JP2861146B2 - Resin composition for paint - Google Patents

Description

The present invention relates to a novel and useful coating resin composition. More specifically, the present invention relates to a specific copolymer centered on a vinyl monomer containing one or more organic phosphate groups in one molecule and an ε-caprolactone-modified monomer, and melamine The present invention relates to a resin composition for coatings containing a resin, and forms a film having excellent flexibility, adhesion, interlayer adhesion, corrosion resistance and the like.

The resin composition for a coating material of the present invention is extremely useful, in particular, as a vehicle for a curable high solid coating material.

[Conventional technology]

In the field of paints, efforts are being made to reduce the amount of solvents used and the amount of volatiles in the atmosphere, and the shift to high solids is a trend, and it is steadily realizing. .

In order to achieve such high solids, it is necessary to reduce the molecular weight of the coating resin itself and also improve the solubility in solvents.

By the way, regarding the improvement of solubility due to the structure of the resin, for the purpose of lowering the glass transition temperature, the polyester or alkyd resin is blended, or the concentration of hydroxyl group, carboxyl group, etc. is adjusted and dissolved. The sex is improved.

Thus, the desired improvement in solubility can be achieved, but on the other hand, on the other hand, with the decrease in the polarity of the resin, the decrease in adhesion to the base material, the decrease in corrosion resistance, etc. become significant The drawback is that, and two,
The drawback that the flexibility is extremely reduced as the molecular weight is reduced also appears.

Considering the existence of these various drawbacks,
As described in U.S. Patent No. 4.546.046, the invention is to add ε-caprolactone to a hydroxyl group in an acrylic resin, and in fact, as the lactone modification rate increases, the flexibility increases. Although an increase in the content itself is observed, an extreme decrease in adhesiveness and a decrease in interlayer adhesion appear.

Under these circumstances, to improve such adhesion, a method of copolymerizing a so-called polar monomer has been widely adopted, but most of them have a short side chain polarity such as acrylic acid or itaconic acid. In the case of using monomers, the solubility is remarkably reduced, so that no definitive solution can be found at present.

[Problems to be solved by the invention]

However, in view of the above-mentioned various disadvantages in the prior art as described above, the present inventors have found that a resin capable of improving properties such as flexibility and adhesion without reducing solubility in solvents. In earnest, he began his research.

Therefore, the problem to be solved by the present invention is, on the one hand, in particular, the usefulness as a vehicle of a curable high solid paint, flexibility, adhesion and corrosion resistance have been significantly improved, and moreover, to an organic solvent. An object of the present invention is to provide a practical resin composition for coatings which does not leave any problem even in the solubility of the resin.

[Means for solving the problem]

The inventors of the present invention have conducted intensive studies with an eye on the problems to be solved by the invention as described above. As a result, a vinyl monomer containing one or more organic phosphate groups in one molecule has been obtained. A resin composition containing a specific copolymer and a melamine resin, which is used in combination with a compound and an ε-caprolactone-modified monomer, has a solubility in an organic solvent that is higher than that of the other, flexibility, and adhesion. , A resin composition capable of forming a film having excellent interlayer adhesion and corrosion resistance, etc., and finding that it is suitable as a resin composition for coatings, particularly, a resin composition for high solids coatings. The invention has been completed.

That is, the present invention relates to a vinyl monomer (a-1) containing one or more organic phosphate groups in one molecule [hereinafter referred to as "organic phosphate group-containing monomers (a-1)". Abbreviated to 0.01 to 5% by weight, and hydroxyalkyl (meth) acrylate partially or entirely modified with ε-caprolactone. And 10 to 60% by weight of the monomer (a-2) containing the ε-caprolactone-modified monomer represented by
(A) a copolymer obtained by copolymerizing 89.99 to 35% by weight of a vinyl monomer (a-3) copolymerizable with -1) and (a-2) as an essential component, preferably The general formula of 0.01 to 5% by weight of the monomers (a-1) and a part or all of 2-hydroxyethyl (meth) acrylate modified with ε-caprolactone And 10 to 60% by weight of the monomer (a-2) containing the ε-caprolactone-modified monomer represented by
A copolymer obtained by copolymerizing 89.99 to 35% by weight of a vinyl monomer (a-3) copolymerizable with -1) and (a-2), more preferably having a glass transition temperature of 30 C. or lower and a low molecular weight copolymer having a number average molecular weight of 5,000 or less, and a melamine resin (B), preferably having 1 carbon atom.
And a melamine resin etherified with a monohydric alcohol represented by formulas (1) to (4).

Here, first, only typical examples of the organic phosphoric ester group-containing monomers (a-1) used in preparing the above-mentioned copolymer (A) will be described. Mono [2- (meth) acryloyloxyethyl] acid phosphate, mono-glycol having a degree of polymerization of polyethylene glycol of 1 to 6 Mono [2- (meth) acryloyloxy polyethylene glycol] acid phosphate, mono-glycol having a polymerization degree of 1 to 6 [ 2- (meth) acryloyloxy polypropylene glycol] acid phosphate or carbon number 1
Mono [2- (meth) acryloyloxyalkyl] acid phosphates further esterified with an alkyl group or a benzyl group.

Then, the organic phosphate group-containing monomers (a-
The amount of 1) used is in the range of 0.01 to 5% by weight,
Preferably, the range of 0.1 to 2% by weight is appropriate.

If it is less than 0.01% by weight, it is not possible to exhibit characteristic effects such as adhesion and corrosion resistance, while if it exceeds 5% by weight, the solubility of the obtained copolymer in organic solvents is inevitable. Is liable to be extremely lowered, and thus, for example, causes a hindrance in designing a high solid content paint, etc., which is not preferable in any case.

The amounts of the monomers (a-2) and the monomers (a-3) to be copolymerized with the monomers (a-1) are as follows. (A-2) is 10-
60% by weight, preferably 15 to 50% by weight, the latter (a-3) being 89.99 to 35% by weight, preferably 8%
It is in the range of 4.9 to 45% by weight.

Next, a monomer (a) containing the above-mentioned ε-caprolactone-modified monomer represented by the general formula [I] in a form in which part or all of the above-mentioned hydroxyalkyl (meth) acrylate is modified with ε-caprolactone. -2) is a monomer in the form of an addition reaction of ε-caprolactone to one or more moles, preferably 1 to 6 moles, of part or all of hydroxyalkyl (meth) acrylate as described later, usually Refers to a mixture of adducts of each mole number, and among them, only the typical ones are exemplified by "Placcel FM or FA series" manufactured by Daicel Chemical Industries, Ltd. and so on.

Examples of the hydroxyalkyl (meth) acrylate used for preparing such monomers (a-2) include:
Examples thereof include (meth) acrylates having an alkylene group having 2 to 4 carbon atoms, such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. 2-Hydroxyethyl (meth) acrylate is preferred.

The amount of the hydroxyalkyl (meth) acrylate used is preferably in the range of 80 to 200 in terms of hydroxyl value.

If it is less than 80, it will be difficult to obtain a sufficiently cured coating film, while if it exceeds 200, the solvent solubility of the obtained copolymer will be extremely reduced, Either case is not preferred.

Further, each of the above-mentioned monomers (a-1) used in preparing the copolymer (A) is used.
And a vinyl monomer copolymerizable with (a-2) (a-
As 3), any one having copolymerizability can be used. Among them, alkyl (meth) having 1 to 22 carbon atoms can be used if only typical ones are exemplified. Acrylates; aromatic vinyl monomers such as styrene, α-methylstyrene, t-butylstyrene or vinyltoluene; 2-ethoxyethyl (meth)
Acrylate, cyclohexyl (meth) acrylate,
Glycidyl (meth) acrylate; (meth) acrylonitrile; mono- or diesters of maleic acid or fumaric acid and a monohydric alcohol having 1 to 18 carbon atoms; N-
(Meth) acrylamides such as alkoxymethyl (meth) acrylamide; N, N-dialkylaminoalkyl (meth) acrylates; or fluorine-containing vinyl monomers such as tetrafluoroethylene or hexafluoropropylene or vinyl acetate .

Unsaturated carboxylic acids such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid and fumaric acid can also be used.

In order to carry out the copolymerization reaction using each of the above-listed monomers, known and commonly used polymerization methods can be applied, and among them, radical solution polymerization is preferable.

In particular, to prepare low molecular weight copolymers, mercaptan compounds such as mercaptoethanol, thioglycerol or lauryl mercaptan; or 2,4
When the reaction is carried out in the presence of a known and conventional chain transfer agent such as -diphenyl-4-methyl-1-pentene or methyl methacrylate dimer, at a high temperature of 140 to 180 ° C, or at a low monomer concentration, The desired copolymer (A) can be easily obtained.

And in the case of the above-mentioned radical solution polymerization,
Solvents such as xylene, "Solvesso" (an aromatic hydrocarbon solvent manufactured by Exxon, Amethica), n-butanol, isobutanol, ethyl acetate, butyl acetate, methyl ethyl ketone or methyl amyl ketone, usually vinyl (co) Those used in the preparation of the polymer are used as they are.

Also, as a radical polymerization initiator, benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, acetylcyclohexane, t-
Butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate, t-amylperoxy-
Usually, various peroxides such as 2-ethylhexanoate or t-amyl peroxybenzoate; or various azo compounds such as azobisisobutyronitrile or azobis (2-methylpropionitrile).
What is used for preparation of a vinyl (co) polymer is used as it is.

Further, ionic polymerization such as anionic polymerization and cationic polymerization can also be easily performed by temporarily protecting the reactive polar group. Therefore, such an ionic polymerization method may be appropriately used.

The copolymer (A) thus obtained has a glass transition temperature of 30 ° C. or less and a number average molecular weight of 5,000 or less, preferably a number average molecular weight in the range of 1,000 to 3,000. The use of one having a molecular weight is particularly desirable.

In the case of a copolymer having a glass transition temperature exceeding 30 ° C.,
Inevitably, the solubility in the solvent tends to be insufficient,
Therefore, for example, it becomes impossible to prepare a high solid content paint, and even in the case of a copolymer exceeding 5,000, such solubility is extremely reduced, and therefore, the object of the present invention can be achieved. Both are not preferred because they are no longer possible.

On the other hand, as the melamine resin (B), it is desirable to use an alkylated melamine / formaldehyde resin.

Such an alkylated melamine / formaldehyde resin generally has an alkyl group having 1 to 4 carbon atoms, and includes methanol, ethanol, n-propanol,
Those prepared by a conventional method of reacting a monohydric alcohol such as isopropanol, n-butanol or isobutanol with a melamine-formaldehyde resin,
That is, it is a melamine resin etherified with a monohydric alcohol.

The melamine resin (B) can be used in any state of a monomer or a polymer. Preferably,
Hexamethoxymelamine, "Cymel 3
00 "[product of Mitsui Cyanamid Co., Ltd.] is a typical commercially available product. Another useful resin is methoxy / butoxy methylmelamine.

And as a usage ratio of the copolymer (A) and the melamine resin (B), the weight ratio of (A) :( B) is 40:60 to 85:
A range of 15 is preferred, preferably a range of 60:40 to 80:20.

〔The invention's effect〕

Thus, the coating resin composition of the present invention containing the copolymer (A) and the melamine resin (B) as a curing agent component has a solid content concentration of 70% by weight or more at the time of coating. The cured coating film obtained by using the composition of the present invention has an extremely high solid content, and is excellent in flexibility, adhesion to metal materials, corrosion resistance, interlayer adhesion, and the like. Therefore, the resin composition for coating of the present invention can be used for line coating of light electric appliances, steel furniture, building materials, and the like, and further, can be used as a top coat for automobiles.

〔Example〕

Next, the present invention by reference examples, examples and comparative examples,
This will be described more specifically. In the following, all parts and percentages are by weight unless otherwise specified.

Reference Example 1 [Preparation Example of Copolymer (A)] A four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube and a dropping funnel was charged with 300 parts of xylene and 40 parts of n-butanol. 130 ° C while introducing nitrogen gas
After that, the raw material mixture as shown below was dropped at a constant speed over a period of 8 hours using a dropping funnel.

Styrene 250 parts 2-Hydroxyethyl methacrylate 200〃 “Placcel FA-1” (1 mol of 2-hydroxyethyl acrylate with an average of 1 mol of ε-caprolactone added thereto) 130〃 Ethyl acrylate 200〃 Methyl acrylate 210〃 Acid Phosphonoxyethyl monomethacrylate 10〃 Mercaptoethanol 40〃 Xylene 38〃 After completion of the dropwise addition, the reaction was continued at the same temperature for 30 minutes to allow the reaction to proceed, and 10 parts of t-butylperoxy-2-ethylhexanoate was added. Was added, and the reaction was continued at the same temperature for 3 hours to obtain a solution of the target copolymer (A). Hereinafter, this solution is abbreviated as copolymer (A-1), and the characteristic values thereof are shown in Table 1.

Reference Example 2 (same as above) A solution (A-2) of the copolymer (A) was obtained in the same manner as in Reference Example 1, except that the composition of the raw material mixture to be dropped was changed as follows.

Styrene 350 parts Methyl methacrylate 60〃 “Placcel FA-2” (1 mol of 2-hydroxyethyl acrylate with an average of 2 mol of ε-caprolactone added thereto) 200〃 2-hydroxyethyl acrylate 160〃 “Phosmer PE” [ Phosphoric acid monomer manufactured by Unichemical Co., Ltd.] 30〕 n-butyl acrylate 200〃 azobisisobutyronitrile 50〃 thioglycerol 30〃 The characteristic values of this copolymer and copolymer solution are as shown in Table 1. It is.

Reference Example 3 (same as above) In the same reaction vessel as Reference Example 1, 2
After charging 20 parts and raising the temperature to 150 ° C. while introducing nitrogen gas, a raw material mixture having the following composition was dropped at a constant speed over 6 hours using a dropping funnel.

Styrene 250 parts Ethyl acrylate 110〃 2-Hydroxyethyl methacrylate 180〃 “Placcel FA-4” (1 mol of 2-hydroxyethyl acrylate with an average of 4 mol of ε-caprolactone added thereto) 360〃 “Phosmer PP” ( 40〃 methacrylic acid 10〃 n-butyl acrylate 50〃 t-amyl peroxy-2-ethylhexanoate 70〃 Sec-phenylethyl alcohol 50〃 30 minutes after the completion of dropping, t-amyl peroxy -2-
10 parts of ethyl hexanote and 50 parts of "Solvesso 100" were dropped at a constant speed for 30 minutes, and the reaction was continued for 4 hours at the same temperature to allow the reaction to proceed. (A-3) was obtained.

The characteristic values of the copolymer and its solution are as shown in Table 1.

Reference Example 4 (same as above) A solution (A-4) of the target copolymer (A) was prepared in the same manner as in Reference Example 3, except that a raw material mixture having the composition shown below was used. Obtained.

Styrene 100 parts n-butyl methacrylate 150〃 lauryl methacrylate 200〃 “Placcel FA-1” (supra) 500〃 acid phosphonooxyethyl monomethacrylate 50〃 t-amyl peroxy-2-ethylhexanoate 80〃 mercaptoethanol The characteristic values of the 50 ° copolymer and its solution are as shown in Table 1.

Reference Example 5 (same as above) In the same reaction vessel as Reference Example 1, 3
Then, 00 parts and 112 parts of butyl cellosolve were charged, the temperature was raised to 135 ° C. under introduction of nitrogen gas, and a raw material mixture having the following composition was dropped by a dropping funnel over 5 hours.

Styrene 200 parts 2-Ethylhexyl methacrylate 300〃 4-Hydroxybutyl acrylate 150〃 “Placcel FA-1” (supra) 120〃 “Placcel FM-1” (1 mol of 2-hydroxyethyl methacrylate has an average of 1 mol of ε- Caprolactone added) 150〃 Acid phosphonooxyethyl monoacrylate 20〃 2,4-Diphenyl-4-methyl-1-penteneethylbenzene 60〃 t-Butylperoxy-2-ethylhexanoate 90〃 Dropping completed Thereafter, the solution was kept at the same temperature for 5 hours to obtain a solution (A-5) of the desired copolymer (A). The characteristic values of this are as shown in Table 1.

Reference Example 6 (Control Copolymer Preparation Agent) A control copolymer solution (A) was prepared in the same manner as in Reference Example 2, except that a raw material mixture having the following composition was used. '-1) was obtained.

Styrene 350 parts 2-Hydroxyethyl acrylate 220 Methyl methacrylate 80 Phosmer PE 30 n-butyl acrylate 320 Asobisisobutyronitrile 50 Thioglycerol 30 Copolymer and its solution It is as shown in Table 1.

Reference Example 7 (same as above) A control copolymer solution (A'-2) was obtained in the same manner as in Reference Example 2, except that the composition of the raw material mixture to be dropped was changed as follows.

Styrene 350 parts Methyl methacrylate 70〃 “Placcel FA-2” (supra) 200〃 2-hydroxyethyl acrylate 150〃 acrylic acid 30〃 n-butyl acrylate 200〃 azobisisobutylnitrile 50〃 thioglycerol 30〃 The characteristic values are as shown in Table 1.

Reference Example 8 (same as above) A control copolymer solution (A'-3) was obtained in the same manner as in Reference Example 2, except that the raw material mixture having the composition shown below was used. .

Styrene 350 parts Methyl methacrylate 80〃 2-Hydroxyethyl acrylate 220〃 N-butyl acrylate 320〃 Acrylic acid 30〃 Azobisisobutyronitrile 50〃 Thioglycerol 30〃 The characteristic values of this compound are as shown in Table 1. It is.

Examples 1 to 5 and Comparative Examples 1 to 3 Various resin compositions were obtained using the respective copolymer solutions obtained in Reference Examples 1 to 8 according to the mixing ratios shown in Table 2. Was.

Next, each of the thus obtained clear paint resin compositions was treated with Ford Cup N using methyl amyl ketone.
It was diluted to 30 seconds at o.4. The non-volatile content at that time was measured, and the result was shown in the same table as "paint non-volatile content".

After that, each clear paint, 0.6m thick
m was coated on a Bonderite # 144 treated steel sheet by air spray so that the dry film thickness became 30 to 35 μm, and then baked at 160 ° C. for 20 minutes.

For each cured coating,
Various performances were evaluated. The results are as shown in the table.

Gloss: Murakami gloss meter (60 ° specular reflection) Hardness: Pencil hardness Exelin: Expressed in “mm” using an Erichsen tester Impact resistance: 500 g test by Dupont tester After cutting to cellophane tape, the number of remaining areas (number of remaining gobangs) was described. Corrosion resistance; After 240 hours of salt spray at 35 ° C,
Peel off with cellophane tape, measure its width and “mm”
1 hour after coating each dye and baking at 170 ° C for 20 minutes, the same paint was repainted and baked at 150 ° C for 20 minutes.
Cut to 0) and peel off the cellophane tape to indicate the number of remaining gobangs Solvent resistance: Use gauze soaked with xylene, load 1.
After rubbing 10 times with 5 kg, determine the purpose of the coating state As is clear from Table 2, the coating resin composition of the present invention is excellent in corrosion resistance, interlayer adhesion, substrate adhesion, and the like, and can significantly increase the non-volatile content of the coating. High solid paint can be used.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C09D 133 / 14,143 / 02 C08L 33/14 C08F 220 / 28,230 / 02,290 / 06

Claims (4)

(57) [Claims] (1) 0.01 to 5% by weight of a vinyl monomer (a-1) containing one or more organic phosphate groups in one molecule.
And a hydroxyalkyl (meth) acrylate obtained by modifying part or all of hydroxyalkyl (meth) acrylate with ε-caprolactone, And 10 to 60% by weight of the monomer (a-2) containing the ε-caprolactone-modified monomer represented by
(A) obtained by copolymerizing 89.99 to 35% by weight of a vinyl monomer (a-3) copolymerizable with -1) and (a-2) as an essential component, and a melamine resin (B). 2. An ε-caprolactone-modified monomer represented by the general formula [I] The resin composition for a paint according to claim 1, which is a monomer represented by the formula: 3. The copolymer (A) has a glass transition temperature of 30 ° C. or lower and a number average molecular weight of 5,000 or lower.
Or the resin composition for coating according to 2. 4. The melamine resin (B) having 1 carbon atom
The resin composition for a paint according to claim 1, 2 or 3, which is a melamine resin etherified with a monohydric alcohol of (4) to (4).