JPH04239015A - Graft copolymer - Google Patents

Abstract

PURPOSE:To obtain a graft copolymer useful as a molding material or an impact modifier excellent in impact resistance and surface hardness by grafting a vinyl monomer onto a polyorganosiloxane-type composite rubber having a specified structure. CONSTITUTION:A composite rubber-type graft copolymer prepared by grafting a vinyl monomer onto a composite rubber having a structure derived by inseparably intertwining a polyorganosiloxane rubber component with a conjugated diene rubber component.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graft copolymer of polyorganosiloxane composite rubber which can be blended with various resins to provide molded products with excellent impact resistance and surface appearance.

0002

[Prior Art and Problems to be Solved by the Invention] Impact-resistant resins generally consist of a rubber phase and a matrix phase, and it is preferable to use a rubber phase with a glass transition temperature (hereinafter abbreviated as Tg) as low as possible. It is said to be advantageous in absorbing impact energy. Tg is -55℃
This is exemplified by the fact that resins using polybutadiene rubber with a Tg of -80°C, such as ABS resins, have better impact resistance than impact-resistant resins using polybutyl acrylate rubber, which has a Tg of -80°C. . From this, it is thought that if polydimethylsiloxane having a Tg of -123°C can be used as a rubber source, an impact-resistant resin superior to ABS will be obtained. However, polyorganosiloxane has poor reactivity with vinyl monomers, making it difficult to form chemical bonds.For this reason, even when polyorganosiloxane is used as a rubber source for impact-resistant resins, it has sufficient performance. It was difficult to

In an attempt to improve impact resistance by forming chemical bonds between polyorganosiloxane and vinyl monomer, US Pat. No. 3,898,300 discloses a polydimethylsiloxane polymer containing vinylsiloxane or allylsiloxane. It is described that a graft copolymer is formed by polymerizing vinyl monomers in an emulsion of It is described that a monomer is grafted, and JP-A-60-252613 describes a graft copolymer using a methacryloyloxy group-containing polyorganosiloxane. Although these have a certain degree of impact resistance improvement effect, a higher improvement effect is required, and there is also a problem that resins to which they are added have poor surface gloss.

In view of this situation, as a result of intensive studies, we have developed a composite rubber obtained by highly efficient graft polymerization of a vinyl monomer onto a composite rubber consisting of a polyorganosiloxane rubber component and a polyalkyl (meth)acrylate rubber component. By combining a rubber-based graft copolymer with various thermoplastic resins, a resin composition can be obtained that provides molded products with excellent impact resistance, weather resistance, and surface appearance, and also has excellent moldability and fluidity. It was discovered that
Publication No. 7, Publication No. 64-79255, JP-A-1-19
(See Publication No. 0746).

However, in these methods, it is necessary to use a large amount of polyalkyl (meth)acrylate rubber in order to improve the compatibility between the polyorganosiloxane component and the thermoplastic resin. However, it cannot be said that the ability to improve impact strength is fully utilized, and there is a demand for something with even higher impact resistance.

[0006] Furthermore, JP-A-64-6012 discloses that first butadiene is polymerized, and then organosiloxane is polymerized in the presence of polybutadiene to form a polybutadiene core.
An attempt has been made to obtain a rubber having a polyorganosiloxane shell and to graft-polymerize an ethylenically unsaturated monomer onto the rubber. However, with this method,
Perhaps because the polymerization of organosiloxane does not proceed smoothly in the presence of polybutadiene, polyorganosiloxane and polybutadiene cannot form an entangled structure that cannot be separated from each other, resulting in a low gel content of the resulting rubber. However, even if such a graft copolymer is blended into a resin, there is a problem in that it does not have sufficiently high impact resistance.

[0007]

[Means for Solving the Problems] The inventors of the present invention have made extensive studies in view of the above circumstances, and have found that if a polyorganosiloxane rubber is emulsion polymerized and a conjugated diene is polymerized in the presence of the latex, a polyorganosiloxane is formed. By creating a structure in which the conjugated diene polymers are intertwined with each other and cannot be separated, it is possible to create a rubber with a high gel content.Furthermore, by controlling the degree of swelling within a specific range, when this rubber is blended with a thermoplastic resin, it is possible to create a rubber with a high gel content. The molded product has excellent impact resistance, the hardness of the resin can be maintained high, the molded appearance has been improved, and if the particle size of the composite rubber is controlled within a specific range, the impact resistance can be improved. We have found that the following is true and have arrived at the present invention.

That is, the gist of the present invention is that the polyorganosiloxane rubber component is 1 to 99% by weight and the conjugated diene rubber component is 99 to 99% by weight.
1% by weight, has a structure in which both components are intertwined with each other so that they cannot be separated from each other, and has a gel content of 80% or more when measured using a toluene solvent, and a swelling degree of 10 to 40. A composite rubber-based graft copolymer is obtained by graft-polymerizing one or more vinyl monomers onto a composite rubber.

[0009] Instead of the above-mentioned composite rubber, one of polyorganosiloxane rubber and conjugated diene rubber, or a simple mixture of both, is used as a rubber source, and one or more vinyl monomers are grafted onto the rubber source. Excellent impact resistance can only be achieved by using a composite rubber as a rubber source, in which the polyorganosiloxane rubber component and the conjugated diene rubber component are intertwined with each other so that they cannot be separated. It is a compounding ingredient that gives

[0010] When the polyorganosiloxane rubber component in the composite rubber exceeds 99% by weight, the surface appearance of molded products obtained from a composition obtained by adding a graft copolymer using this composite rubber to a resin tends to deteriorate. On the other hand, when the conjugated diene rubber component exceeds 99% by weight, the effect of improving the impact resistance of the resulting graft copolymer decreases.

[0011] The composite rubber used in the present invention has a swelling degree of 10 to
It needs to be 40, preferably 15-30. The degree of swelling is the value obtained by dividing the weight of toluene occluded by the composite rubber when the composite rubber is immersed in toluene at 23° C. for 24 hours by the weight of the composite rubber before immersion. That is, when 1 g of composite rubber absorbs 10 to 40 g of toluene, the degree of swelling of this rubber is said to be 10 to 40. If the swelling degree of the composite rubber is less than 10, the impact resistance will decrease. If the degree of swelling exceeds 40, the surface hardness of a molded article obtained from a composition obtained by blending it with a thermoplastic resin will decrease, and the appearance will deteriorate.

[0012] Furthermore, the gel content of the composite rubber used in the present invention was measured by extracting it with toluene at 90°C for 12 hours.
It must be at least 85% by weight, preferably at least 85% by weight. When the gel content is less than 80% by weight, the surface hardness decreases and at the same time, the effect of improving impact resistance also decreases slightly.

[0013] The average particle diameter of the composite rubber is 0.18 μm.
If it is less than 0.4 μm, the impact resistance of the resin composition blended with the resulting graft copolymer tends to decrease, and if it is larger than 0.4 μm, the impact resistance of the resin composition blended with the graft copolymer tends to decrease. Since the surface appearance of the molded product tends to deteriorate, the average particle size should be 0.18 to 0.4.
Preferably, it is in the μm range. Emulsion polymerization is the most suitable method for producing composite rubber with a particle size below the average particle size.
A latex of polyorganosiloxane rubber is prepared by emulsion polymerization, and then monomers for conjugated diene rubber synthesis are added to this latex to impregnate the polyorganosiloxane rubber particles in the latex, and these monomers are polymerized to form a composite. Preferably, rubber is obtained.

Polyorganosiloxane rubber can be prepared by emulsion polymerization using the organosiloxane shown below and a crosslinking agent for polyorganosiloxane rubber (hereinafter referred to as crosslinking agent (I)). (hereinafter referred to as graft crossover agent (I)) can also be used in combination.

Examples of organosiloxanes include cyclic organosiloxanes having three or more membered rings, and those having three to six membered rings are preferably used. Specific examples of preferred cyclic organosiloxane include hexamethylcyclotrisiloxane,
Octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane,
tetramethyltetraphenylcyclotetrasiloxane,
Examples include octaphenylcyclotetrasiloxane,
These may be used alone or in combination of two or more. The amount of cyclic organosiloxane used is preferably 50% by weight or more in the polyorganosiloxane rubber, and 70% by weight or more.
More preferably, it is at least % by weight.

As the crosslinking agent (I), a trifunctional or tetrafunctional silane crosslinking agent, that is, a silane compound having three or four alkoxy groups, is used, specific examples of which include trimethoxymethylsilane, triethoxysilane, etc. Examples include phenylsilane, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, and tetrabutoxysilane. As the crosslinking agent (I), a tetrafunctional one is preferable, and among the tetrafunctional crosslinking agents, tetraethoxysilane is particularly preferable. The amount of crosslinking agent (I) used is preferably 0.1 to 30% by weight, more preferably 0.5 to 10% by weight, based on the polyorganosiloxane rubber.

[0017] As the graft crossover agent (I), the following formula is used.

0
018]

[Chemical formula 1]

(In each formula, R1 represents a methyl group, ethyl group, propyl group or phenyl group, R2 represents a hydrogen atom or a methyl group, n represents 0, 1 or 2, and p represents an integer from 1 to 6.)
A compound etc. that can form a unit represented by is used.

(Meta) which can form the unit of formula (I-1)
Since acryloyloxysiloxane has a high grafting efficiency, it is possible to form effective graft chains and is advantageous in terms of impact resistance. Note that methacryloyloxysiloxane is particularly preferred as a compound capable of forming the unit of formula (I-1).

Specific examples of methacryloyloxysiloxane include β-methacryloyloxyethyldimethoxymethylsilane, γ-methacryloyloxypropylmethoxydimethylsilane, γ-methacryloyloxypropyldimethoxymethylsilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-methacryloyloxypropyldimethoxymethylsilane. Examples include methacryloyloxypropylethoxydiethylsilane, γ-methacryloyloxypropyldiethoxymethylsilane, and δ-methacryloyloxybutyldiethoxymethylsilane. The amount of grafting agent (I) used is 0 to 10% by weight in the polyorganosiloxane rubber.

Polyorganosiloxane rubbers are described, for example, in US Pat. No. 2,891,920 and US Pat. No. 3,294,72
It can be manufactured by the method described in No. 5 specification etc. In the present invention, for example, organosiloxane and crosslinking agent (I
) and, if desired, the graft cross-agent (I), by shear mixing with water using, for example, a homogenizer, in the presence of a sulfonic acid emulsifier such as alkylbenzenesulfonic acid or alkylsulfonic acid. is preferred. Alkylbenzenesulfonic acid is suitable because it acts as an emulsifier for organosiloxane and also serves as a polymerization initiator. At this time, it is preferable to use an alkylbenzenesulfonic acid together with an alkylbenzenesulfonic acid metal salt, an alkylsulfonic acid metal salt, etc., since this is effective in maintaining the polymer stably during graft polymerization.

Polyorganosiloxane rubber latex can be obtained by neutralizing the latex obtained by polymerization with an aqueous alkaline solution such as sodium hydroxide, potassium hydroxide, or sodium carbonate to stop the polymerization of organosiloxane.

The conjugated diene rubber component used in the present invention is obtained by polymerizing 50 to 100% by weight of a conjugated diene monomer and, if desired, 0 to 50% by weight of a vinyl monomer copolymerizable with the monomer. It is. Examples of conjugated diene monomers include butadiene, chloroprene, isoprene, etc., and examples of vinyl monomers copolymerizable with conjugated diene monomers include aromatic alkenyl compounds such as styrene, α-methylstyrene, and vinyltoluene. ; unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile; and alkyl (meth)acrylates in which the alkyl group has 1 to 12 carbon atoms, and two or more of these monomers may be used in combination.

The polymerization of the conjugated diene rubber component is carried out by adding the above conjugated diene monomer or, if desired, further into the polyorganosiloxane rubber latex which has been neutralized by adding an aqueous alkali solution such as sodium hydroxide, potassium hydroxide, or sodium carbonate. After adding a vinyl monomer copolymerizable with this and impregnating it into polyorganosiloxane rubber particles,
This is carried out by the action of a radical polymerization initiator. As the polymerization progresses, the conjugated diene rubber intertwines with the crosslinked network of the polyorganosiloxane rubber forms an intricate structure, yielding a composite rubber latex of the polyorganosiloxane rubber component and the conjugated diene rubber component that are virtually inseparable from each other. .

As the polymerization initiator used here, any of peroxide-based initiators, azo-based initiators, and redox-based initiators in which a peroxide and a reducing agent are combined can be used, but among these, It is preferable to use a redox initiator, particularly a sugar-containing sodium pyrophosphate initiator consisting of a combination of ferrous sulfate, sodium pyrophosphate, dextrose, and dialkyl peroxide, and a disodium salt of ferrous sulfate and ethylenediaminetetraacetic acid. - A sulfoxylate initiator consisting of a combination of Rongalite hydroperoxide is preferred.

[0027] In the polymerization of conjugated diene rubber in the presence of polyorganosiloxane rubber latex, a composite rubber with a relatively small particle size is easily produced, and the particle size is 0.1.
It may be less than 8 μm. Even if a graft copolymer is created using this composite rubber as it is, the resulting graft copolymer can have a somewhat large effect of imparting impact resistance, but the particle size of the resulting rubber can be increased by enlarging it, etc. It is preferable that the thickness falls within the range of 0.18 to 0.4 μm because the effect of imparting impact resistance becomes higher.

This enlargement method involves partially coagulating the rubber latex to increase the particle size of the rubber, and includes a method of adding a copolymer latex of an unsaturated organic acid and an alkyl acrylate, and a method of adding a salt such as sodium sulfate. The former method is preferably used to enlarge the composite rubber of polyorganosiloxane and conjugated diene rubber as in the present invention, and the unsaturated organic acids include acrylic acid,
One or more types selected from methacrylic acid, itaconic acid and crotonic acid are used, and one or more types of alkyl acrylates having an alkyl group having 1 to 12 carbon atoms are used. Note that this alkyl acrylate may be partially substituted with a monomer such as alkyl methacrylate, styrene, acrylonitrile, etc., as long as the amount is less than half of the amount. The ratio of organic acid and alkyl acrylate in the copolymer of this copolymer latex for enlargement is 3 to 30% by weight for the former and 9% by weight for the latter.
It is preferably used in an amount of 7 to 70% by weight. If the organic acid content is less than 3% by weight, the enlargement ability will be small;
If it exceeds % by weight, a large amount of coagulum will be formed during emulsion polymerization of the copolymer, which is not preferable.

The particle size of the enlarged composite rubber can be adjusted by adjusting the amount of the copolymer latex added. The amount of copolymer latex added depends on the particle size of the composite rubber before enlargement and the particle size of the composite rubber to be obtained by enlargement, but in general, 0.1 part of copolymer is added per 100 parts by weight of composite rubber. ~10
Preferably, it is added in parts by weight. If it is less than 0.1 parts by weight, the enlarging effect is small, and if it exceeds 10 parts by weight, the particle size increases, but impact resistance tends to decrease due to changes in the rubber composition.

The particle size of the composite rubber can be determined by measuring the particle size of an ultra-thin section of the composite rubber using a transmission electron microscope. In the present invention, the particle diameters of 150 to 200 ultrathinly sectioned particles were measured using an electron micrograph with a magnification of 20,000 times, and the number average particle diameter was calculated.

In carrying out the present invention, the main skeleton of the polyorganosiloxane rubber component has repeating units of dimethylsiloxane, and the conjugated diene rubber component is butadiene, with repeating units of trans-1,4-polybutadiene as the main component. A composite rubber obtained by thickening a composite rubber with a latex of a copolymer of butyl acrylate and methacrylic acid is preferably used. Such composite rubber can be graft-polymerized with vinyl monomers.

Examples of vinyl monomers to be graft-polymerized to this composite rubber include aromatic alkenyl compounds such as styrene, α-methylstyrene, and vinyltoluene; methacrylates such as methyl methacrylate and 2-ethylhexyl methacrylate; Acid esters; Acrylic esters such as methyl acrylate, ethyl acrylate, and butyl acrylate; Various vinyl monomers such as vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; these may be used singly or in combination. The above are used in combination.

The ratio of the composite rubber to the vinyl monomer in the composite rubber graft copolymer is 15 to 95% by weight of the composite rubber and 5 to 85% by weight of the vinyl monomer, based on the weight of the graft copolymer. It is preferably 25 to 90 weight % of the composite rubber and 10 to 75 weight % of the vinyl monomer. 5% by weight vinyl monomer
If it is less than 85% by weight, when this copolymer is blended with another thermoplastic resin, the graft copolymer will not be sufficiently dispersed in the resin, and if it exceeds 85% by weight, the effect of imparting impact resistance will decrease, so it is preferable. do not have. The composite rubber graft copolymer is obtained by adding the above vinyl monomer to the composite rubber latex and polymerizing it in one step or in multiple stages using radical polymerization technology. They can be separated and recovered by pouring them into hot water containing dissolved metal salts, salting out, and coagulating them. At this time, it is preferable to add an antioxidant/stabilizer such as hindered phenol or thioether.

The composite rubber-based graft copolymer obtained in the present invention can be used as an impact-resistant resin by itself, but it can also be used in combination with various thermoplastic resins.

Examples of thermoplastic resins whose impact resistance can be improved by adding this composite rubber-based graft copolymer include a mixture of polyphenylene ether resin and polystyrene resin;
Polycarbonate resin and/or polyester resin, and at least one vinyl monomer selected from the group consisting of aromatic alkenyl compounds, vinyl cyanide compounds, and (meth)acrylic acid esters 70 to 100% by weight % and other vinyl monomers copolymerizable with these 0 to 30% by weight
Examples include homopolymers and copolymers obtained by polymerizing.

A method for adding the graft copolymer of the present invention to a resin is to mechanically mix it using a known device such as a Banbury mixer, a roll mill, or a twin-screw extruder and form it into pellets. can be mentioned. Extruded pellets can be molded over a wide temperature range;
A normal injection molding machine is used for molding.

[0037] Furthermore, plasticizers, lubricants, flame retardants, pigments, fillers, fiber reinforcing agents, etc. may be added to this resin composition as required.

[0038]

[Example] The present invention will be specifically explained by the following example. In the following description, "parts" and "%" all mean parts by weight and % by weight unless otherwise specified. The Izod impact strength and surface hardness (Rockwell hardness) in each of the Examples and Comparative Examples were measured as follows. Izod impact strength: According to the method of ASTM D-256. (With 1/4” notch) Rockwell hardness: According to ASTM D-785 method.

Reference Example 1 Polymerization of latex for enlargement In a separable flask equipped with a condenser and a stirrer, 200 parts of distilled water and 3 parts of an anionic emulsifier were dissolved.
After heating to ℃ and purging with nitrogen, 0.01 part of ferrous sulfate,
After adding a mixture of 0.03 parts of ethylenediaminetetraacetic acid disodium salt, 0.2 parts of Rongalit, and 5 parts of distilled water, 85 parts of n-butyl acrylate, 15 parts of methacrylic acid, and 0.4 parts of cumene hydroperoxide were added. Mixed liquid 2
The mixture was added dropwise over a period of time, and then kept at 70° C. for 3 hours and then cooled to obtain a latex of a copolymer of n-butyl acrylate and methacrylic acid. Monomer conversion was 97% and pH was 6.2. In the following examples, this latex was used in the case of enlargement.

Example 1 2 parts of tetraethoxysilane, 0.5 part of γ-methacryloyloxypropyldimethoxymethylsilane and 97.5 parts of octamethylcyclotetrasiloxane were mixed to obtain 100 parts of a siloxane mixture. Next, prepare 200 parts of distilled water in which 0.67 parts each of dodecylbenzenesulfonic acid and sodium dodecylbenzenesulfonate are dissolved, add 100 parts of the above siloxane mixture, and add 100 parts of the above siloxane mixture.
After pre-stirring at 10,000 rpm using a homogenizer, emulsifying at a pressure of 200 kg/cm2,
An organosiloxane latex was obtained.

[0041] This organosiloxane latex was transferred to a separable flask equipped with a condenser and a stirring blade, and heated at 80°C for 5 hours while stirring and mixing.
After being left at 20° C. for 8 hours, the pH of this latex was neutralized to 7.5 with an aqueous sodium hydroxide solution to obtain polyorganosiloxane rubber latex (hereinafter referred to as polyorganosiloxane rubber latex-1). The polymerization rate to the obtained polyorganosiloxane rubber was 88.6%,
The average particle size of polyorganosiloxane rubber is 0.12μ
It was m.

34.2 parts of this polyorganosiloxane rubber latex-1 was collected and placed in an autoclave equipped with a stirrer, and a mixed solution of 195 parts of distilled water, 2.0 parts of potassium oleate, and 0.2 parts of dextrose was added. was added, the atmosphere was replaced with nitrogen, the pressure was reduced to 50 mmHg, and 90 parts of butadiene, 0.24 parts of cumene hydroperoxide, and tert-
A mixture containing 0.6 parts of dodecyl mercaptan was introduced into the autoclave, and the liquid temperature was raised to 55°C. 5 during heating
When the temperature reached 0°C, a mixed solution of 0.0036 parts of ferrous sulfate, 0.3 parts of sodium pyrophosphate, and 5 parts of distilled water was introduced into the autoclave to initiate polymerization. Thereafter, the internal temperature was maintained at 55° C. for 7 hours to obtain a composite rubber latex. A portion of this latex was sampled and the average particle size of the composite rubber was measured and found to be 0.14 μm, and the polymerization rate of butadiene was 92.
It was 8%.

157 parts of this composite rubber latex was collected, 3 parts of the latex for enlargement obtained in Reference Example 1 was added at room temperature, and after stirring for 30 minutes to enlarge the particles, potassium oleate was added. An aqueous solution prepared by dissolving 1.0 part in distilled water was added to stop the enlargement. A portion of the composite rubber latex after enlargement was collected, dropped into methanol to separate the composite rubber, dried to obtain a solid, and heated in toluene at 90°C.
After extraction for 12 hours, the gel content was measured to be 88.7% by weight, and the degree of swelling after immersion in toluene at 23°C for 24 hours was measured to be 32.6. Moreover, the number average particle diameter of the composite rubber after enlargement was 0.24 μm.

[0044] This composite rubber latex was heated to 70°C, and 12.5 parts of acrylonitrile, 37.5 parts of styrene, and 0.225 parts of cumene hydroperoxide were mixed therein as the first stage of graft polymerization. The solution was added dropwise over 60 minutes, the solution temperature was maintained at 75°C for 50 minutes, and then acrylonitrile 1 was added in the second stage of graft polymerization.
A mixed solution of 2.5 parts of styrene, 37.5 parts of styrene, 0.1 part of octyl mercaptan, and 0.225 parts of cumene hydroperoxide was added dropwise over 60 minutes, and then the temperature was maintained for 60 minutes to complete the polymerization. did. The polymerization rates of acrylonitrile and styrene were 98.9% and 98.1%, respectively, and the number average particle diameter of the graft copolymer was 0.27 μm.

The graft copolymer latex obtained above was gradually added dropwise to the heated 5% by weight aqueous sulfuric acid solution while stirring to coagulate the graft copolymer, which was then filtered and dried. This was supplied to a twin-screw extruder (Werner & Faudler, ZSK-30 type), and the cylinder temperature was adjusted to 240
The resulting pellets were melted and kneaded at 240°C and molded at 60°C using an injection molding machine (Promat 165 model: Sumitomo Heavy Industries, Ltd.).
4", 1/8" thick specimens were injection molded and measured for Izod impact strength (23°C, 1/4" notch) and Rockwell hardness. Izod impact strength was 39.5k.
g・cm/cm, Rockwell hardness (R scale) is 8
It was 9.6.

Examples 2 to 6 The ratio of polyorganosiloxane rubber latex-1 and polybutadiene was adjusted as shown in Table 1, and the ratio of cumene hydroperoxide and t during polybutadiene polymerization was adjusted.
Enlarged composite rubber latexes were obtained in the same manner as in Example 1 except that the amounts of ert-dodecyl mercaptan were changed to 0.27 parts and 0.67 parts, respectively, and their gel content, degree of swelling,
The number average particle diameter was measured, and a composite rubber graft copolymer was obtained in the same manner as in Example 1 except that these composite rubber latexes were used, and test pieces were created from these graft copolymers. evaluated. The results are shown in Table 1.

[0047]

[Table 1]

From the above table, it can be seen that good performance is exhibited over a wide range of the ratio of polyorganosiloxane rubber to polybutadiene in the composite rubber.

Comparative Examples 1 and 2 Rubber was prepared in the same manner as in Example 1, except that polyorganosiloxane rubber latex-1 (gel content 90.8, swelling degree 19.9) was used instead of composite rubber latex. Graft polymerization was performed (Comparative Example 1). The performance of the obtained graft copolymer is that the Izod impact strength is 18.7k.
The Rockwell hardness (R scale) was 85.7 in g·cm/cm.

In addition, butadiene was polymerized in the same manner as in Example 1 except that polyorganosiloxane rubber latex-1 was not used and the amount of butadiene introduced into the autoclave was 100 parts. The number average particle diameter of the obtained polybutadiene was 0.07 μm, and the polymerization rate of butadiene was 95.7%. Enlargement and graft polymerization were carried out in the same manner as in Example 1, except that the same amount of the polybutadiene latex obtained above was used instead of the composite rubber latex, and the performance of the obtained graft copolymer was measured. The gel content, degree of swelling, and number average particle diameter of the enlarged polybutadiene are 89.0%, 31.7, and 0.29 μm, respectively.
The Izod impact strength of the graft copolymer is 15.8 kg.
・cm/cm, Rockwell hardness (R scale) is 76
．． 9 (Comparative Example 2).

From the comparison between Comparative Examples 1 and 2 and each Example, it can be seen that if the rubber is not made into a composite rubber, good performance in Rockwell hardness, which is an indicator of impact strength, will not be achieved.

Examples 7 to 9, Comparative Examples 3 to 5 Graft copolymers were obtained in the same manner as in Example 1, except that the amount of mercaptan used during the polymerization of butadiene was changed to the amount shown in Table 2. Hardness was measured. Table 2 shows the gel content and degree of swelling of the composite rubber obtained. The number average particles of the composite rubber after enlargement were all 0.24 μm regardless of the amount of mercaptan. Impact resistance with a gel content of 80% by weight or more and a swelling degree of 10 to 40,
Rockwell hardness was good.

[0053]

[Table 2]

Example 10 160 parts of the composite rubber latex prepared in Example 1 was taken and heated to 70° C. without being subjected to enlargement treatment, and 12.5 parts of acrylonitrile and 37.5 parts of styrene were added thereto.
A mixture of 5 parts of cumene hydroperoxide and 0.225 parts of cumene hydroperoxide was added dropwise over 60 minutes, and then held at 75°C for 50 minutes.
5 parts, 37.5 parts of styrene, 0.0 parts of octyl mercaptan.
A mixed solution of 1 part of cumene hydroperoxide and 0.225 parts of cumene hydroperoxide was added dropwise over 60 minutes, and after the dropwise addition was completed, the temperature of the solution was maintained for another 60 minutes, and then the polymerization was completed. The polymerization rates of acrylonitrile and styrene are 97.5% and 96.2%, respectively,
The number average particle diameter of the graft copolymer was 0.16 μm. A graft copolymer was recovered from this latex in the same manner as in Example 1, extrusion shaping and injection molding were performed, and the Izod impact strength and Rockwell hardness (R scale) were measured. Izod impact strength is 24.8 kg・cm/
cm, and the Rockwell hardness was 104.

Example 11 157 parts of the composite rubber latex obtained in Example 1 was collected,
The enlarged composite rubber latex was subjected to the enlargement treatment in the same manner as in Example 1, and the temperature was raised to 70°C, and methyl methacrylate 30
and 0.2 parts of cumene hydroperoxide was added dropwise over 60 minutes, and then graft polymerization was carried out by maintaining the temperature at 70°C for 60 minutes. The copolymer was collected, extruded and injection molded, and its Izod impact strength and Rockwell hardness (R scale) were measured. The Izod impact strength was 21.2 kg·cm/cm, and the Rockwell hardness was 91.

Effects of the Invention As described above, the composite rubber-based graft copolymer of the present invention itself becomes a molded product with excellent impact resistance and surface hardness, and also improves impact resistance when added to other resins. It also shows excellent performance as an impact modifier.

Claims (1)

[Claims] Claim 1: Polyorganosiloxane rubber components 1 to 99
% by weight and a conjugated diene rubber component of 99 to 1% by weight, and has a structure in which both components are intertwined with each other so that they cannot be separated from each other, and the gel content measured using a toluene solvent is 80% or more, A composite rubber-based graft copolymer obtained by graft polymerizing one or more vinyl monomers to a composite rubber having a degree of swelling of 10 to 40.