JPS6114245A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE:A thermoplastic resin composition having excellent impact resistance, moldability, and heat resistance, prepared by mixing two kinds of copolymers consisting of alpha-methylstyrene and vinyl cyanide with a specified rubber-modified thermoplastic resin. CONSTITUTION:A resin composition which consists of a copolymer (A) composed of 76-82wt% alpha-methylstyrene, 18-24wt% vinyl cyanide, and 0-6wt% other monomer copolymerizable with these monomers, a copolymer (B) composed of 50-74wt% alpha-methylstyrene, 26-33wt% vinyl cyanide, and 0-24wt% other monomer copolymerizable with these monomers, and a rubber-modified thermoplastic resin (C) obtained by the graft copolymerization of 30-80wt% aromatic vinyl monomer, vinyl cyanide and, if necessary, other monomer copolymerizable with these monomers in the presence of 20-70wt% rubber-like polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a thermoplastic resin having excellent impact resistance, moldability and heat resistance.

``Prior art'' Thermoplastic resin, which is made by graft copolymerizing styrene and acrylonitrile to polybutadiene rubber, has become widely used as a resin (ABS resin) with excellent impact resistance and heat resistance. As performance increases in the light electrical and automobile fields, there is a strong demand for improved heat resistance of structural materials. It is being but,
Generally, when the α-methylstyrene content is increased, the heat resistance improves, but on the other hand, the ice crushing strength and molding processability are greatly reduced, making it impossible to obtain the balanced quality desired in the market.

"Problem to be solved by the invention" This is the heat resistance of α-methylstyrene-containing ABS resin,
This is because impact resistance and moldability depend on the composition ratio of the polymerization components α-methylstyrene and acrylonitrile (which influences the glass transition temperature of the I-rimer) and molecular weight. That is, on the one hand, when the glass transition temperature increases, heat resistance improves, impact resistance decreases, and moldability decreases, and on the other hand, as the amount of particles increases, impact resistance increases and moldability decreases, so simply changing the composition or molecular weight Conventional methods of changing the material have not yielded a product that satisfies heat resistance, impact resistance, and workability.

As a result of various studies, the present inventors discovered two types of copolymers: an α-methylstyrene-acrylonitrile copolymer with a high α-methylstyrene content and an α-methylstyrene-acrylonitrile copolymer with a relatively low α-methylstyrene content. By combining a composition in which the above mixture is used in a specific range and a graft copolymer to a rubbery polymer, a thermoplastic resin composition with excellent heat resistance, impact resistance, and moldability can be obtained. Based on this finding, the present invention has been accomplished.

"Means for Solving the Problems" The present invention consists of 76-82% by weight of α-methylstyrene, 18-24% by weight of vinyl cyanide, and 0-6% by weight of other monomers copolymerizable with these monomers. % and 50-74% by weight
, a copolymer (B) consisting of 26-33% by weight of vinyl cyanide and 0-24% by weight of other monomers copolymerizable with these monomers, and a rubber-like polymer 20-70%.
Graft copolymerization of 30 to 80% by weight of an aromatic vinyl monomer, a vinyl cyanide monomer, and optionally another vinyl monomer copolymerizable with these monomers in the presence of 30 to 80% by weight. The present invention relates to a thermoplastic resin composition characterized in that it is a mixture consisting of a rubber-modified thermoplastic resin (C) obtained by ^・The present invention will be explained in detail below.

What is important in the present invention is that by using together a component with high heat resistance and a high α-methylstyrene content and a component with a relatively low α-methylstyrene content that imparts toughness, the rubber-modified resin and In the composition, heat resistance,
The objective is to obtain a composition with excellent impact resistance and moldability.

The copolymer with high heat resistance is α-methylstyrene (hereinafter a).
MS) 76-82% by weight, preferably 78-81% by weight and acrylonitrile (hereinafter referred to as AN7) 18-2
A copolymer consisting of 4% by weight, preferably 19 to 22% by weight, and 0 to 6% by weight of other monomers copolymerizable with these monomers, preferably in which the chains in the copolymer are +aNi
s-(tMs-ctM8-)0-10%, (-ct
MS-(!MS-AN-)-5F1 or higher, MOAN
-(WS -AN-) 45% or less ((aMs),
If the amount of aMS is less than 76% by weight, sufficient heat resistance cannot be obtained, while if it exceeds 82% by weight, This is not preferable because the thermal deterioration stability deteriorates. The copolymer (B) that imparts toughness is α-methylstyrene 50-74
A copolymer consisting of preferably 60 to 72% by weight, 26 to 33% by weight of acrylonitrile, preferably 28 to 31% by weight, and 0 to 24% by weight of a monomer copolymerizable with these monomers, Preferably, in the chain in the copolymer + width s - (1'Ms - 岨S ÷ and brocade - 岨5-A
It is a copolymer in which the proportion of N is 50 or less. cQ/i
When the amount of S is less than 50% by weight, heat resistance is insufficient,
On the other hand, if it exceeds 74% by weight, processability and impact resistance will be insufficient, which is undesirable. More preferably, the intrinsic viscosity [η] (methyl ethyl ketone 3
copolymer) at 0°C) is 0.2 to 0.5, preferably 0.25 to 0.45,! The i' shoulder copolymer (J3) has a molecular weight of 0.4 to 0.8, preferably 0.5 to 0.7. In each case, if the intrinsic viscosity is below the range, the impact resistance will be low, and if it exceeds the range, the processability will be poor, which is not preferable.

In addition, in order to obtain a composition with excellent heat resistance, impact resistance, and moldability, the weight ratio of copolymer/(copolymer + (B)) is 0.4 to 0.8, preferably 0. It is preferable to mix within the range of .5 to 0.75 degrees. If the content of the copolymer (I) exceeds this ratio, the impact resistance will be poor, and if it becomes less than this ratio, sufficient heat resistance will not be obtained, which is not preferable. Copolymer (g).

In (B), as monomers copolymerizable with α-methylstyrene and acrylonitrile, styrene, styrene derivatives such as nuclear bromine-substituted styrene, nuclear chloro-substituted styrene, nuclear methyl-substituted styrene, methyl acrylate, ethyl acrylate, There are acrylic acid and methacrylic acid esters such as methyl methacrylate and ethyl methacrylate.

Rubber-modified thermoplastic resin (C) is a rubbery polymer 20 to 70
% by weight (preferably 35-65% by weight) of aromatic vinyl monomers, vinyl cyanide monomers, and optionally 30-80% by weight of other vinyl monomers copolymerizable with these monomers. %, preferably 65 to 35% by weight, is a rubber-modified thermoplastic resin obtained by graft copolymerization.

Examples of rubbery polymers include polybutadiene, acrylonitrile-butadiene copolymer rubber, styrene-butadiene copolymer rubber, ethylene-propylene copolymer rubber, ethylene-propylene-ethylidene nordernene copolymer rubber, and acrylic rubber. . Aromatic vinyl monomers include atyrene, styrene substituted with bromine, styrene substituted with chloro, styrene substituted with methyl, α-methylstyrene, etc. One type or a mixture of two or more of these can be used, but preferably. is preferably an aromatic vinyl monomer containing 50% by weight or more of styrene. Vinyl cyanide monomers are acrylonitrile and methacrylonitrile. Jl==)rill is preferred. Other copolymerizable monomers include methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate.

When the content of the rubbery polymer in the rubber-modified thermoplastic resin (C) decreases by 20 degrees, (A), (B), (
In relation to the content range of rubbery polymer in the thermoplastic resin composition obtained by mixing C.
), ψ) The mixing ratio of components is reduced, resulting in sufficient heat resistance.
fart.

On the other hand, if the amount exceeds 70%, the amount of grafted resin component to the rubbery polymer will be small, and the effect of imparting impact properties will be reduced. The ratio of the graft component to the rubbery polymer (grafting ratio) is preferably 30% by weight or more.

The content of the rubbery polymer component in the mixture (B) and (C) must be in the range of 10 to 25% by weight based on the obtained thermoplastic resin composition. If the weight is less than 10, the impact resistance is low.25
If it exceeds % by weight, the rigidity will be low, resulting in a decrease in heat resistance.

The thermoplastic copolymers (A) and (B) for obtaining the thermoplastic resin composition according to the present invention can be obtained by emulsion polymerization, solution polymerization, suspension polymerization, etc., but the preferred manufacturing method is emulsion polymerization. It is polymerization. The above (A) and (B) and the rubber-modified thermoplastic resin can be mixed as desired in the form of an emulsified latex, a powder, a pellet, or a combination thereof.

In the final mixing of (A), (B), and (C) or in the previous step thereof, it is preferable to remove volatile components such as residual monomers from the composition. If volatile components remain, the effects intended by the present invention in terms of heat resistance etc. cannot be sufficiently obtained.

"Example" The present invention will be specifically described below using Examples. Parts by weight and weight % in Examples and Comparative Examples are expressed as parts and %.

200 parts of ion-exchanged water, 2.5 parts of potassium oleate,
80 parts of α-methylstyrene, 10 parts of acrylonitrile,
0.4 parts of tertiary-dodecyl mercaptan was charged into a reactor purged with nitrogen, and emulsified with stirring under a nitrogen stream. After raising the temperature in the reactor to 75°C, 25 parts of sodium tetrasulfate, 0.35 part of glucose, ferrous sulfate,
A solution prepared by dissolving 1 part of os in 20 parts of ion-exchanged water was added, and then 1 part of cumene hydroguoxide was added to initiate polymerization. After continuing the polymerization for 1 hour, 10 parts of acrylonitrile was continuously added over 4 hours. After the addition was completed, the polymerization was continued for another 2 hours, and then the polymerization was completed.

The obtained copolymer latex was coagulated and recovered using calcilum chloride, and after washing with water, a dried copolymer A-1 was obtained.

In order to determine the composition of this copolymer A-1, the nitrogen content was determined by the Coleman nitrogen analysis method, and the amount of acrylonitrile was measured and found to be 21%.

In addition, to obtain the chain distribution, dissolve in tetrahydrofuran -
This copolymer purified by isoglono-4-nol precipitation was dissolved in deuterated chloroform to measure C1C13N, and among the peaks appearing at 140 to 150 ppm (TMS internal standard), the peaks in the range of 141 to 144 were determined as +AN.
-(XR7IS-AN+linkage, 144.5-147 p
The peak in the pm range is +CQ/iS-CtMS-Ha ÷ chain, the peak in the range 147.5 to 150 ppm is +ct
Ms-cIMs-藺s-) was assigned as one linkage, and the linkage distribution was determined from the area ratio. This copolymer is ÷AN-45-AN
+ chain 27.6% -E-aMs -ayis-AN child chain 65.2%, ÷(XMS -(L'MS -1m
The SM renzi was 7.2 yen. [η] (methyl ethyl ketone at 30°C) was 35 ml.

A-2, A-3, A-4 in Table 2 using the same method as A-1
A copolymer was obtained.

200 parts of ion-exchanged water, 2.5 M of potassium oleate,
70 parts of α-methylstyrene, 30 parts of acrylonitrile,
0.4 part of tertiary-dodecyl mercaptan was charged into a reactor purged with nitrogen and emulsified with stirring under a nitrogen stream.

After raising the reactor internal temperature to 40°C, 0% sodium pyrophosphate was added.
．． 25 parts, glucose 0.35 part, ferrous sulfate 0.005
A solution prepared by dissolving 20 parts of ion-exchanged water was added thereto, and then 0.2 parts of cumene hydroperoxide was added to initiate polymerization.

After initiation, the polymerization vessel jacket was kept at 60°C for 3 hours until the polymerization was completed. The copolymer was recovered as a powder in the same manner as copolymer A-1. The acrylonitrile content of this copolymer was 29%. Also, 廿αMS−αMS−αM
The content of S+ linkage is 1, -E-cDJls-αMS-A
The content of N+ chains was 15%, and the content of αMS-AN-) chains was 84%. [η] (methyl ethyl ketone at 30°C) was o, 4811/dl.

B-2, B-3, B-4 in Table 3 using the same method as B-1
A copolymer was obtained.

-"11 ah□□□ months. Yoyo 1 60 parts of ion exchange water, 28 parts of styrene, 30 parts of acrylonitrile
part, 1 part of potassium stearate, 0.2 part of tertiary dodecyl mercagulin emulsified solution (,), 80 parts of ion-exchanged water, 60 parts of polybutadiene latex (in terms of solid content) was charged into a reactor equipped with a stirrer and purged with nitrogen, and emulsified. The temperature was increased to 4°C while stirring under a nitrogen stream.
After raising the temperature to 0C, add 20 parts of ion-exchanged water, 0.2 parts of birophosphate, 4 parts of course Q, 0 parts of ferrous sulfate.
．． 0.1 part of cumene hydrono-oxide and 0.1 part of cumene hydrono-oxide were added, and the jacket was kept at 70°C and reacted for 1 hour.Then, the remainder of the emulsified solution (,) of the above monomers, etc. and cumene hydro 0.1 part of peroxide was added continuously into the polymerization system over a period of 3 hours each. After the addition is complete, add 0.0 parts of sodium pyrophosphate to 5 parts of ion-exchanged water.
05 parts, glucose 0.1 part, ferrous sulfate 0.0025 parts
A solution containing cumene hydrono J? -0.025 part of oxide was added and the polymerization was continued for an additional hour to complete the polymerization. An antioxidant was added to the obtained tex and coagulated using calcium chloride. Pass the coagulated material through your mouth, wash it,
A resin powder was obtained by drying.

Examples-1 to 3, Comparative Examples 1 and 2 Thermoplastic copolymer powder A-1, thermoplastic copolymer powder B
-1 and Co9-modified thermoplastic resin powder C-1 were mixed in the proportions shown in Table-1, and the mixture was melt-mixed and extruded using a vented 50Xφ extruder (260℃) while degassing. A pellet was obtained.

The pellets were dried at 80° C. for 2 hours or more, and test pieces were prepared using an injection molding machine (Natsuka Machinery 1570A) with a cylinder set at 240° C., and their properties were measured. The test method and conditions are shown below.

Izotsu impact strength; ASTMD 2561/4" width with notch (R = 0.25) Falling weight impact strength (fracture energy when falling weight) Fluidity (perflow value) Molding machine; Next summer machine 1s-5OA Injection pressure crab 840 ki2 Mold: 20x2 gourd (width x thickness) Mold temperature: 50℃ Heat resistance 1) Heat distortion temperature: ASTM D 648 test piece; 1/2
"Mowing/2' x 5" Conditions: 264 psi load 2) 17-hole heat shrinkage test piece; 1/8" Mowing A" x 5" Conditions: Measured at 120℃ with gear open for 2 hours; 5" Shrinkage ratio in the direction V(A+B)
It has been shown that unexpectedly good results can be obtained in terms of strength, impact resistance, heat resistance, and fluidity by using a mixture in the range of = 0.4 to 0.7.

Compositions of copolymers (1) and (B) having different monomer composition ratios were prepared by following the above manufacturing method. , Table 2 Table 3 Examples 4 to 8, Comparative Examples 3 and 4 Compositions using the copolymers (A) and (B) shown in Tables 2 and 3 are shown in Table 4. Ta.

As is clear from the present examples and comparative examples, when the α-methylstyrene content is less than 76% in a copolymer prison intended to impart heat resistance, the shrinkage, which is a measure of heat resistance, increases. However, the properties of the composition intended by the present invention cannot be obtained. (Comparison between Example 7 and Comparative Example 4) Copolymer (
B) also has an α-methylstyrene content of 50% by weight.
If it is not dripped, the heat resistance is low (comparison between Example 5 and Comparative Example 3), and the object intended by the present invention cannot be obtained.

"Effects of the Invention" As is clear from the above, the present invention provides an α-methylstyrene-acrylonitrile copolymer with a high α-methylstyrene content and an α-methylstyrene-acrylonitrile copolymer with a relatively low α-methylstyrene content.
Methylstyrene-acrylonitrile copolymer ABS
By blending it into a resin, it has become possible to obtain a thermoplastic resin composition that has excellent impact resistance, moldability, and heat resistance, and is well-balanced.

Claims (1)

[Claims] 1. Constituent components: 76-82% by weight of α-methylstyrene, 18-24% by weight of vinyl cyanide, and 0-6% by weight of other monomers copolymerizable with these monomers. Copolymer (A) consisting of 50 to 74% by weight of α-methylstyrene, 26 to 33% by weight of vinyl cyanide, and 0 to 24% by weight of other monomers copolymerizable with these monomers. 20 to 70% by weight of copolymer (B) and rubbery polymer as components
30 to 80% by weight of an aromatic vinyl monomer, a vinyl cyanide monomer, and optionally another vinyl monomer copolymerizable with these monomers are graft-copolymerized in the presence of A thermoplastic resin composition characterized in that it is a mixture composed of the obtained rubber-modified thermoplastic resin (C). 2. The weight ratio of the amount of copolymer (A) to the total amount of copolymers (A) and (B) is A/(A+B) = 0.40 to
0.80, and the content of the rubbery polymer in the entire thermoplastic resin composition is 10 to 25% by weight.