KR20010058985A - Acrylic resin composition for thermocuring - Google Patents

Abstract

PURPOSE: A thermosetting cross-linkable acrylic resin composition useable as a transparent base paint is provided to obtain improved chipping-resistance and durability of the base paint at coating it in wet-on-wet manner by containing desired cross-linkable monomer component. CONSTITUTION: The acrylic resin composition comprises 100 weight parts of copolymerized monomer component containing 5-30 wt.% of cross-linkable monomer defined by formula (wherein R1 is hydrogen or methyl group; R2 is hydrogen or aliphatic alkyl group having C1-C10; R3 is hydrogen or aliphatic alkyl group having less than 4 carbon atoms), 10-45 wt.% of acrylic ester monomer, 5-20 wt.% of aromatic vinyl monomer, 5-25 wt.% of unsaturated monomer having hydroxyl radicals and 1-4 wt.% of unsaturated monomer having acid radicals; 0.5-5 weight parts of polymerization initiator and 0.01-1 weight parts of oxidation stabilizer.

Description

Thermosetting acrylic resin composition {Acrylic resin composition for thermocuring}

The present invention relates to a thermosetting acrylic resin composition modified with a self-crosslinkable acrylic monomer having excellent chipping resistance, particularly low temperature chipping resistance, adhesion, impact resistance, solvent resistance, storage stability, and good weatherability.

Recently, automotive body paints are required to improve the appearance, chemical resistance, scratch resistance, etc. due to the demand of excellent quality, mainly to develop a lot of transparent paints to satisfy this.

In addition, conventionally, the physical properties such as chipping resistance and durability are used as a primer primer paint and thermosetting paints of polyester and melamine resin. However, there is a lack of chipping resistance, durability, etc. only with the intermediate paint.

Accordingly, an object of the present invention is to provide a resin that is suitable for improving the required properties such as chipping resistance, durability, and the like of a transparent coating and a base coating containing a pigment in a wet-on-wetting method.

In addition, an object of the present invention is to provide a thermosetting acrylic resin composition which contains a crosslinkable monomer component and is excellent in chipping resistance and durability and can be used as a base paint.

The thermosetting acrylic resin composition of the present invention for achieving the above object is 5 to 30% by weight of the crosslinkable monomer represented by the following formula (1), 10 to 45% by weight acrylic acid ester monomer, 5 to 20% by weight aromatic vinyl monomer, It is characterized by consisting of 100 parts by weight of the copolymerization monomer component consisting of 5 to 25% by weight of the unsaturated monomer having a hydroxyl group and 1 to 4% by weight of the unsaturated monomer having an acid group, 0.5 to 5 parts by weight of the polymerization initiator and 0.01 to 1 part by weight of the oxidation stabilizer. do.

Formula 1

Wherein R ₁ is a hydrogen atom or a methyl group, R ₂ is a hydrogen atom or an aliphatic alkyl group having 1 to 10 carbon atoms, and R ₃ is a hydrogen atom or an aliphatic alkyl group having 4 or less carbon atoms.

The crosslinkable monomer component used in the present invention is an acrylamide in which an amino group is methyl or alkoxymethyl with a copolymerizable double bond, as shown in Chemical Formula 1.

However, in general, when the crosslinkable monomer is copolymerized with an acrylic monomer having a double bond, the resin color is yellowed, and when used in a paint, yellowing is likely to occur and weatherability may be a problem. It is characterized by its good resin color and its ability to improve weathering and yellowing problems when applied to paints.

Looking at the components of the present invention in more detail as follows.

(1) Crosslinkable monomer represented by Formula (1)

Among the components constituting the present invention, the copolymerizable crosslinkable monomers are methylated or alkoxymethylated acrylamides, including N-methylmethacrylamide, methoxymethylmethacrylamide, N-ethoxymethylmethacrylamide, and N-propol group. 1 type selected from the group consisting of methyl methacryl amide, N-isopropoxymethyl methacryl amide, N-butoxymethyl methacryl amide, N-isobutoxymethyl methacryl amide and N-tert-butoxymethyl methacryl amide It is more than that.

Such a crosslinkable monomer is contained in 5 to 30% by weight of the total copolymerization monomer components, if the content is less than 5% by weight is less self-crosslinking effect, if more than 30% by weight stability is concerned.

(2) acrylic acid ester monomer

As the acrylic ester monomer, methyl methacrylate, ethyl methacrylate, propyl methacrylate, normal butyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, 2-ethylhexyl methacrylate, benzyl methacrylate It contains 10 to 40% by weight of the total copolymerized monomer components of at least one selected from the group consisting of latex, phenyl methacrylate, stearic methacrylate, cyclohexyl methacrylate and lauryl methacrylate.

(3) aromatic vinyl monomers

As the aromatic vinyl monomer, at least one selected from the group consisting of styrene, transmethyl styrene, metamethyl styrene, alphamethyl styrene, betamethyl styrene, and 4-methyl styrene is used in 5 to 20% by weight of the total copolymerized monomer components. .

(4) an unsaturated monomer having a hydroxyl group

The unsaturated monomer having a hydroxyl group is one selected from the group consisting of beta-hydroxy ethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, and hydroxyethyl methacrylate added with ε-caprolactone. The above is used so that 5-25 weight% of all the copolymerization monomer components may be used.

(5) an unsaturated monomer having an acid group

As the unsaturated monomer having an acid group, at least one selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid is used in 1 to 4% by weight of the total copolymerized monomer components. If it is less than%, the self-crosslinkability is insufficient, and if it is more than 4% by weight, the stability is lowered and the compatibility of the solvent is also adversely affected.

As for the molecular weight of the acrylic resin obtained by such a composition, the number average molecular weight is suitable between 5,000-30,000, Preferably it is between 10,000-20,000. If the number average molecular weight is less than 5,000, it lowers the durability and solvent resistance of the coating film, and it mixes well with the transparent paint when wet-on-wet coating, which adversely affects the appearance.If the number average molecular weight exceeds 30,000, the solid content of the paint is lowered and the coating film is Reduces appearance.

As the polymerization initiator, an initiator of an azo compound is used, but azobis isobutyronitrile, azobis 2-methylbutyronitrile, azobis 2,4-dimethylvaleronitrile, azobis 4-methoxy 2, An initiator of a low temperature azo compound such as 4-dimethyl valeronitrile and dimethyl 2,2'-azobis isobutylate is used in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the copolymerized monomer.

If a high temperature polymerization initiator such as 2-cyano-2-propyl azoformamide is used, gelation may occur during polymerization (130 ° C. or higher), and yellowing of the resin color may be promoted when a polymerization initiator of peroxide is used. Let's do it.

As a method of synthesizing the acrylic resin with such a composition, a solution polymerization method is used. The organic solvent used here is toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, methanol, ethanol. , Isopropyl alcohol, normal butanol, isobutanol and the like can be used alone or in combination, and the polymerization is carried out at a temperature of 60 ~ 120 ℃.

On the other hand, in order to improve the color of the acrylic resin of the present invention, 0.1 to 1% by weight of a phosphite compound is added to the reaction as an oxidative stabilizer. However, when phosphoric acid or phosphorous acid is added to improve the appearance of the resin, there is a risk of gelation during the reaction, and in the case of phosphoric acid, attention may be required because the appearance of the resin may be turbid.

Among the oxidizing stabilizers that can be used, phosphite compounds include trisnonyl phenyl phosphite, triisodecyl phosphite, phenyl diisodecyl phosphite, diphenyl isodecyl phosphite, diphenyl isooctyl phosphite, triphenyl phosphite , Tetraphenyl dipropylene glycol phosphite, polydipropylene glycol phenyl phosphite, trisisotridecyl phosphite, trilauryl phosphite, triisooctyl phosphite, diphenyl hydrogen phosphite, bisoctadecyl hydrogen phosphite , Dioleyl hydrogen phosphite, bisisotridecyl hydrogen phosphite, diisooctyl hydrogen phosphite, lauryl bisphenol A polyphosphite, (neodol 25) bisphenol A phosphite and the like can be used.

Such a crosslinkable resin composition of the present invention can be applied to base paints, top coats, repair paints, etc., especially when applied as a base paint when painting the car body is excellent in chipping resistance, impact resistance, cold crack resistance, etc. It also has good weather resistance and can be used as a base coating for 2-coat-1 baking coating of wet on wet.

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

<Resin manufacturing>

Example 1

750 parts by weight of xylene and 250 parts by weight of normal butanol are placed in a four-necked flask equipped with a stirrer, a cooler, a thermometer and a nitrogen gas injector, and 150 parts by weight of normal butoxymethyl acrylamide while maintaining the temperature at 80 ° C. while injecting nitrogen gas. 170 parts by weight of styrene, 300 parts by weight of butyl acrylate, 180 parts by weight of hydroxyethyl methacrylate, 175 parts by weight of methyl methacrylate, and 24 parts by weight of methacrylic acid were mixed, and 20 parts by weight of azobis 2-methylbutyronitrile. 0.2 parts by weight of triisooctyl phosphite was mixed and added dropwise evenly over 3 hours, maintained for 4 hours, and the reaction was terminated.

The resin solution thus prepared became a transparent resin having a solid content of 49.7 wt%, a viscosity Z-Z1 (Gardner viscosity), an acid value of 9, and a Gardner color 1 or less.

Example 2)

750 parts by weight of xylene and 250 parts by weight of normal butanol were added to a four-necked flask equipped with a stirrer, a cooler, a thermometer, and a nitrogen gas injector, and 150 parts by weight of isobutoxymethyl acrylamide while maintaining the temperature at 80 ° C while injecting nitrogen gas. 170 parts by weight, butyl acrylate 300 parts by weight, hydroxyethyl methacrylate 180 parts by weight, methyl methacrylate 175 parts by weight, methacrylic acid 24 parts by weight are mixed, 20 parts by weight of azobis 2-methylbutyronitrile and tri 0.2 parts by weight of octadecyl phosphite was mixed and added dropwise evenly over 3 hours, maintained for 4 hours, and the reaction was terminated.

The resin solution thus prepared became a transparent resin having a solid content of 49.8 wt%, a viscosity Z1 (Gardner viscosity), an acid value of 9.1, and a Gardner color of 1 or less.

Example 3

750 parts by weight of xylene and 250 parts by weight of normal butanol are added to a four-necked flask equipped with a stirrer, a cooler, a thermometer and a nitrogen gas injector, and 150 parts by weight of N-methoxymethyl acrylamide while maintaining the temperature at 80 ° C while injecting nitrogen gas. , 170 parts by weight of styrene, 300 parts by weight of butyl acrylate, 180 parts by weight of hydroxyethyl methacrylate, 175 parts by weight of methyl methacrylate, 24 parts by weight of methacrylic acid, 20 parts by weight of azobis 2-methylbutyronitrile And 0.2 parts by weight of triisooctyl phosphite were mixed and added dropwise evenly over 3 hours, maintained for 4 hours, and the reaction was terminated.

The resin solution thus prepared became a transparent resin having a solid content of 49.6% by weight, a viscosity Z1-Z2 (Gardner viscosity), an acid value of 9.3, and a Gardner color 1 or less.

Comparative Example 1)

750 parts by weight of xylene and 250 parts by weight of normal butanol were added to a four-necked flask equipped with a stirrer, a cooler, a thermometer, and a nitrogen gas injector, and 150 parts by weight of isobutoxymethyl acrylamide while maintaining the temperature at 80 ° C while injecting nitrogen gas. 170 parts by weight, butyl acrylate 300 parts by weight, hydroxyethyl methacrylate 180 parts by weight, methyl methacrylate 175 parts by weight, methacrylic acid 24 parts by weight are mixed and 20 parts by weight of azobis 2-methylbutyronitrile The reaction was terminated evenly over 3 hours and maintained for 4 hours.

The resin solution thus prepared became a transparent resin having a solid content of 49.8% by weight, a viscosity Z1-Z2 (Gardner viscosity), an acid value of 9.1, and a Gardner color 1 or less.

Comparative example 2)

750 parts by weight of xylene and 250 parts by weight of normal butanol were added to a four-necked flask equipped with a stirrer, a cooler, a thermometer, and a nitrogen gas injector, and 150 parts by weight of isobutoxymethyl acrylamide while maintaining the temperature at 80 ° C while injecting nitrogen gas. 170 parts by weight, butyl acrylate 300 parts by weight, hydroxyethyl methacrylate 180 parts by weight, methyl methacrylate 175 parts by weight, methacrylic acid 24 parts by weight, 20 parts by weight of azobis 2-methylbutyronitrile and phosphoric acid 0.2 parts by weight of the mixture was added dropwise evenly over 3 hours, maintained for 4 hours and the reaction was terminated.

The resin solution thus prepared became a transparent resin having a solid content of 49.7% by weight, a viscosity Z1-Z2 (Gardner viscosity), an acid value of 9.3, and a color of 1 or less.

Comparative Example 3)

750 parts by weight of xylene and 250 parts by weight of normal butanol were added to a four-necked flask equipped with a stirrer, a cooler, a thermometer, and a nitrogen gas injector, and 150 parts by weight of isobutoxymethyl acrylamide while maintaining the temperature at 80 ° C while injecting nitrogen gas. 170 parts by weight, butyl acrylate 300 parts by weight, hydroxyethyl methacrylate 180 parts by weight, methyl methacrylate 175 parts by weight, methacrylic acid 24 parts by weight, 20 parts by weight of azobis 2-methylbutyronitrile and phosphorous acid 0.2 parts by weight of the mixture was added dropwise evenly over 3 hours, and then gelled in the holding.

Comparative Example 4)

750 parts by weight of xylene and 250 parts by weight of normal butanol were added to a four-necked flask equipped with a stirrer, a cooler, a thermometer, and a nitrogen gas injector, and 170 parts by weight of styrene and 375 weights of butyl acrylate while maintaining the temperature at 80 ° C while injecting nitrogen gas. Part, 180 parts by weight of hydroxyethyl methacrylate, 250 parts by weight of methyl methacrylate, 24 parts by weight of methacrylic acid were mixed, and 20 parts by weight of azobis 2-methylbutyronitrile were mixed and added dropwise to the mixture over 3 hours, and then 4 hours. The reaction was terminated after holding for.

The resin solution thus prepared became a transparent resin having a solid content of 49.9% by weight, viscosity X-Y (Gardner viscosity), an acid value of 9.2 and color 1 or less.

In order to test the coating performance of the resins prepared in Examples and Comparative Examples, paints were prepared as described below and subjected to physical property tests.

<Paint production>

1) mill base manufacturer

50% by weight of carbon black (Degussa FW-200), 200% by weight of the resin of Example 1, 5 parts by weight of butoxy melamine resin (Korea Chemical Products) 100% by weight of xylene, 100% by weight of butyl acetate for 10 hours Was produced by a ball mill to obtain a mill base (hereinafter referred to as practice M / B-1).

In this same manner, the mill bases were prepared using the resins prepared according to Examples 2 to 3 and Comparative Examples 1, 2 and 4, respectively, and then, respectively, M / B-2, M / B-3, and M / B. B-1, Comparative M / B-2 and Comparative M / B-4.

2. Base paint manufacturing

500% by weight of the resin of Example 1, 100% by weight of butoxymelamine, 30% by weight of M / B-1, rheology control agent 50% by weight, leveler 1.2% by weight, UV absorber 1.5% by weight, acid catalyst 2% by weight , 185% by weight of xylene, 60% by weight of butyl acetate, 20% by weight of normal butanol, and 70% by weight of methyl isobutyl ketone were prepared to prepare a base paint (hereinafter referred to as Example N-1).

A base paint was prepared in the same manner, but the resins of Examples 2, 3, Comparative Examples 1, 2, and 4, respectively, and M / B-2, M / B-3, and M / B were used as mill bases. -1, Comparative M / B-2 and Comparative M / B-4 were used.

Here, the rheology control agent was used as a solution in which 30% by weight of CAB 551-0.01SEC (Eastman Inc.) was dissolved in 70% by weight of butyl acetate solvent, and LC 900 (manufactured by Kusumoto) was used as a leveling agent. As a water absorbent, Tinuvin 384 (manufactured by Ciba-Geigy Co., Ltd.) and an acid catalyst were used as a solution in which 10% by weight of p-toluene sulfonic acid was dissolved in 90% by weight of xylene.

The coating material test was performed on the base paint thus obtained.The base paint was adjusted to 16 seconds at 25 ° C. on a pore cup viscometer on a specimen coated with electrodeposited and medium weight, and sprayed at 20 to 25 μm to wet with wet on wet. The paint (Korea Chemical Products) was coated and cured at 140 ° C. for 30 minutes, and then tested for physical properties. The results are shown in Table 1 below.

The property test method is as follows.

1) Paint storage: Test the viscosity change by storing paint at 60 ℃ × 3 days

2) Appearance: Sun Young Sung-Inspected using a tension meter

Gloss: 60 ° inspection with BYK micro-tri-gloss

3) Impact resistance: No peeling, no crack at 500g / 20cm × 1 / 2''φ

4) Chipping resistance: after maintaining -40 ℃ φ3 hours

5) Solvent resistance (Xylene resistance): Spot method

6) Gasoline resistance: Comparison of coating state after 1 hour deposition

7) Adhesion: No peeling, no crack at cross cut 100/100 (2mm)

8) Weather resistance: Comparison of coating state after 2000 hours using QUV machine manufactured by Q-Panel

Example Comparative example B-1 B-2 B-3 B-1 B-2 B-4 Paint Storage Good Good Good Good Good Good Sunyoung Sung 17 17 17 16-17 16 17 Glossy (60 °) 94 94 94 92 91 93 Impact resistance 50 50 50 50 50 40 Cold Cracking 32 times 30 times Episode 31 24 times 30 times 25 times Chipping resistance 7 7 7 7 7 6+ Solvent resistance 8 9 8 9 10 13 Petty Good Good Good Good Good Good Weather resistance (2000 hours) Good Good Good chalk Good Good Adhesion 100/100 100/100 100/100 100/100 100/100 100/100

From the results of Table 1, it can be seen that when the resin of the present invention is applied to an automobile base coat, it has excellent chipping resistance, impact resistance, cold crack resistance, etc., and also has good paint storage resistance and weather resistance.

As described in detail above, the acrylic resin copolymerized with a crosslinkable acrylic monomer and other vinyl crab monomers and acrylic monomers according to the present invention crosslinks upon heating, and in particular, it can be cured even at low temperatures and is stable at room temperature. As it forms excellent mechanical properties, it is applied to automobile paints to improve low temperature chipping resistance, impact resistance and cold cracking resistance, and in general, when curing the automobile paints, a curing temperature of 150 ° C or more is usually required and a separate curing agent is used. On the other hand, when the resin composition of the present invention is applied, self-crosslinking is possible at low temperature (130 ° C.) alone, or may be mixed with other curing agents. In general, during the coating process of automobile body coating paint, the base coating and the transparent coating which give color to the vehicle body through the electrodeposition coating and the middle coating process are coated by wet on wet 2 coat 1 baking method. The invention is a crosslinkable acrylic resin composition that can be used as a base paint.

Claims (9)

5-30 wt% of the crosslinkable monomer represented by the following formula (1), 10-45 wt% of the acrylic ester monomer, 5-20 wt% of the aromatic vinyl monomer, 5-25 wt% of the unsaturated monomer having a hydroxyl group and an unsaturated having an acid group A thermosetting acrylic resin composition comprising 100 parts by weight of a copolymerized monomer component consisting of 1 to 4 parts by weight of monomer, 0.5 to 5 parts by weight of a polymerization initiator, and 0.01 to 1 parts by weight of an oxidation stabilizer. Formula 1 Wherein R ₁ is a hydrogen atom or a methyl group, R ₂ is a hydrogen atom or an aliphatic alkyl group having 1 to 10 carbon atoms, and R ₃ is a hydrogen atom or an aliphatic alkyl group having 4 or less carbon atoms. According to claim 1, wherein the crosslinkable monomer represented by the formula (1) is characterized in that N-methyl methacrylate amide, methoxymethyl methacryl amide, N-ethoxymethyl methacryl amide, N-propoxymethyl methacryl At least one member selected from the group consisting of amide, N-isopropoxymethylmethacryl amide, N-butoxymethylmethacryl amide, N-isobutoxymethylmethacryl amide and N-tertiarybutoxymethylmethacryl amide Thermosetting acrylic resin composition to be. The method of claim 1, wherein the acrylic ester monomer is methyl methacrylate, ethyl methacrylate, propyl methacrylate, normal butyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, 2-ethylhexyl methacrylate A thermosetting acrylic resin composition, characterized in that at least one selected from the group consisting of acrylate, benzyl methacrylate, phenyl methacrylate, stearic methacrylate, cyclohexyl methacrylate and lauryl methacrylate. The thermosetting acrylic resin composition according to claim 1, wherein the aromatic vinyl monomer is at least one selected from the group consisting of styrene, transmethyl styrene, metamethyl styrene, alphamethyl styrene, betamethyl styrene, and 4-methyl styrene. 2. The unsaturated monomer having a hydroxyl group according to claim 1 is composed of beta-hydroxy ethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate and hydroxyethyl methacrylate added with ε-caprolactone. Thermosetting acrylic resin composition, characterized in that at least one member selected from the group. The thermosetting acrylic resin composition according to claim 1, wherein the unsaturated monomer having an acid group is at least one member selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid. The polymerization initiator of claim 1, wherein the polymerization initiator is azobis isobutyronitrile, azobis 2-methylbutyronitrile, azobis 2,4-dimethylvaleronitrile, azobis 4-methoxy 2,4-dimethyl valeronitrile. And dimethyl 2,2'-azobis isobutylate. Thermosetting acrylic resin composition, characterized in that. The oxidizing stabilizer according to claim 1, wherein the oxidizing stabilizer is trisnonyl phenyl phosphite, triisodecyl phosphite, phenyl diisodecyl phosphite, diphenyl isodecyl phosphite, diphenyl isooctyl phosphite, triphenyl phosphite, tetraphenyl Dipropylene glycol phosphite, polydipropylene glycol phenyl phosphite, trisisotridecyl phosphite, trilauryl phosphite, triisooctyl phosphite, diphenyl hydrogen phosphite, bisoctadecyl hydrogen phosphite, dioleyl At least one member selected from the group consisting of hydrogen phosphite, bisisotridecyl hydrogen phosphite, diisooctyl hydrogen phosphite, lauryl bisphenol A polyphosphite and (neodol 25) bisphenol A phosphite Thermosetting acrylic resin composition. A base coating for 2-coat-1 baking coating of wet-on-wet for automobiles, comprising the thermosetting acrylic resin composition of claim 1.