CN103102446B - A kind of car refinishing paint Hydroxylated acrylic resin and preparation method thereof - Google Patents

Abstract

A kind of hydroxy acrylic resin for automobile repair paint, wherein the weight ratio of each reactant is: alkyl methacrylate, 30-50 parts; hydroxy acrylate, 10-20 parts; styrene, 10-20 parts; Saturated carboxylic acid, 0.5-1.5 parts; Fluorine-containing acrylate, 1.0-3.0 parts; Initiator, 1-3 parts; Solvent, 30-40 parts. The present invention starts from the film-forming material resin of the coating, especially from the adjustment of the monomer structure of the resin to realize very fast surface drying and internal chemical crosslinking of the coating. The varnish prepared by using the resin of the present invention does not need to be baked. It can be sprayed for half an hour under low temperature conditions (5-15°C) to achieve the effects of no dust, no dust, full luster, and no loss of gloss. It can be finished after 4 hours Waxing and polishing. The varnish prepared by the resin of the present invention has the advantages of low shrinkage, high gloss, high distinctness of image, strong scratch resistance and the like in addition to ultra-fast drying performance.

Description

A kind of hydroxyacrylic resin for automobile repair paint and preparation method thereof

technical field

The invention relates to a resin for automobile repair paint, in particular to a low-temperature (5°C-15°C) ultra-fast-drying hydroxyacrylic resin for repair varnish. The resin is mainly used for high-grade automotive varnishes, and has super-curing performance, good paint film performance and excellent board surface state.

Background technique

Car refinish paint, as the name suggests, refers to the paint used for refinishing the original paint of the car body. It generally refers to spraying a metal primer on the middle coat, spraying a finish varnish immediately after flashing, and drying together. In the application of automotive refinishing paint, it often takes a period of time to dry the varnish after it is painted, and the subsequent polishing and other treatments can be carried out after drying. Therefore, the drying speed of the varnish often affects the work efficiency of car refinishing, which determines the quality of car repairing. time required. At the same time, as the last paint film of car repair, the finish varnish gives people an intuitive impression, and determines the appearance and durability of the composite coating of car repair paint.

The surface dry time of the existing car repair varnish after spraying is 60 minutes at a temperature of 25°C, and it can be delivered after being waxed and polished after drying overnight, which objectively prolongs the time for customers to pick up the car. In recent years, with the increasing automobile consumption and auto repair business, more and more auto repair shops have a strong demand to improve production efficiency, shorten delivery time, and at the same time ensure a good appearance of the paint film.

In order to solve the problem of rapid drying of varnish, US527986 discloses a preparation method of ultra-fast drying varnish, selects methyl methacrylate, butyl methacrylate, styrene, hydroxyethyl methacrylate monomers to prepare the glass transition temperature The temperature is 70°C, the number average molecular weight is 6231, and the weight average molecular weight is 12023. The hydroxyl acrylic resin and the isocyanate curing agent are formulated into a paint. Although this method improves the drying speed of the varnish through the hydroxyacrylic resin with a high glass transition temperature, the shrinkage of the paint film leads to a greater loss in appearance along with the increase in the drying speed.

CN102153691 A discloses a method for preparing an ultra-fast-drying varnish. The composition of the varnish is composed of a solvent, a modification aid, a varnish film-forming base material, a leveling agent, a drier, a light stabilizer and a curing agent according to a certain amount. weight percent composition. Although this method improves the drying speed of the varnish through the optimization of solvent composition, the introduction of modified cellulose acetate butyrate, and the introduction of isophorone diisocyanate curing agent, so as to achieve the purpose of ultra-fast dry; but compared with conventional varnishes, The cost of the varnish is relatively high and the drying speed of the paint film has not been significantly improved.

US6472493B1 discloses a method for preparing an ultra-fast-drying varnish. The composition of the paint consists of a solvent, a hydroxyacrylic resin, a polyester resin, a leveling agent, an amine catalyst, an organotin type drier, and a carboxylic acid type drier. And the curing agent is constituted by a certain weight percentage. In this method, a series of driers are compounded to achieve the effect of rapid drying and excellent appearance of the paint film. However, due to the introduction of a large amount of driers, the construction time and service life of the varnish are shortened. And the paint film is prone to yellowing, cracking, and poor scratch resistance during subsequent use.

Therefore, it is an urgent problem to be solved in the industry to vigorously develop a quick-drying car repair varnish with excellent comprehensive performance.

Contents of the invention

The object of the present invention is to provide a kind of hydroxyacrylic resin for ultra-fast-drying automotive refinish paint, and the prepared hydroxyacrylic resin for ultra-fast-drying automotive refinishing paint has low shrinkage, high gloss, and high distinctness of image after being used in varnishes. , Good scratch resistance and so on.

The object of the present invention is also to provide a preparation method of the above-mentioned hydroxyacrylic resin for automotive refinish paint.

The technical solution of the present invention is that the weight ratio of each reactant is: (A) alkyl methacrylate, 30-50 parts; (B) hydroxyacrylate, 10-20 parts; (C) styrene, 10-20 parts (D) unsaturated carboxylic acid, 0.5-1.5 parts; (E) fluorine-containing acrylate, 1.0-3.0 parts; (F) initiator, 1-3 parts; (G) solvent, 30-40 parts;

The preparation method includes: 1) Putting 25-30 parts of solvent into the reaction kettle and raising the temperature to 140-160 ° C; 2) Adding the mixture of the above-mentioned monomers in the weight ratio and 1-2.5 parts of the initiator, and the feeding time is 3-5 hours, the temperature is controlled at 140-160°C, 3) After the dropwise addition, keep warm in the reactor for 2-3 hours; 4) Add the remaining 0.1-0.5 parts of initiator and the remaining 5-10 parts of solvent, and keep warm for 3-4 hours; 5) Cool down to below 80°C and filter.

The alkyl methacrylate in the present invention is a methacrylic acid monomer containing 1-10 carbon atom esterification groups, including linear alkyl ester monomers, branched and cyclic alkyl ester monomers body.

The alkyl methacrylate described in the present invention is a mixture of one or more of methyl methacrylate, butyl methacrylate and isobutyl methacrylate.

The alkyl methacrylate described in the present invention is norbornyl methacrylate, 1,4-cyclohexanedimethanol monoacrylate, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, trimethylmethacrylate One or more mixtures of cyclohexyl esters.

The hydroxyacrylate in the present invention is one of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate and hydroxypropyl acrylate.

The unsaturated carboxylic acid in the present invention is one of acrylic acid, methacrylic acid, maleic anhydride and fumaric acid.

The fluorine-containing acrylate in the present invention is hexafluorobutyl acrylate, hexafluorobutyl methacrylate, trifluoroethyl methacrylate, dodecafluoroheptyl methacrylate, nonadecafluoroacrylate, trifluoromethyl One of acrylic.

The initiator described in the present invention is tert-butyl peroxybenzoate, azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide, di-tert-amyl peroxide, dimethyl-2,5- One or more mixtures of bis(tert-butylperoxy)hexane.

The solvent of the present invention can be selected from one or more of xylene, trimethylbenzene, pentyl ester, isopropyl ester, n-butyl ester, ethylene glycol ethyl ether ester or propylene glycol methyl ether ester mixture.

The advantages of this invention are:

1) The drying speed of the existing automotive refinish paint varnish generally starts from the optimal resin, the structure of the curing agent, catalyst, solvent, etc., to achieve the purpose of fast repair and low temperature curing. And the present invention starts from the film-forming substance resin of the paint, especially from the adjustment of the monomer structure of the resin to achieve very fast surface drying and internal chemical crosslinking of the paint.

2) It is reported that the viscosity of acrylic resin is reduced and the compatibility with other types of resins (alkyd, polyester) is improved by introducing naphthenic methacrylic acid monomer in the synthesis of acrylic resin. And the present invention is to realize the rapid curing and low polymerization shrinkage of the hydroxy acrylic resin for automotive refinish paint by introducing branched and naphthenic monomers in the synthesis of the hydroxy acrylic resin. The principle is: branched monomers, especially isomeric monomers, have a higher glass transition temperature and solvent release than linear monomers. And naphthenic monomers, especially norbornyl ester monomers, have a unique bridged ring structure. In the structure of this type of isobornyl (meth)acrylate, the double bond of the acrylic acid moiety can be copolymerized with many other unsaturated monomers by free radical polymerization. The ester alkoxy part is a huge non-polar bicycloalkyl group. The nonpolar bicycloalkyl group with large molecular volume and large molecular weight has extremely low polymerization shrinkage and configuration retention. In addition, the bicycloalkyl group gives polymerization The chain of matter is protected by strong steric hindrance while weakening the force between molecules and improving the solvent release. Makes hydroxyacrylic resins have excellent film appearance and excellent drying speed.

In the formula, R1 represents a hydrogen atom or a methyl group. R2 represents an alkyl group of 1-8 carbon atoms, _R3 represents a hydrogen atom or a methyl group, and _R4 represents a cycloalkyl group.

3) In order to improve the drying speed of hydroxy acrylic resin, the conventional method is to choose acrylic resin with low hydroxyl content (OH% is 2%-2.7%) and high glass transition temperature (70°C-90°C). However, acrylic resins with low hydroxyl content and high glass transition temperature tend to have relatively high molecular weight and viscosity, and after cross-linking with isocyanate curing agents to make paints, the gloss, distinctness of image are poor, and the shrinkage is severe. The hydroxyl acrylic resin prepared by the method of the present invention has a glass transition temperature of 70-90°C, a number-average molecular weight of 2000-3000, and a solid content of 60-70% due to branching and the introduction of cycloalkyl monomers. Under certain conditions, the viscosity of the resin is only 4000-8000 mPa·s. The low viscosity resin is convenient for the design of high solid content and low viscosity paint formulation, and also makes the leveling and fullness of the resin better. The obtained varnish has the characteristics of high gloss, high vividness of image, strong scratch resistance and the like.

4) Hydroxy acrylic resins with fast drying properties tend to have poor long and short wave leveling, and the general solution is to add leveling aids. The leveling aids in the existing paint formulations are generally acrylic leveling agents, silicone leveling agents, and fluorine-modified leveling agents. Because fluorine compounds have the ability to strongly reduce the surface tension of polymers and excellent surface scratch resistance, they become the best in leveling agents, but the compatibility of physically blended fluorine-modified leveling agents with resin bulk is limited. . Based on such thinking, the present invention introduces fluorine-containing acrylic monomer into the molecular chain of acrylate polymer through chemical reaction by introducing fluorine-containing acrylic monomer into the formula, and completes the modification of acrylate in terms of structure and composition. The modification of polymers can achieve the effect of molecular modification. Chemical modification significantly improves the compatibility between the two phases, controls the surface migration of fluorine molecular chains and its microscopic morphology to a certain extent, and has various excellent properties that cannot be compared with the physical addition of fluorine-containing leveling agents. In this way, the high glass transition temperature hydroxyacrylic resin achieves excellent leveling and strong scratch resistance by virtue of its own fluorine-containing acrylate groups during the rapid drying process.

5) Existing quick-drying varnishes for automotive refinish paint are generally baked for 30 minutes (50°C-60°C), and the surface of the paint film can achieve the effect of waxing and polishing after cooling for half an hour. Due to the investment in the baking room and energy consumption, the main scope of use of this type of varnish is mainly limited to large repair shops and 4S stations. Now there are some products on the market that can be sprayed for more than 5-8 hours at room temperature at 25°C to achieve light The effect of waxing and polishing, but the yellowing of the paint film becomes heavier, the mid-term loss of light (after 1-3 months) is serious, and the leveling and fullness of the paint film are poor, so the use of this type of quick-drying varnish is mainly limited to local repairs and Quick fix. However, the finished paint prepared by the hydroxyacrylic resin of the present invention does not need to be baked, and it can be sprayed for half an hour under low temperature conditions (5°C-15°C) to achieve the effect of no dust, no dust, full luster, and no loss of gloss. , After 4 hours, it can be waxed and polished. In view of the fact that the temperature in the garage in the central and northern regions of China is basically in the range of 5°C-20°C in autumn and winter and many repair shops do not have baking equipment and conditions, this kind of refinish paint products have broad prospects in terms of energy saving and consumption reduction and market application .

specific embodiment

Example 1

Put 25kg of xylene into the reaction kettle, heat up to 138°C and reflux. Take 10kg methyl methacrylate, 25kg isobutyl methacrylate, 5kg cyclohexyl methacrylate, 1kg acrylic acid, 10kg styrene, 13kg hydroxyethyl methacrylate, 1kg trifluoroethyl methacrylate, 3kg over Oxygenated tert-butyl benzoate is added in the above-mentioned reaction kettle after being mixed evenly, and the time of dropping is 3 hours, and the temperature in the reaction kettle is controlled at 138° C. The benzoyl peroxide of 0.1kg is cooled to below 80 ℃ after 138 ℃ of insulations in reactor again for 3 hours, and is filtered to take out material; Promptly obtains the hydroxyacrylic resin for ultra-quick-drying type automobile refinish paint of the present invention.

Example 2

15 kg of xylene and 10 kg of propylene glycol methyl ether acetate were put into the reaction kettle, and the temperature was raised to 145° C. for reflux. Take 16.5kg methyl methacrylate, 10kg n-butyl methacrylate, 10kg norbornyl methacrylate, 0.5kg maleic anhydride, 15kg styrene, 10kg hydroxypropyl methacrylate, 3kg hexafluorobutyl acrylate Ester and 2.5 kg of di-tert-butyl peroxide were mixed evenly and then added to the above reaction kettle. The time for the dropwise addition was 4 hours, and the temperature in the reaction kettle was controlled at 145°C. 10kg of propylene glycol methyl ether acetate and 0.1kg of di-tert-butyl peroxide, at 145 DEG C, in the reactor for 3 hours, then cool down to below 80 DEG C, filter and extract; obtain the ultra-fast drying type of the present invention Hydroxy-acrylic resins for automotive refinish paints.

Example 3

Put 25kg of propylene glycol methyl ether acetate into the reaction kettle, heat up to 148°C and reflux. Take 15kg methyl methacrylate, 15kg isobutyl methacrylate, 5kg tert-butylcyclohexyl methacrylate, 1kg methacrylic acid, 10kg styrene, 16kg hydroxyethyl methacrylate, 3kg hexafluorobutyl methacrylate , 2.5 kg of di-tert-butyl peroxide are mixed evenly and then added to the above reaction kettle, the time for dropping is 4 hours, and the temperature in the reaction kettle is controlled at 148°C. Propylene glycol methyl ether acetate and 0.1kg of di-tert-butyl peroxide are cooled to below 80°C after being kept warm for 4 hours at 148°C in the reactor, and the material is filtered and taken; Hydroxy-acrylic resins for refinish paints.

Example 4

Put 25kg of xylene into the reaction kettle, heat up to 138°C and reflux. Take 15kg methyl methacrylate, 15kg isobutyl methacrylate, 5kg tert-butylcyclohexyl methacrylate, 1kg methacrylic acid, 10kg styrene, 16kg hydroxyethyl methacrylate, 3kg hexafluorobutyl methacrylate , 2 kg of di-tert-amyl peroxide mixed evenly and then added to the above reaction kettle, the dropwise addition time is 5 hours, the temperature in the reaction kettle is controlled at 138 ° C, after the dropwise addition, keep the temperature in the reaction kettle for 2 hours; add 10kg of propylene glycol Methyl ether acetate and 0.1kg of di-tert-amyl peroxide are kept at 138°C for 4 hours in the reactor, and then the temperature is lowered to below 80°C, and the material is filtered and extracted; the ultra-fast-drying car repair of the present invention is obtained Paint with hydroxy acrylic resin.

Example 5

Put 15kg of xylene and 10kg of trimethylbenzene into the reaction kettle, raise the temperature to 142°C and reflux. Take 25kg methyl methacrylate, 3kg n-butyl methacrylate, 5kg norbornyl methacrylate, 1kg methacrylic acid, 10kg styrene, 19kg hydroxyethyl methacrylate, 2kg hexafluorobutyl methacrylate, 2.5kg of tert-butyl peroxybenzoate is mixed evenly and added to the above reaction kettle. The time for dropping is 5 hours. The temperature in the reaction kettle is controlled at 138°C. The di-tert-amyl peroxide of trimethylbenzene and 0.1kg is cooled to below 80 ℃ after being incubated again in the reactor at 138 ℃ for 4 hours, and the material is filtered and taken out; promptly obtains the ultra-quick-drying type car refinish paint of the present invention. Hydroxy acrylic resin.

Application example

The refinishing paints of Examples 1-5 were made into finished paints with hydroxyacrylic resins, mixed with curing agent at a ratio of 4:1, sprayed on polished tinplate plates, and dried in a constant temperature room at 10°C. The performance tests of the paint film are as follows.

The drying speed is measured according to GB1728-1979 "Determination of drying time of paint film and putty film".

The hardness is determined according to GB/T6739-2006 "Determination of Paint Film Hardness of Paints and Varnishes by Pencil Method".

Adhesion is measured according to GB/T 9286-1998 "Paint and Varnish Film Cross-cut Test".

Gloss is measured in accordance with GB 1743-1979 (1989) "Determination of Glossiness of Paint Films".

Claims (5)

1. a kind of car refinishing paint Hydroxylated acrylic resin, it is characterised in that the weight proportion of each reactant is：(A) methyl-prop Olefin(e) acid Arrcostab, 30-50 parts；（B）Hydroxy acrylate, 10-20 parts；(C) styrene, 10-20 parts；(D) unsaturated carboxylic acid, 0.5-1.5 parts；（E）Fluorinated acrylate, 1.0-3.0 parts；（F）Initiator；（G）Solvent, 30-40 parts；The unsaturated carboxylic acid For methacrylic acid；The alkyl methacrylate is norbornyl ester, 1,4 cyclohexane dimethanol list propylene One in acid esters, cyclohexyl methacrylate, t-butyl cyclohexyl base ester, methacrylic acid trimethylcyclohexylidene base ester Plant or a variety of mixtures；The fluorinated acrylate is hexafluorobutyl acrylate, Hexafluorobutyl mathacrylate, methacrylic acid One kind in trifluoro ethyl ester, dodecafluoroheptyl methacrylate；Its preparation method includes：1）By 25-30 parts of input reactions of solvent In kettle, 140-160 DEG C is warming up to；2）The mixture of above-mentioned weight proportion monomer and 1-2.5 parts of initiators is added, feed time is 3-5 hours, 140-160 DEG C of reaction temperature；3）After charging is finished, in reactor inside holding 2-3 hours；4）Add 0.1-0.5 parts Initiator and 5-10 parts of solvents, then it is incubated 3-4 hours；5）It is cooled to less than 80 DEG C, filtering.

2. car refinishing paint Hydroxylated acrylic resin according to claim 1, it is characterised in that：The hydroxy acrylate For one kind in hydroxyethyl methacrylate, hydroxy-ethyl acrylate, hydroxy propyl methacrylate, hydroxypropyl acrylate.

3. car refinishing paint Hydroxylated acrylic resin according to claim 1, it is characterised in that：The initiator is peroxide Change t-butyl perbenzoate, azodiisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, di t-amyl peroxide, diformazan Base -2,5- is double（T-butyl peroxy）One or more mixtures in hexane.

4. car refinishing paint Hydroxylated acrylic resin according to claim 1, it is characterised in that：The solvent chooses diformazan The one or two of benzene, trimethylbenzene.

5. the preparation method of car refinishing paint Hydroxylated acrylic resin described in a kind of claim 1, it is characterised in that including：1） By in 25-30 parts of input reactors of solvent, 140-160 DEG C is warming up to；2）Add above-mentioned weight proportion monomer and 1-2.5 parts of initiations The mixture of agent, feed time is 3-5 hours, and temperature control is at 140-160 DEG C；3）After completion of dropping, in reactor inside holding 2-3 hours；4）0.1-0.5 parts of initiators and 5-10 parts of solvents are added, then are incubated 3-4 hours；5）It is cooled to less than 80 DEG C, filtering .