JPH08104702A - Production of water-based adhesive filled with inorganic filler - Google Patents

Abstract

PURPOSE: To produce a water-based adhesive filled with an inorganic filler and excellent in adhesion in the ordinary state, water-resistant adhesion and dispersion stability. CONSTITUTION: An inorganic orgaosol is dispersed in a vinyl monomer, and the dispersion is emulsion-polymerized.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an aqueous adhesive containing an inorganic filler.

[0002]

2. Description of the Related Art Recently, there is a demand for an adhesive that does not use an organic solvent having a low flash point due to environmental problems, etc., and it is safe and easy to handle (easy to dilute with water, easy to wash equipment used). , The viscosity change can be reduced by increasing the molecular weight and concentration of the adhesive-based polymer), and economically, the conversion to water-based adhesives is being actively carried out. However, in general, water-based adhesives are inferior in adhesive performance such as water resistance and weather resistance as compared with conventionally used organic solvent-based adhesives, and various attempts have been made to improve these performances. There is.

As one of the above-mentioned attempts, an emulsion adhesive is blended with an inorganic material. Since the emulsion of the adhesive is in a thermodynamically metastable state, it is aggregated by blending the inorganic material. In some cases, the inorganic material itself did not disperse uniformly and settled, making the quality of the adhesive unstable.

Therefore, a synthetic resin containing a filler, characterized in that a filler is added to the emulsion polymerization system before the initiation of the emulsion polymerization of the olefin-based or diene-based monomer or during the emulsion polymerization reaction to cause polymerization. A method for producing an emulsion is proposed in Japanese Patent Application Laid-Open No. 50-32279, and compared with a synthetic resin emulsion in which a filler is simply added,
It is described that the synthetic resin emulsion containing the filler obtained by the same method has high stability, and the film obtained from the emulsion has excellent water resistance.

However, the adhesive composed of the synthetic resin emulsion containing the filler obtained by the above-mentioned method has a low affinity for the inorganic filler and the emulsion polymer of the olefinic or diene monomer, so that the olefinic adhesive is used. Or, the dispersion state of the inorganic filler in the emulsion polymer particles of the diene-based monomer is not sufficient, and the stability of the emulsion is higher than that obtained by simply mixing the synthetic resin emulsion and the inorganic filler. Although it has improved somewhat, it is still not sufficient. In addition, the adhesive strength is slightly improved by slightly observing the filling effect on the rough surface, but the strength of the dry film is insufficient due to the poor dispersion of the filler in the above polymer. Not enough.

[0006]

The object of the present invention is to solve the above-mentioned problems and to produce an aqueous adhesive containing an inorganic filler excellent in normal-state adhesiveness, water-resistant adhesiveness and dispersion stability. To provide a method.

[0007]

[Means for Solving the Problems]

The present invention relates to a method for producing an aqueous adhesive containing an inorganic filler, which comprises dispersing an inorganic organosol (B) in a vinyl monomer (A) and then emulsion-polymerizing it. This is the summary.

Vinyl monomer (A) used in the present invention
As, vinyl acetate, vinyl propionate, Veov
vinyl esters such as a (tertiary vinyl carboxylate),
Methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, (meth) acrylic (Meth) acrylic acid esters such as acid dodecyl, styrene,
Examples thereof include alkenylbenzenes such as α-methylstyrene, vinyltoluene and t-butylstyrene, unsaturated halides such as vinyl chloride, vinylidene chloride and vinyl bromide, and unsaturated nitriles such as acrylonitrile. The vinyl monomer (A) may be used alone or in combination of two or more kinds.

Further, the vinyl-based monomer (A) is a monomer copolymerizable with (meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid or the like α, β-.
You may use together with unsaturated carboxylic acid.

The inorganic organosol (B) used in the present invention is a colloidal solution in which inorganic filler particles are stably dispersed in an organic solvent, and generally used inorganic colloidal particles are stably dissolved in water. The dispersion medium of the dispersed inorganic hydrosol is obtained by replacing water with an organic solvent.
Depending on the degree of hydrophilicity of the organic solvent used, the inorganic filler particles are appropriately subjected to a surface treatment with a hydrophobic synthetic resin to be hydrophobized for use.

As the dispersion medium of the above-mentioned inorganic organosol (B), an organic solvent which can be mixed with the above-mentioned vinyl-based monomer (A) in an arbitrary ratio is used. Especially, a solvent having a low compatibility with water is polymerized. The dispersibility of the inorganic filler in the polymer particles when performing is excellent.

The average particle size of the inorganic filler particles is 2
It is 0 μm or less, preferably 5 μm or less. If the average particle size of the inorganic filler particles exceeds 20 μm, the performance of the colloid particles is lost, and the particles are separated from the inorganic organosol and easily settle.

Since the above-mentioned inorganic organosol (B) has the above-mentioned constitution, it can be produced arbitrarily, but the trade name is "IPAS".
T "(dispersion medium: isopropanol), trade name" DMAC
-ST "(dispersion medium: dimethylacetamide), trade name" XBA-ST "(dispersion medium: xylene, n-butanol mixed solvent), trade name" MIBK-ST "(dispersion medium: methyl isobutyl ketone), antimony pentoxide For sol, trade name "Sun colloid ATL-130" (dispersion medium: toluene), trade name "Sun colloid AME-130" (dispersion medium: methyl ethyl ketone) product name "Sun colloid AME-"
Examples of commercially available products include 130 "(dispersion medium: methyl ethyl ketone) [above, manufactured by Nissan Chemical Industries, Ltd.].

In the present invention, an inorganic organosol (B) is dispersed in the vinyl-based monomer (A), and then emulsion-polymerized to contain an inorganic filler, that is, an aqueous adhesive containing the inorganic filler. An aqueous dispersion of a vinyl-based polymer containing the above is obtained. As a method for adding the mixture of the vinyl-based monomer (A) and the inorganic organosol (B) to the polymerization system, both are sufficiently mixed before the initiation of the polymerization. Any method may be used, such as a method of adding, a method of adding all at once before the start of polymerization, a method of continuously adding during polymerization, a method of adding in multiple stages during polymerization.

As a method for dispersing and emulsifying the inorganic organosol (B) in the vinyl monomer (A), an aqueous solution of the vinyl monomer (A), the inorganic organosol (B) and a surfactant is used. For example, a method of mixing with a high shear mixing device such as a dissolver, a homomixer, or a homogenizer is used.

As the above-mentioned surfactant, anionic, nonionic or cationic surfactants used in ordinary emulsion polymerization can be used. Examples of the anionic surfactant include fatty acid salts such as potassium oleate, metal alkylsulfates such as sodium lauryl sulfate, and alkylallylsulfonates such as sodium dodecylbenzenesulfonate.

Examples of the nonionic surfactant include polyoxyethylene alkyl allyl ethers such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether, polyoxy ethylene lauryl ether and polyoxyethylene stearyl ether. Examples thereof include ethylene alkyl ethers, polyoxyethylene higher fatty acid esters, ethylene oxide-propylene oxide / block copolymers and the like.

Examples of the cationic surfactant include alkylammonium salts such as lauryltrimethylammonium chloride and stearyltrimethylammonium chloride, and alkylbenzylammonium salts such as stearyldimethylbenzylammonium chloride.

Further, a water-soluble oligomer composed of polycarboxylic acid, polysulfonate or the like may be used in place of or in combination with the above surfactants. Further, a water-soluble polymer substance such as polyvinyl alcohol or hydroxyethyl cellulose may be used as a protective colloid.

The polymerization initiator used in the above-mentioned polymerization reaction is dissolved in water or dissolved in heated water to generate a radical by heating (or in the presence of an auxiliary agent), and the vinyl-based monomer ( It is not particularly limited as long as it can polymerize A) and the like, and examples thereof include inorganic peroxides such as hydrogen peroxide, inorganic persulfates such as ammonium persulfate and potassium persulfate, benzoyl peroxide, cumene hydro. Examples thereof include organic peroxides such as peroxides and percarboxylic acids such as peracetic acid. These polymerization initiators may be used alone or in combination of two or more kinds.
Further, these polymerization initiators are sodium hydrogen sulfate, L
-It may be used as a redox polymerization initiator in combination with a reducing agent such as ascorbic acid.

In addition to the above, a chain transfer agent such as mercaptans and diaryldisulfides, pH is added to the above polymerization system.
A preparation agent, an organic solvent, etc. may be appropriately used as necessary within the scope not departing from the spirit of the present invention.

If desired, the emulsion polymer containing the inorganic filler obtained by the above polymerization reaction may contain a plasticizer, a solvent, a dispersant, a thickener, a defoaming agent, a pH adjusting agent, and a rust preventive agent. , Of course, preservatives, ultraviolet absorbers, antioxidants, heat stabilizers, colorants, and the like, of course, may be used by appropriately adding additives conventionally used for adding respective functions to the emulsion polymer. Is.

[0024]

The inorganic organosol (B) is dispersed in the vinyl monomer (A) of the present invention and then emulsion-polymerized, so that the inorganic organosol (B) is vinyl-based during the polymerization reaction process. Is it because of being taken into the polymer,
An extremely stable emulsion is formed, and the coating film obtained by coating and drying the polymer has inorganic filler particles uniformly dispersed in the vinyl polymer, and the coating strength is tough. , Showing a strong adhesive strength.

[0025]

EXAMPLES The present invention will now be described in more detail by way of examples.

(Example 1) 92 parts by weight of styrene, 55.5 parts by weight of butyl acrylate, 28.
5 parts by weight, 24 parts by weight of acrylic acid, and an organosilica sol having a dispersion medium of isopropanol (manufactured by Nissan Chemical Industries,
Product name: IPA-ST, solid content = SiO ₂ 30% by weight,
133 parts by weight of average particle diameter 10 to 15 nm) and 184 parts by weight of an aqueous solution prepared by dissolving 4 parts by weight of sodium lauryl sulfate in 180 parts by weight of deionized water are mixed with TK Homo Disper (manufactured by Tokushu Kika Kogyo Co., Ltd.), and mixed and emulsified. I got a thing. Then
A 1-liter separable flask equipped with a stirrer, a reflux condenser, a nitrogen introducing tube and a dropping funnel was charged with 167 parts by weight of deionized water, and then the temperature was raised to 70 ° C. while substituting with nitrogen.
Then, 2 parts by weight of a 5% by weight aqueous solution of ammonium persulfate was added, and the above mixed emulsion was added dropwise from a dropping funnel to initiate polymerization. After 3 hours, the addition was completed and the temperature was increased to 2 at 70 ° C.
Heated for hours to complete the reaction. The solid content of the obtained vinyl polymer emulsion containing the silica filler is 35.
% By weight.

Example 2 An organosilica sol having a dispersion medium of methylisobutylketone in place of the organosilica sol having isopropanol used as a dispersion medium (manufactured by Nissan Chemical Industries, Ltd., trade name: MIBK-ST, solid) Min = SiO ₂ 30% by weight, average particle size 10 to 15 nm) was used to obtain a vinyl polymer emulsion containing a silica filler having a solid content of 35% by weight in the same manner as in Example 1. .

Example 3 An organosilica sol (manufactured by Nissan Chemical Industries, Ltd., trade name: XBA) having a xylene-n-butanol mixed solvent as a dispersion medium was used in place of the organosilica sol having isopropanol as a dispersion medium used in Example 1. -S
T, solid content = SiO ₂ 30% by weight, average particle size 10 to 1
A vinyl polymer emulsion containing a silica filler having a solid content of 35% by weight was obtained in the same manner as in Example 1 except that (5 nm) was used.

Example 4 An organosilica sol having a dispersion medium of toluene instead of the organosilica sol having a dispersion medium of isopropanol used in Example 1 (manufactured by Nissan Chemical Industries, Ltd., trade name: Sun Colloid ATL-130, solid) Min =
A vinyl polymer emulsion containing a silica filler having a solid content of 35 wt% was obtained by the same method as in Example 1 except that Sb ₂ O _{5 was} 30 wt% and the average particle size was 10 to 15 nm). .

Comparative Example 1 A vinyl polymer emulsion having a solid content of 35% by weight was obtained in the same manner as in Example 1 except that an organosilica sol having isopropanol as a dispersion medium was not used.

(Comparative Example 2) To 200 parts by weight of the vinyl polymer emulsion obtained in Comparative Example 1, 48 parts by weight of the organosilica sol having the isopropanol used in Example 1 as a dispersion medium was added, and the mixture was sufficiently stirred and mixed. Thus, a vinyl polymer emulsion containing a silica filler having a solid content of 35% by weight was obtained.

(Comparative Example 3) To 200 parts by weight of the vinyl polymer emulsion obtained in Comparative Example 1, 48 parts by weight of antimony pentoxide sol having toluene as a dispersion medium used in Example 4 was added, and the mixture was thoroughly mixed. The mixture was stirred and mixed to obtain a vinyl polymer emulsion containing an antimony pentoxide sol having a solid content of 35% by weight.

(Comparative Example 4) 40 parts by weight of hydrophilic silica particles (manufactured by Nippon Aerosil Co., Ltd., trade name: Aerosil 130, average particle size 16 nm) were used in place of the organosilica sol having isopropanol as a dispersion medium used in Example 1. The amount of deionized water charged to the polymerization system is from 167 parts by weight to 26 parts by weight.
A vinyl polymer emulsion containing a silica filler having a solid content of 35% by weight was obtained in the same manner as in Example 1 except that the amount was increased to 0 part by weight.

The following tests were carried out on the dispersion stability, normal-state adhesive strength and water resistance of the emulsions obtained in each of the above Examples and Comparative Examples. The test results are shown in Table 1.

1. Dispersion stability: Emulsion 1 obtained
Take 0 g and centrifuge at 5000 rpm for 10 minutes,
The dry weight of the sediment was measured to determine the weight percent of sediment in the emulsion.

2. Normal-state adhesive strength: The obtained emulsion is applied to a bag material so that the coating amount in terms of solid content is 60 g / m ² , and two sheets are stuck together, and the temperature is 23 ° C. and the tightening pressure is 10 k.
Bonding was performed in this state for 1 hour at g / cm ² . Furthermore,
After curing for 3 days at a temperature of 23 ° C and a relative humidity of 60%,
According to JIS K-6852, the normal adhesive strength is set to 23
Measured as compressive shear adhesion at ° C.

3. Water resistance: A test piece prepared by the same method as the above-mentioned normal adhesive strength was immersed in water at 30 ° C. for 3 hours, then immersed in water at 20 ° C. for 10 minutes, and in a wet state, JIS K-6852 was used. Similarly, the water resistant adhesive strength was measured as the compression shear adhesive strength at a temperature of 23 ° C.

[0038]

[Table 1]

[0039]

EFFECTS OF THE INVENTION Since the present invention is constituted as described above, the inorganic filler contained therein is uniformly dispersed in the vinyl polymer molecule to form a stable emulsion without settling, It is a method for producing a water-based adhesive containing an inorganic filler that can provide an extremely excellent coating workability and can stably provide an adhesive having excellent normal-state adhesive strength and water-resistant adhesive strength.

Claims (1)

[Claims] 1. A method for producing an aqueous adhesive containing an inorganic filler, which comprises dispersing an inorganic organosol (B) in a vinyl-based monomer (A) and then emulsion-polymerizing it.