JPH0619059B2 - Coating material to prevent blocking - Google Patents

Description

TECHNICAL FIELD The present invention relates to a coating material for blocking prevention. More specifically, the present invention relates to a coating agent for antiblocking, which can protect an article to be coated and prevent the blocking phenomenon by applying it to both surfaces of various base materials, and can overcoat various coating materials if necessary.

(Problems to be solved by conventional technologies and inventions) Conventionally, products manufactured in factory lines such as ceramic siding materials and slate roof tiles are coated with various paints in order to enhance the added value and protection function of the products. However, there is a problem that a so-called loose blocking phenomenon occurs, which makes it difficult to peel off when the coated objects are stacked and stored. In order to prevent such a phenomenon, a blocking phenomenon is usually prevented by sandwiching a synthetic paper such as a polyethylene sheet between products. However, such synthetic papers are unnecessary and disposable when used, and they cannot fulfill the purpose other than preventing the blocking phenomenon, that is, the function of protecting the product at all, and there is a great cost problem. . As another method for preventing the blocking phenomenon, a substance that imparts releasability to the coating film, for example, a treatment agent obtained by adding a polyethylene wax emulsion, colloidal sili, or the like alone or to another water-based resin is used. There is a method of coating the base material in advance. The use of such a substance imparting releasability can sufficiently achieve the purpose in preventing the blocking phenomenon, but the durability of the coating film itself is inferior, so that the object to be coated is protected for a long time. Difficult to do. In addition, the adhesion to other paints and adhesives is poor, and there is the disadvantage that the paintability when overcoating various paints on the object to be coated deteriorates, and the adhesive strength when bonding the object to the structure decreases. It was As a method of preventing the blocking phenomenon, it is effective to form a harder polymer coating on the substrate, but if an ordinary emulsion resin is used, sufficient film forming ability is obtained if sufficient blocking resistance is obtained. However, there is a problem in that On the contrary, the use of a film forming auxiliary agent or the like for this improvement lowers the blocking resistance or increases the change with time of the film.

(Technical Means for Solving Problems) As a result of intensive studies conducted by the present inventors in view of such a current situation, as a result of using an emulsion resin having a specific composition and a specific structure as a coating agent, They found that the problems could be solved all at once, and completed the present invention.

That is, in the present invention, the total amount of the polymerizable monomer component used is 0.1 to 10% by weight of the polymerizable monomer (a) containing a carboxyl group in the molecule and other polymerizable monomers. (B) 90 to 99.9% by weight (however, (a) + (b) is 100% by weight.)
Which is a multi-stage polymerization copolymer obtained by dividing the polymerizable monomer component into multi-stage emulsion polymerization, and the Tg of the polymer component in the first stage is 30 ° C. or higher, The present invention relates to a coating material for blocking prevention, which has a Tg of 20 ° C. or less as a polymer component.

The polymerizable monomer (a) containing a carboxyl group in the molecule (hereinafter referred to as the monomer (a)) used in the present invention is particularly preferably a polymerizable monomer having a carboxyl group in the molecule. Without limitation, for example (meth) acrylic acid,
Unsaturated carboxylic acids such as crotonic acid, itaconic acid, fumaric acid, maleic acid, monomethyl fumarate, monoethyl fumarate, monomethyl maleate and monoethyl maleate or derivatives thereof may be mentioned. One of these or Two or more kinds can be used. The total amount of the polymerizable monomer (a) used in the present invention is in the range of 0.1 to 10% by weight based on the total polymerizable monomer components. If the amount of the monomer (a) used is less than 0.1% by weight, the stability at the time of multi-stage emulsion polymerization will be reduced and the adhesion to various base materials will be reduced.
If the amount is more than 0% by weight, the water resistance of the resulting coating film is lowered, which is not preferable.

Other polymerizable monomer (b) used in the present invention
(Hereinafter, referred to as the monomer (b)) is the monomer (a)
It is not particularly limited as long as it is a monomer copolymerizable with, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate and the like. (Meth) acrylic acid esters; aromatic unsaturated monomers such as styrene, α-chlorostyrene, vinyltoluene; vinyl halides such as vinyl fluoride and vinyl chloride; unsaturated cyanides such as (meth) acrylonitrile Compounds; vinyl esters such as vinyl acetate and vinyl propionate; hydroxyl group-containing unsaturated monomers such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; (meth) acrylamide, N-methylol (meth ) Unsaturated acid such as acrylamide Or its derivatives; amino group-containing unsaturated monomers such as dimethylaminoethyl (meth) acrylate; polyfunctional unsaturated monomers such as divinylbenzene, ethylene glycol di (meth) acrylate;
Glycidyl group-containing unsaturated monomers such as glycidyl (meth) acrylate and allyl glycidyl ether; N-phenylmaleimide, N-chlorophenylmaleimide, N-
Monomaleimides such as cyclohexylmaleimide;
Examples thereof include bismaleimides such as N, N′-diphenylmethane-4,4′-bismaleimide, and one or more of these can be used. The monomer (b) is used in the range of 90 to 99.9% by weight based on the total polymerizable monomer components. Further, in the present invention, it is desirable that 30% by weight or more of the monomer (b) is a (meth) acrylic acid ester from the viewpoint of weather resistance.

In the coating agent for preventing blocking of the present invention, the total amount of the polymerizable monomer component used is 0.1 to 10% by weight of the polymerizable monomer (a) containing a carboxyl group in the molecule and other 90 to 99.9% by weight of the polymerizable monomer (b) (however,
(A) + (b) is 100% by weight. ) Is obtained by emulsion-polymerizing the polymerizable monomer component which is) in multiple stages, in which case the Tg of the first stage polymer component is 30 ° C. or higher, preferably 45 ° C. or higher, It is necessary that the Tg of the polymer component in the last stage is 20 ° C. or lower, preferably 0 ° C. or lower.

The Tg in the present invention means a value analyzed by DTA (differential thermal analysis). The term "multistage emulsion polymerization" as used herein means that some components are first selected from the polymerizable monomer components so that the Tg of the polymer is 30 ° C. or higher, and the partial components are used in the first stage. The emulsion polymerization is carried out by a known emulsion polymerization method, and in the presence of the obtained polymer component, the remaining monomer components are used to successively carry out the emulsion polymerization of the second and subsequent steps. At this time, after the second step, the remaining monomer components used in the first step may be used in the whole amount for two-step polymerization, or may be appropriately divided into three or more steps for polymerization. Then, the Tg of the polymer component may be set to 20 ° C. or lower at the last stage. As the multi-stage emulsion polymerization, usually two to three stages of polymerization are used. Even if the polymerization is carried out in more stages than this, no particular improvement in the performance can be expected, and it only causes complication during the production. The coating agent for blocking prevention of the present invention,
The Tg of each of the first-stage polymer component and the last-stage polymer component needs to be as defined above. First
When the Tg of the polymer component in the first stage is 30 ° C. or less, the blocking resistance is not expressed, and when the Tg of the polymer component in the last stage is 20 ° C. or more, the film-forming property of the coating material using this Is lowered, and a film-forming aid is required at the time of forming a coating film, and a high temperature is required for drying, which is not preferable. Further, in obtaining a coating agent for blocking prevention, the polymer component in the first stage is preferably contained in the copolymer in an amount of 20 to 90% by weight, more preferably 35 to 70% by weight, and the final stage. The polymer component can be used in the copolymer in an amount of preferably 10 to 80% by weight, more preferably 30 to 65% by weight. By setting the amounts of the first-stage polymer component and the last-stage polymer component within this range, both the blocking resistance and the film-forming property of the coating film can be compatible at a high level, and the durability can be improved. It is possible to obtain a coating agent for preventing blocking, which has markedly improved coating performance including the above.

In the present invention, examples of the polymerization initiator used in the multi-stage emulsion polymerization include known water-soluble or oil-soluble initiators such as ammonium persulfate, potassium persulfate, hydrogen peroxide, and butyl hydroperoxide. At this time, a redox initiator may be used by using sodium bisulfite, L-ascorbic acid or the like as a reducing agent. As the emulsifier, an anionic activator such as sodium lauryl sulfate and a nonionic activator such as polyoxyethylene alkyl ether are used, but in some cases, the polymerization can be performed in the absence of the emulsifier. In the present invention, a chain transfer agent such as laurylmethylmecaptan may be used for the purpose of controlling the molecular weight during the polymerization. The coating composition for blocking prevention of the present invention polymerized according to the above procedure may be neutralized with a basic compound, if necessary. Examples of the basic compound that can be used include ammonia, triethylamine, morpholine, sodium hydroxide and the like.

Further, if necessary, known additives such as film-forming aids, pigments, fillers, toners, wetting agents, antistatic agents, etc. may be blended with the anti-blocking coating material of the present invention.

(Effect of the invention) The coating material for blocking prevention of the present invention is a multi-stage polymerization copolymer having a Tg of the first stage polymer component of 30 ° C or higher and a Tg of the last stage polymer component of 20 ° C or lower. Since they are united, a coating film having a high degree of blocking resistance and a sufficient film-forming property and having little change with time after film-forming can be obtained. Furthermore the first
By adjusting the amounts of the polymer component in the last stage and the polymer component in the last stage to be in the specific ranges, the coating performance including durability is remarkably improved. Therefore, the article coated with the coating material for blocking prevention of the present invention can maintain the state immediately after coating for a long period of time. Further, since the coating material for preventing blocking of the present invention is excellent in overcoating suitability of various paints, it is possible to coat the coating material on one surface by coating the coating material on both surfaces of various substrates in advance. It can be applied easily, and can prevent the blocking phenomenon when the coated objects are stacked after application. That is, by applying a coating material on the anti-blocking coating material of the present invention, because the coating film coating surface is reinforced and in contact with the anti-blocking coating material on the opposite surface,
It becomes possible to exhibit a good blocking prevention ability. It is also possible to improve the anti-blocking ability of the paint film by adding the anti-blocking paint material of the present invention to the paint. Therefore, the coating material for preventing blocking of the present invention can be used very effectively for substrates such as inorganic building materials, metals, papers, plastics, and woods.

(Examples) The present invention is described in detail below with reference to examples, but the present invention is not limited to the following examples. The parts in the examples are by weight unless otherwise specified.

Further, in the examples, the glass transition temperature Tg was measured by DTA (differential thermal analysis) of a polymer obtained by copolymerizing each stage. (Apparatus: Shimadzu Thermal Analyzer D
T-40) Example 1 1 equipped with a stirrer, reflux condenser, dropping funnel, thermometer
After deionized water (500 parts) and sodium lauryl sulfate (8 parts) were charged in the separable flask (1), the temperature was raised to 70 ° C. with stirring while blowing nitrogen gas. Then, the polymerizable monomer mixture (A) (glass transition temperature 60 ° C.) consisting of 80 parts of methyl methacrylate, 80 parts of styrene, 36 parts of butyl acrylate and 4 parts of methacrylic acid was used as the first step.
It was dripped uniformly over time. At the same time, 10 parts of a 10% ammonium persulfate aqueous solution was uniformly added dropwise over 1 hour. After aging for 1 hour, the polymerizable monomer mixture (B) (glass transition temperature -8 ° C) consisting of 80 parts of methyl methacrylate, 116 parts of butyl acrylate and 4 parts of methacrylic acid was used as the final stage for 1 hour. It was dripped uniformly over. At the same time, 10 parts of a 10% ammonium persulfate aqueous solution was uniformly added dropwise over 1 hour. After that, aging was carried out for 1 hour. After cooling, 6.3 parts of 25% ammonium water was added to neutralize. The coating material (1) thus obtained had a nonvolatile content of 43.5% and PH9.
0, viscosity 95 cps (B-type viscometer, No. 1 rotor, 30 rpm, 25 ° C.), and a minimum film forming temperature of 25 ° C. To 100 parts of the obtained coating material (1), 3 parts of a film-forming auxiliary CS-12 (manufactured by Chisso Corporation) was added, and the mixture was well stirred to make it uniform. Coating material containing this film-forming aid
After spraying 100g / cm ^{2 of} (1) on both sides of two flexible boards by spraying, and then drying in a hot air dryer at 100 ° C for 5 minutes (wind speed 1m / S), paint on one side with the following composition (1) Was spray-applied at 200 g / cm ² and dried in a hot air dryer at 100 ° C. for 5 minutes (air velocity 1 m / S).

When the surface temperature of the article thus obtained reaches 70 ° C., the coating surface of the coating material (1) and the coating surface of the coating material (1) are superposed, and a pressure of 5 kg / cm ² is applied by a press. Was added at 70 ° C. for 30 minutes.

The two flexible boards pressed in this way were peeled off resistancelessly after the completion of pressing, and the painted surface was not damaged at all. Further, the coating film performance test results of the test pieces coated under the same conditions as used in the above test are as shown in Table 1.

Example 2 After charging 500 parts of deionized water into the same separable flask as used in Example 1, while blowing nitrogen gas,
The temperature was raised to 75 ° C. with stirring. Then 120 parts of styrene and 20 of acrylonitrile that had been adjusted beforehand.
Part, ethyl acrylate 58 parts, itaconic acid 2 parts (glass transition temperature of the above polymerized monomer mixture 53 ° C.), Rebenol WZ (manufactured by Kao Corporation, 6 parts of 25% aqueous solution of sodium polyoxyethylene nonylphenyl ether sulfate) , 25
% Aqueous solution of Nonipol 200 (polyoxyethylene nonylphenyl ether manufactured by Sanyo Kasei Co., Ltd.) 4 parts, ammonium persulfate 1 part, and deionized water 69 parts as a first stage pre-emulsion mixture (C) as a first stage and uniform for 1 hour Was added dropwise. During this period, 5 parts of a 10% aqueous sodium hydrogen sulfite solution was added evenly every 10 minutes. After aging for 1 hour, 64 parts of styrene, 35 parts of butyl acrylate, 1 part of acrylic acid (glass transition temperature of the above polymerizable monomer mixture: 25 ° C.), 3 parts of rebenol WZ, 25
% Aqueous solution Nonipol 200 (2 parts), ammonium persulfate (0.5 parts), and deionized water (34.5 parts) as a second stage, a pre-emulsion mixture (D) was uniformly added dropwise over 30 minutes. During this period, 2.5 parts of 10% sodium bisulfite was added evenly every 10 minutes. Then 30
After aging for 50 minutes, 50 parts of styrene, 48 parts of 2-ethylhexyl acrylate, 2 parts of methacrylic acid (glass transition temperature of the above polymerizable monomer mixture-7 ° C), 3 parts of rebenol WZ, 25% aqueous solution of nonipol 200. Two
Parts, 0.5 parts ammonium persulfate, 34.5 deionized water
The pre-emulsion mixture (E) consisting of 10 parts was uniformly added dropwise over 30 minutes as the last step. During this period, 2.5 parts of a 10% aqueous sodium hydrogen sulfite solution was evenly added every 10 minutes. Then 60
Aged for minutes. After cooling, 6 parts of 25% aqueous ammonia was added for neutralization. Coating material thus obtained
(2) is non-volatile content 42.2%, pH 9.0, viscosity 250c
ps (B type viscometer, No. 2 rotor, 30 rpm, 2
5 ° C) and the minimum film forming temperature of 23 ° C.

Using this coating material (2), a blocking phenomenon prevention test was conducted in the same manner as in Example 1. As a result, the two flexible boards peeled off without resistance after the completion of pressurization, and the coated surface was not damaged at all. It was The results of the coating film performance test were as shown in Table 1.

Comparative Example 1 In Example 1, in the first stage, the polymerized monomer mixture (B) was used.
Further, the same operation as in Example 1 was repeated except that the polymerizable monomer mixture (A) was used in the last stage to obtain a coating film material for comparison (1). The characteristic values of the obtained comparative coating material (1) were a non-volatile content of 43.3%, a pH of 9.0, a viscosity of 110 cps, and a minimum film-forming temperature of 55 ° C. To 100 parts of this comparative coating material (1), 8 parts of CS-12 was added and well stirred to homogenize. A blocking piece prevention test and a coating film performance test were conducted using a test piece coated with the same method as in Example 1. As a result of the blocking phenomenon prevention test, a blocking phenomenon occurred and the two coated plates could not be separated.
The results of the coating film performance test were as shown in Table 1.

Comparative Example 2 In Example 2, only the pre-emulsion mixture (C) used in the first stage without performing the second-stage and last-stage polymerizations of the pre-emulsion mixture with (D) and (E) (this At this time, the same operation as in Example 2 was repeated except that the polymerization of Example 2) was performed to obtain a comparative coating material (2).

The coating film material for comparison (2) had a non-volatile content of 42.3%, a pH of 9.0, a viscosity of 180 cps, and a minimum film forming temperature of 83 ° C. Since this comparative coating material (2) was not formed as it was, 6 parts of the film-forming aid CS-12 was added to 100 parts of the comparative coating material (2), and the mixture was stirred well to obtain a uniform mixture. As a result of carrying out a blocking phenomenon prevention test in the same manner as in Example 2 using the above-mentioned one, it was found that the coating on the object to be peeled off due to the blocking phenomenon was significantly damaged. Also,
The coating film performance test results were as shown in Table 1.

Comparative Example 3 The coating material (1) was spray-applied at 200 g / cm ^{2 on} one surface of each of the two flexible boards on which the coating material was not applied, and the coating was performed in a hot air dryer at 100 ° C. for 5 minutes (air velocity 1 m /
S) dried.

When the surface temperature of the coated article thus obtained reached 70 ° C., the polyethylene sheet was sandwiched between the coating surface (1) and the back surface of the coating material (1), and the pressure of 5 kg / cm ² was applied by a press. Added at 70 ° C. for 30 minutes.

The two flexible boards and the polyethylene sheet thus pressed had some resistance when peeled off after the completion of pressing, but no particular damage was observed on the coating surface. However, as shown in Table 1, the coating film performance results were inferior to those obtained when the coating material of the present invention was previously coated.

Comparative Example 4 A commercially available self-emulsifying polyethylene wax emulsion (25% aqueous solution) was applied to one surface of each of two flexible boards by spraying at 100 g / cm ² and then heated in a hot air dryer at 100 ° C. for 5 minutes (air speed 1 m / S) After drying, the coating (1) was applied on the opposite surface by spraying at 200 g / cm ² and dried in a hot air dryer at 100 ° C. for 5 minutes (air velocity 1 m / S).

When the surface temperature of the article thus obtained reaches 70 ° C, the coating film of the polyethylene wax emulsion and the coating film surface of the paint (1) are superposed, and a pressure of 5 kg / cm ² is applied at 70 ° C with a press. Added 30 minutes.

The two flexible boards pressed in this way were peeled off resistancelessly after the completion of pressing, but several pieces of the polyethylene wax emulsion coating film adhered to the coated surface. Further, the coating film performance was inferior to that using the coating material of the present invention as shown in Table 1.

Claims (2)

[Claims] 1. The total amount of the polymerizable monomer component used is a polymerizable monomer (a) containing a carboxyl group in the molecule.
0.1-10% by weight and other polymerizable monomer (b) 9
A multistage polymerization copolymer obtained by emulsion-polymerizing a polymerizable monomer component of 0 to 99.9% by weight (however, (a) + (b) is 100% by weight) in multiple stages. And a Tg of the polymer component of the first stage is 30 ° C. or higher, and a Tg of the polymer component of the last stage is 20 ° C. or lower, an anti-blocking coating material. 2. A multistage polymerization copolymer wherein the first stage polymer component is 20 to 90% by weight and the last stage polymer component is 10 to 10% by weight.
The coating material for blocking prevention according to claim 1, which has a ratio in the range of 80% by weight.