JPH01289804A - Water-dispersed resin composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. having excellent film adhesiveness, resistance to front damage etc. by emulsion-polymerizing an alpha,beta-ethylenically unsatd. monomer contg. a specified amt. of a polyfunctional monomer in an aq. medium contg. a specified amt. of a colloidal silica, an aq. urethane resin and a surface active agent. CONSTITUTION:At least one alpha,beta-ethylenically unsatd. monomer (e.g., methyl methacrylate or methacrylic acid) contg. 0.2-8wt.% polyfunctional monomer having 2 or more polymerizable functional groups (e.g., ethylene glycol dimethacrylate) is emulsion-polymerized in the presence of 3-25wt.% colloidal silica in terms of solid content based on the whole monomers and 3-30wt.% aq. urethane resin in an aq. medium contg. a surface active agent (e.g., sodium alkylbenzenesulfonate). It is thereby possible to prepare a water-dispersed resin compsn. suitable for paints etc.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a novel water-dispersed resin composition, more specifically, it has good film-forming properties, excellent adhesion, durability, and frost damage resistance. It is used for water-dispersed resin compositions that form a film.

(Prior Art) Conventionally, organic-inorganic composite coating films that have both the adhesion and flexibility features of organic polymers and the hardness and durability features of inorganic polymers have been developed.9 For example, vinyl acetate resin, There was a coating material whose main ingredients were a blend of acrylic resin emulsion, colloidal silica, and hydraulic binders (cement, gypsum).

In this case, the inorganic polymer is physically dispersed in the organic polymer, or conversely, the organic polymer is physically dispersed in the inorganic polymer, and not only is it difficult to balance the two, but their mutual bond is weak, resulting in poor long-term durability. I felt anxious.

Furthermore, in JP-A-59-71316, an aqueous resin dispersion obtained by using a silane monomer and colloidal silica as copolymerization components was disclosed, which attempted to chemically bond an inorganic polymer and an organic polymer.

This patent claims that cross-linking is formed between the silane monomer and colloidal silica during the emulsion polymerization process, resulting in good compatibility between the inorganic and organic polymers, resulting in water and alkali resistance and stain resistance. It is characterized by its superior properties. However, the stability of the obtained paint is poor and it cannot withstand long-term storage, and the paint film is non-uniform and when silane monomers or colloidal silica are used, the paint film shrinks and the cohesive force is strong, causing the paint film to deteriorate. Cracks may occur, and durability remains a problem.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems of the prior art, and mutually exhibits the features of organic-screen polymers, resulting in excellent film forming properties, adhesion properties, and durability. The object of the present invention is to provide an organic-inorganic composite water-dispersed resin composition that forms a film with excellent properties and frost damage resistance.

(Means to be Solved by the Invention) The present inventors used an aqueous urethane resin in the presence of colloidal silica, and simultaneously carried out emulsion polymerization in the presence of colloidal silica, or after the emulsion polymerization, by using a polyfunctional monomer. The present invention was achieved by confirming that crosslinking solved the problem.

That is, the present invention uses a polyfunctional monomer (monomer (a)) having two or more polymerizable functional groups at a concentration of 0. 2 to 8 weight]%, including
At least one α,β-ethylenically unsaturated monomer (monomer (b)) (however, the sum of (a) + (b)) is 100% by weight) based on the total monomers. It relates to a water-dispersed resin composition obtained by emulsion copolymerization in an aqueous medium containing a surfactant in the presence of colloidal silica with a solid content of 3 to 25% by weight and an aqueous urethane resin of 3 to 30% by weight. be.

Examples of the polyfunctional monomer (monomer (a,)) having two or more polymerizable functional groups used in the present invention include divinyl compounds, di(meth)acrylate compounds, and diallyl compounds. , for example, divinylhenzene, ethylene glycol di(meth)acrylate, diethylene glycol (meth)acrylate, triethylene glycol (meth)acrylate, trimethylolpropane tri(meth)
Examples include acrylate, diallyl phthalate, etc., and one or more of these may be used.

Monomer (a) forms monomer (b) due to the intraparticle crosslinking effect.
It is used to microscopically control the phase separation of the copolymer and water-based urethane resin to improve both adhesion and durability. Monomer (a) is used in an amount of 0.2 to 8% by weight of the total monomers, and if 0.2% by weight is ungrooved, the storage stability will be poor and the desired durability will be reduced; If it is used in an amount exceeding 8% by weight, the polymerization stability will be extremely poor, the viscosity will increase, and eventually gelation will occur, which are both undesirable.

α,β-ethylenically unsaturated monomer used in the present invention (
The monomer b)) is a monomer having one or more radically polymerizable ethylenically unsaturated monomers in the molecule, such as methyl (meth)acrylate, ethyl (meth)acrylate, etc.
(Meth)acrylic acid esters such as acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, and lauryl (meth)acrylate: styrene, vinyltoluene, α−
Aromatic unsaturated monomers such as methylstyrene: hydroxyethyl (meth)acrylate, hydroxypropyl (
Hydroxyl group-containing unsaturated monomers such as meth)acrylate: Carboxyl group-containing unsaturated monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid: Glycidyl (meth)acrylate, Glycidyl group-containing unsaturated monomers such as allyl glycidyl ether: (meth)acrylonitrile, (
Examples include nitrogen-containing unsaturated monomers such as meth)acrylamide and N-methylol(meth)acrylamide, and one or more of these may be used in any silk combination. Monomer (b) is a main component in designing the resin of the present invention, along with monomer (b), and is appropriately selected so as to obtain desired film performance and film forming properties.

The colloidal silica used in the present invention is an ultrafine silica sol in which negatively charged amorphous silica particles are colloidally dispersed in water, and has a spherical particle size of 1 to 100 mμ. For example, Applied (Asahi Denka Kogyo M), Cataloid (
There are various grades such as Catalysts Kasei Kogyo Co., Ltd.) and Snowtex (Yasan Kagaku Kogyo Co., Ltd.), and any of them can be used, but if the PH of colloidal silica is less than 3,
When aqueous urethane resin is adsorbed, aggregates tend to form, and if the pH exceeds 10, the polymerization reaction is difficult to proceed.
Since the system becomes unstable, it is preferable to select one having a pH of 3 to 10. Colloidal silica is used in a solid content of 3 to 25% by weight based on the total monomers. If the amount used is less than 3% by weight, affinity with the inorganic substrate will not be obtained, the permeability and adhesion to the substrate will be poor, and the hardness and durability of the organic-inorganic composite coating will be affected. will decrease.

On the other hand, if it is used in an amount exceeding 25% by weight, the cohesive force of the film becomes strong and brittle, and the appearance of the film tends to be impaired, which is not preferable.

The aqueous urethane resin used in the present invention can be produced by various methods, such as 1) reacting a polyether polyol or polyester polyol with an organic polyisocyanate to synthesize a prepolymer having terminal NCO groups; A reaction product is obtained by reacting this with an ionic or ion-forming compound, or by mixing these components from the beginning and reacting them. This reaction product is emulsified and dispersed in water to obtain an aqueous urethane resin. Further, an ion-forming compound is dissolved in water in advance, and a polyurethane prepolymer having terminal NGO groups is added thereto to obtain an aqueous urethane.

(2) A hydrophilic polymer compound containing a reactive hydrogen atom is used in combination with a hydrophilic polyol, reacted with an organic polyisocyanate, and then mixed with water to obtain an aqueous urethane resin. (3) A polyether polyol or a polyester polyol is reacted with an organic polyisocyanate to synthesize a prepolymer having terminal NGO groups, and a chain extender is added to this in the presence or absence of a solvent to extend the chain (crosslinking). ) and then add an aqueous surfactant solution to emulsify it to obtain an aqueous urethane resin. Alternatively, a prepolymer having a terminal NGO group is pre-emulsified with an aqueous surfactant solution and then a chain extender is added thereto. (4) Synthesize a prepolymer having a terminal NGO group by reacting a polyol with an organic isocyanate, add a surfactant to the prepolymer as it is, or block the terminal isocyanate group with a blocking agent, and disperse and emulsify it in water. Alternatively, there are methods such as adding it to an aqueous solution containing a surfactant to obtain an aqueous urethane resin, but as an aqueous urethane resin, NeoRez (Pol
Commercial products such as yvinyl Chemicals), Pibond (Bayer), Superflex (Daiichi Kogyo Kagaku), Orestar (Mitsui Toatsu Chemical), and Vermarine (Sanyo Chemical) are readily available. It is available and can be used conveniently. In order to obtain a water-dispersed resin having excellent film properties, it is preferable to select a resin having a tensile strength characteristic of 200 Kg/cm2 or more at break.

Water-based urethane resin adsorbs during emulsion polymerization in the presence of colloidal silica, improves the compatibility of organic and inorganic polymers, and also alleviates the cohesive force of colloidal silica, imparting film-forming properties and penetrating the material. Also, organic-
It is necessary to maximize the characteristics of inorganic materials and further improve durability. Solids content 3-30 based on total monomers
It is used in an amount of 1i%. If the amount used is less than 3% by weight, the storage stability will be poor and the organic-inorganic bond will be weak. On the other hand, if it is used in an amount exceeding 30% by weight, the polymerization reaction will be difficult to proceed and a large amount of aggregates will be generated.
Both are unfavorable since it is difficult to carry out stable emulsion polymerization and durability such as alkali resistance and weather resistance tends to deteriorate.

In the present invention, monomer (b) containing monomer (a) in the above-mentioned specific ratio is emulsion polymerized in an aqueous medium containing a surfactant in the presence of colloidal silica and an aqueous urethane resin, and an organic - An inorganic composite water-dispersed resin is obtained, which is manufactured by the following method.

Emulsion polymerization of monomer (b) is carried out by a conventionally known method, in which colloidal silica and aqueous urethane resin are present in the polymerization system during emulsion polymerization.
) Colloidal silica and water-based urethane resin, surfactant,
A method of emulsion polymerizing monomer (b) by introducing an initiator and other additives into the reaction system; (2) colloidal silica and aqueous urethane resin separately in a reaction system containing a surfactant; 3) A method of emulsion polymerization of monomer (b) while adding it to a reaction system containing a surfactant. There is a method of emulsion polymerization of
Although none of these affects the essence of the present invention, a particularly preferred method is to add a mixed solution of colloidal silica and aqueous urethane resin and monomer (b) to an aqueous medium containing a surfactant and an initiator. It is preferable to carry out emulsion polymerization by continuous or divided dropwise introduction, respectively.

The surfactants used in the emulsion polymerization of the present invention include higher alcohol sulfate, sodium alkylbenzene sulfonate, disodium monoester sulfosuccinate, sodium dialkyl sulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, polyoxyethylene alkylphenyl Anionic emulsifiers such as sodium ether sulfate: Nonionic emulsifiers such as polyoxyethylene alkylphenol ether, ethylene oxide and propylene oxide block copolymers:
Polymerizable emulsifiers such as alkali salts of alkylaryl sulfosuccinates: Oligomeric emulsifiers such as salts of low polymerization degree polycarboxylic acids: Water-soluble polymers such as polyvinyl alcohol, hydroxyethyl cellulose, and ethylene-maleic anhydride copolymers are used. be done.

As the radical 1 initiator, for example, water-soluble initiators such as ammonium persulfate, potassium persulfate, sodium persulfate, and hydrogen peroxide can be used alone or in combination. Further, a redox initiator may be prepared by using these initiators and a reducing agent such as sodium bisulfite or L-7 scorvin. In addition, chain transfer agents, PH buffers, and organic solvents can be optionally used in the polymerization system. For example, aqueous ammonia, triethylamine, morpholine, sodium hydroxide,
The polymer may be neutralized with a basic compound such as lithium.

The water-dispersed resin obtained by the present invention can be added with pigments (titanium dioxide, calcium carbonate, red iron, carbon), film-forming aids, dispersants, thickeners, antifoaming agents, preservatives, etc. as necessary. is also possible.

The water-dispersed resin obtained by the present invention exhibits a synergistic effect of organic polymer and inorganic polymer, and has excellent film-forming properties.
Significantly improved and durable film performance was observed;
Although the theory based on the composition is not necessarily clear, it is believed that during the emulsion polymerization process, an aqueous polyurethane dispersion with strong crosslinks interfaces with colloidal silica, causing mutual entanglement of the polymers and the formation of some grafting. It is considered that a hybrid water-dispersible resin can be obtained having a particle structure similar to the above. Furthermore, during the film formation process, a siloxane bond is formed through a condensation and dehydration reaction of silanol groups on the surface of the colloidal silica with microscopic phase separation controlled by the aqueous urethane resin having a crosslinked structure and the intraparticle crosslinked organic polymer. It is thought that a film is formed and a film with a 1# island structure with excellent compatibility is formed, forming an organic-inorganic composite film that is stronger than a simple mixture.

(Effects) The water-dispersed resin composition of the present invention is suitable for use in paints. Films can be formed on solid cement base materials, asphalt and other clear sound quality base materials, ceramics, glass, paper, wood, plastics, metals, etc. by heating at room temperature or relatively low temperatures. Furthermore, it is possible to form a coating film with excellent adhesion, unprecedented durability, and excellent frost damage resistance, which is essential in cold regions.

(Examples and Comparative Examples) Examples and Comparative Examples will be given to specifically explain the present invention. All percentages written on the opposite side represent % by weight, and parts represent parts by weight.

Example 1 A 1Q separable flask was equipped with a thermometer, a stirring bar, a cooling tube, a nitrogen gas introduction tube, and two dropping funnels, and 200 parts of deionized water, 8 parts of disodium monoester sulfosuccinate, and sodium hydrogen carbonate were added. 1.5 parts were charged, and the temperature was raised to 75°C in a water bath while purging with nitrogen.

Monomer mixture of 93 parts methyl methacrylate, 52 parts n-butyl acrylate, 5 parts methacrylic acid, 8 parts 2-hydroxyethyl methacrylate, 5 parts ethylene glycol dimethacrylate, 10 parts deionized water, NeoRez
40 parts of R-960 (33% solids), Applied A
A mixed solution of 50 parts of T-30A (solid content 30%), 1 part of monoester disodium sulfosuccinate, and 10 parts of ammonium persulfate aqueous solution (concentration 15%) was added dropwise to 80% at the same time in separate dropping funnels over 4 hours. The reaction was carried out at °C. After completion of the dropwise addition, the mixture was further aged for 2 hours while maintaining the salinity, and then cooled to room temperature to obtain a stable emulsion with a non-volatile content of 42%.

Example 2 A 1Q separable flask was equipped with a thermometer, a stirring bar, a cooling tube,
Equipped with a nitrogen gas introduction pipe and three dropping funnels, 200 parts of deionized water, 8 parts of disodium monoester sulfosuccinate, and 1.5 parts of sodium hydrogen carbonate were charged, and the temperature was raised to 75°C in a water bath while purging with nitrogen. Made it warm. A monomer mixture of 40 parts of methyl methacrylate, 45 parts of styrene, 60 parts of n-butyl acrylate, 6 parts of methacrylic acid, 8 parts of 2-hydroxyethyl methacrylate, and 5 parts of ethylene glycol dimethacrylate and an aqueous ammonium persulfate solution (concentration 15%) 10 The reaction was carried out at 80° C. for 4 hours using separate dropping funnels. From the remaining dropping funnel, at the same time as dropping the monomer mixture, 30 parts of Snowtex C (solid content 20%) was dropped over 2 hours, followed by Superflex #200.
120 parts (solid content: 30%) was added dropwise over 2 hours, and after aging for another 2 hours while maintaining the salinity, the mixture was cooled to room temperature to obtain a stable emulsion with a non-volatile content of 40%.

Example 3 A 1Q separable flask was equipped with a thermometer, a stirring bar, a cooling tube,
Equipped with a nitrogen gas introduction pipe and two dropping funnels, 200 parts of deionized water, 8 parts of disodium monoester sulfosuccinate and 1.5 parts of sodium hydrogen carbonate were charged, and the temperature was raised to 75°C in a water bath while purging with nitrogen. Made it warm. 85 parts of methyl methacrylate, 6 parts of n-butyl acrylate
0 parts of methacrylic acid, 8 parts of 2-hydroxyethyl methacrylate and 10 parts of deionized water, Ne
oRez R-96030 part, Applied AT-30
A 50 parts, monoester disodium sulfosuccinate 0. 5 parts, ammonium persulfate aqueous solution <A degree 15%
) 10 parts of the mixed solution were simultaneously added dropwise in separate dropping funnels over 4 hours to carry out the reaction at 80°C. After dropping, add 12 parts of ethylene glycol dimethacrylate to 10
The reaction was continued by dropping the solution over a period of minutes. After aging for another 2 hours while maintaining the salinity, the mixture was cooled to room temperature to obtain a stable emulsion with a non-volatile content of 43%.

Examples 4 to 9 and Comparative Examples 1 to 7 Emulsions were obtained in the same manner as in Example 3, except that the compositions of monomers, colloidal silica, and aqueous urethane resin were changed as shown in Table 1.

(Left below) Storage stability, film formation, adhesion, water resistance, alkali resistance, boiling water resistance, frost damage resistance, accelerated durability, and extralayer exposure for each emulsion obtained in Examples and Comparative Examples The results of the test were as shown in Table 2.

[Coating film creation conditions] 6 parts of butyl carbitol acetate was added to 100 parts of each emulsion obtained in the examples and comparative examples, and after sample preparation, 150 g of fl.
/m2 with a spray gun and dried for 10 minutes in a hot air dryer at 80°C. For the adhesion test, specimens were prepared on slate boards, concrete blocks, asphalt, silica boards, and carbon fiber reinforced concrete boards under the same coating film formation conditions as above. In addition, outdoor exposure tests were conducted using a water-based polymer (roofing emulsion paint made by Mizuno Paint Co., Ltd.) on a slate board.
A specimen was prepared under the same coating film forming conditions as described above on a coated plate which was coated with IL2f at 50 g/m2 and dried for one day at room temperature.

[Test method and evaluation method] Storage stability: The emulsion was placed in a hot air dryer at 50°C for 1 hour.
After storage for 0 days, the condition was visually observed.

Paint film formation property: The presence or absence of abnormalities in the appearance of the paint film after drying was observed using a stereomicroscope.

11 Adhesion 2 A cellophane tape peeling test was carried out using a crosscut with a width of 2 mm.

Water resistance: The product was immersed in water for 20 days and the condition was visually observed.

Alkali resistance: It was immersed in a 3% NaOH aqueous solution for 7 days, and the condition was visually observed.

Boiling water resistance: The product was immersed in boiling water for 2 hours and the condition was visually observed.

Freeze resistance: Test plate immersed in tap water at -20°C for 16
After 50 cycles, one cycle was 8 hours at 20°C, and the condition was visually observed.

Accelerated durability: UV irradiation after 8 hours immersion in water I'lJ16
The condition after 5 cycles was visually observed.

Outdoor exposure test: The appearance (gloss, staining, cracking, etc.) of the coating film was observed after 18 months.

Evaluation Criteria ◎ There was no change in condition at all, and there was no abnormality in adhesion after the test.

○ No change in condition after the test and good adhesion.

△ Slightly poor condition change and adhesion after testing.

X: State change is significant, and adhesion after the test is also extremely poor.

(The following are blank spaces) As a result of each test, Comparative Example 5 had extremely poor polymerizability and no emulsion was obtained, and Comparative Examples 4 and 7 produced multiple coagulates. Moreover, in Comparative Example 3, a continuous coating film was not formed and the following test was impossible. Comparative Examples 1, 2, and 6 were found to have satisfactory performance, and the water-dispersed resin compositions of Examples 1 to 9 provided coating films with excellent adhesion, frost damage resistance, and durability. This was recognized.

Patent applicant: Mizutani Paint Co., Ltd.

Claims (1)

[Claims] 1. At least one α,β-ethylenically unsaturated monomer containing 0.2 to 8% by weight of a polyfunctional monomer having two or more polymerizable functional groups (monomer (a)) (monomer (b)) (
However, the total of (a) + (b) is 100% by weight) in the presence of 3 to 25% by weight of colloidal silica and 3 to 30% by weight of aqueous urethane resin in terms of solid content based on the total monomers. A water-dispersed resin composition containing a surfactant and obtained by emulsion polymerization in an aqueous medium.