JPS63162768A - Coating composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. which gives a coating film having excellent resistance to corrosion, water and solvents, by emulsion-polymerizing a specified monomer with an ethylenically unsaturated monomer copolymerizable therewith. CONSTITUTION:1-80wt% monomer (A) of the formula (wherein R1 is H or CH3; R2 is a 1-8C alkyl; R3 is a 2-8C alkylene) (e.g., butylcarbamoyloxyethyl acrylate) is emulsion-polymerized with 20-99wt% ethylenically unsaturated monomer (B) copolymerizable therewith (e.g., ethyl acrylate) in the presence of an emulsifying agent and a radical generating catalyst (e.g., t-butyl hydroperoxide) at 100 deg.C or lower, pref. 30-90 deg.C for at least 2hr. If desired, the pH of the polymn. mixture is adjusted to 5-10 with a base to obtain the title compsn. The compsn. is suitable for use in coating metal to impart corrosion resistance and paper, fiber, wood, slate board, etc. to impart resistance to moisture and water thereto. Further, it is suitable for use in coating the surfaces of glass and plastics and as a binder for slurry and pigment.

Description

Detailed Description of the Invention (a) Object of the Invention (Field of Industrial Application) The present invention relates to a coating composition that is applied to the surfaces of various articles such as metals, and the coating composition of the present invention The thing is
It provides a coating film with excellent corrosion resistance, water resistance, solvent resistance, etc., and is widely used in industries that handle metal products such as the automobile industry and electrical equipment manufacturing industry, and industries that handle wood products such as furniture wood industry. It is something that is used.

<Prior Art> Conventionally, various water-soluble resins and emulsion-type resins have been coated on the surfaces of various articles to impart corrosion resistance, water resistance, and the like.

However, all of these resins have major problems. In other words, since water-soluble resins have many hydrophilic groups and relatively low molecular weight, they have poor corrosion resistance and solvent resistance unless they are crosslinked by adding melamine, etc., and emulsion-type resins have a high resistance to metals due to the emulsifier they contain. Corrosion resistance, paint film adhesion, water resistance, etc. cannot be expected.

On the other hand, in order to improve corrosion resistance, water resistance, and solvent resistance, for example, compounds having two or more ethylenically unsaturated groups may be copolymerized to have a high molecular weight, or compounds containing epoxy groups, amide groups, methylolamide groups, etc. A method is used in which ethylenically unsaturated monomers are copolymerized and crosslinked during polymerization, film formation, or after film formation. However, even with these methods, if a large amount of the monomer is used in emulsion polymerization, it is difficult to proceed smoothly with the polymerization, and as the crosslinking density increases, the film becomes harder than necessary, and other There is a limit to the improvement in physical properties that can be obtained, such as hindering the physical properties of . Furthermore, there are many crosslinking agents as additives, but their high reactivity causes poor liquid stability and limits their practical use in order to exhibit excellent properties.

<Problems to be Solved by the Invention> The present inventors have solved the above-mentioned problems of conventional coating compositions, and have developed a coating composition that provides excellent corrosion resistance, excellent solvent resistance, water resistance, etc. Various studies were conducted in order to find a coating composition that would provide a coating film with a clear coating.

(B) Structure of the Invention Means for Solving Problems> The present inventors have discovered that a coating composition comprising an emulsion polymer containing a specific acrylate having a urethane bond (hereinafter referred to as urethane acrylate) as a constituent component The present invention was completed after discovering that the above requirements could be satisfied.

That is, the present invention relates to a coating composition characterized by comprising an emulsion polymer comprising 1 to 80% by weight of the following monomers and 20 to 99% by weight of the following monomer (B). be.

R8 within the monomer (However, R1 is a hydrogen atom or a methyl group, R2 is an alkyl group having 1 to 8 carbon atoms, and R5 is an alkylene group having 2 to 4 carbon atoms.) Monomer (B) Monomer Ethylenically unsaturated monomer 0 urethane acrylate copolymerizable with polymer (5) The urethane acrylate used in the present invention is represented by the following structural formula.

R.

(However, R3 is a hydrogen atom or a methyl group, R7 is an alkyl group having 1 to 8 carbon atoms, and R1 is an alkylene group having 2 to 4 carbon atoms.) Preferably, R1 is a lower alkyl group having 1 to 4 carbon atoms, especially a butyl group, and R8
is an ethylene group.

These urethane acrylates are disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 60-1
It can be easily produced by the method described in JP-A-55276 and JP-A-58-79063, and commercially available butylcarbamoyloxy ether acrylate, butylcarbamoyloxy ethyl methacrylate, etc. can also be used in the present invention. You can.

The amount of urethane acrylate in the emulsion polymer is 1 to 80"
yt*s, and if it is less than 1% by weight, it is insufficient to impart corrosion resistance, solvent resistance, water resistance, etc., and 80% by weight.
If the amount is more than 1, it is difficult to gel during emulsion polymerization and obtain a polymer.

A particularly preferred range is 2 to 50 folds of fitqb.

O Ethylenically Unsaturated Monomer Examples of ethylenically unsaturated monomers used in the present invention include the following. These are selected depending on the purpose, copolymerizability, etc., and one or more types are used.

1) α/β-unsaturated carboxylic acid esters, such as methyl acrylate, n-tyl acrylate, n-butyl acrylate,
Alkyl esters of acrylic acid or methacrylic acid such as isobutyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, and 2-ethylhexyl methacrylate. hydroxyalkyl acrylates and methacrylates such as hydroxyglobyl acrylate, amino group-containing esters of dimethylaminoethyl methacrylate, glycidyl group-containing esters such as glycidyl methacrylate, and esters of maleic acid, fumaric acid, and itaconic acid.

2) Amides of α/β-unsaturated acids, such as acrylamide, methacrylamide, maleic acid amide and maleic imide.

3) Substituted amides of unsaturated carboxylic acids, such as N-methylolacrylamide and methacrylamide, diacetone acrylamide, N-butoxymethylacrylamide, etc.

4) Vinyl esters such as vinyl acetate, vinyl propionate and vinyl chloride.

5) Nitriles of α/β-unsaturated carboxylic acids, such as acrylonitrile, methacrylaterile, etc.

6) Hinyl ethers, such as evavinyl ethyl ether.

7) Vinyl ketones, such as vinyl methyl ketone.

8) Vinylamide, such as vinylformamide, vinylacetamide, etc.

9) Aromatic vinyl compounds, such as styrene, vinyltoluene, etc.

10) Heterocyclic vinyl compounds, such as vinylpyridine,
Vinylpyrrolidone etc.

11) Vinylidene halide compound 1, such as vinylidene chloride, vinylidene fluoride, etc.

12) Divinyl compounds, such as divinylbenzene,
butanediol dimethacrylate etc.

13) α-olefins, such as ethylene, propylene, etc.

14) Diolefins such as butadiene, isoprene, etc.

15) Allyl compounds such as allyl acetate, allyl alcohol and diallyl phthalate.

16) Unsaturated basic acids such as acrylic acid and methacrylic acid and their salts, unsaturated dihydrochloric acids such as itaconic acid, fumaric acid and maleic acid, their half esters and their salts, etc.

By combining various types of these monomers, for example, acrylic esters that give a soft polymer, and methacrylic esters and styrene that give a hard polymer, it is possible to change from hard resin to soft resin, from room temperature drying to heat drying. Various types of resins can be obtained.

Preferred ethylenically unsaturated monomers for the present invention include common monomers such as methyl acrylate, acrylic ether, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate. Monomers or monomer mixtures containing monomers as main components are preferred.

More preferable ethylenically unsaturated monomers for the present invention include the above-mentioned monomers or monomer mixtures.
), ie, acrylic acid, methacrylic acid, etc., in a proportion of 0.5 to 15% in the total monomers.
! It is contained in an amount of 1 fit%, particularly preferably 1 to 8%. By neutralizing the monomer obtained using these monomers with a base, a very stable emulsion polymer can be obtained, which is preferable for the present invention. Furthermore, when monomers having carboxyl groups or hydroxyl groups are combined, the corrosion resistance, water resistance, and solvent resistance can be further improved by adding melamine resin, epoxy resin, etc. On the other hand, the amount of the monomer having such a hydrophilic functional group is desirably equal to or less than the amount of 2o3I in all monomers. Furthermore, if a reactive monomer is used, it can be made into a bake-curable resin, and various properties can be achieved.

0 Emulsification Room Method The coating composition of the present invention may be produced by a method similar to a known method. -For example, a reactor is charged with deionized water and an emulsifier. Next, the mixture is degassed with nitrogen gas, and a mixture of monomers is sequentially charged while stirring while heating, and a one-coup reaction is carried out according to a conventional method. Further, the monomer mixture may be emulsified in advance with deionized water and an emulsifier, if necessary. At this time, the monomers may be added all at once, divided, or continuously. As the emulsifier here, ordinary emulsifiers such as anionic, nonionic, cationic, and amphoteric emulsifiers can be used, but the amount should be as small as possible, as using too much will reduce corrosion resistance and water resistance. Preferably, it is used in an amount equivalent to 2% by weight or less of the total monomers.Also, a method of combining without using an ordinary emulsifier is a preferable method, for example, using only a polymerization initiator such as ammonium persulfate. A method of polymerizing a monomer, a method of polymerizing in a water-soluble or water-dispersible polymer resin, etc. can be adopted.As a resin when polymerizing in a water-soluble or water-dispersible polymer resin, Various modified epoxy resins, modified polyolefin resins, copolymers of styrene and maleic acid, copolymers of inbutylene and maleic acid, polyacrylic acid, etc. are used.The preferred method is water-soluble or water-dispersible polymer resins. Preferred methods for particularly improving water resistance and corrosion resistance in the polymerization method include a method using an alkaline aqueous solution of a carboxyl group-containing polyolefin as the polymer resin disclosed in JP-A-57-145102, and a method disclosed in JP-A-57-145102; 60-
As the polymer resin proposed in 253578, there is a method in which the terminal epoxy group of an epoxy resin is esterified with phosphorus-containing alcohol and then neutralized with a base and polymerized in a water-soluble or water-dispersible modified epoxy resin. be able to. According to this emulsion polymerization method, the adverse effects caused by ordinary emulsifiers can be significantly reduced.

Examples of radical-generating catalysts used in the polymerization include hydrogen peroxide, t-butylnohydroberoxide, ammonium persulfate, potassium persulfate, etc., which are diluted with deionized water and added dropwise or all at once. The reaction temperature is preferably 100°C or lower, more preferably 30 to 90°C, and the polymerization is carried out at that temperature for 2 hours or more. In this case, if a reducing agent such as sodium sulfite, ferrous sulfate, or Rongalit is used in combination, the polymerization reaction can proceed smoothly even at low temperatures. After the polymerization is completed, if desired, neutralization is performed with a base to adjust the pH to 5 to 10 to obtain a stable milky white emulsion polymer. At this time, if ammonia water or amine is used, preferably the pH is 6 from the viewpoint of odor.
It is best to adjust it to ~8. The coating composition thus obtained can usually have a solids content of 60 grams or less.

The coating composition of the present invention can be used for corrosion prevention of metals, moisture and water resistance of paper, fibers, wood, slate boards, etc., surface coating of glass and plastics, or various slurries.
It is useful as a binder for pigments, etc.

The coating composition of the present invention may contain crosslinking agents such as urea resins and melamine resins, other water-soluble organic resins such as phenol resins and epoxy resins, and water-dispersible or water-soluble inorganic substances such as colloidal silica. Good, while titanium oxide,
Pigments such as calcium carbonate, general rust preventive pigments, temporary rust preventive agents, inhibitors such as water-soluble chromium compounds, etc. may be added to improve rust prevention properties. Further, thickeners, dispersants, film-forming aids, antifoaming agents, preservatives, freeze stabilizers, organic solvents, etc. may be added.

As a method for coating various articles with the composition of the present invention thus prepared, conventional methods such as brush coating, spray coating, roll coating, and dip coating can be used. Drying after coating is adjusted based on the composition or film thickness, and is usually carried out at a temperature of room temperature to 200° C. and for a time of about 5 seconds to 15 minutes. For example, when a crosslinking agent such as the above-mentioned urea resin or melamine resin is added, the temperature is 100 to 200℃.
Drying and baking hardening are carried out at a temperature of The film thickness is not limited to 49 mm depending on the purpose and use, but when used as a paint, the dry film thickness is usually adjusted to about 0.1 to 20 μm.

Effects> How does the coating composition comprising the emulsion polymer containing the urethane acrylate of the present invention provide the excellent corrosion resistance described herein, as well as solvent resistance, water resistance, etc. It is unclear whether the coating composition can provide an excellent coating film, and as previously described in JP-A-60-1552-76 and JP-A-58-79063,
It is also unclear why urethane acrylate, which has been primarily used as a reactive diluent in resin compositions that are cured by ultraviolet rays or other high-energy rays, can have such an effect.

<Examples> The present invention will be explained in more detail below with reference to Examples and Comparative Examples. Further, parts and parts used below indicate parts by weight and weight % unless otherwise specified.

Example 1 35 parts of bisphenol A diglycidyl ether (epoxy equivalent - Ji250) was dissolved in 15 parts of methyl ethyl ketone, and 3 parts of ortho-IJ phosphoric acid was further mixed with the solution to dissolve 50
The reaction was carried out at 70° C. for 3 hours, and then the temperature was raised to 70° C., and the reaction was continued for a further 7 hours to obtain a phosphoric acid esterified epoxy resin. The epoxy resin has a solid content of 70% and a varnish acid value of 1.
40, and the viscosity was 120 ps. After adding 7 parts of 25 thiammonia water and stirring well, 1183 parts of deionized water was added to this, and while stirring, the pH of the system was further adjusted to 5.0 with 25 thiammonia water to form a phosphoric acid esterified epoxy resin. Dispersed in water.

The above dispersion was transferred to a flask equipped with a stirrer, a cooling tube, and a temperature control device, and the temperature was raised to 65° C. while stirring. Then, while maintaining the temperature at 65°C, a mixed ethylenically unsaturated monomer consisting of 300 parts of ethyl acrylate, 560 parts of ethyl methacrylate, 35 parts of methacrylic acid, and 35 parts of butylcarbamoyloxyethyl acrylate, t-
6.5 parts of butyl hydroperoxide in 53 parts of deionized water
and an aqueous solution of 6.5 parts of Rongalit in 53 parts of deionized water are added dropwise over a period of 6 hours through separate dropping funnels. After the dropwise addition was completed, stirring and heating were continued for 2 hours to complete the reaction, and an emulsion polymer having a pH of 5.0 and a solid content of 35 cm was obtained. Thereafter, the pH of the system was adjusted to 75 with 25% aqueous ammonia to obtain a coating composition.

Example 2 Same method as Example 1, but mixed ethylenically unsaturated monomers were mixed with 50 parts of ethyl acrylate, 50 parts of n-butyl acrylate, 110 parts of styrene, and 31 parts of ethyl methacrylate.
5 parts, 35 parts of methacrylic acid, and 140 parts of butylcarbamoyloxy ethyl acrylate.
An emulsion polymer having a pH of 5.0 and a solid content of 35% was obtained. Thereafter, the pH of the system was adjusted to 75 with 25% aqueous ammonia to obtain a coating composition.

Example 3 The same method as in Production Example 1 was used, but the mixed ethylenically unsaturated monomers were mixed into 50 parts of ethyl acrylate, 150 parts of n-butyl acrylate, 115 parts of methyl methacrylate, 35 parts of acrylic acid, and butylcarbamoyloxy. A mixture consisting of 350 parts of ethyl acrylate was used to obtain an emulsion polymer having a pH of 5.0 and a solid content of 35%. Thereafter, the pH of the system was adjusted to 7.5Ky4 with 25% aqueous ammonia to obtain a coating composition.

Example 4 18,157 parts of Zaixen A (ammonium salt of ethylene/acrylic acid copolymer, manufactured by Seitetsu Kagaku Kogyo ■) and 533 parts of deionized water were placed in a flask equipped with a stirrer, a cooling tube, and a temperature control device, and the mixture was stirred while stirring. The temperature was raised to 65°C. Then, while maintaining the temperature at 65°C, a mixed ethylenically unsaturated monomer consisting of 250 parts of ethyl acrylate, 275 parts of ethyl methacrylate, 35 parts of methacrylic acid, and 140 parts of butylcarbamoyloxyethyl acrylate, t-
6.5 parts of butyl hydroperoxide in 11 parts of deionized water
An aqueous solution of 7 parts of Rongalit in 117 parts of deionized water and an aqueous solution of 3.5 parts of Rongalit in 117 parts of deionized water are each added dropwise over 6 hours using separate dropping funnels. After finishing the dripping, 2
The reaction was completed by continuing stirring and heating for an hour, and the pH was 8.5.
A coating composition containing an emulsion polymer having a solid content of 35 qb was obtained.

Example 5 The same method as in Production Example 4 was used, but the mixed ethylenically unsaturated monomers were mixed with 50 parts of ethyl acrylate, 50 parts of n-butyl acrylate, 110 parts of styrene, and 10 parts of ethyl methacrylate.
5 parts, 35 parts of methacrylic acid, and 350 parts of butylcarbamoyloxy ethyl acrylate,
A coating composition containing an emulsion polymer having a pH of 8.6 and a solids content of 55% was obtained.

Example 6 700 parts of deionized water was placed in a flask equipped with a stirrer, a cooling tube, and a temperature control device, and the temperature was raised to 65% while stirring.
The temperature was raised to ℃. Then, while maintaining the temperature at 65°C, a mixed monomer consisting of 200 parts of ethyl acrylate, 115 parts of ethyl methacrylate, 35 parts of methacrylic acid, and 350 parts of butylcarbamoyloxyethyl acrylate was added to polyoxyethylene, an anionic surfactant. 2 parts of sodium alkyl ether sulfate and 279 parts of deionized water were added, and the monomer emulsion was pre-emulsified in a homomixer.
6.5 parts of butyl hydroperoxide in 15 parts of deionized water
An aqueous solution of 4 parts of Rongalite and 3.5 parts of Rongalit in 154 parts of deionized water are each added dropwise through separate addition funnels over a period of 4 hours.

After completing the dropwise addition, stirring and heating were continued for 2 hours to complete the reaction.
An emulsion polymer having a pH of 5.0 and a solids content of 65 cm was obtained. Thereafter, the pH of the system was adjusted to 7.5 with 25% ammonia water to obtain a coating composition.

Comparative Example 1 The method was the same as in Example 1, but the mixed ethylenically unsaturated monomer was replaced with a mixed solution consisting of 550 parts of n-butyl acrylate, 615 parts of ethyl methacrylate, and 65 parts of methacrylic acid, and P H3 , 5. An emulsion polymer with a solid content of 55% was obtained. After that, the pH of the system was adjusted to 6 with 25 thiammonia water.
．． 5 to obtain a coating composition. In this comparative example, the same polymerization method as in Example 1 was used, and the amount of urethane acrylate in the mixed monomer was below the range of the present invention (0%).

Comparative Example 2 The same method as in Example 1 was used, but mixed ethylenically unsaturated monomers were mixed with 35 parts of n-butyl acrylate and 3 parts of methacrylic acid.
A mixed solution consisting of 5 parts and 630 parts of butylcarbamoyloxy ethyl acrylate was used for polymerization, and gelation occurred after 3 hours. In this comparative example, the amount of urethane acrylate in the mixed monomer was greater than the range of the present invention (90%).
This is the case.

Comparative Example 6 700 parts of deionized water was put into a flask equipped with a stirrer, a cooling tube, and a temperature control device, and the temperature was raised to 65% while stirring.
The temperature was raised to ℃. Then, while maintaining the temperature at 65°C, a mixed monomer consisting of 350 parts of ethyl acrylate, 315 parts of ethyl methacrylate, and 35 parts of methacrylic acid was mixed with 2 parts of sodium polyoxyethylene alkyl ether sulfate, an anionic surfactant, and 273 parts of ionized water was added, and a monomer emulsion pre-emulsified using a homomixer, an aqueous solution of 3.5 parts of t-butyl hydroperoxide dissolved in 154 parts of deionized water, and 3.5 parts of Rongalite were deionized. Aqueous solutions in 154 parts of water are added dropwise over a period of 4 hours using separate addition funnels. After the dropwise addition, stirring and heating were continued for 2 hours to complete the reaction, and the pH was 5.0, solid content was 3.
A 5% emulsion polymer was obtained. Thereafter, the pH of the system was adjusted to 7.5 with 25% ammonia water to obtain a coating composition.

In this comparative example, the same polymerization method as in Example 6 was used, but the amount of urethane acrylate in the mixed monomer was below the range of the present invention (0%).

4th Duke.

The coating compositions obtained in each of the Examples and Comparative Examples were applied to various substrates to form films, and the following experiments were conducted, and the results are shown in Table 1.

1) Corrosion resistance (salt spray test) Using the test plates a) to b) below, JIS-Z-23
A salt spray test was conducted according to No. 71.

The area where red rust occurred was evaluated using a 10-point scale. i.e. 10
A point indicates no occurrence of red rust, and a score of 9 indicates an area of up to 10 inches where red rust has occurred (the same criteria apply hereinafter).

a) A 5PCC plate measuring 150 x 70 x 0.8 wr in thickness was degreased and dried in a conventional manner, the coating composition was applied to the steel material, and the coating composition was dried at 70°C for 10 minutes to prepare a test plate.

The coating film thickness was approximately 10μ.

b) Bonde board of length 150 x width 70 x board thickness 0.8 mm (◆1
44) was degreased and dried in a conventional manner, a coating composition was applied to this steel material, and the coating composition was dried at 70° C. for 10 minutes to obtain a test plate. The coating film thickness was approximately 10μ.

2) A test board was prepared by coating a solvent-resistant bonded board $144 and drying it at 70°C for 10 minutes. The coating film thickness was approximately 10 μm.

The test plate was immersed in ethanol and the state of the membrane was observed.

○...No change Δ...Swelling or slight elution×・
... Elution 3) It was painted on a water-resistant aluminum plate and dried at 70°C for 10 minutes to prepare a test plate. The coating film thickness was approximately 1 μm. The test plate was immersed in water at room temperature for 24 hours, and the state of the film was observed.

O: No change Δ: Slight whitening ×: Whitening or blister As is clear from Table 1, the corrosion resistance of the substrate coated with the composition of the present invention, the solvent resistance of the coating film, and the water resistance It can be seen that both properties are good.

(c) Effects of the invention According to the present invention, it is possible to impart excellent corrosion resistance to various products, and to obtain a coating film having excellent solvent resistance, water resistance, etc. You can choose anything from flexible to hard, and it can be used in a wide range of fields.
The effects brought about by the present invention are immeasurable.

Claims (1)

[Claims] 1. 1 to 80% by weight of the following monomer (A) and the following monomer (B)
) A coating composition comprising an emulsion polymer containing 20 to 99% by weight as a constituent component. Monomer (A) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1 is a hydrogen atom or a methyl group, R_2 is an alkyl group having 1 to 8 carbon atoms, and R_3 is a carbon atom number of 2 to 8.)
4 is an alkylene group. ) Monomer (B) Ethylenically unsaturated monomer copolymerizable with monomer (A)