JP3137768B2 - Recycling method of impact-resistant styrenic resin molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing deterioration of performance of an impact-resistant styrenic resin molded product during recycling.

[0002]

2. Description of the Related Art In recent years, waste of plastic-based products has become a major social problem as a global environmental problem. Above all, impact-resistant styrenic resin moldings are used in large quantities in home appliances such as televisions and refrigerators, and food packaging containers, and recycling thereof has come to be considered to be extremely important. However, conventional impact-resistant styrenic resin molded products using polybutadiene rubber or styrene-butadiene copolymer rubber as a toughening agent have significantly deteriorated rubber parts, and when recycled, have higher impact resistance than the original resin. Significant reduction and coloring, is used only for low-grade applications, or blend a large amount of new impact-resistant resin,
Or it was necessary to blend expensive reinforcing agents.

[0003]

SUMMARY OF THE INVENTION The present invention solves the problems of reduced impact resistance and the problem of coloring, which are problems when recycling conventional impact-resistant styrenic resin molded products. An object of the present invention is to provide a method of recycling an impact-resistant styrene-based resin molded product that can be easily performed at a low cost without significantly changing a manufacturing process, a molding process, and the like of the impact-resistant styrene-based resin. I do.

[0004]

That is, the present invention relates to a partially hydrogenated conjugated diene rubber obtained by hydrogenating 5 to 85% of conjugated diene units of a conjugated diene rubber;
A styrene-based monomer or a mixture of 98 to 75% by weight of a mixture of a styrene-based monomer and a monomer copolymerizable therewith is subjected to radical polymerization by bulk polymerization, bulk suspension polymerization or solution polymerization. Obtained impact-resistant styrenic resin 30-1
An impact-resistant styrene-based resin molded product obtained by molding a resin or a resin composition consisting of 00% by weight and 70 to 0% by weight of another styrene-based resin at a temperature of 200 ° C. or more is collected,
A method for recycling an impact-resistant styrenic resin molded product, comprising crushing into granules or powder, melting at a temperature of 200 ° C. or more, and recycling.

Hereinafter, the present invention will be described in detail. 5 out of the conjugated diene units of the conjugated diene rubber used in the present invention.
The partially hydrogenated conjugated diene-based rubber in which about 85% is hydrogenated is represented by, for example, the following monomer units.

[0006]

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[0007]

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However, R ¹ , R ² , R ³ , R ⁴ , R ⁵ ,
R ⁶ , R ⁷ , R ⁸ , and R ⁹ are any of hydrogen, methyl, and ethyl; R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ are hydrogen, methyl, ethyl, and methoxy; , An ethoxy group, a trialkylsilyl group or a trialkoxysiloxy group. The molar ratios of the monomer units represented by the general formulas i) to v) are represented by A, B, C, D and E, respectively.
(Mol%), the molar ratio E of the styrene monomer is 0 to 34%, and the molar ratio of the conjugated diene monomer (A + B
+ C + D) is preferably 100 to 66%, and the hydrogenation ratio (C + D) / (A + B + C + D) of the conjugated diene monomer is preferably 5 to 85%.

[0009] Above all, for A, A / (A + B
+ C + D) is preferably 10% or more.
/ (A + B + C + D) is preferably 20% or less, and E is 2
It is preferably at most 6%. In particular, for C and D, (C +
D) / (A + B + C + D) is more preferably 9 to 60%, and for B, B / (A + B + C + D) is 0.5 to 1%.
2% is more preferred.

Here, if the hydrogenation ratio of the conjugated diene unit, that is, (C + D) / (A + B + C + D) is too high, the impact resistance of the impact-resistant styrene resin is inferior. Impact resistance after recycling is reduced, and yellowing is liable to occur. On the other hand, if the molar ratio E of the monomer unit v), which is a copolymer component of the conjugated diene, is too large, the impact resistance of the impact-resistant styrenic resin will be poor.

On the other hand, if the molar ratio A of the monomer unit i) is too small, the impact resistance of the impact-resistant styrenic resin is inferior. Impact resistance after recycling of the resin is reduced, and yellowing is particularly severe. Further, the molar ratio B is preferably in an appropriate range. If the molar ratio B is too small, the impact resistance of the impact-resistant styrene resin is poor.

The monomer units i) to v) may be random, block, or tapered. However, it must be in a rubber state at room temperature, and preferably has a glass transition temperature of -50 to -110 ° C.
The temperature is more preferably -70 to -110 ° C for the impact resistance of the obtained styrene resin. Further, the monomer units i) to iv) are preferably random. The monomer units v) may be distributed randomly or in a tapered manner, or may be further distributed as a block at the terminal or central part in the molecule, if necessary.

The viscosity (SV) of the partially hydrogenated conjugated diene rubber used in the present invention is preferably from 5 to 1000 cps (5% styrene solution, 25 ° C.), which is based on the rubber particle diameter in the impact-resistant styrene resin. A reasonable viscosity should be selected to control the viscosity. Further, the preferable viscosity depends on the production process of the impact-resistant styrene resin, and the higher the shear rate at the time of forming the rubber particles, the larger the SV. Generally, in order to obtain a high gloss or transparent impact-resistant styrenic resin, more preferably 5 to 5
In order to obtain a resin having a higher impact resistance by using a low SV rubber of 100 cps, it is more preferable to use 100 to 1000 cps.
Use ps high SV rubber.

The molecular weight distribution of the partially hydrogenated conjugated diene rubber used in the present invention is preferably 1.2 to 5 in terms of Mw / Mn. If the molecular weight distribution is too large, the impact resistance of the impact-resistant styrenic resin is poor, and the molecular weight distribution is 1.
If it is less than 2, it becomes difficult to process or obtain the polymer itself as a rubber, and it becomes difficult to apply the present invention. The molecular weight distribution is measured by a gel permeation chromatograph (GPC) according to a conventional method.

The molecular weight distribution of the partially hydrogenated conjugated diene rubber measured by GPC may be one peak, two peaks or more. The partially hydrogenated conjugated diene rubber used in the present invention is obtained by partially hydrogenating a conjugated diene rubber obtained by a known method. The conjugated diene rubber obtained by a known method generally includes all rubbers used for producing impact-resistant styrene resins. For example, polybutadiene (low-cis polybutadiene and high-cis polybutadiene), styrene-butadiene copolymer (SBR, random and block SBR), polyisoprene, butadiene-isoprene copolymer, natural rubber, etc., among which polybutadiene, styrene -Butadiene copolymer is a preferred example.

The partially hydrogenated conjugated diene rubber used in the present invention can be obtained by partially hydrogenating the above conjugated diene rubber. As the hydrogenation method, any conventionally known method may be used. L. Ramp, eta
1, J .; Amer. Chem. Soc. , 83, 467
2 (1961). Hydrogenation using the triisobutyl borane catalyst described in Hung Yu Chen,
J. Polym. Sci. Polym. Letter
Ed. , 15 , 271 (1977), a method of hydrogenating with toluenesulfonyl hydrazide, or an organic cobalt compound described in JP-B-42-8704.
Hydrogenation using an organoaluminum catalyst or an organonickel-organoaluminum catalyst;
JP-A-8-17103 discloses a method of hydrogenating using a heterogeneous catalyst in which a metal such as Pd and Rh is supported on a carrier.

A particularly preferred method of hydrogenation in the practice of the present invention is disclosed in Japanese Patent Application Laid-Open No. Sho 52-4 using a catalyst which can selectively hydrogenate a 1,2-vinyl bond prior to a 1,4-bond.
No. 1890, or use of a catalyst which can be hydrogenated under mild conditions of low temperature and low pressure.
No. 133203 and JP-A-60-220147.

The method of hydrogenation may be a continuous method or a batch method. The partially hydrogenated conjugated diene-based rubber used in the present invention may be used by blending a non-hydrogenated conjugated diene-based rubber with the partially hydrogenated conjugated diene-based rubber obtained by the above method. However, even in that case, it is necessary that the hydrogenation ratio of the entire rubber is within the range of the present invention, and preferably, the non-hydrogenated conjugated diene rubber is 50% by weight or less based on the rubber used, It is more preferably at most 30% by weight.

The impact-resistant styrenic resin of the present invention contains the above partially hydrogenated conjugated diene rubber in an amount of 2 to 25% by weight, preferably 5 to 20% by weight, more preferably 8 to 15% by weight. It is. If the amount of rubber used is less than this range, the effect of improving the impact resistance aimed at by the present invention is insufficient. On the other hand, if it is used beyond this range, the impact resistance is improved, but the characteristics of the original styrene resin For example, the tensile strength, rigidity, and gloss and other appearance properties are lost, which is not preferable. Further, in the present invention, in addition to the partially hydrogenated conjugated diene rubber used in the present invention, other unvulcanized rubber which is known to be used as a toughening agent is contained in a small amount, for example, 1 to 10% by weight as a toughening agent. It may be. A method for obtaining an impact-resistant styrene resin is a mixture of 2 to 25% by weight of a partially hydrogenated conjugated diene rubber and a styrene monomer or an unsaturated compound copolymerizable with the styrene monomer.
This is a method in which about 75% by weight is subjected to radical polymerization by bulk polymerization, bulk suspension combined polymerization or solution polymerization.

The styrene monomer used in the present invention includes styrene, α-methylstyrene, vinyltoluene such as paramethylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, monochlorostyrene,
Examples thereof include dichlorostyrene, tribromostyrene, and tetrabromostyrene, which are used as one kind or as a mixture of two or more kinds. Examples of the unsaturated compound copolymerizable with the styrene monomer include acrylonitrile, methyl methacrylate, maleic anhydride, and N-phenylmaleimide. A particularly preferred styrenic monomer in the present invention is styrene, which may be used alone or as a mixture of other monomers, wherein the ratio of styrene in the mixture is 50%.
% By weight or more.

When acrylonitrile is used together with styrene, the impact resistance, rigidity, chemical resistance,
It is excellent in terms of heat resistance and the like, and those obtained by copolymerizing maleic anhydride have excellent heat resistance, and those using methyl methacrylate together with styrene provide a transparent impact-resistant resin as MBS. . However, the partially hydrogenated conjugated diene rubber for MBS is composed of 10 to 26 styrene monomers.
Molar% is preferred from the viewpoint of transparency.

The bulk polymerization, which is one of the methods for obtaining the impact-resistant styrenic resin used in the present invention, is generally carried out as follows. First, the partially hydrogenated polymer specified in the present invention is dissolved in styrene, and is heated and polymerized at a polymerization temperature of 50 to 250 ° C. in the case of using no catalyst without using a radical initiator. When a radical initiator is used as a catalyst,
The polymerization is carried out at a temperature of 20 to 200 ° C. in accordance with the decomposition temperature of the radical initiator under appropriate stirring, and the polymerization operation is continued until the reaction rate of styrene becomes a desired value.

In this case, a particularly preferable method for obtaining the impact-resistant styrenic resin of the present invention is to use a radical initiator,
By combining an appropriate chain transfer agent, the ratio of the grafted styrene-based polymer to the partially hydrogenated conjugated diene-based rubber when the polymerization addition ratio of the styrene-based monomer is 30% is 20%.
It is preferable to control so as to be 60 to 60% by weight, and more preferably 30 to 55% by weight.

By appropriately increasing the graft ratio in this way, it is possible to further increase the impact resistance and to minimize the decrease in the impact resistance of the recycled resin. on the other hand,
If the graft ratio is too high, the flow of the whole resin will be poor, and a processing problem will occur. Examples of the radical initiator include 2,2-bis (t-butylperoxy) butane and 2,2
-Bis (t-butylperoxy) octane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, n-butyl-4, 4-bis (t-
Peroxy ketals such as butyl peroxy) valerate.

Di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α '
-Bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-
Dialkyl peroxides such as butylperoxy) hexyne-3.

Acetyl peroxide, isobutyroyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, m
Diacyl peroxides such as trioil peroxide;

Diisopropyl peroxy dicarbonate, di-2-ethylhexyl peroxy dicarbonate, di-n-propyl peroxy dicarbonate, dimyristyl peroxy dicarbonate, di-2-ethoxyethyl peroxy dicarbonate, dimethoxy isopropyloxy dicarbonate, dimethoxy Peroxydicarbonates such as (3-methyl-3-methoxybutyl) peroxydicarbonate.

T-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxypivalate, t-butyl peroxy neodecanoate,
Cumyl peroxy neodecanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxy-3,3,5-trimethylhexanoate, t-butyl peroxy laurate, t-butyl peroxy benzoate, di- -T-butyl diperoxyisophthalate,
Peroxyesters such as 2,5-dimethyl-2,5-di (benzoylperoxy) hexane and t-butylperoxyisopropyl carbonate.

Ketone peroxides such as acetylacetone peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide and methylcyclohexanone peroxide. t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide,
Hydroperoxides such as 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide and the like can be mentioned. These organic peroxides may be used alone or in combination of two or more.

Examples of the chain transfer agent include α-methylstyrene dimer, n-dodecylmercaptan, t
Mercaptans such as -dodecylmercaptan, 1-phenylbutene-2-fluorene, dipentene, and chloroform; terpenes; and halogen compounds. In the bulk polymerization, a well-known internal lubricant, for example, liquid paraffin is added in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the polymer. When a small amount, usually 30% by weight or less, of unreacted styrene is contained in the produced polymer after completion of the polymerization, the styrene is designed for the purpose of removing the styrene under a known method, for example, removal of the pressure under heating or removal of volatile components. It is desirable to remove by a method such as removal by an extruder.

The stirring during the bulk polymerization is carried out as required. After the conversion of styrene to a polymer, that is, the conversion of styrene, has reached 30% or more, the stirring is stopped or relaxed. It is desirable to do. Excessive stirring may reduce the strength of the resulting polymer. If necessary, polymerization may be carried out in the presence of a small amount of a diluting solvent such as toluene or ethylbenzene, and after the polymerization is completed, these diluting solvents may be removed by heating together with unreacted styrene.

Further, bulk suspension combined polymerization is also useful for producing the impact-resistant polystyrene resin of the present invention. In this method, the first half reaction is first performed in a lump, and the second half reaction is performed in a suspension state. That is, the styrene solution of the specific partially hydrogenated conjugated diene rubber of the present invention is subjected to heat polymerization or catalyst addition polymerization in the absence of a catalyst in the same manner as in the case of the bulk polymerization described above, or irradiation polymerization, and the styrene solution is usually 50% of styrene. In the following, it is particularly preferred to partially polymerize up to 10 to 40%. This is the bulk polymerization in the first half.

The partially polymerized mixture is then dispersed in an aqueous medium with stirring in the presence of a suspension stabilizer or both of this and a surfactant, and the latter half of the reaction is completed by suspension polymerization. In the same manner as in the case of the bulk polymerization, washing, drying, pelletizing or powdering as necessary, and practical use. The impact-resistant polystyrene resin thus obtained according to the present invention comprises a hard phase and a soft component of a styrene polymer, that is, a partially hydrogenated conjugated diene rubber graft-copolymerized with styrene or the like and a styrene polymer encapsulated therein. It is composed of coalesced dispersed particles (rubber particles). In this impact-resistant styrenic resin, the gel content (content of the toluene-insoluble portion) is preferably in the range of 8 to 40% by weight, and the swelling index of the gel in the resin in toluene is in the range of 7 to 15. Is preferred.

Further, the molecular weight of the resin part is usually preferably 100,000 to 400,000, more preferably 180,000 to 280,000 in terms of weight average molecular weight. Since the amount of styrene oligomers remaining in the resin affects the heat resistance, it is usually preferably 1% by weight or less, and particularly preferably 0.5% by weight or less when heat resistance is required. The rubber particle diameter is preferably from 0.2 to 5 μm, particularly preferably from 0.2 to 1.5 μm when gloss is required.

In the present invention, another styrene resin is added in addition to the impact-resistant polystyrene resin thus obtained. Other styrene resins include general-purpose polystyrene, other impact-resistant polystyrene, other ABS resins,
There are AES resin, acrylonitrile-styrene resin, styrene-methacrylate copolymer resin, styrene-maleic anhydride copolymer resin, styrene-butadiene block copolymer resin, and the like, and further, methacrylic resin, polyphenylene ether resin, and the like.

The addition of these resins imparts heat resistance, rigidity, impact resistance, and the like, and can be used in a blend depending on the application. The addition amount is 30 to 100% by weight of the impact-resistant polystyrene resin, and the other styrene resin 70
When the amount of the impact-resistant polystyrene-based resin is less than 30% by weight, a resin for recycling having performance such as impact resistance of the present invention cannot be obtained.

Further, the impact-resistant styrenic resin used in the present invention is preferably added with a necessary amount of a stabilizer such as an antioxidant and an ultraviolet stabilizer. As the antioxidant, for example, octadecyl-3- (3,5-di-t-butyl-4)
-Hydroxyphenyl) propionate, 2,6-di-
t-butyl-4-methylphenol, 2- (1-methylcyclohexyl) -4,6-dimethylphenol, 2,
2'-methylene-bis (4-ethyl-6-t-butylphenol), 4,4'-thiobis (6-t-butyl-3
-Methylphenol).

2,4-bis [(octylthio) methyl]
-O-cresol, triethylene glycol-bis [3
-(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], tris (di-nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, dilaurylthiodipro Pionate and the like, and the amount of addition is preferably 100
0.01 to 5 parts by weight, more preferably 0.1 to 5 parts by weight
~ 2 parts by weight.

As the ultraviolet stabilizer, for example, 2- (5
Triazoles such as -methyl-2-hydroxyphenyl) benzotriazole and 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, and bis (2,2,6,6-tetramethyl-4) -Piperidyl)
Hindered amines such as sebacate, and pt
-Butylphenyl salicylate, 2,2'-dihydroxy-4-methoxybenzophenone and the like.

Particularly preferably, triazole-based and hindered amine-based compounds are used alone or in combination. These UV stabilizers are preferably added in an amount of 0.0
It is 1 to 5 parts by weight, more preferably 0.05 to 2 parts by weight. Further, the impact-resistant styrenic resin used in the present invention can be blended with a flame retardant and a flame retardant auxiliary as needed to give a flame retardant formulation. Although there are various types of flame retardants, all known flame retardants are included, and halogen-based flame retardants are mainly effective.

For example, decabromodiphenyl oxide,
Tetrabromobisphenol A, oligomer of tetrabromobisphenol A, tris- (2,3-dibromopropyl-1) -isocyanurate, tetrabromophthalic anhydride, hexabromobenzene, tribromophenylallyl ether, pentabromotoluene, pentabromophenol , Tribromophenyl-2,3-dibromo-
Propyl ether, tris (2,3-dibromopropyl) phosphate, tris (2-chloro-3-bromopropyl) phosphate, octabromodiphenyl ether, octabromobiphenyl, pentachloropentacyclodecane.

Hexabromodichlorodecane, hexachlorobenzene, pentachlorotoluene, hexabromobiphenyl, decabromobiphenyl, tetrabromobutane,
Hexabromodiphenyl ether, ethylene-bis-
(Tetrabromophthalimide), tetrachlorobisphenol A, and oligomers of tetrachlorobisphenol A.

A halogenated polycarbonate oligomer,
Examples include halogenated epoxy compounds, brominated polystyrene such as polychlorostyrene and polytribromostyrene, and poly (dibromophenylene oxide). In the present invention, a phosphorus-based flame retardant is also effective, and examples thereof include ammonium phosphate, tricresyl phosphate, triethyl phosphate, acid phosphate, triphenylphosphine oxide, and red phosphorus.

Examples of the flame retardant aid include antimony trioxide, antimony pentoxide, sodium antimonate, antimony trichloride, antimony pentachloride, zinc borate, barium metaborate, and zirconium oxide. The flame retardant is preferably used in an amount of 5 to 40 parts by weight, and the flame retardant aid is also preferably used in an amount of 2 to 15 parts by weight per 100 parts by weight of the resin.

Further, if desired, various additives commonly used, for example, lubricants, release agents, antistatic agents, coloring agents, various fillers, organic polysiloxanes such as polydimethylsiloxane, mineral oil Etc. can be blended. The impact-resistant styrenic resin used in the present invention is molded at a temperature of 200 ° C. or higher. In addition to general injection molding, extrusion molding, etc., it is molded by a method such as gas injection and used for various purposes. However, in addition to the above, molding in the present invention includes molding into raw material forms such as pellets and strands. The molding temperature is generally a temperature at which the resin sufficiently flows, and an optimum temperature is selected according to the softening temperature, melt viscosity, and type and amount of additives such as mineral oil and type and amount of flame retardant of the matrix resin.

The molding of the impact-resistant styrenic resin using the partially hydrogenated conjugated diene rubber used in the present invention is carried out at a molding temperature of 200 ° C. or more, preferably 400 ° C. or less. Or, even if it is molded at a temperature of 280 ° C. or higher, its performance is hardly reduced. The impact-resistant styrenic resin molded product of the present invention is recovered after use, crushed into a lump, a granular form, or a powdery form, melted at a temperature of 200 ° C. or more, preferably 400 ° C. or less, and recycled. Preferably, it is crushed to a size that can be fed to an extruder, melted in the extruder and recycled. Preferably, the pellets are formed into a single pellet by an extruder, and further added with necessary additives and the like, and finally formed into a molded product and recycled.

As described above, by carrying out the method for recycling an impact-resistant styrenic resin molded product of the present invention,
The obtained recycled resin has almost no impact resistance reduction and coloring that is a problem compared to the original resin, and can be used for various applications such as cabinets, housings, packaging containers, bottles of home appliances similar to the original resin Thus, plastic recycling can be easily performed at low cost.

[0048]

EXAMPLES Some examples will be shown below to show specific embodiments of the present invention, which are intended to more specifically explain the gist of the present invention and are not intended to limit the present invention. is not.

[0049]

Example 1 Using an autoclave with an internal volume of 10 liters and equipped with an squid-type stirrer, 10% by weight of partially hydrogenated polybutadiene having a structure shown in Table 1 in which 20% of butadiene units were hydrogenated, 90 parts by weight of styrene, octadecyl-3 − (3,
After adding 0.3 parts by weight of 5-di-t-butyl-4-hydroxyphenyl) propionate and purging with nitrogen, 0.0
3 parts by weight of 1,1-bis (t-butylperoxy) cyclohexane and 0.06 parts by weight of t-dodecylmercaptan were added, polymerization was started at 110 ° C. while stirring at 30 rpm, and a small amount of sampling was performed on the way. Thereafter, after polymerization for 4 hours, the temperature was sequentially increased to 135 ° C. × 2 hours, 150 ° C. × 2 hours, 170 ° C. × 2 hours to continue the polymerization, and finally devolatilized by heating at 250 ° C. for 45 minutes. The rubber phase was crosslinked and unreacted styrene was removed to obtain impact-resistant polystyrene.

According to the sampling on the way, the ratio of the grafted styrene polymer to the partially hydrogenated polybutadiene at a styrene conversion of 30% was 43% by weight. The ratio of the graft polystyrene to the rubber was measured by vacuum-drying the sampled polymer solution, measuring the solid content, and then dissolving it in a mixed solvent of MEK / methanol 90/10 and centrifuging to remove the insoluble solid (rubber + (Grafted polystyrene) was obtained and calculated by determining the polystyrene content by UV. The average rubber particle diameter is 2.
The gel content was 35% by weight, and the swelling index in toluene was 10.3.

Next, the obtained impact-resistant polystyrene 10
0 parts by weight, 0.5 parts by weight of 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate 0.1 part by weight. After pre-mixing 5 parts by weight, 20 parts by weight of decabromodiphenyl oxide and 6.0 parts by weight of antimony trioxide, the mixture was melt-kneaded at a cylinder temperature of 250 ° C. by a single screw extruder, and injection molded to prepare a test piece. The Izod impact strength was 9.3 kg · cm / cm.

The test piece was accelerated in an oven at 80 ° C. for 500 hours, then pulverized by a pulverizer and extruded at a cylinder temperature of 250 ° C. by a single screw extruder to obtain pellets.
Using these pellets, cylinder temperature 2 with single screw extruder
Test pieces were prepared by kneading at 50 ° C. and injection molding. The Izod impact strength was 8.9 kg · cm / cm, and the Izod impact strength retention was 96%.

[0053]

Example 2 Polymerization of impact-resistant polystyrene using 12 parts by weight of partially hydrogenated polybutadiene and 88 parts by weight of styrene having 35% of butadiene units hydrogenated and having the structure shown in Table 1 or as in Example 1 And finally 260
It was devolatilized by heating at 1 ° C. for 1 hour to obtain impact-resistant polystyrene.

The ratio of the graft polymer to the rubber at a conversion of styrene of 30% was 38% by weight.
The rubber particle diameter is 1.5 μm on average and the gel content is 30 w
The swelling index in t% and toluene was 10.5. Next, 100 parts by weight of the obtained impact-resistant polystyrene, 2-
(3,5-di-t-butyl-2-hydroxyphenyl)
0.5 parts by weight of benzotriazole, bis (2,2,6,
6-tetramethyl-4-piperidyl) sebacate 0.5
After preliminarily mixing 26 parts by weight of tetrabromobisphenol and 6 parts by weight of antimony trioxide, the mixture was melt-kneaded at a cylinder temperature of 260 ° C. by a single screw extruder, and injection molded to prepare a test piece. Izod impact strength is 8.3k
g · cm / cm.

After promoting the deterioration of the test piece as in Example 1, the test piece was pulverized by a pulverizer and extruded by a single screw extruder at a cylinder temperature of 260 ° C. to obtain pellets. A test piece was prepared in the same manner as in Example 1, and the Izod impact strength was 8.1 k.
g · cm / cm, and the Izod impact strength retention rate is 9
8%.

[0056]

Example 3 Impact-resistant polystyrene was prepared in the same manner as in Example 1 except that 40% of butadiene units were hydrogenated and partially hydrogenated polybutadiene having the structure shown in Table 1 was used and the rotation speed was 200 rpm. Polymerization was carried out and finally 250
It was devolatilized by heating at 1 ° C. for 1 hour to obtain impact-resistant polystyrene.

The ratio of the graft polymer to the rubber at a conversion of styrene of 30% was 41% by weight.
The rubber particle diameter was 1.9 μm on average, the gel content was 33% by weight, and the swelling index in toluene was 10.6. Next, the obtained impact-resistant polystyrene was blended in the same manner as in Example 1, melt-kneaded with an extruder, and injection molded to prepare a test piece, and the Izod impact strength was 9.8 kg · cm.
/ Cm. After accelerating the degradation of this test piece in the same manner as in Example 1, it was pulverized by a pulverizer and extruded by an extruder to obtain pellets.

Further, a test piece was prepared in the same manner as in the example,
The Izod impact strength is 9.6 kg · cm / cm,
The Izod impact strength retention was 98%.

[0059]

Comparative Example 1 Polymerization of impact-resistant polystyrene was carried out in the same manner as in Example 1 except that the polybutadiene shown in Table 1 was used as the rubber, and finally, it was heated at 250 ° C. for 30 minutes to devolatilize it. Polystyrene was obtained. The ratio of the graft polymer to the rubber at a styrene conversion of 30% was 45% by weight. The average rubber particle diameter is 1.8μ.
m, the gel content was 36% by weight, and the swelling index in toluene was 9.8.

Next, the obtained impact-resistant polystyrene was
It was blended in the same manner as in Example 1, melt-kneaded with an extruder, and injection molded to prepare a test piece. Izod impact strength is 9.
It was 0 kg · cm / cm. After accelerating the degradation of this test piece in the same manner as in Example 1, it was pulverized by a pulverizer and extruded by an extruder to obtain pellets. Further, a test piece was prepared in the same manner as in Example 1, and the Izod impact strength was 5.2 kg · cm.
/ Cm, and the Izod impact strength retention was 58%.

[0061]

Example 4 Using an autoclave having an internal volume of 10 liters and equipped with an squid-type stirrer, 12% by weight of partially hydrogenated polybutadiene having the structure shown in Table 2 where 20% of butadiene units were hydrogenated, 66 parts by weight of styrene, and 22 parts by weight of acrylonitrile Parts, toluene 20 parts by weight, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] 0.05 parts by weight benzoyl peroxide 0.05 parts by weight, α-methyl Polymerization was started at 90 ° C. while stirring 0.10 part by weight of styrene dimer at 50 rpm in a nitrogen atmosphere.

After 4 hours, at 110 ° C. for 2 hours, 135 ° C.
× 2 hours, 150 ° C. × 2 hours, 170 ° C. × 2 hours, the polymerization was continued, and finally the polymer was heated at 250 ° C. for 45 minutes and devolatilized to obtain an impact-resistant styrene copolymer. The styrene copolymer conversion rate was 30
%, The proportion of graft copolymer to rubber was 48% by weight. The average particle size of the rubber was 0.7 μm (by an electron microscope).

Next, 100 parts by weight of the obtained impact-resistant styrene copolymer, 2- (3,5-di-tert-butyl-2-
After premixing 0.5 part by weight of (hydroxyphenyl) benzotriazole and 0.5 part by weight of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, the mixture was heated at a cylinder temperature of 280 ° C. using a single screw extruder. Melt kneading, injection molding to produce test pieces, Izod impact strength is 25k
g · cm / cm, and the appearance was colorless.

The test piece was accelerated for degradation at 63 ° C. for 100 hours by a sunshine weatherometer, pulverized by a pulverizer, and extruded at a cylinder temperature of 280 ° C. by a single screw extruder to obtain pellets. A test piece was prepared in the same manner as in Example 1, and the Izod impact strength was measured. The result was 24 kg · c.
m / cm, and the Izod impact strength retention was 96%. The appearance remained colorless (milky white).

[0065]

Example 5 Polymerization was carried out in the same manner as in Example 4 using a partially hydrogenated 2-type block SBR having a structure shown in Table 2 wherein 45% of the butadiene units were hydrogenated.
The mixture was devolatilized by heating for one minute to obtain an impact-resistant styrene copolymer. The ratio of the graft copolymer to the rubber at a styrene copolymer conversion of 30% was 45% by weight.

The rubber particle diameter was 0.5 μm on average (according to an electron microscope). Next, the obtained impact-resistant styrene copolymer was melt-kneaded with an extruder in the same manner as in Example 4 and injection molded to prepare a test piece. The Izod impact strength was 22 kg · cm / cm, Is colorless (milky white)
Met. After promoting the deterioration of this test piece in the same manner as in Example 4, the test piece was pulverized by a pulverizer, and then a pellet was obtained by an extruder. Further, a test piece was prepared by injection molding. The Izod impact strength was 21.5 kg · cm / cm, and the Izod impact strength retention was 98%. The appearance was colorless (milky white).

[0067]

Comparative Example 2 Polymerization of an impact-resistant styrene copolymer was carried out in the same manner as in Example 4 except that the polybutadiene shown in Table 2 was used as the rubber. An impact styrene copolymer was obtained. At a copolymer conversion of 30%, the ratio of the graft copolymer to the rubber was 53% by weight. The average particle size of the rubber particles was 0.5 μm (by an electron microscope). Next, the obtained impact-resistant styrene copolymer was melt-kneaded with an extruder in the same manner as in Example 4, and injection molded to prepare a test piece. The Izod impact strength was 25 kg · cm / cm, The appearance was colorless (milky white).

After accelerating the deterioration of the test piece in the same manner as in Example 4, the test piece was pulverized by a pulverizer and then pelletized by an extruder. Further, a test piece was prepared by injection molding. The Izod impact strength was 12 kg · cm / cm, and the Izod impact strength retention was 48%. The appearance was yellow-brown.

[0069]

[Table 1]

[0070]

[Table 2]

[0071]

As described above, the present invention solves the problems of the reduction of impact resistance and the problem of coloring, which are problems when recycling a conventional impact-resistant styrenic resin molded product. This method is inexpensive and easy to carry out without significantly changing the manufacturing process, molding process, and the like of the impact styrene resin, and is extremely useful.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29B 17/00-17/02 C08F 12/08 C08F 36/04

Claims (1)

(57) [Claims] 1. A partially hydrogenated conjugated diene rubber 2 in which 5 to 85% of conjugated diene units of the conjugated diene rubber are hydrogenated.
A mixture comprising styrene-based monomer or a mixture of styrene-based monomer or styrene-based monomer and a monomer copolymerizable therewith, in a mass polymerization, bulk suspension polymerization or solution 30 to 100% by weight of impact-resistant styrene resin obtained by radical polymerization by polymerization and other styrene resin 7
A resin or a resin composition consisting of 0 to 0% by weight at 200 ° C.
Recovering the impact-resistant styrene resin molded product molded at the above temperature, crushing it into a lump, granule or powder, melting it at a temperature of 200 ° C. or more, and recycling it. How to recycle resin moldings.