JPH01292069A - Primer composition for molded article of resin and coating - Google Patents

Abstract

PURPOSE:To obtain the title composition providing multi-layer coating films having excellent finishing properties, adhesivity, warm water resistance, weather resistance, etc., comprising a polyurethane resin modified with prepolymers containing two and three hydroxyl groups as a vehicle component. CONSTITUTION:The aimed composition comprising a polyurethane resin modified with (A) a prepolymer containing two hydroxyl groups on the average in one molecule and (B) a prepolymer containing three or more hydroxyl groups on the average in one molecule as a vehicle component. The composition is applied to molded articles of resin to form a coating film, which is then successively coated with a curable base coating compound and a curable clear coating compound to coat the molded articles of resin.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a primer composition for resin molded products, and improves finish quality by applying the primer composition to resin molded products.
This invention relates to a coating method that forms a multilayer coating with excellent adhesion, hot water resistance, weather resistance, etc.

(Prior Art and its Problems) Conventionally, a primer composition is applied to a polyurethane on automobile-related parts or car bodies.

The above primer composition uses a reaction product of a polymer diol having a primary hydroxyl group and an aromatic diincyanate compound as a vehicle component, but the film formed using this primer composition is a resin molded product or a base coat. It does not necessarily have satisfactory performance in terms of adhesion and weather resistance. For this purpose, a color base coat is usually formed between the brimer film and the base coat, but since this requires a complicated coating process, it has been desired to shorten the process.

(Means for Solving the Problems) As a result of various studies on methods to overcome the above-mentioned problems, the inventors of Rei et al. developed a prepolymer (hereinafter referred to as "prepolymer") having an average of two hydroxyl groups in one molecule. Polymer (A
)") and a prepolymer having an average of 3 or more hydroxyl groups in one molecule (hereinafter referred to as "prepolymer (
When using a ply soba composition containing a polyurethane resin modified with B) as a vehicle component, the finish, adhesion, and
It was discovered that it was possible to form a film for the entire coating system that had excellent hot water resistance and weather resistance, leading to the completion of the present invention. -0 Prepolymer (A) used in the brimer composition of the present invention
is a conventionally known prepolymer, and includes, for example, polyether diol, polyester diol, polyether, ester diol, polycarbonate diol, acrylic diol, and the like.

Examples of polyether diols include alkylene oxides of low molecular weight glycols (ethylene glycol, propylene glycol, 1,4-butanediol, etc.),
Those obtained by ring-opening polymerization or ring-opening copolymerization (block or random) of alkylene oxide (e.g., ethylene oxide, propylene oxide, butylene oxide) adducts of No. 4 and alkylene oxide cyclic ethers (tetrahydrofuran, etc.), such as polyethylene glycol, polypropylene glycol , polyethylene-propylene (block or random) glycol, dioxybutramethylene glycol, dioxyhexamethylene glycol, dioxyoctamethylene glycol and mixtures of two or more thereof.

Polyester diols include (anhydrous) dicarboxylic acids (
(e.g. adipic acid, cono-phosphoric acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, phthalic acid, etc.) and glycols (e.g. ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 118 -Octamethylene diol, neopentyl glycol, bishydroxymethylcyclohexane, bishydroxyethylbenzene, alkyl dialkanolamine, m-xylylene glycol, 1.4-bis(2-hydroxyethoxy)benzene, 4.4'-bis(2 -hydroxyethoxy)-diphenylpropane],
Those obtained by subsequent polymerization, such as polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polyethylene/propylene adipate, polyester diols consisting of bishydroxymethylcyclohexane and C4-C80 chain dicarboxylic acid mixtures (e.g. KING Industries In. Co, +
Examples of polyether ester diols include ether group-containing diols (such as polyether diols, diethylene glycol, and , triethylene glycol, dipropylene glycol, etc.) or mixtures thereof with other glycols, with the dicarboxylic acid or (anhydrous) dicarboxylic acid compounds (phthalic anhydride, maleic anhydride, etc.) and alkylene oxides. What can be done,
An example is poly(polyoxytetramethylene) adipate.

Assuming polycarbonate diol, then - soft formula % (1
) (wherein, R is a residue of a saturated aliphatic diol, and X represents the number of repeating units in the molecule, and is usually an integer of 5 to 50).

The polycarbonate diol is a saturated aliphatic diol (1,4-butanediol, 1.5-bentanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, oxypropylene glycol, etc.) in such a proportion that both ends have OH groups. ethylene oxypropylene copolymerized diol, etc.) and substituted carbonates (
transesterification method; by reacting the saturated aliphatic diol with phosgene, or, if necessary, further reacting with a saturated aliphatic diol. Polycarbonate diol is disclosed in U.S. Patent No. 3,110,
No. 686-53.

As the acrylic diol, hydroxy(meth)acrylate (e.g. hydroxy(meth)acrylate, hydroxypropyl(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, caprolactone-modified (meth)acrylate, etc.) or Examples include those in which a hydroxyl group-containing monomer such as N-methylol (meth)acrylamide and other copolymerizable monomers are copolymerized so that an average of two monomers are present in one molecule. Examples of the other copolymerizable monomers include C1-12 alkyl (meth)acrylate (such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl ( (meth)acrylate, stearyl (meth)acrylate, etc.) and aromatic monomers (eg, styrene, α-vinylstyrene, vinyltoluene, etc.).

Among these diols, polytetramethylene glycol, polycaprolactone diol, polyester diol consisting of a mixture of bishydroxymethylcyclohexane and a linear carboxylic acid of 04 to CB are particularly suitable.

□ ″Furthermore, as the prepolymer (B) used in combination with the prepolymer (A), for example, polyester polyol,
Examples include polyether ester polyols, polycarbonate polyols, acrylic polyols, and the like. Examples of the "polyester polyol" include those obtained by replacing the glycol with a polyol having a valence of 7'c or higher in the description of reacting the dicarboxylic acid (anhydride) of the polyester diol with a glycol. [
[Polyether ester polyol], ether group-containing diol (for example, polyether diol, diethylene glycol, triethylene glycol, diethylene glycol, etc.) or a mixture of these and other glycols and a trivalent or higher valent poly(anhydride) carboxylic acid [( (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, etc.). Examples of the "polycarbonate polyol" include those obtained by replacing the saturated aliphatic diol with the trivalent or higher valent polyol described below in the description of reacting the substituted carbonate or phosgene of the polycarbonate diol with a saturated aliphatic diol. Examples of the "acrylic polyol" include those obtained by combining and copolymerizing the monomers described in acrylic diol so that each molecule contains an average of three or more hydroxyl groups. Examples of the trivalent or higher polyols include trimethylolethane, trimethylolpropane, pentaerythritol, chrycerin, diglycerin, sorbitol, dipentaerythritol, and the like.

The number average molecular weight of the above prepolymers (A) and (B) is 2
It is preferably within the range of 00 to 2000, particularly 300 to 1000. If the molecular weight is less than 200, the amount of binding of the diisocyanate compound to obtain a polyurethane resin having a number average molecular weight of 95,000 to 50,000 will increase, and the resulting primer composition will have poor soluble properties in organic solvents and sprayability. On the other hand, if the molecular weight exceeds 2,000, the amount of diisocyanate added will decrease, resulting in a lack of film toughness and low-temperature flexibility and adhesion. There is.

The polyurethane resin used in the primer composition of the present invention is a reaction product obtained by adding and warping one of the above prepolymers (A) and (B) with a diisocyanate compound.

Examples of diincyanate compounds include aliphatic diisocyanates (ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate,
hexamethylene diisocyanate, lysine diincyanate, etc.), alicyclic diisocyanates (inphorone diisocyanate, hydrogenated 4,4'-Schiff-nilmethane diisocyanate, inglopylidenecyclohexyl diisocyanate, etc.), araliphatic diisocyanates (xylylene diisocyanate, nl-tetramethylxylylene diisocyanate, etc.).

Among these, especially hexamethylene diisocyanate,
Preferred are inphorone diisocyanate, m-tetramethylxylylene diisocyanate, and the like.

The blending ratio of the diisocyanate compound and prepolymers (4) and (B) is determined so that the obtained polyurethane resin has hydroxyl groups and falls within the following molecular weight range, but usually, the prepolymers (A) and ( B) total 10
The diisocyanate compound is blended in an amount of 5 to 40 parts by weight per 0 parts by weight.

The polyurethane resin thus obtained has a number average molecular weight s,
o o o~50,000, preferably 8,000~3
It can have a range of 0.000. If the number average molecular weight is smaller than s, o o o, the primer film will lack low-temperature flexibility, and if the primer film is coated with wet-on-wet base paint or topcoat, the surface of the topcoat will have wrinkles, unevenness, etc. Paint film defects occur,
On the other hand, if the number average molecular weight exceeds 50,000, the storage stability of the primer composition will be poor, coating workability (poor atomization during spray coating) will be poor, and the smoothness of the primer film formed will be reduced. This is not preferable because it causes defects such as deterioration of the finished appearance of the topcoat film.

In the production of the polyurethane resin, an organic solvent that is inactive in the reaction system can be used.

Examples of organic solvents include aromatic solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as n-butyl acetate and ethyl acetate, ethyl calpitol, diethylene glycol monoether ether acetate (carpi One or more of carpitol-based solvents such as (toll acetate), saturated hydrocarbon-based solvents such as heptane, octane, and cyclohexane, and ether-based solvents, petroleum-based solvents, and mineral spirits are used.

The primer composition of the present invention contains the above polyurethane resin as a vehicle component, and in addition to this component, if desired, for example, an organic solvent [for example, the above organic solvent and an alcoholic solvent such as methanol or n-butanol, Selonulp solvents such as ethyl cellosolve, butyl cellosolve, ethylene glycol monoethyl ether acetate (Selonulp acetate), plasticizers or plastic resins,
Paint film strengthening resin, dispersant, coating surface conditioner, fluidity conditioner,
Various known additives such as ultraviolet absorbers, ultraviolet stabilizers, and antioxidants may be added to the composition.

Also, Kibatsu F! The A2° limer composition can be made into a paint by blending pigments in order to adjust the desired color tone. Examples of pigments that can be used include inorganic pigments such as metal oxides and hydroxides, chromates, silicates, sulfides, sulfates, carbonates, various fixed pigments, carbon black, etc. Frame money R
Pigments used in regular paints, such as flakes, are used.

Furthermore, the zero-shot (7) primer composition contains polyurethane M.
, N-methyl-2-
Preferably, pyrrolidone, 2-pyrrolidone, N-vinyl-2-pyrrolidone and the like are used.

The method for preparing the primer composition of the present invention may be performed using the same equipment and steps as those used in conventional paint manufacturing methods. For example, use a suitable dispersion machine such as a ball mill, sand mill, or roll mill to create a pigment paste by dispersing the pigment in a mixture of binder and solvent, then add the necessary ingredients and mix uniformly with a disperser, etc. It can be made into a paint using a method.

The coating method of the present invention can be carried out by applying the above primer composition to the surface of a resin molded article to form a film, and then sequentially applying a curable base coat paint and a curable clear paint.

The resin #: molded product is particularly preferably a urethane resin molded into parts or products used in automobiles (e.g. bumpers, fascias, spoilers, etc.), home appliances, furniture, etc. can. In addition to the above-mentioned urethane resin molded products, it can also be used for other resin molded products, metals, wood products, paper, etc.

The primer composition can be applied by conventional painting methods. In other words, paint diluted with an organic solvent to a suitable viscosity for painting can be applied at room temperature or at elevated temperatures using an air spray machine, an airless spray machine, various electrostatic coating machines, dipping, a roll coating machine, a brush, etc. .

The film formed by the primer composition is heated or
The base coat is applied wet. The heating conditions are, for example, about 60°C to 140°C for about 1 minute to 2 minutes.
All you have to do is choose suitable conditions within the 4 hour range.

Next, the base coat paint to be applied to the Pushimer film is a pearl finish coated with titanium oxide and/or iron oxide using a curable resin as a vehicle component and containing a 7c mica flake particle pigment. Although known materials can be appropriately selected and used based on the required performance, it is preferable to use a combination of a base resin such as polyester or acrylic resin and a crosslinking agent such as melamine resin or block polyincyanate. It is.

The base coat paint can be applied in the same manner as described for the primer composition above.

Furthermore, the clear paint applied to the above base coat is
A clear paint containing the same resin as the vehicle component as described above can be used as the base coat paint.

Furthermore, the clear paint can be applied in the same manner as the climber composition.

Further, the clear paint is usually applied wet on wet after applying the base coat paint, and further heated at about 60°C to 160°C for about 1 minute to 24 hours, preferably at about 100°C to 100°C in the case of melamine-based paint. Baking is carried out at 160 DEG C. for about 10 minutes to 60 minutes, or preferably at about 70 DEG C. to 140 DEG C. for about 10 minutes to 60 minutes in the case of polyisocyanate.

(Effects of the Invention) The present invention provides excellent adhesion to the resin molded product and base coat when the specific primer composition as described above is applied particularly to a polyurethane resin molded product. This method has the remarkable effect of eliminating the need for a color base coat, saving labor in line processes, and forming a coating film with excellent durability (particularly weather resistance) of the multilayer coating of the entire coating system.

(Example) The present invention will be explained below using examples.

In addition, parts and % indicate weight parts and weight t%.

[Production example of polyurethane resin solution]

(A-1): Number average molecular weight 1250 in 4 Lof flasks
．． Polycaprolactone with an average number of hydroxyl groups per molecule of 2 (
480 parts of toluene was added to 38 parts of polycaprolactone (Plaxel 308, manufactured by Daicel) with a number average molecular weight of 850 and an average number of hydroxyl groups of 3 per molecule, and the mixture was heated to +-120°C for 1 hour. After continuous dehydration, 474 parts of methyl ethyl ketone was added, and 75 parts of hexamethylene diisocyanate was cooled and maintained at 80°C.
1 part was added dropwise over 1 hour, and the mixture was further reacted until the pheno incyanate value was 0.5 or less and the pheno viscosity was Z. 6 parts of methanol was added and the mixture was cooled to form a 40% polyurethane varnish.
fL. The number average molecular weight of this polyurethane is 29.000
Met.

(A-2): 375 parts of polycaprolactone (PCL-212 manufactured by Daicel) with an average number of hydroxyl groups of 2 per molecule (hydroxyl value 90) in a flask with a number average molecule of 81250.
Number average molecule f! 'r 1 o Polytetramethylene glycol (PTMG-1000 manufactured by Sanyo Chemical Co., Ltd.) with an average number of 2 hydroxyl groups (hydroxyl value 112) per OO11 molecule 60
parts, number average molecular weight 550. Average number of hydroxyl groups per molecule 3
Polycaprolactone (Daicel Plaxel 3)
05), 110 parts of toluene were added, and the mixture was heated to 140°C to remove a trace amount of water from the system while refluxing the toluene. 7559 parts of methyl ethyl keto was added and the mixture was cooled to 80°C. Then, inphorone diisocyanate 89
1 liter of n-butyl alcohol was added over 1 hour at a constant rate, and the reaction was continued for another 4 hours. Dilute and cool Gardner's 40% polyurethane resin phenol. The number average molecular weight of this polyurethane resin was 27,500.

[Example of manufacturing color primer]

Color primer (WA-1): Synthesized as above, then add titanium white R-70 to 250 parts of polyurethane resin solution (A-1).
6 (manufactured by Teikoku Kako Co., Ltd., titanium oxide pigment) 80 parts was added to a ball mill, dispersed for 12 hours, and N-methylpyrrolidone 5
0 part and 0.01 part of silicone oil KP-323 (manufactured by Shin-Etsu Chemical Co., Ltd.) were added to make a total of 1380.01 parts of paint.

Color primer (RA-1): Add 45 parts of quinacridone to 250 parts of the polyurethane resin solution (A-1) synthesized above.
1R (manufactured by Toyo League Co., Ltd., Akachinryo) 10 parts plus ballumi
60 parts of N-methylpyrrolidone and 1 part of silicone oil KP-3230.0 were added to make a total of 1.
The amount of paint was 320.01 parts.

・Color primer (WA-2): 250 parts of the polyurethane resin solution (A-2) synthesized above was added with titanium white (R-
706) was added, and the same procedure as below (WA-1) was made to obtain a total of 11,380.01 parts of paint.

Example 1 The above color primer (WA-1) was diluted with toluene to a viscosity of 13 seconds (Ford Cup 44720°C), prepared as follows, and then air sprayed onto a polyurethane test piece so that the dry film thickness was 20μ. Then, it was set at room temperature for 5 minutes.

Furthermore, a commercially available pearl finish paint for soft materials, Soflex A1400 White Pearl (manufactured by Kansai Paint Co., Ltd., polyester/melamine resin, titanium white coating mica coating), was sprayed to a dry film thickness of 20μ. After setting for 5 minutes, dry Soflex A 1600 Clear (manufactured by Kansai Paint Co., Ltd., acrylic/melamine resin). # Spray to a thickness of 36μ and leave at room temperature 1
After setting for 0 minutes, dry in an electric hot air dryer at 120℃.
A coated plate was prepared by baking for 30 minutes. The test results of the obtained coated plates are shown in the table.

[Preparation of painting materials]

A RIM-PU (+7 action injection molding polyurethane) molded car bumper was cut out to 5 x 20 eM, and 1.
It was exposed for a minute to degrease it and use it as a test piece.

Example 2 A coated plate was prepared in exactly the same manner as in Example 1 using the color primer (WA-2) described above.

The test results of the obtained coated plates are shown in the table.

Example 3 The color primer (RA-1) described above was applied in the same manner as in Example 1. Furthermore, a commercially available pearl finish paint for soft materials, Sofre Ix A1400 Red Pearl (manufactured by Kansai Paint Co., Ltd., polyester/melamine resin, iron oxide coated mica pigment) was sprayed to a dry film thickness of 18μ, and the mixture was heated at room temperature 5. Soflex A1600 after minute sevetaining
Spray clear so that the dry film thickness is 36μ,
After setting for 10 minutes at room temperature, dry in an electric hot air dryer for 12 minutes.
A coated plate was prepared by baking at 0°C for 30 minutes.

The test results of the obtained coated plates are shown in the table.

Comparative Example I Primer for RIM-PU, So7 Refx Flat 1000 White (manufactured by Kansai Paint Co., Ltd., MDI-based urethane distomer)
in toluene with a viscosity of 13 seconds (Ford Cup'#-4/2
0° C.), air sprayed onto the polyurethane test piece prepared above so that the dry film thickness was 20 μm, and left at room temperature for 5 minutes.

Furthermore, in the same manner as in Example 1, Raflex A140
A coated plate was prepared by painting and baking 0 white pearl and Soflex ml 600 clear. The test results of the obtained coated plates are shown in the table.

Comparative Example 2 Primer for RIM-PU, Soflexum 1000 Red (manufactured by Kansai Paint Co., Ltd., MDI-based urethane elastomer)
was coated in the same manner as in Comparative Example 1. Furthermore, in the same manner as in Example 3, a coated plate was prepared by painting and baking Soflexum 1400 Red Pearl and Nflex 41600 Clear. The test results of the obtained coated plates are shown in the table.

Comparative Example 3 RIM PU Dub Rima Flex Rin 1000
Gray (manufactured by Kansai Paint Co., Ltd., MDI urethane elastomer) with wotoluene viscosity 13 g' (Ford Cubuna 4
/20°C), air sprayed onto the polyurethane test piece prepared above so that the dry film thickness was 15A, and set at room temperature for 5 minutes.

In addition, as a color base, Soflex Flat 1200 White (
Air spray polyester/melamine resin (manufactured by Kansai Paint Co., Ltd.) to a dry thickness of 20 μm, and leave it at room temperature for 5 minutes.
After setting for 3 minutes, dry in an electric hot air dryer at 120℃ for 3 minutes.
Baked for 0 minutes.

Then, in the same manner as in Example 1, the Soflex shop 140
A coated plate was prepared by painting and baking 0 White Pearl and Soflex A 1600 Clear. The test results of the obtained coated plates are shown in the table.

Comparative example 4 RIM PUU primer, 1000 boiled in 1000
Gray was painted and set in the same manner as in Comparative Example 3.

In addition, N7 Rex A1200 red (
Kansai Paint Co., Ltd., polyester/melamine resin) was air-sprayed to a dry film thickness of 20μ, and
After setting for 3 minutes, dry in an electric hot air dryer at 120℃ for 3 minutes.
Baked for 0 minutes. Subsequently, in the same manner as in Example 3, Tufflex A1400 red crowbar and Soflex flat 1600
A coated plate was made by painting and baking clear. The test results of the obtained coated plates are shown in the table.

According to the test results in the table, Examples 1 to 3 showed the same finish and durability as Comparative Examples 3 to 4, which were painted using the 4C-3B method using a breech, and the conventional RIM-PUU primer was colored. It can be seen that in Comparative Examples 1 and 2, which were used as primers, poor adhesion and significant yellowing occurred due to weather resistance, making them unusable.

(Note-1) Visually observe the glossiness and texture of the paint film indoors under conditions of 500 lux or more of daylight color fluorescent lighting.

(Note-2) When you make 100 square stitches on the painted surface that reach the substrate at 1-pitch intervals, apply cellophane tape on top of it, press it down evenly with uniform force, and then quickly peel off the tape. Count the number of eyes left.

(Note-3) The coated plate was immersed in a hot water tester at 40° C. for 10 days and then taken out, and the surface was observed and the same goblin adhesion test as above was performed.

(Note-4) The painted plate was placed on the exposure platform on Okinoerabu Island, facing south at 22°.
After being installed at an angle of 12 months, it was washed with water and subjected to 60' gloss and color difference and goblin adhesion tests similar to those described above.

Claims (1)

[Claims] 1. A resin whose vehicle component is a polyurethane resin modified with a prepolymer having an average of 2 hydroxyl groups per molecule and a prepolymer having an average of 3 or more hydroxyl groups per molecule. Primer composition for molded products. 2. A resin molded product, characterized in that the primer composition according to claim 1 is applied to a resin molded product to form a film, and then a curable base coat paint and a curable clear paint are sequentially applied. Painting method.