KR20110107166A - A coating composition with an improved adhesion for nylon substrate - Google Patents

Abstract

The present invention relates to a coating composition for a nylon material with excellent adhesion, and more particularly, it is excellent in adhesion, and directly in a 2C1B (2Coat1Baking) process without prior coating or pretreatment (plasma or flame) process of a primer for adhesion. Colored coatings that are particularly suitable for nylon (6/66) or nylon composite materials (NYLON6 + PPE, NYLON66 + PPE, NYLON66 + PP, etc.) used in automobile wheel covers, because the physical properties and appearance can be secured just by coating only the top coat. It relates to a composition.

Description

A coating composition with an improved adhesion for nylon substrate

The present invention relates to a coating composition for a nylon material with excellent adhesion, and more particularly, it is excellent in adhesion, and directly in a 2C1B (2Coat1Baking) process without prior coating or pretreatment (plasma or flame) process of a primer for adhesion. Colored coatings that are particularly suitable for nylon (6/66) or nylon composite materials (NYLON6 + PPE, NYLON66 + PPE, NYLON66 + PP, etc.) used in automobile wheel covers, because the physical properties and appearance can be secured just by coating only the top coat. It relates to a composition.

Nylon material is a chain-like polymer linked by amide bonds, and various kinds of nylons such as nylon 4, 6, 7, or 66 vary depending on the bond. Nylon material is generally used as a material for automobile wheel cover because of its excellent durability and chemical resistance. For the beautiful appearance of the car, the coating is mainly made of silver colored solvent-based color coat.

However, nylon has a low surface tension, high moisture content between internal hydrogen bonds and moisture absorption in the air, which leads to severe deformation of the material, and poor dimensional stability in injection molding, such as other resins such as polypropylene (PP) or polyphenylene ether. Nylon composite material etc. which mix and shape | mold with (PPE) are developed. Since the nylon itself or the nylon composite material is poorly adhered to the paint during coating, it was necessary to apply a solvent-type primer coating or pretreatment (plasma or flame treatment) to the nylon surface before coating the colored top coat. Therefore, when painting the nylon material has been required to paint more than two times, there have been a number of problems, such as increased VOC generation, increased energy consumption, increased labor costs, increased production equipment and operating costs, and reduced efficiency of the process.

Because of these problems, the industry has been continuously required to remove the undercoat process when coating nylon material, for this purpose, the development of a topcoat composition for nylon material with excellent adhesion performance is urgently needed.

The present invention is to solve the problems of the prior art as described above, by providing an improved adhesion to nylon and nylon composite material to provide a solvent-based top coating composition that can ultimately eliminate the undercoat process It is a task.

According to an aspect of the present invention, adipic acid (Adipic acid) is prepared using a monomer, the hydroxyl value (OHV) is a hydroxyl group-containing unsaturated polyester resin having a number average molecular weight of 2000 to 2250; Full methoxy type melamine resin; And a curing accelerator; provides a coating composition comprising a.

According to another aspect of the present invention, a hydroxyl group-containing unsaturated polyester resin prepared by using adipic acid as a monomer, having a hydroxyl value (OHV) of 100 to 140, number average molecular weight of 1800 to 2000; Thermosetting acrylic resins having a glass transition temperature of 30 ° C. to 40 ° C .; Full methoxy type melamine resin; And it provides a coating composition comprising a curing accelerator.

The present invention is basically prepared using adipic acid as a monomer, and includes a hydroxyl group-containing unsaturated polyester resin and a full methoxy type melamine resin having a hydroxyl value (OHV) of 100 to 140 and a number average molecular weight of 1800 to 2250. The coating composition which consists of a main part and a hardening | curing agent part containing a hardening accelerator. At this time, when the number average molecular weight of the hydroxy group-containing unsaturated polyester resin is 2000 to 2250, a thermosetting acrylic resin may be further included in the main part as necessary. On the other hand, in the case where the number average molecular weight of the hydroxy group-containing unsaturated polyester resin is 1800 to 2000, further inclusion of a thermosetting acrylic resin having a glass transition temperature of 30 ° C. to 40 ° C. in the main body yields excellent adhesion to the nylon material. It is preferable in that it can.

Hereinafter, two aspects of the present invention as described above will be described in detail.

 (1) First aspect: of hydroxyl group-containing unsaturated polyester resin Number average  When the molecular weight is 2000 to 2250

The hydroxyl group-containing unsaturated polyester resin produced using adipic acid as a monomer used in the first aspect of the present invention has a hydroxyl value of 100 to 140 mgKOH / g and a number average molecular weight of 2000 to 2250. If the number average molecular weight is out of the above range, the adhesion to the nylon material is significantly lowered except in the case of the second side described separately below. More preferably, the number average molecular weight is 2000 to 2200.

Such hydroxy group-containing unsaturated polyester resin can be produced by reacting adipic acid as polybasic acid with polyhydric alcohols such as neopentyl glycol, diethylene glycol, trimethylol propane, and the like.

In the first aspect of the present invention, it is preferable to use a hydroxy group-containing unsaturated polyester resin having a number average molecular weight of 2000 to 2250 in an amount of 10 to 40% by weight in 100% by weight of the total coating composition. If it is less than% by weight, the flexibility, impact resistance, and adhesion of the coating film may be lowered. If it exceeds 40% by weight, solvent resistance, hardness, and storage property of the coating film may be lowered.

The number average molecular weight of the full methoxy melamine resin used in the first aspect of the present invention is preferably 300 to 1000. Full methoxy type melamine resin is obtained by superposition | polymerization of methanol and formaldehyde.

In the first aspect of the present invention, it is preferable to use the melamine resin in an amount of 5 to 20% by weight in 100% by weight of the total coating composition. If the content is less than 5% by weight, the flexibility, impact resistance, and adhesion of the coating film If it exceeds 20% by weight, solvent resistance, hardness, and shelf life may decrease.

The coating composition according to the first aspect of the present invention may further include a thermosetting acrylic resin. In the case of the thermosetting acrylic resin usable in the first aspect of the present invention, the acid value is preferably 5 to 20 mgKOH / g, and the hydroxyl value is 50 to 150 mgKOH / g. If the acid value of the acrylic resin is less than 5, there may be a problem in curing and adhesion strength. If the acid value is more than 20, the addition reaction may occur when reacting with the melamine or the isocyanate resin in the CLEAR portion. May occur. If the hydroxyl value is less than 50, the crosslinking density may be lowered, and the chemical resistance may be lowered. If the hydroxyl value is more than 150, the crosslinking density may be increased, thereby affecting the tendency of sulfur change and cracking and chipping of the coating.

In addition, the weight average molecular weight of the thermosetting acrylic resin usable in the first aspect of the present invention is preferably 7,000 to 20000, more preferably 10000 to 20000, even more preferably 10000 to 15000. If the weight average molecular weight is less than 7,000, the coating film tends to recede, and if it exceeds 20000, the adhesive force may deteriorate. Further, the glass transition temperature is preferably -10 to 60 ° C, more preferably -10 to 40 ° C, and most preferably 10 to 35 ° C. If the glass transition temperature is less than -10 ° C, the coating film tends to recede, and if it exceeds 60 ° C, the coating film is too hard to be broken.

Acrylic resins as described above may be prepared by polymerizing, for example, methyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate and (meth) acrylic acid alone or together with styrene as monomers. As the polymerization initiator, peroxides such as di-butyl peroxide can be used, and as solvents, aliphatic or aromatic hydrocarbon solvents, such as hydrocarbon solvents such as heptane, toluene and xylene, ethyl acetate, n-butyl acetate and isobutyl Esters such as acetate and methyl cellosolve acetate, ketones such as methyl ethyl ketone and methyl amyl ketone, alcohols such as ethanol, isopropyl alcohol, n-butanol and isobutane alcohol, n-butyl ether and ethylene glycol monoethyl Ethers, such as ether, can be used individually or in combination.

When the thermosetting acrylic resin is used in the first aspect of the present invention, the amount of the thermosetting acrylic resin is preferably used in an amount of 10 to 40% by weight in 100% by weight of the total coating composition in terms of adhesion and durability. In addition, the weight ratio with the hydroxy group-containing unsaturated polyester resin may be appropriately selected according to the type of nylon material and the transparent top coat (CLEAR) to which the coating composition is coated, preferably a hydroxy group-containing unsaturated polyester resin: thermosetting The weight ratio of the acrylic resin is 1: 0.1 to 1.5, more preferably 1: 0.2 to 1, it is advantageous in terms of storage properties, workability, adhesion-related properties (adhesion, water resistance, weather resistance, etc.). .

The curing accelerator used in the first aspect of the present invention promotes the curing of the hydroxyl group-containing unsaturated polyester resin and melamine to improve the density of the coating film at low curing temperature conditions to improve adhesion. In the first aspect of the present invention, it is preferable to use a curing accelerator in an amount of 1 to 25% by weight in 100% by weight of the total coating composition. If this content is less than 1% by weight, the flexibility, impact resistance, and adhesion of the coating If it exceeds 25% by weight, solvent resistance, hardness, and shelf life may be a problem. The curing accelerator preferably contains sulfonic acid at 10-50% by weight of the total weight of the curing accelerator. As the sulfonic acid, para toluene sulfonic acid, dodecylbenzene disulfonic acid, dinonyl naphthalene disulfonic acid, dinonyl naphthalene sulfonic acid and the like can be used, and para toluene sulfonic acid is most preferred.

On the other hand, when using a curing accelerator, it may be used for the skinning agent to improve storage properties and workability. In general, the main material and the curing accelerator are diluted with the diluent and then coated. However, depending on the working environment and conditions, a considerable time may elapse after the dilution, and a film is formed on the contact portion between the paint and the air. To prevent such film formation, a skinning agent is used. As an anti-skinning agent, methyl ethyl ketoxim is preferable, The usage-amount is 10-50 weight% of the total weight of a hardening accelerator, and 5-20 weight% is more preferable.

In addition to the above components, the coating composition according to the first aspect of the present invention may further include various components as described below for imparting or improving specific physical properties.

The coating composition of the present invention may include an aluminum pigment for imparting metallic color. Suitable aluminum pigments include untreated aluminum pigments, phosphated aluminum pigments, silica treated aluminum pigments, and the like. As for the usage-amount, about 3 to 8 weight% of a main part total amount is suitable, Preferably it is 4 to 7 weight%, More preferably, it is about 5 to 6 weight%. When the amount of the aluminum pigment is too small, there may be a decrease in hiding power and a decrease in metallic color, and when too much, a decrease in adhesion may occur.

In addition, the coating composition of the present invention may include cellulose acetate butyrate (CAB). In the present invention, since the different types of resins are used, compatibility between them is important, and the drying speed of the paint should proceed quickly because of the relatively low temperature curing (60-80 ° C.) type due to the characteristics of the automobile parts, and color, that is, metallic color It is desirable to increase the storage stability of the aluminum pigment paste used for imparting and to prevent sedimentation. It is CAB that can be used for this purpose. CAB grades that can be preferably used in the present invention include 531-1 SEC of EASTMAN. When CAB is used in the form of a solution, the CAB solution in which 10-30 wt% of 531-1 SEC is dissolved in solvents such as toluene, butyl acetate, ethyl acetate, and DPMA is included in the range of 5-25 wt% of the total amount of the main portion.

In addition, the coating composition of the present invention may include a wax. In general, aluminum pigment is included for the metallic color of the automotive component paints, and the specific gravity of the aluminum pigment is 2 or more, so that precipitation and agglomeration during storage are likely to occur. In addition, the orientation of the aluminum pigment is not well achieved during painting, the phenomenon that the surface is stained easily occurs. At this time, if the aluminum pigment and wax are sufficiently mixed, this phenomenon can be prevented. Examples of the waxes usable in the present invention include polyamides, polyethylenes, and ethylene vinyl acetates. The wax may be used on the order of 1 to 8% by weight of the total amount of the main part, preferably 2 to 6% by weight, more preferably about 4 to 5% by weight. When the amount of wax used is too small, the effect of improving the precipitation and aggregation of the pigment may be insignificant, and when the amount of the wax is used too much, the water resistance of the coating film and the shelf life of the paint may be deteriorated.

Moreover, it is preferable that the coating composition of this invention contains a microgel resin. Microgel resin has a good balance of thermal flowability, crosslinking reaction rate, resin viscosity, etc., and has good appearance, heat resistance, weather resistance and workability. Especially, H / SOLID is possible compared to the existing L / SOLID type. Excellent pigment orientation can be given in the ON-WET method, and in particular, it is a type that can be significantly complemented in weather resistance, so it is possible to be used in automobiles / top coats, maintenance mid / top coats, and industrial products, and can be widely expanded to construction. In addition, in solvent-based paints, staining may occur due to the flow of aluminum pigment due to the type of solvent in the paint or the fluidity between the solvent and the resin. Resin can be used to prevent this. Suitable microgel resins include those as described in Korean Patent Application No. 10-2000-0085315 to KCC. The microgel resin may be used in an amount of about 1 to 10% by weight of the total amount of the main part, preferably 2 to 8% by weight, more preferably about 4 to 6% by weight. When the amount of the microgel resin is too small, precipitation of the pigment during storage and flow of the pigment during coating may occur, and when too much, the gelation and compatibility of the paint may be impaired, and the workability may be poor and the water resistance may be deteriorated.

In addition, the coating composition of the present invention may include a fluidity regulator. The fluidity regulator is used to improve the flow of paint, the sedimentation resistance of pigments and the orientation of metallic pigments, and can be used in combination with fumed silica and ORGANOPHILIC CLAY. As the fumed silica, fumed silica powder having a specific surface area of 100 to 200 m 2 / g may be dissolved and mixed at 5 to 20% by weight of the total weight of the fluidity regulator. This helps to promote the anti-sagging properties of the resin. Examples of the fumed silica having such characteristics include aerosol 200 (Degus Co., Ltd.), V / 15 (Baker Co.) CAB-O-SIL TS-610 (CABOT Co., Ltd.) and the like, and the loss of ignition is 0.1 to 3 Phosphorus ORGANOPHILIC CLAY can be dissolved together at a level of 0.1 to 2% by weight of the total weight of the fluidity modifier to obtain an increase in the effectiveness of use. Examples of the ORGANOPHILIC CLAY having the above characteristics include BENTONE (trade names BENTONE27, BENTONE38 (ELEMENTIS SPECIALTIES)) and LAPONITE (LAPONITE RD (ROCK WOOD)). The fluidity modifier may also include an acrylic resin having the characteristics described above at a level of 0.5-40% by weight of the total weight of the fluidity modifier.

In addition, the coating composition of the present invention may contain a surface modifier. Surface modifiers are used to improve the wettability of the coating and the smoothness and slipperiness of the coating. For example, a borchers Baysilon OL17 additive can be used, which is used at 0.05 to 0.3% by weight of the total amount of the subject matter. In the case of surface conditioners, similar products are listed for each company. Therefore, a product having better compatibility with each paint may be used in an appropriate amount.

 (2) Second aspect: of hydroxyl group-containing unsaturated polyester resin Number average  When the molecular weight is 1800 to 2000

A second aspect of the present invention is a hydroxyl group-containing unsaturated polyester resin produced by using adipic acid as a monomer, having a hydroxyl value of 100 ~ 140 mgKOH / g, number average molecular weight of 1800 to 2000; A thermosetting acrylic resin having a glass transition temperature of 30 ° C. to 40 ° C .; Full methoxy type melamine resin; And a curing accelerator; relates to a coating composition comprising a.

The hydroxy group-containing unsaturated polyester resin produced using adipic acid as a monomer, which is used in the second aspect of the present invention, has a number average molecular weight of 1800 to 2000. If the number average molecular weight is out of the above range, the adhesion to the nylon material is significantly lowered except in the case of the first side described separately above. More preferably, the number average molecular weight is 1850 to 2000, and the hydroxyl value is 130 to 140 mgKOH / g.

Such hydroxy group-containing unsaturated polyester resin can be prepared from the reaction of adipic acid and polyhydric alcohol, as described above in the first aspect.

In the second aspect of the present invention, adipic acid is used as a monomer, and the hydroxyl group value is 100 to 140 mgKOH / g, and the hydroxyl group-containing unsaturated polyester resin having a number average molecular weight of 1800 to 2000 is 100% by weight of the total coating composition. It is preferable to use in an amount of 10 to 40% by weight, if the content is less than 10% by weight, the flexibility, impact resistance, and adhesion of the coating film may be lowered, and if it exceeds 40% by weight, the solvent resistance of the coating film, Hardness and shelf life may decrease.

The thermosetting acrylic resin used in the second aspect of the present invention has a glass transition temperature of 30 ℃ to 40 ℃. In the second aspect of the present invention, if the glass transition temperature of the thermosetting acrylic resin is less than 30 ° C., the coating film tends to recede, and if it exceeds 40 ° C., the coating film is too hard to be broken. The weight average molecular weight becomes like this. Preferably it is 7,000-20000, More preferably, it is 10000-20000, More preferably, it is 10000-15000. If the weight average molecular weight is less than 7,000, the coating film tends to recede, and if it exceeds 20000, the adhesive force may deteriorate. Moreover, Preferably, the acid value is 5-20 mgKOH / g, and a hydroxyl value is 50-150 mgKOH / g. If the acid value of the acrylic resin is less than 5, there may be a problem in curing and adhesion strength. If the acid value is more than 20, the addition reaction may occur when reacting with the melamine or the isocyanate resin in the CLEAR portion. May occur. If the hydroxyl value is less than 50, the crosslinking density may be lowered, and the chemical resistance may be lowered. If the hydroxyl value is more than 150, the crosslinking density may be increased, thereby affecting the tendency of sulfur change and cracking and chipping of the coating.

 Production of the acrylic resin as described above is as described in the first aspect.

In the second aspect of the present invention, it is preferable to use a thermosetting acrylic resin having a glass transition temperature of 30 ° C to 40 ° C in an amount of 10 to 40% by weight in 100% by weight of the total coating composition in terms of adhesion and durability. In addition, the weight ratio with the hydroxyl group-containing unsaturated polyester resin may be appropriately selected according to the type of nylon material and the transparent top coat (CLEAR) to which the coating composition is coated, preferably the hydroxyl group-containing unsaturated polyester resin: thermosetting The weight ratio of the acrylic resin is 1: 0.1 to 1.5, more preferably 1: 0.2 to 1, it is advantageous in terms of storage properties, workability, adhesion-related properties (adhesion, water resistance, weather resistance, etc.). .

The number average molecular weight of the full methoxy melamine resin used in the second aspect of the present invention is preferably 300 to 1000. The methoxy type melamine resin can be obtained by polymerization of methanol and formaldehyde. When the butoxy melamine resin or the methoxy / butoxy mixed melamine resin is used in the second aspect of the present invention, compatibility with the polyester resin is lowered, and the melamine is transferred to the upper layer of the paint, thereby lowering the glossiness of the coating film. And problems with adhesion in thin films.

In the second aspect of the present invention, it is preferable to use the melamine resin in an amount of 5 to 20% by weight in 100% by weight of the total coating composition. If this content is less than 5% by weight, the flexibility, impact resistance, and adhesion of the coating film If it exceeds 20% by weight, solvent resistance, hardness, and shelf life may decrease.

The curing accelerator used in the second aspect of the present invention is as described in the first aspect. In addition, the coating composition according to the second aspect of the present invention has a variety of various components that may be further included for imparting or improving specific physical properties, as also described in the first aspect.

According to the present invention, it is possible to obtain a solvent-based top coating composition that can exhibit excellent adhesion and durability to the nylon and nylon-containing composite material and ultimately eliminate the undercoat process.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by Examples.

< Example  And Comparative example  Preparation of Compositions>

The coating compositions of Examples and Comparative Examples were prepared according to the compositions shown in Tables 1 and 2, respectively (unit: parts by weight).

TABLE 1

TABLE 2

<Evaluation of Physical Properties of Prepared Coating Composition>

The paint compositions prepared in Examples and Comparative Examples were applied to the top of an automobile wheel cover (material: nylon 6 + PPE, nylon 66) to evaluate physical properties. Preparation of the test coating spray coating the coating composition prepared in each of the above Examples and Comparative Examples to the automotive wheel cover with a dry coating average thickness of 25㎛, after setting about 2-3 minutes, UT5015 (SC) as a clear paint thereon -CLEAR (manufactured by KCC, acrylic urethane solvent clear paint) was coated at a dry coating average thickness of 30 µm, and heated to dry at 70 ° C for 30 minutes to prepare a test coating. The physical properties of the following items were evaluated for the prepared coating specimens, and the results are shown in Tables 3 and 4 below.

<Property test items and methods>

(1) Appearance: The projections and gloss of the coating film surface were visually evaluated.

○: good

X: Check the abnormality of protrusion or mottling or gloss even at one point)

(2) Shelf life: 250 g of the composition was left at room temperature and 60 ° C. for 1 week in a 300 ml glass bottle, and then the viscosity change and the precipitation of silver powder were observed, and the appearance change after coating was visually determined.

O: no increase or decrease in viscosity. No pigment precipitation.

(Triangle | delta): A viscosity rises slightly. Precipitation of the pigment, but agitating soon after stirring.

X: The viscosity rises and the pigment precipitates severely.

(3) Initial adhesiveness: A cut line is drawn with a cutter to reach the surface of the coating film, 100 pieces of 2mm × 2mm squares are made, the adhesive cellophane tape is adhered to the surface, and it is rapidly peeled off at 20 ℃. The number of remaining coating films of the square was evaluated.

(4) Impact resistance: The weight of 1kg was dropped into the coating film at a height of 50cm with a DuPont impactor to measure the state of the coating film.

○: Good coating state

X: The coating film is broken or peeled off. Creative is exposed

(5) Water Resistance Adhesion: A portion of the coated bumper was cut out, immersed in warm water at 40 ° C. for 10 days, taken out and dried, and then subjected to an adhesion test, and the coated surface was visually evaluated.

○: Good adhesion. No blister occurrence

×: adhesion failure or blister generation

(6) Weatherability: The surface of the coating film was washed with a neutral detergent after 1200 hours of exposure in a SUNSHINE WETHEROMETER specified in JIS D 0205. Then, the state of drawing, color difference, and glossiness retention were examined, and the adhesion test was done according to the method of said (3).

O: no color change and no peeling off

△: There is no peeling off the scale, but there is slight cracking and color change at the cut part

X: color change or peeling off of scale

[Table 3]

[Table 4]

Claims (9)

A hydroxyl group-containing unsaturated polyester resin prepared using adipic acid as a monomer, having a hydroxyl value (OHV) of 100 to 140, and a number average molecular weight of 2000 to 2250; Full methoxy type melamine resin; And a curing accelerator; coating composition comprising a. The coating composition according to claim 1, further comprising a thermosetting acrylic resin. The acid value of the thermosetting acrylic resin is 5 ~ 20 mgKOH / g, hydroxyl value is 50 ~ 150 mgKOH / g, the weight average molecular weight is 7,000 ~ 20000, and the glass transition temperature is -10 ~ 60 ℃ Coating composition. The coating composition according to claim 1, wherein the curing accelerator contains sulfonic acid. A hydroxyl group-containing unsaturated polyester resin prepared by using adipic acid as a monomer, having a hydroxyl value (OHV) of 100 to 140, and a number average molecular weight of 1800 to 2000; Thermosetting acrylic resins having a glass transition temperature of 30 ° C. to 40 ° C .; Full methoxy type melamine resin; And a curing accelerator. The coating composition according to claim 5, wherein the acid value of the thermosetting acrylic resin is 5-20 mgKOH / g, the hydroxyl value is 50-150 mgKOH / g, and the weight average molecular weight is 7,000-20000. The coating composition according to claim 5, wherein the curing accelerator contains sulfonic acid. A nylon-based material coated with the coating composition of any one of claims 1 to 7. The nylon-based material according to claim 8, which is a wheel cover for an automobile.