JPS62101667A - Thermosetting coating composition - Google Patents

Abstract

PURPOSE:To provide a thermosetting coating compsn. which gives a coating film having excellent resistance to acids, gasoline and water, durability, etc. and is suitable for use in coating plastic substrates, etc., containing an alkyd resin having specified properties, a polyol resin and an amino resin. CONSTITUTION:An alkyd resin having a hydroxyl value of 50-140 and contg. at least one member selected from aliph. bivalent alcohols of formula I (wherein n is 4-10) (e.g., 1,4-butylene glycol), aliph. dibasic acids of formula II (e.g., adipic acid) and lactones of formula III (e.g., delta-valerolactone) is prepd. 100pts.wt. said alkyd resin is mixed with 5-100pts.wt. polyol composed of polycaprolactone having a number-average MW of 4,000-100,000, an amino resin and a solvent (e.g., toluene) to obtain the desired thermosetting coating compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermosetting coating composition comprising a specific alkyd resin, a specific polyol resin, and an amino resin, and is particularly suitable for coating plastic substrates. The present invention relates to curable coating compositions.

[Conventional technology]

In recent years, as synthetic resins have progressed and their applications have been developed, plastic materials such as polyurethane resins, polycarbonates, nylon resins, ABS resins, and polyester resins are replacing metal materials.

In particular, in the automobile industry, replacing conventional steel plates with plastic materials makes it possible to make the car body more noisy and absorb impact energy, and since rust does not occur, the conversion to plastic materials is actively promoted. It is being Along with this, there is a demand for paints suitable for coating plastic materials.

JP-A-58-111864 discloses a coating composition for flexible substrates comprising an oil-free polyester resin and an aminoaldehyde resin.

In this coating composition, methylene long chain bonds are introduced as a component that increases the intramolecular plasticizing effect of the resin, and furthermore, in order to impart good coating film appearance, water resistance, chemical resistance, etc. without impairing elasticity. A polyester resin with a low hydroxyl value into which an alicyclic polybasic acid has been introduced and an aminoaldehyde resin are used together.

[While the invention is trying to solve the problem]

The coating composition comprising an oil-free polyester resin and an aminoaldehyde resin disclosed in the above publication has a -2
The physical properties of the coating film at low temperatures of 0 to -30C are good, but the hardness, blocking properties, and gasoline resistance (staining and softening) are insufficient, making it a coating for automotive plastic substrates that requires durability. There are practical problems as a material.

The present invention solves the above problems and provides a thermosetting coating composition that produces a coating film with excellent blocking properties, hardness, gasoline resistance, acid resistance, water resistance, weather resistance, etc. and excellent durability. The purpose is to

[Failure to solve the problem]

The present invention provides a thermosetting coating resin composition containing an alkyd resin, a polyol resin, and an amino resin,
The alkyd resin has a hydroxyl value of 50 to 140, and its components include the general formula (I) % formula % () (in the formula, n indicates the number of repetitions of 1,000 CH2+, and 4 to 10 an aliphatic dihydric alcohol represented by the general formula (II) (which is an integer of
CH2) (ID (wherein, n is the same as above) and aliphatic dibasic acid and general formula (III) (wherein, n is the same as above) The polyol resin has at least one type of lactone in an amount of 5 to 50% by weight, the polyol resin is a polyrolactone having a number average molecular weight of 4,000 to 100,000, and the polycalolactone is the alkylated resin. 100
It relates to a thermosetting coating composition which is blended in an amount of 5 to 100 parts by weight.

The alkyd resin in the present invention contains at least one of the compounds represented by the above general formulas (I) to (III) as a component, and may also be reacted with other polyhydric alcohols and/or polybasic acids as appropriate. are synthesized.

Examples of the resin group dihydric alcohol represented by the general formula (I) include 1,4-butylene glycol, 1,5-bentanediol, 1,6-hexanediol, 1,7-hebutanediol, and 1,8-octane. There are diols, 1,9-nonanediol, 1,10-decanediol, etc., and these can be used alone or in combination of two or more.

Other polyhydric alcohols include, in addition to the aliphatic dihydric alcohols mentioned above, polyhydric alcohols commonly used in the production of alkyd resins, such as ethylene glycol, frepylene glycol, diethylene glycol, dipropylene glycol, and triethylene glycol. Glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3
-Butylene glycol, neopentyl glycol, 2゜5-hexanediol, esterified product of hydroxyhybalic acid toneopentyl glycol, 2,2゜4-trimethyl-1,3-bentanediol, tricyclodecane dimetatool, 1,4 -Cyclohexane dimetatool, dimethylolpropionic acid, trimethylolethane, trimethylolpropane, RiIJ serine, tris(2-hydroxyethyl)in cyanurate, hentaerythritol, diglycerin, dipentaerythritol, norbit, trishydroxy One or more types of methylaminoester, tan, etc. can be used. Glycidyl esters of branched synthetic fatty acids (for example, Cardura-E manufactured by Shell Chemical Co., Ltd.), long-chain alkylene monoevokinds (for example, ADE manufactured by Daicel Corporation), etc. can be similarly utilized as polyhydric alcohols.

An example of an aliphatic dibasic acid represented by the general formula (ID is 1
For example, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, nonane-1,9-dicarboxylic acid,
Examples include decane-1,10-dicarboxylic acid, and these can be used alone or in combination of two or more.

Other polybasic acids include, in addition to the aliphatic dibasic acids mentioned above, polybasic acids commonly used in the production of alkyd resins, such as phthalic acid, isophthalic acid, terephthalic acid, dimethyl terephthalate, tetrahydrophthalic acid, and hexahydrophthalic acid. Phthalic acid, maleic acid, toIJmellitic acid, hymic acid or acid anhydrides thereof can be used. In addition, a small amount of benzoic acid, p -tert-
It can be used in place of butylbenzoic acid and vegetable oil fatty acids. From the viewpoint of coating film properties such as gasoline resistance and blocking properties, aromatic polybasic acids such as inphthalic acid, phthalic acid, and terephthalic acid are preferred.

As the lactone represented by general formula (III), δ-
Examples include valerolactone and ε-caprolactone.

The compounds represented by general formulas (I) to (ID) are used in an alkyd resin in a total amount of 5 to 50% by weight.If the amount is less than 5% by weight, the durability of the coating film tends to decrease. If it exceeds 50 weight quantum, the hardness, gasoline resistance, and blocking properties of the film tend to decrease.The weight percent here refers to the above general formula (
It is the ratio of the total amount of compounds represented by I) to (II[).

Furthermore, the alkyd resin of the present invention has a hydroxyl value of 50 to 14.
0. When the hydroxyl value is less than 50, the curability becomes insufficient and the gasoline resistance of the coating film tends to decrease, and when it exceeds 140, the elasticity of the coating film tends to decrease. The hydroxyl value of the alkyd resin can be adjusted by adjusting the composition of the raw materials used during its production.

The alkyd resin of the present invention can be manufactured by a method similar to the method for manufacturing ordinary alkyd resins.

For example, the raw materials are heated in a reaction vessel at a temperature of 190 to 250 C, and the condensation polymerization is proceeded without allowing the water produced to distill out of the system. When the appropriate viscosity and acid value are reached, the reaction is terminated and the desired alkyd resin is produced. get.

The polycaprolactone used in the present invention has a number average molecular weight of 4,000 to 100,000, such as Plaxel 240 (number average molecular weight 1-4000), Plaxel H-1
(number average molecular weight, 10,000), Plaxel H-4 (number average molecular weight, 40,000 to 60,000), Plaxel H-7 (number average molecular weight, 7 to 60,000)
100,000) etc. from Daicel Chemical Industries, Ltd.

Polycaprolactone is blended in an amount of 5 to 100 parts by weight, preferably 5 to 100 parts by weight, based on 100 parts by weight of the alkyd resin.
If the amount is less than 50 parts by weight, no effect will be observed, and if it exceeds 100 parts by weight, the gloss will decrease. High molecular weight polycaprolactone has physical properties such as high crystallinity and high elongation, so it provides elasticity to the coating film without reducing hardness, blocking properties, or gasoline resistance. For this reason, the number average molecular weight is 4,000 to 1.
00.000 is used.

In the thermosetting coating composition according to the present invention, the amine resin used in combination with the alkyd resin and polycaprolactone is produced by reacting melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, etc. with an aldehyde.

As the aldehyde, formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, etc. are used. Among these, the amine resin may be modified with alcohol such as methyl alcohol, ethyl alcohol, 0-butyl alcohol, and isophthyl alcohol.

Since plastic materials are easily deformed by heat, it is preferable to bake the paint at a low temperature, and in terms of the appearance of the paint film, it is necessary to obtain a smooth paint film without repelling. In consideration of these points, n-butyl alcohol-modified melamine resin, which has good low-temperature curability, is preferred.

The ratio of the total amount of alkyd resin and polycaprolactone to the solid content of amino resin in the thermosetting coating composition according to the present invention is preferably 85/15 to 70/30 (weight ratio).

If desired, a blocked isocyanate can be used for less than 50 weight quantum of the amine resin.

As the block polyisocyanate, inphorone diisocyanate-1'+1. Phenol polyisocyanates such as 6-hexamethylene diisocyanate and tolylene diisonanate.

This is blocked with ethyl acetoacetate or the like.

For example, DC2753 (product name of Nippon Polyurethane Co., Ltd.)
It is commercially available as Takenate B815N (trade name of Shikinichi Yakuhin Co., Ltd.).

Solvents that can be used in the thermosetting coating composition according to the present invention include:
Same as normal amine resin/alkyd resin composition,
For example, aromatic solvents such as xylene and toluene, ketones such as methyl ethyl ketone and methyl isobutyl ketone, esters such as n-butyl acetate and ethyl acetate, alcohols such as methanol and n-butanol, ethyl cellosolve, butyl cellosolve, and cellosolve acetate. cellosolve series such as, carpitol series such as ethyl calpitol, butyl calpitol, carpitol acetate, heptane,
One or more types of saturated hydrocarbons such as cyclohexane, petroleum solvents, mineral spirits, etc. can be used.

The thermosetting coating composition according to the present invention can be made into a paint by blending a common pigment with a common pigment dispersion method, if necessary. It also contains various additives such as plasticizers, coating-strengthening resins, dispersants, coating surface conditioners, fluidity conditioners, ultraviolet absorbers, ultraviolet stabilizers, antioxidants, and crosslinking reaction accelerators. Good too.

The coating composition of the present invention can be coated by conventional coating methods. For painting,
Air spray machines, airless spray machines, electrostatic coating machines, dip coating machines, roll coating machines, etc. can be used.

The thermosetting coating composition according to the present invention needs to be crosslinked and cured by heating, and generally at 90 to 180C.
Heat for ~100 minutes. Appropriate heating temperature and time should be determined by considering the heat deformation temperature of the base material.

Select as appropriate.

〔Example〕

Next, the present invention will be described in detail based on Examples, but the present invention is not limited thereto.

Hereinafter, parts mean parts by weight.

Example 1 (I) Cardura-E (Shell Chemical 5.0 parts, Neobetathil 20.2 parts of glycol, 1°6 hexanediol 10.
0 parts, trimethylolpropane 15.7 parts, isophthalic acid 57.0 parts, and adipic acid 5.0 parts and heated.

The reaction temperature is gradually raised to 220C, and condensed water is removed from the system through a rectification column. When the temperature of the rectification column falls below 80C, xylene is added to the reaction tank.

The reaction is continued by the solvent reflux method. When the acid value of the contents of the reactor reaches 12, the reaction is terminated and the reactor is cooled.

Alkyd resin A having a hydroxyl value of 112 was obtained. (The hydroxyl value is measured by an acetylation method using acetic anhydride and pyridine, and is expressed as the number of mg of potassium hydroxyl having the same mole as the hydroxyl group contained in 1 g of resin.) Plaxel H -4 Polycaprolactone, number average molecular weight 40,000 to 60,000; Daicel Chemical Industries, Ltd. trade name) 15
Parts by weight were blended.

(2) Using the above formulation, a white enamel paint was prepared by dispersing the pigment using a paint shaker according to the following formulation.

The above mixture 75 parts Titanium white 100 parts Xylene 50 parts Butyl cellosolve 20 parts Total 295 parts The above white enamel paint was mixed with Kinlen/Butyl cellosolve/
It was diluted with a mixed solvent of n-butanol=80/10/10 (weight ratio) to a viscosity of 20 sec (Ford cup≠4.25 c).

(3) Degrease a R, -R, IM polyurethane plate with a test thickness of 3fi with trichloroethane, apply a one-component polyurethane primer on it so that the dry film thickness is 8μ, and apply 80C x 2
After drying for 0 minutes, this was used as a base material. The diluted enamels produced in the above Examples and Comparative Examples were air-sprayed onto this base material so that the dry film thickness became 25 to 30 μm, and the enamels were baked for 12 (I'X2'O) and completely baked and dried. Table 1 shows the results of testing the properties of the coated film samples.

Example 2 Using the same equipment as in Example 1, neopentyl glycol 3
8.4 parts of trimethylolpropane, 10.2 parts of inophthalic acid, and tO,O parts of adipic acid were charged and heated. The reaction temperature is gradually raised to 220C, and condensed water is removed from the system through a rectification column. The temperature of the rectification column is 80C
When the amount is below, xylene is added to the reaction tank and the reaction is continued by the solvent reflux method. When the acid value of the contents of the reactor reaches 12, the reaction is terminated and the reactor is cooled. Alkyd resin B having a hydroxyl value of 95 was obtained. Plaxel H-1 (polycaprolactone) was added to 100 parts by weight of the alkyd resin B.

30 parts by weight of Daicel Chemical Industries, Ltd. (trade name) having a number average molecular weight of 10,000 was blended.

Then, a white enamel paint was prepared according to Example 1 (2) and tested according to Example 1 (3). The results are shown in Table 1.

Comparative Example 1 The procedure of Example 1 was followed except that polycaprolactone was not used. The results are shown in Table 1.

Comparative Example 2 Using the same equipment as in Example 1, 1,6 hexanediol 24
．． Charge 13.5 parts of 5L* opentyl glycol, 0.6 parts of trimethylolpropane, 2 s, o parts of adipic acid, 17.5 parts of m-hydrophthalic acid, and 19.0 parts of hexahydrophthalic anhydride, and reduce the temperature to 220C. Heat to. Condensed water is removed from the system through a rectification column. When the temperature of the rectification column falls below 80C, xylene is added to the reaction tank and the reaction is continued by the solvent reflux method. When the acid value reaches 7, the reaction is terminated and the mixture is cooled. An alkyd resin having a hydroxyl value of 55 was obtained.

Then, the same procedure as in Example 1 (2) and (3) was carried out using this alkyd resin and without using polycaprolactone. The results are shown in Table 1.

In addition, the blocking property was measured by placing several sheets of gauze on the coating film and placing a weight of 40ran in diameter and 500g on top of it.
Gauze marks on the coating film were observed after it was left in the atmosphere for 2 hours.

In addition, the flexibility at -1Or is 24 in an atmosphere of -10C.
After standing for a period of time, a rod with a diameter of 50 m was held in place and the presence or absence of cracks at the 180C bent portion was observed. Acid resistance was determined by dropping 0.2 cc of 5-thiosulfuric acid onto the coating film and
After leaving it for a while, the coating film on the dripping area was observed.

Gasoline resistance was determined by immersing a test piece in gasoline at 20C for 3 hours, and then observing the coating film.

Water resistance was determined by immersing a test piece in 40 tr water for 200 hours, and then observing the coating film.

As is clear from Table 1, the coating films of Examples 1 and 2 were glossy and
Blocking property, bending property at -100.

It showed excellent performance in all aspects of acid resistance, gasoline resistance, and water resistance.

On the other hand, Comparative Example 1 was obtained by removing polycaprolactone from Example 1 and was -10tl; low.

〔Effect of the invention〕

The thermosetting coating composition according to the present invention provides a coating film with excellent acid resistance, gasoline resistance, water resistance, and durability.

Claims (1)

[Claims] 1. A thermosetting coating resin composition containing an alkyd resin, a polyol resin, and an amino resin, wherein the alkyd resin has a hydroxyl value of 50 to 140, and as its components, general Formula (I) HO-(CH_2)-_nOH......(I) (However, in the formula, n indicates the number of repetitions of -(CH_2)-,
an integer from 4 to 10), an aliphatic dihydric alcohol represented by the general formula (II) HOOC-(CH_2)-_nCO
OH......(II) (in the formula, n is the same as above) represented by an aliphatic dibasic acid and the general formula (III) O-(CH_2)-_nC=O......(III ) (where n is the same as above) in an amount of 5 to 50% by weight, and the polyol resin has a number average molecular weight of 4,000 to 4,000. 100,000 polycaprolactone, and the polycaprolactone is the alkyl resin 100,000 polycaprolactone.
5 to 100 parts by weight of a thermosetting coating composition.