JPS6023139B2 - Thermosetting acrylic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermosetting acrylic resin composition, more specifically,
The present invention relates to a thermosetting acrylic resin composition characterized in that a powdered acrylic resin having at least one of a carboxyl group and a hydroxyl group introduced into its molecules is dispersed in a liquid dispersant as a stable system.

Conventionally, dispersed compositions have been produced in which powdered vinyl chloride resin is dispersed in a plasticizer (e.g., di-2-ethylhexyl phthalate and tricresyl phosphate) or a solvent with a low ability to dissolve the resin (e.g., a chain hydrocarbon solvent). are widely used as plastisols and organosols, coating materials for paints, etc., and molding compounds.

However, since such compositions have poor adhesion to substrates, when they are used as paints, they require an undercoat that acts as an adhesive. In addition, the coating film formed from the composition may become sticky when heated due to its thermoplastic nature and the influence of the plasticizer, or may swell or melt due to organic solvents, or the plasticizer may dissolve and its physical properties may deteriorate. There were problems such as deterioration of the film, decrease in film resistance, and discoloration. On the other hand, there are many solid resins used as paint resins, such as alkyd resins, acrylic resins, epoxy resins, and polyester resins, but all of these resins can be dissolved in a solvent and used as solution-based paints. It is used as a powder coating or as a powder coating.

Furthermore, when these coating resins have low molecular weights, they easily swell or dissolve in plasticizers or solvents, but when they have high molecular weights, they tend not to swell or dissolve in such agents, and they also tend to deteriorate fluidity during film formation. It was something to do. Therefore, it has been considered difficult to obtain a dispersion type paint with good paint properties and film performance from such resins. As a result of intensive research to solve these problems, the present inventor focused on the molecular weight of the acrylic resin and the polarity of the resin due to the introduction of carboxyl groups and hydroxyl groups, and by specifying both, The present inventors have discovered that the resin can be maintained in powder form as a stable system in a liquid dispersant, and have completed the present invention.

The gist of the present invention is to provide a compound having a number average molecular weight of 3000 to 1 containing at least one of a carboxyl group and a hydroxyl group.
0000 powdered acrylic resin and a liquid dispersant selected from the group of epoxy compounds, melamine compounds, imide compounds, and compounds having polymerizable double bonds, the content of such groups in the resin is , 4 to 2% by weight in the case of a carboxyl group alone, 2 to 6% by weight in the case of a hydroxyl group alone, and 2.7 to 14% in the case of a combination of a carboxyl group and a hydroxyl group. $wt% and 2.2
5.1% by weight of the thermosetting acrylic resin composition.

The powdered acrylic resin used in the present invention has a number average molecular weight of 3000 to 1000, preferably 4000 to 6.
000 and contains at least one type of carboxyl group and hydroxyl group, and the content of such group in the resin is [1' carboxyl group alone, 4 to 2% by weight]
, [2} 2 to 6% by weight in the case of a hydroxyl group alone, and 2.7 to 14.9% by weight and 2.2 to 5.1% by weight in the case of a combination of a carboxyl group and a hydroxyl group, respectively; Such acrylic resin can be manufactured using conventional raw materials and methods.

For example, carboxyl group-containing polymerizable monomers (e.g. methacrylic acid) and/or hydroxyl group-containing polymerizable monomers (e.g. 2-hydroxyethyl methacrylate) and other polymerizable monomers (e.g. methyl methacrylate,
n-butyl acrylate, isobutyl methacrylate, and styrene) are blended in a predetermined ratio and reacted as appropriate by conventional polymerization methods, such as emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization, until the desired number average molecular weight is obtained. That's fine. In particular, suspension polymerization is the simplest and most advantageous.
When the above number average molecular weight is less than 300 degrees, the particle stability of the acrylic resin in the dispersant decreases and it becomes easy to dissolve.
The viscosity of the composition of the present invention increases and the workability decreases.
If it exceeds 000, the particle stability of the acrylic resin in the dispersant is good, but it melts during heating and hardening.
This makes it difficult to obtain a smooth painted surface. If the content of the above-mentioned functional groups is less than the respective ranges, the acrylic resin particles will easily dissolve in the dispersant, the viscosity of the composition of the present invention will increase, the workability will decrease, and (over time) the color will change. On the other hand, if the stability is likely to be poor, if the respective ranges are exceeded, the dispersion stability will not be good, and the firmness of the composition of the present invention will be poor, and this will cause the expected performance of the coating to deteriorate. This results in poor bending resistance, impact resistance, adhesion, and chemical resistance. From the viewpoint of dispersion stability, it is desirable that the powder particle size of the acrylic resin has a distribution of 1 to 100 mm, preferably 4 to 70 mm, with a maximum value around 20 mm. There are no particular restrictions on the grinding process, and a normal jet mill,
It may be carried out in a pulverizer such as a hammer mill, a heather mill, a Victory mill, or a turbo mill. The above-mentioned adjustment of the powder particle size is achieved by passing the powder through a ring with a predetermined mesh after crushing. The desired thermosetting acrylic resin composition can be obtained by dispersing the powdered acrylic resin into which at least one of a carboxyl group and a hydroxyl group, which is obtained as described above, is introduced into a liquid dispersant. The liquid dispersants used are classified as follows. [a] Liquid dispersants that crosslink with the acrylic resin, specifically, polymerizable unsaturated epoxy compounds (such as glycidyl methacrylate and allyl glycidyl ether) ), polyfunctional epoxy compounds (for example, diglycidyl ether of bisphenol A and ethylene glycoyl diglycidyl ether).

Examples of dispersants having a functional group that reacts with hydroxyl groups include melamine compounds (e.g., hexamethoxymethylmelamine), imide compounds (e.g., 1,1-dimethyl-
1-(2-hydroxybropyl)amine methacrylimide) and the like. Such a liquid dispersant is used in such a proportion that its functional groups are in an equivalent ratio of 0.5 to 1.5 to the carboxyl groups and hydroxyl groups of the acrylic resin. If the ratio is outside this range, the performance of the resulting cured coating film tends to deteriorate. These liquid dispersants may be used alone or in a mixture of two or more, and may be used with ordinary peroxide catalysts (e.g. t-butyl peroxybenzoate, di-t-butyl peroxybenzoate,
-butyl/guoxide and penzoyl peroxide) from 0.1 to 1% by weight, preferably 0% by weight, based on the dispersant.
．． It is desirable to add it in a range of 5 to 5% by weight. {b
- A liquid dispersant that does not crosslink with the acrylic resin but has a polymerizable double bond, such as 1,10-decanediol dimethacrylate, trimethylolethane triacrylate, t-butylstyrene, triallyl trimertate, triallyl isocyanurate , diallyl phthalate, dioctyl itaconate and dibutyl itaconate.

Such liquid dispersants may be used alone or in combination of two or more in an amount of 30 to 15 parts by weight based on 10 parts by weight of the acrylic resin. If it is less than this range, the fluidity characteristics of the composition of the present invention will deteriorate, and if it exceeds this range, the properties of the acrylic resin will not be reflected in the cured coating film. In the case of this liquid dispersant, it is desirable to add a normal peroxide catalyst as in the case of the dispersant 'a} above. 'c) Above [a and 'b
} Examples include di-2-ethylhexyl phthalate and tricresyl phosphate.

In the case of such a liquid dispersant, as in the case of the above-mentioned dispersant 'b), 30 to 1
It is desirable to use 5 parts by weight. The above-mentioned dispersants [phantom, [bl] and [c] used in the present invention may be used alone or may be used in an appropriate combination. c} for {
a} and/or 'b}.

In addition to the dispersant, a solvent that does not dissolve the acrylic resin (for example, n-hexane, mineral spirit, and naphtha) may be used if necessary. Furthermore, coloring pigments, extender pigments, and other fillers commonly used in the field may be blended in appropriate proportions. The dispersion method for the composition of the present invention can be carried out in accordance with a conventional method. For example, when preparing a colored paint containing a pigment, first mix the pigment and the above-mentioned dispersant, add a filler if necessary, and use a pot mill, a three-funnel mill, etc. Dispersion is performed using a ball mill or the like to obtain a liquid color toner.

Next, the powdered acrylic resin is added to this toner, and the toner is uniformly and sufficiently dispersed using a pot mill, double arm kneader, turbine mixer, boat mill, roll mill, etc. The prepared composition of the present invention may be used as it is, or if necessary, it may be subjected to deaeration treatment in a deaerator before use. In order to cure the composition of the present invention, although it varies depending on the type of dispersant and the melting temperature of the acrylic resin, it is usually 120 to
Baking temperatures of 190°C, preferably 140-160°C are suitable.

The composition of the present invention thus formed has good dispersion stability and fluidity during film formation, and since it has carboxyl groups and/or hydroxyl groups in the acrylic resin, it has good dispersibility when reacting with such groups. When used, it is possible to carry out an advantageous thermal crosslinking reaction, resulting in the formation of a coating film with physical and chemical properties that cannot be obtained with conventional plastisols and organosols, and has particularly excellent adhesion. The need for priming is eliminated.

Therefore, it can be said that the composition of the present invention can be widely used as a coating material for forming various cured coating films, and is economically advantageous. Next, the present invention will be specifically explained with reference to Examples and Comparative Examples.

In the Examples and Comparative Examples, "parts" and "%" mean "parts by weight" and "% by weight." Example 1 As a powdered acrylic resin, 15 parts of methacrylic acid, 4 parts of methyl methacrylate, 15 parts of styrene, 1 part of n-butyl methacrylate, 1 part of n-butyl acrylate, and 10 parts of isobutyl methacrylate were copolymerized. The obtained number average molecular weight is 4900 and the carboxyl group content is 7.
．． Grind 1% acrylic resin with a hammer mill to 15%
Use one passed through a 0 mesh section.

7 parts of titanium oxide are added to 75 parts of 1,10-decanediol methacrylate and 25 parts of glycidyl methacrylate and dispersed in a pot mill to obtain a color toner.

To this was added 100 parts of the powdered acrylic resin, dispersed in a pot mill for 1 hour, and then 2.7 parts of t-butyl peroxybenzoate was added to prepare a thermosetting acrylic resin composition. The above composition is applied to a 0.8-thick willow degreased steel plate with a doctor plate to a film thickness of 70 to 120 mm, and then baked in a baking oven at 160° C. for 30 minutes to form a coating film.

The dispersion stability and coating performance results of the above compositions are shown in Table 1. Example 2 Number average molecular weight obtained by copolymerizing 33 parts of 2-hydroxyethyl methacrylate, 3 parts of methyl methacrylate, 16 parts of styrene, 10 parts of n-butyl acrylate, and 9 parts of isobutyl methacrylate as a powdered acrylic resin. An acrylic resin having a hydroxyl group content of 4800 and a hydroxyl group content of 3.6% and treated in the same manner as in Example 1 is used.

75 parts of 1,10-decanediol dimethacrylate and 25 parts of hexamethoxymethyl melamine (Nippon Gosei Kagaku brand name "Nikalak MX-10L") were added with 7 parts of titanium oxide, and a color toner was prepared in the same manner as in Example 1. obtain.

To this was added 10 parts of the powdered acrylic resin, and after dispersing in a pot mill for 1 hour, 1.8 parts of t-butyl peroxybenzoate was added to prepare a thermosetting acrylic resin composition. Table 1 shows the dispersion stability of the above composition and the performance results of the coating film formed under the same conditions as in Example 1. Example 3 As a powdered acrylic resin, 10 parts of methacrylic acid, 22 parts of 2-hydroxyethyl methacrylate, 2 $ parts of methyl methacrylate, 15 parts of styrene, 1 $ part of 2-butyl acrylate, and 14 parts of isobutyl methacrylate
with a number average molecular weight of 4800, a carboxyl group content of 4.7% and a hydroxyl group content of 2.
．． A 5% acrylic resin treated in the same manner as in Example 1 is used.

30 parts of 1,10-decanediol dimethacrylate,
7 parts of titanium oxide is added to 38.5 parts of triallysocyanurate, 15 parts of hexamethoxymethyl melamine used in Example 1, and 16.5 parts of glycidyl methacrylate, and a color toner is obtained in the same manner as in Example 1. .

To this, 10 parts of the above-mentioned powdered acrylic resin were added, and after dispersing in a pot mill for 1 hour, 2.3 parts of t-butyl peroxybenzoate was added to prepare a thermosetting acrylic resin composition. Table 1 shows the dispersion stability of the above composition and the performance results of the coating film formed under the same conditions as in Example 1. Example 4 7 parts of titanium oxide were added to 68.5 parts of di-2-ethylhexyl phthalate, 15 parts of hexamethoxymethylmelamine used in Example 1, and 16.5 parts of glycidyl methacrylate, and the same procedure as in Example 1 was carried out. Get a color toner.

To this was added 10 parts of the powdered acrylic resin used in Example 3, dispersed in a pot mill for 15 hours, and then 0.7 parts of t-butyl peroxybenzoate was added to prepare a thermosetting acrylic resin composition. The dispersion stability of the above composition and the performance results of the coating film formed under the same conditions as in Example 1 were evaluated as follows.
Shown in the table.

Comparative Example 1 One part of di-2-ethylhexyl adipate and one part of titanium oxide were dispersed in a three-roll mill to obtain a color toner.

To this, 7 parts of di-2-ethylhexyl adipate, vinyl chloride resin (trade name "Zeon 121" manufactured by Nippon Zeon Co., Ltd.)
10 parts and 2 parts of a vinyl chloride resin stabilizer (trade name: "Advustab T-17MJ" manufactured by Katsuta Chemical Industries, Ltd.),
A vinyl chloride resin composition is prepared by dispersing in a double arm kneader for 2 hours and then defoaming under reduced pressure. Table 1 shows the performance results of the coating film formed under the same conditions as in Example 1 except that the dispersion stabilizer of the above composition and the baking conditions were changed to 190:00 for 1 minute.

Table 1 Note ■ (Viscosity of composition stored at 2500 for 1 month) / (
The ratio of viscosity of the composition immediately after adjustment is determined.

○: Good (the ratio≦1.2), ×: Poor (the ratio>1.
2). Note that in each example, a composition containing no t-butylperoxybenzoate was observed. ■
According to JIS-K-5400-6-14. ■ Use a knife to cut 100 goblets in the two skins, then perform a pressure peel test using adhesive tape to observe the peeling state. ○: Good (number of goblets remaining in the coating film≧80/100), ×: poor (number of goblin marks remaining in the paint film<80/100). ■ JIS-K-
Based on 5400-6-16-1, the situation was judged when 900 bends were made.

○: Good (no coating film cracks), ×: Poor (coating film cracks occurring). ■ JIS-K-5400-6-1
According to method B in 3-3.

○: Good (no cracking or peeling of the paint film at a bell height of 50 skin), ×: Poor (no cracking or peeling of the paint film at a bell height of 30 skin,
(Peeling may occur). ■ Determine the state of traces after staining with marker ink and wiping it with a methanol-impregnated cloth after leaving it at 20°C for 24 hours.

○: Good (no traces), x: Poor (with traces). Example 5 A color toner is obtained in the same manner as in Example 1 by adding 5 parts of glycidyl methacrylate, 5 parts of hexamethoxymethyl melamine used in Example 1, and 7 parts of titanium oxide.

To this is added 10 parts of the powdered acrylic resin used in Example 3, dispersed into one vowel in a pot mill, and then 3.6 parts of t-butyl peroxybenzoate is added to prepare a thermosetting acrylic resin composition. . The dispersion stability of the above composition and the performance results of the coating strength formed under the same conditions as in Example 1 were evaluated in the second test.
Shown in the table.

Example 6 A color toner is obtained in the same manner as in Example 1 by adding 7 parts of titanium oxide to 100 parts of 1.10-decanediol dimethacrylate.

To this, 10 pieces of the powdered acrylic resin used in Example 3 were added, and after dispersing in a pot mill for one morning, 2.4 parts of t-butyl peroxybenzoate was added to prepare a thermosetting acrylic resin composition. do. The dispersion stability of the above composition and the performance results of the coating film formed under the same conditions as in Example 1 were evaluated in the second example.
Shown in the table.

Example 71 10-decanediol methacrylate 7
A color toner was obtained in the same manner as in Example 1 by adding 7$ of titanium oxide to 5 parts and 25 parts of di-2-ethylhexyl phthalate.

To this was added 10 parts of the powdered acrylic resin used in Example 3, and after dispersing in a pot mill for 15 hours, 1.8 parts of t-butyl peroxybenzoate was added to prepare a thermosetting acrylic resin composition. do. Dispersion stability of the above composition,
Table 2 shows the performance results of the coating film formed under the same conditions as in Example 1.

Table 2 Comparative Examples 2 to 9 Acrylic resins having the monomer composition and characteristics shown in Table 3 and treated in the same manner as in Example 1 were used as powdered acrylic resins.

7 parts of titanium oxide was added to 30 parts of 1,10-decanediol dimethacrylate, 38.5 parts of triallylysocyanurate, 15 parts of hexamethoxymethylmelamine used in Example 1, and 16.5 parts of glycidyl methacrylate, A color toner is obtained in the same manner as in Example 1.

To this was added 10 Yuito of the above powdered acrylic resin, and after immediately dispersing it in a pot mill, 2.3 parts of t-butyl peroxybenzoate was added to prepare a thermosetting acrylic resin composition. Table 3 shows the dispersion stability of the above composition and the performance results of the coating film formed under the same conditions as in Example 1.

Table 3 Example 8 As powdered acrylic resin, 10 parts of methacrylic acid, 2-
A product obtained by copolymerizing 22 parts of hydroxyethyl methacrylate, 2 parts of methyl methacrylate, 15 parts of styrene, 1 part of n-butyl acrylate, and 14 parts of isobutyl methacrylate with a number average molecular weight of 4800 and a carboxyl group content of 5.2 % and hydroxyl group content 2.9%
An acrylic resin treated in the same manner as in Example 1 is used.

Epoxy resin (product name: “Epicoat 82” manufactured by Shiel Kagaku Co., Ltd.)
A color toner is obtained in the same manner as in Example 1 by adding 7 anchor parts and 7 base parts of sea bream titanium oxide of hexamethoxymethylmelamine 3 used in Example 1.

100 parts of the above powdered acrylic resin was added thereto, dispersed in a pot mill for 1 hour, and then 0.1 part of tetramethylammonium chloride was added to prepare a thermosetting acrylic resin composition. Dispersion stability of the above composition and Example 1
Table 4 shows the performance results of coating films formed under the same conditions. Example 91 10-decanediol methacrylate 75
7 parts of titanium oxide were added to 25 parts of the epoxy resin used in Example 8, and a color tone was prepared in the same manner as in Example 1.
get a ner.

To this was added 10 parts of the powdered acrylic resin used in Example 8, and the mixture was dispersed in a pot mill for 15 hours, followed by 2.5 parts of t-butyl peroxybenzoate and 0.05 part of tetramethylammonium chloride. to prepare a thermosetting acrylic resin composition. Table 4 shows the dispersion stability of the silk composition and the performance results of the coating film formed under the same conditions as in Example 1.

Comparative Example 10 Powdered acrylic resin obtained by copolymerizing 40 parts of methacrylic acid, 15 parts of methyl methacrylate, 15 parts of styrene, 1 part of n-butyl acrylate, 1 part of isobutyl methacrylate, and 10 parts of n-butyl methacrylate. An acrylic resin having a number average molecular weight of 2800 and a carboxyl group content of 20.9% was treated in the same manner as in Example 1.

A thermosetting acrylic resin composition is prepared in the same manner as in Example 9 using 100 parts of powdered acrylic resin.

Table 4 shows the dispersion stability of the above composition and the performance results of the coating film formed under the same conditions as in Example 1.

Comparative Example 11 As a powdered acrylic resin, an acrylic resin having a number average molecular weight of 12,100 and a carboxyl group content of 20.9% obtained by copolymerizing the same monomer composition as in Comparative Example 10 was used as in Example 1. Use the processed one.

A thermosetting acrylic resin composition is prepared in the same manner as in Example 9 using 10 parts of the above powdered acrylic resin.

Table 4 shows the dispersion stability of the above composition and the performance results of the coating film formed under the same conditions as in Example 1.

Comparative Example 12 5 parts of methacrylic acid, 12 parts of 2-hydroxyethyl methacrylate and 8 parts of n-butyl acrylate
The acrylic resin obtained by copolymerizing 3 parts of monomer composition is 100% solids, exhibits a liquid state with a bubble viscosity of Z to O, has a number average molecular weight of 1650, a carboxyl group content of 2.6%, and a hydroxyl group content. The rate is 1.6%.

A thermosetting acrylic resin composition is prepared in the same manner as in Example 9 using the above liquid acrylic resin. Table 4 shows the performance results of a coating film formed from the above composition under the same conditions as in Example 1.

Note that the dispersion stability of the composition was not evaluated because the acrylic resin is liquid and completely compatible with the color toner. Table 4 Method■ By visual judgment.

Claims (1)

[Claims] 1. A liquid dispersion selected from the group of a powdered acrylic resin containing at least one carboxyl group and a hydroxyl group and having a number average molecular weight of 3,000 to 10,000, and an epoxy compound, a melamine compound, an imide compound, and a compound having a polymerizable double bond. The content of such groups in the resin is 4 to 20% by weight in the case of a carboxyl group alone, 2 to 6% by weight in the case of a hydroxyl group alone, and a dispersion consisting of a carboxyl group and a hydroxyl group. A thermosetting acrylic resin composition characterized in that the amounts are 2.7 to 14.9% by weight and 2.2 to 5.1% by weight, respectively.