JP2776908B2 - Low temperature impact resistant resin composition - Google Patents

Description

BACKGROUND OF THE INVENTION <Industrial Application Field> 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) comprising terephthalic acid and tetramethylene glycol.
Abbreviated as resin. ), And a resin composition from which a molded article having excellent low-temperature impact resistance comprising a rubber-reinforced styrene-based graft copolymer can be obtained.

<Prior Art> Aromatic polyester resins are thermoplastic resins generally having various excellent properties such as oxidation resistance and solvent resistance. Among them, PBT resin is particularly excellent in oxidation resistance and solvent resistance, so it is used for molded products of industrial parts.However, it has high crystallinity, so it has high impact resistance, especially low notched impact strength. Has disadvantages. It also has the disadvantage that heat resistance under high loads and dimensional stability are inferior to styrene-based polymers which are general-purpose resins.

Therefore, it has been proposed to improve the impact resistance by using a resin composition in which a rubber-like substance is blended with a PBT resin.

For example, ABS resin (JP-B-51-25261), ethylene-acrylate ester copolymer or ethylene-vinyl acetate copolymer (JP-A-58-45225), aromatic polycarbonate resin and acrylic rubber (JP-B-58-45225) Kaisho 58
No. -25352) and a PBT resin.

However, even if these rubber-like substances are blended, a PBT resin composition having excellent impact resistance at low temperatures has not been obtained at present.

<Problems to be Solved by the Invention> The present inventors have conducted studies to obtain a resin composition having excellent low-temperature impact resistance using a PBT resin and a rubber-reinforced styrene-based graft copolymer. The invention has been reached. The present invention seeks to provide a resin composition capable of obtaining a molded article having excellent low-temperature impact resistance by blending a polyester resin and a rubber-reinforced styrene-based graft copolymer prepared so as to be compatible therewith. Is what you do.

[Summary of the Invention]

<Means for Solving the Problems> The low-temperature impact-resistant resin composition according to the present invention comprises 30 to 70% by weight of an aromatic polyester resin (A),
A copolymer component 60 in which the weight ratio of 60% by weight to the aromatic vinyl monomer component / vinyl cyanide monomer is 80 to 60/20 to 40 (however, the total of both monomers is 100) And the rubber component has a rubber average particle size of 0.2 to 40% by weight.
1.0 μm, the graft ratio of the copolymer component grafted to the rubber component is 40 to 80%, and the weight-average molecular weight of the ungrafted copolymer component is 15%.
100 parts by weight of a resin mixture comprising 30 to 70% by weight of a rubber-reinforced styrene-based graft copolymer resin (B) having a molecular weight of not less than 000, 50 to 90% by weight of an aromatic vinyl monomer component, and a vinyl cyanide monomer component 0 to 40% by weight and 0 to 40% by weight of methyl methacrylate component
100% by weight. ) Copolymer resin (C) 0-1
5 parts by weight.

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

(1) The resin composition according to the present invention is prepared by blending a PBT resin (A) and a rubber-reinforced styrene-based graft copolymer resin (B) prepared so as to be compatible with the PBT resin (A). It can be used as a thermoplastic resin material having low-temperature impact resistance that could not be obtained.

(2) Since the resin composition according to the present invention is obtained by optimizing and blending each resin, it is possible to obtain a molded article having the characteristics of each resin and having low moisture absorption and excellent chemical resistance. Can be

(3) The resin composition according to the present invention has excellent resin moldability since each resin is optimized and blended.

(4) Since the resin composition according to the present invention has excellent miscibility with other materials, it is mixed and kneaded with, for example, glass fiber to form a composite, thereby enhancing glass fiber reinforcement having excellent heat resistance and rigidity. Resin composition.

[Specific description of the invention]

<Aromatic Polyester Resin (A)> Aromatic polyester resin (A) to be imparted with low-temperature impact resistance by blending a specific ABS resin (described later in detail) to give a low-temperature impact resistance resin composition according to the present invention.
Is basically formed from an aromatic dicarboxylic acid and a glycol.

As the aromatic dicarboxylic acid, terephthalic acid is typical, but in order to modify the crystallinity and the like of the formed polyester, isophthalic acid and other aromatic dicarboxylic acids and non-aromatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and the like are used. Can be used in small amounts.

On the other hand, examples of the glycol component include glycols having about 2 to 10 carbon atoms, such as ethylene glycol, tetramethylene glycol, and the like.

Thus, the aromatic polyester resins as component (A) of the present invention are polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), especially PBT.

<Impact-Improving Material (B)> The rubber-reinforced styrene-based graft copolymer resin (B), which is a compounding component of the resin composition according to the present invention, comprises a rubber component having a glass transition temperature of 0 ° C. or lower and an aromatic component. A graft copolymer resin obtained by graft polymerization of a monomer mixture containing a vinyl monomer component as a main component and containing 60% by weight or more.

As the rubber component, a conjugated diene rubber is preferable, and particularly preferable specific examples include polybutadiene, styrene-butadiene rubber, and acrylonitrile-butadiene rubber.

Specific examples of the aromatic vinyl monomer component which is a copolymerization component for graft polymerization include styrene, α-alkylstyrene such as α-methylstyrene, nucleus-substituted alkylstyrene such as p-methylstyrene, and vinylnaphthalene. No. These may be one kind or a mixture of two or more kinds.

Specific examples of the vinyl cyanide monomer component, which is a copolymer component, include acrylonitrile and methacrylonitrile.

Specific examples of the rubber-reinforced styrene-based graft copolymer resin (B) include acrylonitrile / butadiene / styrene copolymer (ABS resin), methylene methacrylate / butadiene / styrene copolymer (MBS resin), and methyl methacrylate / acrylonitrile・ Butadiene / styrene copolymer (MABS resin), acrylonitrile / acrylic rubber / styrene copolymer (AAS resin), acrylonitrile / EPDM / styrene copolymer (AES resin), acrylonitrile / chlorinated polystyrene / styrene copolymer ( AC
S resin) or a mixture thereof. The rubber-reinforced styrene-based graft copolymer resin (B) has an excellent impact resistance, and is effective as an impact modifier (impact resistance imparting material) by being blended with another resin material.

However, in the resin composition according to the present invention, the rubber-reinforced styrene-based graft copolymer resin (B), which effectively functions as a low-temperature impact modifier, comprises a rubber component.
40 to 60% by weight, 60 to 40% by weight of a copolymer component having an aromatic vinyl monomer component / vinyl cyanide monomer component weight ratio of 80 to 60/20 to 40, and a rubber component Has a rubber average particle diameter of 0.2 to 1.0 μm, and the graft ratio of the aromatic vinyl monomer component / vinyl cyanide monomer component copolymer component grafted to the rubber component is 40 to 80%.
Having a weight average molecular weight of 150,000 or more (preferably 155,000 to 50) of a copolymer component comprising an ungrafted aromatic vinyl monomer component / vinyl cyanide monomer component.
0,000 range). Outside of this range, the effect of improving the low-temperature impact resistance of the resin composition according to the present invention becomes extremely small.

 In the present invention, the average particle system of the graft rubber is 0.05
Coulter Electronics Co., Ltd. (C
oulter Electronics Ltd.) “Nanosizer” (Coult
er Nano-Sizer^TM), The raw material before graft polymerization
Measured in a system in which water latex is dispersed in water at 23 ° C.
It refers to the amount average particle size. About the range of about 0.5 ~ 4μm
Is a Coulter Electronics Co., Ltd.
Tertiary model TAII
Dissolve a small amount of the graft copolymer and add a small amount of thiocyanic acid
The solution to which potassium was added was subjected to weight average particle measurement at 23 ° C.
Refers to the diameter.

In the present invention, the graft ratio refers to a ratio (%) obtained by the following measurement method. First, the rubber-reinforced styrene-based graft copolymer resin (B) was put into acetone and left overnight, and then subjected to an ultrasonic cleaner for 15 minutes to completely dissolve the free copolymer, and then centrifuged. Using
Centrifugation is repeated twice at 20000 rpm for 1 hour to obtain an insoluble content. Next, although the rubber content in the rubber-reinforced styrene-based graft copolymer resin (B) is subtracted from the dried weight of the insoluble matter, it is determined based on the rubber content in the rubber-reinforced styrene-based graft copolymer resin (B). , Ratio (%).

In the present invention, the weight average molecular weight (Mw) is defined as the weight ratio of the ungrafted aromatic vinyl monomer component / vinyl cyanide monomer component in the rubber-reinforced styrene-based graft copolymer resin (B). The weight-average molecular weight of the coalesced component. Specifically, the rubber-reinforced styrene-based graft copolymer resin (B) is put into acetone and left overnight, and then released (grafted) for 15 minutes using an ultrasonic cleaner. Is completely eluted, and then centrifuged at 20,000 rpm for 1 hour using a centrifuge to obtain a soluble component, which is evaporated to dryness. Prepare a solution and use GPC (gel permeation
The molecular weight in terms of styrene measured by chromatography).

This rubber-reinforced styrene-based graft copolymer resin (B)
Is a method in which an aromatic vinyl monomer component is used as a main component in the presence of rubber by a known emulsion polymerization method, bulk polymerization method, solution polymerization method, or the like, and a mixture of the aromatic vinyl monomer component and vinyl cyanide is graft-polymerized by a known method. Can be obtained by

<Optional Component (C)> The copolymer resin (C) to be added to the resin composition of the present invention as required comprises 60 to 90% by weight of an aromatic vinyl monomer component and a vinyl cyanide monomer component. It is a thermoplastic resin comprising 0 to 40% by weight and 0 to 40% by weight of a methyl methacrylate component.

Specific examples of the aromatic vinyl monomer component which is a copolymer component of the copolymer resin (C) include α-alkylstyrene such as styrene and α-methylstyrene, and a nuclear-substituted alkyl such as p-methylstyrene. Styrene, vinyl naphthalene and the like can be mentioned. These may be one kind or a mixture of two or more kinds.

The proportion of the aromatic vinyl monomer component in the copolymer resin (C) is in the range of 50 to 90% by weight, preferably 50 to 80% by weight. If the ratio is out of this range, properties such as heat resistance and miscibility with other resins of the copolymer resin (C) change, and a resin composition having excellent physical properties cannot be produced. Specific examples of the vinyl cyanide monomer component which is a copolymer component of the copolymer resin (C) include acrylonitrile and methacrylonitrile.

The proportion of the vinyl cyanide monomer component in the copolymer resin (C) is in the range of 0 to 40% by weight, preferably 0 to 30% by weight.
% By weight. If it exceeds 30% by weight, the physical properties of the obtained resin are reduced, and the desired resin composition cannot be obtained.

The polymerization method and the polymerization conditions of the copolymer resin (C) are, for example, known acrylonitrile-styrene copolymer (hereinafter, referred to as acrylonitrile-styrene copolymer).
Abbreviated as AS resin. ) According to the production technology, emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, etc.,
It can be appropriately selected from a batch system or a continuous system.

Further, the copolymer resin (C) may be simultaneously produced in the same polymerization system in the polymerization operation of the rubber-reinforced styrene-based graft copolymer resin (B) and / or the copolymer resin (C). It can be produced by separately setting a polymerization method and polymerization conditions.

<Composition and Formation of Composition> The resin composition of the present invention comprises a PBT resin (A) in an amount of 30 to 70% by weight, preferably 40 to 60% by weight, and a rubber-reinforced styrene-based graft copolymer resin (B ) In an amount of from 30 to 70% by weight, preferably from 40 to 60% by weight, in which the copolymer resin (C) is optionally added. However, as a compounding method, it is not necessary to previously mix and knead only the PBT resin (A) and the copolymer resin (B) prior to the compounding of the copolymer resin (C). What is necessary is just to observe the compounding ratio of the resin composition. When the compounding ratio is out of the above range, physical properties such as mechanical strength, heat resistance, and workability of the obtained resin composition are deteriorated.

The resin composition according to the present invention comprises 100 parts by weight of a resin mixture comprising the aromatic polyester resin (A) as described above and a rubber-reinforced styrene-based graft copolymer resin (B) prepared so as to be compatible therewith. 0 to 15 parts by weight, preferably 0 to 15 parts by weight, based on
Weigh and mix in the range of 10 parts by weight. The mixed compound may be a dry blend, but more preferably subjected to a melt-kneading step and melt-mixed. If the amount of each resin is out of the above range, the desired heat resistance or impact resistance of the resin composition cannot be obtained, and a thermoplastic resin composition having good processability cannot be obtained.

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

For example, one or more of these resins in the form of powder, beads, flakes or pellets may be mixed with an extruder such as a single-screw extruder, a twin-screw extruder, or a Banbury mixer, a pressure kneader, The resin composition can be obtained by a kneader such as a roll. In some cases, one or more of these resins after polymerization may be mixed in an undried state, precipitated, washed, dried and kneaded.

As for the order of the mixing and kneading, three kinds of component resins may be mixed and kneaded at the same time. Alternatively, one or more kinds of the component resins may be mixed and kneaded first, and then one or more kinds of the resin may be separately kneaded. The resulting mixture may be later kneaded and kneaded to obtain a desired resin composition.

Further, if volatile components remain in the resin composition, physical properties such as heat resistance may be reduced.Therefore, when mixing and kneading using an extruder, a kneading operation is performed while forcibly devolatilizing. It is good to do. The resin composition thus obtained is used as it is or after being dried for molding.

The resin composition according to the present invention includes a kind and an amount of a lubricant, a release agent, a colorant, an antistatic agent, a flame retardant, an ultraviolet absorber, a light fastness stabilizer, a heat resistance, which do not inhibit the properties of the resin. Various resin additives such as a stabilizer, a filler and a nucleating agent can be added in appropriate combination. Fillers include glass fiber,
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 and the like, and these alone,
A combination of two or more types can also be blended.

The resin composition according to the present invention, injection molding, extrusion molding, by various processing methods such as compression molding, automotive parts,
As molded products such as electric parts, industrial parts, sports equipment, etc.
It can be used for applications requiring excellent low-temperature impact resistance.

〔Example〕

Next, the present invention will be specifically described based on examples as follows. The present invention is not limited to the following examples unless it exceeds the gist.

In the following examples, “parts” means “parts by weight”.

Production Example (1) Production of rubber-reinforced styrene-based graft copolymer resin (B) -I A monomer mixture comprising 70 parts of styrene (hereinafter abbreviated as St) and 30 parts of acrylonitrile (hereinafter abbreviated as AN). (I) was prepared.

In a glass flask equipped with a stirrer, a reflux condenser, a thermometer, and an auxiliary additive, styrene / butadiene / rubber latex (St content 10% by weight, rubber solids concentration 37% by weight, rubber average particle diameter 0.30 μm ) 270 parts (including water),
Then, 100 parts of deionized water was charged, and the internal temperature was raised to 70 ° C. while stirring under a nitrogen stream. 0.01 part of ferrous sulfate, 0.25 part of dextrose and 1 part of sodium pyrophosphate dissolved in a small amount of deionized water were added to the polymerization system.

Then, 25 parts of an aqueous dispersion of cumene hydroperoxide (hereinafter abbreviated as CHPO) was added to the flask (0.5 part of CHPO).
including. ) Over 180 minutes, the monomer mixture (I)
The entire amount was continuously added over 140 minutes, and the polymerization reaction was started at the same temperature. 120 after starting the polymerization reaction
One minute later, 0.2 parts of sodium dodecylbenzenesulfonate was added to the polymerization system. After the start of the polymerization, the graft polymerization reaction was continued at the same temperature for 210 minutes.

Latex obtained after completion of the graft polymerization reaction,
The solution was dropped into a 4% aqueous magnesium sulfate solution heated to 95 ° C., salted out, dehydrated and dried to obtain a powdery rubber-reinforced styrene-based graft copolymer resin (B) -I.

The graft ratio of the obtained rubber-reinforced styrene-based graft copolymer resin (B) -I was 68%, and the weight average molecular weight was 230,000.

(2) Preparation of rubber-reinforced styrene-based graft copolymer resin (B) -II A method similar to (B) -I except that ferrous sulfate was changed to 0.005 part in the production example of (B) -I. And (B) -II
I got

The graft ratio of the obtained rubber-reinforced styrene-based graft copolymer resin (B) -II was 70%, and the weight average molecular weight was 240,000.

(3) Production of rubber-reinforced styrene-based graft copolymer resin (B) -III 1.1 parts of t-dodecylmercaptan as a molecular weight regulator was added to the monomer mixture during the production of (B) -I, (B) -III was obtained in the same manner as (B) -I, except that iron was changed to 0.01 part and dextrose to 0.8 part.

The graft ratio of the obtained rubber-reinforced styrene-based graft copolymer resin (B) -III was 40%, and the weight average molecular weight was 80,000.

As the rubber-reinforced styrene-based graft copolymer resin (B), in addition to the above, those having the following compositions were used in experimental examples.

(B) -IV: rubber content = 35%, rubber average particle diameter = 0.10 μm graft rate = 35%, Mw = 250,000 (B) -V: rubber content = 40%, rubber average particle diameter = 0.15 μm graft % = 55%, Mw = 175,000 (B) -VI: rubber content = 40%, rubber average particle diameter = 0.25 μm graft rate = 30%, Mw = 180,000 (B) -VII: rubber content = 35%, Rubber average particle diameter = 0.20 μm Graft rate = 95%, Mw = 330,000 (B) -VIII: Rubber content = 50%, rubber average particle diameter = 0.25 μm Graft rate = 35%, Mw = 195,000 Examples 1-5 , Comparative Examples 1-8 PBT resin (A) (NOVADUR 5010, Mitsubishi Kasei Corporation
Manufactured by the method described in the above Production Example
Reinforced styrenic graft copolymer resin (B)
Crylonitrile (AN) content at 28% by weight, 220 ° C, 10kgf
Acrylonitrile with a melt flow rate of 6 (g / 10 minutes)
-Copolymer resin (C) comprising styrene copolymer resin
Were weighed at the blending ratio (parts) described in Table 1.
And mixed with a tumbler. The resulting mixture was vented 2
Kneading while removing volatiles using a screw extruder
A pellet of the fat composition was prepared.

From pellets of this resin composition, by injection molding method,
A test piece for measuring physical properties was formed. For molded specimens,
According to the method described in Table 1, in absolutely dry condition, tensile strength, Izod impact strength (notched <23 ° C and -10 ° C)
), The deflection temperature under load and the melt flow rate were measured. The results are shown in Table 1.

Table 1 shows the following.

(1) Since the resin composition according to the present invention uses the rubber-reinforced styrene-based graft copolymer resin (B) prepared so as to be compatible with other mixed resin composition components, high Izod impact even at low temperatures. It has strength (see Examples 1 to 5).

On the other hand, when the rubber-reinforced styrene-based graft copolymer resin (B) out of this range is used, not only the Izod impact strength at a low temperature is lowered but also the Izod impact strength at a room temperature is sometimes low. Comparative Examples 1 to
6).

(2) Since the resin composition according to the present invention contains an appropriate amount of each resin, the balance between the tensile strength, the Izod impact strength, and the mechanical strength, heat resistance, and moldability indicated by the melt flow rate. Is excellent (see Examples 1 to 5).

Further, a resin composition obtained outside the scope of the present invention has a disadvantage that these balances are poor and at least one of the physical properties is poor (see Comparative Examples 1 to 8).

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 25:12) (C08L 55/02 67:02 25:12) (C08L 67/02 51:04 25:12) (C08L 67 / 02 55:02 25:12) (56) References JP-A-61-183344 (JP, A) JP-A-60-262847 (JP, A) JP-A-60-240712 (JP, A) JP JP-A-3-36743 (JP, A) JP-A-3-47852 (JP, A) JP-A-3-7752 (JP, A) JP-A-2-276850 (JP, A) A) JP-A-2-252766 (JP, A) JP-A-2-245505 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 51/00-51/10 C08L 55 / 00-55/02 C08L 67/02-67/03

Claims (1)

(57) [Claims] An aromatic polyester resin (A) of 30 to 70% by weight, a rubber component of 40 to 60% by weight and an aromatic vinyl monomer / vinyl cyanide monomer weight ratio of 80 to 60/20 to 40 (the sum of both monomers is 100) and a copolymer component of 60 to 40% by weight, and the rubber component has a rubber average particle diameter of 0.2 to 1.0 μm, The graft ratio of the copolymer component grafted to the rubber component is 40 to 80.
%, And 100 parts by weight of a resin mixture comprising 30 to 70% by weight of a rubber-reinforced styrene-based graft copolymer resin (B) in which the weight average molecular weight of the ungrafted copolymer component is 150,000 or more; Vinyl monomer component 50-9
A copolymer resin comprising 0% by weight, 0 to 40% by weight of a vinyl cyanide monomer component and 0 to 40% by weight of a methyl methacrylate component (the total of the monomer components is 100% by weight) ( C) A low-temperature impact-resistant resin composition comprising 0 to 15 parts by weight.