JPH05337942A - Reprocessing method of polypropylene composite material with thermosetting resin coating film - Google Patents

Abstract

(57) [Abstract] [Purpose] In a method of regenerating a polypropylene composite material with a thermosetting resin coating, it is intended to simplify the regenerating process and reduce the regenerating cost. [Structure] For example, a polypropylene composite material with a polyurethane resin coating film is cut into small pieces using a cutting machine or the like. This fine piece is put into a kneading extruder, melt-kneaded at an extrusion temperature of 200 ° C. or higher, the resin coating film is finely divided by thermal decomposition and uniformly dispersed, and then the melt-kneaded product is unsaturated. Add carboxylic acid modified polyolefin and melt knead. Then, the melt-kneaded product is pelletized and collected. [Effect] The processing of this kind of composite material is very simple and the cost of recycling is low, and the pellets obtained by the processing have the original high mechanical properties and appearance of the raw material resin,
There is no problem in recycling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of recycling polypropylene composite material coated with a thermosetting resin, and more specifically, a recycling treatment of waste such as polypropylene bumpers for automobiles coated with polyurethane resin coating. Regarding the method.

[0002]

2. Description of the Related Art In recent years, in terms of waste disposal of plastics, recycling of waste has been required more and more from the viewpoint of effective use of resources and conservation of the global environment. by the way,
Polypropylene composite waste with polyurethane resin coating, for example, recycling of used polypropylene bumpers for automobiles with polyurethane resin coating makes it difficult to completely remove the polyurethane resin coating, resulting in reduced impact properties and appearance. There is a problem of causing defects, and it has been considered difficult to reuse the material for automobile bumpers that require high mechanical properties and high quality appearance.

However, recently, regarding recycling of the above-mentioned automobile bumper, as a method of completely removing the polyurethane resin coating film, a polypropylene automobile bumper with a polyurethane resin coating film was crushed and placed in a reaction tank,
Dip in a film remover consisting of water, alcohol, and organic salt, chemically decompose the polyurethane resin film by reaction decomposition with isocyanate, polyglycol, diamine, etc., and dry it by centrifuge to pellet polypropylene. A method of playing as is proposed.

[0004]

However, this proposed method cannot be said to be industrially advantageous because the recycling process is complicated, waste liquid treatment is required, and the recycling cost is high. An object of the present invention is to solve the above-mentioned conventional problems, and to provide a method for reprocessing a polypropylene composite material with a thermosetting resin coating film, which has a simple recycling process and a low recycling cost. It is in.

[0005]

A method of reprocessing a polypropylene composite material with a thermosetting resin coating film according to the present invention comprises crushing a composite material having a polypropylene layer coated with a thermosetting resin into small pieces. The crushed pieces are put into a kneading extruder and melt-kneaded at a temperature of 200 ° C. or higher, or melt-kneaded in the presence of a coating film decomposition accelerator, and the thermosetting resin coating film is thermally decomposed. After finely divided and uniformly dispersed, after melt-kneading the melt-kneaded product with a specific amount of a polyolefin resin modified by an unsaturated carboxylic acid or a derivative thereof, is blended,
It is characterized by being pelletized and collected.

[0006]

According to the method for regenerating a polypropylene composite material with a thermosetting resin coating of the present invention, a composite material of this type is first crushed into small pieces. Then, the crushed pieces are put into a kneading extruder and melt-kneaded at a temperature of 200 ° C. or higher, or a coating film decomposition accelerator is added and melt-kneaded. Thus, when the fine pieces are melt-kneaded at a temperature of 200 ° C. or higher, the thermosetting resin coating film is finely divided by thermal decomposition and uniformly dispersed. Then, a specific amount of a polyolefin resin modified with an unsaturated carboxylic acid or its derivative is blended with this melt-kneaded product, melt-kneaded, and then pelletized and recovered.

The method for recycling the polypropylene composite material with the thermosetting resin coating film of the present invention will be described in more detail below. The present invention, for example, separates and collects automobile bumper waste made of polypropylene with a polyurethane resin coating,
This is preferably applied when reusing this.

As a bumper for automobiles made of polypropylene, usually, after a primer of a polyurethane resin or an epoxy resin is undercoated on the polypropylene layer in advance,
A method of applying a thermosetting resin, for example, a coating of a polyurethane resin on it is adopted, but for automobiles, which is obtained by directly coating a top coating of a polyurethane resin on a polypropylene layer without undercoating the primer. Bumpers and the like can also be treated by the regeneration treatment method of the present invention.

The polypropylene (referred to as PP) is, for example, an isotactic propylene homopolymer having crystallinity, a copolymerization part composed of an ethylene propylene random copolymer having a small content of ethylene units, or a propylene homopolymer. Substantially crystalline propylene commercially available as a so-called propylene block copolymer, which is composed of a homopolymerized portion composed of a polymer and a copolymerized portion composed of an ethylene-propylene random copolymer having a relatively large content of ethylene units. Block copolymer of ethylene and ethylene, or a substantially crystalline propylene-ethylene in which each homopolymerization part or copolymerization part of this block copolymer is further copolymerized with α-olefin such as butene-1 −
Examples include α-olefin copolymers.

Further, the above PP may be blended with an ethylene copolymer rubber, for example, an ethylene-propylene copolymer rubber or an ethylene-propylene-diene terpolymer as a main component in a small amount. Further, there is no problem even if the polypropylene is blended with an inorganic filler such as talc and calcium carbonate, a pigment such as carbon black, an antioxidant, an ultraviolet absorber and a heat stabilizer.

Therefore, in the method for recycling the polypropylene composite material with the thermosetting resin coating film of the present invention, the waste of the thermosetting resin, for example, the polypropylene composite material with the polyurethane resin coating film is first cut or crushed. Using a machine (crusher), strips, for example, the maximum dimension of 20mm or less,
Preferably at least 50 with a size of 10 mm or less
%, Preferably at least 70%, and the other parts are strips with the longest dimension not exceeding 30 mm.

The strips are placed in a kneading extruder and the extrusion temperature is 200 ° C. or higher, preferably 200 to 300 ° C., more preferably 230 to 270 ° C., and the residence time in the extruder is 15 seconds. Or more, preferably 30 seconds or more,
More preferably, it is melt-kneaded in the range of 30 to 300 seconds so that the polyurethane resin coating film is thermally decomposed into fine particles and uniformly dispersed. In addition, it is also preferable to add a coating film decomposition accelerator when melt-kneading the small pieces. This coating film decomposition accelerator will be described later.

If the extrusion temperature is lower than 200 ° C., the thermal decomposition of the polyurethane resin coating film is insufficient and the coating film cannot be made finer. If it is higher than 300 ° C., the base material polypropylene is thermally denatured (heat deterioration). Then its basic performance is impaired and it cannot be recycled. Further, if the residence time in the extruder is too short, thermal decomposition of the polyurethane resin coating film will be insufficient and the coating film cannot be made finer. Therefore, 15 seconds or more is required in the extrusion temperature range.

As the kneading extruder, both single screw and twin screw can be used. Examples of the coating film decomposition accelerator include Lewis acids such as tin chloride, alkali hydroxides, alkaline earth hydroxides, amines, alcoholates, metal phosphates, alcoholic amines such as diethanolamine, and dibutyltin laurate. It is used alone or in combination of two or more kinds such as organic salts. The amount of the coating film decomposition accelerator added is 0.01 with respect to the polypropylene composite material to be treated.
It is in the range of 1 wt%.

In the present invention, a specific amount of a polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof is blended in the melt-kneaded or melt-kneaded product of the above-mentioned strips, melt-kneaded, and then pelletized and recovered. In the unsaturated carboxylic acid-modified polyolefin resin used in the present invention, examples of the unsaturated carboxylic acid or its derivative as a modifying component include maleic acid, maleic anhydride, maleic acid ester, maleic acid halide, acrylic acid, and acrylic acid. Examples thereof include acid esters, acrylic acid halides, methacrylic acid, methacrylic acid esters, and methacrylic acid halides, and maleic anhydride and maleic acid are preferable.
As the polyolefin resin modified by this,
For example, polyethylene, polypropylene, ethylene-α
-Olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer or ethylene-propylene-diene terpolymer Can be mentioned.

The amount of the unsaturated carboxylic acid or its derivative grafted on the modified polyolefin resin is usually 0.01 to 5% by weight, preferably 0.05 to 2% by weight, more preferably 0. It is in the range of 1 to 2% by weight. Particularly preferred as the above component,
It is a modified ethylene-butene-1 copolymer obtained by grafting maleic anhydride in an amount of 0.3% by weight or more.

The amount of the modified polyolefin resin compounded is 1 to 20 parts by weight, preferably 1 to 20 parts by weight of the modified polyolefin resin, based on 100 parts by weight of the melt-kneaded product of the composite material in which the thermosetting resin is coated on the polypropylene layer. It is in the range of 3 to 10 parts by weight. If the amount of the modified polyolefin resin blended is less than the lower limit, the impact properties of the recovered product are not sufficiently improved,
On the other hand, if it exceeds the upper limit, the mechanical strength is significantly lowered, which is not preferable.

All of the modified polyolefin resin may be a modified product with an unsaturated carboxylic acid or a derivative thereof, or may partially contain an unmodified product. further,
It may be diluted with a small amount of another resin. In this case, the content ratio of the unmodified product with respect to the modified product is not particularly limited as long as the amount of the unsaturated carboxylic acid or its derivative satisfies the above range.

The polypropylene pellets recovered in the present invention have the original high mechanical properties and appearance of the raw material resin, and can be recycled as a raw material for a polypropylene composite material with a polyurethane resin coating film.

[0020]

【Example】

Example 1 A used automobile bumper made of polypropylene with a polyurethane resin coating was crushed into 2 to 8 mm squares using a crusher, and a screw diameter of 40 mm φ twin-screw kneading extruder (L / D =
30) in the presence of 0.1% by weight of dibutyltin laurate (vs crushed product) at a temperature of 250 ° C. and melt kneading (residence time 4
0 sec), and then 5 parts by weight of modified polyethylene resin was added to 95 parts by weight of the melt-kneaded product, and melt kneading was performed at a temperature of 250 ° C. using the same kneading extruder (retention time 40 seconds). And extruded into pellets.

A screen mesh (8) provided at the outlet of the extruder in the subsequent stage after the extrusion amount of 10 kg (2 hr) has been treated.
No clogging was observed when the clogging state of (0 mesh) was observed. The modified polyethylene resin is a modified ethylene resin grafted with 0.4% by weight of maleic anhydride.
A butene-1 copolymer was used. The extruded pellets obtained above were evaluated by the following methods. The results are shown in Table-1.

(1) Clogging of screen After the extrusion amount of 10 kg was processed, the screen was removed, and the state of adhesion of the coating film was visually observed and evaluated according to the following three ranks. 1: No deposits at all, 2: Some deposits, 3: Completely clogged (2) MFR = 230 ° C in accordance with JIS K7210
The load was measured at 2.16 kg. (G / 10 minutes) (3) DDI impact strength: based on JIS K6718,-
Measured at 30 ° C (kgf · cm) Injection-molded disc (2mm thickness) (4) Tensile elongation: Measured at 23 ° C (%) according to JIS K7113 Injection-molded flat plate (JIS No. 2 dumbbell piece) (5) Flexural elasticity Rate: In accordance with JIS K7203, 23 ° C
(Kgf / cm ² ) Injection-molded flat plate (4 mm thickness) (6) IZod impact strength Measured at −30 ° C. according to JIS K7110 (kgf ·
cm / cm)

Example 2 0.4 wt% as modified polyethylene resin in Example 1
% Maleic anhydride modified ethylene-ethyl acrylate copolymer was used in the same manner except that the copolymer was used. The results are shown in Table-1.

Comparative Example 1 Example 1 was repeated except that the modified polyethylene resin was not added at all. The results are shown in Table-1.

[0025]

[Table 1]

Claims (1)

[Claims] 1. A composite material in which a thermosetting resin is coated on a polypropylene layer is crushed into small pieces, and the crushed small pieces are put into a kneading extruder and melt-kneaded at a temperature of 200 ° C. or higher. Then, 1 to 20 parts by weight of a polyolefin resin modified by an unsaturated carboxylic acid or a derivative thereof with respect to 100 parts by weight of the melt-kneaded product is obtained by finely dividing the thermosetting resin coating film by thermal decomposition and uniformly dispersing it. Is added, melt-kneaded, pelletized and recovered, and a method for regenerating a polypropylene composite material with a thermosetting resin coating film.