JPH03287679A - Primer composition for phenolic resin - Google Patents

Abstract

PURPOSE:To obtain the title composition which can be utilized as a primer having excellent adhesiveness in the high-grade finish coating of phenolic resin moldings by mixing a principal component composed mainly of a mixture of urethane polyol and a pigment, and a curing agent component composed mainly of a polyisocyanate prepolymer. CONSTITUTION:An isocyanate-curing two-pack primer composition for phenolic resin moldings which consists of a principal component composed mainly of a mixture of urethane polyol and a pigment, and a curing agent component composed mainly of a polyisocyanate prepolymer, wherein the urethane polyol to be used has an OR value of 5 to 40 and the polyisocyanate prepolymer is incorporated in an amount of 2-60 pts.wt. (solids) based on 100 pts.wt. (solids) urethane polyol.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a primer composition for applying various coatings and decorations to phenolic resin molded articles.

More specifically, the present invention relates to a primer composition that has excellent adhesion to phenolic resin molded products, which have often been used unpainted due to adhesion problems.

PRIOR ART Conventionally, phenolic resin materials have been used for electrical products and ashtrays as automobile interior parts because of their excellent electrical properties and heat resistance.

In the field of coatings, melamine-curing paints such as melamine alkyd paints, isocyanate-curing paints such as acrylic urethane paints, and oxidation-curing alkyd paints have been used as one-coat top paints. Therefore, currently there is no need for a primer, and since it is often used without painting, its development,
No improvements have been made.

In recent years, due to the diversification of hobbies and diversification of designs, paints with various designs have been developed and applied to interior parts of automobiles.

However, these paints have weak adhesion to phenolic resin materials and cannot be used to such an extent that the development of a primer with good adhesion is awaited. Attempts have been made to use conventional one-coat top coat paints such as melamine alkyd paints as primers, but when top coat paints are applied on top of such primer coats, there is still a possibility that the phenolic resin material surface and the paint film will be in contact with each other. Painting has not been done until now because it reduces adhesion. In addition, when urethane lacquer paint is used as a primer, it has good adhesion, but flakes occur during the moisture resistance test (50°C x 98% RH, 10 days), so this is also insufficient in terms of performance. .

Problems to be solved by the invention Developed a primer with excellent adhesion that enables high-grade finishing coating of phenolic resin molded products, and developed a primer that will enable high-grade finishing of future automobile interiors. It is an object of the present invention to do so.

Means for Solving the Problem According to the present invention, the above-mentioned object is achieved by combining (A) a main component containing a pigment blended with a urethane polyol;
In the isocyanate-curing type two-component primer composition for phenolic resin molded products, which is composed of a curing agent component containing a polyisocyanate prepolymer as a main component, the OH value of the urethane polyol is 5 to 40, and the urethane polyol has a hardening agent component of 100 ( This can be achieved by an isocyanate-curable two-component primer composition for phenolic resin molded articles, which is characterized in that the polyisocyanate prepolymer is contained in a ratio of 2 to 60 parts (solid weight) to 2 parts (solid weight).

The urethane polyol used as the main component (A) of the two-component brimer composition of the present invention is a polyol containing a urethane bond in the main chain, such as polyalkylene glycol, linear polyester polyol, isophorone diisocyanate, hexamethylene Those obtained by reacting bifunctional isocyanates such as diisocyanate and tolylene diisocyanate are preferably used.

In addition, other polyols, such as those whose main chain is C-
1 such as acrylic polyol consisting of C bonds, polyester polyol containing polyester bond in the main chain, polyether polyol containing ether bond in the main chain, epoxy polyol having epoxy functional group in the main chain, nitrocellulose resin, or alkyd resin. It is also possible to use one or more types in combination within the range of 10% by weight of the urethane polyol.

The OH value of these urethane polyols is required to be in the range of 5 to 40. If the 06 value is less than 5, flakes will occur in the moisture resistance test, and if the 01 valence exceeds 40, the same flakes will occur, which is not preferable.

As the polyisocyanate prepolymer of the curing agent component (B) in the two-component brimer composition of the present invention, conventional compounds having isocyanate groups or prepolymers thereof are conveniently used.

For example, aliphatic or alicyclic diisocyanate compounds known as non-yellowing type or non-yellowing type (isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, etc.), aromatic diisocyanate I compounds known as yellowing type (diphenylmethane-4 ,4゛-
diisocyanate, etc.), triisocyanate compounds or polyisocyanates containing urea bonds, allophanate bonds, biuret bonds, isocyanurate ring structures, and isocyanate group-terminated prepolymers obtained by reacting with active hydrogen compounds (tolylene diisocyanate □ trimethylolpropane). xylylene diisocyanate, trimethylolpropane prepolymer, etc.), and these polyisocyanates may be used alone or in combination of two or more.

The solid content weight ratio of the above polyurethane polyol and polyisocyanate prepolymer is polyurethane polyol 10
0 parts to 2 to 60 parts of polyisocyanate prebolimer
must be within the range of If the amount of polyisocyanate prepolymer is less than 2 parts, blistering will occur in the moisture resistance test, and if it exceeds 60 parts, the coating will become sticky and the adhesion will be insufficient in the moisture resistance test, which is undesirable. Pigment blended with urethane polyol Almost all color pigments and extender pigments commonly used in paints can be used.

Typical examples of color pigments include titanium dioxide, Bengara, carbon black, phthalocyanine blue, quinacridone red, phthalocyanine green, and the like. Extender pigments include precipitated barium sulfate, talc, calcium carbonate, and the like. Alcohol solvents are not preferred as they react with isocyanate, but most other organic solvents can be used, and are mixed as appropriate depending on the coating environment.

In addition, various additives can be used as necessary. Examples of additives include silicone additives typified by dimethylpolysiloxane, fatty acid amides, polyalkylene glycols, and the like. Of course, as a reaction catalyst,
Reaction accelerators for two-component paints, such as dibutyltin dilaurate and cobalt naphthenate, can also be used as appropriate.

The above-mentioned coloring pigments, extender pigments, etc. that are blended into the urethane polyol are mixed into the urethane polyol together with other components, such as solvents and additives, if necessary, and are uniformly dispersed using a dispersing machine to form (A) main component paint. Prepared as a liquid.

(A) base component coating liquid prepared in this manner and (B)
Since the curing agent of the curing agent component is a two-component paint, it is mixed at the time of painting to prepare a primer paint liquid according to the present invention, which can be applied by a spray method or the like.

Effects Unlike conventional paints for phenolic resin molded products, the primer according to the present invention can be applied with various top coats, and the development of the primer of the present invention has made it possible to decorate phenolic resin molded products, which was previously impossible. This is because it has made it possible to apply new designs that are possible with paint. In other words, a major effect is that the degree of freedom in design has been greatly expanded.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In each steel, parts indicate parts by weight.

Examples 1 to 5, Comparative Examples 1 to 4 After wiping the surface of a commercially available phenol resin plate measuring 70Il111 x 701m x 3+a with an isopropyl alcohol-impregnated cloth to remove the stain, the coating viscosity (7 Auto Cup NO., 4°20°C A primer prepared with diluted thinner was applied by air atomization (13 seconds at given name:
R-263) was adjusted to a coating viscosity (Four F Cuff N0.4, 14 seconds at 20°C) using the same topcoat paint thinner, and air atomization was applied on the primer coating.
Dry by heating at 0°C for 30 minutes (dry film thickness is 40μ in total of primer and top coat).

Table 1 shows the type and composition of each component of the primer used and the type and composition of the diluting thinner components.

The obtained test pieces were subjected to a moisture resistance test and a coating film adhesion test before and after the test, and the results are also listed in Table 1.

The test method is shown below.

Humidity resistance; temperature 49±1℃, relative humidity 98%
A test piece was placed in a cabinet, left for 240 hours, and then taken out to evaluate the presence or absence of blistering.

Evaluation criteria: O if there is no blistering, × if blistering occurs
And so.

11 lines reaching the material were drawn on the coated surface of the m2 test piece with a cutter knife at 2-position intervals vertically and horizontally, cellophane tape was applied to the 100 squares created, and then carefully peeled off. Evaluation was made based on the state of peeling.

Evaluation criteria: ○ if there was no peeling, and × if the entire surface peeled.

Claims (1)

[Claims] An isocyanate-curing type two-component primer for phenolic resin molded products, consisting of (A) a main component whose main component is a mixture of urethane polyol and a pigment, and (B) a curing agent component whose main component is a polyisocyanate prepolymer. In the composition, the OH value of the urethane polyol is 5 to 40.
For use in isocyanate-curable two-component phenolic resin molded products, characterized in that the polyisocyanate prepolymer is comprised of 2 to 60 parts (solid weight) of polyisocyanate prepolymer to 100 parts (solid weight) of urethane polyol. Primer composition.