JP2007100010A - Aqueous primer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous primer that exerts good adhesion to a polyolefin resin without incorporating a chlorine-containing resin. <P>SOLUTION: This aqueous primer comprises an acid modified polyolefin resin (A) and/or its salt that is prepared by graft polymerizing at least one selected from the group consisting of an unsaturated dicarboxylic acid, its anhydride and its ester derivative to a polyolefin resin, and has a mass average molecular weight more than 20,000 and an acid value of 4 mg KOH/g or more. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aqueous primer that does not contain a chlorine-containing resin.

  Plastic is used as a material for automobile parts such as interior parts. Recently, applications have expanded to functional parts in engine rooms, automotive electronics systems, fuel systems, etc., making them indispensable materials for automobile manufacturing. Conventionally, polyvinyl chloride resin has been widely used as a plastic for automobile parts, but it has decreased due to the recent increase in interest in environmental problems, and recently, polypropylene resin has been frequently used.

  Polypropylene resin is suitable for automobile parts because it is inexpensive and has excellent moldability, light weight, chemical resistance, recyclability, and the like. Recently, elastomer-modified polypropylene resins having improved low-temperature impact properties, releasability and the like have been developed, and the use of polypropylene resins tends to be further expanded.

  However, polypropylene resin is a difficult-to-paint material, and there is a problem that sufficient adhesion cannot be obtained with conventional paints. By coating the surface of the polypropylene resin after corona discharge, the adhesion of the paint can be improved, but the process becomes complicated and there are many problems in terms of cost.

  Therefore, in order to solve the problem of the adhesion of the paint to the polypropylene resin, a primer for a polyolefin resin containing a chlorinated polyolefin polymer as an active ingredient has been proposed (Patent Documents 1 and 2). By using the primer, the adhesion of the paint to the polyolefin resin is improved.

However, the primer is mainly composed of a chlorine-containing resin called chlorinated polyolefin. Recently, a primer that does not contain a chlorine-containing resin has been desired from the viewpoint of generation of chlorine gas during incineration, recyclability, and the like.
Japanese Patent No. 3543975 Japanese Patent No. 3383980

  Therefore, the objective of this invention is providing the water-based primer which exhibits the favorable adhesiveness with respect to polyolefin resin, without containing chlorine containing resin.

The aqueous primer of the present invention has a mass average molecular weight of more than 20000 and an acid value of 4 mgKOH / in which at least one selected from the group consisting of unsaturated dicarboxylic acids, anhydrides and ester derivatives thereof is graft-polymerized to a polyolefin resin. g or more acid-modified polyolefin resin (A) and / or a salt thereof.
The acid-modified polyolefin resin (A) is preferably an acid-modified polypropylene resin.

The aqueous primer of the present invention further contains an anionic surfactant (B) and / or an organic acid that is neutralized to become an anionic surfactant, and the anionic surfactant (B) and the organic acid The total amount is preferably 1 to 20 parts by mass with respect to 100 parts by mass in total of the acid-modified polyolefin resin (A) and its salt.
The water-based primer of the present invention has a water content of 3 to 90% by mass, and the acid-modified polyolefin resin (A) and / or a salt thereof is preferably dispersed in water.

  The aqueous primer of the present invention exhibits good adhesion to a polyolefin resin without containing a chlorine-containing resin.

<Acid-modified polyolefin resin (A) and its salt>
The acid-modified polyolefin resin (A) is obtained by graft-polymerizing at least one selected from the group consisting of an unsaturated dicarboxylic acid, an anhydride thereof and an ester derivative onto a polyolefin resin.

Examples of the polyolefin resin include a low density polyethylene resin, a high density polyethylene resin, a polypropylene resin, and an ethylene / vinyl acetate copolymer. As the polyolefin resin, a polypropylene resin is preferable from the viewpoint of storage stability and adhesion of the aqueous primer.
Examples of the polypropylene resin include propylene homopolymers; copolymers of propylene and one or more selected from the group consisting of ethylene, other α-olefins, and vinyl compounds. Other α-olefins are preferably α-olefins having 4 to 18 carbon atoms, such as 1-butene, isobutene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene and the like can be mentioned. As the polypropylene resin, a propylene homopolymer is particularly preferable from the viewpoint of adhesion of the aqueous primer.
Polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

Examples of the unsaturated dicarboxylic acid include maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid and the like. Examples of the unsaturated dicarboxylic acid anhydride include maleic anhydride, itaconic anhydride, and citraconic anhydride. Examples of the ester derivative of unsaturated dicarboxylic acid include monomethyl maleate. Of these, anhydrides of unsaturated dicarboxylic acids are preferred, and maleic anhydride is particularly preferred from the viewpoint of stability of emulsification during production.
Unsaturated dicarboxylic acid, its anhydride, or ester derivative may be used individually by 1 type, and may use 2 or more types together.

  The mass average molecular weight of the acid-modified polyolefin resin (A) is more than 20000, preferably more than 20000 and not more than 150,000, and more preferably 25,000 to 120,000. When the mass average molecular weight of the acid-modified polyolefin resin (A) exceeds 20000, adhesion to the polyolefin resin is sufficiently exhibited. By setting the mass average molecular weight of the acid-modified polyolefin resin (A) to 150,000 or less, the enlargement of the acid-modified polyolefin resin (A) particles in the aqueous primer is suppressed, and the storage stability of the aqueous primer is improved.

  The acid value of the acid-modified polyolefin resin (A) is 4 mgKOH / g or more, preferably 4 to 200 mgKOH / g, more preferably 10 to 160 mgKOH / g. By setting the acid value of the acid-modified polyolefin-based resin (A) to 4 mgKOH / g or more, the adhesiveness between the aqueous primer and the topcoat paint, adhesive, etc. is improved. By setting the acid value of the acid-modified polyolefin resin (A) to 200 mgKOH / g or less, a decrease in the dispersion rate of the acid-modified polyolefin resin (A) in water can be suppressed.

  The acid-modified polyolefin resin (A) is produced by graft polymerization of an unsaturated dicarboxylic acid, its anhydride or ester derivative to a polyolefin resin according to a conventional method.

The acid-modified polyolefin resin (A) may be a salt neutralized with a basic substance. As will be described later, the acid-modified polyolefin resin (A) may be present as a salt of the acid-modified polyolefin resin (A) by adding a basic substance during the preparation of the aqueous primer.
In the aqueous primer, the acid-modified polyolefin resin (A) and a salt thereof may be simultaneously present.

<Anionic surfactant (B), an organic acid that is neutralized to become an anionic surfactant>
An anionic surfactant (B) and an organic acid that is neutralized to become an anionic surfactant (hereinafter referred to as an organic acid) are prepared by converting the acid-modified polyolefin resin (A) and / or a salt thereof into a solid fine particle. It is dispersed in water as particles.

  Examples of the anionic surfactant (B) include primary higher fatty acid salts, secondary higher fatty acid salts, primary higher alcohol sulfates, secondary higher alcohol sulfates, and primary higher alkyl sulfonic acids. Salts, secondary higher alkyl sulfonates, higher alkyl disulfonates, sulfonated higher fatty acid salts, higher fatty acid sulfate esters, higher fatty acid ester sulfonates, higher alcohol ether sulfonates, higher fatty acid amide alkylols And sulfuric acid ester salts, alkylbenzene sulfonates, alkylphenol sulfonates, alkylnaphthalene sulfonates, and alkylbezoimidazole sulfonates.

The anionic surfactant (B) is preferably a higher fatty acid salt, more preferably a saturated or unsaturated higher fatty acid salt having 10 to 20 carbon atoms, particularly an alkali metal salt, from the viewpoint of emulsion stability during production. preferable. Specifically, alkali metal salts of saturated fatty acids such as capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, and arachidic acid; Examples thereof include alkali metal salts of unsaturated fatty acids such as linoleic acid, linolenic acid, and arachidonic acid.
An anionic surfactant (B) may be used individually by 1 type, and may use 2 or more types together.

  Organic acids include primary higher fatty acids, secondary higher fatty acids, primary higher alcohol sulfates, secondary higher alcohol sulfates, primary higher alkyl sulfonic acids, secondary higher alkyl sulfonic acids, higher Alkyl disulfonic acid, sulfonated higher fatty acid, higher fatty acid sulfate ester, higher fatty acid ester sulfonic acid, sulfonic acid of higher alcohol ether, alkylolated sulfate ester of higher fatty acid amide, alkylbenzene sulfonic acid, alkylphenol sulfonic acid, alkylnaphthalene sulfonic acid, Examples thereof include alkylbezoimidazolesulfonic acid.

As the organic acid, a higher fatty acid is preferable from the viewpoint of dispersibility and adhesion, and a saturated or unsaturated higher fatty acid having 10 to 20 carbon atoms is particularly preferable. Specifically, saturated fatty acids such as capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, and arachidic acid; lindenic acid, tuzuic acid, petroceric acid, oleic acid, linoleic acid, linolenic acid Examples thereof include unsaturated fatty acids such as acids and arachidonic acid.
An organic acid may be used individually by 1 type, and may use 2 or more types together.
Moreover, you may use together an anionic surfactant (B) and an organic acid.

  The total of the anionic surfactant (B) and the organic acid is preferably 1 to 20 parts by mass, and 5 to 15 parts by mass with respect to 100 parts by mass in total of the acid-modified polyolefin resin (A) and its salt. It is more preferable that By setting the total of the anionic surfactant (B) and the organic acid to 1 part by mass or more, the emulsification characteristics are improved, and the non-emulsified product in the aqueous primer is suppressed. By making the total of the anionic surfactant (B) and the organic acid 20 parts by mass or less, a decrease in adhesion to the polyolefin resin can be suppressed.

<Other ingredients>
The aqueous primer of the present invention may contain a low molecular weight acid-modified polyolefin (co) polymer excluding the acid-modified polyolefin resin (A) in order to reduce the particle size of the solid content in the aqueous primer.
Examples of the polyolefin (co) polymer include ethylene homopolymers, propylene homopolymers; copolymers of propylene and one or more selected from the group consisting of ethylene, other α-olefins, and vinyl compounds. Other α-olefins are preferably α-olefins having 4 to 18 carbon atoms, such as 1-butene, isobutene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene and the like can be mentioned. The polyolefin (co) polymer is preferably a propylene homopolymer from the viewpoint of storage stability and adhesion of the aqueous primer.

  The aqueous primer of the present invention may contain other resins as long as the effects of the present invention are not impaired. Other resins include rubbers such as ethylene-α-olefin copolymer, polyisobutylene, butyl rubber, styrene-butadiene copolymer rubber, nitrile rubber, and silicone rubber; other than thermoplastic resins such as polyurethane, epoxy resin, and melamine resin And the like.

  You may add the thickener for raising a viscosity, the antifoamer for suppressing foaming, etc. to the aqueous primer of this invention. Examples of the thickener include water-soluble polymers such as carboxymethylcellulose, sodium polyphosphate, polyvinyl alcohol, sodium polyacrylate, ammonia miclecasein, vinyl alcohol-methacrylic acid copolymer, starch, and protein. The addition amount of the thickener is preferably 200 parts by mass or less, and more preferably 100 parts by mass or less, with respect to 100 parts by mass of all resin components in the aqueous primer.

  The aqueous primer of the present invention includes various auxiliary materials such as emulsifiers, dispersants, stabilizers, wetting agents, foaming agents, coagulants, gelling agents, antioxidants, ultraviolet absorbers, hydrochloric acid absorbers, pigments, Dyes, nucleating agents, antiblocking agents, slip agents, antistatic agents, flame retardants, plasticizers, fillers, coloring agents, flavoring agents, antiblocking agents, release agents, etc. may be added as necessary. .

<Water-based primer>
The aqueous primer of the present invention apparently has a solid content dispersed in water as fine particles. Depending on the water content, it may be in a paste state or a dispersed state, but it may be in any state.

  The water content of the aqueous primer of the present invention is preferably from 3 to 90 mass%, more preferably from 35 to 75 mass%, in the aqueous primer (100 mass%). That is, the solid content concentration is preferably 10 to 97% by mass, and more preferably 25 to 65% by mass. When the water content is high and the solid content concentration is low, the adhesion to the polyolefin resin may be insufficient. When the water content is low and the solid content concentration is high, the storage stability of the aqueous primer may decrease.

  The average particle diameter of the fine particles derived from the acid-modified polyolefin resin (A) and / or a salt thereof is preferably 0.01 to 1 μm, more preferably 0.05 to 0.5 μm. When the average particle diameter of the fine particles is too small, it is necessary to increase the amount of the anionic surfactant (B) added, and as a result, the adhesion to the polyolefin resin may be lowered. If the average particle size of the fine particles is too large, the storage stability of the aqueous primer may be reduced.

  The aqueous primer of the present invention is obtained by melt-kneading the acid-modified polyolefin resin (A) and / or a salt thereof, an anionic surfactant (B) and / or an organic acid, and other components as necessary (melt-kneading). Step), the obtained melt-kneaded product can be prepared by adding water and a basic substance to cause phase inversion so that the solid content is dispersed as fine particles in water (phase inversion step).

The basic substance saponifies the non-neutralized acid-modified polyolefin resin (A) and the organic acid when phase inversion is performed so that the solid content is dispersed as fine particles in water. belongs to. Basic substances include substances that act as bases in water such as alkali metals, alkaline earth metals, ammonia and amines; alkali metal oxides, hydroxides, weak bases, hydrides; alkaline earth metal oxides Substances that act as bases in water, such as hydroxides, weak bases, hydrides; alkoxides of these metals.
Although a basic substance may be added directly, it is preferable to add in the state of about 5-40 mass% aqueous solution. The addition amount of the basic substance is preferably 0.4 to 8 parts by mass with respect to 100 parts by mass in total of the acid-modified polyolefin resin (A) and its salt.

The melt-kneading step and the phase inversion step may be performed sequentially or simultaneously.
In the melt kneading step, a known melt kneading means may be used. Examples of the melt-kneading means include a kneader, a Banbury mixer, and a multi-screw extruder.
The prepared aqueous primer is then naturally or artificially cooled to room temperature. At this time, the dispersed particles are solidified and the aqueous primer is stabilized.

<Application>
The aqueous primer of the present invention is a primer that is coated on the surface of a polyolefin resin when a polyolefin resin such as a polyethylene resin or a polypropylene resin is coated, or when a polyolefin resin is bonded to a polyolefin resin or other material. Suitable for Examples of other materials include cloth, fiber, resin, paper, metal, and the like.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples. In the examples, “part” means “part by mass”, and “%” means “% by mass”.

[Example 1]
Preparation of aqueous primer (X-1):
100 parts of an acid-modified polypropylene resin having a mass average molecular weight of 30,000 and an acid value of 52 mgKOH / g (an acid-modified polypropylene resin obtained by graft polymerization of maleic anhydride onto a propylene homopolymer, “Yumex 1010” manufactured by Sanyo Chemical Industries, Ltd.) 10 parts of potassium oleate were mixed. Subsequently, this mixture was supplied to a twin screw extruder (Ikegai Steel Co., Ltd., “PCM-30 type”, L / D = 40) from a hopper at 4 kg / hour, and a potassium hydroxide 20% aqueous solution was supplied thereto. Was continuously kneaded at 720 g / hour, and melted and kneaded at a heating temperature of 200 ° C. to extrude the melt. Subsequently, the melt was continuously supplied to a cooling single screw extruder attached to the tip of the extruder and cooled to 90 ° C. The taken-out solid was thrown into 80 degreeC warm water, and was disperse | distributed continuously, and the aqueous | water-based primer (X-1) of the average particle diameter of solid content 0.22 micrometer and solid content concentration 45% was obtained. The following evaluation was performed about the water-based primer (X-1). The results are shown in Table 1.

(Storage stability)
After the aqueous primer was stored at 50 ° C. for 1 month, the appearance of the aqueous primer was observed. When the appearance was not changed as compared with that before storage, it was evaluated as ○, and when the appearance was changed as ×.
The aqueous primer after storage for 1 month was immersed in a thermostat at 25 ° C. for about 1 hour, and then its pH was measured with a pH meter.
Moreover, the average particle diameter of the solid content in the aqueous primer after storage for 1 month was measured with Microtrac UPA (manufactured by Mountaintech Co., Ltd.).

(Adhesion)
The aqueous primer was spray-coated on a polypropylene resin plate and dried at 80 ° C. for 30 minutes. Next, a two-component urethane-based top coating was applied, left at room temperature for 10 minutes, and dried at 80 ° C. for 30 minutes using a hot air dryer. The obtained coated plate was allowed to stand at room temperature for 1 day and then subjected to the following test.
The surface of the coating film was cut with a cutter to make 100 grids at intervals of 2 mm, and the cellophane adhesive tape was adhered to it and peeled in the direction of 180 degrees, and the number of remaining grids was counted. . If the number of grids that were not peeled off was 100, it was rated as ○.

[Example 2]
Preparation of aqueous primer (X-2):
As an acid-modified polyolefin resin, an acid-modified polypropylene resin having a mass average molecular weight of 40,000 and an acid value of 26 mgKOH / g (an acid-modified polypropylene resin obtained by graft polymerization of maleic anhydride onto a propylene homopolymer, manufactured by Sanyo Chemical Industries, Ltd., Aqueous primer (X-2) was prepared in the same manner as in Example 1 except that 100 parts of Umex 1003 ”) was used and the feed rate of the 20% potassium hydroxide aqueous solution was changed to 360 g / hour. The aqueous primer (X-2) had an average solid particle size of 0.25 μm and a solid content concentration of 45%. The aqueous primer (X-2) was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
Preparation of aqueous primer (X-3):
As acid-modified polyolefin resin, acid-modified polypropylene resin having a weight average molecular weight of 10,000 and an acid value of 3.5 mgKOH / g (acid-modified polypropylene resin obtained by graft polymerization of maleic anhydride to propylene homopolymer, manufactured by Sanyo Chemical Industries, Ltd.) An aqueous primer (X-3) was prepared in the same manner as in Example 1 except that 100 parts of “Umex 100TS” was used and the supply rate of the 20% potassium hydroxide aqueous solution was changed to 50 g / hour. The aqueous primer component (X-3) had an average particle size of solid content of 0.15 μm and a solid content concentration of 45%. The aqueous primer (X-3) was evaluated in the same manner as in Example 1. The results are shown in Table 1.

  From the results of Table 1, it can be seen that according to the aqueous primers of Examples 1 and 2, the coating film exhibits good adhesion to the polyolefin resin.

The aqueous primer of the present invention is useful as a primer for coating a polyolefin resin and a primer for bonding a polyolefin resin to another substrate.

Claims (4)

  An acid-modified polyolefin having a mass average molecular weight of more than 20000 and an acid value of 4 mgKOH / g or more obtained by graft-polymerizing at least one selected from the group consisting of an unsaturated dicarboxylic acid, an anhydride thereof and an ester derivative onto a polyolefin resin. Aqueous primer containing a resin (A) and / or a salt thereof.   The aqueous primer according to claim 1, wherein the acid-modified polyolefin resin (A) is an acid-modified polypropylene resin. An anionic surfactant (B) and / or an organic acid that is neutralized to become an anionic surfactant;
The total of the anionic surfactant (B) and the organic acid is 1 to 20 parts by mass with respect to 100 parts by mass of the total of the acid-modified polyolefin resin (A) and its salt. Or the aqueous primer of 2. The moisture content is 3 to 90% by mass, and the acid-modified polyolefin resin (A) and / or a salt thereof is dispersed in water. Aqueous primer.