JPH04198255A - Thermoplastic resin composition resistant to low-temperature impact - Google Patents

Abstract

PURPOSE:To prepare a thermoplastic resin compsn. giving a molded article excellent in the resistance to low-temp. impact by compounding an arom. polyester resin, a specific rubber-reinforced styrenic graft copolymer resin, and a styrenic copolymer resin. CONSTITUTION:20-80 pts.wt. arom. polyester resin (e.g. a polyethylene terephthalate resin), 20-80 pts.wt. graft copolymer resin obtd. by grafting an arom. vinyl monomer and a vinyl cyanide monomer onto a conjugated diene polymer, and 0-15 pts.wt. copolymer resin comprising 60-80wt.% arom. vinyl monomer, 0-40wt.% vinyl cyanide monomer, and 0-40wt.% other copolymerizable ethylenically unsatd. monomers (the sum being 100wt.%) are compounded to give a thermoplastic resin compsn. resistant to low-temp. impact. The latex used for preparing the graft copolymer has a wt.-average particle diameter of 0.20-1.0mum, a conjugated diene polymer fraction of 0.35-0.80, a wt.-average mol.wt. of acetone-sols. of 150000-450000, and an acetone-insol. content satisfying formulas I and II (wherein X is an amt. of a sample of the latex, Y is an acetone-insol. content in the sample, R is the conjugated diene fraction, and Gr is a grafting ratio).

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a thermoplastic resin composition having excellent low-temperature impact resistance. More specifically, the present invention relates to an aromatic polyester, such as a polybutylene terephthalate resin (hereinafter referred to as PBT) consisting of terephthalic acid and tetramethylene glycol.
Abbreviated as resin. ), and a rubber-reinforced styrenic graft copolymer resin composition, from which a molded article having excellent low-temperature impact resistance can be obtained.

"Prior Art" Aromatic polyester resins are thermoplastic resins that generally have various excellent properties including oxidation resistance and solvent resistance. Among these, PBT resin in particular has excellent oxidation resistance and solvent resistance, so it is used for molded industrial parts, but due to its high crystallinity, it has poor impact resistance, especially low notched impact strength. It has its drawbacks. Furthermore, compared to styrene-based polymers, which are general-purpose resins, they also have drawbacks such as poor heat resistance under high loads and poor dimensional stability due to high mold shrinkage.

Therefore, it has been proposed to improve the impact resistance by creating a resin composition in which a rubbery substance is blended with PBT resin.

For example, ABS#A resin (Japanese Patent Publication No. 51-25261, Japanese Patent Application No. 1.-231202, etc.), ethylene-acrylic ester copolymer or ethylene-vinyl acetate copolymer (Japanese Patent Publication No. 58-45225) Publications) and aromatic polycarbonate resins and acrylic rubbers (Japanese Patent Application Laid-Open No. 1986-
25352) and a PBT resin.

However, even if these rubbery substances are blended, it is currently not possible to obtain a PBT resin composition that has excellent impact resistance at low temperatures.

"Problems to be Solved by the Invention" The present inventors have conducted repeated research to obtain a resin composition with excellent impact resistance at low temperatures using a PBT resin and a rubber-reinforced styrene-based graft copolymer resin composition. As a result, we have arrived at the present invention.The present invention provides a molded article with excellent impact resistance at low temperatures by blending a polyester resin and a graft copolymer resin composition prepared to be compatible with the polyester resin. The present invention aims to provide a resin composition that can be used as a resin composition.

[Summary of the invention]

"Means for Solving the Problems" The gist of the present invention is to provide a low-temperature impact resistant product comprising a predetermined amount of the following components (A), (B), and (C). thermoplastic resin composition.

Component (A): Aromatic polyester resin (A) 20-80
M amount component (B): An aromatic vinyl monomer, a cyanide vinyl monomer, and an ethylenically unsaturated monomer copolymerizable with these, if necessary, in the presence of a latex of a conjugated diene polymer. A graft copolymer resin composition (B) 20 obtained by emulsion polymerization of a polyester and a copolymer by the action of a polymerization initiator and satisfying the following conditions (a), (b), (c), (d) and (e).
~803! Part (a) The conjugated diene polymer in Nilatex has a weight average particle diameter of 0.20-1.0 μm; (b) This graft copolymer resin composition contains emulsion-polymerized grafts. When recovering from the copolymer resin latex, there is a step of adding an alkali metal salt, an alkaline earth metal salt, and/or an acid to the graft copolymer resin latex to coagulate it, and washing the resulting coagulate to a pH of 7.0 or less. (c) The graft copolymer resin composition has a conjugated diene polymer fraction R of 0.35 to 0.80. (d): When this graft copolymer resin composition is subjected to acetone extraction at room temperature, the soluble content has a weight average molecular weight of 150,000 to 150,000.
450,000; (e): The insoluble matter when this graft copolymer resin composition is subjected to acetone extraction at room temperature is an amount that satisfies the following formulas (1) and (2).
Here, the symbols have the following meanings.

Weight of X Niger raft copolymer resin composition sample, Y:X
Among them, the weight of the acetone insoluble portion at room temperature, the conjugated diene polymer fraction in the R niger raft copolymer resin composition, the Gr niger raft ratio %] Component (C): aromatic vinyl monomer component 60 to 80% by weight
, vinyl cyanide monomer component 0 to 40% by weight and ethylenically unsaturated monomer component copolymerizable with these 0 to 40% by weight (however, the total monomer component is 10% by weight)
0% by weight. ) Copolymer resin (C) consisting of
0-15 parts by weight.

[Detailed description of the invention]

Aromatic polyester resin (A)> Aromatic polyester resin (A) to be blended with a specific ABS resin (details described later) to impart low-temperature impact resistance to provide a low-temperature impact-resistant thermoplastic resin composition according to the present invention. A) is basically formed from an aromatic dicarboxylic acid and a glycol.

A typical aromatic dicarboxylic acid is terephthalic acid, but in order to modify the crystallinity of the produced polyester, isophthalic acid, lower aromatic dicarboxylic acids, and non-aromatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid are used. etc. can be used together in small amounts.

On the other hand, typical glycol components include glycols having about 2 to 10 carbon atoms, such as ethylene glycol, tetramethylene glycol, and others.

Therefore, the aromatic polyester resin as component (A) of the present invention includes polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), especially PBT.
It is resin.

Graft copolymer resin composition (B) (part 1)> The graft copolymer resin composition (B) constituting the resin composition according to the present invention is a composition in which a specific monomer is synthesized in the presence of a latex of a conjugated diene polymer. It is obtained by emulsion polymerization of polymers.

Since graft copolymerization is carried out by polymerizing monomers in the presence of a polymer, the total amount of monomers is "branch".
In addition to the ideal graft copolymer, which is bonded to the "backbone" of the polymer, a polymer of the monomer itself is usually formed as a by-product, and the graft copolymerization products vary. It is usually a mixture of polymers. In the present invention, the graft copolymerization product is referred to as "graft copolymer resin composition (B
)”, and this is also why requirement (d) has meaning.

The graft copolymer resin composition (B) in the present invention is specified by requirements related to its production ((a) to (c)) and requirements related to itself ((d) to (e)). There is.

<Production of graft copolymer resin composition (B)><Latex of conjugated diene polymer> (1) Monomer species The conjugated diene polymer targeted in the present invention has a conjugated diene component based on its rubber properties. means a polymer that is indebted to

Conjugated dienes frequently used as conjugated dienes in rubber polymers and preferred in the present invention include 1,3-butadiene, isoprene, 1,3-pentadiene, piperylene and chloroprene, especially 1,3-butadiene and isoprene, among others 1,3-butadiene.

Conjugated diene polymers include homopolymers of these conjugated dienes or copolymers of them with each other, as well as copolymers of these conjugated dienes and ethylenically unsaturated monomers copolymerizable therewith. Good too. Specific examples of such comonomers include aromatic vinyl monomers, vinyl cyanide monomers (for specific examples, please refer to the graft copolymerization section below), C1-C5 alkanol of acrylic acid or methacrylic acid (for example,
n-butyl alcohol, i-butyl alcohol) esters, α-olefins such as isobutylene, diene monomers such as divinylbenzene, (poly)alkylene glycol di(meth)acrylates, and others. Of these, the first two are representative, especially styrene and acrylonitrile. Preferably, the content of conjugated diene units in the copolymer is at least 50% by weight,
It is particularly preferred that the conjugated diene unit is 60% by weight or more. If the content of conjugated diene units is less than 50% by weight, the rubber elasticity will be insufficient and, as a result, the impact resistance of the resulting composition will be reduced.

Therefore, preferred specific examples of the conjugated diene polymer targeted by the present invention are poly-1,3-butadiene, polyisoprene, butadiene-styrene copolymer (so-called 5BR), and butadiene-acrylonitrile copolymer (so-called NB).
R).

The latex of such a conjugated diene polymer contains 50 to 100% by weight of the conjugated diene and 0 to 50% by weight of the above comonomer.
It can be produced by emulsion polymerizing a monomer mixture consisting of the following in an aqueous medium all at once or in stages.

In the present invention, the latex of the conjugated diene polymer (hereinafter sometimes referred to as rubber) must satisfy specific conditions regarding the particle size of the conjugated diene polymer.

(2) Rubber particle size (requirement (a)) The conjugated diene polymer has a weight average particle size in the latex of 0.20 to 1.0 μm, preferably 0.25 to 0.0 μm.
．． It is in the range of 65 μm. If the rubber particle diameter is outside the above range, it is not preferable because impact resistance, which is an important characteristic of the resin composition of the present invention, is reduced.

Such a relatively large particle size latex of the conjugated diene polymer may be obtained by performing a particle size enlargement operation to obtain the desired rubber particle size from a small particle size rubber latex.

Particle size enlargement can be achieved using known methods, such as freezing the latex and then remelting it, temporarily lowering the pH of the latex by adding mineral acids, organic acids, etc. Methods of applying shearing force, etc. (JP-A-54-133588, JP-A-59-202211)
This can be done according to the following. In particular, a method of adding phosphoric acid or acetic anhydride to latex is preferred because the particle size can be easily adjusted.

Although the particle size needs to fall within the above range, the rubber particle size distribution does not need to be so-called monomodal with a single peak in the particle size distribution curve, but may have multiple peaks, for example, two peaks. It may be bimodal. In the case of a bimodal particle size distribution, the weight average rubber particle size of both latexes may fall within the range of 0.20 to 1.0 μm.

<Graft copolymerization> The graft copolymer resin composition (B) in the present invention is prepared by:
It is obtained by emulsion polymerization of aromatic vinyl monomers, vinyl cyanide monomers, and other comonomers if necessary.

(1) Aromatic vinyl monomers, etc. The aromatic vinyl monomers used in the present invention include styrene, and side-chain or (and) nucleus-substituted styrene (substituents include lower alkyl groups, lower alkoxy groups, trifluorocarbons, etc.). methyl group, halogen atom, etc.), such as α-
Methylstyrene, p-methylstyrene, 0-methylstyrene, m-methylstyrene, nuclear halogenated styrene, α
- or β-vinylnaphthalene, etc. These may be used in combination within or between groups.

Vinyl cyanide monoffi used in the present invention includes acrylonitrile and methacrylonitrile.

These may be used in combination.

Comonomers copolymerizable with the above-mentioned aromatic vinyl monomers and vinyl cyanide monomers include esters of acrylic acid or methacrylic acid with alkanols having 1 to 10 carbon atoms, especially methyl Acrylates and methyl methacrylates, diene monomers (but in small amounts with monomers such as those mentioned above), e.g. divinylbenzene, (poly)
Alkylene glycol di(meth)acrylate and others.

Aromatic vinyl monomer (S), vinyl cyanide monomer (A
) and comonomer (C) have a weight ratio (A/(A+S+C)) of 20 to 45% by weight, preferably 25 to 40% by weight.
Preferably, it is in weight percent. The comonomer (C) has a weight ratio ('C/(A+S+C)) of up to 40% by weight,
Moderate amounts can be used, preferably up to 30% by weight.

(2) Other conditions As a polymerization initiator for graft copolymerization, commonly used inorganic radical polymerization initiators such as persulfates, organic peroxides, azo metals, etc. can be used alone. or these radical polymerization initiators and sulfites,
A redox radical polymerization initiator in combination with a reducing agent such as a thiosulfate, a ferrous salt, or a sodium formaldehyde sulfoxylate can be used.

Moreover, graft copolymerization can be performed in the presence of a chain transfer agent.

There are no particular restrictions on the chain transfer agent used in graft copolymerization, but mercapkun compounds such as n-octyl mercaptan, t-dodecyl mercaptan (tDM
), or terpinolene, α-methylstyrene linear dimer, etc. are used.

The polymerization temperature conditions for graft copolymerization are 50 to 85°C1
Preferably, a range of 55 to 75° C1 is appropriate. 50
If the temperature is below 85°C, the polymerization reaction rate will be too low to be practical, while if it exceeds 85°C, a large amount of coagulated matter or deposits will be generated at once, resulting in a decrease in polymerization yield and the quality of the final product. This is not desirable because it causes deterioration.

Other graft copolymerization conditions are not essentially different from those commonly used in the production of ABS resins. The entire amount of the monomer for graft copolymerization may be introduced into the polymerization system at once, or may be introduced in stages.

The polymerization in this step is emulsion polymerization, but if the necessary emulsifier supplied from the conjugated diene polymer latex is insufficient, the same or different emulsifier may be added. It is also possible to vary the temperature during polymerization over time.

<Recovery of graft copolymer resin (requirement (b))> In the graft copolymer resin composition (B) of the present invention, an emulsion of an antioxidant is added to the graft copolymer resin latex produced through the above graft copolymerization reaction. The liquids are mixed and an aqueous solution of alkali metal salt, alkaline earth metal salt and/or acid is added to coagulate the latex. Examples of the antioxidant used here include phenolic antioxidants, phosphite antioxidants, thioester antioxidants, and mixtures thereof. Auxiliary agents that can be used when making emulsions from these antioxidants include alkali metal salts of fatty acids, sulfonic acid surfactants, and nonionic surfactants. You may also add alkalis such as Further, as the coagulant, magnesium sulfate, calcium chloride, potassium chloride, sulfuric acid, hydrochloric acid, acetic acid, etc. are commonly used. The coagulated material of the graft copolymer resin produced in the coagulation step is filtered,
However, in the present invention, the separated coagulated graft copolymer resin is treated with a pH (hydrogen ion index) of 7.
This requires a step of washing with washing water adjusted as follows. By washing with acidic washing water with a pH of 7 or less, various auxiliary agents (polymerization initiators, emulsifiers, coagulants, and It is presumed that these reaction by-products, etc.) are washed away or converted into stable products. In addition, in the resin composition of the present invention, the dispersibility and miscibility can be improved without causing local dispersion defects, etc., and the impact resistance at low 14i can be constantly and stably improved. .

Known acids such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, boric acid, nitric acid, acidic sodium sulfate, carbon dioxide gas, etc. can be used as a pH 3m adjustment agent for obtaining washing water with a pH of 7 or less. When cleaning with acidity, adjust the pH of the cleaning water to 7 or less. Particularly preferably, it is adjusted to a range of 6.5 to 3.0. If it is outside this range, the graft copolymer may be deteriorated or it may be difficult to obtain a cleaning effect.

The coagulated water-containing graft copolymer resin after the above washing step is dehydrated using a known dehydrator, such as a centrifugal dehydrator, and then heated and dried using a known dryer, such as a fluidized fluid dryer or a rotary dryer, to carry out graft copolymerization. A resin composition (B) can be obtained.

<Graft copolymer resin composition (B) (Part 2)> The graft copolymer resin composition (B) of the present invention produced in this way has a conjugated diene polymer fraction, a molecular weight of the resin component, and a graft ratio. It must meet the following requirements.

<Conjugated diene polymer fraction in the composition (requirement (c))> In the present invention, the graft copolymer resin composition (B) contains an aromatic vinyl monomer, etc. in the presence of a conjugated diene polymer latex. As mentioned above, it is obtained by emulsion polymerization. This conjugated diene polymer has a conjugated diene polymer fraction (fit
fraction) R is 0.35 to 0.80, preferably 0.40 to
Must be 0.70. If it is less than 0.35, it will be difficult for the resulting resin composition to exhibit impact resistance, and its effectiveness as an impact resistance improver will be reduced. On the other hand, 0.
If it exceeds 80, graft copolymerization becomes difficult and conjugated diene polymer particles agglomerate, which not only impairs the gloss of the molded product when molding the resulting composition, but also reduces impact resistance.

<Molecular weight of resin component (requirement (d))> In the present invention, the above-mentioned As mentioned above, the graft copolymer resin composition (B) produced by the above method contains its own polymer such as an aromatic vinyl monomer.

In the present invention, this polymer is considered to be soluble in acetone at room temperature, and its molecular weight is 150,000 to 450,000, preferably 220,000 to 450,000.
It is specified to be between 10,000 and 400,000 (details of the measurement method will be described later).

This molecular weight! If it is less than 50,000, it will be difficult to make the resulting graft copolymer resin composition exhibit high impact resistance.
On the other hand, if it exceeds 450,000, moldability and dispersibility of graft rubber particles deteriorate, and the appearance and impact resistance of the molded product deteriorate.

Grafting ratio (requirement (e))> In the present invention, the polymer derived from the resinous polymer-forming monomer, other than the acetone-soluble portion mentioned above, is chemically bonded to the rubbery polymer. The degree of graft bonding is expressed as the graft rate % (G'') using the numerical value defined by the following formula (1), and this graft rate is expressed as the graft copolymer resin composition. In relation to the diene polymer fraction (requirement (c)) in product (B), it is set within the range shown by the following formula (2).

where, The conjugated diene polymer fraction (weight fraction) in

In order to obtain high impact resistance in the graft copolymer resin composition (B) of the present invention, the weight content fraction (R
), the optimal grafting rate % (G
r) exists. If the graft ratio is outside this range, the appearance and impact resistance of the molded product will not be sufficiently developed.

The graft ratio defined in this way can be determined by adjusting the type, amount, and/or addition method of the polymerization initiator, chain transfer agent, and emulsifier during graft copolymerization, or (and) adjusting the polymerization time and temperature. By doing so, the desired value can be obtained.

The basic resin mixture of the composition of the present invention includes 20 to 80 parts by weight of the aromatic polyester resin (A), preferably 30 to 70 parts by weight, and the graft copolymer resin composition (B). ) in a range of 20 to 80 parts by weight, preferably in a range of 30 to 70 parts by weight. The above resin mixture is the base resin composition of the composition of the present invention, and in order to obtain the desired physical properties, preferably the total amount of the aromatic polyester resin (A) and the graft copolymer resin composition (B) is is preferably 100 parts by weight. However, as a blending method, the copolymer resin (C
) It is not necessary to mix and knead only the above resin (A) and the above graft copolymer resin composition (B) in advance, and it is not necessary to mix and knead only the above resin (A) and the above graft copolymer resin composition (B) in advance, and it is not necessary to mix and knead only the above resin (A) and the above graft copolymer resin composition (B). However, if the blending ratio is out of the above range, the physical properties of the resulting resin composition, such as mechanical strength, heat resistance, or processability, will deteriorate.

<Copolymer resin (C)> The copolymer resin (C) that is optionally blended into the composition of the present invention is an aromatic vinyl monomer component of 60 to 80% by weight.
, a thermoplastic resin comprising 0 to 40% by weight of a vinyl cyanide monomer component and 0 to 40% by weight of an ethylenically unsaturated monomer (comonomer) component copolymerizable therewith.

The aromatic vinyl monomer, vinyl cyanide monomer, and copolymerizable comonomer, which are the constituent components of the copolymer resin (C), are the components of the graft copolymer resin composition (B). It has the same meaning as each vinyl monomer exemplified as a component. The proportions of the components constituting the copolymer resin (C) are as described above, and by adopting this range, the moldability and miscibility of the resin composition of the present invention can be improved. If it is outside this range, the properties of the copolymerized resin will change, the miscibility with other resins to be mixed will become poor, and the heat resistance or impact resistance at low temperatures of the target resin composition will be reduced, which is not preferable.

The polymerization method and polymerization conditions for the copolymer resin (C) are, for example, emulsion polymerization method, suspension polymerization method, solution polymerization method, bulk polymerization method, according to the known manufacturing technology of acrylonitrile-styrene copolymer (AS resin). A legal method can be selected as appropriate from batchwise or continuous methods.

In addition, this copolymer resin (C) can be produced simultaneously in the same polymerization system during the polymerization operation of the graft copolymer resin composition (B), or it can be produced by setting a separate polymerization method and polymerization conditions. It can also be manufactured.

<Blending of low temperature impact resistant thermoplastic resin composition> The resin composition according to the present invention contains 20 to 80 parts by weight of the aromatic polyester resin (A) as described above and 20 parts by weight of the graft copolymer resin composition (B). Using a resin mixture of ~80 parts by weight as the base resin composition, copolymer resin (C) 0-15
Parts by weight, preferably in the range of 0 to 10 parts by weight, are weighed and mixed. The mixed compound may be left as a tri-blend, but if it is further subjected to a melt-mixing process that does not involve melt-mixing, the desired physical properties such as heat resistance and low-temperature impact resistance may not be obtained, and processing may be difficult. It is not possible to obtain a thermoplastic resin composition with good properties.

In order to blend and mix and knead the constituent components of the resin composition of the present invention, known mixing and kneading methods may be used.

For example, 1[!] of these resins and copolymers in powder, beads, flakes or pellets. Alternatively, a mixture of 2 m or more can be made into a resin composition using an extruder such as a -screw extruder or a twin-screw extruder, or a kneading machine such as a Banbury mixer-1 pressurized kneader or two rolls. In some cases, one of these copolymers after polymerization may be used.
It is also possible to adopt a method in which the seeds or two or more kinds are mixed in an undried state, precipitated, washed, dried, and kneaded.

As for the order of this mixing and kneading, three types of component resins or copolymers may be mixed and kneaded at the same time, or one or more of the component resins or copolymers may be mixed and kneaded first. A desired resin composition may be obtained by separately kneading one or more kinds of resins and kneading them together afterwards.

In addition, if volatile matter remains in the resin composition, physical properties such as heat resistance may deteriorate, so when mixing and kneading using an extruder, the kneading operation should be performed while forcibly devolatilizing the resin composition. It's good to do it. The resin composition thus obtained is used as it is or after being dried for molding and the like.

The resin composition according to the present invention includes a lubricant, a mold release agent, a coloring agent, an antistatic agent, a flame retardant, an ultraviolet absorber, a light resistance stabilizer, and a heat resistance stabilizer in a type and amount that does not impair the properties of the resin. agent,
Various resin additives such as fillers and nucleating agents can be added in appropriate combinations. As a filler, glass fiber,
Examples include metal fibers, carbon fibers, fibrous reinforcing agents such as potassium titanate whiskers, talc, clay, calcium carbonate, mica, glass flakes, milled fibers, metal flakes, metal powders, etc.
It is also possible to mix and match more than one species.

The resin composition according to the present invention can be produced by injection molding method, extrusion molding method,
By various processing methods such as compression molding, it can be made into molded products such as automobile parts, electrical parts, industrial parts, and sports equipment, and can be used in applications that require excellent heat resistance and impact resistance at low temperatures.

"Effects of the Invention" The present invention has been described above, and has particularly remarkable effects as described below, and its industrial utility value is extremely large.

(1) The resin composition according to the present invention can be produced by blending the aromatic polyester resin (A) and the graft copolymer resin composition (B) adjusted to be compatible with the resin (A). It can be used as a thermoplastic resin material with low-temperature impact resistance that was previously unavailable.

(2) Since the resin composition according to the present invention is formulated with each resin optimized, a molded product with low hygroscopicity and chemical resistance that combines the characteristics of each resin can be created. can get.

(3) The resin composition according to the present invention has each resin optimized and blended, so it can be used for excellent resin molding 71u.
It has workability.

(4) Since the resin composition according to the present invention has excellent miscibility with other materials, for example, by mixing and kneading with glass fiber etc. to form a composite, the resin composition can be reinforced with glass fibers with excellent heat resistance and rigidity. It can be made into a rice grain resin composition.

"Examples" Next, the present invention will be specifically explained based on Examples and Comparative Examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

In the following examples, "parts" represent "parts by weight."

In each of the following Examples and Comparative Examples, the physical properties of the resin composition were measured by the following methods.

(1) Izotsu impact strength Measured according to JIS K7110 (notched).

(2) Tensile strength Measured according to JIS K7113.

(3) Melt flow rate Measured according to JIS K7210 at 220°C and 10 kg, and expressed in grams flowing out over 10 minutes.

(4) Weight average particle size of latex The weight average particle size of latex is E manufactured by Coulter Co., Ltd.
Measured using Nanosizer J.

(5) Weight average molecular weight, graft ratio % (i) A certain amount of N(χ) of the graft copolymer is poured into acetone and left overnight at 23°C. After completely dissolving the W copolymer in an ultrasonic cleaner for 15 minutes, centrifugation was performed at 20,000 rpm for 1 hour using a centrifuge i# machine to obtain a soluble component. After evaporating this to dryness, it is dried overnight at 60"C using a vacuum dryer to obtain sample (A).The weight average molecule (■) is
A sample was prepared and measured using GPC (gel permeation chromatography). The molecular weight was obtained as a value in terms of polystyrene.

(ii) Repeat centrifugation twice using the above method to obtain insoluble matter. This is dried overnight at 60°C using a vacuum dryer to obtain an insoluble component (y). The graft rate % was calculated using the following formula.

Fraction (R) The rubber fraction (R) of the graft copolymer resin composition is calculated from the conjugated diene polymer used and the polymerization rate of graft copolymerization, but for a given graft copolymer resin composition. To know this, the rubber content of the acetone-insoluble matter may be measured by the ozonolysis method or the JR (infrared absorption spectrum) method, and calculations may be made based on that value.

Production Example (1) Production of Graft Copolymer I-Fast Composition (B)-1 Into a 5N reactor equipped with a stirring device, a heating and cooling device, and a device for charging each raw material and auxiliary agent, the number of parts shown in Table 1 was added. Emulsion graft polymerization was carried out by charging the raw materials and auxiliary agents.

First, 100 parts of SBR latex (weight average particle diameter: 0.35 μm) with a solid content concentration of 50% by weight and 67 parts of deionized water are charged into the above reactor, and the temperature is raised to 70°C. During heating at 60°C, 0.3 parts of sodium pyrophosphate dissolved in 10 parts of water, dextrose (Dex) O, 12
5 parts and 0.005 parts of ferrous sulfate. 70°
C, 35 parts of styrene, 15 parts of acrylonitrile, and cumene hydroperoxide (CII
P) 0.25 parts, disproportionated rosinate potassium stone MO, 9
1 part and 13 parts of deionized water are added over 2 hours and 30 minutes.

After the addition was completed, the reaction was continued for another 30 minutes, and then cooled to complete the reaction.

Add anti-eclosion agent 1 to the obtained graft copolymer resin latex
After adding 50% of the mixture, it was added to an aqueous potassium chloride solution heated to 95°C with stirring to solidify.

The coagulated product was washed with washing water adjusted to pH 5.0 with hydrochloric acid, and then dried to obtain a white powdery graft copolymer resin composition CB)-1.

Table 1 shows the graft ratio and weight average molecular weight of the obtained graft copolymer resin composition.

(2) Production of graft copolymer resin composition (B)-2 SBR latex with a particle size of 0.1 μm was enlarged to 0.25 μm and 0.65 μm using acetic anhydride, respectively. The reaction was carried out in the same manner as in Production Example (1), except that these were charged in the numbers shown in Table 1, and the post-treatment step was also carried out under the conditions shown in Table 1.

(3) Production of graft copolymer resin compositions (B)-3 to 11 The reaction was carried out in the same manner as in Production Example (1) except that the production conditions were changed to those shown in Table 1. )
-3 to 11 were obtained. Table 1 shows the analysis results of the obtained graft copolymer resin composition.

(4) Copolymer resin (C) An acrylonitrile/styrene copolymer resin having a weight ratio of styrene/acrylonitrile of 70/30 and a molecular weight of 120,000 was used.

Examples 1 to 8, Comparative Examples 1 to 8 PBT resin (A) (N○VADUR5010, manufactured by Mitsubishi Kasei ■), and a graft copolymer resin composition (B) obtained by the method described in the above production example. Copolymer resin (
Weigh out the components of C) at the mixing ratios (parts) listed in Table 2, mix them in a tumbler, and knead the resulting mixture using a vented twin-screw extruder while removing volatile components. hand,
Pellets of the resin composition were prepared.

Test pieces for measuring physical properties were molded from pellets of this resin composition by injection molding. For the molded test pieces, the tensile strength, the sudden impact strength (measured at 23°C with a notch and -20°C), and the melt flow rate were measured in an absolutely dry state. The results are shown in Table 2.

From Table 2, the following becomes clear.

(1) The resin composition according to the present invention is a graft copolymer resin composition (
B), it has high Izod impact strength even at low temperatures (see Examples 1 to 8).

On the other hand, if a graft copolymer resin composition outside this range is used, not only will the Izot impact strength at low temperatures be low, but also the Izot impact strength at room temperature may be low (see Comparative Examples 1 to 6). ).

(2) Since the resin composition according to the present invention contains appropriate amounts of each resin, the mechanical strength shown in tensile strength, Izot impact strength, and melt flow rate,
Excellent balance between heat resistance and moldability (see Examples 1 to 8).

Furthermore, resin compositions obtained outside the scope of the present invention have the disadvantage of poor balance and poor at least one physical property (see Comparative Examples 1 to 8).

Claims (1)

[Claims] (1) A low-temperature impact-resistant thermoplastic resin composition comprising predetermined amounts of the following components (A), (B), and (C). Component (A): Aromatic polyester resin (A) 20-80
Weight part component (B): In the presence of a latex of a conjugated diene polymer, an aromatic vinyl monomer, a vinyl cyanide monomer, and, if necessary, an ethylenically unsaturated monomer copolymerizable with these. Graft copolymer resin composition (B) 20 obtained by emulsion polymerization by the action of a polymerization initiator and satisfying the following conditions (a), (b), (c), (d) and (e)
~80 parts by weight (a): The conjugated diene polymer in the latex has a weight average particle diameter of 0.20 to 1.0 μm; (b): This graft copolymer resin composition does not allow emulsion polymerization. When recovering from the graft copolymer resin latex, a step of adding an alkali metal salt, an alkaline earth metal salt, and/or an acid to the graft copolymer resin latex to coagulate it, and adjusting the resulting coagulated product to a pH of 7.0 or less. (c) The graft copolymer resin composition has a conjugated diene polymer fraction R of 0.35 to 0.80. (d): When this graft copolymer resin composition is extracted with acetone at room temperature, the soluble content has a weight average molecular weight of 150,000 to 150,000.
450,000, (e): When this graft copolymer resin composition is subjected to acetone extraction at room temperature, the insoluble matter is expressed by the following formulas (1) and (2).
Gr=(Y-X・R/X・R)×100(1)30(1
-R)/R≦Gr≦80(1-R)/R(2) [Here, the symbols have the following meanings. X: Weight of graft copolymer resin composition sample, Y: X
Among them, the weight of the acetone insoluble portion at room temperature, R: conjugated diene polymer fraction in the graft copolymer resin composition, Gr: graft ratio %] Component (C): aromatic vinyl monomer component 60 to 80% by weight
, 0 to 40% by weight of vinyl cyanide monomer component and 0 to 40% of ethylenically unsaturated monomer component copolymerizable therewith.
0 to 15 parts by weight of copolymer resin (C) consisting of % by weight (however, the total monomer component is 100% by weight)