JPH04139279A - Paint composition - Google Patents

Abstract

PURPOSE:To obtain a paint composition having improved abrasion resistance of an acid-epoxy paint having excellent acid resistance by using a compound having carboxylic acid anhydride group and a specific oligomer having branched chain of terminally functional group as film-forming components. CONSTITUTION:The objective paint composition having excellent weather resistance, solvent resistance and water resistance contains, as film-forming components, (A) a compound having carboxylic acid anhydride group and preferably consisting of a copolymer of a monomer having a radically polymerizable unsaturated bond and a carboxylic acid anhydride group and other copolymerizable monomer and (B) an oligomer having a molecular weight of 400-2,000 and a molecular weight distribution of <=2, containing >=4.0mol of urethane bond and produced by reacting hydroxyl group with >=2.0mol of ring- opened lactone and/or isocyanate having lactone-modified hydroxyl group. The glycidyl group equivalent of the component B is <=666 based on 1,000g of the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coating composition that improves the scratch resistance of an acid-epoxy coating that has excellent acid resistance.

(Prior Art) In recent years, deterioration of paint films due to acid rain has become a problem. This mechanism is due to hydrolysis of the coating film, and the higher the acidity of the system and the higher the temperature, the more likely it is to occur.

To explain the reason for this, for example, in the case of forming a cured film with melamine and polyol: The condensed water produced in the presence of the compound evaporates, the equilibrium shifts from (I) to (n), and the crosslinking reaction proceeds. After the coating film is formed, if excess water is added to the system by rain in state (n), the equilibrium changes from (II) to (
The process moves to I), and the hydrolysis of the coating film is accelerated. Therefore, this hydrolysis reaction is influenced by the acidity and temperature of the rain.

(Problems to be Solved by the Invention) By the way, as a paint for improving scratch resistance, a paint containing an alkoxy monomeric melamine mixed with a polyol component has been proposed (Japanese Patent Application Laid-Open No. 64-43373). For some reason, it has a problem of lacking acid resistance.

Therefore, materials that do not crosslink through condensation reactions, such as polyol and isocyanate systems, acid-epoxy systems, cationic and anionic polymerization systems of epoxy systems, and acid anhydride-polyol systems, may be selected, but they have the disadvantage of lacking scratch resistance. .

Therefore, an object of the present invention is to provide a coating composition that can form a coating film that has excellent scratch resistance and acid resistance.

(Means for Solving the Problems) The present invention was made based on the fact that in order to solve the above problems, it is important to lower the molecular weight and improve the crosslinking density by utilizing a reaction that does not crosslink in the condensation reaction. (a) A compound having a carboxylic anhydride group, and (h) a hydroxyl group reacted with 2.0 moles or more of a ring-opening lactone and isocyanate obtained by modifying the hydroxyl group with a lactone and having a glycidyl equivalent of 666 or less per 1000 g of resin. 4. Contains at least one of 0 moles or more of urethane bonds, and has a molecular weight of 400 to
2000, a coating composition containing an oligomer having a molecular weight distribution of 2 or less.

According to the present invention, the star-shaped oligomers, which are the components (a) and (b), form a three-dimensional cured film with short distances between crosslinks and form a regular network, and have good recovery properties. As a result of forming a highly elastic coating film, the occurrence of scratches can be suppressed as much as possible by elastically responding to the scratching method.

In the present invention, the oligomer, which is the component (b) above, is a low-molecular resin having branched chains grown from the central element in three or more directions by modification, that is, addition, of ring-opening lactones. It refers to something that has a glycidyl group and a hydroxyl group, which are functional groups.

The appropriate molecular weight of the oligomer is 400 to 2,000. If it is less than 400, painting workability will be reduced and it will sometimes become volatile during painting or baking, and if it is more than 2000, scratch resistance will be reduced. Furthermore, the molecular weight distribution, that is, the weight average molecular weight Mw/number average molecular weight Mn, must be 2 or less because the distribution of the polymer molecular weight in the polymerization with the component (a) below is suppressed as small as possible, and the molecular weight distribution is uniform. This is to suppress a decrease in the scratch resistance of the coating film. Furthermore, the reason for modifying the hydroxyl group with ring-opening lactone so that it contains 2.0 or more ring-opening lactone per 1000 g of resin is to soften the crosslinks and impart elasticity.
Glycidyl group, equivalent weight 666 or less, hydroxyl group 1.
The reason for setting the amount to be 0 mole or more is to ensure a certain number of crosslinking reaction points with component (a) below and to prevent deterioration of water resistance and scratch resistance.

As the above component (a), monomers having radically polymerizable unsaturated bonds and carboxylic anhydride groups, such as itaconic anhydride and maleic anhydride, are copolymerized with other copolymerizable monomers. preferable. Examples of the copolymerizable monomer include styrene, C-methylstyrene, acrylic ester, methacrylic ester, acrylamide, and methacrylamide. The copolymerization may be performed by a known method such as radical polymerization. The average molecular weight is preferably 1000 to 2000.

Component (b) above is generally produced as follows. One of these methods is to use polyol (■) as a starting material and add a ring-opening lactone (■) to the hydroxyl group to form a modified terminal hydroxyl group (see ■'). Acid anhydride ■ is added to form a carboxylic acid group (see ■), and a diisocyanate ■ or ■′ is added to a monoepoxy alcohol compound ■ having a glycidyl group at the end modified with a ring-opening lactone ■. Adding a compound (2) having a glycidyl group at both ends or a compound (2) having a glycidyl group at one end and an isocyanate group at the other end to produce a star-shaped oligomer [phase], or reacting the above (2) with (2) to produce 0''. I can do it.

The other method is to react an alkoxysilane compound (2) having a glycidyl group with a monoepoxy alcohol (2) modified with Epoquin alcohol (2) and a ring-opening lactone (2) to obtain (2), as shown in production process (I[). Then, by reacting (1) with acid and hydroxyl acid, star-shaped oligomer (2) can be produced.

(Leaving space below) Engraving of the clear image of the specification - Purification production process (III) of the Issei specification CR3 (CH2)5 C, H7- to -0-CH2-H-H-OH The above polyol (■) is glycerin , trimethylolethane, trimethylolpropane, trishydroquinemethylaminomethane, pentaerythritol, and dipentaerythritol.

The lactone ■ added as a ring-opening lactone is C-
caprolactone, I-methyl-2-valerolactone, 1
Specific examples include -valerolactone, I-caprolactone, γ-caprolactone, γ-methylvalerolactone, β-propiolactone, and γ-butyrolactone.

Specific examples of the acid anhydride (2) include cono-phosphoric anhydride, trimellitic anhydride, phthalic anhydride, pyromellitic anhydride, and hexahydroxyphthalic anhydride.

Specific examples of the monoepoxy alcohol include 2,3-epoxybutanol and 3,4-epoxybutanol.

Examples of diisocyanates include hexamethylene diisocyanate, inphorone diisocyanate, and kylene diisocyanate.
Specific examples include anate and lysine diisonate.

Alcoquinrane compounds having a grindyl group at the terminal include N-glycidyl-N, N-bis[3-(methyldimethoxynryl)propyl-1 amine, N-glycidyl-N,
N,N-bis[3-0rimethquinsilyl)propyl 1 amine, 3-grindquinproviltrimethquinanran
3-Glinodoquinpropylmethyldimethoxysilane, 3
-glycidoxypropyldimethylmethoxysilane, 3-
(N,N-diglycidyl)aminopropyltrimethquine silane is mentioned as a specific example. Also, instead of the above methoxysilane compound, can you use epoxy-containing siloxane oligo?
- may be used as XC96-709, XC96-710 (manufactured by Toshiba Silicone), or TSC9906 (manufactured by Toshiba Silicone).

Hereinafter, the present invention will be explained in detail based on examples.

Production Example 1 Synthesis of Polymer (a)-I Containing Carboxylic Anhydride Group 120 parts by weight of butyl acetate was charged into a 112 reaction vessel equipped with a thermometer, a stirrer, a cooling tube, and a nitrogen introduction tube, and the temperature was heated to 115°.
21 parts by weight of n-butyl acrylate, n-
A seven-mer starting compound consisting of 95 parts by weight of butyl methacrylate, 34 parts by weight of 2-ethylhequinyl methacrylate, 45 parts by weight of itaconic anhydride, 60 parts by weight of dioxane and 10 parts by weight of t-butylperoxy-2-ethylhexanoate. The agent solution was added dropwise over a period of 3 hours, and stirring was continued for an additional 2 hours to obtain an acrylic resin with a nonvolatile content of 53% and a number average molecular weight of 5t500.

Production Examples 2 and 3 Polymers containing carboxylic anhydride groups (a) II and ■
A polymer containing a carboxylic anhydride group was obtained in the same manner as in Synthesis Production Example 1 using the components shown in Table 1.

(Leaving space below) Table note 1 = Butylperoxy 2-ethylhexanoate A I BN: Azobisisobutyronitrile Production Example 4 Synthesis of component (b)-I ■ 2. 3-Epoquine propanol 148 with hexamethylene Reaction of diison abut 168 yields product A.

■On the other hand, put Ky/Ren 40 into a flask, react with 6.8 of pentaerythritol, 11.4 of ε-caprolactone, and 0.5 of tetrabutyl titanate at 120°C for 1 hour, and add cono-phosphoric anhydride to the reaction product. 1O was added thereto, and the above product A was added thereto to obtain an oligomer with the following physical properties.

Molecular weight 1200, epoxy equivalent weight 588, hydroxyl value 184, ring-opened lactone 300, molecular weight distribution 1.3 Production Example 5 Component (b) 40 synthetic xylene of m was put in a flask, 5.9 g of pentaerythritol was added, refluxed, anhydrous co/ Add 13 parts of phosphoric acid and stir for 1 hour under reflux. Furthermore, 41 parts of the product A obtained in Production Example 4 was added to obtain an oligomer with the following physical properties: molecular weight 1400, epoxy equivalent weight 470, hydroxyl value 160.
, ring-opened lactone 476, molecular weight distribution 1.2 Production Example 6 Component (b) 1240 parts of the synthetic compound of m was placed in a flask, 18.6 parts of 2,3-epoxypropanol and 14.3 parts of ε-caprolactone were added. Add 0.5 part of tetrabutyl titanate and stir at reflux for 2 hours. Next, 19.7 parts of 3-glyndoxypropyl trimethoxy V-lan is added and stirred for 1 hour. Thereafter, 7.4 parts of butanoic acid was added and stirred for 1 hour to obtain an oligomer with the following physical properties.

Molecular weight 700 Molecular weight distribution 1.3 Hydroxyl value 80 Epoxy equivalent 232 Ring-opened lactone 467 Production example 7 Synthesis of component (b) IV Put 40 parts of xylene in a flask, add 13.3 parts of 2,3-epoxypropanol, and ε-caprolactone 27 Add 0.5 part of tetrabutyl titanate and stir at reflux for 2 hours. Next, 14.1 parts of 3-grindquinproviltrimethquine silane is added and stirred for 1 hour. Thereafter, 5.2 parts of butanoic acid was added and stirred for 1 hour to obtain an oligomer with the following physical properties.

Molecular weight 1000 Molecular weight distribution 1.3 Hydroxyl value 56 Epoxy equivalent 333 Ring-opened lactone 250 Production example 8 40 parts of xylene was placed in a flask, 10 parts of 2.3-epoxypropanol and 31 parts of ε-caprolactone were added.
Add 0.5 part of tetrabutyl titanate and add 2 parts under reflux.
Stir for an hour. Next, 16 parts of 3guri/doki/propyltrimethoxy7norane were added and stirred for 1 hour. after that,
2.5 parts of butanoic acid was added and stirred for 1 hour to obtain the following oligomer with a small amount of ○H groups.

Molecular weight 1100 Molecular weight distribution 1.3 Hydroxyl value 31 Epoxy/equivalent 300 Ring-opened lactone 225 Production example 9 ■2.148 parts of 3-epoquinoprobanol are reacted with 168 parts of hexamethylene diisocyanate to obtain product A.

■On the other hand, put 40 parts of ky/lene into a flask, 8.1 parts of pentaerythritol, 27.1 parts of ε-caprolactone,
0.5 of tetrabutyl titanate was reacted at 120° C. for 1 hour, 6.0 of succinic anhydride was added to the reaction mixture, and the above product A was added to this to obtain the following epoxy/low oligomer.

Molecular weight 1100, Epoquine equivalent 1111, hydroxyl value 203
, ring-opened lactone 220, molecular weight distribution 1.4 (Production Example 10) (2) 148 parts of 2,3-epoxyprobanol is reacted with 222 parts of impondiison abut to obtain product B.

(4) Put 40 parts of the above 21 flask into a flask, then add 8.0 parts of pentaerythritol and 11.8 parts of succinic anhydride, and react under reflux for 1 hour. 18.5 parts of the product A obtained in Production Example 9 and 821.7 parts of the above-mentioned product were added to this mixed solution and reacted to obtain an oligomer having the following physical properties.

Molecular weight 1100 Molecular weight distribution 1.3 Hydroxyl value 203 Epoquine equivalent 500 Ring-opening lactone equivalent till (Production Example 11) 100 parts of the oligomer obtained in Production Example 5 was placed in a flask,
Add 5 parts of hexamethylene diisocyanate and heat to 80°C.
After stirring for 1 hour, the following oligomer with a large molecular weight distribution was obtained.

Molecular weight: 3200 Molecular weight distribution: 2.4 Hydroxyl value: 145 Epoxy/equivalent: 470 Ring-opened lactone equivalent: 520 (Example) A clear paint was prepared with the formulation shown in Table 2 below, and the performance of the resulting paint film was evaluated.

(Margin below) Table 2 (Comparative Example) Preparation of clear paint A clear paint was prepared according to the formulation shown in Table 3 below, and the performance of the resulting coating film was evaluated.

(Margin below) Table 3 (Paint test) (1) Preparation of base coat paint 100 parts of Kinroll was charged into a four-bottle flask equipped with a stirrer, a thermometer and a condenser, and heated to 100°C. Here, 1210 parts of Ste, 10 parts of methyl methacrylate, 30 parts of butyl acrylate, 35 parts of inbutyl acrylate, 1 part of 2-vitroquinomethacrylate
2 parts of methacrylic acid, 3 parts of azobisbutyronitrile, and 2 parts of azobisbutyronitrile were mixed, added dropwise over 4 hours, and kept at the same temperature for 6 hours. A resin solution was obtained.

For 180 parts of the acrylic resin solution obtained in this way,
37.5 parts of Kneepan 20SE-60 (butylated melamine resin, solid content 60%) manufactured by Mitsui Toatsu Chemical Co., Ltd. and 16.3 parts of "Aluminum Paste" 716ONJ manufactured by Toyo Aluminum Chemical Co., Ltd. as aluminum paste were mixed in a stirrer. ,
Stir and mix.

Furthermore, it was diluted with a mixed solvent consisting of 15 parts of ethyl acetate, 40 parts of toluene, 35 parts of Trubec 100 (manufactured by Esso Corporation) and 10 parts of Cellulose Acetate, and the viscosity was adjusted to 14 seconds (Ford Kambe #4/25°C). A base coat paint was obtained.

(2) Formation of paint film The base coat paint was applied to a steel plate for automobile bodies with cationic electrodeposition paint, and then baked onto the object to be coated. The paint samples A1-6 and B1-4 prepared in the above manner were applied wet-on-wet, and after setting for 10 minutes, they were heated at 140° C. for 20 minutes to obtain samples.

The above coating film was tested for scratch resistance, weather resistance, solvent resistance, and water resistance.

Move the paint film surface back and forth 1000 times with a scratch-resistant car wash brush, observe the paint film after cleaning, and mark it qualitatively with ◎ if there are no scratches, △ if there are some scratches, and × if there are scratches. It was shown to.

After testing for 3000 hours with a weather resistant sunshine weather meter, the gloss retention rate was displayed.

Impregnated with solvent-resistant Kijiroru: After rubbing the surface of the coating film with gauze 50 times, those with no scratches were marked ◎, those with some scratches were marked Δ, and those with scratches were marked ×.

Water Resistance The coating film was immersed in warm water at 50°C for 48 hours and evaluated as ◎ if there was no abnormality, △ if there was slight whitening, and X if there was significant blistering. The results are shown in Table 4.

Table 4 (Effect of the invention) As is clear from the results in Table 4, the oligomer (b) having a branched terminal functional group reacted with the compound (a) having a carboxylic anhydride group has a molecular weight of 400 to 2000, Hydroxyl value 56 or more and epoxy equivalent 666 or less, My/Mn<
2.0, when the ring-opened lactone modification equivalent in the molecule is 500 or less, it has excellent scratch resistance, weather resistance, solvent resistance, and water resistance, but when a star-shaped oligomer that is not in the above range is used, it has particularly poor scratch resistance. It can be seen that the properties and weather resistance deteriorate (Table 4B1
-4)). This is because Bl has few hydroxyl groups, B2 has many epoxy groups, B3 has a small amount of ring-opened lactone, and B4 has too large a molecular weight and molecular weight distribution.

Claims (1)

[Claims] 1. (a) a compound having a carboxylic anhydride group; (b)
Contains at least one of a glycidyl group equivalent of 666 or less per 1000 g of resin, 2.0 moles or more of a ring-opened lactone obtained by modifying a hydroxyl group with a lactone, and 4.0 moles or more of a urethane bond obtained by reacting an isocyanate with a hydroxyl group, and has a molecular weight of 4.
00 to 2000, and an oligomer having a molecular weight distribution of 2 or less as a film-forming component. 2. The coating composition according to claim 1, wherein the component (a) is a copolymer of a monomer having a radically polymerizable unsaturated bond and a carboxylic anhydride group and another copolymerizable monomer. 3. Component (b) is an oligomer having a branched chain having a terminal glycidyl group obtained by adding a compound having a glycidyl group to a terminal hydroxyl group modified by adding a ring-opening lactone to the hydroxyl group of a polyol. The coating composition described. 4. The coating composition according to claim 1, wherein the component (b) is an oligomer obtained by adding a monoepoxy alcohol compound modified with a ring-opening lactone to the alkoxy group of an alkoxysilane compound having a glycidyl group.