JPS59193931A - Coating of light- or radiation-curable resin composition on polyolefin molded article - Google Patents

Abstract

PURPOSE:To provide the coated surface of titled article with high scratch resistance, hardness and adhesiveness (peel strength), by the corona discharge or flame treatment of the adhesive surface of the article to give it a specific surface tension followed by coating a light- or radiation-curable resin composition. CONSTITUTION:The adhesive surface of a molded article consisting of polyolefin or the same and polar group-contg. olefin polymer is subjected to corona discharge or flame treatment to give said surface a surface tension 38-65 dynes/cm<2>. Subsequently, a primer solution as the vehicle, is undercoated on the above surface followed by drying. The resulting surface is then coated with a light- or radiation-curable resin composition. The primer solution contains, e.g., 0.01-90wt% of at least one sort of olefin polymer having one or more polar groups of formula -X, -OCOR, -COOR, -OR, formula II, III, or III (X is halogen, R and R' are each H or 1-8C hydrocarbon).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for applying light or radiation to polyolefin resin molded articles. More specifically, various plastic molded products (hereinafter referred to as plasti or plastic molded products) are made by using polyolefin or a composition of polyolefin and an olefinic polymer compound having a polar group to be used as necessary, by pressure molding, extrusion molding, injection molding, etc. After obtaining a pressure molded, extrusion molded, or injection molded product, the adhesive surface of the molded product is subjected to corona discharge treatment or flame treatment to increase the surface wetting tension of the adhesive surface to 38 dynes/cd or more, 65 dynes/cd or more. After surface treatment to dyne/d or less, an olefin having at least one polar group (wherein X is a halogen, R and 几' are H or a hydrocarbon group having 1 to 8 carbon atoms) is applied as necessary. At least one type of polymeric compound based on 0. O1～
The present invention relates to a method in which a primer solution containing 90% by weight is applied as an undercoat, dried, and a resin composition is applied to the surface by light or radiation curing.

Polyolefin has excellent mechanical properties such as rigidity and tensile strength.
Moreover, it has the disadvantage that it cannot be used in a wide range of applications because it has high chemical resistance and excellent processability.

Possible methods to overcome these drawbacks include a method of blending a modifier and a method of applying it to the surface. However, the former deteriorates other physical properties of the polyolefin, and the latter has the problem that good adhesion between the coating agent and the polyolefin cannot be obtained because the polyolefin is a nonpolar polymer.

As a result of intensive studies to solve these problems, the inventors of the present invention have found a method that provides good adhesion and improves hardness and scratch resistance, leading to the present invention.

That is, after subjecting the polyolefin composition to a roller discharge treatment, if necessary, a primer solution consisting of an olefin-based polymer compound having a polar group is applied, dried, and a light-curing, radiation-curing, or radiation-curing resin composition is applied to the surface. This is the way to do it.

Typical polyolefins used in the present invention include polyethylene, polypropylene, ethylene-propylene copolymer, propylene-ethylene-butene terpolymer, ethylene-pentene copolymer, polybutene, and combinations thereof. Can be mentioned.

Furthermore, the olefin-based polymer compound having a polar group that can be mixed with the polyolefin improves the paintability of the polyolefin, and preferably has a structure that has affinity with the paint to be applied. Examples of such polar groups include the general formula 1000R,, -COO几,
-0 liters.

(hydrocarbon group).

Examples of such compounds include ethylene-vinyl acetate copolymer or its partially saponified product, ethylene-acrylic (methacrylic) acid copolymer, ethylene-acrylic (methacrylic) acid ester copolymer or its partially hydrolyzed product, ethylene, etc. -Maleic anhydride copolymer or its partially hydrolyzed molecule 8V'1L partially esterified product, ethylene-glycidyl methacrylate copolymer or its partially ring-opened product with organic acid, primary amine, secondary amine, acrylic of polypropylene Examples include acid-modified products, polypropylene modified with maleic anhydride, and ethylene-methacrylic acid dialkylaminoethyl ester. Such an olefin-based polymer compound having a polar group has the effect of changing the surface tension of the polyolefin and increasing the adhesion strength of the paint, but if it is added in an amount of 50 parts by weight or more, the desired physical properties of the polyolefin cannot be maintained.

Furthermore, if necessary, a styrene elastomer such as a styrene-butadiene random copolymer or a styrene-butadiene block copolymer may be added to improve the adhesion of the paint. Glass fiber, talc, etc. as necessary.
0 to 40 parts by weight of various fillers such as wood flour and calcium carbonate may be added.

As a means of improving the adhesion between polypropylene resin and adhesive, our researchers investigated various methods such as the use of a primer, the use of modified polyolefin as an adhesive layer, and surface treatment of polypropylene resin, and to our surprise, we found that polypropylene resin It was discovered that the surface of a resin molded article is subjected to corona discharge treatment or flame treatment to firmly adhere to a light- or radiation-curable resin composition, leading to the present invention.

For corona discharge, a gap is created between an electrode connected to a high voltage generator and a ground electrode covered with a dielectric material, and when a high voltage is applied, a high voltage corona is generated in the gap.

This surface treatment using corona discharge is called corona discharge treatment and is generally used for surface treatment of film-shaped molded products. Corona treatment intensity is adjusted by processing power and processing time. As the corona treatment apparatus of the present invention, a commercially available treatment apparatus is usually sufficient, but if the thickness of the object to be treated is 5 mm 1 or more, a corona treatment apparatus having a maximum output of 2 KW or more is preferable. Regarding the treatment strength, it is necessary that the surface torsion tension of the treated object immediately after treatment is 38 dynes/d or more, and if it is less than that, the treatment has little effect on adhesion. Furthermore, if the treatment is too strong, there is a tendency for the surface of the object to be treated to decompose and the adhesive strength to decrease. For this reason, it is desirable that the upper limit of the treatment strength be such that the surface wetting tension is 65 dynes/d or less.

Flame treatment is a surface treatment method in which fire with sufficient excess air at t,ooo~2.800°C is blown onto the surface of the treated object for a short period of time, and the treatment strength is the same as that of corona treatment. The body surface wetting tension is desirably 38 dynes/i or more and 65 dynes/i or less, and 42 dynes/d or more and 5
Application of a light- or radiation-curable resin composition to 5 dabs can be practically achieved, but if necessary, the following primer solution can be applied as an undercoat, dried, and then a light- or radiation-curable resin composition can be applied for further adhesion. May increase sexual effects.

Such primers may have the general formula -
x, -oco几, -COO几, -OR.

(X is a halogen, and R and R' are H or a hydrocarbon group having 1 to 8 carbon atoms.) At least one olefinic polymer compound having at least one polar group represented by Primer solutions containing % heavy weight can be used.

Such polar groups include general formulas -X, -oco
几.

(1) or a hydrocarbon group having 1 to 8 carbon atoms), and the proportion of such a polar group moiety is preferably 1 to 60% by weight based on the solid content of the olefinic polymer compound. If it is less than 1% by weight, the effect of the polar group will be poor and it will not adhere well to the cured resin composition for top coating.
On the other hand, if it is 60% by weight or more, there are too many polar groups and it is difficult to adhere to the molded article made of the polyolefin composition. Two or more of these polar groups may be used in combination for the purpose of enhancing adhesion.

Such compounds include, for example, chlorinated polyethylene,
Brominated polyethylene, chlorinated polypropylene, chlorinated ethylene-propylene copolymer, ethylene-vinyl acetate copolymer or partially saponified product thereof, maleic anhydride modified ethylene-vinyl acetate copolymer, ethylene-acrylic (methacrylic) ) acid copolymer, ethylene-acrylic (
methacrylic acid ester copolymer or its partial hydrolyzate, ethylene-maleic anhydride copolymer or its partial hydrolyzate, partial esterified product, ethylene-methacrylic acid ester copolymer or organic acid, class amine,
Examples thereof include partially ring-opened products thereof with secondary amines, polypropylene modified with acrylic acid, polyprohylene modified with maleic anhydride, and ethylene-methacrylic acid dialkylaminoethyl ester.

The solvent used in the primer is preferably one that is industrially easily available, has appropriate volatility, and can completely dissolve or uniformly disperse the primer vehicle. For this purpose, for example, as mentioned above, halogenated aliphatic hydrocarbons such as carbon tetrachloride, trichloroethylene, 1.1.1-)lychloroethane, and aromatic hydrocarbons such as toluene, xylene, benzene, decalin, tetralin, etc. Examples include hydrocarbons, halogenated aromatic hydrocarbons such as chlorobenzene, ketones such as acetone and gemethyl ethyl chloride, and tetrahydrofuran, which can be used alone or as a mixed solvent of two or more.

This primer can be applied to the surface of the polyolefin resin molded product using a brush, brush, spray, etc.
It is a simple method of immersing the plastic molded article in an undercoat liquid, and does not require equipment costs.

After corona discharge treatment or flame treatment, an undercoat is applied and dried, if necessary, and a light- or radiation-curable resin composition is further applied to the surface.

Examples of light- or radiation-curable resins used in the present invention include conventionally known unsaturated polyester resins, urethane acrylic resins, melamine acrylic resins, acrylated polyester resins, and polyester acrylic resins. It can be used in one type or in a combination of two types.

In addition to the above-mentioned light- or radiation-curable resins, commonly used ethylenically unsaturated monomers for the purpose of viscosity adjustment or crosslinking, such as styrene, vinyl acetate, 2-vinylpyridine, N-vinylpyrrolidone, and N-vinyl carno- Kuzol, methyl acrylate, ethyl acrylate, butyl acrylate, lauryl acrylate, stearyl acrylate, benzyl acrylate, bitroxyethyl acrylate, cyclohexyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1.6- Hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, methacrylic acid, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1
．． 6-hexanediol diacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, etc. can be used.

Of course, these may be used alone or in combination of two or more.

Further, in order to impart properties such as flexibility, polymers such as saturated polyester resins, acrylic resins, alkyd resins, and ethylene-vinyl acetate copolymers, pigments, colorants, plasticizers, etc. may be used in combination with the features of the present invention. It's okay as long as it doesn't damage it.

In order to cure the light- or radiation-curable resin composition of the present invention with ultraviolet rays or electron beams, benzoins such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzophenone, ketones such as micellar ketone, azobisiso This can be carried out using known photopolymerization initiators such as azos such as butyronitrile or quinones such as anthraquinone, or by various combinations 4 of these.

Furthermore, if necessary, the light- or radiation-curable resin of the present invention may be diluted with a solvent such as ethyl acetate or n-butyl acetate.

Methods for applying the light- or radiation-curable resin composition to the molded article include commonly used methods such as brush coating, spray coating, and dipping.

The present invention will be explained below with reference to Examples.

Synthesis Example 1 Isophorone diisocyanate) 222.8g 1 acetic acid n
-Butyl 114f/ is charged into a flask equipped with a stirrer, thermometer, and cooling condenser, and 2-hydroxy
ethyl acrylate) 189.8g, phenothiazine 0.
114 g was added and reacted at 90'C for 8 hours to obtain a pale yellow viscous resin liquid.

Desmophene $1l150 209f (dibutyltin diacetate) 0.209F manufactured by Sumitomo Bayer Urethane was added dropwise to the above resin liquid and reacted at 90°C for 4 hours to obtain a pale yellow viscous resin liquid (A). .

Example 1 Sumitomo Noblen AD571 (MI = 0.6, a test piece with a thickness of 5 mm was made by extrusion molding of propylene-ethylene block copolymer, and was treated using a corona discharge treatment machine HF8-202 manufactured by Kasuga Denki ■). The test piece was treated so that the surface wetting tension on the surface became 48 to 50 dynes/d immediately after treatment.

The above-treated test piece contained 2% by weight of acrylic acid.
A toluene solution containing 5% by weight of a modified polypropylene having a chlorine content of 27% by weight obtained by chlorinating acrylic acid-modified polypropylene was used as an undercoat for spraying.

Thereafter, the coated autopsy cloth board was coated with Bar Quarter #26 (thickness: 26 u), and then irradiated 15 times with a 80 W/rN mercury lamp at a belt conveyor speed of 10 m/min.

As a result, the pencil hardness of the photocurable resin composition coated plate was H1, the surface gloss was 95% (measured by measuring the reflectance of light at an incident angle of 45° with a surface hardness meter), and the Nichiban Cellotape ■1 Koyoru 2M
The retention rate in the adhesion test of the shoulder logo panning was 100/100. Also, -20°C, 2hr → 23°C, 0.5h
r-? No abnormality was observed in the appearance after 10 cycles of 70'C and 21 ir, and in the peel test using cellophane tape. Further, no particular decrease in gloss was observed even after 400 hours of irradiation with a Sunshine Weather-O-Meter (black panel temperature: 63°C, water present).

Comparative Example 1 The polypropylene molded product used in Actual Example 1 had a pencil hardness of 2B and a surface gloss of 78%.

Comparative Example 2 A photocurable resin composition was applied in the same manner as in Example 1 except that the surface treatment by corona discharge was omitted. As a result, the residual rate of the coated plate in the peel test with Sellotape was 65/100. there were.

Example 2 90 parts by weight of an inorganic material-filled polyolefin consisting of 80% by weight of homopolypropylene with a melt index of 8 and 20% by weight of talc, 90 parts by weight of an inorganic material-filled polyolefin consisting of 82% by weight of ethylene and 18% by weight of glycidyl methacrylate, and ethylene with a melt index of 50. 10 parts by weight of a copolymer with glycidyl methacrylate was mixed and passed through an extruder to obtain a molding resin. This was molded using an injection molding machine at a molding temperature of 230°C.
An injection molded plate with a thickness of 214M, a width of 9Qjlff, and a length of 15MW was molded and subjected to a test.

The molded plate was subjected to frame treatment so that the wetting tension on the surface of the molded plate was 45 to 50 dynes/i.

The same photocurable resin composition as in Example 1 was applied to this treatment liquid without applying an undercoat and irradiated.

As a result, the pencil hardness of the coated plate was 2■, and the peel test retention rate with cellophane tape was 100/100.

Comparative Example 3 The polypropylene composition molded plate used in Example 2 had a pencil hardness of B.

Comparative Example 4 Coating and irradiation were carried out in the same manner as in Example 2, except that the frame treatment was omitted.

As a result, the residual ratio of the coated plate in the peel test using cellophane tape was 60/100.

Comparative Example 5 Coating and irradiation were carried out in the same manner as in Example 1, except that the surface wetting tension immediately after the corona discharge treatment was adjusted to 30 to 35 dynes/d.

In addition, Example 1 except that the surface wetting tension immediately after the corona discharge treatment was treated to be 70 gain/C1A (wettable with water).
Apply and irradiate in the same manner as above.

As a result, the residual rate of the coated plate in the peel test using cellophane tape was 90/100 for the former and 95/100 for the latter.

Claims (2)

[Claims] (1) The adhesive surface of a molded article made of polyolefin or a composition of polyolefin and an olefinic polymer compound having a polar group is treated with corona discharge treatment or flame treatment, and the surface wetting tension of the adhesive surface is 38 dynes/i or more 65 After the surface is treated to dyne/d or less, a radiation-curable resin composition is applied to the surface. A method for applying a light- or radiation-curable resin composition to a polyolefin resin molded article. (2) The adhesive surface of a molded product made of a polyolefin or a composition of this polyolefin and an olefinic polymer compound having a polar group is subjected to corona discharge treatment or flame treatment to increase the surface wetting tension of the adhesive surface. 38 dynes/d or more6
5 dynes/- or less, and as a vehicle, the general formula -X, -0COR, -COOR, -OR. Bibon' means 0.01 to 90% by weight of at least one type of olefinic polymer compound having at least one polar group represented by ■ or a hydrocarbon group having 1 to 8 carbon atoms.
A primer solution containing the following is applied as an undercoat, dried, and then a light- or radiation-curable resin composition is applied to the surface.The coated surface has excellent scratch resistance, hardness, and adhesion (peel strength). A method for applying a light- or radiation-curable resin composition to a polyolefin molded article.