JPS6221005B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an acrylic resin for solvent-based coatings that has excellent flexibility, elasticity, weather resistance, hardness, adhesion, pigment dispersibility, etc. Lacquers whose main component is methyl methacrylate polymer have excellent transparency, gloss retention, and weather resistance, but they tend to crack due to temperature changes and swelling and shrinking effects due to moisture, and have defects in impact resistance and adhesion. It is known that there is. In order to improve these drawbacks, a method of plasticizing the copolymer by partially substituting higher alkanol with acrylate or methacrylate has been widely used.
However, with this method, it is difficult to obtain a coating film with well-balanced physical properties such as weather resistance, crack resistance, flexibility, elasticity, and adhesion. That is, as the proportion of higher alkanol acrylate or methacrylate copolymerized with methyl methacrylate is increased, flexibility, crack resistance, and painting workability are improved, but thinner resistance and hardness are decreased, and in particular, weather resistance and flexibility are improved. It is unsuitable for applications that require strength, elasticity, crack resistance, thinner resistance, etc. In addition, as a water-dispersed varnish for electrodeposition, 25 to 50 parts of acrylonitrile, 50 to 75 parts of methacrylic acid ester,
Products made by emulsion copolymerization of 2 to 10 parts of methacrylic acid are also known, but coatings obtained using solvent-based coating acrylic resins with such a monomer composition generally have good weather resistance and adhesion. However, it has the disadvantage that the pigment dispersibility of the paint itself is poor. The present invention provides an acrylic resin for solvent-based coating that has improved these drawbacks. That is, in the present invention, in the presence of an organic solvent, (a) n-butyl methacrylate 30 to 99.4% by weight, (b) acrylonitrile 0.5 to 30% by weight, (c) unsaturated acid 0.1 to 5% by weight,
(d) 1 to 20% by weight of an unsaturated bond-containing polyester resin, (e) 0 to 25% by weight of a polymerizable monomer having one or more hydroxyl groups in one molecule, and (f) the above (a) to ( Consists of 0 to 69.4% by weight of other vinyl monomers that can be copolymerized with component e), and the total amount of each monomer is 100% by weight.
A method for producing an acrylic resin for solvent-based coatings with good flexibility and a glass transition point of -10°C to 40°C and a number average molecular weight of 5,000 to 100,000, which comprises copolymerizing a monomer mixture of It provides: Among the components constituting the acrylic resin of the present invention,
The components (a) n-butyl methacrylate, (b) acrylonitrile, and (c) unsaturated acid are essential components for imparting flexibility, elasticity, weather resistance, hardness, and adhesion to the resulting resin. On the other hand, the unsaturated bond-containing polyester resin component (d) is a necessary component for improving the dispersibility of the pigment. The usage range of each of these components is (a) n-butyl methacrylate 30-99.4% by weight, (b) acrylonitrile 0.5-30% by weight, (c) unsaturated acid 0.1-5% by weight, (d) unsaturated bond-containing polyester. Resin ranges from 1 to 20% by weight, preferably (a)30
A suitable range is 97.5% by weight, (b) 2-25% by weight, and (c) 0.5-2.5% by weight. However, the total of each of these essential monomer components shall always be 100% by weight. In the present invention, the acid component included in the term unsaturated acid refers to acid components provided in coating resins such as (meth)acrylic acid, itaconic acid, fumaric acid, and (anhydrous) maleic acid. In addition to the above-mentioned essential components of (a) n-butyl methacrylate, (b) acrylonitrile, (c) unsaturated acid, and (d) unsaturated bond-containing polyester resin, the present invention also includes an acrylic resin for coating. Further addition of various components for the purpose of improving membrane performance.
can be used. That is, as necessary, the constituent components of the acrylic resin of the present invention include (e) a polymerizable monomer having one or more hydroxyl groups in one molecule, (f) the above-mentioned (a)-
Examples include other vinyl monomers that can be copolymerized with component (e). As the unsaturated bond-containing polyester resin (d),
Drying oil and/or semi-drying oil alkyd resins having a number average molecular weight in the range of 500 to 10,000 and unsaturated oil-free alkyd resins having a hydroxyl equivalent weight of 300 to 600 can be used. Polyhydric alcohols that can be used to produce such unsaturated bond-containing polyester resins include (poly)ethylene glycol, (poly)propylene glycol, neopentyl glycol,
1,6-hexanediol, 1,3-butylene glycol, 1,4-butylene glycol, bis(hydroxyethyl) terephthalate, hydrogenated bisphenol A, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, etc. Monovalent carboxylic acids and polyvalent carboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, hettic acid, trimellitic acid, succinic acid,
Oxalic acid, adipic acid, sebacic acid, benzoic acid,
Examples include p-tert-butylbenzoic acid, p-hydroxybenzoic acid and its anhydride. Additionally, drying and semi-drying oils include linseed oil,
Examples include tung oil, safflower oil, dehydrated castor oil, cottonseed oil, soybean oil, rice bran oil, etc. When synthesizing by the fatty acid method, fatty acids of these oils and tall oil fatty acids can be used. Unsaturated dicarboxylic acids include (anhydrous) maleic acid, fumaric acid, itaconic acid, citraconic acid, and tetrahydrophthalic anhydride. The unsaturated bond-containing polyester resin used in the present invention can be obtained by calculating the composition of any combination of these raw materials and reacting them by a known method, but the grafting with polymerizable monomers in the next step Considering the drying conditions, the oil length of drying oil and/or semi-drying oil alkyd resin is from 30 to
80%, the unsaturated dicarboxylic acid of the unsaturated oil-free alkyd resin is preferably used in the range of 0.5 to 5% by weight. The amount of the unsaturated bond-containing polyester resin (d) used is preferably in the range of 1 to 20% by weight. In addition, the polymerizable monomer (e) having one or more hydroxyl groups in one molecule is mainly polyisocyanate,
25% by weight or less as an essential component when used in combination with a crosslinking component such as aminoplast to make a curable paint.
It is preferably used in a range of 5 to 25% by weight. Monomer (e) includes β-hydroxyethyl (meth)acrylate, β-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, trimethylolpropane, glycerin (meth)acrylate. Examples include acid monoesters. Furthermore, other vinyl monomers (f) that can be copolymerized with each of the components (a) to (e) described above include styrene, vinyltoluene, methyl (meth)acrylate, ethyl (meth)acrylate, and isopropyl. (meta)
Acrylate, n-butyl acrylate, iso-
Butyl (meth)acrylate, tert-butyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, (methyl)glycidyl (meth)acrylate , dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc., and the amount of these used depends on coating film performance such as coating workability, gloss, flexibility, hardness, weather resistance, drying property, and solvent resistance. When it is further improved depending on the intended use, it is used in a range of 0 to 69.5% by weight. The synthesis of the acrylic resin for coating of the present invention is as described above.
This can be easily accomplished by synthesizing components (a) to (f) according to known techniques. Polymerization initiators used in the reaction include azobisisobutyronitrile, benzoyl peroxide, tert-butyl perbenzoate, tert-butyl hydroperoxide, di-tert-butyl peroxide, kyumene hydroperoxide, etc. is appropriate,
It is used in an amount of 0.1 to 5% by weight based on the total amount of components constituting the resin. Here, examples of organic solvents include aromatic solvents such as toluene and xylene;
Ester types such as ethyl acetate, butyl acetate, and cellosolve acetate, ketone types such as methyl ethyl ketone and methyl isobutyl ketone, butanol,
Alcohol solvents such as isobutanol and butyl cellosolve alone or in combination are suitable. The number average molecular weight of the coating acrylic resin obtained by the method of the present invention is 5,000 to 100,000, and when considering the firmness of the paint film after painting, workability during spray painting, etc., the range is 5,000 to 40,000. preferable. On the other hand, the glass transition temperature of the coating acrylic resin obtained by the method of the invention is also an important factor for the cured coating when the acrylic resin is used, for example, in lacquer-type and curable coatings. Therefore, the glass transition temperature, which is the temperature at which the polymer molecule segments of the acrylic resin change from a fixed state, that is, a glass state, to a state where these polymer molecule segments can move, that is, a rubber state, is, for example, a glass transition temperature. For mold coatings, the appropriate range is 0 to 40°C, preferably 5 to 38°C; for example, for curable coatings, it is -10 to +30°C, preferably -10 to +20°C. Within this range is appropriate. Among these, Lutzker-type coatings with a glass transition point of less than 0°C have extremely poor staining properties at room temperature;
If the temperature exceeds 40℃, the elongation will be poor.
On the other hand, a cured coating film with a glass transition point of less than -10°C has extremely poor staining properties when used in combination with a soft crosslinking agent such as an aliphatic polyisocyanate; If the temperature exceeds 30°C, the glass transition point of the cured coating film itself will exceed 40°C when used in combination with a hard crosslinking agent such as melamine resin, which is preferable since the cured coating film will only be extremely brittle. do not have. The acrylic resin for coating of the present invention has the above-mentioned (a) to
Component (f) is prepared by known and commonly used means,
(Weight average molecular weight of the acrylic resin...
)/(number average molecular weight...... _N ) ratio is 3
It is best to adjust it so that it is in the range of ~20. That is, for example, one of the measures to improve pigment dispersibility is to prevent pigments from agglomerating together, but in order to do this, it is necessary to efficiently adsorb the acrylic resin to the pigment surface and to absorb the polymer particles that are the acrylic resin. Prevention of aggregation due to steric hindrance is required. As one such method, the present inventors have used these /
It has also been found that it is effective to keep the _N ratio within the above range. In order for the ratio of / to be in the range of 3 to 20, the ratio of the relatively high molecular weight part to the relatively low molecular weight part is a major factor, so how to create both parts is a major factor. This is an important point. Generally speaking, to create a high molecular weight part, the reaction should be carried out with less initiator and high monomer concentration, while to create a low molecular weight part, the reaction should be carried out under the opposite reaction conditions. A desired ratio of / may be selected by combining these synthesis conditions. The acrylic resin for coating of the present invention includes vinyl resin,
Used in combination with alkyd resin, nitrocellulose, etc. as a lacquer-type paint, or by incorporating a functional monomer into the copolymer and used in combination with a crosslinking agent such as polyisocyanate, amino resin, epoxy resin, etc. as a curable paint. can. Furthermore, the paint can be used as a clear paint or an enamel paint using known pigments. The resulting paint can be applied using commonly used methods such as spray painting, brush painting, and roller painting, and can be cured using drying at room temperature, forced drying, baking drying, and far infrared rays. An appropriate method such as drying can be selected. The acrylic resin for coating obtained by the present invention has well-balanced properties such as weather resistance, crack resistance, hardness, adhesion, and flexibility, and has particularly good flexibility. There are characteristics. Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to what is described in the Examples. "Parts" in the examples indicate "parts by weight." Reference Example 1 (Manufacture of unsaturated bond-containing polyester resin) Add linseed oil to a four-necked flask equipped with a stirrer, thermometer, air condenser, and nitrogen inlet tube.
500 parts, 105.8 parts of glycerin, and 0.125 parts of Resurge, and after transesterifying at 240℃ for 1 hour,
The mixture was cooled to .degree. C., and 82.4 parts of glycerin and 364.1 parts of phthalic anhydride were added thereto, followed by reaction at 230.degree. C. for 10 hours in a nitrogen stream. The product was diluted to 50% non-volatile content as an organic solvent, Gardner viscosity (25°C) B-C, acid number 3.6,
A linseed oil alkyd resin solution with a number average molecular weight of 8800 and an oil length of 50% was obtained. Reference Example 2 (Production of unsaturated bond-containing polyester resin) Isophthalic acid was placed in a four-necked flask equipped with a stirrer, thermometer, air condenser, and nitrogen inlet tube.
440 parts of adipic acid, 177.5 parts of adipic acid, 361 parts of neopentyl glycol, 181.3 parts of trimethylolpropane, and 15 parts of maleic anhydride were charged, and the mixture was heated to 220 parts in a nitrogen stream.
The reaction was carried out at a temperature of about 10 hours to obtain a resin having an acid value of 8, an OH value of 132, a hydroxyl equivalent of 425, and a number average molecular weight of 1,600. When this was diluted to a non-volatile content of 60% with a mixed organic solvent of toluene:butyl acetate=50:50 (weight ratio), it had a Gardner viscosity of H, an acid value of 4.8, an OH value of 79.2, and a color number of 2. Example 1 First, 400 parts of n-butyl methacrylate, 100 parts of acrylonitrile, 100 parts of methyl methacrylate
parts, ethyl acrylate 260 parts, methacrylic acid 10 parts
950 parts of a monomer mixture consisting of 950 parts of
Add toluene to a four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube.
950 parts, 300 parts of the above monomer mixture, 100 parts of the alkyd resin solution of Reference Example 1, and 1 part of benzoyl peroxide were charged, and the temperature was raised to 80°C.
After holding for 2 hours at
10 parts of benzoyl peroxide was added dropwise over 4 hours, and after the completion of the dropwise addition, the polymer was maintained for 8 hours to obtain a polymer with non-volatile content of 49.1%, Gardner viscosity Z, Tg of 26°C, number average molecular weight of 17000, / _N = 5.2. Ta. Example 2 First, 900 parts of a monomer mixture consisting of 400 parts of n-butyl methacrylate, 100 parts of acrylonitrile, 180 parts of styrene, 210 parts of n-butyl acrylate, and 10 parts of methacrylic acid was prepared.
933 parts of toluene, 400 parts of the above monomer mixture, 167 parts of the oil-free alkyd resin obtained in Reference Example 2, and 1 part of benzoyl peroxide were placed in a reaction vessel similar to the above, and the temperature was raised to 80°C. ,80℃
After holding for 2 hours, the remaining monomer mixture 500
10 parts of benzoyl peroxide was added dropwise over 4 hours, and after the dropwise addition was completed, the polymer was kept for 8 hours to obtain a polymer with non-volatile content of 50.5%, Gardner viscosity X, Tg 17°C, number average molecular weight 15000, / _N = 6.5. . Example 3 450 parts of n-butyl methacrylate, 100 parts of acrylonitrile, 92 parts of β-hydroxyethyl methacrylate, 100 parts of methyl methacrylate, n
-198 parts of butyl acrylate and methacrylic acid
Prepare 950 parts of a monomer mixture consisting of 10 parts, and add 100 parts of the alkyd resin of Reference Example 1, 950 parts of toluene, and 300 parts of the above monomer mixture to the same reaction vessel as in Example 1. 1 part of the monomer mixture and 1.0 part of benzoyl peroxide were charged, the temperature was raised to 80°C, kept at the same temperature for 2 hours, and then the remaining monomer mixture was added.
650 parts of benzoyl peroxide and 10 parts of benzoyl peroxide were added dropwise over a period of 4 hours, and the mixture was kept for 8 hours after the addition was complete. Non-volatile content was 50.5%, Gardner viscosity Z ₂
A polymer with a Tg of 15°C and a number average molecular weight of 23,000 was obtained. Example 4 A monomer mixture consisting of 720 parts of n-butyl methacrylate, 100 parts of methyl methacrylate, 150 parts of acrylonitrile and 10 parts of methacrylic acid was prepared in advance.
Prepare 980 parts, and add 40 parts of the alkyd resin of Reference Example 1, 980 parts of toluene, 300 parts of the above monomer mixture, and 1.0 part of benzoyl peroxide to the same reaction vessel as in Example 1. After charging and raising the temperature to 80℃ and keeping it at the same temperature for 2 hours, 680 parts of the remaining monomer mixture and 10 parts of benzoyl peroxide were added dropwise over 4 hours, and the temperature was maintained for 8 hours even after the dropwise addition was completed. Then, non-volatile content 50.2%, Gardner viscosity Z ₁ , Tg 38℃, number average molecular weight 20000, /
= 4.0 was obtained. Example 5 A monomer mixture consisting of 590 parts of n-butyl methacrylate, 150 parts of methyl methacrylate, 100 parts of acrylonitrile and 10 parts of methacrylic acid was prepared in advance.
Prepare 850 parts, and add 300 parts of the alkyd resin of Reference Example 1, 850 parts of toluene, 300 parts of the above monomer mixture, and 1.0 part of benzoyl peroxide to the same reaction vessel as in Example 1. Prepare and heat to 80℃
After raising the temperature to 2 hours and keeping it at the same temperature for 2 hours, 550 parts of the remaining monomer mixture and 10 parts of benzoyl peroxide were added dropwise over 4 hours. min 50.6%, Gardner viscosity X, Tg35℃, number average molecular weight 18000,
A polymer with /=4.9 was obtained. Comparative Example 1 Same as Example 1 except that 1050 parts of a monomer mixture consisting of 400 parts of acrylonitrile, 600 parts of ethyl methacrylate and 50 parts of methacrylic acid was used, non-volatile content 51.3%, Gardner viscosity Z ₃ , a control polymer having a Tg of 83°C and a number average molecular weight of 21,000 was obtained. Comparative Example 2 Same as Example 1, except that 1000 parts of a monomer mixture consisting of 658 parts of methyl methacrylate, 332 parts of n-butyl acrylate, and 10 parts of methacrylic acid was used, with a non-volatile content of 50.6%,
Gardner viscosity Z ₁ , Tg30℃, number average molecular weight 23000
A control mixture was obtained. Comparative Example 3 A nonvolatile sample was prepared in the same manner as in Example 1, except that 1000 parts of a monomer mixture consisting of 150 parts of acrylonitrile, 508 parts of methyl methacrylate, 332 parts of n-butyl acrylate, and 10 parts of methacrylic acid was used. min 50.3%, Gardner viscosity Z−Z ₁ ,
A polymer with a Tg of 30°C and a number average molecular weight of 24,000 was obtained. The results of testing the copolymers obtained as described above are shown in Tables 1 and 2. [Test on coating film performance] Titanium oxide was weighed out so that the pigment content was 40% based on 100 parts of each polymer, and thinner was added to it.
40 parts of xylene:butyl acetate = 50:50 and 250 parts of glass beads were added and kneaded in a sand mill for 1 hour, after which the glass beads were passed through to form a base. This base was further diluted with thinner, and the viscosity was adjusted to 18 to 20 seconds using a food cup No. 4. This was applied to a tin plate and dried for one week at room temperature. However, in Example 5, "Burnock DN-950" (manufactured by Dainippon Ink Chemical Industries, Ltd.,
Polyisocyanate) was used so that OH/NCO=1.0 (equivalent ratio), and after painting, it was treated under the same drying conditions (1 week at room temperature).

[Test on pigment dispersibility]

For 100 parts of each polymer, weigh out the pigment so that it has the pigment content (PWC) listed in Table 2, add 40 parts of thinner and 250 parts of glass beads, and knead in a sand mill for 1 to 3 hours. After this, glass beads were passed through to obtain a color base.

【table】

【table】

Claims (1)

[Claims] 1 In the presence of an organic solvent, (a) 30-99.4% by weight of n-butyl methacrylate, (b) 0.5-30% by weight of acrylonitrile, and (c) 0.1-5% by weight of an unsaturated acid.
and (d) 1 to 20 of the unsaturated bond-containing polyester resin.
(e) 0 to 25% by weight of a polymerizable monomer having one or more hydroxyl groups in one molecule; and (f) the above (a) to (e).
0 to 0 of other vinyl monomers that can be copolymerized with the component.
69.4% by weight, and the total of each monomer is
By copolymerizing a monomer mixture of 100% by weight, the glass transition point is -10°C to 40°C, and
A method for producing an acrylic resin for coating with good flexibility, characterized by obtaining a copolymer having a number average molecular weight of 5,000 to 100,000.