JPS63241052A - Styrene copolymer modified with anionically polymerized rubber - Google Patents

Abstract

PURPOSE:To provide the title polymer which has excellent flow characteristics and gives molded products having excellent appearances, gloss and resistance to impact and heat, by copolymerizing a monomer mixture of styrene with acrylonitrile in the presence of a rubbery polymer obtd. by anionic polymn. CONSTITUTION:22% (by weight; the same applies hereinafter) styrene is anionically polymerized with 78% butadiene to obtain a rubbery copolymer (B) having a styrene- insoluble matter content of 0.1% or lower and such a particle size distribution that the ratio of the area of rubber particles having the max. cell diameter not smaller than 0.1mu (volume-average particle size : 0.3-4.0mu) is 2-60% and that of the area of rubber particles having the max. cell diameter smaller than 0.1mu (volume-average particle size) is 98-40% when the total area a of the rubber particles are referred to as 100%. The component B is added to a monomer mixture (A) of 90-55% styrene (a), 10-45% acrylonitrile (b) and optionally 1-30% [based on the total amount of the components (a) and (b)] maleimide monomer (c). The mixture is copolymerized in the presence of a polymn. initiator and an MW modifier to obtain the title copolymer which has a styrene soln. viscosity of 2-250cp (25 deg.C) and in which the component B is dispersed in the form of particles.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention requires a rubber-like polymer produced by anionic polymerization, styrene, and acrylonitrile, which have excellent strength and processability for embroidery carving, as a molding material resin. This invention relates to a rubber-modified styrenic copolymer comprising a copolymer of More specifically, we use a rubber-modified styrenic copolymer that has outstanding resin fluidity during injection molding to change the gloss, appearance, and impact strength of molded products.
The copolymer of the present invention relating to (hereinafter abbreviated as RMC) is used, for example, as a molding material for parts of electrical equipment, automobiles, etc., and specifically, for example, for housings of telephones and computers.

[Conventional technology]

RMC made of SA copolymer of rubber-like polymer, styrene monomer, and 7-crylonitrile monomer is generally ABS.
Widely used as a resin. However, as the applications of such copolymers expand, they are often used for molded products with more complex shapes and thinner walls, and the required performance of the resin is high fluidity and high impact resistance during injection molding. There is a need for a resin that has the following properties. Furthermore, there is a strong demand for improvement in gloss, which is an external appearance characteristic of molded products, and in particular, during injection molding, to improve the gloss of the gate portion and flow end portion of the molded product, and to reduce the difference therebetween. Furthermore, there is a need to reduce patterns (jetting, etc.) near the gate that occur during injection molding.

Until now, RMC has generally been polymerized by emulsion polymerization using rubber latex, and as a means of improving the impact strength of rubber-modified styrenic copolymers, the molecular weight of SA copolymers has been increased, or rubber Measures have been taken to increase the amount of the component, but such methods not only reduce the fluidity of the resin during molding, but also deteriorate the appearance of the molded product, have low gloss at the flow end, and cause problems with the gate area. There was a problem in that the difference in gloss at the end of the flow became large and the occurrence of patterns near the gate became large. Several proposals have been made to improve the impact properties, appearance, and fluidity during molding of RMC, but there is still room for improvement. Although a method using a rubbery polymer has been disclosed, there remains room for improvement in appearance, impact properties, and fluidity during molding. U.S. Pat. No. 4,421,885 discloses a method for controlling the size of rubbery polymers using specific amounts of special organic peroxides, special rubbery polymers, and solvents; No method of achieving the objectives of the invention is disclosed.

[Problem that the invention seeks to solve]

The present invention improves fluidity during molding, high impact strength, and gloss at the end of the flow during injection molding, reduces the difference in gloss between the gate part and the end of the flow, and further improves the flow near the gate during molding. An object of the present invention is to provide an anionically polymerized rubber-modified styrenic copolymer that reduces molding patterns that occur during molding and has an excellent appearance. Such a copolymer is particularly useful as a resin material for a thin-walled molded article having a complicated shape, for example, molded by injection molding.

[Means for solving problems]

The inventors of the present invention have conducted extensive studies in view of the importance of such objectives, and have discovered that the above objectives can be achieved by a rubber-modified styrenic copolymer with a completely new composition compared to conventional knowledge, and have completed the present invention. I ended up doing it.

That is, the present invention provides A. The rubber-modified styrenic copolymer (a) has a styrene solution viscosity of 2 to 250 centiboise at 25°C, and (b) is produced by anionic polymerization with a styrene-insoluble component of less than 0.1wt5. B. The rubber-like polymer in the rubber-modified styrenic copolymer is dispersed in the form of particles, and in an ultra-thin section electron micrograph of the rubber-like polymer, the total rubber is Rubber particles (R
The area ratio of 1) is 2 to 50%, and 0.1w
The area ratio of the rubber particles (R2) is less than 98 to 40
%, and the volume average particle diameter in the ultra-thin section electron micrograph of C0 is 6.3 to 4.0, and the R2
The volume average particle diameter in the ultra-thin section electron micrograph of
．． D. The monomer composition of the SA copolymer in the rubber-modified styrenic copolymer is a styrene monomer (ST) and a 7-acrylonitrile monomer (AN). Ratio 90/10 (S/AN
<55/45, E, based on 100 parts by weight of the SA copolymer forming the continuous phase,
Characterized by the fact that the proportion of polymers with a molecular weight exceeding t, ooo, ooo is less than 0.5 parts by weight, and the proportion of polymers exceeding 1,200,000 is less than 0.01 parts by weight. It is an anionically polymerized rubber-modified styrenic copolymer.

The RMC of the present invention has (a) a styrene solution viscosity of 2 to 250 centiboise at 25°C, and (b) a rubber-like polymer produced by ungrooved anionic polymerization with a styrene-insoluble component of (1,1+st%), which has impact resistance. Conventional ABS resins generally use emulsion polymerization rubber latex by radical polymerization as a starting material; The rubbery polymer contains a substantially styrene-soluble rubbery polymer as an impact strength reinforcing agent.The rubbery polymer has a styrene solution having a viscosity of 2 to 250 centivoise at 25°C, preferably 5 to 250 centivoise. 200 centiboise, particularly preferably 5-70
It's centiboise. If it is less than 2 centivoise, the impact resistance is low, and if it exceeds 250 centivoise, it becomes substantially difficult to manufacture the composition of the present invention.

In addition, the styrene-insoluble component must be less than 0.1 wt%; if it is more than 0.1 wt%, the appearance characteristics of the present invention cannot be achieved.

Butadiene-based rubbery polymers produced by anionic polymerization in the present invention are distinguished from rubbery polymers produced by radical polymerization. In the latter case, examples of rubbery polymers produced by anionic polymerization that do not satisfy the objectives of the present invention in terms of gloss, impact resistance, and other properties include solution polymerization Ziegler catalysts, Go
A rubber-like polymer produced using a Li-based catalyst or a Li-based catalyst, for example, Yasuharu Saeki, "Polymer Production Process", p. 2
19-272 (1971), Industrial Research Association. Examples include polybutadiene rubber, butadiene styrene copolymer and other copolymers, preferably butadiene styrene copolymer, particularly preferably butadiene Φ styrene block copolymer. butadiene
In a styrene block copolymer, the styrene content is 3
~28 parts by weight is preferably used to achieve the object of the present invention. Further, the viscosity of the 5% by weight styrene solution, measured at 30°C, is 100 to 2 centipoise, preferably 60 to 2 centipoise, more preferably 40 to 2 centipoise.
5 centivoise, particularly preferably 13 to 5 centivoise can be used.

Conventionally, rubber particles made of a butadiene-based rubbery polymer occluded and/or grafted with a copolymer of a styrene monomer and an acrylonitrile monomer have been produced by radical polymerization. Dispersion (RDR)
Although it is not clear where the outstanding performance of this product comes from, the rubber-like polymer produced by such radical polymerization has a microstructure,
Amount of styrene-insoluble components 1 There are differences in impurities such as emulsifiers contained in the polymer, and especially in the case of block-type butadiene-styrene copolymers, these cannot be substantially reached by radical polymerization. It is inferred that this is related to the structure of

Conceptually, the RMC of the present invention forms a so-called seabird structure consisting of a rubber phase and an SA copolymer phase, which is seen in general rubber-modified styrenic resins. That is, the rubbery polymer has R
A dispersed phase is formed in the form of particles in the MC. on the other hand,
A copolymer of a styrene monomer, an acrylonitrile monomer, and possibly other monomers (generally referred to as SA copolymer) constitutes the continuous phase. Incidentally, the above-mentioned dispersed phase also contains the SA copolymer in a grafted or occluded form. Here, when observed using an ultrathin section electron micrograph (hereinafter referred to as an electron micrograph), the dispersed phase exists in the form of islands, and the continuous phase exists in the form of bubbles.

The continuous phase is a portion that has the property of being dissolved in a 7:3 mixed solvent of methyl ethyl ketone and methanol, while the dispersed phase is a portion that has the property of not being dissolved by the solvent.

The cells referred to in the present invention are small particles observed inside the rubbery polymer particles that are the dispersed phase in the above electron micrograph. The components of these small particles are SA copolymers grafted or occluded with rubbery polymers, and while rubbery polymers are stained with osmium etc. when taking RMC electron micrographs, they resemble a continuous phase. This is the part that remains undyed.

Examples of rubber particles and cells in such electron micrographs include N, M, and old 1 (aleS).

ed, Enc7clopedia of P
olymer 5science andTechn
olog7. Vol, 13. John Wile
7 & 5ons, New York, 1970.
Figure 5 of p. 217 shows a system of rubber and polystyrene. Although this example does not contain acrylonitrile and is different from the copolymer of the present invention, the concept of rubber particles and cells is the same as that of the present invention. In other words, the rubber particles occupy the entire area C in Figure 5, and the cells are further dispersed within the rubber particles, and Figure 5 shows that the maximum number of cells within the rubber particles is 0.1LL or more. Certain rubber particles (i.e. R1)
exemplify.

The method for producing the copolymer of the present invention is not particularly limited, but it is preferably produced using, for example, a continuous bulk or solution polymerization method. To give an example of such a production method, a rubbery polymer is poured into a liquid containing a styrene monomer and an acrylonitrile monomer, stirred, and depending on the case, the temperature is adjusted to 20°C to 70°C to dissolve it. Such a solution is fed to the reactor. Polymerization is carried out using one or more stages, preferably two or more stages of reactors equipped with a Wl stirrer, and a devolatilization step is carried out in which solid components and volatile components such as unreacted monomers and solvents are separated from the final stage of polymerization. Through this process, a copolymer is obtained. In this method, a rubbery polymer dissolved in a monomer is supplied to the first stage polymerization vessel.

In addition, the monomer, polymerization initiator, and chain transfer agent are supplied to the reactor at any stage. Although it is a bulk polymerization method, the rubber-modified styrenic copolymer obtained by this method can contain a rubbery polymer produced by anionic polymerization as rubber particles. This cannot be produced by adding a styrene monomer and an acrylonitrile monomer and performing graft polymerization.

In the RMC of the present invention, when the area of all rubber particles in an electron micrograph is taken as 100%, the area ratio of rubber particles (R1) whose maximum cell diameter within the rubber particles is o, tuL or more is 2. ~60%, and the area proportion of rubber particles (R2) of less than 0.1 l should be 98-40%, the area of R1 is preferably 2-50%, more preferably 2-45%. %, and the area of R2 is preferably 98 to 50%, more preferably H to 55%. If the area of R1 exceeds 60%, the fluidity and impact resistance will be low and the appearance will be poor, and if it is less than 2%, the impact resistance will be low.
If the area of R2 exceeds 88%, the impact resistance will be low, and 50%
If it is less than that, the fluidity and impact resistance will be low and the appearance will be poor. The R
The volume average particle diameter in the electron micrograph of No. 1 is 0.3~
Should be 4.0 l, preferably 0.4 to 2.0 l.
0 l, more preferably 0.4 to 1.5 l, particularly preferably 0.4 to 1.0 l. The R1.R2 must have a volume average particle size of 0.1 to 0.4p in an electron micrograph. The combination of the area and volume average particle diameter of R2 significantly increases the impact strength of RMC made of a copolymer of styrene monomer and acrylonitrile monomer containing a rubbery polymer produced by anionic polymerization. The reason why liquidity remains so high is not clear, but it is surprising based on conventional knowledge.

The volume average particle diameter X is measured as follows.

That is, an electron micrograph of the copolymer was taken at a magnification of 10,000 times using an ultra-thin section method, and 500 to 700 of the rubber particles in the photograph were taken.
The particle diameter of each particle was measured and averaged using the following formula. D
i is the average diameter of the i-th (II-th particle). Average particle diameter x (IL) = ΣD / ΣD 苧n l n
1 (However, n is the number of total rubber particles.) Furthermore, RMC
The rubber particles inside have a cell diameter of 0.1 l or more (
Rubber particles (R1) and rubber particles (R2) of less than 0.1 g may exist, but when determining the volume average particle diameter by the above method, the volume average particle diameter is determined after distinguishing the rubber particles into R1 and R2 in advance. When a rubber particle image and a cell form an elliptical shape in an electron micrograph, the average value of the major axis a and the minor axis is defined as the diameter α. That is, α=(a+b)/22 In the production of R1 and R2 in the RMC of the present invention, a rubbery polymer produced by anionic polymerization is used, for example, 2
In the case of a continuous stage bulk polymerization method, the conversion rate of the first stage monomer to the copolymer is adjusted in the above-mentioned step, and in the first stage polymerization reaction, for 100 parts by weight of the monomer, This is done by using 0.001 to 0.2 parts by weight of organic peroxide. In general, it is preferable to use a small amount of solvent and chain transfer agent, but the smaller the agitation, the larger the amount of solvent and chain transfer agent, the smaller the amount of organic peroxide, the smaller the molecular weight of the rubbery polymer. The larger the conversion rate, the greater the tendency for this adjustment to be.
This can be done in a trial and error manner by those skilled in the art. As the rubbery polymer, preferably a styrene-butadiene copolymer, more preferably a styrene-butadiene block copolymer can be used for the purpose of reducing the size of cells.

In the monomer composition of the SA copolymer in the RMC of the present invention, the ratio of styrene monomer to acrylonitrile monomer is 130.
/1G≦ST/AN <55/45, preferably Be/14<S↑/AM <85/35
, more preferably 8B/14≦ST/AN<89/3
It is 1.

If ST/AM is less than 90/10, the impact strength will be significantly reduced, and if it exceeds 55/45, the fluidity will be extremely poor and the object of the present invention cannot be achieved.

With respect to 100 parts by weight of the SA copolymer constituting the continuous phase in the RMC of the present invention, the proportion with a molecular weight exceeding 1,000,000 is less than 0.5 parts by weight, and the proportion of 1,200,000 parts by weight is less than 0.5 parts by weight.
The proportion exceeding 1,000,000 should be less than 0.01 parts by weight, preferably the proportion exceeding 1,000,000 should be less than 0.2 parts by weight, more preferably less than 0.01 parts by weight. , the proportion exceeding 1,000.000 is 0.5 parts by weight or more, or 1,2
If the proportion exceeding 0.00,000 is 0.01 part by weight or more, the appearance and fluidity will deteriorate even if the other requirements of the present invention are satisfied. Conventionally, attempts have been made to increase the strength of styrenic resins by increasing the molecular weight, but the present inventors believe that excessive molecular weight is unnecessary from the viewpoint of fluidity and impact resistance, and that it improves the appearance. I found it harmful from my point of view. By satisfying these requirements, it is possible to maintain high impact strength and high appearance and fluidity.The reason for this is not clear, but the properties of the rubber particles of the present invention and the SA coexistence of the continuous phase can be maintained. This seems to be due to the interaction of polymer properties. The molecular weight ratio of the SA copolymer in the continuous phase is determined by a conventional method as follows.

Disperse RMC in a mixed solvent of methyl ethyl ketone/methanol 7/3, remove insoluble matter by centrifugation,
The solvent containing the soluble components is poured into about 20 times the amount of methanol and reprecipitated. This precipitate is subjected to PI filtration, dried, and then measured. Gel permeation chromatography is used for the measurement. A calibration curve of elution volume and molecular weight is prepared in advance using a polystyrene standard sample and used as a reference for the molecular weight of the above-mentioned dry product. Note that polymers with a molecular weight of 1000 or less are excluded from the measurement.

The molecular weight distribution of the present invention can preferably be achieved by continuous bulk or solution polymerization methods.

In the RMC of the present invention, 30% of the continuous phase SA copolymer
°C, o, swt% dimethylformamide (DMF)
The reduced viscosity of the solution is preferably 0.5 to 1.0 dl/g,
More preferably O6θ to 0.9 dl/g, particularly preferably 0.6 to 0.85 dl/g. The value that appears is i,
.

If it exceeds 0.5, the fluidity will be extremely deteriorated, and if it is less than 0.5, the impact strength will decrease. Reduced viscosity is a measurement of the above-mentioned dry product.

In the RMC of the present invention, the degree of crosslinking index of the dispersed phase is 8 to 1.
It is preferably 6 times, more preferably 9 to 14 times, particularly preferably 10 to 14 times. The crosslinking degree index of such a dispersed phase is measured by the following method.

Partially dissolve 0.4 g of RM CO in 30 cc of a 7/3 mixture of toluene/methyl ethyl ketone.

After centrifugation, the weight of the insoluble matter swollen with the solvent is weighed (W
+) After weighing, vacuum dry the insoluble matter and weigh again (
W2) The degree of crosslinking index is obtained by dividing ÷2. The crosslinking degree index depends on the amount and type of polymerization initiator, the temperature and residence time during devolatilization treatment, and further depends on the amount of maleimide monomer. Those skilled in the art can set an appropriate degree of crosslinking index by selecting manufacturing process conditions by trial and error. If the crosslinking degree index is less than 8, the impact strength is extremely low and fluidity is also low, and if it exceeds 16, the practical impact strength is low.

The styrenic monomers used in the present invention include styrene, α-methylstyrene, side-chain alkyl-substituted styrene such as α-ethylstyrene, monochlorostyrene, dichlorostyrene, vinyltoluene, vinylxylene, o-t-butyl Examples include styrene, p-butylstyrene, nuclear alkyl-substituted styrenes such as p-methylstyrene, halogenated styrenes such as tribromustyrene and tetrabromostyrene, and p-hydroxystyrene, 0-methoxystyrene, vinylnaphthalene, etc. However, styrene and α-methylstyrene are particularly preferred, and one or more of these styrenic monomers may be used.

The acrylonitrile monomer used in the present invention includes acrylonitrile, methacrylonitrile, fumaronitrile, maleonitrile, α-glyloacrylonitrile, and the like, with acrylonitrile being particularly preferred. One or more such monomers may be used.

In the present invention, a portion of the styrene monomer and acrylonitrile monomer of the copolymer constituents is set at 3% relative to the total of the styrene monomer and acrylonitrile monomer.
0% by weight or less of methacrylic ester monomers such as methyl methacrylate, acrylic ester monomers such as methyl acrylate, and one or more maleimide monomers such as maleimide and N-phenylmaleimide. For the purpose of improving heat resistance, it is preferable to replace the maleimide monomer with 1 to 30 parts by weight.

The anionically polymerized rubber-modified copolymer of the present invention may be added with an antioxidant such as a normal hindered phenol antioxidant, a phosphorus antioxidant, or a sulfur antioxidant to improve thermal stability. A lubricant can also be added to further improve fluidity.

Further, fiber reinforcing agents such as glass fibers, inorganic fillers, colorants, and pigments may be added depending on the purpose. In addition, by mixing partially halogenated organic compound flame retardants such as tetrapromos biphenyl A, decabromo biphenyl ether, brominated polycarbonate, etc. with the 7-ion polymerized rubber-modified styrenic copolymer of the present invention together with antimony oxide, flame retardation can be achieved. It is possible to

The anionically polymerized rubber-modified styrenic copolymer of the present invention is
It can also be blended with resins such as ABS resin, polyvinyl chloride, styrene-acrylonitrile resin, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, nylon 6, nylon 66, nylon 12, polyphenylene oxide, and polyphenylene sulfide for molding.

Hereinafter, specific embodiments of the present invention will be shown by Examples and Comparative Examples, but these are not intended to limit the present invention.

Example 1 A, styrenic copolymer containing rubber particles with large cell diameter (RM
Production of C-A): A rubber-modified styrenic copolymer was produced using a continuous bulk polymerization apparatus in which a preheater and a vacuum tank were connected to the outlet of three reactors equipped with agitators in series. As a rubbery polymer, block SBR (Methi 9F 22% butadiene 78%; the microstructure of the butadiene moiety is vinyl 18 mol%, trans 47 mol%, cis 35 mol%, 5 wt% styrene solution viscosity at 25 ° C. (11 centipoise) was used. 4.81 i parts of rubbery polymer 32 parts by weight of ethylbenzene 1 part by weight
A rubber solution was prepared by adding 45 parts by weight of rubber to a mixed solution of 15 parts by weight of acrylonitrile. This rubber solution is continuously fed into a first thin reactor for polymerization, passed through a third reactor, passed through a preheater maintained at a temperature of 230 to 250°C, and then placed in a vacuum chamber at a vacuum degree of 120 torr. Unreacted monomers and solvent were removed, and the resin was continuously extracted from the vacuum tank to obtain a rubber-modified styrenic copolymer.

Organic peroxide 1509Pm was used as a polymerization initiator, and dodecyl mercaptan was used as a molecular weight regulator. The amount of rubber-like polymer in the rubber-modified styrenic copolymer was calculated from the amount of feed raw materials supplied and the amount of the obtained copolymer. The stirring number of the first reactor was 17 or higher.

B, styrenic copolymer containing rubber particles with small cell diameter (RM
Production of C-B): A mixed solution in which the composition of the rubber solution was changed from A of this example to 5 parts by weight of rubbery polymer, 25 parts by weight of ethylbenzene, 52.5 parts by weight of styrene, and 17.5 parts by weight of acrylonitrile. A rubber-modified styrenic copolymer was produced in the same manner as in Example A, except that the stirring speed in the first reactor was 350 rpm+s and the amount of the molecular weight regulator was reduced.

C. Analytical evaluation of anionically polymerized rubber-modified styrenic copolymer: C-t. Rubber content: 2. The amount of rubber in the resin is 100 parts by weight, and the amount of rubber fed to the reaction system is as described in A. and the amount of copolymer produced.

C-2, average rubber particle diameter (xIL): according to the method described above.

C-3, copolymer of styrene monomer (7 parts by weight) and 7crylonitrile monomer (2 parts by weight) (y+z parts by weight)
Ratio of 7-crylonitrile monomer in y/z:
It was determined from the material balance of the amount of the monomer introduced into the reaction system and the amount of monomer recovered via the vacuum chamber. In addition, for confirmation, SA
For the copolymer, y/z was determined from the value of elemental analysis of N element, and this value coincided with the value of mass balance.

C-4° molecular weight is t, ooo, ooo and 1.20
Ratio exceeding 0,000: according to the method described above.

C-5, determination of cell size: according to the method described above.

D. Evaluation of physical properties D-1, Molding The obtained copolymer was dried at 90°C for 3 hours, and then molded with an injection molding machine at a molding temperature of 240°C and a mold temperature of 40°C.

D-2. Evaluation of physical properties (1) Izot impact strength: Evaluated according to JIS K-7110.

(2) Gloss: Evaluation was made according to JIS K-7105.

A rectangular molded product with a width of 50 mm, a thickness of 2.5 mm, and a length of 150 mm was injection molded. The gate has a width of 50m and a thickness of 0.
Take 1 meter at one end in the length direction, and set the gate part as the starting point of the flow.
The end opposite the gate is the flow end. 2 from the gate part
The gloss of the 5m x 5mm square part with the center of the 5mm distance as the center is the gate gloss, and the distance is 25 m from the end.
The gloss of a square part of 5 x 5 m+s centered at the center of the distance was defined as the bundle end gloss. Generally, the difference in the gloss of the gate part for different RMCs is smaller than the difference in the end part, and the gloss value of the end part is significantly lower than the gloss of the gate part. be.

(3) Evaluation of practical impact strength: Fig. 1 (a)
A falling weight impact strength test was conducted on three parts of the molded product having the shapes shown in ) and (b), part (1), part (2), and part (3). Tip R of falling weight = 8. ha/m,
The inner diameter of the pedestal was 20 m/m.

Part (1) is a part where the thickness changes, part (2) is a part near the corner, and part (3) is a standard part.

(4) Molding pattern near the gate: The pattern of the dull part near the gate (indicated by G) of the molded product having the shape shown in FIGS. 1(a) and 1(b) is an example of the present invention. , a comparative example was used for relative comparison. For each copolymer, 10 molded products were evaluated as 2 points; almost no pattern; 1 point; patterned;
The degree was shown by the average score of the 10 sheets. Note that the gate diameter is a pin gate with a diameter of 1 m+s.

(5) Evaluation of fluidity during molding processing: Evaluation was performed using the oil pressure of the molding machine (short shot oil pressure) required for the lowest injection pressure that does not cause sicoat shot during injection molding. A commercially available ABS resin (reference example) manufactured by a highly rigid emulsion polymerization method was used as a standard, and relative evaluation was performed based on the difference in short shot oil pressure. If the difference value is negative, it indicates that the oil pressure is lower than that of the reference example, and it is determined that the material has good fluidity during molding.

E1 Evaluation results of the anionically polymerized rubber-modified styrenic copolymer of this example: 25 parts by weight of RMC-A and 75 parts by weight of RMC-B were mixed and molded to form the anionically polymerized rubber-modified styrenic copolymer of the present invention. I got it. The results are shown in Table 1. The anionically polymerized rubber-modified styrenic copolymer of this example exhibited outstanding properties in terms of appearance, fluidity during injection molding, and impact strength.

Comparative Example 1 Example 1 (7) Regarding RMC-A, C of Example 1 alone
, D was evaluated using the same method. Both appearance and impact strength were inferior to Example 1.

Comparative Example 2 For RMC-H of Example 2, C and D of Example 1 alone
The evaluation was carried out in the same manner. Impact strength was extremely low.

Examples 2 and 3.4 Rubber-modified styrenic copolymers were obtained by changing the mixing ratio of RMC-A and RMC-B, and evaluated in the same manner as C1D in Example 1. The results are shown in Table 1.

Comparative Example 3 In the production of RMC-A of Example 1, the rubbery polymer contained 0.02 wt% of the styrene-insoluble component and the solution viscosity was 60.
An anionically polymerized rubber-modified styrenic copolymer (RMC-C) was obtained in the same manner as in Example 1A, except that polybutadiene produced by anionic polymerization of centiboids was used. Evaluation was performed in the same manner as in Example 1 C and D. The results are shown in Table 1, and the appearance, fluidity, and impact strength were all poor.

Comparative Examples 4 and 5 Two types of rubber-modified styrenic copolymers were obtained by mixing RMC-C and RMC-A and changing the mixing ratio. Evaluation was made in the same manner as in Example 1 C and D.

The results are shown in Table 1, and the appearance, fluidity, and impact strength were all poor.

Comparative Example 6 A rubber-modified styrenic copolymer (RMC-D) was obtained by emulsion polymerization using a polybutadiene rubber latex different from the rubbery polymer of the present invention. Polybutadiene rubber latex (solid content 20%, volume average diameter of latex 0
．． 20 h) while continuously adding styrene and acrylonitrile. Evaluation was made in the same manner as in Example 1 C and D. Impact strength and fluidity were low.

The styrene-insoluble component of the rubber latex used was 82%.

Comparative Example 7 Comparative Example 6 was the same as Comparative Example 6 except that the volume average diameter of the polybutadiene rubber latex used was 0.6.
A rubber modified styrenic copolymer (RMC-E) was obtained. Evaluation was made in the same manner as in Example 1 C and D. impact strength,
Appearance and fluidity were low. The styrene-insoluble component of the rubber latex used was 50%.

Comparative Example 8 RMC-D and RMC-E were mixed to obtain a rubber-modified styrenic copolymer. Evaluation was made in the same manner as in Example 1 C and D. In particular, the impact strength and fluidity were poor. Example 5 In the production of RMC-A and RMC-B of Example 1,
C of Example 1 except that 1.8 parts by weight of N-phenylmaleimide was added to the raw material fed to the first reactor.
, D was evaluated in the same manner. JIS K-7208
As a result of measuring the Vicat softening point according to
obtained the value of In Comparative Example 1, the result of the same test was 109°C.
Met. It was a rubber-modified styrenic copolymer with excellent heat resistance. Other results are shown in Table 1.

〔Effect of the invention〕

As detailed above, the anionically polymerized rubber-modified styrenic copolymer of the present invention has high fluidity during molding, high impact strength, high gloss at the flow end during injection molding, and It has an excellent appearance with little difference in gloss between the gate part and the flow end, and the molding patterns that occur near the gate during molding are reduced, and it is also copolymerized with a maleimide monomer. has a high heat resistance temperature, and the copolymer of the present invention has extremely high industrial utility value in applications such as parts materials for electrical equipment, electronic equipment, automobiles, office equipment, etc.

[Brief explanation of the drawing]

Figure 1 shows the shape of the molded product used in the practical impact test.
(a) is a plan view, and (b) is a sectional view. G indicates the gate position. Patent applicant Mitsui Toatsu Chemical Co., Ltd. Agent
Patent Attorney Tadashi Wakabayashi Figure 1

Claims (2)

[Claims] (1) A, rubber-modified styrenic copolymer (a) 25°C
(b) contains a rubber-like polymer produced by anionic polymerization with a styrene-insoluble component of less than 0.1 wt% as an impact-resistance reinforcing agent; B. the rubber-modified styrene; The rubber-like polymer in the system copolymer is dispersed in the form of particles, and in an ultra-thin section electron micrograph of the same, the maximum cell diameter within the rubber particles is 0.5%, assuming that the area of the entire rubber particle is 100%. Rubber particles (R1
) has an area ratio of 2 to 50%, and the area ratio of rubber particles (R2) having a maximum cell diameter of less than 0.1 μ is 98 to 40%; The volume average particle diameter in a thin section electron micrograph is 0.3 to 4.0μ, and the volume average particle diameter in an ultrathin section electron micrograph of R2 is 0.1 to 0.
D, the monomer composition of the SA copolymer in the rubber-modified styrenic copolymer has a ratio of styrene monomer (ST) to acrylonitrile monomer (AN) of 90/10≦ST/ AN≦55
/45 and E, for 100 parts by weight of the SA copolymer forming the continuous phase,
Characterized by the fact that the proportion of polymers with a molecular weight exceeding 1,000,000 is less than 0.5 parts by weight, and the proportion of polymers exceeding 1,200,000 is less than 0.01 parts by weight. Anionically polymerized rubber-modified styrenic copolymer. (2) When the total amount of styrene monomer and acrylonitrile monomer as copolymer constituent components is 100 parts by weight,
The anionically polymerized rubber-modified styrenic copolymer according to claim 1, which is a copolymer obtained by replacing 1 to 30 parts by weight of the maleimide monomer with a maleimide monomer.