JP4071181B2 - Synthetic resin emulsion powder - Google Patents

Description

  The present invention relates to a synthetic resin emulsion powder, and more specifically, a vinyl alcohol polymer as a dispersant, and one or more unsaturated monomers selected from ethylenically unsaturated monomers and diene monomers. Synthetic resin emulsion powder obtained by drying a composition in which a vinyl alcohol polymer (B) containing 1 to 12 mol% of ethylene units is blended in an emulsion (A) having a polymer having a body unit as a dispersoid About.

The synthetic resin emulsion powder is produced by spray-drying the synthetic resin emulsion, and is superior in terms of handling and transportation because it is a powder compared to the synthetic resin emulsion. Further, in use, it is easily redispersed in water by adding water and stirring, and therefore, it is used in a wide range of applications such as an admixture to cement or mortar, an adhesive, and a binder for paint. Among them, the admixture for mortar is widely used because it is a powder and can be premixed and can be used in various commercial forms. However, in the conventional synthetic resin emulsion, when it is spray-dried as it is, the dispersoid easily melts and does not re-disperse in water, so a large amount of polyvinyl alcohol is added afterwards, and further as an anti-blocking agent. At present, it is necessary to use a large amount of inorganic powder such as silicic anhydride. As the polyvinyl alcohol to be added later, conventional partly saponified PVA has been widely used since it is necessary to re-emulsify after use after powdering (Patent Document 1). However, as is apparent from Comparative Examples 7 to 8 described later, the redispersibility of the obtained powder is not necessarily excellent enough, and the water resistance of the emulsion obtained by redispersing the obtained emulsion powder is not satisfactory. Has a problem that it is inferior to that before pulverization.
JP-A-11-263849 (Claims 1, [0011], [0012])

  The object of the present invention is to solve the above-mentioned problems, and is a synthetic resin excellent in redispersibility, excellent in water resistance, film forming property when redispersed, and standing stability at low temperatures. It is to provide an emulsion powder.

  As a result of intensive investigations in view of the above circumstances, the present inventors have found that one or two or more kinds of solvents selected from ethylenically unsaturated monomers and diene monomers using a vinyl alcohol polymer as a dispersant. A composition in which a vinyl alcohol polymer (B) containing 1 to 12 mol% of an ethylene unit in the molecule is blended in an emulsion (A) having a polymer having a saturated monomer unit as a dispersoid is dried. The synthetic resin emulsion powder obtained has been found to solve the above problems, and the present invention has been completed.

According to the present invention, it is possible to obtain a synthetic resin emulsion powder having excellent redispersibility, excellent water resistance, and excellent film-forming properties when redispersed and stability at low temperatures.
By using the emulsion powder of the present invention, an admixture for a hydraulic substance having excellent dispersibility in a hydraulic substance such as cement mortar and excellent strength of the obtained hydraulic substance can be obtained. Moreover, by using the emulsion powder of the present invention, a joining material for a hydraulic substance that is excellent in adhesiveness and durability and also excellent in mechanical strength can be obtained.

Hereinafter, the synthetic resin emulsion powder of the present invention will be described in detail.
In the present invention, the dispersoid of the emulsion (A) is composed of a polymer having one or more unsaturated monomer units selected from ethylenically unsaturated monomers and diene monomers. Examples of the ethylenically unsaturated monomer include olefins such as ethylene, propylene, and isobutene, halogenated olefins such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride, vinyl formate, vinyl acetate, vinyl propionate, Vinyl esters such as vinyl versatate and vinyl pivalate, acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, acrylic acid Acrylic acid esters such as t-butyl, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n methacrylate -Butyl, meta Methacrylic acid esters such as i-butyl acrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate and octadecyl methacrylate, nitriles such as acrylonitrile and methacrylonitrile, allyl such as allyl acetate and allyl chloride Compound, Styrene monomers such as styrene, α-methylstyrene, p-methylstyrenesulfonic acid and sodium and potassium salts thereof, trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, 3-acrylamidopropyl Trimethylammonium chloride, 3-methacrylamidopropyltrimethylammonium chloride, quaternary ammonium salt of N- (3-allyloxy-2-hydroxypropyl) dimethylamine, N- (4-allyloxy- 3-hydroxybutyl) diethylamine quaternary ammonium salt, acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetone acrylamide, N-methylolacrylamide, methacrylamide, N-methylmethacrylamide Quaternary ammonium salts such as N-ethylmethacrylamide and N-methylolmethacrylamide, hydroxypropyltrimethylammonium methacrylate methacrylate, hydroxypropyltrimethylammonium chloride acrylate, N-vinylpyrrolidone and the like, and diene monomers Examples thereof include butadiene, isoprene, chloroprene and the like. These monomers are used alone or in combination of two or more.
Among the polymers composed of the above monomer units, vinyl ester polymers typified by vinyl acetate polymers, olefin-vinyl ester copolymers typified by ethylene-vinyl acetate copolymers, etc. This is one of the preferred embodiments of the invention.

  In the present invention, a vinyl alcohol polymer is used as the dispersant for the emulsion (A). The vinyl alcohol polymer is produced, for example, by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester. The saponification degree of the vinyl alcohol polymer is not particularly limited, but is preferably 70 to 99 mol%, more preferably 80 to 98 mol%, and still more preferably 83 to 95 mol%. When the degree of saponification is less than 70 mol%, there is a concern that water solubility, which is the original property of the vinyl alcohol polymer, is lowered. Further, when the degree of saponification exceeds 99 mol%, there is a concern that emulsion polymerization becomes unstable. The viscosity average polymerization degree (hereinafter abbreviated as polymerization degree) of the vinyl alcohol polymer is not particularly limited, but is preferably in the range of 100 to 8000, more preferably 300 to 3000, and even more preferably 300 to 2500. Moreover, as a vinyl alcohol polymer of the dispersing agent of emulsion (A), a vinyl alcohol polymer having a 1,2-glycol bond of 1.9 mol% or more is preferably used. As a method for producing a polymer having a 1,2-glycol bond of 1.9 mol% or more, for example, a method of copolymerizing vinylene carbonate with a vinyl ester monomer so as to have the above 1,2-glycol bond amount, Alternatively, when polymerizing a vinyl ester monomer, a method of polymerizing under pressure at a temperature higher than normal conditions, for example, 75 to 200 ° C., may be mentioned. In the latter method, the polymerization temperature is not particularly limited, but is usually 95 to 190 ° C, preferably 100 to 180 ° C.

  The vinyl alcohol polymer may be a copolymer of an ethylenically unsaturated monomer that can be copolymerized within a range that does not impair the effects of the present invention. Examples of such ethylenically unsaturated monomers include acrylic acid, methacrylic acid, fumaric acid, (anhydrous) maleic acid, itaconic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, trimethyl- (3-acrylamide). -3-dimethylpropyl) -ammonium chloride, acrylamido-2-methylpropanesulfonic acid and its sodium salt, ethyl vinyl ether, butyl vinyl ether, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene N-vinylamides such as sodium vinylsulfonate, sodium allylsulfonate, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, and the like. Also, vinyl ester monomers such as vinyl acetate and the above ethylenically unsaturated monomers are copolymerized in the presence of thiol compounds such as thiol acetic acid and mercaptopropionic acid, and the resulting copolymer is saponified. It is also possible to use a terminally modified product obtained by doing so.

  The synthetic resin emulsion (A) used in the present invention is one or more monomers selected from ethylenically unsaturated monomers and diene monomers in the presence of the above-mentioned vinyl alcohol polymer. The synthetic resin emulsion powder is obtained by drying, particularly spray drying, the synthetic resin emulsion. In the production of the synthetic resin emulsion, as an initiator for emulsion polymerization, a polymerization initiator usually used for emulsion polymerization, that is, a water-soluble initiator such as potassium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroperoxide, etc. In addition, oil-soluble initiators such as azobisisobutyronitrile and benzoyl peroxide are used in redox systems alone or in combination with various reducing agents. Although there are no particular limitations on the method of using these, a method of adding in an initial batch, a method of adding continuously to a polymerization system, or the like can be employed.

In the synthetic resin emulsion (A) used in the present invention, the amount of the vinyl alcohol polymer used is not particularly limited, but is usually 2 to 30 parts by weight, preferably 3 to 15 parts by weight, based on 100 parts by weight of the monomer. More preferably, it is 3-10 weight part. When the vinyl alcohol polymer is less than 2 parts by weight, the polymerization stability of the synthetic resin emulsion is lowered, and the mechanical stability and chemical stability which are the characteristics of the synthetic resin emulsion using the vinyl alcohol polymer as a dispersant are characteristic. There is a concern that a decrease in film strength and a decrease in film strength may occur. On the other hand, when the amount of the vinyl alcohol polymer exceeds 30 parts by weight, there are concerns such as a problem of removal of reaction heat due to an increase in the viscosity of the polymerization system and a decrease in water resistance of the film.
There is no particular limitation on the method of adding the vinyl alcohol polymer, a method of adding all at once in the initial stage, a method of adding a part of the vinyl alcohol polymer in the initial stage, and continuously adding to the polymerization system during the polymerization, etc. There is.
In addition, a conventionally known nonionic, anionic, cationic or amphoteric surfactant or a water-soluble polymer such as hydroxyethyl cellulose may be used in combination with the vinyl alcohol polymer.

  As a method for adding a monomer when producing the synthetic resin emulsion (A) used in the present invention, a method of adding to the polymerization system all at once, adding a part of the monomer at the initial stage, and polymerizing the rest Various methods are possible, such as a method of continuously adding the monomer, water and a dispersant previously emulsified, and a method of continuously adding to the polymerization system.

Moreover, a chain transfer agent can also be added when manufacturing the synthetic resin emulsion (A) used for this invention. The chain transfer agent is not particularly limited as long as chain transfer occurs, but a compound having a mercapto group is preferable from the viewpoint of chain transfer efficiency. Examples of the compound having a mercapto group include alkyl mercaptans such as n-octyl mercaptan, n-dodecyl mercaptan and t-dodecyl mercaptan, 2-mercaptoethanol, and 3-mercaptopropionic acid.
The addition amount of the chain transfer agent is preferably 5 parts by weight or less with respect to 100 parts by weight of the monomer. When the addition amount of the chain transfer agent exceeds 5 parts by weight, the polymerization stability of the synthetic resin emulsion is lowered, and the molecular weight of the polymer forming the dispersoid is remarkably lowered, and there is a concern that the physical properties of the emulsion may be lowered. is there.

  The vinyl alcohol polymer (B) containing 1 to 12 mol% of ethylene units in the molecule and blended in the emulsion (A) can be obtained by saponifying a copolymer of vinyl ester and ethylene. it can. It is important to contain 1 to 12 mol% of ethylene units in the molecule, and the amount of ethylene units is preferably 1.5 mol% or more, and more preferably 2 mol% or more. When the ethylene unit content is below this range, as will be apparent from Comparative Example 5 described later, the redispersibility of the emulsion powder decreases, and when the ethylene unit content exceeds this range, the Comparative Example described below. As is apparent from 6 and Comparative Example 9, the redispersibility of the emulsion powder is extremely poor and the film forming property is also poor. In addition, in the case of containing propylene units, the redispersibility of the emulsion powder is poor and the film forming property is also poor, as will be apparent from Comparative Example 10 described later.

The vinyl alcohol polymer (B) containing 1 to 12 mol% of ethylene units has a 1,2-glycol bond (1.7-X when the content of ethylene units is X mol%). / 40) to 4 mol% of a vinyl alcohol polymer is also one of the preferred embodiments of the present invention, and the use of this polymer further improves the redispersibility of the resulting emulsion powder.
As a method for producing this polymer, for example, a method in which vinylene carbonate is copolymerized with vinyl ester monomer and ethylene so as to have the above 1,2-glycol bond amount, and ethylene and vinyl ester monomer are copolymerized. In this case, the polymerization temperature may be higher than normal conditions, for example, 75 to 200 ° C., and polymerization may be performed under pressure. In the latter method, the polymerization temperature is not particularly limited, but is usually 95 to 190 ° C, preferably 100 to 160 ° C.

  In this case, the content of 1,2-glycol bond is preferably (1.7-X / 40) mol% or more, more preferably (1.75-X / 40) mol% or more, optimally. Is (1.8-X / 40) mol% or more. The 1,2-glycol bond content is preferably 4 mol% or less, more preferably 3.5 mol% or less, and most preferably 3.2 mol% or less. Here, the content of 1,2-glycol bonds can be determined from analysis of NMR spectra.

  The degree of polymerization of the vinyl alcohol polymer (B) may be selected according to various situations and is not particularly limited, but is usually preferably 100 to 3000 from the viewpoint of workability during powderization, Preferably it is 150-2000, More preferably, it is 200-1600, Optimally, it is 200-1000. On the other hand, the saponification degree of the vinyl alcohol polymer (B) is not particularly limited, but is preferably 70 to 99 mol%, more preferably 75 to 98 mol%, and further preferably 80 to 96 mol%.

  The vinyl alcohol polymer (B) may be a copolymer of an ethylenically unsaturated monomer that can be copolymerized within a range that does not impair the effects of the present invention. Examples of such ethylenically unsaturated monomers include acrylic acid, methacrylic acid, fumaric acid, (anhydrous) maleic acid, itaconic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, trimethyl- (3-acrylamide). -3-dimethylpropyl) -ammonium chloride, acrylamido-2-methylpropanesulfonic acid and its sodium salt, ethyl vinyl ether, butyl vinyl ether, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene N-vinyl amides such as sodium vinyl sulfonate, sodium allyl sulfonate, N-vinyl pyrrolidone, N-vinyl formamide, N-vinyl acetamide, etc. Le% following can be used. In addition, a terminal modified product obtained by copolymerizing a vinyl ester monomer such as vinyl acetate with ethylene in the presence of a thiol compound such as thiol acetic acid or mercaptopropionic acid, and saponifying the resulting copolymer. It can also be used.

  The compounding ratio of the vinyl alcohol polymer (B) to be blended with the synthetic resin emulsion (A) is such that the vinyl alcohol polymer (B) 1 is 100 parts by weight of the solid content (dispersoid) of the synthetic resin emulsion (A). It is suitable that it is -50 weight part, More preferably, it is 3-30 weight part, More preferably, it is 5-20 weight part, Furthermore, it is 7-20 weight part. When the vinyl alcohol polymer (B) is less than 1 part by weight, there is a concern that the redispersibility after pulverization is lowered, and the mechanical stability when the emulsion powder is mixed with a hydraulic substance is insufficient. There is a concern that the dispersibility in a hydraulic substance may be reduced. On the other hand, when the amount exceeds 50 parts by weight, there is a concern that physical properties such as water resistance of the obtained emulsion powder are lowered and the strength of the hydraulic substance using the emulsion powder is lowered.

The synthetic resin emulsion powder of the present invention is obtained by blending the above-mentioned synthetic resin emulsion (A) with the vinyl alcohol polymer (B) and then drying, preferably spray drying. For spray drying, normal spray drying in which a fluid is sprayed to dry can be used. Depending on the type of spraying, there are disc type, nozzle type, shock wave type, etc. Any method may be used. Moreover, hot air, heating steam, etc. are used as a heat source. The drying conditions may be appropriately selected depending on the size and type of the spray dryer, the concentration, viscosity, flow rate, etc. of the synthetic resin emulsion. The drying temperature is suitably from 100 ° C to 150 ° C, and it is desirable to set other drying conditions so that a sufficiently dried powder can be obtained within this drying temperature range.
As a method for adding the vinyl alcohol polymer (B), a method in which an aqueous solution of the vinyl alcohol polymer (B) is added to the emulsion (A) is a suitable method, but the vinyl alcohol polymer (B). The method of adding the powder, flakes or pellets of (1) to the emulsion (A) is also mentioned. Moreover, when manufacturing emulsion (A) by emulsion polymerization, the method of adding a vinyl alcohol polymer (B) (lump or continuous addition) to the latter half of emulsion polymerization is also mentioned.

  Moreover, it is desirable to use inorganic powder (antiblocking agent) for the purpose of improving the storage stability and redispersibility in water of the synthetic resin emulsion powder of the present invention. The inorganic powder may be added to the emulsion powder after spray drying and mixed uniformly. However, when the synthetic resin emulsion is sprayed in the presence of the inorganic powder during spray drying (simultaneous spraying), uniform mixing is performed. This is preferable. The inorganic powder is preferably fine particles having an average particle size of 0.1 to 100 μm. As the inorganic powder, fine inorganic powder is preferable, and calcium carbonate, clay, anhydrous silicic acid, aluminum silicate, white carbon, talc, alumina white and the like are used. Of these inorganic powders, anhydrous silicic acid is preferred. The amount of the inorganic powder used is preferably 20% by weight or less, more preferably 10% by weight or less, based on the performance, in view of performance. The lower limit is preferably 0.1% by weight or more, and more preferably 0.2% by weight or more. Organic fillers can also be used.

  The synthetic resin emulsion powder of the present invention has a dissolution rate when the film formed at 20 ° C. after re-dispersion in water has little elution into water, particularly when the film is immersed in water at 20 ° C. for 24 hours. When it is 7% or less, it has better redispersibility and water resistance, and when mixed with a hydraulic substance such as cement mortar, the strength of the obtained hydraulic substance can be further improved. To preferred. A more preferable elution rate is 6% or less.

  In order to further improve the redispersibility of the synthetic resin emulsion powder in water, various water-soluble additives can be added. The additive is preferable because it is uniformly mixed when added to the synthetic resin emulsion before spray drying and spray dried. The amount of the water-soluble additive used is not particularly limited, and is appropriately controlled to such an extent that it does not adversely affect physical properties such as water resistance of the emulsion. Examples of such additives include hydroxyethyl cellulose, methyl cellulose, starch derivatives, polyvinyl pyrrolidone, polyethylene oxide, etc., water-soluble alkyd resins, water-soluble phenol resins, water-soluble urea resins, water-soluble melamine resins, water-soluble naphthalene sulfonic acids Examples include resins, water-soluble amino resins, water-soluble polyamide resins, water-soluble acrylic resins, water-soluble polycarboxylic acid resins, water-soluble polyester resins, water-soluble polyurethane resins, water-soluble polyol resins, and water-soluble epoxy resins.

The synthetic resin emulsion powder of the present invention (average particle diameter of 1 to 1000 μm, preferably 2 to 500 μm) can be used as it is for various applications as it is, but is conventionally known as long as it does not impair the effects of the present invention. These various emulsions and emulsion powders can also be added and used.
The synthetic resin emulsion powder of the present invention is particularly useful as an admixture for hydraulic materials or a joint material for hydraulic materials. Here, examples of the hydraulic substance include hydraulic cements such as Portland cement, alumina cement, slag cement and fly ash cement, and hydraulic materials other than cement such as gypsum and plaster.
When the above-mentioned admixture for a hydraulic substance is used by blending it in a cement mortar composed of cement, aggregate and water, for example, the blending quantity of the admixture for hydraulic substance is 5 to 20% by weight with respect to the cement. Is preferred. Here, examples of the aggregate include fine aggregates such as river sand, crushed sand, colored sand and silica sand, and coarse aggregates such as river gravel and crushed stone.
When the synthetic resin emulsion powder of the present invention is used as a joining material for hydraulic substances, the synthetic resin emulsion powder is appropriately re-emulsified with water, and water such as concrete is used as the joining material (primer treatment material). The construction is carried out by applying to a hard substance substrate and then applying a hydraulic substance such as cement mortar. By using such a joining material, it is possible to impart excellent adhesion and durability, and excellent mechanical strength.

In order to further improve the dispersibility of the admixture for hydraulic substance and the joining material, various additives can be added. The additive is preferable because it is uniformly mixed when added to the synthetic resin emulsion before spray drying and spray dried. The amount of the water-soluble additive used is not particularly limited, and is appropriately controlled to such an extent that it does not adversely affect physical properties such as water resistance of the emulsion. Examples of such additives include hydroxyethyl cellulose, methyl cellulose, starch derivatives, polyvinyl pyrrolidone, polyethylene oxide, etc., water-soluble alkyd resins, water-soluble phenol resins, water-soluble urea resins, water-soluble melamine resins, water-soluble naphthalene sulfonic acids. Examples include resins, water-soluble amino resins, water-soluble polyamide resins, water-soluble acrylic resins, water-soluble polycarboxylic acid resins, water-soluble polyester resins, water-soluble polyurethane resins, water-soluble polyol resins, and water-soluble epoxy resins.
The hydraulic material admixture and jointing material of the present invention include AE agent, water reducing agent, fluidizing agent, water retention agent, thickening agent, waterproofing agent, water proofing agent, etc. for use as an admixture for cement and mortar. A foaming agent etc. are used suitably.
The synthetic resin emulsion powder of the present invention can also be used for applications such as adhesives, paints and paper processing agents. For these uses, viscosity improvers, water retention agents, tackifiers, thickeners, pigment dispersants, stabilizers, and the like are used as appropriate.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” and “%” mean weight basis.
Emulsion production example 1
A pressure-resistant autoclave equipped with a nitrogen inlet, a thermometer, and a stirrer was charged with 80 parts of a 9.5% aqueous solution of PVA-217 (manufactured by Kuraray Co., Ltd., polymerization degree 1700, saponification degree 88 mol%), and the temperature was raised to 60 ° C. After warming, nitrogen substitution was performed. After charging 80 parts of vinyl acetate, ethylene was pressurized to 4.9 MPa, and 2 g of 0.5% hydrogen peroxide aqueous solution and 0.3 g of 2% Rongalite aqueous solution were injected to initiate polymerization. When the residual vinyl acetate concentration reached 10%, ethylene was released, the ethylene pressure was set to 2.0 MPa, and 0.3 g of 3% hydrogen peroxide aqueous solution was injected to complete the polymerization. There was no aggregation during the polymerization and the polymerization stability was excellent, and an ethylene-vinyl acetate copolymer emulsion (Em-1) having a solid content concentration of 55% and an ethylene content of 18% by weight was obtained.

Emulsion production example 2
In a glass container equipped with a reflux condenser, a dropping funnel, a thermometer, a nitrogen inlet, and a stirrer, PVA having a mercapto group at the end (polymerization degree 550, saponification degree 88.3 mol%, mercapto group content 3.3) × 10 ⁻⁵ equivalent / g) 5 parts and 90 parts of ion-exchanged water were charged and completely dissolved at 95 ° C. Next, after adjusting the pH to 4 with dilute sulfuric acid, 10 parts of methyl methacrylate, 10 parts of n-butyl acrylate and 0.1 part of n-dodecyl mercaptan were added while stirring at 150 rpm, and the temperature was raised to 70 ° C. after nitrogen substitution. . Polymerization was started by adding 5 parts of 1% potassium persulfate, and a mixture of 40 parts of methyl methacrylate, 40 parts of n-butyl acrylate and 0.4 part of n-dodecyl mercaptan was continuously added over 2 hours. . Three hours after the start of the polymerization, the conversion was 99.5% and the polymerization was terminated. A stable methyl methacrylate / n-butyl acrylate copolymer emulsion (Em-2) having a solid content concentration of 52.0% was obtained.

Emulsion production example 3
Instead of PVA having a mercapto group at the terminal in Emulsion Production Example 2 (polymerization degree 550, saponification degree 88.3 mol%, mercapto group content 3.3 × 10 ⁻⁵ equivalent / g), it has a mercapto group at the terminal Except for using PVA (ethylene content 0.5 mol%, polymerization degree 550, saponification degree 88.3 mol%, mercapto group content 3.3 × 10 ⁻⁵ eq / g), the same as in Emulsion Production Example 2 was used. Thus, an emulsion (Em-3) was obtained.

  100 parts of ethylene-vinyl acetate copolymer emulsion (A) (Em-1) solid content obtained in Emulsion Production Example 1 and ethylene-modified PVA (B) (PVA-1, ethylene unit content 5 mol%, polymerization degree 500) , Saponification degree 95 mol%) 200% 5% aqueous solution mixed with 2% silicic anhydride fine powder (average particle size 2 μm) separately in hot air at 120 ° C. Spraying and drying were performed to obtain an emulsion powder having an average particle size of 20 μm.

(Emulsion powder performance evaluation)
100 parts of ion-exchanged water at 20 ° C. was added to 100 parts of the emulsion powder and sufficiently stirred with a stirrer, and the following physical properties were evaluated. The results are shown in Table 1.
-Redispersibility: The redispersed emulsion was filtered through a 200 mesh stainless steel wire mesh, the filtration residue was dried at 105 ° C for 5 hours, and the ratio of the filtration residue was measured.
Filtration residue (%) = (filter residue after drying / emulsion powder weight used for redispersion) × 100
The smaller the filtration residue, the more a hydraulic product with superior strength is obtained when the emulsion powder is used as an admixture or jointing material for hydraulic materials. According to the present invention, an emulsion powder having a filtration residue of 5% or less (Table 1) can be obtained.
-State after re-dispersion: The state of the re-dispersed emulsion was observed visually and with an optical microscope, and judged according to the following criteria.
◎ Uniform redispersion with an average particle size of 50 μm or less ○ Uniform redispersion with no undispersed matter
Δ: Redispersed, but undispersed material is observed.
X Not redispersed / Film-forming property: The re-dispersed material was cast and dried on a glass plate at 50 ° C., and the film-forming property was judged according to the following criteria.
○ A uniform film is obtained and a tough film is obtained.
△ Although it becomes a film, it is fragile.
X A uniform film cannot be obtained.
Water resistance (elution rate of film in water): The redispersed emulsion was formed at 20 ° C. to obtain a film (film thickness 100 μm). The film was immersed in 20 ° C. water for 24 hours, and the elution rate was calculated by the following formula.
Elution rate (%) = {1− (absolute dry weight after immersion) / (absolute dry weight of film before immersion)} × 100
Film dry weight before immersion; film weight before immersion (water content)-(film weight before immersion (water content) x film moisture content (%) / 100)
Absolute dry weight of film after immersion; weight of the absolute dry film after immersion at 105 ° C.
The smaller the elution rate, the better the water resistance and redispersibility. According to the present invention, an emulsion powder having an elution rate of 7% or less (Table 1) can be obtained.
Standing stability: The redispersed emulsion was allowed to stand at 20 ° C. and 0 ° C., and the state was observed after 1 week, and judged according to the following criteria.
○ No change,
△ Thickening is observed,
× Gelled gel content:
An emulsion obtained by redispersion in water at 20 ° C. (redispersion at a ratio of 100 parts of emulsion powder to 100 parts of ion-exchanged water at 20 ° C.) was cast on a PET film at 20 ° C. and 65% RH, The film was dried for 7 days to obtain a dry film having a thickness of 500 μm. A sample obtained by punching this film to a diameter of 2.5 cm was subjected to Soxhlet extraction with acetone for 24 hours, followed by extraction for 24 hours in boiling water, and the insoluble content (gel content) of the film after extraction was determined.
Gel content (%) = absolute dry weight of film after extraction / absolute dry weight of film before extraction × 100
Film absolute dry weight before extraction = film weight before extraction (water content) − {film weight before extraction (water content) × water content of film (%) / 100}
* Moisture content of the film: The film (a sample different from the sample extracted with acetone and boiling water) is completely dried at 105 ° C. for 4 hours, and the moisture content of the film is obtained in advance.
* Extra dry weight of the film after extraction: The weight of the dry film after extraction at 105 ° C. for 4 hours.
The larger the gel content, the more vinyl alcohol polymer (B) is grafted onto the dispersoid (polymer), and the redispersibility of the emulsion powder is further improved. According to the present invention, an emulsion powder having a gel content of 20% or more (Table 1) can be obtained.

  In Example 1, instead of ethylene-modified PVA (B) (PVA-1), ethylene-modified PVA (B) (PVA-2, ethylene unit content 10 mol%, polymerization degree 500, saponification degree 98 mol%) was used. An emulsion powder was obtained in the same manner as in Example 1 except that it was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  In Example 1, instead of ethylene-modified PVA (B) (PVA-1), ethylene-modified PVA (B) (PVA-3, ethylene unit content 5 mol%, polymerization degree 500, saponification degree 88 mol%) was used. An emulsion powder was obtained in the same manner as in Example 1 except that it was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 1
In Example 1, instead of ethylene-modified PVA (B) (PVA-1), unmodified PVA (B) (PVA-4, Kuraray Co., Ltd. PVA-105, polymerization degree 500, saponification degree 98.5 mol) %) Was used in the same manner as in Example 1 to obtain an emulsion powder. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 2
In Example 1, instead of ethylene-modified PVA (B) (PVA-1), unmodified PVA (B) (PVA-5, PVA-205 manufactured by Kuraray Co., Ltd., polymerization degree 500, saponification degree 88 mol%) An emulsion powder was obtained in the same manner as in Example 1 except that was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 3
In Example 1, an emulsion powder was obtained in the same manner as in Example 1 except that ethylene-modified PVA (B) (PVA-1) was not used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  In Example 1, instead of ethylene-modified PVA (B) (PVA-1), ethylene-modified PVA (B) (PVA-6, ethylene unit content 5 mol%, polymerization degree 1300, saponification degree 93 mol%) was used. An emulsion powder was obtained in the same manner as in Example 1 except that it was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 4
In Example 1, instead of ethylene-modified PVA (B) (PVA-1), unmodified PVA (B) (PVA-7, PVA-613 manufactured by Kuraray Co., Ltd., polymerization degree 1300, saponification degree 95 mol%) An emulsion powder was obtained in the same manner as in Example 1 except that was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  An emulsion powder was obtained in the same manner as in Example 1 except that 100 parts of a 5% aqueous solution of ethylene-modified PVA (B) (PVA-1) was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  An emulsion powder was obtained in the same manner as in Example 1 except that 300 parts of a 5% aqueous solution of ethylene-modified PVA (B) (PVA-1) was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  An emulsion powder was obtained in the same manner as in Example 1 except that 40 parts of a 5% aqueous solution of ethylene-modified PVA (B) (PVA-1) was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  An emulsion powder was obtained in the same manner as in Example 1 except that 500 parts of a 5% aqueous solution of ethylene-modified PVA (B) (PVA-1) was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  In Example 1, instead of ethylene-modified PVA (B) (PVA-1), ethylene-modified PVA (B) (PVA-8, ethylene unit content 2.5 mol%, polymerization degree 500, saponification degree 88 mol%) An emulsion powder was obtained in the same manner as in Example 1 except that was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  In Example 1, instead of ethylene-modified PVA (B) (PVA-1), ethylene-modified PVA (B) (PVA-9, ethylene unit content 1.5 mol%, polymerization degree 500, saponification degree 88 mol%) An emulsion powder was obtained in the same manner as in Example 1 except that was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 5
In Example 1, instead of ethylene-modified PVA (B) (PVA-1), ethylene-modified PVA (B) (PVA-10, ethylene unit content 0.5 mol%, polymerization degree 500, saponification degree 95 mol%) An emulsion powder was obtained in the same manner as in Example 1 except that was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 6
In Example 1, instead of ethylene-modified PVA (B) (PVA-1), ethylene-modified PVA (B) (PVA-11, ethylene unit content 25 mol%, polymerization degree 500, saponification degree 95 mol%) was used. The emulsion was pulverized in the same manner as in Example 1 except that it was used. However, when the PVA was made into an aqueous solution, it became cloudy violently and was not completely dissolved. The cloudy liquid was blended into the emulsion, and the physical properties of the emulsion powder obtained in the same manner as in Example 1 were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  In Example 1, instead of ethylene-modified PVA (B) (PVA-1), ethylene-modified PVA (B) obtained by high temperature polymerization (PVA-12, ethylene unit content 3 mol%, 1,2-glycol bond) An emulsion powder was obtained in the same manner as in Example 1 except that the amount was 1.9 mol%, the degree of polymerization was 1300, and the degree of saponification was 93 mol%. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  In Example 1, instead of ethylene-modified PVA (B) (PVA-1), ethylene-modified PVA (B) obtained by high-temperature polymerization (PVA-13, ethylene unit content 5 mol%, 1,2-glycol bond) An emulsion powder was obtained in the same manner as in Example 1 except that the amount was 2.2 mol%, the degree of polymerization was 500, and the degree of saponification was 88 mol%. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

  An emulsion was prepared in the same manner as in Example 1 except that the methyl methacrylate / n-butyl acrylate copolymer emulsion (A) (Em-2) prepared in Emulsion Production Example 2 was used instead of Em-1. A powder was obtained. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 7
In Example 13, an emulsion powder was obtained in the same manner as in Example 1 except that unmodified PVA (B) (PVA-5) was used instead of ethylene-modified PVA (B) (PVA-1). The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 8
In Comparative Example 1, an emulsion powder was obtained in the same manner as in Comparative Example 1, except that Em-3 was used instead of Em-1. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 9
In Example 1, instead of ethylene-modified PVA (B) (PVA-1), ethylene-modified PVA (B) (PVA-14, ethylene unit content 15 mol%, polymerization degree 1300, saponification degree 93 mol%) was used. The emulsion was pulverized in the same manner as in Example 1 except that it was used. However, when the PVA was made into an aqueous solution, it became cloudy and was not completely dissolved. The cloudy liquid was blended into the emulsion, and the physical properties of the emulsion powder obtained in the same manner as in Example 1 were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Comparative Example 10
In Example 1, instead of ethylene-modified PVA (B) (PVA-1), propylene-modified PVA (B) (PVA-15, propylene unit content 5 mol%, polymerization degree 1300, saponification degree 93 mol%) was used. The emulsion was pulverized in the same manner as in Example 1 except that it was used. The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

In emulsion production example 1, instead of “PVA217” manufactured by Kuraray Co., Ltd., PVA obtained by high-temperature polymerization (1,2-glycol bond amount 2.2 mol%, polymerization degree 1700, saponification degree 88 mol%) was used. Except that, an ethylene-vinyl acetate copolymer emulsion (Em-4) having a solid content of 55% and an ethylene content of 18% by weight was obtained in the same manner as in Emulsion Production Example 1.
Next, an emulsion powder was obtained in the same manner as in Example 1, except that Em-4 was used instead of the ethylene-vinyl acetate copolymer emulsion (A) (Em-1). . The physical properties of the obtained emulsion powder were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

Next, the emulsion powders obtained in Examples 1 to 14 and Comparative Examples 1 to 10 were used as hydraulic material admixtures and hydraulic material joining materials, and physical properties were evaluated. The results are shown in Tables 2-3.
(Performance evaluation of admixtures for hydraulic materials)
Performance as an admixture for cement mortar Properties test of cement mortar 1) Mortar composition:
Hydraulic material admixture / cement weight ratio = 0.10
Sand / cement weight ratio = 3.0, water / cement weight ratio = 0.6
2) Slump value: Measured according to JIS A-1173
(Indicator of dispersibility in cement mortar)
3) Bending strength: measured according to JIS A-6203 4) Compressive strength: measured according to JIS A-6203

Moreover, 100 parts of ion-exchanged water was added to 100 parts of the admixture for hydraulic substance, and the mixture was sufficiently stirred with a stirrer to evaluate the following physical properties. The results are shown in Tables 1-2.
Water resistance (elution rate of film in water): The redispersed emulsion was formed at 20 ° C. to obtain a film (film thickness 100 μm). The film was immersed in 20 ° C. water for 24 hours, and the elution rate was calculated by the following formula.
Elution rate (%) = {1− (absolute dry weight after immersion) / (absolute dry weight before immersion)} × 100
* Absolute dry weight before immersion; film weight before immersion (moisture content)-(film weight before immersion (water content) x film moisture content (%) / 100)
* Absolute dry weight after immersion: Weight obtained by absolute drying of the immersed film at 105 ° C.
(Performance evaluation of joint material for hydraulic materials)
Performance as a joining material for cement mortar Next, the following tests were performed using the emulsion powders obtained in Examples 1 to 14 and Comparative Examples 1 to 10 as they were as joining materials.
Adhesive strength test 1) Test substrate As a concrete substrate used for the test, 300 parts of Portland cement, 800 parts of silica sand, 1000 parts of coarse aggregate (ballast) and 180 parts of water, which are standard blends in architecture, are mixed. Then, it was cast in a size of 300 mm × 300 mm × thickness 50 mm with a plywood mold and cured for 28 days in a test room {temperature 20 ° C., relative humidity (RH) 65%}.
2) Coated mortar The composition of the coated mortar used in the test is cement 1 and aggregate (standard sand) 2 by weight ratio, and the water-cement ratio is adjusted so that the flow value becomes 170 ± 5. It knead | mixed according to prescription | regulation of 9.4 of R5201.
In addition, the normal Portland cement prescribed | regulated to JISR5210 (Portland cement) was used as a cement, and the Toyoura standard sand prescribed | regulated to 9.2 of JISR5210 was used as an aggregate.

3) Method for preparing test body The joint material was uniformly applied to the surface of the test substrate of 1) with a brush, and left in an atmosphere of a temperature of 20 ° C. and 65% RH for 24 hours. The application amount of the joining material was 50 g / m ² as a solid content. Next, apply the mortar of 2) above with a gold trowel so that the thickness is 6 mm, and after curing in an atmosphere of 20 ° C. and 80% RH or more for 48 hours, further curing in the test room for 26 days. A test body was obtained.
4) Bond strength test in standard state After the mortar surface of the specimen prepared in 3) above was cut into a size of 40 mm × 90 mm until reaching the substrate, the bond strength was measured according to the test method specified in 5.6 of JIS A6916. The test was performed and the average value of the measured values at five locations was obtained.

5) Cold and hot resistance test (durability test)
Irradiation with an infrared lamp for 105 minutes and subsequent watering for 15 minutes were continued for 300 cycles so that the surface temperature of the test specimen prepared in 3) was 70 ° C. However, the water temperature was 15 ± 5 ° C., and the amount of water sprayed per specimen was 6 liters per minute. After 300 cycles, the specimen was left in the standard state for 24 hours, and the test was conducted in the same manner as in 4) above.

6) Freeze-thaw resistance test (durability test)
The specimen prepared in 3) above is immersed in 20 ± 3 ° C. water for 15 hours, immersed in a −20 ± 3 ° C. constant temperature bath for 3 hours, and then immersed in a 70 ± 3 ° C. constant temperature bath for 6 hours. This was regarded as one cycle and continued for 50 cycles. After 50 cycles, the specimen was left in the standard state for 24 hours, and the test was conducted in the same manner as in 4) above.

According to the present invention, a synthetic resin emulsion powder having excellent redispersibility, water resistance, film forming property when redispersed and excellent standing stability at low temperature can be obtained. By using the powder, it is possible to obtain an admixture for a hydraulic substance that is excellent in dispersibility in a hydraulic substance such as cement mortar and that is excellent in strength of the obtained hydraulic substance. Moreover, by using the emulsion powder of the present invention, a joining material for a hydraulic substance that is excellent in adhesiveness and durability and also excellent in mechanical strength can be obtained.

Claims (10)

An emulsion having a vinyl alcohol polymer as a dispersant and a polymer having one or more unsaturated monomer units selected from ethylenically unsaturated monomers and diene monomers as a dispersoid (A ) And a synthetic resin emulsion powder obtained by drying a composition comprising a vinyl alcohol polymer (B) containing 1 to 12 mol% of ethylene units in the molecule. The synthetic resin emulsion powder according to claim 1, wherein the ethylene unit content is 1.5 to 12 mol%. The synthetic resin emulsion powder according to claim 1 or 2, wherein the ethylene unit content is 2 to 12 mol%. The vinyl alcohol polymer (B) containing 1 to 12 mol% of ethylene units is blended in an amount of 1 to 50 parts by weight per 100 parts by weight of the solid content of the emulsion (A). Synthetic resin emulsion powder. The polymer having one or more unsaturated monomer units selected from ethylenically unsaturated monomers and diene monomers is a vinyl ester polymer or an olefin-vinyl ester copolymer. The synthetic resin emulsion powder in any one of Claims 1-4. When the vinyl alcohol polymer (B) containing 1 to 12 mol% of ethylene units has an ethylene unit content of X mol%, 1,2-glycol bonds (1.7-X / 40) to The synthetic resin emulsion powder according to any one of claims 1 to 5, which is a vinyl alcohol polymer containing 4 mol%. The synthetic resin powder according to any one of claims 1 to 6, wherein the vinyl alcohol polymer of the dispersant is a vinyl alcohol polymer having a 1,2-glycol bond of 1.9 mol% or more. The synthetic resin powder according to any one of claims 1 to 7, wherein the drying is spray drying. The synthetic resin emulsion powder shows an elution rate of 7% or less when the film formed at 20 ° C is immersed in 20 ° C water for 24 hours after the powder is re-dispersed in water. The synthetic resin emulsion powder in any one. The synthetic resin emulsion powder according to any one of claims 1 to 9, wherein the synthetic resin emulsion powder contains an inorganic powder.