JPH07224244A - Primer composition and coating method - Google Patents

Abstract

PURPOSE:To obtain a primer compsn. which enables a thermoplastic olefin elastomer molding to be coated without any surface treatment by compounding a chlorinated polyolefin, an epoxy resin, and a curative. CONSTITUTION:A coating compsn. contains a chlorinated polyolefin having a chlorine content of 10-50wt.%, an epoxy resin (e.g. a bisphenol A-based, a novolac-based, or an aliph. epoxy resin) in an amt. of 10-90wt.% of the chlorinated polyolefin, and a curative in an amt. of 4-100wt.% of the epoxy resin. An amine curative is pref., and a latent curative can also be used. When a microcapsuled curative is used, the compsn. has an enough storage stability. The compsn. is prepd. by dissolving the chlorinated polyolefin in a solvent in a concn. of 10-30wt.% and adding the epoxy resin and the curative to the resulting soln.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primer composition and a coating method useful for coating (painting) the surface of an olefin-based thermoplastic elastomer molded product, which is a substitute material for PVC (vinyl chloride resin).

[0002]

2. Description of the Related Art Conventionally, olefinic thermoplastic elastomers have attracted attention and have come to be used particularly as a part of automobile parts because of their many suitability as materials for automobile parts. . That is, an olefin-based thermoplastic elastomer as an alternative to PVC has flexibility without using a plasticizer like PVC, and can reduce the weight of automobile parts because it has a smaller specific gravity than PVC. The parts of the department are recyclable.

The olefinic thermoplastic elastomer used for automobile parts and the like is mainly composed of a thermoplastic elastomer material composed of ethylene, propylene and EPDM having a partially crosslinked structure, and an antistatic agent for improving various physical properties, A heat stabilizer, an ultraviolet absorber, an extender pigment and the like are blended.

In general, for olefinic thermoplastic elastomer moldings, a primer composition having a very limited composition is used when the surface is top-coated. This is because the critical surface tension of the surface of the molded product is low, that is, the surface is inactive.
Therefore, when coating the surface of an olefin-based thermoplastic elastomer molded product, the surface is physically activated by vaporization of a chlorine-based solvent or plasma treatment such as corona discharge treatment due to its inactive property. At present, it is currently covered with a chlorinated polyolefin-based or saturated polyester-based primer.

[0005]

[Problems to be Solved by the Invention] However, with respect to automobile parts, especially interior parts, there is a trend toward higher quality, and few are completed with only plastic materials. For example, interior materials for doors (door trim) are Most of them are composite materials of plastic material and woven cloth. The formation of these composite materials is performed by combining an adhesive and a high frequency welder.

When a chlorinated polyolefin-based primer is used for coating the surface of an olefin-based thermoplastic elastomer molding, sufficient adhesion can be obtained without physically activating the surface, but chlorinated polyolefin is The melting point is low, and sufficient heat-resistant creep resistance cannot be obtained. For example, when a woven fabric or the like is made into a composite after coating the surface of the molded product, the woven fabric or the like may come off. Further, there is a problem that the film obtained by the primer also has poor solvent resistance.

Further, Japanese Patent Application Laid-Open No. 63-272547 proposes a method of using a saturated polyester and polyisocyanate as a primer. In this method, the surface of an olefinic thermoplastic elastomer molded article is physically activated. If the critical surface tension is not more than 45 dyne, the saturated polyester and the primer composition of the polyisocyanate do not adhere to each other, and the coating work becomes complicated.

Therefore, an object of the present invention is to coat the surface of an olefinic thermoplastic elastomer molded article with the material as it is without physically activating the surface and the adhesion between the surface and the topcoat layer. Solvent resistance is sufficiently obtained, and for a composite material of an olefinic thermoplastic elastomer molded article and a woven fabric or the like, by providing a primer composition and a method for coating the above-described molded article in which heat creep resistance is sufficiently obtained. is there.

[0009]

The above object can be achieved by the present invention described below. That is, the present invention has a chlorine content of 10 to 10.
A primer composition comprising 50% by weight of a chlorinated polyolefin, an epoxy resin and a curing agent, and a method for coating a molded article using the primer composition.

[0010]

[Function] By containing a chlorinated polyolefin having a chlorine content within a specific range as a film-forming component of a primer composition, sufficient adhesion can be obtained with an olefin-based thermoplastic elastomer molding having an inactive surface. . Further, by using a thermosetting epoxy resin in combination with the above chlorinated polyolefin, sufficient solvent resistance and heat creep resistance can be obtained. Therefore, when the primer composition is used for coating a film, a sheet or the like and the embossing is performed, the embossing is smoothly performed for the above reason, and a film or a sheet having excellent antiglare property and design is provided. Can be done.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. The primer composition of the present invention contains a chlorinated polyolefin having a chlorine content of 10 to 50% by weight. When the content is less than 10% by weight, the adhesion to the object to be coated is insufficient, while when the content exceeds 50% by weight, flexibility and strength as a primer are insufficient, which is not preferable. The chlorinated polyolefin may be a chlorinated polyolefin modified to further contain a carboxyl group or the like in an amount of about 1 to 5% by weight,
The presence of the carboxyl group further improves the adhesion to the surface of the molded product.

The primer composition of the present invention contains an epoxy resin as a crosslinking medium. Examples of this epoxy resin include a general bisphenol A type epoxy resin, a novolac type epoxy resin, and an aliphatic epoxy resin. The epoxy resin is contained in an amount of 10 to 90% by weight with respect to the chlorinated polyolefin, preferably 20 to 50% by weight is blended. If it is less than 10% by weight, the effect of improving adhesion, heat resistance, solvent resistance, etc. with respect to the object to be coated is insufficient, while if it exceeds 90% by weight, the coating film made of the primer composition becomes too hard and flexible. Is insufficient, the top coat layer cannot follow when the coated molded article is bent, etc., which causes cracks and the like in the top coat layer.

Further, the primer composition of the present invention contains a curing agent for the above epoxy resin. As the curing agent, any conventionally known curing agent for epoxy resin can be used, but an amine-based curing agent is preferably used. Specific examples of the amine-based curing agent include, for example, aliphatic polyamines,
Examples include amines such as aromatic polyamines, dicyandiamide, and imidazole compounds. A known latent curing agent can be used as the curing agent other than the amine-based curing agent.

Specific examples of the latent curing agent include, for example,
Examples thereof include BF ₃ complex, imidazole derivative, diaminomaleonitrile and its derivative, polyamine salt, carboxylic acid ester, methylhydrazine, amineimide compound, aromatic diazonium salt, and diaryliodonium salt. The addition amount of these curing agents is preferably in the range of 4 to 100% by weight with respect to the epoxy resin. If the added amount is less than 4% by weight, the curing of the epoxy resin is insufficient, and if it exceeds 100% by weight, the epoxy resin is over-cured and the flexibility of the formed coating film decreases,
This will cause cracks in the top coat layer and the like.

Here, when it is necessary for the primer composition of the present invention to have sufficient storage stability due to operational problems, the curing agent added to the primer composition is microencapsulated to ensure sufficient storage. Stability is obtained. As a method of microencapsulating the curing agent, an interfacial polymerization method,
Any conventionally known method such as coacervation can be used. The primer composition of the present invention is prepared by dissolving the above-mentioned chlorinated polyolefin in a solvent for chlorinated polyolefin such as an aromatic type or a ketone type at a concentration of 10 to 30% by weight to obtain the predetermined amount of the epoxy resin and the curing agent. It can be manufactured by sequentially adding and stirring sufficiently. At this time, if necessary, an ultraviolet absorber, an antioxidant, and an extender pigment may be blended. If the solution concentration of the chlorinated polyolefin is less than 10% by weight, the cost of the solvent is high, while if it exceeds 30% by weight, the applicability may become a problem due to an increase in viscosity.

As the method for applying the primer composition of the present invention to the surface of the resin molded article, any conventionally known application method such as spraying, roll coating, gravure roll coating and gravure coating can be used. The object to be coated to which the primer composition of the present invention is applied is generally a resin molded product, but a film, sheet and three-dimensional film made of the above-mentioned olefinic thermoplastic elastomer exerts a particularly excellent effect. Molded articles and the like. As a drying method after coating the primer composition of the present invention, conventionally known methods are used, but the solvent in the primer composition is sufficiently volatilized, and the chlorinated polyolefin in the primer composition, an epoxy resin and Any condition may be used as long as the reaction of the curing agent is completed.

The coating method of the present invention is characterized in that the primer composition as described above is applied to the surface of an olefinic thermoplastic elastomer molded article and dried, and then a topcoat layer is formed thereon. In the coating method of the present invention, any surface treatment agent (top coat agent, paint) can be applied to the coating surface made of the above primer composition. As these surface treatment agents, any conventionally known surface treatment agents can be used, but preferable surface treatment agents include, for example, polyurethane-based, polyvinyl chloride-based and acrylic ester-based surface treatment agents. These surface treatment agents may be transparent clear,
It may be an opaque or colored surface treatment agent containing any additive such as various extender pigments and coloring pigments. The coating method and the drying method of the surface treatment agent are the same as the coating method and the drying method of the primer.

The surface of the coated olefinic thermoplastic elastomer molded product obtained as described above may be embossed if necessary. The embossing treatment is to give unevenness to the surface in order to enhance anti-slip properties, anti-glare properties, etc. Normally, an embossing roll for heating gives unevenness of various sizes to provide anti-slip properties and anti-glare properties. In addition to the above, a matte surface or a leather-like grain pattern can be optionally provided.

[0019]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, “part” or “%” is based on weight unless otherwise specified. Example 1 92.8 parts of a toluene solution of a chlorinated polyolefin having a chlorine content of 25% (resin solid content 20%), 2 parts of silicic acid anhydride,
5 parts of a bisphenol A type epoxy resin having an epoxy equivalent of 180 to 190 and 0.2 part of 2-ethyl-4-methyl-imidazole were sequentially added and sufficiently stirred to prepare a primer composition of the present invention.

Example 2 92.8 parts of a toluene solution of a chlorinated polyolefin having a chlorine content of 25% (resin solid content 20%), 2 parts of silicic acid anhydride,
5 parts of a bisphenol A type epoxy resin having an epoxy equivalent of 180 to 190 and 1.0 part of a capsule type imidazole were sequentially added and sufficiently stirred to prepare a primer composition of the present invention.

Example 3 Carbonate polyol having a molecular weight of 1,000 to 3,000, 1,3-butanediol as a chain extender, and isophorone diisocyanate (IPD) as an isocyanate component.
Using I), the mixture was thoroughly stirred in a solvent system of toluene-isopropyl alcohol (weight ratio 1: 1) to synthesize a polycarbonate-based polyurethane resin varnish having a nonvolatile content of 30% and a molecular weight of 50,000 to 100,000.

A surface treating agent comprising 30 parts of the above polycarbonate-based polyurethane resin varnish, 2 parts of silicic acid anhydride, 20 parts of toluene, 20 parts of isopropyl alcohol and 28 parts of methyl ethyl ketone was prepared. The primer composition of Example 1 was applied once to a sheet surface made of an olefinic thermoplastic elastomer with a 120-mesh gravure roll and dried at 70 ° C. for 60 seconds, and then the surface treatment agent was applied to a 120-mesh gravure roll. And apply twice, 7
It was dried at 0 ° C. for 60 seconds. Further, the surface of the molded product is 180
Embossing treatment was carried out at a temperature of from ℃ to 200 ℃ to obtain a coated olefin-based thermoplastic elastomer molded product by the coating method of the present invention.

Example 4 Example 4 was repeated except that the primer composition of Example 1 was replaced with the primer composition of Example 2.
A molded product of the coated olefinic thermoplastic elastomer was obtained by the coating method of the present invention. Comparative Example 1 To 98 parts of a toluene solution of a chlorinated polyolefin having a chlorine content of 25% (resin solid content: 20%), 2 parts of silicic acid anhydride was added and sufficiently stirred to prepare a primer composition of a comparative example.

Comparative Example 2 The procedure of Example 3 was repeated, except that the primer composition of Example 1 was replaced with the primer composition of Comparative Example 1.
A coated olefinic thermoplastic elastomer molded article was obtained by the coating method of Comparative Example.

Evaluation 1 The following various physical properties of the coated olefinic thermoplastic elastomer moldings of Examples 3 to 4 and Comparative Example 2 were measured. The results are shown in Table 1 below. Cross-cut primary adhesion test JIS K 5400 Surface treatment agent General test method 6.
According to item 15, cuts that penetrate the coating on the surface of the coated moldings of Examples 3 to 4 and Comparative Example 2 and reach the original plate,
11 cutters are formed at intervals of 2 mm with a cutter, and 11 cuts are further made orthogonal to this to make a grid pattern. After the cellophane tape is pressure-bonded to the cross-cut part, the cellophane tape is vigorously peeled off. The evaluation shows the number of peeled pieces in 100 cut squares as follows. Example) There is no peeled top coat layer. 100/100 30 squares were peeled off. 70/100 All were peeled off. 0/100

Solvent resistance test The surface condition of the coated moldings of Examples 3 to 4 and Comparative Example 2 after being strongly wiped with a flannel cloth containing industrial gasoline was examined. The evaluation criteria are as shown below. Grade 5 No abnormalities are observed. Grade 4 Some traces such as whitening of the top coat layer are seen. Peeling of Part 3 topcoat layer is observed. Heavy whitening and peeling of the second-class topcoat layer are observed. The first-class topcoat layer was completely peeled off.

Heat creep resistance test Polyester urethane adhesive was used as an adhesive, and polyisocyanate was blended at an arbitrary ratio as a curing agent,
The adhesive was applied to the surface of the coated moldings of Examples 3 to 4 and Comparative Example 2 using a bar coater at a rate of 80 g / m ² (wet) and dried at 80 ° C. for 2 minutes. After that, the adhesive surfaces of the coated moldings are bonded to each other with a laminator at a roll temperature of 100 ° C., and left at 40 ° C. for 2 days to complete the reaction of the adhesive. The sample is left in the thermostatic chamber with a load of 500 g / 2.5 cm in the direction perpendicular to the bonding surface. The temperature was raised from 40 ° C. to 10 ° C. every 60 minutes, and the upper limit temperature at which the top coat layer was not peeled off was measured.

[0028]

[Table 1]

Evaluation 2 The following physical properties of the primer compositions of Examples 1 and 2 and Comparative Example 1 were measured. The results are shown in Table 2 below. Pot life (storage stability) test 10 times the primer compositions of Examples 1-2 and Comparative Example 1
The sample was left to stand under the respective temperature conditions of 30 ° C., 30 ° C. and 50 ° C. at the same time, and the state change of the solution was observed. The evaluation criteria are as shown below. Grade 5 Stable after being left for 1 month Grade 4 Slightly thickened after leaving for 1 month Grade 3 Gelation within 1 week Grade 2 gelation within 1 day Grade 1 Gelation within 12 hours

[0030]

[Table 2]

[0031]

As described above, according to the present invention, when coating the surface of the olefinic thermoplastic elastomer molded article, the surface of the molded article is adhered without physical activation by corona discharge treatment or the like in advance. Provided is a primer composition which has a high heat resistance and can be coated with a film having heat creep resistance, solvent resistance and antiglare property. Further, by encapsulating the curing agent for the epoxy resin added to the primer composition into microcapsules, a primer composition having storage stability can be provided.

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Claims (4)

[Claims] 1. A primer composition comprising a chlorinated polyolefin having a chlorine content of 10 to 50% by weight, an epoxy resin and a curing agent. 2. The primer composition according to claim 1, wherein the curing agent is microencapsulated. 3. The primer composition according to claim 1, which is used for coating an olefinic thermoplastic elastomer molded article. 4. A method for coating a molded article, which comprises applying the primer composition of claim 1 to the surface of an olefinic thermoplastic elastomer molded article, drying the same, and then forming a top coat layer thereon.