JPH03263415A - Rubber-modified vinyl aromatic resin composition excellent in gloss and impact resistance - Google Patents

Abstract

PURPOSE:To obtain the subject composition, containing rubber-like polymer particles, having a respective specified particle size distribution and particle structure and dispersed in a specific vinyl aromatic polymer matrix, excellent in molding processability, etc., and capable of providing large-sized molded products, etc., without any gloss unevenness. CONSTITUTION:The objective composition obtained by dispersing preferably 3-20wt.% rubber-like polymer particles compound of 50-95wt.%, preferably 70-90wt.% fine particulate rubber-like polymer having 0.1-0.4mum, preferably 0.15-0.25mum weight-average particle diameter in which >=60wt.%, preferably >=80wt.% thereof has a core-shell structure and 5-50wt.%, preferably 10-30wt.% large particulate rubber-like polymer having 0.8-3.0mum, preferably 1.0-2.0mum weight-average particle diameter and a salami structure in a vinyl aromatic polymer matrix composed of 90-99wt.% vinyl aromatic monomer and 1-10wt.% one or more of a 3-10C alkyl group-containing acrylic acid ester and an 8-20C alkyl group-containing methacrylic acid ester.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin composition with excellent gloss and impact resistance. More specifically, the present invention relates to a rubber-modified vinyl aromatic resin composition that has excellent gloss and impact resistance.

Rubber-modified vinyl aromatic resins, typified by impact-resistant polystyrene, are used in a wide variety of applications, including home appliances and OA equipment, due to their excellent moldability, dimensional stability, and impact resistance. The gloss of the molded product was inferior to that of ABS resin.

In recent years, there has been a demand for high-gloss properties similar to those of ABS resins for these impact-resistant polystyrenes.

-ζ has arrived. In order to achieve this goal, C
Two methods are known: the first method and the second method of reducing the particle size of a rubber-like polymer dispersed in a 1,2C, rubber-modified, aromatic resin. When the thickness is 1z or more than -1 micron, there is a drawback that the impact strength is significantly lowered by 2 and becomes C.

As a recent attempt to improve the balance between impact strength and gloss, a modified vinyl aromatic resin having small-particle rubber-like polymer particles (ζ1 micron or less) and large-particle rubber-like 11 aggregate particles was developed by Tokko Sho. Publication No. 4641467, Special Publication No. 1983-
15], No. 9, US Pat. No. 4,146,589, US Pat. No. 4,214,056, and US Pat. No. 4,493,922. -C, but because the large particles used are larger than 2 microns, the gloss of the molded product is 1 compared to ABS resin.
,2 is inferior, especially in molded products where the gloss gradient is thick - the decrease in gloss is large in areas far from 1), and when molded at low mold temperatures, there are problems such as insufficient gloss. there were.

In order to solve this problem, a rubber-like polymer is dispersed in polystyrene, and the dispersed particles are separated from one small particle part and one large particle part. It shows a distribution consisting of mountains, and the average particle diameter of the small particle A part is 0.1 ~
0.6 microns, and the average particle diameter of the large particle portion is 0.6 microns.
7 to 2.0 microns: fJ, modified polystyrene is used (Japanese Unexamined Patent Publication No. 63412646, Japanese Unexamined Patent Publication No. 1-261444, Jikai "T'l-27564")
! '1 Publication).

The GoJ1 modified polystyrene produced by this method is similar to the conventional GoJ1 modified polystyrene.
・Compared to modified polystyrene, JREPO has a much better balance of gloss and impact strength7, and is one step closer to the gloss of ABS resin, but it is suitable for molded products with complex shapes and large moldings. When molding products, unevenness and flow marks still occur, and problems such as sluggishness remain.

On the other hand, JP-A-62-18454 discloses a rubber-modified styrenic resin containing Q and 0.1 to 15% by weight of acrylic ester in the resin component, but the rubber particle size is large. , because the particle structure is not controlled at °C.
Gloss I/Bevel not enough.

[Problems to be solved by the invention (2)] The present invention has an excellent balance between gloss and impact strength and excellent moldability7, and is suitable for molded products with complex shapes and large molded products. It is an object of the present invention to provide a rubber, modified vinyl, and vinyl aromatic resin composition that exhibits less unevenness even when molded.

[Failure to solve the problem]

The present invention 4, et al., as a result of intensive investigations to solve the problem described in ``3'', have found that rubber-like polymer particles having a specific particle size distribution and particle structure have a specific composition of vinyl aromatic polymer It was discovered that a rubber-modified bi5fluor aromatic resin silk composition having a structure in which it is dispersed during coalescence effectively achieves the object 1 of the present invention, and the present invention was completed.

That is, the present invention provides Go 1, which is formed by dispersing polymer particles in the form of Go 1, which has a particle size distribution consisting of two peaks of small particle portions and large particle portions, in a vinyl aromatic polymer matrix; In the modified vinyl aromatic resin composition, A) 60% by weight or more of the rubbery polymer particles in the small particle portion have a 21 acyel structure, and the weight average particle diameter is 0. In the range of 1 to 0.4 microns.

B) rubber-like polymer particles in the large particle portion have a grainy structure, and the weight average particle diameter is in the range of 0.8 = -3,0 μm; C) rubber-like polymer particles; The ratio of the rubbery polymer particles in the small particle portion to the total weight of the combined particles is 50% to 95% by weight, and D) the vinyl aromatic polymer matrix is a vinyl aromatic monomer. 90-99 flatness% and the following 1), 2): 1) The number of carbon atoms in the alkyl group of the ester moiety is 3 to 10
2) One or more (meth)acrylic acid varnishes selected from methacrylic esters in which the alkyl group in the ester moiety has carbon atoms ranging from 8 to 20. This is a modified vinyl aromatic light heavy composition characterized by comprising:

In the present invention, the vinyl aromatic monomer referred to in the present invention, which cannot achieve the object of the present invention even if any of the above requirements A) to D) is missing, includes 0-methylstyrene in addition to styrene. , m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, p-tert-butylstyrene, etc., nuclear alkyl-substituted styrenes, α-methylstyrene, α-methyl-p-methylstyrene, etc. - Refers to alkyl-substituted styrene, etc., but representative examples include styrene alone or
This is a monomer mixture in which a portion of the monomer is replaced with the above vinyl aromatic monomer other than styrene.

The resin composition of the present invention can be prepared by dissolving a rubber-like polymer having a specific structure in a vinyl aromatic monomer having a specific composition and polymerizing the mixture, as described later.

The present invention will be explained below.

As mentioned above, the resin composition of the present invention has rubber-like polymer particles having a particle size distribution consisting of two peaks, a small particle portion and a large particle portion, dispersed in a vinyl aromatic polymer matrix. First, A) the rubbery polymer particles in the small particle portion account for 60% of the rubbery polymer particles.
The above particles have a core-shell structure and have a weight average particle diameter of 0.
．． It needs to be in the range of 1 to 0.4 microns.

If the rubbery polymer particles in the small particle portion (hereinafter referred to as small particle rubber) do not satisfy the above condition A), the physical properties of the final resin composition obtained will be poor. If more than 60% by weight of the small particle rubber does not have a core-shell structure, or if the weight average particle diameter is less than 0.1 micron or exceeds 0.4 micron, the final product The resulting resin composition has a poor balance between impact strength and gloss. Preferably small particle rubber 8
At least 0% by weight has a core-shell structure, and the weight average particle size is in the range of 0.15 to 0.25 microns. In the above, the weight average particle diameter is the rubber-like polymer particle 1 in the transmission electron micrograph taken by the ultrathin section method of the resin composition.
．． ．． 000 particle diameters were measured and calculated using the following formula.

Weight average particle diameter -Σn;・D='/Σn(-D,'' (where nl is the number of rubbery polymer particles in the particle size.) Next, B) the rubbery weight of the large particle portion It is necessary that the combined particles have a salami structure and have a weight average particle diameter in the range of 0.8 to 3.0 microns. (Measurement of the weight average particle diameter is the same as the above method.) Rubber-like polymer particles in the large particle portion (hereinafter referred to as
It is called large particle rubber. ) does not satisfy the above condition B), the resin composition finally obtained will have poor physical properties. If the weight average particle diameter of the large particle rubber is less than 0.8 microns, the resulting resin composition will have poor impact strength. If the weight average particle diameter of the large particle rubber exceeds 3.0 microns, the final resin composition will have poor gloss.

The weight average particle diameter of the large particle rubber is preferably 1.0 to 2.0.
It is micron.

Next, regarding the ratio of the small particle rubber to the large particle rubber mentioned above, C) The ratio of the small particle rubber to the total weight of the rubbery polymer particles is 5.
It is necessary that the content is 0 to 95% by weight. If the proportion of small particle rubber is less than 50% by weight, the resulting resin composition will have poor gloss. Furthermore, if the proportion of small particle rubber exceeds 95% by weight, the impact strength of the final resin composition will be poor. The preferred proportion of small particle rubber is 70-90% by weight.

The total amount of small particle rubber and large particle rubber in the resin composition is controlled within a range of about 3 to 20% by weight according to a conventional method.

The vinyl aromatic polymer matrix of the resin composition of the present invention comprises D) 90 to 99% by weight of a vinyl aromatic monomer and the following 1)
, 2) Group: ■) Acrylic esters in which the alkyl group in the ester moiety has a carbon number of 3 to 10. 2) Methacrylic esters in which the alkyl group in the ester moiety has a carbon number in the range of 8 to 200. One or more (meth)acrylic esters selected from -L
1.0% by weight.

In the above, (meth)acrylic acid ester is 1 to 10
When the content is % by weight, the resulting resin composition has excellent moldability and a small gloss gradient. If the content is less than 1% by weight, the gloss gradient tends to become large, and if the content exceeds 10% by weight, the heat deformation temperature of the resin composition will be low, making it undesirable as a molding material. The preferred content is 3 to 8% by weight. Examples of (meth)acrylic esters included in the group LL2) include propyl acrylate, iso, butyl acrylate, hexyl acrylate, heptyl acrylate-1., 2-ethylheptyl acrylate-1-12-ethyl butyl acrylate, Acrylic acid esters such as 2-ethylbutyl acrylate and dodecyl acrylate, n,-decyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, octadecyl methacrylate, stearyl methacrylate, etc.
Mention may be made of meth)acrylic acid esters.

Of these, propyl acrylate and 1-butyl acrylate-1, 2-ethylhexyl acrylate are preferred.

A rubber-modified vinyl aromatic resin composition that satisfies conditions A) to D) described above can be produced by various methods. In general, a rubber-modified vinyl aromatic resin composition that satisfies the conditions of Δ) and D) above and B) and D
It can be obtained by mixing a rubber-modified vinyl aromatic resin composition that satisfies the conditions of () with the rubber-modified vinyl aromatic resin composition that satisfies the conditions of (C) above.

The following is a step-by-step explanation.

First, a method for producing a rubber-modified vinyl aromatic resin composition that satisfies the conditions A) and D) will be described.As an example, a polybutadiene block and a vinyl aromatic polymer block will be described.
In the presence of a type 2 or type 3 block copolymer (hereinafter abbreviated as block copolymer) consisting of 2 or 12 monomers, a vinyl aromatic monomer and a small amount of the above (meth)acrylic acid ester are added. can be efficiently obtained by polymerizing a monomer mixture to which is added while stirring. In this case, it is preferable that the vinyl aromatic polymer constituting the block copolymer and the vinyl aromatic monomer have the same or similar chemical structures. In addition, the content of the vinyl aromatic polymer Pro-Nku in the BuI-Co-Nku copolymer is 20~
It is preferably in the range of 45% by weight, 25 to 40% by weight.
It is more preferable that the weight be in the weight range of %.

Next, as a method for producing a rubber-modified vinyl aromatic resin composition that satisfies the conditions R) and D), vinyl It can be obtained by polymerizing a monomer mixture containing an aromatic intermediate and a small amount of the above-mentioned (meth)acrylic acid ester while stirring.

A rubber-modified vinyl aromatic resin composition containing the thus obtained small particle rubber and a rubber containing large particle rubber,
The resin composition of the present invention can be obtained by blending a modified vinyl aromatic resin composition using an extruder or the like. It is also possible to directly produce it by the method described below.

That is, as a first stream, a solution of a rubbery polymer (preferably polybutadiene) in a monomer mixture containing a vinyl aromatic monomer and a small amount of (meth)acrylic acid ester is introduced into a reactor. Continuously feeding the vinyl aromatic monomer until the rubbery polymer is particulate, while independently supplying the vinyl aromatic monomer and a small amount of the vinyl aromatic monomer as a second stream. A solution in which the block copolymer is dissolved in a monomer mixture containing (meth)acrylic acid ester is continuously supplied to another reactor, and polymerization is continued until small particle rubber with a core-shell structure is formed. a first step in which the first stream and second stream of the first step are continuously mixed; and a second step in which the polymerization of the combined streams is completed in the second step. This is a continuous method for producing a rubber-modified vinyl aromatic resin composition consisting of three steps.

This method eliminates the need for blending the small-particle rubber-containing rubber-modified vinyl aromatic resin composition and the large-particle rubber-modified vinyl aromatic resin composition using an extruder or the like. It is extremely economical because the desired resin composition can be obtained quickly.

The impact strength can be further increased by adding polydimethylsiloxane, metal salts of higher fatty acids, and amides of higher fatty acids to the rubber-modified vinyl aromatic resin composition of the present invention.

Furthermore, additives such as dyes and pigments, lubricants, fillers, mold release agents, plasticizers, antistatic agents, and flame retardants can be added to the resin composition of the present invention, if necessary.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.

Reference examples 1 to 12 In the following Examples and Comparative Examples, the following resins were used.

Reference Example 1: Rubber-modified styrenic resin (S-1) Type 2 block styrene-butadiene rubber with a styrene content of 39% by weight (manufactured by Nippon Elastomer ■, Asaprene 670) 1
0 parts by weight was dissolved in a mixed solution containing 84 parts by weight of styrene, 6 parts by weight of butyl acrylate, and a small amount of chain transfer agent, and the solution was continuously fed to a multistage reactor equipped with a stirrer equipped with a deportation device. By thermal polymerization, a rubber-modified styrenic resin (S-1) having a rubber content of 12% by weight and a matrix containing butyl acrylate of 4% by weight was obtained. 95% of rubber particles
The above had a core-shell structure, and the weight average particle diameter was 0.20 microns.

Reference example 2: Rubber modified styrenic resin (S-2) Reference example 1
A rubber-modified styrenic resin (S-2) having a rubber content of 12% by weight and a butyl acrylate content of 4% by weight in the matrix was prepared in the same manner as in Reference Example 1 except that the polymerization was carried out by increasing the amount of chain transfer agent added in . Obtained. More than 95% of the rubber particles have a core-shell structure, and the weight average particle diameter is 0.
．． It was 8 microns.

Reference example 3: Rubber modified styrenic resin (S-3) Reference example 1
Polymerization was carried out in the same manner as in Reference Example 1, except that only styrene was used instead of the mixture of styrene and butyl acrylate in Example 1, to obtain rubber-modified polystyrene (S-3) with a rubber content of 12% by weight. More than 95% of the rubber particles had a core-shell structure, and the weight average particle diameter was 0.20 microns.

Reference Example 4: Rubber-modified styrenic resin (S-4>100 parts by weight of the polymerization stock solution in Reference Example 1 was added with 1° 1-bis(
Reference Example 1 except that 0.08 parts by weight of t-butylperoxy) 3,3.5-)limethylcyclohexane was added.
Polymerization was carried out in the same manner as above to obtain a rubber-modified styrenic resin (S4) having a rubber content of 12% by weight and a butyl acrylate content of 4% by weight in the matrix. More than 95% of the rubber particles were fine dot-like particles with a particle size of 0.05 microns or less.

Reference example 5: Rubber modified styrenic resin (S-5) Reference example 4
Styrene-butadiene random copolymer rubber [manufactured by Asahi Kasei Corporation, Tuffden 2003] is used as a rubbery polymer in
) except that the rubber content was 12.
Weight %, butyl acrylate content in matrix 4
A rubber-modified styrenic resin (S-5) of % by weight was obtained. Less than 40% of the rubber particles had a core-shell structure, and the weight average particle diameter was 0.25 microns.

Reference example 6: Rubber modified styrenic resin (S-6) Reference example 1
In the same manner as in Reference Example 1, except that 76 parts by weight of styrene and 14 parts by weight of butyl acrylate were used instead of 84 parts by weight of styrene and 6 parts by weight of butyl acrylate, the rubber content was 12% by weight and the content of butyl acrylate in the matrix was 11%. Weight% rubber modified styrenic resin (S-6)
I got it.

70% of the rubber particles had a core-shell structure, and the weight average particle diameter was 0.35 microns.

Reference example 7: Rubber modified styrenic resin (L-1) polybutadiene [manufactured by Nippon Elastomer ■, Asaprene 730A]
10 parts by weight were dissolved in a mixed solution containing 84 parts by weight of styrene, 6 parts by weight of butyl acrylate, and a small amount of chain transfer agent, and the same procedure was used as in Reference Example 1 to obtain a rubber content of 12% by weight and a content of butyl acrylate in the matrix of 4% by weight. % rubber-modified styrenic resin (L-1) was obtained. The rubber particles had a salami structure and a weight average particle diameter of 1.4 microns.

-17= 18 Reference example 8: Go J, modified styrene resin (1,,, -2
) Polymerization was carried out by changing the stirring number in Reference Example 7, except that the weight average particle diameter was 1.0 microns and 1.8 microns.
．． A rubber modified styrene resin (■, -2) similar to the modified styrene thread resin (L-1) was obtained.

Reference Example 9: Go J, modified styrene resin (L-3) Polymerization was carried out by changing the stirring number in Reference Example 7, and the weight was 1■!
゛The same rubber-modified styrene-based resin (1,,,-1) except that the average particle diameter was 2.8 microns, and the modified styrene-based resin (L to 3) were added to 1.1.

Reference Example 10: Go J, modified styrenic resin (L-4) Polymerization was carried out by changing the stirring number in Reference Example 7, and the rubber modified styrene resin described in 1 except that the diameter of the weight average particles was 5 mm and 7 mm. Rubber-modified styrenic resin (i) similar to resin (■, -1)
, -4) was obtained.

Reference Example 11: Go J, 9-modified styrene resin (L-5) Polymerization was carried out by changing the stirring number in Reference Example 7, and the weight average particle size was 0° (5 microns, except for the rubber modification described in Same as styrenic resin (i-1), modified styrene I/
A resin (I, -5) was obtained.

Reference Example 12: Rubber-modified styrenic resin (■, -6) Using only styrene instead of the mixture of styrene and butyl acrylate in Reference Example '7, Polymerization was carried out in the same manner as in Reference Example 7. A rubber-modified polyburene (I, ~6) with a rubber content of 12% by weight was obtained. The weight average particle diameter of the rubber particles was 1.3 microns.

Examples 1 to 4 and Comparative Examples 1 to 8 The rubber-modified styrenic resin obtained in the reference example was blended in the proportions shown in Table 1, kneaded and granulated using an extruder to obtain pellets of resin compositions. . Next, a test piece was made using an injection molding machine.
Physical properties were measured. The results are shown in Table 1.

Note that the physical properties were measured by the following method.

・Izotsu impact strength: Based on ASTM D256.

Tensile strength: Compliant with AST D638.

- Flexural modulus: Based on ASTM D790.

Melt flow rate: Compliant with 150-171133.

Bikaft softening point: Based on ASTM 01525.

- Gloss: The gloss value of the gate part and end part of a dumbbell test piece of AST)'l D63B was measured. The incident angle of the light source was measured not only at 60 degrees, but also at 20 degrees. (The smaller the incident angle is, the larger the gloss gradient can be determined, allowing for more precise comparison.) (Here are 1 blank spaces) 1 Example 5 In place of Butyl acrylic 1 and 2 in Reference example 1,
・Reference example 1 except for using ethylhexyl acrylate
In the same manner as in Example 7, a rubber-modified styrenic resin (S-7) having a rubber content of 12% by weight and a 2-ethylhexyl acrylate content of 4% by weight in the matrix was obtained. 95 of rubber particles
% or more had a core-shell structure, and the weight average particle diameter was 0.25 microns.

On the other hand, in place of butyl acrylate in Example 7, 2
-Example 7 except for using ethylhexyl acrylate
Polymerization was carried out in the same manner as above, and rubber containing 1112ffi1%,
2-Ethylhexyl acrylate-1 with a content of 4% by weight
, a modified styrenic resin (■, -7) was obtained. The weight average particle diameter of the rubber particles was 1.2 microns.

The thus obtained rubber-modified styrenic resin (S-7) and (
Example 1
A resin composition was obtained in the same manner as above.

As a result of measuring physical properties, Izot impact strength] 3 kg -
cm/C[11, bending modulus 21.500kg/
c: A, melt flow L/) 6.6 g/10 m1n,
Vicat softening point 1) 5° C1 gloss (incident angle 20 degrees, gate/end) 80/67%.

〔Effect of the invention〕

The resin composition of the present invention not only has an excellent balance of impact strength, gloss, and rigidity, but also has the more desirable properties of excellent moldability and a small gloss gradient. Because of these properties, it is very effective as a resin for producing large injection molded products or molded products that require a particularly clear appearance.

Claims (1)

[Claims] 1. A rubber-modified vinyl aromatic product comprising rubber-like polymer particles having a particle size distribution consisting of two peaks, a small particle portion and a large particle portion, dispersed in a vinyl aromatic polymer matrix. In the group-based resin composition, A) 60% by weight or more of the rubbery polymer particles in the small particle portion have a core-shell structure,
and B) the rubbery polymer particles in the large particle portion have a salami structure, and the weight average particle diameter is in the range of 0.8 to 3. C) the proportion of the small particle portion of the rubbery polymer particles in the total weight of the rubbery polymer particles is from 50 to 95% by weight, and D) the vinyl aromatic polymer matrix contains 90 to 99% by weight of a vinyl aromatic monomer and the following groups 1) and 2): 1) an acrylic ester in which the alkyl group in the ester moiety has a carbon number of 3 to 10; 2) an alkyl group in the ester moiety; One or more (meth)acrylic esters selected from methacrylic esters having a carbon number of 8 to 20
A rubber-modified vinyl aromatic resin composition characterized in that it comprises 10% by weight.