JPH03109471A - Primer composition and use thereof - Google Patents

Abstract

PURPOSE:To obtain a primer composition increasing adherability of paint to molded article surface of polyolefin, etc., by dissolving modified polymer of styrene-isoprene block copolymer (hydrogenated material) in organic solvent in a specific ratio. CONSTITUTION:The aimed composition is composed of (A) modified polymer obtained by graft polymerization of (ii) 0.05-25wt.% alpha,beta-unsaturated vinyl monomer [preferably (meth)acrylic ester of (polyhydric) alcohol] having hydroxyl group to (i) styrene. isoprene block copolymer (hydrogenated material) dissolved in (B) organic solvent such as toluene in a ratio of 5-80wt.% the component A and 95-20wt.% the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a primer composition, in particular,
Molded products made of polyolefin such as polypropylene, molded products such as automobile bumpers made of polypropylene and synthetic rubber, SMC molded products made of unsaturated polyester resin, epoxy resin, etc., R-R made of polyurethane resin, etc.
This invention relates to a primer composition for undercoating IM molded products, glass fiber-reinforced polyamide resin molded products, cationic electrodeposition coated steel plates, etc. to improve the adhesion of paint to the surfaces of these molded products.

A coating film is formed on the surface of a molded article made of polyolefin such as polypropylene to increase its added value. However, molded products made of polyolefin generally have low polarity and poor adhesion with paint, so conventionally, the surface of the molded product is treated with a primer composition in advance to prevent the paint film from adhering to the surface of the polyolefin molded product. Efforts are being made to improve the properties or adhesion.

For example, styrene, butadiene,
(meth)acrylic acid ester and hydroxyalkyl (meth) in the presence of hydrogenated styrene block copolymer
JP-A-63-51477 describes the use of a so-called polymer alloy obtained by polymerizing acrylate as a binder resin for a one-coat paint to form a paint film without primer treatment. .

However, when the above binder resin is used as a primer, the peel strength of the coating film is not sufficient.

The present inventors determined the amount of hydroxyl group α in the styrene-isoprene block copolymer or its hydrogenated product.

A primer composition prepared by dissolving a modified polymer obtained by graft copolymerizing a β-unsaturated vinyl monomer in an organic solvent has excellent adhesion to polyolefins such as polypropylene and molded products of other resins. The inventors have discovered that the film has excellent water resistance, bending resistance, image clarity, etc., and have arrived at the present invention.

The primer composition according to the present invention for styrene/isoprene block copolymer or its hydrogenated product contains 0.05 to 25% by weight of an α,β-unsaturated vinyl monomer having a hydroxyl group.
A composition obtained by dissolving a modified polymer obtained by graft copolymerization so as to contain the modified polymer 5 in an organic solvent.
~80% by weight and 95~20% by weight of the above organic solvent.

The styrene/isoprene block copolymer used in the present invention is represented by the general formula % (wherein, S represents a styrene polymer block, D represents an isoprene polymer block, and n represents O or 1). . The production of such styrene-isoprene block copolymers is described, for example, in U.S. Pat. No. 3,265.
It is described in the specification of No. 765, and also in JP-A-61-
It is also described in No. 192743. As a commercial product, styrene/isoprene block copolymers are available as CARIFLEX (manufactured by Shell Chemical Co., Ltd., hereinafter the same) TR1107 and TR1117.

In addition, the production of hydrogenated products of styrene/isoprene block copolymers is disclosed in, for example, Japanese Patent Publication No. 42-8704,
Special Publication No. 43-6636, Special Publication No. 45-20504
No. 48-3555, Japanese Patent Publication No. 48-3555, etc.

The primer composition according to the present invention includes such a styrene-isoprene block copolymer or a hydrogenated product thereof (hereinafter, these may be simply referred to as a block copolymer).

) and an α,β-unsaturated vinyl monomer (hereinafter simply referred to as vinyl monomer) having a predetermined amount of hydroxyl groups is dissolved in an organic solvent. It is a composition.

Here, the block copolymer or its hydrogenated product used in the present invention is selected from the viewpoint of the strength and solid content concentration of the coating film of the resulting primer composition, in a tetrahydrofuran solvent.
It is preferable that the number average molecular weight measured by gel permeation chromatography at 0°C is 1XIO' to 18X10', particularly 1.5XIO' to 12X
The styrene content is preferably 10', and the styrene content is
From the viewpoint of adhesion and strength, low-temperature properties, stickiness, etc. of the coating film of the resulting primer composition, the content is preferably 10 to 60% by weight, and particularly preferably 12 to 55% by weight.

The modified polymer used in the present invention for the helmet has a content of 0.0
The above-mentioned vinyl monomers are graft copolymerized onto the block copolymer so that the block copolymer has vinyl monomers having hydroxyl groups in an amount of 5 to 25% by weight. By using such a modified polymer, it is possible to obtain a primer composition that forms a coating film with excellent adhesion and water resistance. A particularly preferred amount of the vinyl monomer in the modified polymer is 0.5 to 20
% by weight.

In the present invention, as the α,β-unsaturated vinyl monomer having a hydroxyl group, a (meth)acrylic ester of a monohydric alcohol or a mono(meth)acrylic ester of a polyhydric alcohol is preferably used. Therefore, as vinyl monomers, for example, hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,
-Hydroxy-3-phenoxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)
acrylate, glycerin mono(meth)acrylate,
Examples include pentaerythritol mono(meth)acrylate, trimethylolpropane mono(meth)acrylate, tetramethylolethane mono(meth)acrylate, butanediol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, and the like.

Also, 10-undecen-1-ol, 1-octene-
3-ol, 2-methanol norbornene, hydroxystyrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-methylol acrylamide, 2-(meth)acryloyloxyethyl acid phosphate, glycerin monoallyl ether, allyl alcohol, allyloxyethanol, 4- (Hydroxypolypentylcarboxyloxy)ethyl (meth)acrylate and the like can also be used.

The graft copolymer of the vinyl monomer to the block copolymer is prepared by polymerizing the vinyl monomer to the block copolymer in the presence of a radical polymerization initiator in an inert solvent such as toluene. You can get it by doing this.

An example of a preferred method is: inert solvent IC
A solution is prepared by dissolving 10 to 3,000 kg, preferably 20 to 1,000 kg of the block copolymer, and 0 to 0 of the vinyl monomer is added to this solution per 1 kg of the block copolymer.
．． The radical polymerization initiator is added sequentially at a rate of 5 to 100 mmol/min, preferably 1 to 20 mmol/min, and at the same time, the radical polymerization initiator is also added at a rate of about 5X10-' to 1 kg of block copolymer.
50 mmol/min, preferably 10-2 to 5 mmol/min
Add sequentially at a rate of 100 min. The amount of the radical polymerization initiator added is approximately 1/100 to 31 times the amount of the vinyl monomer.
5, preferably a molar ratio range of about 1/20 to 1/2.

The graft copolymerization of the vinyl monomer onto the block copolymer is preferably carried out in an inert solvent under heating and strong stirring. The reaction temperature is preferably 50°C or higher, particularly preferably in the range of 80 to 200°C, and the reaction time is suitably 2 to 10 hours. The reaction method may be either batchwise or continuous, but
In order to carry out the graft copolymerization uniformly, a batch method is preferable.

However, graft copolymerization of a vinyl monomer onto a block copolymer can be carried out in the presence of a vinyl monomer and a radical polymerization initiator even in the absence of a solvent, as long as the reaction temperature is above the softening point of the block copolymer. This can also be carried out by heating and melting the block copolymer and stirring vigorously. Furthermore, the styrene-butadiene block copolymer, the vinyl monomer, and the radical polymerization initiator can be mixed in advance and then graft copolymerized using an extruder.

As the radical polymerization initiator used in the graft copolymerization of the vinyl monomer to the block copolymer, organic peroxides or organic bere esters are preferably used. Specifically, for example, benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-
t-Butyl peroxide, 2,5-dimethyl-2,5-
Di(peroxybenzoate)hexyne-3,1,4-
bis(t-butylperoxyisopropyl)benzene,
lauroyl peroxide, t-butyl peracetate,
2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3,2,5-dimethyl-2°5-di(t
-butylperoxy)-hexane, t-butyl perbenzoate, t-butyl perphenylacetate, t-butyl perisobutyrate, t-butylperu S-octoate, t-butyl pervivalate, cumyl perpivalate, t- Butyl perdiethyl acetate and the like are preferably used. In addition to these, azo compounds such as azobisisobutyronitrile, dimethylazoisobutyrate, etc. can also be used.

The primer composition according to the present invention is obtained by dissolving the graft copolymerization of a vinyl monomer onto the block copolymer obtained as described above in an organic solvent. Therefore,
Depending on the case, the solution obtained by performing the graft copolymerization in the inert solvent may be used as it is or diluted with an organic solvent as appropriate to form the primer composition of the present invention, or the modified polymer may be prepared as a primer composition according to the present invention. It may be isolated once and then dissolved in an organic solvent. In addition, as mentioned above, the block copolymer is heated and melted in a reaction vessel without a solvent,
Alternatively, after performing graft copolymerization using an extruder, the obtained graft copolymer may be dissolved in an organic solvent.

The organic solvent in the primer composition of the present invention includes:
Any solvent is not particularly limited as long as it can dissolve the graft copolymer described above (usually aromatic hydrocarbon solvents such as toluene and xylene, aliphatic solvents such as hexane, heptane, octane, and decane). Hydrocarbon solvents, alicyclic hydrocarbon solvents such as cyclohexane, cyclohexene, methylcyclohexane, chlorinated hydrocarbon solvents such as trichlorethylene, perchlorethylene, dichloroethylene, dichloroethane, chlorobenzene, aliphatic solvents such as ethanol and isopropanol Examples include alcohol solvents, ketone solvents such as acetone, methyl isobutyl ketone, and methyl ethyl ketone, and ester solvents such as ethyl acetate.

The primer composition according to the present invention includes 5 to 80% by weight of the graft-modified copolymer and 95 to 20% by weight of the organic solvent.
, preferably 7 to 60% by weight of the graft-modified copolymer
and 93 to 40% by weight of the organic solvent.

The primer composition according to the present invention may optionally contain chlorinated polypropylene, chlorinated maleated polypropylene, hydroxyl group-containing chlorinated polypropylene, etc., or styrene-butadiene-styrene block copolymer or its hydrogenated product, Styrene/ethylene/propylene block copolymers, modified copolymers in which chlorine atoms, hydroxyl groups, carboxyl groups, carboxylic acid anhydride groups, etc. are introduced into these copolymers, modified copolymers in which multiple of these modifications are carried out, etc. May be added.

Furthermore, the primer composition according to the present invention contains a halogen atom, a hydroxyl group, A copolymer into which one or more carboxyl groups, carboxylic acid anhydride groups, etc. are introduced may be added as necessary.

Further, the primer composition according to the present invention can be mixed with an isocyanate compound and used as a paint.

Furthermore, the primer composition according to the present invention has, in addition to the above,
If necessary, it may contain ingredients such as various stabilizers such as antioxidants, weather-resistant stabilizers, and heat-resistant inhibitors, coloring agents such as titanium oxide and organic pigments, and conductivity imparting agents such as carbon black and ferrite. Good too.

The primer composition according to the present invention is suitably applied to the surface of a molded article made of polyolefin or other polymer to improve the adhesion of paint to the surface. In particular, the primer composition according to the invention may include, for example:
High-pressure polyethylene, medium-low pressure polyethylene, polypropylene, poly-4-methyl-1-pentene, poly-1-
It can be suitably used for molded articles made of polyolefins such as butene and polystyrene, and polyolefin copolymers such as ethylene/propylene copolymers, ethylene/butene copolymers, and propylene/butene copolymers.

Furthermore, in addition to the above-mentioned polyolefins and their copolymers, the primer composition according to the present invention can also be made from molded products made of polypropylene and synthetic rubber, polyamide resins, unsaturated polyester resins, polybutylene terephthalate resins, polycarbonate resins, etc. It can be used for molded products such as automobile bumpers, and also for surface treatment of steel plates, electrodeposited steel plates, and the like. In addition, polyurethane resin, fatty acid modified polyester resin, oil-free polyester resin,
Primer coats surfaces coated with paints, primers, adhesives, etc. whose main ingredients are melamine resin, epoxy resin, etc., and improves the adhesion of paints, etc. to the surface, as well as improves image clarity and low-temperature impact resistance. It is also used to form excellent coatings.

In particular, the primer composition according to the present invention can be applied to SMC molded products of unsaturated polyester resin, R-R molded products of polyurethane resin, etc.
It is suitably used for IM molded products, glass fiber reinforced polyamide resin molded products, polyurethane resin molded products, cationic electrodeposition coated steel sheets, etc.

The primer composition according to the present invention is particularly useful when the molded product to which it is applied contains inorganic fillers such as talc, zinc white, glass fiber (titanium white, magnesium sulfate, etc.), pigments, etc. Forms a primer coating with good properties.

The molded product may also contain various stabilizers, ultraviolet absorbers, hydrochloric acid absorbers, etc. in addition to the above. Preferably used stabilizers include, for example, 2,6-di-t-butyl-4-methylphenol, tetrakis[methylene(
3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane, metaoctadecyl-3-(4'-hydroxy-3,5-di-t-butylphenyl)propionate, 2゜2゛-methylenebis( 4-methyl-6-t
-butylphenol), 4,4'-butylidene bis(
3-methyl-6-t-butylphenol), 4.4'
-thiobis(3-methyl-6-t-butylphenol)
, 2,2-thiobis(4-methyl-6-t-butylphenol), 1.3,5-trimethyl-2,4,6-tris(3,5-t-7"thyl-4-hydroxybenzyl) Benzene, phenolic stabilizers such as 1.3.5-f-lis(2-methyl-4-hydroxy-5-t-butylphenol)butane, sulfur such as dilaurylthiodipropionate, distearylthiodipropionate, etc. Examples include phosphorus stabilizers such as tridecyl phosphite and trinonylphenyl phosphite.

Preferably used ultraviolet absorbers include, for example, 2
-Hydroxy-4-octoxybenzophenone, 2-ethylhexyl-2-cyano-3,3-diphenylacrylate, para-octylphenyl salicylate, and the like. As the hydrochloric acid absorbent, for example, calcium stearate or the like is preferably used.

The primer composition according to the present invention is suitable for spray coating on a molded article, for example, by spraying onto the surface of the molded article with a spray gun. The molded article may be coated at room temperature, and after being coated, it is dried by an appropriate method, such as natural drying or forced drying under heat, to form a coating film.

After the primer composition according to the present invention is applied to the surface of a molded product and dried, a paint is applied to the molded product by a method such as electrostatic painting, spraying, or brushing. . These paints may be applied by applying a primer coat and then a top coat.

There are no particular restrictions on the paint used, but if a coating film with high paint adhesion is required, solvent-based thermoplastic acrylic resin paint, solvent-based thermosetting acrylic resin paint, acrylic modified alkyd resin, epoxy Resin paints, polyurethane resin paints, melamine resin paints, etc. are preferably used.

After applying such a paint, the paint film is cured by a conventional method such as nichrome wire, infrared rays, or high frequency heating to obtain a molded product. The method of curing the coating film is appropriately selected depending on the material and shape of the molded article, the properties of the coating material, etc.

The primer composition according to the present invention is a modified polymer obtained by graft copolymerizing a styrene-isoprene block copolymer or a hydrogenated product thereof with an α,β-unsaturated vinyl monomer having a hydroxyl group. This composition is dissolved in a solvent and has a high solid content concentration, making it easy to work with. Furthermore, it can be atomized, so it forms a coating film with excellent paint adhesion as well as excellent image clarity. do.

In particular, the coating film of a molded article coated with the primer composition according to the present invention has excellent smoothness and the durable adhesion of the coating film is improved. Such effects are also exhibited when the primer composition is spray coated.

The present invention will be explained below with reference to examples and examples.
The present invention is not limited in any way by these Examples. In addition, below, the physical property test of the coating film was conducted as follows.

A test piece with a base grain is prepared according to the base grain test method described in JIS K 5400, and after pasting cellophane tape on the base grain, it is immediately rotated at a 90° angle.
The substrate was peeled by pulling in the direction, and evaluation was made based on the number of substrate stitches that were not peeled out of 100 substrate stitches.

Peel Strength Prepare a coating film on a substrate, make a cut with a cutter blade of 1c'11 width until the blade reaches the substrate, peel the edge, and then peel the edge of the peeled coating film. 1 at a rate of 50moi/min
The peel strength was determined by pulling in the 80° direction.

The water resistance test piece was immersed in water at 40° C. for 240 hours, and then a base grain test was conducted.

Bending resistance A test piece was prepared by applying the primer composition to a bendable base material with a thickness of 2 cm, and this was placed along a cylinder with a diameter of 10III11 at a temperature of -30°C with the coated side facing outward. It was bent and its condition was visually observed. The evaluation criteria are as follows.

◎ No cracks occurred in either the paint film or the primer.

No cracks occurred in the O paint film, but no cracks occurred in the primer.

Δ Cracks occur in the paint film and primer.

X Cracks also occurred in the base material.

Sharpness was evaluated using a sharpness gloss meter PGD-4 manufactured by Tokyo Koden ■.

Reference Example 1 This Reference Example shows an example of producing a styrene/isoprene/styrene block copolymer and its hydrogenated product.

However, the method for producing the styrene-isoprene-styrene block copolymer and its hydrogenated product is not limited to this reference example.

In a reactor, 90 g of styrene was dissolved in 1400 g of benzene and heated to 40°C, and then 0.003 mol of sec-butyllithium was added to polymerize all the styrene at 40°C.

Next, 420 g of isoprene was newly added to the reactor, and all of the isoprene was further polymerized at 40°C. Further, 90 g of styrene was newly added, and all of the styrene was polymerized at 40°C.

The styrene content of the styrene/isoprene/styrene block copolymer thus obtained was 30% by weight.

The above styrene/isoprene/styrene block copolymer was dissolved in cyclohexane to form a 10% by weight solution.

To this solution, 0.5 g of nickel catalyst on diatomaceous earth was added per 1 g of copolymer, and the mixture was heated at 145 to 155°C for 13 hours.
Hydrogenation was carried out under a hydrogen pressure of 35 kg/c4.

The iodine value of the hydrogenated styrene/isoprene/styrene block copolymer thus obtained was 3.6 g.
I! /100 g copolymer. The iodine value of the copolymer before hydrogenation is 272 g I t / 10
It was 0g copolymer.

Example 1 A hydrogenated product of the styrene-isoprene block copolymer obtained in Reference Example 1 (number average molecular weight 4.6 %) and 500 parts by weight of toluene were charged, and the temperature was raised to 160°C while stirring. Then,
After 25 parts by weight of 2-hydroxypropyl acrylate and 6.8 parts by weight of di-t-butyl peroxide were each added in portions over 4 hours, the mixture was further stirred at 160°C for 2 hours.

In the modified polymer thus obtained, the 2-hydroxypropyl acrylate content was 5.92% by weight,
The Ford Cup viscosity of the modified polymer solution diluted with toluene to a solid content of 133 times, ie, the primer composition, was 19.4 seconds at a temperature of 25°C.

After cleaning the base materials shown in Table 1 by the method shown in Table 1,
After applying the above primer composition to a dry film thickness of 11 μm using a spray gun, top coat R
-271 (white) (manufactured by Nippon B Chemical) with a dry film thickness of 60
It was coated to a thickness of μm. After cooling at room temperature for 10 minutes, baking was performed in an oven at 100°C for 30 minutes. Table 1 shows the physical properties of the resulting coating film.

Comparative Example 1 The same procedure as in Example 1 was carried out, except that the same hydrogenated styrene-isoprene block copolymer as in Example 1 was used as it was, and the solid content was reduced to 13.0 with toluene.
% by weight. Ford cup viscosity is at a temperature of 25°
In C, it was 25.0 seconds.

After cleaning the base materials shown in Table 1 by the method shown in Table 1,
It was applied in the same manner as in Example 1, and top coat R-271 (
White) (manufactured by Nippon Bee Chemical) was applied. After cooling,
Baking was performed for 30 minutes in an open state at 100°C. Table 1 shows the physical properties of the resulting coating film.

Example 2 Table 1 shows the physical properties of a coating film obtained in the same manner as in Example 1, except that the primer composition obtained in Example 1 was applied to the substrate shown in Table 1.

Example 3 A modified copolymer was obtained in the same manner as in Example 1, except that 2-hydroxyethyl acrylate was used as the vinyl monomer. This modified copolymer was diluted with toluene and cyclohexane to a solid content of 12% by weight. The solvent composition after dilution was a toluene/cyclohexane weight ratio of 8/2, and the Ford cup viscosity was 20 seconds at a temperature of 25°C.

As shown in Table 1, R-R using urethane resin
Table 1 shows the physical properties of the coating film obtained in the same manner as in Example 1 except that it was applied to the surface of the IM molded product.

Examples 4 to 6 Table 1 shows the physical properties of coating films obtained in the same manner as in Example 1, except that the primer composition obtained in the same manner as in Example 1 was applied to the substrate shown in Table 1. .

Claims (1)

[Scope of Claims] (1) A styrene/isoprene block copolymer or a hydrogenated product thereof is graft copolymerized to contain 0.05 to 25% by weight of an α,β-unsaturated vinyl monomer having a hydroxyl group. 1. A primer composition comprising 5 to 80% by weight of the modified polymer and 95 to 20% by weight of the organic solvent. (2) α,β-unsaturated vinyl monomer having hydroxyl group is 1
2. The primer composition according to claim 1, wherein the primer composition is a (meth)acrylic ester of a hydrolic alcohol or a mono(meth)acrylic ester of a polyhydric alcohol. (3) A primer for polyolefin mainly comprising the primer composition according to claim 2. (4) A primer for unsaturated polyester resin-based SMC molded products, which is mainly composed of the primer composition according to claim 2. (5) A primer for polyurethane resin-based R-RIM molded products, which is mainly composed of the primer composition according to claim 2. (6) A primer for glass fiber-reinforced nylon mainly comprising the primer composition according to claim 2. (7) A primer for a cationically electrodeposited steel plate, the primer composition being mainly composed of the primer composition according to claim 2.