JPS6185448A - Method of processing molded article of plastic - Google Patents

Abstract

PURPOSE:To obtain a molded article of plastic having improved adhesivity and durability, and to bond another material to the molded article in sufficient strength, by irradiating the surface of the molded article of plastic in the presence of a chlorohydrocarbon. CONSTITUTION:A molded article of plastic (e.g., polyolefin, etc.) is brought into contact with vapor and/or liquid of a chlorohydrocarbon (e.g., tetrachloroethylene, etc.), the surface of the molded article is kept in a state where the chlorohydrocarbon remains, and irradiated with ultraviolet light rays in atmosphere, and a material such as coating compound, printing ink, adhesive, etc. which are preferably ultraviolet-curing, is applied to the surface of the molded article.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming another material on the surface of a plastic molded article with sufficient adhesive strength.

(Prior art) Styrene resins have traditionally been widely used as molding materials, such as in automobile radiator grills, television cabinets, etc., but polyolefin resins have been used from the viewpoint of cost, supply stability, weight reduction, etc. are increasing.

Although polyolefin resin has many advantages such as being low cost, lightweight, and easy to mold, it has a high degree of crystallinity and low polarity, so it has poor adhesion to various materials for ponds and is difficult to paint, plate, and bond. Currently, there are only a few special paints that have been put into practical use. Therefore, various modification techniques are being considered to improve the adhesion by surface modification of polyolefin resins.

■When using chlorinated polyolefin υ4 resin, which has undergone resin modification by partially or completely chlorinating, as a material, a corresponding effect of improving adhesion is observed, but it lacks versatility and has poor performance such as weather resistance. Problems arise in terms of cost, etc.

■ Mechanical treatments such as sanding and brushing, and physicochemical treatments such as cleaning by fusing and surface roughening can be performed relatively easily, but the surface treatment effects are insufficient and durability is poor.

■Flame treatment, acid treatment, corona discharge treatment, glow discharge treatment, radiation grafting treatment, etc. have shown excellent treatment effects, but many practical problems remain, such as equipment costs and difficulty in mass production. There is.

■Surface treatment using ultraviolet irradiation has many advantages, such as relatively inexpensive equipment, easy handling, and non-polluting properties, but simple irradiation has small modification effects and has not been put to practical use.

■Japanese Patent Publications No. 56-29891 and No. 56-29892 disclose that polyolefin resin in halogen gas or liquid halogen is halogenated by irradiating light, usually ultraviolet rays, and then subjected to 7 reel or alkali treatment. This method modifies the surface and improves adhesion, but this method still has operational problems such as the use of toxic halogen gas and the positioning of the ultraviolet light source in the rodene liquid. There are many practical inadequacies, such as the need for secondary processing such as oxidation.

(Problems to be Solved by the Invention) The purpose of the present invention is to provide highly practical plastic molding that can be carried out safely and easily without using any harmful gases such as rodents. The goal is to provide a method for processing products.

Another object of the present invention is to provide a method for processing plastic molded products with excellent adhesion and durability.

(Means for Solving the Problems) The present invention maintains the surface portion of the molded article in a state where chlorinated hydrocarbon remains after the plastic molded article is brought into contact with chlorinated hydrocarbon vapor and/or liquid. The present invention relates to a method for processing a plastic molded product, which comprises irradiating the molded product with ultraviolet rays in the atmosphere, and then attaching a pond material to the surface of the molded product.

In the present invention, polyolefin is preferably used as the material for the plastic molded product, but other materials include polystyrene, styrenic resins such as AB S If resin, polyamides such as nylon, and polyethylene tele7.
Polyesters such as Grate, polycarbonates, cellulose derivatives such as cellulose acetate resins, acrylic resins such as polymethyl methacrylate, etc. can be used.

Specific examples of polyolefins include ethylene, propylene, 1-butene, 1-hexene, and 4-methylpentene-1.
, 1-octene and other α-ole7 homopolymers or copolymers, or chlorinated products thereof;
- Mention may be made of copolymers of olefins and vinyl monomers such as vinyl acetate, styrene, (meth)acrylic acid, (meth)acrylic acid esters. Taking polypropylene as an example, for example, isotactic polypropylene, atactic polypropylene, propylene-ethylene random copolymer, propylene-vinyl acetate copolymer,
Examples include propylene-styrene copolymer, propylene-acrylic ester copolymer, EPDM, and chlorinated polypropylene.

In the present invention, molded products obtained by molding the above-mentioned various plastic materials by known molding means such as extrusion, injection, blowing, compression, fa layer, casting, etc. are used.

Examples of chlorinated hydrocarbons include tetrachlorethylene,
Trichlorethylene, dichloroethylene, pentachloroethane, 1,1,2.2-tetrachloroethane, 1,1
．． 1-) Dichloroethane, 1,1.2-) Dichloroethane, 1. Z-dichloroethane, Te)? Examples include 90 lumethane and trichloromethane.

In the present invention, after the plastic molded article is brought into contact with chlorinated hydrocarbon vapor and/or liquid, the surface of the molded article is maintained in a state in which chlorinated hydrocarbon remains and is irradiated with ultraviolet rays in the atmosphere. , attaching other materials to the surface of the molded product.

As the ultraviolet rays, it is possible to use ultraviolet rays from various light sources, such as sunlight, low-pressure, high-pressure, or ultra-high-pressure mercury lamps, carbon chloride lamps, xenon lamps, tungsten lamps, and the like.

The UV irradiation conditions can be selected from a wide range, but for example, a 500W high-pressure mercury lamp can be used at a distance of 0.5 to 10 cm from a distance of 30 cm.
It is preferable to irradiate the UV rays for a minute, but irradiation with ultraviolet rays for too long is not preferable because it may cause deterioration of the plastic material.

Various other materials can be used in the present invention, and specific examples include paints, printing inks, adhesives, and metals such as aluminum, silver, and nickel. If other materials have UV curability,
A particularly preferable example of this is an ultraviolet curable resin composition, since ultraviolet rays can be used in the process of modifying the surface of the molded article. This composition is made of, for example, a polymer or prepolymer having a polymerizable ethylenic double bond [e.g., polyester resin, polyurethane resin, epoxy resin, etc., as a backbone, intramolecular unsaturated bonds, terminal (
A resin composition consisting of a polymer or prepolymer containing a meth)acryloyl group, a polymerizable monomer, and a photopolymerization initiator, and may optionally contain fillers, dyes, pigments, etc.

In the present invention, methods for attaching other materials to the surface of the above-mentioned modified plastic molded product include, for example, placing the other material on and heating it, and evaporating metals in a vacuum to attach the other material to the surface of the molded product. There are methods such as adhesion, and if the other material is ultraviolet curable, there is a method of irradiating it with ultraviolet rays after +111ii1.

(Effects of the Invention) According to the method of the present invention, a plastic molded product with markedly improved adhesion can be obtained through simple processing, and then other materials can be adhered to this with sufficient strength. Although the reason for the improved adhesion is not fully clear,
When chlorine-based hydrocarbons remain on the surface of plastic materials, chlorine radicals or oxygen radicals are generated by irradiation with ultraviolet rays, causing some kind of chemical reaction on the resin surface, introducing polar groups such as hydroxyl groups, and causing adhesive properties. It is inferred that the surface is modified to be good.

Furthermore, according to the method of the present invention, subsequent steps such as painting and adhesive application can be carried out continuously after the ultraviolet irradiation treatment step, so that it is possible to prevent the adhesion of dust, etc. and to improve the efficiency of the process. can.

Furthermore, in the method of the present invention, if the material to be attached to the plastic molded product is UV curable, it can be used in conjunction with the UV irradiation device for surface treatment, reducing equipment costs and
This is very advantageous in terms of space saving.

(Example) Examples and comparative examples will be described below.

Example 1 ■ Trichlorethylene steam cleaning island ■ Ultraviolet irradiation device W1 (1 kW high-pressure mercury lamp, irradiation distance 10
c) ■Painting machine■Hot air drying fi (100°C) The processing devices were arranged in the order of (1) to (2) above, and a conveyor was provided so that the workpiece could be moved while undergoing each process successively. The apparatus was arranged so that the passing time was 3 minutes for processing (2) and 1 minute for processing (2).

The distance between the machines for processing ■ and ■ was made as small as possible.

The coating machine (■) is a spray type, and the paint composition is shown below.

Nihon Yushi Co., Ltd. High Urethane No. 5000 Clear main agent/curing agent = 571 (weight ratio) 30 parts thinner
The 70-part coating treatment time was 1 minute. Also, the drying time for ■ is 10
It was set as 1 minute.

A commercially available polypropylene extrusion plate was attached to a conveyor, and processing steps ① to ③ were performed. The obtained processed product (A>) was examined for its coating state and adhesion.

The results are shown in Table 1.

For comparison, a processed product (B) without ultraviolet irradiation in processing (1) was prepared after hot air drying at 80°C for 30 minutes between processing (2) and (2) to sufficiently dry trichlorethylene on the surface of the polypropylene plate. Processed products obtained by returning to processing (
C), After further processing ■, remove from the conveyor and store at 70°C.
A similar experiment was conducted on a processed product (D) obtained by immersing it in the chromic acid mixture and returning it to the process (2).

Chromic acid mixed solution treatment method 2CrzOt:H2SO, :)+20=4.
5:90:7 (weight ratio) Immersion conditions: 70°C, 10 minutes water washing, 20 minutes hot air drying, 100°C, 30 minutes 1st Surface adhesion test (1): Place 1 IImII square on the coating surface.
00 pieces, cut out the edges with a cutter knife in the shape of a goblin, and paste cellophane tape on top5. It's hard to peel off,
Evaluation was made based on the number of squares remaining.

Adhesion test (2) is a test to check the durability of the paint film,
The coating film was placed in a constant temperature and humidity chamber adjusted to 70°C and 95% RH.
After 00 hours of humidification and heating, a test similar to the above adhesion test (1) was conducted.

As shown in Table 1, in the processed product (A) of Example 1, as a result of continuous coating curing and drying following resin surface cleaning and ultraviolet irradiation treatment, dust was difficult to adhere to the coating surface, and the surface was modified. The effect of improving adhesion depending on the quality is clearly recognized.

Although it was possible to prevent dust from adhering to the comparative processed product (B),
Mere steam cleaning did not improve adhesion.

In processed product (C), a small amount of trichlorethylene remained on the resin surface, and although some effect of combined use with ultraviolet irradiation was recognized, it was insufficient.

In the processed product (D), due to the chromium mixed acid treatment, it was removed from the conveyor and moved before and after the treatment, making it easy for dust to adhere, resulting in poor coating film appearance. In addition, the adhesion of the paint film according to the adhesion test (1) was good, but the adhesion test (2)
The adhesion properties are considerably reduced.

Example 2 The processing apparatus of Example 1 was arranged in the order of ■→■→■→■→■, and a conveyor was similarly provided. Processing time is 03 minutes,■
The conditions were 1 minute, 01 minutes, 080°C, and 30 seconds. As the coating material, the ultraviolet curable resin composition (1) of Reference Example 1 was used.

Attach a commercially available polypropylene press plate to the conveyor■〜■
Processing was performed in the order of , and then .

The properties of the coating film of the obtained new coating were investigated.

Paint film appearance No abnormality adhesion test (1) 100/100 adhesion test (2
) 100/100 Reference Example 1 Ebico in a reactor with a stirring device) 1001 (molecular weight 9
00, epoxy equivalent 475) 225.9g, noethanolamine 48.0g, dioxane 274.5g and hydroquinone 0.55g. and heated to 108.5℃,
A modified epoxy resin solution (A) in which the epoxy group was ring-opened was obtained by reacting for about 3 hours under refluxing nooxane.

Meanwhile, tolylene diisocyanate (
TDI (75.0 g) was added, heated to 80°C, and Vyron RV 2001- (molecular weight 1940, manufactured by Toyobo Co., Ltd., terephthalic acid polyol) 418. ig, Nooxane 493, 35g, dibutyltin dilaurate 0.2
Gradually drop 5g of the mixed solution and heat to 90°C for about 30 minutes.
Allowed time to react.

The above reactant 971.
3 g was added and heated to 80°C, and a mixed solution of 2-hydroxyethyl acrylate (ethylene glycol monoethyl acrylate) 22,15.1 hydroquinone 1.08 and 22.25 g of nooxane was gradually added dropwise and allowed to react for about 3 hours. A urethane prepolymer (B) was obtained.

Also, instead of the above Vylon RV200L, polycaprolactone polyol (trade name Plaxel 220, Molecule 120
Urethane prepolymer surface cleaning was obtained in the same manner except that 00) was used.

The modified epoxy resin obtained above (A 1t7s, Og) was placed in a reactor equipped with a stirring device, heated to 80°C,
56 urethane prepolymers (B) and (C) each
9, 4g and 380. Gradually add Og mixed solution and react for about 1.5 hours to form unsaturated polyurethane resin bath 1.
ffl(1) was obtained. This solution had a solid content of 50% and contained 0.78 meq/g of OH groups in the solid content.

(that's all)

Claims (3)

[Claims] (1) After bringing a plastic molded article into contact with chlorinated hydrocarbon vapor and/or liquid, the surface of the molded article is maintained in a state where chlorinated hydrocarbon remains, and after irradiation with ultraviolet rays in the atmosphere, A method for processing plastic molded products characterized by attaching another material to the surface of the molded product. (2) The method according to claim 1, wherein the other material is a paint, printing ink, or adhesive. (3) The method according to claim 1 or 2, wherein the other material is UV curable.