JPH04145158A - Photo-degradable heat-resistant interior cover of automobile - Google Patents

Abstract

PURPOSE:To obtain an interior cover of an automobile having excellent heat resistance, transparency and photo-degradation property by forming the cover out of a composition comprising modified polyethylene copolymerized with carbon monoxide and polypropylene not containing a light stabilizer nor an antioxidant. CONSTITUTION:(A) 70-85wt.% modified polyethylene obtained by copolymerization of ethylene as a principal component with 0.5-10wt.% carbon monoxide and other ethylenic unsaturated compound (preferably vinyl acetate or ethyl acrylate) preferably in an amount of 1-20wt.%, as necessary, is mixed with (B) 15-30wt.% polypropylene not containing a light stabilizer nor an antioxidant at all obtained by homopolymerization of propylene using a catalyst of Ziegler-Natta system, etc., or copolymerization of propylene and other alpha-olefin to obtain a resin composition. Next, the composition is molded to a filmy state and cut into a fixed shape, then heat-sealed to afford a photo-degradable heat- resistant interior cover of an automobile.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a photodegradable heat-resistant automobile interior cover used for packaging automobile interior components.

[Prior Art] The automobile industry is a typical assembly industry, and many parts such as fittings, electrical components, body structures, suspension systems, restraint systems, ventilation systems, transmission systems, exhaust systems, tires, It is made by assembling wheels, steering gear, brake control equipment, engine, fuel system, etc., and assembling the parts one by one on an assembly line.

Some of these parts or structures are installed internally by automobile manufacturing companies, while others are manufactured by external companies and delivered to automobile manufacturing companies. Among these parts or structures, the fittings, particularly seats, doors, inner walls, ceilings, sunshades, etc., are provided to the user in a state covered with a resin film cover.

Conventionally, polyethylene films, which are inexpensive and have excellent processability, transparency, and strength, have been used for automobile interior parts covers.

In recent years, the automobile industry has been required to improve safety, reduce costs, and protect the environment, and automobile interior covers must also meet these demands, and conventional polyethylene is no longer able to meet these demands. It's here.

In other words, ■For safety, we need to be able to withstand heat even when the inside of the car reaches high temperatures.■For cost reduction, we need to ensure that the fittings made by an outside company meet the standards when they are accepted into the automobile manufacturing line. Visual inspections are conducted through automobile interior covers, but if the transparency of automobile interior covers is poor, the inspection will take time and increase costs, so it is important to have sufficient transparency. When the car is handed over to the user and the car starts to be used, these car interior parts covers are removed from the equipment and discarded, but if they do not disintegrate in the natural environment, it will lead to environmental damage, so they must not be photo-degradable. In recent years, it has become particularly important to satisfy requirements such as: Traditional polyethylene covers do not photodegrade in the natural environment.

By the way, as a photodegradable polyolefin composition,
For example, Japanese Patent Application Laid-Open No. 50-34044 discloses a resin composition which has a polyolefin containing an oxidation stabilizer as its main component, and which is blended with a copolymer of ethylene and carbon monoxide to impart photodegradability. be. However, although this resin composition has photodegradability, it has insufficient heat resistance and transparency.

[Problems to be solved by the invention] The present invention has been made in view of the above circumstances, and provides a method for replacing automobile interior parts covers made of polyethylene film.
The purpose of the present invention is to provide an automobile interior cover with excellent heat resistance, transparency, and photodegradability.

[Means for Solving the Problems] The present inventors have developed a number of materials that simultaneously satisfy the properties such as heat resistance, transparency, and photodegradability required for automobile interior parts covers, and have appropriate strength and processability. After studying these combinations, we discovered and completed an automobile interior parts cover having the following structure according to the present invention.

The automobile interior parts cover of the present invention contains 70 to 85% by weight of modified polyethylene copolymerized with ethylene as a main component and 0.5 to 10% by weight of carbon monoxide, and does not contain light stabilizers or antioxidants. It is formed from a resin composition consisting of 15 to 30% by weight of polypropylene.

This modified polyethylene has ethylene as its main component and is a copolymer of carbon oxide or carbon monoxide and an ethylenically unsaturated compound, and maintains the transparency and photodegradability of molded products.

The amount of carbon monoxide in the modified polyethylene is 0.5-10% by weight. -The copolymerization ratio of carbon oxide is 0.5% by weight
If it is less than 10% by weight, the photodecomposition rate will be extremely low, and if it exceeds 10% by weight, the photodecomposition rate will be too high and the strength will decrease in a short time, which is not preferable for molded products. In addition, examples of ethylenically unsaturated compounds copolymerized with -carbon oxide include vinyl acetate, acrylic acid, methyl acrylate,
Ethyl acrylate, methacrylic acid, methyl methacrylate, maleic acid, fumaric acid, acrylonitrile, acrylamide, vinyl methyl ether, vinyl phenyl ether, styrene, vinyl chloride, propylene, butene-1,
Examples include hexene-1, octene-1, decene-1,4-methylpentene-1, but cost, film strength, etc.
Vinyl acetate and ethyl acrylate are particularly preferred in terms of heat resistance, gloss, haze value, and the like.

Additionally, modified polyethylene, which is made by copolymerizing ethylenically unsaturated compounds such as vinyl acetate and ethyl acrylate with carbon oxide, not only improves the transparency of automobile interior parts covers, but also causes rapid photodegradation after a certain period of time. . When this ethylenically unsaturated compound is copolymerized, the copolymerization ratio is preferably in the range of 1 to 20% by weight. 1% by weight
If it is less than 20% by weight, the effect of copolymerization will not be exhibited, and if it exceeds 20% by weight, the strength of the film will decrease and processability will deteriorate, which is not preferable.

In the present invention, polypropylene that does not contain light stabilizers and antioxidants is produced using a slurry method, solution method, gas phase method, or their ( It is obtained by homopolymerizing propylene or copolymerizing propylene and other α-olefins by a known method such as for JF.This polymer is completely free of light stabilizers and oxidative stabilizers. It is not added.

Normally commercially available polypropylene is a polymerized base resin that is easily excited by heat or light, generating radicals, which react with oxygen and oxidative deterioration progresses. is blended. Since the purpose of the present invention is to produce a photodegradable molded article, polypropylene to which no stabilizer is added is used. By blending polypropylene that does not contain this stabilizer, the photodegradability of the entire resin can be appropriately balanced.

This polypropylene is used to improve the heat resistance, strength, and processability of the resin composition, and is a modified polyethylene of 70 to 85%.
It is blended in an amount of 15 to 30% by weight. If the amount of modified polyethylene is less than 70% by weight and the amount of polypropylene is more than 30% by weight, the mechanical strength as an automobile interior parts cover will be insufficient, the transparency will be poor, and melt fracture will occur during processing. So I don't like it.

If the amount of modified polyethylene is more than 85% by weight and the amount of polypropylene is less than 15% by weight, it will not meet the heat resistance standards for automobile interior parts covers and the photodegradability will be slow, which is undesirable.

Modified polyethylene can be produced by the following method. For example, using a polyethylene manufacturing equipment, the reaction temperature is 150
Dilauroyl peroxide, tert-butyl peroxide, t-butyl perisobutyrate, t-butyl peracetate or α,α'-azobisisobutyronitrile under conditions of ~300°C and a pressure of 500-8000 atm. A radical initiator, such as , dissolved in an inert organic solvent such as benzene, kerosene or mineral oil, is injected into the reactor to copolymerize ethylene with carbon monoxide and optionally an ethylenically unsaturated compound. method, using a polyethylene manufacturing equipment, reaction temperature 5
Ethylene and It can be produced by copolymerizing carbon monoxide and, if necessary, other ethylenically unsaturated compounds.

The resin composition contains pigments, cross-linking agents, lubricants, processability improvers, antistatic agents, nucleating agents, antifogging agents, flame retardants, and antibacterial agents to the extent that they do not impair photodegradability, heat resistance, and transparency. agent,
Deodorizers, fragrances, salmon temperature retaining agents, infrared radiation agents, etc. may also be added.

This resin composition can be produced by a conventional kneading method using a Banbury mixer, a pressure kneader-1 twin-screw extruder, a Busco kneader, a Henschel mixer, a Roll kneader, etc., by mixing the resin component, the above-mentioned compound, and the like.

In order to manufacture an automobile interior parts cover from this resin composition, a film can be made by an inflation method, a calendar method, a casting method, etc., cut into a predetermined shape, and heat-sealed.

[Example code] Hereinafter, this will be explained in detail using examples.

(Example 1) Edylene carbon oxide copolymer with a carbon monoxide content of 0.9% [manufactured by Union Carbide, DXM-43]
9. Melt index (MI) 0.7 (190°C)]
88% by weight and 15% by weight of polypropylene without light stabilizers and antioxidants [Melt Flow Rate (MFR) 9 (230°C) manufactured by Tonen Petrochemical Co., Ltd.] were kneaded in a Banbury mixer to form pellets. A resin composition was obtained.

Using this resin composition, a film with a thickness of 50 μm was produced at 190° C. using an inflation extruder with a diameter of 50 m/m. This film was evaluated using the following evaluation method. The results are shown in Table 1.

Orientation: The strength of the film was evaluated using a ratio of 0.4 or more as ○ and a ratio of 0.4 or less as X.

Photodegradability: Measure the remaining elongation after exposing the film for 70 hours using a sunshine type weather-o-meter, and it is 50%.
Those above were rated as X, those with 30 to 10% were rated as ○, and those with 10% or less were rated as ◎.

Processability: When melt fracture occurred during film molding, it was evaluated as ×, and when it did not occur, it was evaluated as ○.

Heat resistance: Place the film in a chamber at 120°C,
When taken out after a minute, those that remained intact were marked as ○, and those that had shrunk were marked as X.

Transparency: Those with a cloudy value of 8 or more were rated as ×, and those with a cloudy value of 8 or less were rated as O.

(Examples 2 to 6) In Example 2, the amount of carbon monoxide in modified polyethylene was 0.
A resin film was produced in the same manner as in Example 1, except that 5% by weight and MI=0.7 were changed to 80% by weight.

In Example 3, a resin film was produced in the same manner as in Example 1, except that the amount of carbon monoxide in the modified polyethylene was 3% by weight and the MI=2 was 75% by weight.

In Example 4, a resin film was produced in the same manner as in Example 1, except that the amount of carbon monoxide in the modified polyethylene was 10% by weight and the MI=5 was 70% by weight.

Example 5 is a copolymer prepared by copolymerizing modified polyethylene with 5% by weight of carbon monoxide and 7% by weight of vinyl acetate, and has an MI of 6.
A resin film was produced in the same manner as in Example 1, except that the amount was changed to 75% by weight.

In Example 6, modified polyethylene was made of a copolymer of 2% by weight of carbon monoxide and 5% by weight of ethyl acrylate, and the MI=3 was 80.
A resin film was produced in the same manner as in Example 1 except that the weight was increased.

(Comparative Example) In Comparative Example 1, a resin film was produced in the same manner as in Example 1, except that the modified polyethylene was increased to 95% by weight, which was higher than in Example 1.

In Comparative Example 2, the modified polyethylene was the same as in Example 3, but the amount was 6.
A resin film was produced in the same manner as in Example 1, except that the amount was reduced to 5% by weight.

In Comparative Example 3, the modified polyethylene was the same as in Example 4, but the amount was 8.
A resin film was produced in the same manner as in Example 1 using polypropylene containing 0% by weight of a light stabilizer and an oxidation stabilizer.

In Comparative Example 4, a resin film was produced in the same manner as in Example 1, except that 80% by weight of polyethylene not copolymerized with carbon monoxide was used.

(Evaluation Results) According to the evaluation results in Table 1, Examples 1 to 6 satisfied all of orientation, photodegradability, processability, heat resistance, and transparency. On the other hand, when the amount of modified polyethylene in Comparative Example 1 reaches 95% by weight, the heat resistance decreases. When the modified polyethylene of Comparative Example 2 reaches 65% by weight, the photodegradability is good, but the orientation, processability, and transparency deteriorate. When the polypropylene blended with the stabilizer of Comparative Example 3 is used, it no longer exhibits photodegradability. Further, when high-pressure low-density polyethylene is used instead of modified polyethylene as in Comparative Example 4, photodegradability does not occur.

Therefore, an automobile interior cover made of a resin composition of a specific amount of modified polyethylene copolymerized with -carbon monide and polypropylene free of light stabilizers and oxidation stabilizers has photodegradable heat resistance and transparency. It has moderate strength and workability.

[Effects of the Invention] The automobile interior parts cover of the present invention contains polypropylene in order to improve the heat resistance of modified polyethylene, which is photodegradable, transparent, and has an appropriate strength. In order to promote photodegradability, polypropylene does not contain light stabilizers or oxidative stabilizers. Therefore, by blending both of them in a specific ratio, it is possible to form an automobile interior parts cover that has desired strength, heat resistance, transparency, and photodegradability.

Moreover, even when a car is used in a region with high temperatures, the car interior cover made of this resin composition will not be deformed and its appearance will not deteriorate. Also, since it is highly transparent, it is easy to inspect products upon delivery. Furthermore, even if this cover is discarded in the natural environment, it has good photodegradability, so it easily disintegrates and does not remain in its original form, contributing to environmental beautification.

Patent applicant: Toyota Motor Corporation

Claims (1)

[Claims] Consists of 70-85% by weight of modified polyethylene, which is copolymerized with ethylene as the main component and 0.5-10% by weight of carbon monoxide, and 15-30% by weight of polypropylene that does not contain light stabilizers or antioxidants. A photodegradable heat-resistant automobile interior parts cover made of a resin composition.