JP3395075B2 - Aqueous coating composition for fluorine resin - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous coating composition having good adhesion and compatibility with a fluororesin and can be widely used in various aqueous paints.

[0002]

2. Description of the Related Art In the field of architectural coatings, a top coat made of a resin having excellent weather resistance such as a silicone resin or a fluorine resin in order to meet the user's needs for maintaining the appearance of a building for a long time. The development of paints for automobiles is progressing.

However, paints using these resins, particularly fluorine-based resins, have poor adhesion to paints using other acrylic resins, and therefore, intermediate coatings using conventionally used acrylic resins are used. In some cases, paints and base coats could not be used.

Further, since the fluorine-based resin is inferior in compatibility with the conventionally used acrylic resin, when the fluorine-based resin and the acrylic resin are blended and used,
In some cases, problems such as a decrease in gloss may occur when each resin is used alone.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has excellent adhesion to a coating material using a fluororesin,
Further, it is an object of the present invention to provide an aqueous coating composition having improved compatibility.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that when an emulsion obtained by emulsion-copolymerizing a monomer having a specific structure is used, a fluororesin is used. It has been found that it has excellent adhesiveness to the coating material using and the compatibility is improved, and the present invention has been completed.

That is, the present invention comprises (a) 5 to 80 parts by weight of tert-butyl (meth) acrylate, (b) 0.1 to 10 parts by weight of an ethylenically unsaturated carboxylic acid monomer,
And (c) other ethylenically unsaturated monomers 10 to 9
4.9 parts by weight [(a) ~ (c) the total amount of the component 100 parts by weight is a fluorine-based resin for aqueous coating composition characterized by containing an emulsion comprising a copolymer obtained from.

In the present invention, "(meth) acrylate" means "acrylate and / or methacrylate".

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below.

The tertiary butyl (meth) acrylate, which is the component (a) for constituting the emulsion copolymer, is 5 to 80 parts by weight based on 100 parts by weight of the total amount of the components (a) to (c). It is necessary to use it in the range of 10 parts by weight, and particularly preferably in the range of 10 to 70 parts by weight. By using in this range, it becomes possible to exhibit excellent adhesion and compatibility with the fluororesin. That is, when the amount used is 5 parts by weight or more, sufficient adhesion and compatibility with the fluororesin can be obtained. Further, when the amount is 80 parts by weight or less, compatibility and adhesion to the fluororesin can be maintained without hardening the coating film.

The ethylenically unsaturated carboxylic acid monomer which is the component (b) for constituting the copolymer of the emulsion is 0.1 parts by weight based on 100 parts by weight of the total amount of the components (a) to (c). It is necessary to use within the range of 1 to 10 parts by weight, particularly preferably within the range of 2 to 10 parts by weight, and more preferably within the range of 2 to 8 parts by weight. That is, when the amount used is 0.1 part by weight or more, the dispersion stability of the emulsion is improved, and when a pigment is added to the aqueous coating composition for coloring, an agglomerate is generated during mixing. It can be avoided. Further, when the amount is 10 parts by weight or less, the dispersion stability can be maintained without increasing the viscosity of the emulsion, and the water resistance of the obtained coating film does not decrease.

Examples of the ethylenically unsaturated carboxylic acid monomer as the component (b) include (meth) acrylic acid, itaconic acid, 1,2-cyclohexanedicarboxylic acid monohydroxyethyl (meth) acrylate, and 1,2. -Monohydroxypropyl cyclohexanedicarboxylate (meth)
Acrylate, monohydroxyethyl (meth) acrylate tetrahydrophthalate, monohydroxypropyl (meth) acrylate tetrahydrophthalate, monohydroxyethyl (meth) acrylate 5-methyl-1,2-cyclohexanedicarboxylate, monohydroxyethyl phthalate (meth ) Acrylate, monohydroxypropyl (meth) acrylate phthalate, monohydroxyethyl (meth) acrylate oxalate and the like.

Further, as the ethylenically unsaturated carboxylic acid monomer, the following general formula (I) CH ₂ ═CR ¹ —COO—C ₂ H ₄ —OC (O) —R ² —COOH (I) Where R ¹ represents H or CH ₃ , and R ² has 2 to 2 carbon atoms.
28 groups are shown. It is preferable to use a monomer represented by the formula (1).

By using the ethylenically unsaturated carboxylic acid monomer having the structural formula represented by the general formula (I), excellent adhesiveness can be imparted to a metal substrate while maintaining the stability as an emulsion. it can.

Examples of the ethylenically unsaturated monomer represented by the general formula (I) include 1,2-cyclohexanedicarboxylic acid monohydroxyethyl (meth) acrylate and tetrahydrophthalic acid monohydroxyethyl (meth) acrylate. , Tetrahydrophthalic acid monohydroxypropyl (meth) acrylate, 5-methyl-1,2
Examples include cyclohexanedicarboxylic acid monohydroxyethyl (meth) acrylate, phthalic acid monohydroxyethyl (meth) acrylate, and 2-methacryloyloxyethyl hexahydrophthalate.

Examples of the other ethylenically unsaturated monomer which is the component (c) for constituting the emulsion copolymer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate and n-butyl ( It has an alkyl group having 1 to 18 carbon atoms such as (meth) acrylate, i-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate and stearyl (meth) acrylate ( (Meth) acrylic acid alkyl ester; 2
-Hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; ethylene glycol di (meth) acrylate, butylene glycol di (meth)
Glycol di (meth) acrylate such as acrylate;
Alkylamino (meth) acrylates such as dimethylaminoethyl (meth) acrylate; dimethylaminoethyl (meth) acrylate methyl chloride salts; allyl (meth) acrylate; trimethylolpropane tri (meth) acrylate; glycidyl (meth) acrylate;
Aromatic vinyl compounds such as styrene, α-methylstyrene, p-methylstyrene; vinyl acetate; vinyl propionate; (meth) acrylonitrile; benzyl (meth) acrylate; isobornyl (meth) acrylate.

The emulsion copolymer has a theoretical glass transition temperature (theoretical Tg) calculated from the Fox calculation formula, preferably from -20 ° C to 70 ° C, more preferably from -10 ° C.
It is advisable to set the mixing ratio of the components (a) to (c) so as to be 60 ° C. It is preferable that the theoretical Tg is -20 ° C or more because the coating film does not have tackiness and stains are less likely to adhere to the periphery of the coated portion before coating the fluororesin for top coating. Further, when the temperature is 70 ° C. or lower, the formed coating film does not become too hard, and cracks and the like do not occur in the thermal cycle test, which is preferable.

The Fox formula is the following relational expression for the glass transition temperature (Tg) of the copolymer.

1 / Tg = Σ (Wi / Tgi) (Wi represents the weight fraction of the monomer i, Tgi represents the Tg of the homopolymer of the monomer i.) To obtain an emulsion of the copolymer, a surfactant is used. is necessary. The amount of the surfactant used is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the total of the components (a) to (c). The presence of the surfactant in the emulsion within this range makes it possible to maintain the stability at the time of formulation of the coating material, the stability over time, etc. without significantly reducing the water resistance of the coating film.

Examples of the surface active agent include conventionally known anionic, cationic and nonionic surface active agents, and further polymeric emulsifiers. Further, a so-called reactive emulsifier having an ethylenically unsaturated bond in the surface active component can also be used.

Furthermore, the emulsion constituting the fluorine-based resin for aqueous coating compositions of the present invention, as component (c),
It is preferable to use a carbonyl group- or aldehyde group-containing vinyl monomer and to add an organic hydrazine derivative having two or more hydrazine residues to the aqueous medium of the emulsion (water which is the main dispersion medium). With such a configuration, a room temperature crosslinkable one-pack type aqueous coating composition capable of forming a coating film having improved water resistance and solvent resistance while maintaining high substrate adhesion in a wet state be able to.

This carbonyl group- or aldehyde group-containing vinyl monomer is polymerizable with at least one kind of carboxylic acid group, keto group other than ester group and amide group and aldehyde group in the molecule, and It is a monomer having a heavy bond.

The amount of the carbonyl group- or aldehyde group-containing vinyl monomer used is preferably 1 to 10 parts by weight, more preferably 1.5 to 9 parts by weight. This usage is 1
When the amount is more than the weight part, the solvent resistance and water resistance of the coating film are sufficiently improved. Further, when the amount is 10 parts by weight or less, stable emulsion polymerization becomes possible.

Examples of the carbonyl group- or aldehyde group-containing vinyl monomer include acrolein, diacetone acrylamide, formyl styrene, vinyl alkyl ketone and the like. Preferably, vinyl methyl ketone having 4 to 7 carbon atoms, vinyl ethyl ketone, vinyl isobutyl ketone, and the following general formula (II) CH ₂ ═CR ³ —COO—CHR ⁴ —CR ⁵ R ⁶ —CHO (II) ( In the formula, R ³ represents H or CH ₃ , and R ⁴ and R ⁵ are H
Alternatively, it represents an alkyl group having 1 to 3 carbon atoms, and R ⁶ represents an alkyl group having 1 to 4 carbon atoms. In addition to (meth) acryloyloxyalkylpropanal represented by), (meth) acrylamidopivalinaldehyde, diacetone (meth)
Examples thereof include acrylate, acetonitrile acrylate, 2-hydroxypropyl acrylate acetyl acetate, acetoacetoxyethyl (meth) acrylate, butanediol-1,4-acrylate-acetylacetate, and acrylamidomethylanisaldehyde. Among them, acrolein, diacetone acrylamide and vinyl methyl ketone are particularly preferable. Further, it is also possible to use two or more kinds of these carbonyl group- or aldehyde group-containing vinyl monomers in combination.

When an organic hydrazine derivative having two or more hydrazine residues is used, the ratio of the number of moles of the carbonyl group in the copolymer (A) to the number of moles of the hydrazine residue in the dispersion medium (B). Is preferably 0.1 ≦ (A) / (B) ≦ 10, and 0.8 ≦ (A) /
It is more preferable to add so that (B) ≦ 2.
When this (A) / (B) is 0.1 or more, the stability of the aqueous coating composition is improved, and stable storage for a long period of time becomes possible. Further, when it is 10 or less, the solvent resistance of the coating film is sufficiently improved.

Examples of the organic hydrazine derivative include dicarboxylic acid hydrazides having 2 to 10 carbon atoms, preferably 4 to 6 carbon atoms, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide and adipic acid. Dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, isophthalic acid dihydrazide, itaconic acid dihydrazide, and aliphatic water-soluble hydrazine having 2 to 4 carbon atoms, for example, ethylene-1,2-dihydrazine, propylene Examples include 1,3-dihydrazine and butylene-1,4-dihydrazine. Among these, adipic acid dihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide, and succinic acid dihydrazide are particularly preferable. It is also possible to use two or more of these in combination.

In order to obtain an emulsion constituting the fluorine-based resin for aqueous coating compositions of the present invention, the presence of an emulsifier, and supplies the monomer mixture in the polymerization system, to perform the polymerization water-soluble initiator It is possible to use a method or a method using an inorganic peroxide and a redox type initiator of a reducing agent such as sodium thiosulfate. The method of supplying the monomer into the polymerization system is not particularly limited, and various conventionally known methods can be used.

After the emulsion obtained by the emulsion polymerization method is polymerized, a basic compound is added to bring the pH of the system to a neutral range to weakly alkaline, that is, a pH of 6.5 to 10.0, thereby stabilizing the system. You can improve your sex.

As the basic compound to be added, ammonia, triethylamine, propylamine, dibutylamine, amylamine, 1-aminooctane, 2-dimethylaminoethanol, ethylaminoethanol, 2-diethylaminoethanol, 1-amino-2- Propanol, 2-amino-1-propyl, 3-amino-1-propanol, 1-dimethylamino-2-propanol,
Examples thereof include 3-dimethylamino-1-propanol, 2-propylaminoethanol, ethoxypropylamine, aminobenzyl alcohol, morpholine, sodium hydroxide and potassium hydroxide.

Further, when it is necessary to adjust the molecular weight of the vinyl polymer, it is adjusted by using a chain transfer agent such as n-dodecyl mercaptan, t-dodecyl mercaptan or α-methylstyrene dimer as a molecular weight regulator. Is possible.

The fluorine-based resin for aqueous coating compositions of the present invention containing as the main component in this way was an emulsion obtained is to express a high level of performance as a coating material, various pigments, antifoaming agent Further, a pigment dispersant, a slip agent, an antiseptic agent, a plasticizer and the like can be added and used.

[0032] In forming a coating film on the surface of various materials by using a fluorine-based resin for aqueous coating compositions of the present invention, spray coating, roller coating, bar coating, air knife coating, brushing Method, dipping method, and other conventionally known various coating methods may be appropriately selected and performed.
There is no particular restriction.

[0033] In the case of using a fluorine-based resin for aqueous coating compositions of the present invention as a coating material, usually, room temperature to
A sufficiently film-formed coating film can be obtained by drying at a temperature range of about 120 ° C. for about 10 minutes to 1 hour.

[0034]

EXAMPLES The present invention will be described in more detail below with reference to examples. The compatibility and adhesion were evaluated by the following methods.

(1) Compatibility evaluation Fluororesin emulsion (manufactured by Asahi Glass Co., Ltd., trade name Lumiflon FE-3000 and Lumiflon FE-410)
0) and an acrylic emulsion were blended in a solid content ratio of 1: 1 and butyl cellosolve was added as a plasticizer in an amount of 10% by weight based on the total solid content, followed by thorough stirring to mix.
The mixed emulsion is filtered through 300 mesh nylon gauze, coated on a glass plate with an applicator (4ML), set at room temperature for 30 minutes, and dried at 80 ° C for 3 minutes.
It was dried for 0 minutes. After completion of drying, the transparency of the coating film was evaluated according to the following criteria and used as an index of compatibility. "C": The coating film after drying is completely transparent (compatibility is extremely good). “VHS”: The coating film after drying has a slight turbidity (good compatibility). "SH": The coating film after drying has more turbidity than VHS (compatibility is not very good). "H": The coating film after drying is cloudy (poor compatibility).

(2) Adhesion Evaluation 10 parts by weight of butyl cellosolve (based on solid content) as a plasticizer in an acrylic emulsion, and 3 parts by weight (based on solid content) of a thickener (manufactured by RHEOX, trade name RHEOLATE 350). After adding and stirring sufficiently, it was filtered with 300 mesh nylon gauze. Next, this acrylic emulsion was applied to a slate plate and a mortar plate to obtain a wet film thickness of 3
It was coated so as to have a thickness of 0 μm, set at room temperature for 30 minutes, and dried in a dryer at 80 ° C. for 30 minutes.

The dried coated plate was completely cooled to room temperature, and a fluororesin emulsion (Lumiflon FE-3000 and FE-4000 manufactured by Asahi Glass Co., Ltd., trade name) was compounded and filtered in the same manner as the above acrylic emulsion. The fluororesin emulsion thus obtained was coated on this coated plate (on the acrylic emulsion coating film of the slate plate and the mortar plate) so that the wet film thickness was 30 μm, and the coating was set at room temperature for 30 minutes, then at 80 ° C. 3 in the dryer
Dry for 0 minutes.

The coated plate for evaluation was cooled to room temperature completely, and the layer coated with the fluorine-based emulsion had a thickness of 2 mm.
100 corner cuts were made in a grid pattern, and a cellophane tape peeling test was performed 3 times at the same location, and the squares which were not peeled after the 3 times peeling test were counted.

Example 1 A polymerization container equipped with a stirrer, a cooler and a thermometer was charged with 60 parts by weight of deionized water, and the temperature was 60 ° C.
The temperature was raised to. Then, 100 parts by weight of the monomer mixture having the resin composition shown in Table 1, an emulsifier (surfactant) and deionized water 4
A pre-emulsion in a uniform emulsified state (hereinafter abbreviated as "PE liquid") was prepared by sufficiently mixing 0 parts by weight.

5 parts by weight of this PE solution was placed in a polymerization vessel and
The temperature was raised to 0 ° C., and when the internal temperature became stable, 0.1 parts by weight of sodium persulfate dissolved in 5 parts by weight of deionized water was added and left for 1 hour. After 1 hour, the rest of the PE solution and 0.2 parts by weight of sodium persulfate were added to 10 parts of deionized water.
What was melt | dissolved in weight part was dripped in the polymerization container over 3 hours, maintaining the internal temperature of a polymerization container at 80 degreeC, and after completion of dropping, the internal temperature of 80 degreeC was maintained for 2 hours, and reaction was completed. After the completion of the reaction, cooling was performed, the emulsion was taken out, and 28% aqueous ammonia was added so that the pH of the emulsion was between 7.5 and 10.

The solid content, pH, adhesion and compatibility with the fluororesin of the resulting acrylic emulsion are shown in Table 2.
Shown in.

[Examples 2 to 6 and Comparative Examples 1 to 4] Table 1
An acrylic emulsion was obtained in the same manner as in Example 1 except that the resin composition and the emulsifier shown in were changed. However, in Examples 3 to 5 and Comparative Example 1, 1.9 parts of adipic acid dihydrazide was added as a crosslinking agent.

The solid content, pH, adhesion and compatibility with the fluororesin of the resulting acrylic emulsion are shown in Table 2.
Shown in.

[0044]

[Table 1] Abbreviations in Table 1 indicate the following compounds.

[0045]   t-BMA: tertiary butyl methacrylate   t-BA: tertiary butyl acrylate   MMA: Methyl methacrylate   MAA: Methacrylic acid   AA: Acrylic acid   St: Styrene   n-BMA: normal butyl methacrylate   n-BA: normal butyl acrylate   IBXA: Isobornyl acrylate   CHMA: cyclohexyl methacrylate   2-EHA: 2-ethylhexyl acrylate   DAAm: diacetone acrylamide   HH: 2-methacryloyloxyethyl hexahydrophthalate (Mitsubishi Ayester Co., Ltd., trade name Acryester HH)   Sannor NP-2030: Surfactant manufactured by Lion Corporation   ABEX 23S: Surfactant manufactured by Rhodia Nika Co., Ltd.   ADEKA RIASOAP SE-10N: Surfactant manufactured by Asahi Denka Co., Ltd.

[0046]

[Table 2] As shown in Table 2, the aqueous coating compositions of Examples 1-6
It had excellent compatibility and adhesion with the fluororesin.

On the other hand, in Comparative Example 1, since the tertiary butyl (meth) acrylate as the component (a) and the ethylenically unsaturated carboxylic acid monomer as the component (b) were not used, a fluororesin was used. Was inferior in adhesion and compatibility. In Comparative Example 2, the component (b) and the component (c)
Since only the component (a) was used without using any component,
The stability required as an emulsion is insufficient,
A large amount of aggregates were generated at the time of blending the plasticizer and the like, and compatibility and adhesiveness could not be evaluated. In Comparative Example 3,
Since the component (a) was not used and the theoretical Tg was too high, the coating film was cracked at the stage of drying after coating the emulsion, and the adhesion could not be evaluated. In Comparative Example 4, the component (a) was used in a very small amount and the theoretical Tg
Is too low, the coated plate coated with emulsion has stickiness (tack) after drying. It was

[0048]

As described above, the aqueous coating composition of the present invention has excellent compatibility and adhesion with a fluororesin, and is excellent in transparency even when used by blending with a fluororesin. A film can be obtained, which can be favorably used as an intermediate coating material and an undercoating material when a coating material using a fluorine-based resin is used as a topcoat, which is extremely practical.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-283615 (JP, A) JP-A-10-265636 (JP, A) JP-A-4-359971 (JP, A) JP-A-9- 38568 (JP, A) JP 7-228826 (JP, A) JP 10-251590 (JP, A) JP 9-165533 (JP, A) JP 7-113063 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09D 1/00-10/00 C09D 101/00-201/10 C08J 7/04-7/06

Claims (5)

(57) [Claims] 1. (a) 5-80 parts by weight of tertiary butyl (meth) acrylate, (b) 0.1-10 ethylenically unsaturated carboxylic acid monomer.
Parts by weight, and (c) other ethylenically unsaturated monomers 10-94.9
Parts [(a) ~ (c) the total amount of 100 parts by weight of component] fluorine resin for aqueous coating composition characterized by containing an emulsion comprising a copolymer obtained from. 2. A copolymer according to claim 1 fluororesin for aqueous coating composition according theoretical glass transition temperature determined from the equation is -20 ° C. to 70 ° C. of Fox. 3. The emulsion according to claim 1, wherein the content of the surfactant in the emulsion is in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the total of the components (a) to (c). fluorine-based resin for aqueous coating compositions. 4. The fluororesin according to claim 1, wherein a monomer represented by the following general formula (I) is used as the component (b).
Use aqueous coating composition. ^{_{CH 2 = CR 1 -COO-C}} 2 H 4 -OC (O) -R 2 -C
OOH (I) (In the formula, R ¹ represents H or CH ₃ , and R ² has 2 to 2 carbon atoms.
28 groups are shown. ) 5. An organic hydrazine derivative having 2 or more hydrazine residues in an aqueous medium of an emulsion, wherein 1 to 10 parts by weight of a carbonyl group- or aldehyde group-containing vinyl monomer is used as the component (c). fluorine-based resin for aqueous coating composition according to claim 1, wherein the inclusion.