JPH07165833A - Acrylate polymer and thermosetting composition containing the same - Google Patents

Abstract

PURPOSE:To obtain an acrylate polymer excellent in solvent solubility, hardness of cured resin, and dryability of coating film by homopolymerizing or copolymerizing 2-hydroxycyclohexyl (meth)acrylate. CONSTITUTION:This polymer is hydroxylated acrylate polymer containing 3-100wt.% structural units of the formula and having a number-average molecular weight of 1500-7000. It is a homopolymer or copolymer obtained by polymerizing 2-hydroxy-cyclohexyl (meth)acryate optionally with other polymerizable monomers. 2-hydroxycyclohexyl (meth)acrylate as the starting material is obtained by, e.g. a reaction of cyclohexane oxide with (meth)acrylic acid or an esterification reaction of 1,2-cyclohexanediol with (meth)acrylic ester.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel acrylic polymer used in the fields of paints, adhesives, coating agents and the like, and a thermosetting composition using the same.

[0002]

2. Description of the Related Art A curable resin comprising an acrylic resin, a polyester resin, an epoxy resin having a hydroxyl group and a curing agent capable of reacting with the hydroxyl group to form a crosslink is
It is widely used and used in various fields. In particular, a thermosetting composition comprising a hydroxyl group-containing acrylic copolymer (hereinafter referred to as an acrylic polyol) and a polyisocyanate-based or melamine-based curing agent has a solid position in the fields of paints, coating agents, adhesives, etc. I'm building. However, as the acrylic monomer to be the hydroxyl source of these acrylic polyols, currently, only relatively limited ones such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate are generally available. Is. On the other hand, when the above 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate are incorporated into acrylic polyol as a copolymerization component, the solvent solubility of the acrylic polyol, the hardness of the cured resin, the cured coating, and the like. It often adversely affects various physical properties such as the drying property of the film.

[0003]

Therefore, in the art, it has been desired to develop an acrylic polyol and a thermosetting composition which are excellent in solvent solubility, hardness of a cured resin, and dryness of a cured coating film.

[0004]

Means for Solving the Problems As a result of studies in view of the above problems, the present inventors have an acrylic polymer having a hydroxyl group, which has a specific constituent component and a specific molecular weight,
Further, they have found that the above problems can be solved by a composition containing the polymer and a curing agent as essential components, and completed the present invention.

That is, the present invention comprises an acrylic polymer containing 3 to 100% by weight of the structural unit represented by the general formula (I) and having a number average molecular weight of 1500 to 70,000, and (A).
The present invention relates to a thermosetting composition comprising the polymer and (B) a curing agent capable of reacting with a hydroxyl group to form a crosslink, as essential components.

[0006]

[Chemical 2]

The acrylic polymer of the present invention comprises 2-hydroxycyclohexyl (meth) acrylate alone,
Alternatively, it is a homopolymer or a copolymer obtained by polymerizing with other polymerizable monomers as required. 2-hydroxycyclohexyl (meth) acrylate, which is the raw material, is, for example, cyclohexene oxide and (meth)
Reaction with acrylic acid, esterification reaction between 1,2-cyclohexanediol and (meth) acrylic acid, transesterification reaction between 1,2-cyclohexanediol and (meth) acrylic acid ester, or 1,2-cyclohexanediol And (meth) acrylic acid halide.

Further, as the hydroxyl group source of the acrylic polymer of the present invention, along with the above-mentioned 2-hydroxycyclohexyl (meth) acrylate, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and the like are known. The hydroxyl group-containing monomer can also be used together. Other copolymerizable monomers that can be used as necessary include, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, -n-butyl acrylate, cyclohexyl acrylate, -n-octyl acrylate, and acrylic. Acrylic acid esters such as 2-ethylhexyl acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, -n-butyl methacrylate, isobutyl methacrylate, -n-hexyl methacrylate, cyclohexyl methacrylate, methacrylic acid-n -Methacrylic acid esters such as octyl, 2-ethylhexyl methacrylate, lauryl methacrylate, glycidyl methacrylate, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamide, n-meth Unsaturated amides such as roll acrylamide and diacetone acrylamide, chloroolefins such as vinyl chloride and vinylidene chloride, fluoroolefins such as terrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride and hexafluoropropylene, acrylonitrile and methacrylonitrile. Nitrile group-containing monomers such as, vinyl ethers such as ethyl vinyl ether, n-butyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, carboxylic acid vinyl esters, and styrene, styrene derivatives, vinyltoluene, vinyl acetate, etc. These may be used alone or in combination of two or more.

The polymerization can be arbitrarily selected from known methods such as solution polymerization, emulsion polymerization and suspension polymerization as a polymerization mode, and radical polymerization and ionic polymerization as a polymerization mechanism according to the purpose. It is possible. In the case of application to the field of paints, adhesives, coating agents, etc., which is one of the purposes of the present invention, it is preferable to obtain the target polymer by radical polymerization by a solution polymerization or emulsion polymerization technique.

In the resulting polymer, the content of the structural unit represented by the general formula (I) must be 3% by weight or more. When the content is less than 3% by weight, the crosslinking property is poor, the compatibility with a solvent, the pigment dispersibility, the effect of improving various physical properties such as the hardness of a cured resin and the drying property of a cured coating film are poor, and thus it is preferable. Absent. The content of the structural unit represented by the general formula (I) is preferably 5 to 70% by weight, more preferably 8 to 50% by weight.

The number average molecular weight of the obtained polymer is 1
It must be 500 to 70,000. When the number average molecular weight is less than 1500, various properties such as hardness of the cured resin are adversely affected, and when it exceeds 70000, the viscosity in a solution state is too high and it is difficult to handle. The preferred number average molecular weight of this polymer is 2
000 to 50,000, more preferably 3000 to 500
00.

A curable resin composition is obtained by combining the thus obtained acrylic polymer having a hydroxyl group with a curing agent capable of reacting with the hydroxyl group to form a crosslink. Typical examples of these curing agents include polyisocyanate-based curing agents that form urethane bonds and melamine-based curing agents that form ether bonds.

Examples of polyisocyanate type curing agents include 2,4- or 2,6-tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI),
Diisocyanate monomers such as 1,6-hexamethylene diisocyanate (HDI), 2,2,4-
Or 2,4,4-trimethylhexamethylene diisocyanate (TMDI), lysine diisocyanate, 3-isocyanatomethyl-3,3,5-trimethylcyclohexyl isocyanate (IPDI), 1,3- or 1,4
-Bis (isocyanatomethyl) -cyclohexane (hydrogenated XDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI) and other aliphatic / alicyclic diisocyanate monomers, and further these diisocyanate monomers are buretted. Examples thereof include polyisocyanates oligomerized by a bond, a urea bond, an isocyanurate bond, a urethane bond, an allophanate bond, a uretdione bond and the like. Further, so-called blocked isocyanates obtained by masking the isocyanate groups of these diisocyanate monomers and polyisocyanates with a thermally dissociative protective group can also be used as a curing agent.

These polyisocyanate curing agents can be freely selected according to the purpose and can be used in combination, but since diisocyanate monomers generally have a vapor pressure, they are oligomerized from the viewpoint of safety and hygiene. The use of isocyanates is preferred. Further, in the case where the cured resin is required to have weather resistance, it is preferable to use polyisocyanates derived from the above aliphatic / alicyclic diisocyanates.

The mixing ratio of the hydroxyl group-containing acrylic polymer and the polyisocyanate curing agent is 5/1 to 1/2, preferably 2/1 to 2 in terms of the equivalent ratio of OH groups / NCO groups.
It is desirable to set it to about / 3. If the equivalent ratio exceeds 5/1 and the number of hydroxyl groups is excessive, the cured product will have poor solvent resistance, and if it exceeds 1/2 and the amount of isocyanate groups will be excessive, the mechanical strength of the cured product will deteriorate. Is not preferred.

Examples of the melamine type curing agent include a completely alkyl type methylated melamine represented by hexamethoxymethylated melamine, hexabutoxymethylated melamine, methoxybutoxy mixed methylated melamine, etc., an alkyloxy group and a methylol group. Examples thereof include methylol group-type methylated melamine, and imino group-type methylated melamine having an alkyloxy group and an imino group. Further, a guanamine-based compound such as benzoguanamine modified by alkyloxymethylation as described above can also be used as a curing agent.

These melamine-based curing agents can be freely selected according to the purpose and can be used in combination. The compounding ratio of the acrylic polymer having a hydroxyl group and the melamine-based curing agent can be selected relatively freely, but generally, the weight ratio of the acrylic polymer and the melamine-based curing agent is 2
The range of about 0: 1 to 1: 1 is preferable.

The thermosetting composition thus obtained is cross-linked and cured even at room temperature when a polyisocyanate curing agent is used, and is generally heated at 60 to 220 ° C. when a blocked isocyanate or melamine type curing agent is used. Since it can be crosslinked and cured, it can be widely applied to the fields of paints, adhesives, coating agents and the like. Of course, solvents, pigments, fillers, various additives, other resins and the like can be added and blended according to these uses and purposes.

[0019]

EXAMPLES Next, the present invention will be described in more detail by way of examples.

[0020]

Example 1 A flask equipped with a thermometer, a stirrer, a reflux condenser and a dropping funnel was charged with 25 g of toluene and 25 g of butyl acetate, and the mixture was heated with stirring at 80 ° C. 2-hydroxycyclohexyl methacrylate 16.
0 g, methyl methacrylate 50.0 g, acrylic acid-n
-Butyl 34.0 g, toluene 25 g, butyl acetate 25
g and azobisisobutyronitrile (4.0 g) were charged, and the mixture was gradually added dropwise to the flask over 2 hours. Furthermore,
The mixture was heated and stirred at 80 ° C. for 4 hours to complete the polymerization reaction. The molecular weight of the obtained acrylic copolymer was 11,500 by GPC analysis.

[0021]

Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that 2-hydroxyethyl methacrylate was used instead of 2-hydroxycyclohexyl methacrylate.
As a result, the obtained acrylic copolymer had a molecular weight of GPC.
According to the analysis, the number average molecular weight was 8700.

[0022]

Example 2 The acrylic copolymer solution obtained in Example 1 was heated under reduced pressure to remove the solvent, and then the solid content was 30% by weight with a toluene / butyl acetate mixed solution (weight ratio 1/1). So diluted. When 1 g of the diluted solution was placed in a sample bottle and Mineral Spirit (manufactured by Shell Kagaku Co., Ltd.), which is a low-polarity solvent, was gradually added thereto, it became cloudy at 0.571 g. Similarly, when Swasol 310 (manufactured by Maruzen Petrochemical Co., Ltd., aromatic hydrocarbon mixture) was used as a low-polarity solvent, it was clouded at 0.918 g. Solubility in low-polarity solvents is expressed by the dilutable ratio according to the following formula, and Table 1
It was shown to.

Dilutable ratio = (amount of low-polarity solvent (g) before becoming cloudy) / (amount of sample liquid (g))

[0024]

COMPARATIVE EXAMPLE 2 The procedure of Example 2 was repeated except that the acrylic copolymer liquid obtained in Comparative Example 1 was used. When 0.148 g of mineral spirit and 0.148 g of Swazol 310 were added, white turbidity occurred. The calculation result of the dilutable ratio is shown in Table 1.

[0025]

Example 3 Acrylic copolymer solution 1 obtained in Example 1
Duranate TPA as a curing agent (0.0 g, manufactured by Asahi Chemical Industry Co., Ltd., hexamethylene diisocyanate-based polyisocyanate, isocyanurate type, NCO% 23.1)
wt%) 0.73 g. This mixed solution was applied to a test piece and cured by heating at 140 ° C. for 2 hours. The results of measuring various physical properties of the cured coating film are shown in Table 2.

[0026]

[Example 4] Example 3 except that the curing reaction between the acrylic copolymer and the curing agent was performed at a temperature of 20 ° C and a humidity of 60 RH%.
A cured coating film was obtained in the same manner as in. The results of measuring various physical properties of the cured coating film are shown in Table 3.

[0027]

Comparative Example 3 Acrylic copolymer solution 1 obtained in Comparative Example 1
0.0g and 1.05g of Duranate TPA as a curing agent
Was mixed and a cured coating film was obtained in the same manner as in Example 3. The results of measuring various physical properties of the cured coating film are shown in Table 2.

[0028]

Comparative Example 4 Comparative Example 3 except that the curing reaction between the acrylic copolymer and the curing agent is performed at a temperature of 20 ° C. and a humidity of 60 RH%.
A cured coating film was obtained in the same manner as in. The results of measuring various physical properties of the cured coating film are shown in Table 3. The tests in Tables 2 and 3 were performed according to the following method. (1) Gel Fraction The cured coating film is dipped in acetone at 20 ° C. for 24 hours, taken out, and dried at 50 ° C. for 1 hour to remove acetone.
At this time, the insoluble matter in acetone was represented by the residual weight ratio of the coating film, and was defined as the gel fraction. (2) Glass transition temperature The dynamic viscoelasticity of the cured coating film was measured with Toyo Baldwin's Rheovibron DDV-01FP type at a measurement frequency of 11
The glass transition temperature was determined from the peak of tan δ at that time. (3) Adhesiveness JIS K 54 using an aluminum plate as a test plate
00, the adhesion of the cured coating film was evaluated according to the cross-cut tape method. (4) Bending resistance JIS K 54 using an aluminum plate as a test plate
The crack resistance of the cured coating film was evaluated in accordance with No. 00. (5) Gloss The 60 degree specular gloss of the coating film surface was measured according to JIS Z 8741. (6) Pencil hardness The pencil scratch value was determined according to JIS K 5400. (7) Dryability Five layers of gauze are placed on the surface of the coating film, and a weight of 100 g is placed thereon for 1 minute. After this, the gauze was removed, and the drying property of the coating film was evaluated at the time when no gauze marks were left. (8) Pot life Acrylic copolymer and curing agent mixed solution at 20 ° C., 60 RH%
Was stored in the container and expressed as the time until it stopped flowing in the container.

[0029]

Example 5 In a test tube, 1.01 g of 2-hydroxycyclohexyl methacrylate, 0.042 g of azobisisobutyronitrile, 0.56 g of toluene, and 0.
51 g was added and heated at 80 ° C. for 30 minutes. The produced acrylic polymer was vacuum-dried at 120 ° C. and 1 mmHg to remove the solvent, and then measured by a differential scanning calorimeter DSC-200 manufactured by Seiko Denshi Kogyo Co., Ltd., and the glass transition point of this acrylic polymer was 123. It was ℃. The number average molecular weight by GPC analysis was 40,000.

[0030]

Comparative Example 5 An acrylic polymer was synthesized in the same manner as in Example 5 except that 2-hydroxyethyl methacrylate was used instead of 2-hydroxycyclohexyl methacrylate. The glass transition point of the obtained acrylic polymer was 87 ° C. Moreover, the number average molecular weight by GPC analysis was 51,000.

[0031]

Example 6 16 g of toluene and 13 g of butyl acetate were charged into a flask equipped with a thermometer, a stirrer, a reflux condenser and a dropping funnel, and the mixture was heated and stirred at 80 ° C. 2-hydroxycyclohexyl acrylate 11.0 on the dropping funnel
g, methyl methacrylate 27.0 g, acrylic acid-n-
Butyl 22.0 g, Toluene 16 g, Butyl acetate 13
After charging 2.4 g of azobisisobutyronitrile, the mixture was gradually added dropwise to the flask over 2 hours. Furthermore,
The mixture was heated and stirred at 80 ° C. for 4 hours to complete the polymerization reaction. The obtained acrylic copolymer had a number average molecular weight of 87,000 by GPC analysis.

[0032]

Comparative Example 6 The reaction was carried out in the same manner as in Example 6 except that 2-hydroxyethyl acrylate was used instead of 2-hydroxycyclohexyl acrylate. As a result, the molecular weight of the obtained acrylic copolymer was 9,000 by GPC analysis.

[0033]

Example 7 The procedure of Example 2 was repeated except that the acrylic copolymer liquid obtained in Example 6 was used. Mineral spirit: 1.07 g; Swazol 310: 2.
It turned cloudy when 04 g was added. The calculation result of the dilutable ratio is shown in Table 1.

[0034]

COMPARATIVE EXAMPLE 7 The procedure of Example 2 was repeated except that the acrylic copolymer liquid obtained in Comparative Example 6 was used, with 0.30 g of mineral spirit and 0.
It became cloudy when 45 g was added. The calculation result of the dilutable ratio is shown in Table 1.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain an acrylic polyol, a curable resin, and a coating which are excellent in solvent solubility, hardness of a cured resin, and dryness of a cured coating film, and their industrial value is extremely high. high.

Claims (4)

[Claims] 1. A structural unit represented by the general formula (I) is 3 to.
100% by weight and number average molecular weight of 1500-7
An acrylic polymer having 0000 hydroxyl groups. [Chemical 1] 2. The hydroxyl group-containing acrylic polymer according to claim 1, wherein the content of the structural unit represented by the general formula (I) is 3 to 80% by weight. 3. A structural unit represented by the general formula (I) (A) is contained in an amount of 3 to 100% by weight and a number average molecular weight of 150.
An acrylic polymer having a hydroxyl group of 0 to 70,000;
A thermosetting composition comprising (B) a curing agent capable of reacting with a hydroxyl group to form a crosslink, as an essential component. 4. A structural unit represented by the general formula (I) (A) is contained in an amount of 3 to 80% by weight and a number average molecular weight of 1500.
An acrylic polymer having ˜70,000 hydroxyl groups,
A thermosetting composition comprising (B) a curing agent capable of reacting with a hydroxyl group to form a crosslink, as an essential component.