JP2002088212A - Recycling method for waste plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recycling method whereby a molded article which can endure reuse is obtained from a waste plastic. SOLUTION: By this method, a molded article which is prevented from peeling and can endure reuse is obtained by adding a polyphenylene ether resin and a methyl methacrylate polymer to a waste plastic mixture mainly comprising a polystyrene resin and an ABS resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling molded plastics from waste plastics.

[0002]

2. Description of the Related Art Thermoplastic resins such as polystyrene resin, ABS resin, and polyolefin resin, or their thermoplastic resin compositions are used in home electric appliances, OA, etc. in view of their excellent moldability, mechanical properties, and low cost. It is used in various fields as a molding material for equipment, household goods, electric / electronic parts, automotive parts, etc., and is used in large quantities. Molded articles that are no longer needed because they have been used are often disposed of by incineration or burying in soil. However, the combustion gas generated during the incineration of plastics can cause problems such as air pollution.On the other hand, when buried in the soil, these will not be reduced to the soil, thus resulting in waste pollution. In addition, the capacity of receiving landfills is approaching its limit. In each case, it leads to environmental destruction and is a social problem. For this reason, material recycling that reuses plastics is required.

[0003] Crushed waste plastic pellets collected from home appliances, OA machines and the like that have been subjected to crushing treatment are separated from polyvinyl chloride having a high specific gravity and polyolefin resin having a low specific gravity by a specific gravity separation method. The study of reusing the separated resin, which is easy to remove, has been widely conducted. However, it is difficult to separate a polystyrene resin and an ABS resin having a small specific gravity difference. Further, since the polystyrene resin and the ABS resin are inherently incompatible, if they are blended as they are, peeling will occur and re-peeling will occur. It has been difficult to produce a molded article that can be used.

[0004]

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide a molded article which does not have the above-mentioned problems, suppresses peeling of molded articles, and can withstand actual use. Is what you do.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, surprisingly, a waste plastic mixture mainly composed of a polystyrene resin and an ABS resin was added to a polyphenylene ether-based resin. By adding a resin and a methyl methacrylate-based polymer, exfoliation of the molded article is suppressed, and a molded article that can withstand reuse can be obtained, and further, when a waste plastic mainly containing an α-olefin resin is used. By further adding a hydrogenated product of a block copolymer, the present inventors have found that a further removal of a molded article can be suppressed and a molded article that can withstand reuse can be obtained, and the above object has been achieved.

That is, the present invention relates to (A1) waste plastic mainly composed of polystyrene resin, and (A2) A
(B1) 1-99% by weight of polyphenylene ether-based resin and (B)
2) A method for recycling waste plastic, which comprises mixing 1 to 30% by weight of a resin (B) consisting of 1 to 99% by weight of a methyl methacrylate-based resin and reshaping the resin.
Further, (A1) a mixed and recovered resin (A) consisting of waste plastic mainly composed of polystyrene resin, (A2) waste plastic mainly composed of ABS resin, and (A3) waste plastic mainly composed of α-olefin resin. 70-9
(B1) 1 to 98% by weight of a polyphenylene ether-based resin, (B2) 1 to 98% by weight of a methyl methacrylate-based resin, and (B3) at least one polymer block of an aromatic vinyl with respect to 9% by weight. Having at least one diene polymer block and an aromatic vinyl content of 5
Resin (B) 1 to 30 consisting of 1 to 98% by weight of a hydrogenated product of a block copolymer in an amount of from 95% by weight to 95% by weight
It is a method of recycling waste plastics, which comprises mixing and reforming by weight.

Hereinafter, the present invention will be described in more detail. As the polystyrene resin used in the present invention, those generally used for molding, such as styrene homopolymer (PS), high impact polystyrene (HIPS), and methyl methacrylate-styrene copolymer (MS) , Methyl methacrylate-butadiene-styrene copolymer (MBS), styrene-maleic anhydride copolymer (SMA), styrene-methacrylic acid copolymer (SMAA), and α-methylstyrene or maleimide. Heat-resistant styrene resin.

The ABS resin used in the present invention includes:
Styrene-acrylonitrile copolymer (AS), styrene-acrylonitrile-acryl rubber copolymer (AA
S), styrene-acrylonitrile-chlorinated polyethylene copolymer (ACS), styrene-acrylonitrile-
Heat resistance obtained by copolymerizing ethylene-propylene rubber copolymer (AES), acrylonitrile-styrene-ethylene-vinyl acetate copolymer, styrene-acrylonitrile-butyl acrylate copolymer (BAAS), α-methylstyrene or maleimide Including ABS resin, etc.
Examples of the α-methylstyrene-acrylonitrile copolymer resin include an α-methylstyrene-acrylonitrile copolymer resin in which the styrene portion of the styrene-acrylonitrile copolymer resin is replaced with α-methylstyrene.

The α-olefin resin in the present invention is a homopolymer obtained by copolymerizing an α-olefin homopolymer containing ethylene or an α-olefin containing ethylene with an unsaturated acid or unsaturated ester. Any copolymer may be used as long as it is a copolymer in which the amount of α-olefin containing ethylene exceeds 50% by weight. Α- containing preferably ethylene
The olefin is at least 70% by weight. Specific examples of the α-olefin include ethylene, propylene, butene-1, pentene-1, octene-1, decene-1, 4-methyl-
Pentene-1, 3-methyl-butene-1 and the like. Of course, other monomers may be used as long as they are α-olefins.

The polyphenylene ether of the present invention is
(Hereinafter simply abbreviated as PPE) is a bonding unit:

[0011]

Embedded image

(Wherein R1, R2, R3 and R4 are each selected from the group consisting of hydrogen, halogen, hydrocarbon and substituted hydrocarbon groups, and may be the same or different from each other. ), And the reduced viscosity (0.
5 g / dl, chloroform solution, measured at 30 ° C.)
It is in the range of 15-0.70, more preferably 0.2-0.
A homopolymer and / or copolymer in the range of 66. As a specific example of this PPE, poly (2,6)
-Dimethyl-1,4-phenylene ether), 2,6-
Copolymers of dimethylphenol and 2,3,6-trimethylphenol are preferred, and among them, poly (2,6
-Dimethyl-1,4-phenylene ether) is preferred.

The method for producing such a PPE is not particularly limited as long as it can be obtained by a known method. For example, Ha described in US Pat.
Y can be easily prepared by oxidative polymerization of 2,6-xylenol using a complex of a cuprous salt and an amine as a catalyst.
No. 306875, U.S. Pat. No. 3,257,357, U.S. Pat. No. 3,257,358, Japanese Patent Publication No. 52-17880, Japanese Patent Publication No. 50-51197.
Can be easily manufactured by the method described in Japanese Patent Application Publication No.

The PPE used in the present invention may be prepared by melting the above-mentioned PPE and an α, β-unsaturated carboxylic acid or a derivative thereof in a molten state in the presence or absence of a radical generator in addition to the above-mentioned PPE. 80 to 350 in slurry and state
Modified (0.01 to 10% by weight grafted or added) PPE obtained by reacting at a temperature of 0 ° C.
And the above-mentioned PPE and the modified PPE
May be a mixture in any ratio. Also, P
As a PE, a phosphorus compound-treated PPE obtained by adding 0.2 to 5 parts by weight of 9,10-dihydro-9-oxa-10-phosphaphenanthrene with respect to 100 parts by weight of the PPE and melt-kneading the PE can also be provided.

The PPE used in the present invention is the above-mentioned PPE.
In addition to PE, those obtained by adding polystyrene or impact-resistant polystyrene to these PPEs in an amount not exceeding 90% by weight can be suitably used. In the present invention, the conjugated diene polymer refers to a polymer obtained by polymerizing a conjugated diene alone or one or more monomers copolymerizable with the conjugated diene by a conventionally known method. Specific examples of these conjugated dienes include butadiene, isoprene, chloroprene, and the like. Other monomers may be used as long as the monomer has a conjugated diene structure.

The polymer of the conjugated diene in the present invention may have any molecular weight as long as it is obtained by polymerizing a conjugated diene monomer. Preferably 10,000 or more 2
000000 or less. If the molecular weight is less than 10,000, the impact resistance of the (co) polymer modified with the conjugated diene polymer is not improved, and it is not preferable. If it exceeds 2,000,000, the impact resistance of the (co) polymer modified with the conjugated diene rubber is increased. The properties are not improved and are not preferred. A more preferred range of the molecular weight is from 20,000 to 500,000. The molecular weight can be measured by a conventionally known evaluation method. Specifically, gel permeation chromatography (GP
C) method, light scattering method, osmotic pressure method, solution viscosity method and the like. Of course, other methods may be used.

Specific examples of these conjugated diene polymers include polybutadiene, poly (styrene-butadiene),
Diene rubbers such as poly (acrylonitrile-butadiene), isoprene rubber, chloroprene rubber, and ethylene-propylene-diene monomer terpolymer (EPD)
M) and the like. The polymer of the conjugated diene in the present invention may be one in which the double bond in the diene copolymer is hydrogenated depending on the use.
Further, the ratio of hydrogenation of the double bond in the diene copolymer may be any.

The method of hydrogenation includes known methods, for example, the methods described in JP-B-42-8704 and JP-B-1-37970. The methyl methacrylate polymer in the present invention is a homopolymer or a copolymer obtained by homopolymerizing or copolymerizing a monomer component containing methyl methacrylate as a main component.

The monomer component used in the present invention comprises a monomer containing a methyl methacrylate monomer and other copolymerizable monomers. Other copolymerizable monomers include, for example, α, β-unsaturated carboxylic acid alkyl esters,
α, β-unsaturated carboxylic acids, aromatic vinyl, vinyl cyanide, N-substituted maleimides, maleic anhydride and the like can be used as needed. Further, it may contain the conjugated diene polymer described above. Among these, α,
β-unsaturated carboxylic acid alkyl esters are preferred. These may be used as a mixture. Examples of the α, β-unsaturated carboxylic acid alkyl ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, glycidyl acrylate, cyclohexyl acrylate, acrylic Examples thereof include phenyl acrylate, benzyl acrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, glycidyl methacrylate, cyclohexyl methacrylate, butyl cyclohexyl methacrylate, phenyl methacrylate, and benzyl methacrylate. Among these, methyl acrylate,
Ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and butylcyclohexyl methacrylate are preferred. Examples of the α, β-unsaturated carboxylic acid include acrylic acid and methacrylic acid. Examples of the aromatic vinyl include styrene and α-
Methyl styrene, halogenated styrene, alkylated styrene, vinyl naphthalene and the like can be mentioned. Examples of vinyl cyanide include acrylonitrile and methacrylonitrile. Examples of the N-substituted maleimides include maleimide, N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide and the like.

As a method for producing such a methyl methacrylate polymer, a known polymerization method can be employed. For example, bulk polymerization,
Examples include methods such as suspension polymerization, bulk-suspension polymerization, solution polymerization or emulsion polymerization. Examples of such polymers include PMMA resins. The block copolymer in the present invention has a polymer structure represented by the following formula. That is, (AB) n, (AB) n-A, B- (AB)
n, [(AB) n] m + 1-X, [(AB) n-A]
m + 1-X, [(BA) n] m + 1-X, [(BA) n
-B] m + 1 -X.

In the above formula, A is an aromatic vinyl polymer block, and B is a hydrogenated product of a polymer block of a conjugated diene compound. The number average molecular weights of the copolymer blocks A and B are 3000 to 500000, respectively. n
Is an integer of 1 to 5, preferably 1 to 3, m is an integer of 1 to 10, preferably 1 to 5, and X represents a residue of a coupling agent or a residue of a polyfunctional organolithium compound. In the block copolymer of the present invention, the copolymer block A
And B have a number average molecular weight of 3000 to 500, respectively.
000, preferably 5,000 to 300,000, more preferably 10,000 to 200,000. The number average molecular weight of the block copolymer as a whole is 10,000.
１０００1,000,000, preferably 20,000 to 80,000
0. If the number average molecular weight of the block copolymer as a whole is less than 10,000, the strength is poor, and
If it exceeds, impact resistance is poor.

The 1,4,1,2 and 3,4 structures in the polymer may be in the form of block, random or taper, respectively. Preferably, it is a block body. It is essential that the conjugated diene portion is hydrogenated. In the present invention, 8 of the double bond in the conjugated diene polymer is used.
The one in which 0% or more is hydrogenated is used. Preferably, 90% or more of the double bonds in the conjugated diene polymer are hydrogenated. If the hydrogenation rate is less than 80%,
Poor weather resistance.

As the method for producing the block copolymer of the present invention, the method for producing a block copolymer comprising aromatic vinyl and a conjugated diene can be applied mutatis mutandis. Such methods include:
For example, JP-B-36-19286, JP-B-43-179
No. 79, JP-B-45-31951, JP-B-46-32
No. 415, JP-B-48-2423, JP-B-48-41
06, JP-B-49-36947, JP-B-51-49
No. 567, No. 56-28925, No. 3-64
No. 526 and Japanese Patent Publication No. 3-64527. These use a polymerization initiator such as an organic alkali metal compound in a hydrocarbon solvent, and as a vinylating agent, an ether compound such as diethyl ether or tetrahydrofuran, triethylamine, N, N, N ', N',-.
A method of block copolymerizing aromatic vinyl and a conjugated diene compound using a tertiary amine such as tetramethylethylenediamine, an epoxidized soybean oil as a coupling agent if necessary, and a polyfunctional compound such as silicon tetrachloride, It is obtained as a polymer having a linear, branched, or radial structure.

The method for hydrogenation includes known methods, for example, the methods described in JP-B-42-8704 and JP-B-1-37970. In the present invention, the ratio of the waste plastic mixed and recovered resin (A) is 70 to 99% by weight.
And the proportion of the mixed resin (B) is in the range of 1 to 30% by weight. This ratio is determined according to the required mechanical strength and moldability. Preferably (A) is 75
And (B) is in the range of 5 to 25% by weight.

In claim 1 of the present invention, the proportions of (B1) and (B2) represented by (B1) polyphenylene ether and (B2) methyl methacrylate polymer are both 1 to 99.
% By weight. This ratio is determined according to the required mechanical strength and moldability. Preferably (B
Both (1) and (B2) are in the range of 10 to 90% by weight, and more preferably both (B1) and (B2) are in the range of 20 to 80% by weight. In claim 2 of the present invention, (B1) represented by (B1) a polyphenylene ether, (B2) a methyl methacrylate polymer, and (B3) a block polymer.
The proportions of (B2) and (B3) are both in the range of 1 to 98% by weight. This ratio is determined according to the required mechanical strength and moldability. Preferably (B1), (B
2) and (B3) are each in the range of 10 to 80% by weight, and more preferably 15 (B1), (B2) and (B3).
７０70% by weight.

In the present invention, when the component (B) is mixed with the component (A), it is possible to add an inorganic filler, an organic filler and a plasticizer to such an extent that the characteristics thereof are not impaired. Examples of the inorganic filler used here include calcium carbonate, magnesium carbonate, silica, calcium silicate, carbon black, carbon fiber, glass fiber, metal fiber, titanium oxide, clay, mica, talc, magnesium hydroxide, and aluminum hydroxide. , Zinc oxide and the like. Furthermore, examples of the organic filler include various organic fibers, wood flour, walnut shell flour, jute, kenaf, cellulose, lignin and the like. Examples of the plasticizer include phthalic acid esters such as polyethylene glycol and dioctyl phthalate (DOP). In addition, other additives, for example, lubricants, organic and inorganic pigments, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, flame retardants, silicone oil, anti-blocking agents,
Blowing agents, antistatic agents, antibacterial agents and the like are also preferably used.

As the method for mixing the components (A) and (B) in the present invention, any melt-kneading machine used in the production of ordinary resins and the like can be used. Specifically, there are a batch-type kneader such as a mixing roll, a Banbury mixer, and a pressure kneader, and a continuous-type kneader such as a single-screw extruder and a twin-screw extruder. Further, a high-speed rotary impact friction type mixing and melting machine such as a K mixing machine can also be used. The kneading order is not limited. For example, the component (A) and the component (B) may be kneaded at once, or the component (B) may be kneaded in advance, and the obtained product may be mixed with the component (A). It may be kneaded.

For the molding of the present invention, known methods generally used for molding a thermoplastic resin, for example, injection molding, extrusion molding, blow molding, inflation molding, vacuum molding, press molding and the like are used. It is molded into various molded articles. Further, after being formed into a film, a biaxially stretched film, a sheet, a foamed sheet, a foamed bead, or the like, it can be further molded into a desired molded body. Furthermore, a molded article can be obtained immediately after melt-kneading the components (A) and (B) in the molding machine without using a melt-kneading machine. In this case, the component (B) may be melt-kneaded in advance.

Various resin molded articles can be obtained by the recycling method of the present invention. For example, TV parts, telephone parts, OA equipment parts, vacuum cleaner parts, electric fan parts, air conditioner parts, refrigerator parts, washing machine parts, humidifier parts, dish dryer parts, etc. It can be used for a wide range of applications such as various OA equipment and home appliances, various sanitary articles such as toilet seats and wash basin parts, and other building materials, vehicle parts, daily necessities, toys, and miscellaneous goods.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. However, the present invention is not limited to these examples. The materials used in Examples and Comparative Examples in the present invention are as shown below. (1) Waste plastic mainly composed of polystyrene resin A pellet obtained by crushing the resin portion of a waste TV manufactured by Company A is used. The pellets contain 93% by weight of high impact polystyrene. Note that PS is described in Table 1 of Examples and Comparative Examples of the present invention.

(2) Waste plastic mainly composed of ABS resin A pellet obtained by crushing the resin portion of a waste fax manufactured by Company B is used. The pellets contain 88% by weight of ABS resin. Note that ABS is described in Table 1 of Examples of the present invention and Comparative Examples. (3) Waste plastic mainly composed of α-olefin resin A pellet obtained by crushing the resin portion of a washing machine manufactured by Company C is used.
The content of the polypropylene resin in the above plastic was 75%. In addition, in Example 1 of this invention and Table 1 of a comparative example, it describes as PP.

(4) Polyphenylene ether Zylon 100V manufactured by Asahi Kasei Corporation is used. In addition, it describes as PPE in Table 1 of the Example of this invention and a comparative example. (5) Methacrylic ester-based copolymer Delpet 60N manufactured by Asahi Kasei Corporation is used. In addition, in Table 1 of the Example of this invention and a comparative example, it describes as PMMA. (6) Hydrogenated product of block copolymer Tuftec H1052 manufactured by Asahi Kasei Corporation is used.
In addition, in Table 1 of the Example of this invention, it describes as SEBS. The evaluation methods used in Examples and Comparative Examples in the present invention are as shown below.

Drop strength Air-conditioner housing molded product molded at a cylinder temperature of 240 ° C.
(A molded article weight of 5.3 kg) is dropped on a concrete floor from a height of 1.5 m, and the occurrence of cracks and the like is visually evaluated. The evaluation criteria are as follows. ：: No cracks, cracks, etc. occurred. X: Cracks, cracks, etc. are remarkable. Peeling A 15 mm long cut is made with a nipper in a 2 mm thick sheet injection-molded at a cylinder temperature of 240 ° C., and one of the cuts is bent 180 °, and a bent and cracked portion is visually observed.
The evaluation criteria are as follows. ：: No peeling occurred. X: The peeling has occurred remarkably.

[0034]

Examples 1 to 3 and Comparative Examples 1 and 2 Resins were mixed according to the formulations shown in Table 1 of Examples and Comparative Examples of the present invention, and the mixture was mixed with a twin screw extruder PCM-30 manufactured by Ikegai Iron Works Co., Ltd. Barrel temperature 24
The composition was obtained at 0 ° C., 200 revolutions per minute, and an extrusion speed of 15 kg per minute. The obtained composition was subjected to injection molding at a cylinder temperature of 240 ° C., and the items described in Table 1 were evaluated. The results obtained are shown in Table 1.

[0035]

[Table 1]

[0036]

According to the present invention, a molded article that can withstand reuse can be obtained from the discarded plastic, and the discarded plastic can be effectively recycled.

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Claims (3)

[Claims] 1. A mixed and recovered resin (A) 70 to 9 comprising (A1) a waste plastic mainly composed of a polystyrene resin and (A2) a waste plastic mainly composed of an ABS resin.
Resin (B) 1 to 30 comprising (B1) 1 to 99% by weight of polyphenylene ether resin and (B2) 1 to 99% by weight of methyl methacrylate resin based on 9% by weight.
A method for recycling waste plastics, comprising mixing and re-molding by weight%. 2. A mixed and recovered resin comprising (A1) a waste plastic mainly composed of a polystyrene resin, (A2) a waste plastic mainly composed of an ABS resin, and (A3) a waste plastic mainly composed of an α-olefin resin. (A)
(B1) 1 to 98% by weight of polyphenylene ether-based resin, (B2) 1 to 98% by weight of methyl methacrylate-based resin, and (B3) at least one polymer block of aromatic vinyl based on 70 to 99% by weight. (B) a resin having at least one polymer block of styrene and conjugated diene, and 1 to 98% by weight of a hydrogenated block copolymer having an aromatic vinyl content of 5% by weight or more and 95% by weight or less.
A method for recycling waste plastic, comprising mixing 1 to 30% by weight and reshaping. 3. A molded article formed by the method according to claim 1.