JPH0751691B2 - Aqueous liquid for primer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention increases the strength of the surface of a base material by applying it to a porous alkaline inorganic base material such as concrete, mortar, slate plate, and the like, and The present invention relates to an aqueous liquid for a primer that improves paintability and adhesion to a coating material or other finishing material.

[Conventional technology]

Cement-based inorganic building materials, such as concrete, mortar, and slate boards, have a fragile surface layer, and for the purpose of reinforcing the surface fragile layer and improving the adhesion and adhesion to the coating film during surface coating, The application is being done. As this type of primer solution, a solvent-type primer in which a synthetic resin is dissolved in an organic solvent has been conventionally used. Such a solvent-type primer has excellent penetrability into a base material, and also has an effect of reinforcing a surface fragile layer and improving an adhesive force and an adhesive force with respect to a coating film and the like.
However, the amount of solvent in the primer is as large as 50 to 90% by weight (hereinafter abbreviated as “%”), and all such solvents are wasted because they evaporate, resulting in problems in terms of economy and resource saving. is there. Also, since a large amount of solvent is evaporated,
There are also problems in terms of safety and pollution. Therefore, there is a demand for the development of an aqueous primer that does not have the above problems in place of such a solvent-type primer. There are three types of water-based primers that meet such demands, such as a primer using polymer latex such as rubber, a two-component reaction type emulsion primer such as epoxy resin emulsion and a water-soluble resin primer such as modified polyvinyl alcohol. Water-based primers have been developed and are available on the market. However, the primer using the above-mentioned polymer latex has a problem that its permeability is poor due to its high viscosity and, as a result, the reinforcing effect on the surface layer of the substrate becomes insufficient. Also,
The two-component reactive emulsion primer such as the epoxy resin emulsion is improved in the permeability to the base material as compared with the polymer latex described above by a method such as emulsifying a liquid resin or a resin solution, and exhibits excellent performance. It has already been put to practical use. However, since this emulsion is a two-component type, there is a problem in that the operation and handling such as the two-component mixing operation and the management of the pot life after the two-component mixing are complicated and a problem due to it is likely to occur. Further, the water-soluble resin primer has the same excellent performance as the solvent-type primer in terms of penetrability into the substrate, but it has poor durability because of poor water resistance and alkali resistance of the film. However, there is a big problem in putting this to practical use.

[Problems to be solved by the invention]

As described above, the three types of water-based primers have all advantages and disadvantages, and in reality, no water-based primer having satisfactory performance exists.

The present invention has been made in view of such circumstances, and provides a water-based primer which is excellent in resource saving, safety and hygiene, is non-polluting, and has good base material permeability, reinforcing effect, workability, and the like. To that end.

[Means for solving problems]

In order to achieve the above object, an aqueous solution for a primer of the present invention is prepared by adding the following component (A) and (B) to an aqueous medium.
The components are contained at a ratio of (A) / (B) = 90/10 to 100/0 on a weight basis.

(A) A chain polymer which is soluble in the above aqueous medium and contains at least 0.3 mol% of a structural unit represented by the following formula (I) in the molecular structure.

(B) A polymer insoluble in the aqueous medium.

That is, the present inventors have conducted a series of studies centered on acrylic acid-based resins in order to find a water-soluble resin capable of forming a film excellent in water resistance and the like, and as a result, are represented by the general formula (I). A chain polymer containing a specific amount of structural units dissolves well in water, and the aqueous solution penetrates well into the surface layer of the cement-based substrate to form a film structure with excellent water resistance and alkali resistance. The inventors have found that the strength of the surface layer is increased, and the surface layer thereof improves the adhesion to the coating film of the topcoat paint or the adhesive layer to firmly adhere the layer.

As described above, the aqueous solution for a primer of the present invention brings high strength to the surface layer of the cement-based substrate,
The constituent unit of the general formula (I) present in the molecular structure of the chain polymer as the component (A) is activated by the alkali in the cement-based base material, and a crosslinking phenomenon occurs between the chain polymers. It is considered that this is caused by the formation of a three-dimensional network structure film. That is, the coating enhances the strength of the surface layer of the cement-based substrate, and the coating is extremely rich in water resistance and alkali resistance. In addition, the three-dimensional network structure film has a constitutional unit having a cationic property as represented by the general formula (I), and is applied to the surface of the cement-based substrate by this cationic property. It is considered that it has the effect of improving the adhesion and adhesiveness with the topcoat paint and adhesive.

The aqueous primer liquid of the present invention is obtained by using an aqueous medium and the above-mentioned components (A) and (B).

Most preferably, water is used as the aqueous medium. However, an organic solvent may be used in combination in order to increase the solubility of the component (A) or to increase the permeability of a cement-based substrate or the like. As the organic solvent, one having a high solubility in water is appropriately used. As such an organic solvent, methanol, ethanol, propanol, acetone, methyl ethyl ketone, dioxane, ethylene glycol, propylene glycol, glycerin, methyl carbitol, ethyl carbitol, butyl carbitol, methyl cellosolve, ethyl cellosolve, acetic acid and the above alcohol, carb Examples include acetic acid esters of tall and cellosolve. Such an organic solvent is used in a proportion of 50% or less, preferably 20% or less of the total amount of the aqueous medium from the viewpoint of safety, hygiene and the like of the aqueous solution for primer of the present invention. In addition, the above-mentioned aqueous medium contains (A) component,
The component (B) is contained, and it is desirable to adjust the pH to 7 or less from the viewpoint of preventing gelation of these components during storage. For adjusting the pH, inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid and organic acids such as formic acid, acetic acid and oxalic acid are used.

The component (A) contained in the aqueous medium is a chain polymer which is soluble in the aqueous medium and contains at least 0.3 mol% of the structural unit represented by the general formula (I) in the molecular structure. is there. It is necessary that the component (A) contains 0.3 mol% or more of the structural unit represented by the general formula (I) in its molecular structure. That is, the presence of the constitutional unit represented by the general formula (I) causes the aqueous solution for a primer of the present invention to exert the excellent effects as described above, and for that purpose, at least the general formula (I ) It is necessary that the content of the structural unit represented by 3) is 0.3 mol% or more. Such a chain polymer of the component (A) has the following general formula (I ′) Or a cationic alkali crosslinkable monomer represented by the formula (in this case, in the chain polymer, the constitutional unit represented by the general formula (I) is 100 mol%), or This is obtained by copolymerizing 0.3 mol% or more with another olefinic unsaturated monomer (hereinafter abbreviated as "other monomer") in a ratio of up to 99.7 mol%.

Typical examples of the cationic alkali crosslinkable monomer represented by the general formula (I ′) include, for example, a halogenated salt of dimethylaminomethylacryl (or methacryl) amide epichlorohydrin adduct, dimethylaminoethylacryl ( Or methacryl) amido epichlorohydrin adduct halogenated salt, dimethylaminopropylacryl (or methacryl) amido epichlorohydrin adduct halogenated salt and alkyl sulfonate, dimethylaminomethyl acryl (or methacryl) ester epichlorohydrin adduct halogenated salt , Dimethylaminoethyl acrylic (or methacrylic) ester epichlorohydrin adduct halogenated salt, dimethylaminopropyl acrylic (or methacrylic) ester epichlorohydrin Object of halide salts, dimethylaminopropyl acrylate (or methacrylic) ester epichlorohydrin adducts alkyl sulfonates and their corresponding epoxides pair [Formula 'in, R (I)' is The compound which is

Further, as the other monomer copolymerized with the above-mentioned cationic alkali cross-linking monomer as required, for example, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, alkoxymethyl acrylamide and alkoxymethyl methacrylamides , Acrylic acid,
Methyl esters, ethyl esters, propyl esters, butyl esters, 2-ethylhexyl esters, hydroxyethyl esters, hydroxypropyl esters, glycidyl esters, 1-chloro-2-hydroxypropyl esters of methacrylic acid and these polymerizable unsaturated acids, various Examples include various esters such as amino alcohol esters, vinyl acetates such as vinyl acetate and vinyl propionate, styrene and vinyl chloride.

The chain polymer of the component (A) obtained by polymerizing only the cationic alkali crosslinkable monomer represented by the general formula (I ') is soluble in an aqueous medium. However, when the above cationic alkali crosslinkable monomer and another monomer are copolymerized, the resulting polymer may have poor solubility in an aqueous medium depending on its copolymerization composition. is there.
Therefore, in the case of copolymerizing the above-mentioned cationic alkali cross-linking type monomer with other monomers, a copolymerizable composition (monomer amount) so that the resulting polymer is soluble in an aqueous medium. It is important to select body type and copolymerization ratio).
Such determination of the copolymer composition can be easily performed experimentally.

In the present invention, “soluble in an aqueous medium” means substantially unlimited in an aqueous medium, in other words, it is free without any limitation within the concentration range of a usual polymer in the aqueous solution for a primer of the present invention. It means that it can be dissolved in.
Therefore, the chain polymer as the component (A) used in the present invention is required to have the above characteristics. However, as a result of the copolymerization with other monomers, the polymer does not have the solubility in the above meaning in an aqueous medium and shows a moderate solubility (for example, having a solubility of about 20%). It is difficult to say that it is soluble in an aqueous medium. However, such a polymer cannot be used in the present invention, and a portion of the above-mentioned polymer which can be dissolved in an aqueous medium is used as the chain polymer (A) component of the present invention, and is not dissolved. It can be used by considering a part as a part or all of the insoluble polymer (B).

In the aqueous liquid for a primer of the present invention, the insoluble polymer as the component (B) that constitutes the polymer component together with the chain polymer as the component (A) is usually an olefinic unsaturated monomer used in emulsion polymerization. An emulsion polymer obtained by emulsion-polymerizing a body alone or two or more kinds is used. However, the insoluble polymer is not limited to this, and any insoluble polymer can be used as long as it has at least the same level of water resistance as the emulsion polymer. This insoluble polymer mainly remains on the surface of the base material when the aqueous liquid for a primer of the present invention is applied to the base material and the like, and together with the chain polymer of the component (A), the base material for cement and the coating material. , It exerts the effect of improving the adhesion and adhesiveness with adhesives and the like.

Examples of the olefinic unsaturated monomer for emulsion polymerization used in the production of the insoluble polymer as the component (B) include vinyl acetate, acrylic acid alkyl esters, methacrylic acid alkyl esters, styrene, acrylonitrile, One or more hydrophobic monomers such as methacrylonitrile may be used. In addition, these hydrophobic monomers, acrylic acid, methacrylic acid, amides of acrylic acid or methacrylic acid, methylolated amides, alkoxymethylated amides or alkylaminoesters, the cationic of the general formula (I) Examples thereof include a mixture with an alkali-crosslinking type monomer, a monochlorovinyl acetate, and a hydrophilic monomer such as 1-chloro-2-hydroxypropyl acrylate. Needless to say, the latter hydrophilic monomer is used in such an amount and composition that the produced polymer is not soluble in the aqueous medium.

Further, it is important that the insoluble polymer as the component (B) forms a film sufficiently under the conditions of use in order for it to exhibit the primer performance together with the chain polymer as the component (A).
Therefore, when using a polymer with a high Tg (glass transition temperature) that does not form a film under the conditions of use, use a plasticizer such as dibutyl phthalate or dioctyl phthalate, or a film forming aid such as butyl cellosolve or butyl carbitol acetate. It is desirable to use them together.

In the case of the insoluble polymer as the component (B), unlike the chain polymer as the component (A), the copolymerization of the cationic alkali crosslinkable monomer represented by the general formula (I ′) does not always need to be performed. However, from the viewpoints of miscibility with the chain polymer and performance of the formed film, it is preferable to copolymerize the above monomer.

Such an insoluble polymer as the component (B) is generally blended in the form of emulsion. In this way, by blending in the emulsion form, more uniform mixing with the chain polymer of the component (A) is possible, and an aqueous primer liquid having excellent homogeneity can be obtained.

The aqueous solution for a primer of the present invention contains the chain polymer of the component (A) and the insoluble polymer of the component (B) in a weight ratio of (A) / (B) = 90/10 to 100-0. Contained in. That is, when the ratio of the chain polymer to the total polymer in the aqueous liquid for a primer is less than 10%, the primer (or schiller) is applied to the extent that it is conventionally used for cement-based inorganic building materials (resin concentration 5 to 5). 30% of primer 10
This is because the effect of reinforcing the base material and improving the adhesive strength is small even if 0 to 200 g / m ^{2 is} applied. Temporarily increase the amount of coating to increase the proportion of primer aqueous solution applied per unit area,
Therefore, even if the ratio of the chain polymer (component A) per unit area is increased, the effect of reinforcing the base material and improving the adhesive strength is not so high. The reason for this is not clear, but when the proportion of the chain polymer (component A) in the total polymer is low, the influence of the balance of the insoluble polymer (component B), especially the insoluble polymer in the emulsion dispersion state ( It is considered that the chain polymer (A component) is adsorbed by the (B component particles) and the actual concentration is lower than the theoretical concentration of the chain polymer in the primer aqueous solution.

The aqueous solution for a primer of the present invention contains the above-mentioned components (A) and (B) in the above proportions, but in that case, the total content of the components (A) and (B) is 5 to 5. It is preferable to set the content within the range of 30% and the content of the component (A) to 4% or more from the viewpoint of the effect or workability.

The aqueous primer liquid of the present invention can be produced, for example, by the following three types of methods.

The first method is a method for producing an aqueous primer liquid containing only the chain polymer of the component (A). That is, water or a mixture with a water-miscible organic solvent such as methanol, ethanol, propanol, or acetone is used as a polymerization medium,
In this medium, the cationic alkali crosslinkable monomer represented by the general formula (I ′) (one kind or two or more kinds may be used in combination) or the above cationic alkali crosslinkable monomer is used. Add a mixture of the body and other monomers. Next, a polymerization initiator such as benzoyl peroxide, azobisisobutyronitrile, 2,2′-azobisamidinopropane hydrochloride, ammonium persulfate, etc. was added thereto to maintain the system in an acidic state. According to the method, a nitrogen gas atmosphere is obtained, and in that state, the mixture is heated and stirred at 60 to 90 ° C. for 1 to 10 hours to cause polymerization. After that, it is produced by diluting with water or a water-miscible organic solvent, if necessary.

The second method is a method for producing an aqueous liquid for a primer containing both the chain polymer as the component (A) and the insoluble polymer as the component (B). That is, after preparing an aqueous solution for a primer containing only the chain polymer of the component (A) in the same manner as in the first method, a polymerization initiator is added to this aqueous solution, if necessary, and the insoluble polymer is added. The monomer for coalescing is added dropwise in a state of being emulsified with an emulsifier (one or both of nonionic and cationic) while stirring at 60 to 70 ° C. for 3 to 5 hours while stirring. To do. Next, it is a method of producing by continuing heating and stirring at a temperature of 60 to 70 ° C. for 2 to 4 hours to complete the emulsion polymerization reaction. In this case, a cationic alkaline cross-linking type capable of forming a chain polymer (component A) according to the first method after emulsifying a monomer for forming an insoluble polymer with an emulsifier to complete the emulsion polymerization reaction. It is also possible to produce it by heating and stirring and polymerizing a monomer and the like. In this case,
The operation is performed in the reverse order of the method described above.

In the third method, the water-soluble liquid of the chain polymer of the component (A) and the emulsion of the insoluble polymer of the component (B) are used.
And the second method, which is separately prepared, and they are appropriately mixed to produce. According to this method, there is an advantage that the ratio of the chain polymer as the component (A) and the insoluble polymer as the component (B) can be easily changed.

In the first to third methods, the polymerization reaction is carried out in an aqueous medium, but it is necessary to select and use an aqueous medium which does not inhibit the polymerization reaction. Further, by adjusting the pH of the aqueous medium to 7 or less, gelation can be favorably prevented during the polymerization of the chain polymer (component A) and the like. Therefore, adjusting the pH of the aqueous medium to 7 or less is important not only from the viewpoint of gelation prevention during storage but also from the viewpoint of gelation prevention during polymerization.

If necessary, various additives such as pigments, colorants, defoaming agents or conventionally known film-forming aids are added to the primer aqueous solution of the present invention obtained by the above method. But it doesn't matter.

When such an aqueous solution for a primer is used as a primer for a cement-based base material such as concrete, mortar or slate plate, the chain polymer of the component (A) in the aqueous solution penetrates into the permeated water together with water. It quickly penetrates into the surface layer of the base material in a dissolved state, and is crosslinked and cured by the alkali component in the base material to form a polymer film having a three-dimensional network structure excellent in water resistance and alkali resistance. As a result, similarly to the case of using the solvent-based primer, the brittle layer on the surface of the base material is reinforced with robustness and durability. Moreover, since the aqueous liquid for a primer of the present invention is not a solvent system but an aqueous system, it is excellent in safety, hygiene and pollution prevention as compared with a solvent system, and is extremely practical. Moreover, after the application of the aqueous primer liquid of the present invention, the surface of the substrate is overcoated due to the cationic property of the structural unit represented by the general formula (I) in the chain polymer of the component (A). It becomes excellent in affinity and adhesion to paints, adhesives, etc., and also has an effect that these surface finishing layers can be firmly formed.

〔The invention's effect〕

The aqueous solution for a primer of the present invention contains the chain polymer (component A) having the above-described special structure, which makes it possible to obtain an excellent substrate surface similar to that of a solvent type primer while being an aqueous primer. It has a reinforcing effect, and also has an affinity for top coatings and adhesives that are not found in solvent-based primers, etc., and it is possible to firmly form these finishing agent layers on the surface of the cement-based base. become.

Next, the present invention will be described in detail based on examples.

Example 1 A four-necked flask equipped with a stirring blade, a thermometer and a reflux condenser was charged with water, isopropanol and a monomer having the composition shown in Table 1, and then adjusted to pH 4 with acetic acid.
The ratio of water and isopropanol is 7.8: 1 (weight ratio).
And an amount such that the solid content concentration of the reaction system was about 10%.

Next, after heating the reaction solution to 60 ° C, the reaction initiator V50
[Main component: 2,2'-azobis (2-amidinopropane) hydrochloride, manufactured by Otsuka Pharmaceutical Co., Ltd.] 1 part by weight (hereinafter abbreviated as "part") was added, and polymerization reaction was carried out at 65 to 70 ° C for 3 hours with stirring. I went. The obtained primer aqueous solutions were all homogeneous solutions, the polymer concentration was about 10%, and the viscosity was 100-2.
It was 00 cps (30 ° C, BM type viscometer) and pH was 4.

Next, a performance evaluation test as an aqueous primer was performed on the aqueous primer liquid obtained as described above. The results are shown in Table 2 in comparison with Conventional Examples 1 and 2.

Conventional example 1: Acrylic emulsion primer (Acryset EMN-17E, manufactured by Nippon Shokubai Co., Ltd.) Conventional example 2: Alkali cross-linked polyacrylic ester emulsion (Primal E-1126, manufactured by Rohm & Haas) From the results shown in Table 2, sample Nos. 1, 2, and 8 are represented by the above general formula (I).
Since it does not contain 0.3 mol% or more of the structural unit represented by, it is clear that the performance is remarkably inferior to that of the other sample Nos. That is, the structural unit represented by the general formula (I) is at least 0.3 mol%, and the chain polymer (A
It is necessary to be included in the component), and it is understood that the desired effect cannot be obtained unless such a substance is used.

Further, in the case of the conventional emulsion type primer, not only the non-alkali cross-linking type (conventional example 1) but also the alkali cross-linking type (conventional example 2) do not sufficiently penetrate into the base material, The effect is not always satisfactory.

[Example 2] An aqueous composition containing various chain polymers (component A) was prepared according to Example 1 except that the type of the cationic alkali cross-linking monomer was changed, and the primer performance thereof was evaluated. did. The monomer composition of each polymer and the test results in this case are shown in Table 3.

All of the polymerization products were homogeneous aqueous solutions, and the results of using them as primers were good.

[Example 3] Using the four-necked flask of Example 1 further equipped with a dropping funnel, two-step polymerization was carried out with the composition shown in Table 4, and the chain polymer of the component (A) and the chain polymer (B) were used. An aqueous solution for a primer containing both of the insoluble polymers of the components was prepared.

The first-stage reaction was carried out according to Example 1 by stirring at 65 to 70 ° C. for 3 hours. After a lapse of 3 hours, a part of the reaction solution was sampled and the reaction rate was measured, and all showed a reaction rate of almost 100%. Next, add the concentration-adjusted water over 10 to 30 minutes, taking care not to lower the internal temperature, then add the reaction initiator V50 for the second stage reaction all at once and continue to 65 to 7
While maintaining the temperature at 0 ° C, the monomer emulsion prepared from each component other than V50 was used for about 2 hours (however, for sample Nos. 22 and 23, 30
After the completion of the dropwise addition, the reaction was continued at the same temperature for 7 hours. The reaction rate at this time was almost 100%.

5% of the aqueous primer solution obtained as described above
The isopropanol aqueous solution of was used to adjust the concentration so that the total content (polymer concentration) of the component (A) and the component (B) was about 20%, and using this, the primer performance was adjusted in the same manner as in Example 1. evaluated. The results are shown in Table 5.

As is clear from Table 5, in Sample Nos. 17 and 18, the proportion of the component (A) in the total polymer was less than 10%, and therefore, the primer performance was remarkably reduced. I understand. Samples Nos. 19 to 23 have a ratio of the component (A) of more than 10%, and all show good primer performance.

In the adhesion test, the coating amount of the No. 18 sample on the base material was set to 260 g / m ^{2, which} is double the usual amount, and the coating amount of the soluble polymer per unit area (apparent coating amount) was set to No. Almost no improvement in adhesion was observed even when the amount was about the same as that of the sample of .19.

[Example 4] The aqueous composition of Sample No. 11 was used as the chain polymer of the component (A). In addition, the sample as an insoluble polymer of the component (B)
No. 17 emulsion or emulsion obtained by polymerizing with the following composition according to sample No. 17 (Emulsion X) was mixed with the composition shown in Table 6 below to obtain an aqueous primer solution. .

〔composition〕

Butyl acrylate 50 parts Methyl methacrylate 48 〃 Dimethyldiallylammonium chloride 2 〃 Emulgen 935 4 〃 Water 156 〃 Ammon persulfate 0.3 〃 [General properties] Nonvolatile content 38.2% Viscosity 200 cps pH 2.8 Minimum film forming temperature 5 ℃ The primer performance was evaluated in the same manner as in Example 1 for the thus obtained aqueous liquid for a primer. The results are shown in Table 6.

As is clear from the results shown in Table 6, an aqueous composition having good primer performance was prepared by blending the chain polymer solution of the component (A) and the insoluble polymer emulsion of the component (B). It is possible to

In addition, the results of Table 6 and the fifth example of Example 3
From the results shown in the table, it can be seen that even in the case of the insoluble polymer as the component (B), one containing a cationic alkali crosslinkable monomer [general formula (I ')] as a constitutional unit gives more preferable results. .

Was evaluated in the same manner as in Example 1.

[Example 5] A pigment and an antifoaming agent were further mixed in the aqueous liquids for primers of Sample Nos. 11 and 12 in the following proportions to prepare a paint, and the primer performance of this paint was evaluated in the same manner as in Example 1.

[Paint formulation]

Water-soluble resin (Sample No. 11) 100 parts No. 1 clay (made by Maruo Calcium Co., Ltd. ) 5〃 Defoamer (Nopco 8034) 0.05〃 105.05〃 The adhesion test of the above paint to asbestos cement calcium silicate board was conducted in Example 1 No. 11 of No. 11 was good.

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Claims (5)

[Claims] 1. The following components (A) and (B) in an aqueous medium are (A) / (B) = 90 / 10-100 by weight.
An aqueous liquid for a primer, which is contained at a ratio of / 0. (A) A chain polymer which is soluble in the above aqueous medium and contains at least 0.3 mol% of a structural unit represented by the following formula (I) in the molecular structure. (B) A polymer insoluble in the aqueous medium. 2. The aqueous solution for a primer according to claim 1, wherein the aqueous medium is a mixed solution of water and an organic solvent which is easily soluble in water, or water. 3. The aqueous solution for a primer according to claim 1, wherein the chain polymer as the component (A) is an acrylic resin. 4. The aqueous primer solution according to claim 1, wherein the polymer of component (B) is a polymer of an olefinic unsaturated monomer used in emulsion polymerization. 5. The first content according to claim 1, wherein the total content of the component (A) and the component (B) is set to 5 to 30% by weight.
An aqueous solution for a primer according to the item.