JP3133178B2 - Method for reusing molded articles made of painted polyolefin resin composition - 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 reusing a molded article made of a painted polyolefin resin composition.

[0002]

2. Description of the Related Art Polyolefin-based resin compositions are widely used in machine parts, automobile parts, household goods, various containers and the like because of their excellent mechanical strength, chemical resistance and moldability. In particular, automobiles are used in various parts, but their use as bumper materials has been expanding in recent years.

[0003] Automotive bumpers are often painted,
Further, the adhesion between the coating film and the bumper resin is so strong that it cannot be easily peeled off. Therefore, it is difficult to peel off the coated film of the polyolefin resin composition, which is represented by these automobile bumpers, and to reuse it, and in many cases, it is incinerated or disposed of.

[0004] Further, with the recent advance in technology, a method for removing the coating with a solvent or the like is being developed. However, this method has problems in safety, environment and the like, and many methods are required for industrial use. There are issues left. In addition, a method of pulverizing a molded product of the coated polyolefin-based resin composition, melting it with an extruder, and removing the coating film with a screen can be considered. In this method, a finely pulverized coating film forms a screen. It escapes and mixes into granulated pellets. If the pellets containing these coatings are to be reused, the impact strength, tensile elongation, etc., become extremely low, and the value is low as an industrial member.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for effectively reusing a molded article of a coated polyolefin resin composition.

[0006]

That is, in the present invention, when a molded article made of a coated polyolefin resin composition is reused, the polyolefin resin composition 1
(A) a modified elastomer to which a molecular unit containing a carboxylic acid group or a derivative thereof is bonded and (b) a thermoplastic polyurethane elastomer to one part of (a)
/ 2 parts by weight or less A total of 1 to 40 parts by weight of a molded article made of a coated polyolefin-based resin composition, wherein the molded article is reused.

Hereinafter, the present invention will be described in detail. Examples of the coated polyolefin resin composition used in the present invention include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, poly-4-methylpentene-1, polypropylene, Examples thereof include polybutene, propylene-ethylene rubber, and ethylene-butene rubber, and one or a mixture of two or more of these can be used. Further, the recovered polyolefin-based resin composition may contain a filler such as talc or barium sulfate. In particular, automobile bumper materials mainly composed of polypropylene and mixed with propylene-ethylene rubber or the like have a large production volume, and the necessity for industrial recycling is high.

There are no particular restrictions on the coating, but acrylic or vinyl-modified acrylic resin coatings, alkyd resin coatings, polyurethane resin coatings,
Painted with an epoxy resin-based paint, an epoxy-polyamide resin-based paint, a phenolic resin-based paint, a melamine resin-based paint, a urea resin-based paint, and the like.
Also, a primer may be used for painting,
Known primers such as chlorinated polyethylene, chlorinated polypropylene, chlorinated rubber, cyclized rubber, ethylene vinyl acetate copolymer, aromatic petroleum resin, and coumarone-indene resin can be used.

The molded product of the polyolefin resin composition is conveniently ground for reuse. The crusher is not particularly limited, but it is necessary that the crusher can be passed through an extruder as a crushed product, and examples thereof include a cutter crusher and a hammer crusher. A feature of the present invention is that when the pulverized product is melted, it is mixed with a modified elastomer to which a molecular unit containing a carboxylic acid group or a derivative thereof is bonded.

The modified elastomer (a) used in the present invention includes (1) a styrene-based elastomer,
(2) Those obtained by modifying an olefin elastomer with an unsaturated carboxylic acid or a derivative thereof. (1) Examples of the styrene-based elastomer include a vinyl aromatic-conjugated diene block copolymer, a vinyl aromatic-conjugated diene random copolymer, and hydrogenated products thereof. Particularly, those obtained by hydrogenating a vinyl aromatic-conjugated diene block copolymer are preferable.

The hydrogenated block copolymer used in the present invention is a block A mainly composed of a vinyl aromatic compound.
And a polymer B mainly composed of an olefin compound hydrogenated to such an extent that the degree of unsaturation of the conjugated diene compound portion does not exceed 20%. The polymer block A mainly composed of a vinyl aromatic compound has a weight ratio of the vinyl aromatic compound to the conjugated diene compound of 100/0 to 51/49, preferably 100/0 to 70/30. When a vinyl aromatic compound and a conjugated diene compound are copolymerized as a united block, the distribution of the conjugated diene compound in this block may be random, tapered (a monomer component increases or decreases along the molecular chain), or partially. It may be in the form of a block or any combination of these.

In the polymer block B mainly composed of a conjugated diene compound, the weight ratio of the vinyl aromatic compound to the conjugated diene compound is 0/100 to 49/51, preferably 0.
/ 100 to 30/70 is a polymer block, and when a conjugated diene compound and a vinyl aromatic compound are copolymerized, the distribution of the vinyl aromatic compound in this block is random, tapered (along the molecular chain). The monomer component may be increased or decreased), partially block-like, or any combination thereof. Examples of the vinyl aromatic compound used here include one or more of styrene, α-methylstyrene, alkylstyrene such as p-methylstyrene and p-tert-butylstyrene, paramethoxystyrene, and vinylnaphthalene. Among them, styrene and p-methylstyrene are particularly preferable. As the conjugated diene compound, butadiene, isoprene, piperylene, methylpentadiene, phenylbutadiene, 3,4-dimethyl-
One or more kinds are selected from 1,3-hexadiene, 4,5-diethyl-1,3-octadiene and the like,
Among them, butadiene and / or isoprene are particularly preferred.

The content of the vinyl aromatic compound is 10 to 6
The content of 0% by weight is preferable, and if it exceeds 60% by weight, the resin itself becomes resinous, and the impact resistance of the recycled product becomes low. The molecular structure of the block copolymer may be linear, branched, radial, or a combination thereof. Each of the polymer block mainly composed of a vinyl aromatic compound and the block mainly composed of a conjugated diene may have the same structure, the monomer component content, their distribution in the molecular chain, the molecular weight of the block. Each structure such as a micro structure may be different.

As a method for producing the block copolymer, for example, JP-B-36-19286 and JP-B-43-149
79 and JP-B-49-36957. These use an organic lithium compound or the like as an anionic polymerization initiator in a hydrocarbon solvent, and an ether compound such as diethyl ether or tetrahydrofuran as a vinylating agent, triethylamine, N,
A tertiary amine such as N, N ', N'-tetramethylethylenediamine, and, if necessary, a polyfunctional compound such as epoxidized soybean oil and silicon tetrachloride as a coupling agent, and a vinyl aromatic compound and a conjugated diene compound. Is a block copolymer having a linear, branched or radial structure. In the present invention, those obtained by any polymerization method can be used as long as they are those described above.

The above block copolymer is prepared by a known method,
For example, a hydrogenated block copolymer can be obtained by hydrogenation according to the method described in JP-B-42-8704. In the present invention, it is preferable to hydrogenate at least 80% of the conjugated diene portion. The higher the rate of hydrogenation, the better the compatibility with the polyolefin-based resin composition and the less likely it is to undergo thermal degradation, so that an excellent recycled product can be obtained. The hydrogenation rate can be analyzed by instrumental analysis using a nuclear magnetic resonance apparatus (NMR).

(2) The olefin elastomer is a copolymer rubber of two or more α-olefins such as ethylene, propylene, 1-butene, 1-hexene and 4-methyl-pentene. Specific examples include ethylene-propylene copolymer rubber (EPR), ethylene-butene copolymer rubber (EBR), ethylene-propylene-diene copolymer rubber (EPDM), and the like.

The above elastomer is then modified by an addition reaction with at least one modifier selected from unsaturated carboxylic acids and derivatives thereof, whereby the modified elastomer used in the present invention is synthesized. Examples of the unsaturated carboxylic acids and derivatives thereof as modifiers include maleic acid, maleic anhydride, maleic ester, maleic amide, maleic imide, fumaric acid, fumaric ester, fumaric amide, fumaric imide, itacone Acid, itaconic anhydride, itaconic acid ester, itaconic amide, itaconic imide, halogenated maleic acid, maleic anhydride, halogenated maleic ester, halogenated maleic amide, halogenated maleimide, cis-
4-cyclohexene-1,2-dicarboxylic acid, cis-4-cyclohexene-1,2-dicarboxylic acid, cis-
4-cyclohexene-1,2-dicarboxylic acid ester,
Cis-4-cyclohexene-1,2-dicarboxylic acid amide, cis-4-cyclohexene-1,2-dicarboxylic imide, endo-cis-bicyclo (2,2,1) -5-
Heptene-2,3-dicarboxylic acid, endo-cis-anhydride
Bicyclo (2,2,1) -5-heptene-2,3-dicarboxylic acid, endo-cis-bicyclo (2,2,1) -5
-Heptene-2,3-dicarboxylic acid ester, endo-
Cis-bicyclo (2,2,1) -5-heptene-2,3
-Dicarboxylic amides, endo-cis-bicyclo (2,
2,1) -5-heptene-2,3-dicarboxylic imide, acrylic acid, acrylic ester, acrylic amide, methacrylic acid, methacrylic ester, methacrylamide, and the like. These are not only one kind, but two
Even a mixture of more than two kinds can be used. Of these, unsaturated dicarboxylic acids or derivatives thereof are preferred, and maleic anhydride is particularly preferred.

The modified elastomer can be obtained by adding the above modifier to the base elastomer in a solution state or a molten state with or without the use of a radical initiator. The method for producing these modified elastomers is not particularly limited in the present invention, but the obtained modified elastomer contains an undesired component such as a gel, or its melt viscosity is remarkably increased to deteriorate processability. The manufacturing method is not preferred. Preferred methods include, for example, in an extruder, in the presence of a radical initiator,
A method of reacting the base elastomer with the above modifier is exemplified.

The amount of the molecular unit containing a carboxylic acid group or a derivative thereof contained in the modified elastomer, that is, the addition amount of the unsaturated carboxylic acid or the derivative thereof, is defined as an average value of the entire modified elastomer used in the present invention. It is 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, per 100 parts by weight of the elastomer. When the molecular unit containing a carboxylic acid group or a derivative group thereof is 0.0
If the amount is less than 5 parts by weight, almost no improvement effect is recognized as compared with the unmodified elastomer, and if it exceeds 10 parts by weight, the improvement effect is not remarkable as compared with the case of less than 10 parts by weight.

The content of the molecular unit containing a carboxylic acid group or a derivative thereof in the modified elastomer can be easily determined by a method such as an infrared spectrophotometer or titration. Further, in the present invention, an unmodified elastomer may be contained within a range in which the added amount of the unsaturated carboxylic acid or its derivative in the modified elastomer used satisfies the above range as the average value of the whole.

In the present invention, (a) the modified elastomer can be used together with (b) the thermoplastic polyurethane elastomer. The thermoplastic polyurethane elastomer is obtained by addition polymerization of a long-chain glycol and a short-chain glycol having active hydrogens at both terminals using a diisocyanate compound. There are no particular restrictions on the compound used, but typical long-chain glycols include polyesters, polyethers, and polycarbonates. If a specific compound name is given, in the case of polyester, dehydration condensates of adipic acid and various glycols, such as poly (ethylene adipate), poly (diethylene adipate), poly (1,4-butylene adipate), and poly (1 , 6-hexane adipate), and polycaprolactone can also be used. Examples of the polyether type include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (propylene glycol / ethylene glycol) and the like, and examples of the polycarbonate type include poly (1,6-hexamethylene glycol carbonate).

Polyolefin glycols are also useful, and polybutadiene diol, polyisoprene diol and hydrogenated products thereof can be preferably used. Representative examples of the shortened glycol include aliphatic glycols and aromatic glycols. Specific examples of the compound name include ethylene glycol, 1,3-propylene glycol, and 1,4-propylene glycol. Examples thereof include butane glycol, 1,3-butane glycol, 1,5-pentane glycol, 1,6-hexane glycol and the like. Examples of the aromatic glycol system include bisphenol A, hydroquinone diethylol ether, bisphenol A / ethylene glycol and the like. Can be illustrated.

Examples of the diisocyanate include aromatic, alicyclic and aliphatic diisocyanates, such as tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, and the like. Examples thereof include isophorone diisocyanate and the like, and further include xylylene diisocyanate and hydrogenated 4,4'-diphenylmethane diisocyanate.

The thermoplastic polyurethane elastomer is classified into a complete thermoplastic type and an incomplete thermoplastic type according to its synthesis conditions. These are the OH groups of the bifunctional long- and short-chain glycols of the starting material and the N and
Determined by the molar ratio of CO groups, about 0.95 <NCO / OH
≦ 1 is a completely thermoplastic type, and about 1 <NC
The incomplete thermoplastic type was synthesized with O / OH <1.1. Either one can be used in the present invention. (B) The amount of the thermoplastic polyurethane elastomer is:
(A) It can be used in 以下 or less of the modified elastomer. Even if it exceeds 1/2, the characteristics of the recycled product do not improve,
Further, the cost is undesirably increased.

The amount of the modified elastomer and the amount of the thermoplastic polyurethane elastomer added to the pulverized product of the polyolefin resin composition are 1 to 100 parts by weight of the pulverized product.
If the amount is 40 parts by weight, preferably 5 to 30 parts by weight, and less than 1% by weight, the impact strength and tensile elongation of the obtained regenerated product are low, and the object of the present invention cannot be achieved. On the other hand, if it exceeds 40 parts by weight, the obtained recycled product has low rigidity, and the cost is undesirably high. Examples of the melt mixing device used in the present invention include an extruder, a mixing roll, a kneader, and the like. In the present invention, a melt mixing method using an extruder is particularly preferable.

In addition, it is possible to add a reinforcing agent or a filler such as calcium carbonate, talc, silica, carbon black, glass fiber, clay or the like to the extent that the properties are not impaired. Further, other additives such as a heat stabilizer, an antioxidant, an ultraviolet absorber, a colorant, and a pigment may be added.

[0027]

EXAMPLES The present invention will now be described more specifically and in detail with reference to the following Examples, which should not be construed as limiting the invention thereto. The measurement standards and test methods of the physical properties shown in Examples and Comparative Examples are as follows. -Izod impact strength (with kg / cm / cm notch) Measured at -30 ° C according to JIS-K7110. -Tensile elongation <Elongation at break (%)> Measured at 23 ° C according to JIS-K7113. -Flexural modulus (kg / cm ² ) Measured at 23 ° C according to JIS-K7203.

The following materials were used as raw materials in the examples and comparative examples. <Polyolefin resin composition> Polypropylene (M8
619: 80 parts by weight of ethylene-propylene rubber (EP02P: manufactured by Nippon Synthetic Rubber Co., Ltd.) 20
The weight part is twin screw extruder (30mmφ, L / D: 28)
The mixture was melt-kneaded at 220 ° C. and 60 rpm to form pellets.

The obtained pellets were injection-molded at 230 ° C. to prepare test pieces (tank pieces and dumbbell pieces), and the Izod impact strength, tensile elongation and flexural modulus were measured. (Reference example: reference physical properties) Further, the obtained dumbbell piece was subjected to the following coating to obtain a molded article of the coated polyolefin resin composition.
This was pulverized by a pulverizer and used in the following Examples. (Painting method) Primer coating (pretreatment) ── primer (S-1
12: Brushed with Nagashima Special Paint Co., Ltd.)
Dry for 5 minutes. 2. Coating of paint: Polyurethane-based paint (Suncoat Glaze V: manufactured by Nagashima Special Paint Co., Ltd.) and dried. <Various elastomers> (1) Styrene block copolymer Tufprene A (Asahi Kasei Co., Ltd.) ) <Styrene-based elastomer having a styrene content of 40% by weight> (2) Hydrogenated block copolymer-1 Tuftec H1052 (manufactured by Asahi Kasei Corporation) <Saturated styrene-based elastomer having a styrene content of 20% by weight> (3) Hydrogenation Block copolymer-2 Tuftec H1051 (manufactured by Asahi Kasei Corporation) <Saturated styrenic elastomer having a styrene content of 40% by weight> (4) Modified hydrogenated block copolymer-1 Tuftec H1052 modified with maleic anhydride Having a maleic anhydride content of 0.4% by weight (5) Modified hydrogenated block copolymer-2 Tuftec 1051 modified with maleic anhydride and having a maleic anhydride content of 1.5% by weight (6) Modified hydrogenated block copolymer composition-1 20% by weight of Pandex T-5000V (manufactured by Dainippon Ink and Chemicals, Inc.) <thermoplastic polyurethane elastomer> was melt-kneaded with a twin-screw extruder to obtain pellets. Polymer composition-2 60% by weight of the modified hydrogenated block copolymer-2 and 40% by weight of Pandex T-5880M (manufactured by Dainippon Ink and Chemicals, Inc.) <thermoplastic polyurethane elastomer> in a twin-screw extruder. (8) Olefin copolymer-1 JSR EP 02P (manufactured by Nippon Synthetic Rubber Co., Ltd.) <Ethylene-propylene copolymer rubber> (9) Olefin copolymer Copolymer-2 Toughmer P-0280 (manufactured by Mitsui Petrochemical Co., Ltd.) <Ethylene-α-olefin copolymerized elastomer> (10) Modified olefin-based copolymer Tuffmer P-0280 modified with maleic anhydride With a maleic anhydride content of 0.4% by weight.

[0030]

Example 1 10 parts by weight of a modified hydrogenated block copolymer-1 and 10 parts by weight of Irganox 1076 per 100 parts by weight of a pulverized product of a molded product (painted) of a polyolefin resin composition
0.2 parts by weight (manufactured by Ciba Geigy Co., Ltd.) were mixed, and the mixture was mixed with a twin-screw extruder (30 mmφ, L / D: 33.5) to 220
The resulting mixture was melt-kneaded at 100 ° C. and pelletized.

The obtained pellet was injection molded at 230 ° C. to prepare a test piece, and the Izod impact strength, tensile elongation and flexural modulus were measured. The results are shown in Table 1.

[0032]

Examples 2 to 6 In the same manner as in Example 1, various elastomers were melt-kneaded at the ratios shown in Table 1, pelletized, molded and measured for physical properties. The results are shown in Table 1, and it can be seen that the regenerated product also has excellent impact strength and tensile elongation.

The excellent properties of the reclaimed product obtained by the method of the present invention are clear from the following comparative examples.

[0034]

Comparative Example 1 A pulverized product of a molded product (painted) of a polyolefin resin composition was directly re-pelleted, and the physical properties were measured. The physical properties are extremely reduced.

[0035]

Comparative Examples 2 to 8 In the same manner as in Example 1, various elastomers having structures different from the present invention were kneaded at the ratios shown in Table 2.
Physical properties were measured. It has low impact strength and tensile elongation, and is difficult to reuse.

[0036]

[Comparative Example 9] An example in which the amount of the added elastomer is large,
Low flexural modulus, not practical. The results of Comparative Examples 1 to 9 are shown in the table.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

According to the present invention, there is provided a method for effectively reusing a coated polyolefin resin composition which has been discarded in the past, which is effective for effective use of resources and environmental protection. The regenerated product obtained by the method of the present invention has excellent physical properties and can be recycled.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-4228 (JP, A) JP-A-5-154861 (JP, A) JP-A-5-92430 (JP, A) 169479 (JP, A) JP-A-5-337942 (JP, A) JP-A-5-200749 (JP, A) JP-A-7-68551 (JP, A) JP-A-6-23748 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29B 17/00-17/02 C08J 11/00-11/28

Claims (2)

(57) [Claims] When reusing a molded article made of a coated polyolefin resin composition, a molecular unit containing (a) a carboxylic acid group or a derivative thereof is added to 100 parts by weight of the polyolefin resin composition. A modified polyolefin-based resin composition characterized by mixing and melting a modified elastomer to which is bonded and (b) a thermoplastic polyurethane elastomer in a total amount of 1 to 40 parts by weight which is not more than 1/2 of (a). How to reuse molded articles. 2. The modified elastomer (a) according to claim 1, wherein the degree of unsaturation of at least one vinyl aromatic compound polymer block A and a conjugated diene compound portion does not exceed 20%. A carboxylic acid group or a derivative thereof in a block copolymer comprising at least one olefin compound and a vinyl aromatic compound content of 10 to 60% by weight. 2. The coated polyolefin resin composition according to claim 1, wherein the modified block copolymer has a molecular unit of 0.05 to 10 parts by weight bonded to 100 parts by weight of the block copolymer. Method for reusing molded objects made of products.