JPH0569128B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a curable resin, and more particularly to a curable resin that is cured by a crosslinking agent and a metal dryer to provide good physical properties of a coating film. [Technical Background and Problems] Conventionally, coatings using resins derived from alkenylphenols have been cured by oxidative polymerization under the catalytic action of a metal dryer or the like. Such paints have excellent properties such as good workability, can be applied thickly, the cured film has high gloss and hardness, and provides an elegant coating surface with excellent durability. However, since the cured coating film is formed only by oxidative polymerization, the internal curing speed is slow, and
Another problem is that an unpleasant odor is generated, which is thought to be caused by low-molecular-weight aldehydes produced as a by-product of oxidation. Therefore, its uses are limited and it is only used in specific industries. [Object of the Invention] The object of the present invention is to provide a curable resin that provides fast curing properties, reduces odor, etc., and has excellent coating film properties without sacrificing any of the advantages of conventional alkenylphenol resin coatings. There is a particular thing. [Summary of the Invention] The present inventors have discovered that these objects can be achieved by introducing an alcoholic hydroxyl group into an alkenylphenol resin and using a crosslinking agent and a metal dryer that are reactive with the hydroxyl group. It came to this. The curable resin of the present invention has the following formula:

[Formula, R ₁ is -CH ₂ -CH ₂ -OH,

[Formula] -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -OH or

[Formula] and may be the same or different. _R2 represents a hydrogen atom or _-OR1 , _R3 represents an unsaturated hydrogen oxide group having 1 to 3 double bonds and having 3 to 17 carbon atoms, and n represents an integer of 3 to 500). It is characterized by having the repeating unit shown. The above-mentioned curable resin of the present invention can be produced, for example, as follows. First, a phenol resin is synthesized by condensing and polymerizing an alkenylphenol with an aldehyde in the presence of an acid or alkali catalyst. Examples of the alkenylphenol include allylphenol, cardanol, urushiol, etc., and in particular, cashew nut shell liquid is preferable from the viewpoint of physical properties, since it is produced in large quantities. Furthermore, phenols such as phenol, cresol, and xylenol can be cocondensed to adjust the hardness of the coating film, but it is necessary to suppress the amount to 50% molar or less in order to delay the curing reaction due to oxidation. The aldehyde used in the condensation polymerization can be selected from formalin, paraformaldehyde, hexamethylenetetramine, and the like. The molar ratio of aldehydes to phenols is 0.5 to 1.2. HCl as a catalyst,
H ₂ SO ₄ , NaOH, ZnCl ₂ and the like are selected from those commonly used in phenolic resin synthesis, and HCl, ZnCl ₂ and the like are excellent for controlling the molecular weight distribution width. Next, the obtained phenolic resin is subjected to an addition reaction with alkylene oxide or alkylene carbonate, if necessary, in the presence of an alkali catalyst such as NaOH, KOH, KaCO ₃ or Na ₂ CO ₃ to alcoholize it, converting the phenolic hydroxyl group into an alcoholic hydroxyl group. This leads to the resin of the present invention. As the alkylene oxide or alkylene carbonate used, ethylene oxide, propylene oxide, ethylene carbonate, and propylene carbonate are preferable from the viewpoint of reactivity. The molar ratio of these compounds to the phenols is desirably 1.0 to 2.0; if it is too low, curing will be insufficient, and if it is too high, it will become too flexible. The molecular weight of the curable resin of the present invention is regulated by the molecular weight of the phenolic resin that is the precursor, but even if the phenolic resin has a low molecular weight, after alcoholization, phthalic anhydride, maleic anhydride, tetrahydrophthalic anhydride, adipine It can be polymerized by esterification with dibasic acids such as acids or by urethanization with isocyanates such as TDI (tolylene diisocyanate). In addition, it can be modified with rosin, linseed oil fatty acid, etc. to improve the physical properties of the coating film or the compatibility with other curing agents. After alcoholization, the remaining catalyst is neutralized and precipitated as an inorganic salt, and unreacted substances are distilled off under reduced pressure, then diluted with a solvent and passed through a hot filter to separate and purify the precipitate. A curable resin solution of the invention is obtained. The resin of the present invention produced in this way undergoes oxidative polymerization using a metal dryer catalyst at the side chain having a double bond, and a crosslinking agent reactive with an alcoholic hydroxyl group, such as an isocyanate resin prepolymer or a urea resin prepolymer. Alternatively, it also has the function of crosslinking with an alcoholic hydroxyl group added to a phenolic hydroxyl group using a melamine resin prepolymer or the like. Thus, unlike conventional alkenylphenol resin paints, it can be cured quickly without relying solely on oxidative polymerization, and has the characteristics of being able to reduce odors and the like caused by oxidative polymerization. In particular, when a metal dryer and an isocyanate resin prepolymer are used in combination, the paint can be cured at room temperature, and the curing time is halved compared to conventional alkenylphenol resin paints. In addition, when a blocked isocyanate resin prepolymer, urea resin prepolymer, or melamine resin prepolymer is used together, it can be made into a one-component product, and although heat curing is required, the coating film has excellent internal curing properties and has high hardness and an excellent appearance. is obtained. Examples of metal dryers used for coating include Co, Pb, Mn, Ca, Zr, Zn, Fe, Al, and
Metals such as Cu and rosin, oleic acid, linoleic acid,
Examples include salts with naphthenic acid, tall oil, etc., which are used alone or in combination. The amount added is 0.01 to 0.1% by weight of metal based on the resin content,
If it is less than 0.01% by weight, curing will be insufficient;
If it exceeds 0.1% by weight, not only will the odor due to oxidative polymerization increase, making it impossible to achieve the object of the present invention, but also the reaction with a crosslinking agent used in combination, such as an isocyanate resin prepolymer, will be excessively accelerated, resulting in poor storage stability.
0.03-0.06% by weight is desirable. Examples of the isocyanate resin prepolymer used as a crosslinking agent include Takenate D102,
Takenate D204, Takenate D110N (trade name, manufactured by Takeda Pharmaceutical Co., Ltd.), Millionate MR, Coronate
Examples of blocking isocyanate resin prepolymers include Takenate B800 (trade name, Takeda Pharmaceutical Co., Ltd.).
(manufactured by) etc. can be used. Examples of urea resin prepolymers include Melan #14 (trade name, manufactured by Hitachi Chemical Co., Ltd.) and Supervecamine D-138-60 (trade name, manufactured by Dainippon Ink Co., Ltd.).
). Furthermore, examples of melamine resin prepolymers include Super Betsukamin J-820 (trade name, manufactured by Dainippon Ink Co., Ltd.) and Tesmin TO-
5160 (trade name, manufactured by Tokushima Oil Co., Ltd.), etc. These crosslinking agents are used in an amount of 10 to 50% by weight based on the resin of the present invention, but if it is less than 10% by weight, it is not very effective.
If it exceeds 50% by weight, the effects of the present invention such as coating film performance cannot be obtained. 20 to 40% by weight is desirable. The present invention will be explained in detail by way of Examples below. Example 1 300 parts by weight of cashew nut shell liquid and 15 parts by weight of hexamethylenetetramine were reacted at 130°C for 2 hours and then at 180°C for 0.5 hours, and 105 parts by weight of ethylene carbonate was added to this in the presence of 0.45 parts by weight of NaOH. 364 parts by weight of a low molecular weight alcoholized resin was obtained. Next, 364 parts by weight of this low molecular weight alcoholized resin and 29.6 parts by weight of phthalic anhydride were subjected to an esterification reaction at 180°C for 8 hours to obtain a resin with an acid value of 6.7. To this resin were added 90 parts by weight of xylene, 30 parts by weight of ethylene glycol monoethyl ether acetate, and 30 parts by weight of butyl acetate to obtain a resin solution with a nonvolatile content of 70%. To 100 parts by weight of this resin solution, 0.2 parts by weight of 12% cobalt octylate and 0.1 part by weight of 6% manganese naphthenate.
A clear varnish was obtained by adding parts by weight and an appropriate amount of leveling agent. Obtained clear varnish
To 100 parts by weight, 30 parts by weight of Takenate D-102 (trade name, manufactured by Takeda Pharmaceutical Co., Ltd.) was added to prepare a paint, which was applied to a glass plate and a mild steel plate, and dried at room temperature. The performance results are shown in Table 1. Example 2 300 parts by weight of cashew nut shell liquid and 81 parts by weight of formalin were mixed in the presence of 0.45 parts by weight of NaOH catalyst.
After holding at 100℃ for 3 hours and dehydrating under reduced pressure,
The reaction was carried out at 180°C for 1 hour, and then for 0.5 hour at 180°C. Add 105 parts by weight of ethylene carbonate to the obtained resin.
React at 160℃ to produce low molecular weight alcoholized resin.
364 parts by weight were obtained. The obtained low molecular weight alcoholized resin was reacted in the same manner as in Example 1, and the same treatment was performed to obtain a clear varnish. This clear varnish was applied to a glass plate and a mild steel plate, and its performance was investigated. The results are shown in Table 1. Example 3 14 parts by weight of tolylene diisocyanate was added dropwise to a mixture of 60 parts by weight of the low molecular weight alcoholized resin obtained in Examples 1 and 2 and 40 parts by weight of xylene, and the mixture was heated at 80°C for 1 hour and then at 100°C for 1 hour. The reaction was carried out to obtain a resin solution with a non-volatile content of 60%. This resin solution was mixed with the same metal dryer and leveling agent as in Example 1, and then applied to a glass plate and a mild steel plate to examine its performance. The results are shown in Table 1. Comparative Example 1000 parts by weight of cashew nut shell liquid and 55 parts by weight of hexamethylenetetramine were reacted at 130°C for 2 hours and then at 180°C for 0.5 hour. To this, 100 parts by weight of xylol, 100 parts by weight of ethyl cellosolve,
Add 100 parts by weight of Sorbetso #100 to remove non-volatile content.
Obtain a 76% resin solution. A clear varnish was obtained by adding 1.0 part by weight of 8% cobalt naphthenate, 0.2 part by weight of 6% manganese naphthenate, and 0.5 part by weight of an anti-skinning agent to 100 parts by weight of this resin solution. This clear varnish was applied to a glass plate and a mild steel plate, and the performance results are shown in Table 1.

【table】

[Table] As is clear from Table 1, the curable resin composition containing the curable resin of the present invention has fast curing properties, has little odor, and has a high quality coating film. It was confirmed that the material had hardness.

Claims (1)

[Claims] 1 The following formula: [Formula] (In the formula, R ₁ may be the same or different for each unit, -CH ₂ -CH ₂ -OH, [Formula] -CH ₂ -CH ₂ -O-CH ₂ -CH ₂ -OH or [Formula], R ₂ represents a hydrogen atom or -OR ₁ , R ₃ is an unsaturated carbon number of 3 to 17 with 1 to 3 double bonds A curable resin having a repeating unit represented by a hydrocarbon group (n represents an integer of 3 to 500).