JPH07247381A - Coating agent - Google Patents

Abstract

PURPOSE:To improve adherence to a polyolefin substrate which has not been treated with a chlorinated solvent and to a topcoating by using a chlorination product of a specific modified polyolefin. CONSTITUTION:A polyolefin obtained by the thermal degradation of a high-mol. wt. polymer of a 2-20C olefin, having a number-average mol.wt. or 1,000-50,000, and having double bonds at the molecular ends, with the number of double bonds being 0.5 or larger per 1,000 carbon atoms, is reacted with an unsaturated carboxylic acid (anhydride) with heating in a solution or melt state optionally in the presence of an organic peroxide to cause the acid (anhydride) to add to the terminals of the polymer molecules. The resulting modified low-mol. polyolefin is reacted with a low-mol. diol and/or a low-mol. alkanolamine, e.g. monoethanolamine, and the dissolved in a chlorinated solvent under an increased or ordinary pressure. Thus, a chlorinated polyolefin having a bonded-chlorine content of 5-70wt.% is obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a coating agent. More specifically, it relates to a coating agent suitable for coating a polyolefin-based molded product.

[0002]

2. Description of the Related Art When coating a conventional polyolefin-based molded product, the surface of the polyolefin-based molded product is treated with a chlorine-based solvent such as tetrachloroethylene and then modified with a chlorinated polyolefin such as chlorinated polypropylene or its unsaturated carboxylic acid modification. Thing alone or acrylic resin,
A method is known in which a primer is treated with a resin solution used in combination with another resin such as an epoxy resin or a urethane resin.

[0003]

However, recently,
From the viewpoint of environmental protection, the use of chlorine-based solvents is being regulated, and conventional solvent cleaning is shifting to water cleaning. In that case, sufficient adhesion to both the polyolefin-based substrate and the top coating cannot be obtained by the primer treatment with these resin solutions. An object of the present invention is to provide a coating agent which is excellent in adhesion to both a polyolefin-based base material which is not treated with a chlorine-based solvent and a top coating material.

[0004]

Means for Solving the Problems The present inventors have completed the present invention as a result of intensive studies to find a coating agent that achieves the above object. That is, the present invention relates to an unsaturated carboxylic acid or an anhydride-modified low molecular weight polyolefin (a
For a polyolefin-based molded article comprising a chlorinated product (A) of a modified polyolefin obtained by reacting 1) with a low-molecular diol (a2) and / or a low-molecular compound (a3) having a hydroxyl group and an amino group in the molecule. It is a coating agent.

Examples of the low molecular weight polyolefin before modification constituting (a1) in the present invention include homopolymers or copolymers of α-olefins having 2 to 20 carbon atoms, and specific examples are as follows. A different polyolefin resin is used. Further, these peroxide-treated products are also included. Polyethylene (low-pressure method, medium-low pressure method, high-pressure method may be used) Copolymer of ethylene and 15 mol% or less of other α-olefin or vinyl monomer such as vinyl acetate or ethyl acrylate Polypropylene Propylene and 15 mol% or less Random copolymer with other α-olefins Block copolymer with propylene and other α-olefins at 30 mol% or less 1-butene homopolymer 1-butene and other α-olefins at 10 mol% or less Random copolymer 4-methyl-1-pentene homopolymer 4-methyl-1-pentene and other α of 20 mol% or less
-Random Copolymer with Olefin Examples of the above α-olefin include ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like. Among these, preferred is a copolymer containing propylene as a main component. The number average molecular weight of the low molecular weight polyolefin is preferably 1,000 to 50,000, more preferably 2,000 to 20,000. These low molecular weight polyolefins may be obtained by a method of thermally degrading a high molecular weight polyolefin, or may be obtained by ordinary telomerization (a single olefin or a copolymer of olefins). Those having a double bond at the terminal obtained are preferable. The amount of double bonds of the low molecular weight polyolefin used is not particularly limited, but the amount is preferably 0.5 or more per 1000 carbon atoms, and more preferably 1.5 or more at the terminal.

The unsaturated carboxylic acids or their anhydrides constituting (a1) include acrylic acid, methacrylic acid, crotonic acid, maleic acid, cinnamic acid, itaconic acid, citraconic acid, fumaric acid; and maleic anhydride. Examples thereof include unsaturated carboxylic acid anhydrides such as itaconic anhydride and citraconic anhydride, and among these, carboxylic anhydride is particularly preferable.

The modification of the polyolefin with the unsaturated carboxylic acid or its anhydride can be carried out by a known method using a heat reaction or an organic peroxide. As the organic peroxide, those generally used as an initiator in radical polymerization can be used, and the kind thereof is not particularly limited, but one having a half-life of 1 minute or more of 100 ° C. or more is preferable.
Specifically, a ketone peroxide such as 1,1-bis-iso-butylperoxo-3,3,5-trimethylcyclohexane; a dialkyl peroxide such as dicumyl peroxide; a diacyl such as benzoyl peroxide. Peroxide; Peroxyesters such as 2,5-dimethyl-dibenzoylperoxyhexane; 2,
Examples thereof include hydroperoxides such as 5-dimethylhexane-2,5-hydroperoxide.

As a method for producing the unsaturated carboxylic acid or its anhydride-modified low molecular weight polyolefin (a1), any known method such as a solution method and a melting method can be used. In the solution method, it can be obtained by dissolving a polyolefin and an unsaturated carboxylic acid in an organic solvent and heating with or without adding an organic peroxide. Examples of the organic solvent used include hydrocarbons having 6 to 12 carbon atoms and 6 to 12 carbon atoms.
Twelve halogenated hydrocarbons and the like can be used.
The reaction temperature is preferably a temperature at which the polyolefin used is dissolved. In the melting method, polyolefin and unsaturated carboxylic acid are kneaded in the presence or absence of an organic peroxide,
It can be obtained by melt-mixing and reacting.
This can be carried out with an extruder, a Brabender, a kneader, an intensive mixer, a plastomill, etc., and the kneading temperature is not lower than the melting point of the polyolefin to be used or 30.
A temperature range of 0 ° C. or lower is preferable.

The position of addition of the unsaturated carboxylic acid or its anhydride in (a1) may be at the molecular end or inside the molecule, but in order to further enhance the effect of adhesion to the polyolefin-based substrate, the molecular end may be added. Preferably there is. Therefore, the polyolefin before modification is preferably one obtained by thermally degrading a high molecular weight polyolefin having a double bond at the terminal.

Examples of the low molecular weight diol (a2) to be reacted with the (a1) include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 3-methylpentadiol and 1,6-hexanediol. , Neopentyl glycol, bishydroxyethoxybenzene and the like. Examples of the low molecular weight compound (a3) having a hydroxyl group and an amino group in the molecule include monoethanolamine, diethanolamine, 3-amino-1-propanol, 4-amino-1-butanol, aminophenol, aminocresol, aminobenzyl alcohol. , Alkanolamines such as aminophenylethyl alcohol. Of these, preferred are low molecular compounds having a hydroxyl group and an amino group in the molecule, and particularly preferred is monoethanolamine.

For the reaction of (a1) with (a2) or (a3), the above-mentioned solution method or melting method can be similarly used. However, organic peroxide is not used.

The method for chlorinating the modified polyolefin to obtain (A) may be an ordinary method, for example, 90 to 150 by dissolving under pressure or normal pressure in a chlorine-based solvent such as carbon tetrachloride, chloroform or tetrachloroethylene. ℃
Then, a method of injecting chlorine gas in the presence of the above-mentioned peroxide or ultraviolet rays can be mentioned.

The bound chlorine content of the chlorinated product (A) of the modified polyolefin is usually 5 to 70% by weight, preferably 1
5 to 45% by weight. If the amount of bound chlorine is less than 5% by weight, the adhesion to the polyolefin-based molded product will be insufficient, and 7
If it exceeds 0% by weight, the weather resistance of the coating film is deteriorated.

In the coating agent of the present invention (A)
Besides, an organic solvent is usually blended. Examples of the organic solvent include aromatic hydrocarbon solvents (toluene, xylene, etc.), ketone solvents (methyl ethyl ketone, methyl isobutyl ketone, etc.), ester solvents (ethyl acetate, n-butyl acetate, octyl acetate, etc.), cyclic ethers. System solvents (1,4-dioxane, tetrahydrofuran, etc.),
Formamide solvent (N, N-dimethylformamide, etc.), alcohol solvent (methyl alcohol, ethyl alcohol, isopropyl alcohol, etc.), polyhydric alcohol derivative (ethylene glycol monoethyl ether, etc.), (A) The same solvent as above and a mixed solvent of two or more kinds of them can be used. Of these, particularly preferred are aromatic hydrocarbon solvents. The amount is such that the solid content of the coating agent of the present invention is usually 5 to 50% by weight, preferably 10 to 45% by weight.

The coating agent of the present invention is generally used as a vehicle for paints such as melamine resin, acrylic resin and alkyd resin for the purpose of improving solvent resistance, water resistance and smoothness of the coating film, if necessary. The resin may be appropriately mixed. Examples of these resins include those described in "Synthetic Resin Paint" (edited by Kobunshi Publishing Co., Ltd., issued December 10, 1966). When mixed, the resin solid content is usually 50% or less, preferably 35% or less, based on the weight of (A).

The coating agent of the present invention may be blended with usual paint additives such as pigments, dispersants and anti-sagging agents. The amount thereof is usually 100 parts by weight or less, preferably 70 parts by weight or less based on 100 parts by weight of the solid content of the coating agent of the present invention.

As a base material to which the coating agent of the present invention is applied, a polyolefin-based molded product (particularly a molded product mainly containing a propylene-based polymer) is suitable. In addition, it can be used for other plastic molded products, wood, paper, metal, and the like. The coating agent of the present invention may be applied to a substrate by a usual method, for example, the coating agent of the present invention may be applied to a substrate as an object by a coating method such as brush coating, spraying or dipping. The coating amount is usually 5 to 50 μm as a dry film thickness. Usually 5-20 after application
After setting at room temperature for minutes, it is further dried at room temperature or by heating. In the case of room temperature drying, it is usually carried out for 3 to 5 days, and in the case of heat drying, it is usually carried out at 70 to 130 ° C. for 10 to 45 minutes. The application can be carried out by applying it once to the substrate, or by applying it on the wet-on-wet or the applied and dried coating film (more than twice application).

A topcoat is usually applied to the coating film thus coated and dried. The topcoat may be thermoplastic or thermosetting, and examples thereof include commonly used paints such as acrylic, alkyd, urethane, epoxy, melamine alkyd, and acrylic urethane. As these paints, those described in the above "Synthetic resin paint" can be used. It is also possible to apply the top coat agent or the coating agent of the present invention to the substrate and then apply it wet-on-wet.

[0019]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. "Parts" and "%" in the examples represent parts by weight and% by weight, unless otherwise specified. The test methods and measurement methods in the performance test examples are as follows. Gloss: The 60 ° specular reflectance was measured on the coating surface of each coated plate. Initial adhesion: JIS K5 for the coating surface of each coated plate
A cellophane tape test according to 400 was performed. Water-resistant adhesion: Each coated plate was immersed in warm water at 40 ° C. for 240 hours and then taken out to carry out a scoring tape test. Gasohol resistance: Each coated plate was immersed in a mixed solvent of 90 parts of regular gasoline and 10 parts of ethyl alcohol at room temperature for 1 hour, and the appearance of the coating film was observed.

Production Example 1 Maleic anhydride 5 parts, molecular weight 15,000, density 0.8
9. Polypropylene oligomer 1 obtained by thermal decomposition of 1.6 double end bonds (per 1000 carbon atoms)
00 parts was dissolved in xylene and reacted in the presence of dicumyl peroxide to obtain a maleic anhydride-modified polypropylene having a maleic anhydride content of 4.5%. Further, this maleic anhydride-modified polypropylene and monoethanolamine were reacted in xylene and the solvent was removed to obtain a modified polyolefin. Then, this modified polyolefin 10
Dissolve 0 parts in 900 parts tetrachloroethylene and
60 parts of chlorine gas was aerated at 0 to 110 ° C. in the presence of ultraviolet rays. This chlorinated product was dropped into a large amount of methanol to precipitate a resin, which was further washed with methanol, filtered and dried. The bound chlorine content of this reaction product was 18%. 20 parts of this reaction product was dissolved in 80 parts of toluene to obtain a chlorinated product solution (P-1) of modified polypropylene.

Production Example 2 A reaction product having a combined chlorine content of 27% was obtained in the same manner as in Production Example 1 except that the gas flow rate of chlorine gas was changed to 100 parts. 20 parts of this reaction product was dissolved in 80 parts of toluene to obtain a chlorinated product solution (P-2) of modified polypropylene.

Examples 1 and 2 and Comparative Example 1 Chlorinated chloride solutions (P-1) to (P-2) of the modified polypropylene obtained in Production Examples 1 and 2, toluene and titanium oxide in the proportions shown in Table 1. After mixing, the coating agent (C-1) of the present invention is kneaded for one day in a ball mill.
(C-2) was obtained. Further, in place of the chlorinated product of the modified polypropylene, a 20% toluene solution of chlorinated polypropylene (“Super Clone 822”, made by Nippon Paper Industries), toluene and titanium oxide are mixed in the proportions shown in Table 1 and then kneaded in the same manner. According to the comparison coating agent (H-1)
Got

[0023]

[Table 1]

Performance Test Example A propylene-ethylene block copolymer injection-molded plate (thickness: 2 mm) having an ethylene content of 6 mol% was prepared, and the surface thereof was washed with water and air-dried, and then, Examples 1 and 2 and Comparative Example were compared. The coating agent of Example 1 was applied to the injection-molded board by spraying. After setting at room temperature for 5 minutes, it was dried at 120 ° C. for 10 minutes by a circulating air dryer (dry film thickness: about 10 μm). A commercially available melamine alkyd-based topcoat (“Flexen # 10
1 ", made by Nippon Bee Chemical Co., Ltd. with thinner (# 101-)
It was diluted to 2: 1 (weight ratio) with 10), applied by spraying, set at room temperature for 15 minutes, and baked at 120 ° C for 30 minutes with a circulating air dryer (dry film thickness;
About 40 μm). Each test was performed on each coating film thus obtained. The test results are shown in Table 2.

[0025]

[Table 2]

[0026]

The coating agent of the present invention has the following effects. (1) Excellent adhesion to both the polyolefin-based base material whose surface is not washed with a chlorine-based solvent and the top coat agent. (2) A coating film having good water resistance and solvent resistance can be obtained. (3) The pigment dispersibility is also good, and a coating film having good smoothness is provided. Since the above-mentioned effects are exhibited, the coating agent of the present invention is suitably used as a coating agent for polyolefin-based molded products, particularly propylene-based polymer molded products (such as automobile bumpers), as well as adhesives and printing inks for these molded products. It is also preferably used as a vehicle. In addition, coating materials such as plastics other than polyolefin, wood, paper, metal, etc.
It can also be used as a vehicle for adhesives and printing inks.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hajime Akiyama 1 1-11, Hitotsubashi-honmachi, Higashiyama-ku, Kyoto Sanyo Chemical Industry Co., Ltd.

Claims (4)

[Claims] 1. An unsaturated carboxylic acid or its anhydride-modified low molecular weight polyolefin (a1) is reacted with a low molecular diol (a2) and / or a low molecular compound (a3) having a hydroxyl group and an amino group in the molecule. A coating agent for a polyolefin-based molded article, which comprises the chlorinated product (A) of a modified polyolefin obtained as described above. 2. The polyolefin before modification constituting (a1) is a heat-reduced low molecular weight polyolefin.
The coating agent described. 3. (a1) is a modified low molecular weight polyolefin obtained by modifying the molecular chain end of a low molecular weight polyolefin with an unsaturated carboxylic acid or an anhydride thereof.
Or the coating agent according to 2. 4. The coating agent according to claim 1, wherein the content of bound chlorine in (A) is 5 to 70% by weight.