% by weight for the latter. If the proportion of the polyorganosiloxane rubber component exceeds 99% by weight, the surface appearance of the molded product from the composition deteriorates, and if the proportion of the polyalkyl (meth) acrylate rubber component exceeds 99% by weight, impact resistance, especially at low temperature There is a tendency for the impact resistance to be insufficiently expressed.

The polyorganosiloxane-based copolymer (B) used in the present invention contains at least an epoxy group-containing vinyl monomer in a composite rubber composed of a polyorganosiloxane rubber and a polyalkyl (meth) acrylate rubber. It is obtained by graft-polymerizing a vinyl-based monomer and then graft-polymerizing a vinyl-based monomer not containing an epoxy group as the final stage. The vinyl-based monomer containing at least the epoxy-group-containing vinyl-based monomer as used herein may be composed of only the epoxy-group-containing vinyl-based monomer, or may be copolymerized with the epoxy-group-containing vinyl-based monomer. It means that it may be a mixture of other possible vinyl monomers and epoxy group-containing vinyl monomers.

As the epoxy group-containing vinyl monomer,
Glycidyl methacrylate, glycidyl acrylate,
Examples thereof include vinyl glycidyl ether, allyl glycidyl ether, hydroxyalkyl (meth) acrylate glycidyl ether, polyalkylene glycol (meth) acrylate glycidyl ether, and glycidyl itaconade. Among these, glycidyl methacrylate is more preferable.

Examples of other vinyl monomers copolymerizable with the vinyl monomer containing an epoxy group include methacrylic acid esters such as methyl methacrylate and 2-ethylhexyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate and the like. Acrylic acid ester of styrene, halogen-substituted styrene, α-methylstyrene,
Aromatic alkenyl compounds such as vinyltoluene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; organic acids having a carbon-carbon unsaturated double bond such as acrylic acid and methacrylic acid. The above is used in combination with the epoxy group-containing vinyl monomer. Of these vinyl monomers, styrene, methyl methacrylate and butyl acrylate are preferably used.

Examples of the vinyl-based monomer having no epoxy group to be graft-polymerized at the final stage of graft polymerization include methacrylic acid esters such as methyl methacrylate and 2-ethylhexyl methacrylate; acrylic acid such as methyl acrylate, ethyl acrylate and butyl acrylate. Esters; aromatic alkenyl compounds such as styrene, halogen-substituted styrene, α-methylstyrene and vinyltoluene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; carbon atoms such as acrylic acid and methacrylic acid
Examples thereof include organic acids having a carbon unsaturated double bond, and these are used alone or as a mixture of two or more kinds.

When the polyorganosiloxane-based graft copolymer having a component derived from an epoxy group-containing vinyl-based monomer and the thermoplastic polyester resin are melt-mixed, preferably by melt-kneading using an extruder or the like, the graft copolymer The epoxy group in the polymer and the terminal functional group of the thermoplastic polyester resin react with each other to form a part of them bound to each other,
This acts as a compatibilizing agent for the thermoplastic polyester resin and the polyorganosiloxane-based graft copolymer to improve the compatibility between the two. As a result, the composition of the present invention exhibits high impact strength. However, when the epoxy group is present in the outermost layer of the graft copolymer, a microgel is formed by the reaction between the epoxy groups, and the surface appearance of the molded product is deteriorated. The present invention uses the outermost layer of a polyorganosiloxane-based graft copolymer as a component not containing an epoxy group, avoids an unfavorable reaction between epoxy groups, and improves the generation efficiency of a polymer that acts as a compatibilizer. Is.

The amount of the epoxy group-containing vinyl monomer is 1 to 3 of the total amount of the polyorganosiloxane graft copolymer.
It is preferably 0% by weight, more preferably 2 to 20% by weight. If the proportion in the graft copolymer is less than 1% by weight, the impact strength will be insufficiently expressed, and if it is used in excess of 30% by weight, no further effect will be exhibited.

The amount of the epoxy group-free vinyl monomer grafted in the final stage is preferably 1 to 10% by weight based on the total weight of the polyorganosiloxane graft copolymer. If it is less than 1% by weight, it is not enough to avoid the reaction between epoxy groups, while if it exceeds 10% by weight, the reaction between the epoxy group and the terminal functional group of the polyester resin is hindered.

The total amount of graft monomers grafted on the composite rubber is preferably 2 to 50% by weight based on the total amount of polyorganosiloxane-based graft copolymer.

The polyorganosiloxane-based graft copolymer used in the present invention preferably has an average particle size in the range of 0.08 to 0.5 μm, and when the average particle size is smaller than 0.08 μm. It becomes difficult to sufficiently improve the impact strength, while if it exceeds 0.5 μm, the surface appearance of the obtained resin composition may be deteriorated.

The average particle size of the polyorganosiloxane-based graft copolymer was measured using a quasi-elastic light scattering method (measuring device, MALVERN SYSTEM 4600, measuring temperature 25 ° C., scattering angle 90 °). A sample solution diluted with can be measured.

In the graft polymerization, a component corresponding to a branch of the graft copolymer (here, a component derived from two or more kinds of monomers including an epoxy group-containing vinyl monomer) is a trunk component (here, a polyorganosiloxane rubber). A so-called free polymer obtained by polymerizing only a branch component without grafting to a polyalkyl (meth) acrylate composite rubber) is also obtained as a by-product and is obtained as a mixture of a graft copolymer and a free polymer. In the above, both are collectively referred to as a graft copolymer.

The blending ratio of the (A) thermoplastic polyester resin and the (B) polyorganosiloxane-based graft copolymer used in the present invention is such that the thermoplastic polyester resin 60 to 99 is used in view of the impact strength of the resulting composition. 40 parts by weight of polyorganosiloxane-based graft copolymer
It is necessary to set the amount to 1 part by weight (total of 100 parts by weight of both), and preferably 20 to 3 parts by weight. When the amount of the polyorganosiloxane-based graft copolymer used is less than 1 part by weight, the effect of improving the impact resistance of the thermoplastic polyester resin is poor, and when it exceeds 40 parts by weight, the strength and rigidity of the molded product from the composition, It is not preferable because the heat resistance tends to be impaired.

The composition of the present invention may further contain a filler in order to further improve the heat resistance and mechanical strength of the composition. As such a filler, those having various shapes such as a fibrous shape, a particulate shape, and a powder shape can be used.

Specific examples of the filler include, for example, glass fiber, carbon fiber, potassium titanate, asbestos, silicon carbide, ceramic fiber, metal fiber, silicon nitride, aramid fiber, barium sulfate, calcium sulfate, calcium silicate,
Calcium carbonate, magnesium carbonate, antimony trioxide, zinc oxide, titanium oxide, magnesium oxide, iron oxide, molybdenum disulfide, mica, talc, kaolin, pyrophyllite, bentonite, sericite, zeolite, wollastonite and other clays , Ferrite,
Examples thereof include graphite, gypsum, glass beads, glass balloons and quartz.

When a filler is used, the resin component 100
It is preferable to use 10 to 300 parts by weight of the filler with respect to parts by weight. If it is less than 10 parts by weight, the effect of improving heat resistance and mechanical strength is small, and if it exceeds 300 parts by weight, the melt fluidity of the composition tends to be poor and the appearance of the molded article tends to be impaired, such being undesirable.

In the resin composition of the present invention, if necessary,
Further, plasticity, flame retardant, pigment and the like may be added.

The composition of the present invention can be obtained by melt-mixing at least a thermoplastic polyester resin and a polyorganosiloxane-based graft copolymer, and the preparation method thereof is not particularly limited, but the polyorganosiloxane-based graft copolymer is prepared. Polyorganosiloxane-based graft copolymer dry powder and thermoplastic polyester resin obtained by adding the copolymer latex to an aqueous solution of a metal salt such as calcium chloride or magnesium sulfate, salting out, coagulating, separating and collecting, and drying. Further, it is preferable to add a filler if necessary, melt-knead in an extruder, and pelletize. The pellets thus obtained can be molded at a wide range of temperatures and can be molded using a normal injection molding machine.

[0059]

EXAMPLES The present invention will be described in detail below with reference to Examples and Comparative Examples, in which "parts" represent "parts by weight". The physical properties in Examples and Comparative Examples were measured by the following methods under absolutely dry conditions.

(1) Average particle size: quasi-elastic light scattering method (MA
LVERN SYSTEM 4600, measurement temperature 25
The sample was prepared by diluting the latex with water at a temperature of 90 ° C. and a scattering angle of 90 °).

(2) Stability during extrusion: No strand break (1 hour) ○ Strand break (1 hour) ×

(3) Izod impact strength: ASTM. D
256 methods (1/8 ", notched)

(4) Surface appearance: visually determined. No surface spots ○ Surface spots ×

Reference Example 1 Preparation of Polyorganosiloxane Graft Copolymer (S-1) 2 parts of tetraethoxysilane, 0.5 part of γ-methacryloyloxypropyldimethoxymethylsilane and 97.5 parts of octamethylcyclotetrasiloxane. Were mixed to obtain 100 parts of a siloxane mixture.

Sodium dodecylbenzene sulfonate and dodecylbenzene sulfonic acid were each added to 0.67
200 parts of dissolved distilled water was added to 100 parts of the mixed siloxane
In addition to the parts, after pre-stirring at 10,000 rpm with a homomixer, 200 kg / c with a homogenizer
It was emulsified at a pressure of m ² to obtain an organosiloxane latex. This latex was placed in a separable flask equipped with a condenser and a stirring blade, heated at 80 ° C. for 5 hours while stirring and mixing, and then allowed to stand at 20 ° C., 4
After 8 hours, the pH of this latex was neutralized to 7.2 with an aqueous sodium hydroxide solution to complete the polymerization and obtain a polyorganosiloxane rubber latex-1 (hereinafter, this latex is referred to as PDMS-1). . The conversion to polyorganosiloxane rubber is 89.1%,
The average particle size of the polyorganosiloxane rubber is 0.19μ
It was m.

140 parts of this PDMS-1 was taken, placed in a separable flask equipped with a stirrer, 700 parts of distilled water was added, and after nitrogen substitution, the temperature was raised to 50 ° C. and n-butyl acrylate 313. A mixture of 6 parts, 6.4 parts allyl methacrylate and 1.2 parts tert-butyl hydroperoxide was added. Then, a mixed solution of 0.008 parts of ferrous sulfate, 0.024 parts of ethylenediaminetetraacetic acid disodium salt, 1.2 parts of sodium formaldehyde sulfoxylate and 40 parts of distilled water was added thereto to carry out radical polymerization to give an internal temperature of 70 The temperature was kept at 2 ° C. for 2 hours to obtain a composite rubber latex (hereinafter, this latex is referred to as composite rubber latex-1).

285 parts of this composite rubber latex-1 was sampled, and 10 parts of glycidyl methacrylate and ter
A mixture of 0.024 parts of t-butyl hydroxyperoxide was added dropwise over 30 minutes, and the mixture was kept at an internal temperature of 60 ° C. for 1 hour. Then, a mixture of 5 parts of methyl methacrylate and 0.012 parts of tert-butyl hydroxyperoxide was added to 30 parts of the mixture. Graft polymerization was carried out on the composite rubber by dropping over a period of time and maintaining the internal temperature at 60 ° C. for 2 hours. Polymerization rate of glycidyl methacrylate and methyl methacrylate is 98.5%
And the average particle size of the graft polymer was 0.24 μm. This latex was added at 40 ° C. in an aqueous 5% calcium chloride solution such that the ratio of the latex and the aqueous solution was 1: 2, and then the temperature was raised to 90 ° C. to coagulate. After cooling this, the solid content was separated by filtration and dried overnight at 80 ° C. to obtain a powdery polyorganosiloxane-based graft copolymer (hereinafter referred to as S-1).

Reference Example 2 A polyorganosiloxane-based graft copolymer was prepared in the same manner as in Reference Example 1 except that 5 parts of glycidyl methacrylate was used instead of 5 parts of methyl methacrylate as the final graft monomer in the production process of S-1. A dry powder of the polymer (S-2) was obtained. The polymerization rate of glycidyl methacrylate was 98.2%, and the average particle size of the latex was 0.24 μm.

Example 1 and Comparative Example 1 Polybutylene terephthalate (manufactured by Mitsubishi Rayon Co., Ltd., Toughpet (registered trademark) N-1000) was used as the thermoplastic polyester resin, and the polyorganosiloxane-based resin obtained in Reference Examples 1 and 2 was used. The graft copolymers S-1 and S-2 were blended in the proportions shown in Table 1, and the twin-screw extruder (Toshiba Machine Co., Ltd.) was used.
Manufactured by TEM-35B) with a cylinder temperature of 240 ° C.
It was melt-mixed with and pelletized. At this time, the stability at the time of extrusion was evaluated by the frequency of strand breakage.

After drying the obtained pellets, a test piece was molded using an injection molding machine (Promat injection molding machine manufactured by Sumitomo Heavy Industries, Ltd.) at a cylinder temperature of 240 ° C. and a mold temperature of 80 ° C. The evaluation of the sex and the appearance were performed. The results are shown in Table 1.

[0071]

[Table 1]

[0072]

The polyester resin composition of the present invention having the constitution as described above is excellent in impact resistance, particularly impact strength at low temperature, and is excellent in extrusion stability and appearance of a molded product. It can be used very effectively in a wide range of applications.

Claims (1)

[Claims] 1. A thermoplastic polyester resin (A) 60-
99 parts by weight, and (B) a polyorganosiloxane-based composite rubber composed of a polyorganosiloxane rubber and a polyalkyl (meth) acrylate rubber is graft-polymerized with a vinyl-based monomer containing at least an epoxy group-containing vinyl-based monomer. Then, a polyester resin composition comprising 40 to 1 part by weight of a polyorganosiloxane-based graft copolymer obtained by graft-polymerizing a vinyl-based monomer having no epoxy group in the final stage.