JPH04139046A - Powdery dispersant and its production - Google Patents

Abstract

PURPOSE:To obtain a dispersant having satisfactory dispersing property and capable of being stored over a long period of time by spray-drying a mixture of a synthetic resin emulsion and/or synthetic rubber latex with an anti-caking material contg. cement hydrate as an essential component. CONSTITUTION:An anti-caking material contg. a hydraulic substance and/or cement hydrate of 0.005-50mum average particle diameter as an essential component is prepd. and 31-99 pts.wt. of the anti-caking material and 100 pts.wt. (expressed in terms of solid matter) synthetic resin emulsion and/or synthetic rubber latex are introduced into a spray drying tower and spray-dried to produce a powdery dispersant.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a powdered dispersant with improved dispersibility and a method for producing the same. A wide variety of products including superior concrete, repair materials, flooring materials, waterproofing materials, adhesives, and building materials.

(Prior art and its problems) Conventionally, synthetic resin emulsions and/or synthetic rubber latexes have been mixed with cement, aggregate, water, etc. to improve crack resistance, bending strength, impact resistance, and adhesive properties of mortar, etc. It is known to be used in highly durable mortar etc. (New Cement and Concrete, Published June 25, 1975 by Kensetsu General Materials Co., Ltd.).

In addition, a composition consisting of cement, water, synthetic resin emulsion, etc. can be mixed at 1500 kgf/
A method of obtaining a bending strength of cm'' or more is also known (Japanese Patent Publication No. 63-386).

Furthermore, it is also known to obtain building materials and the like by bonding and curing synthetic hydrates with synthetic resin emulsions.

However, when synthetic resin emulsion and/or synthetic rubber latex are mixed with cement, a hydration reaction occurs and hardens, so the only way to do this is to mix it on-site. In such cases, synthetic resin emulsion and synthetic rubber latex are dispersed in an aqueous system, so there are problems such as increased transportation costs due to their liquid state and the possibility of on-site measurement errors. It has been desired to develop a powdery dispersant containing an emulsion and/or a synthetic rubber latex with good dispersibility.

Under these circumstances, various studies have been made on methods for obtaining powdery dispersants with good dispersibility. For example, as a method for obtaining a redispersible powder of a synthetic resin emulsion such as ethylene/vinyl acetate copolymer, 5 to 20 parts by weight of polyvinyl alcohol is added as a protective colloid to 100 parts by weight of the polymer, and The aqueous dispersion of the resulting copolymer is spray-dried, with an average particle size of 0. An aqueous dispersion of dried anti-caking materials such as aluminum silicate, silica, and calcium carbonate having an O of 1 to 0.5μ is added to a spray drying tower at a ratio of 3 to 30 parts by weight based on 100 parts by weight of the solid content of the aqueous dispersion. There is a known method of introducing these separately and spraying them at the same time (Japanese Patent Publication No. 55-50971).

However, in these methods, the amount of polyvinyl alcohol added as a protective colloid is as large as 5 to 20 parts by weight, making it impossible to maintain a high concentration of the ethylene/vinyl acetate copolymer itself in the solid content of the synthetic resin emulsion. The average particle size of There are restrictions such as being limited to O1 to 0.5μ, and the performance of the ethylene/vinyl acetate copolymer cannot be fully exhibited.

The present inventors conducted various studies to solve the above problems, and found that a specific amount of an anti-caking material containing a hydraulic substance and/or hydrate with an average particle size of 0.005 to 50μ as an essential component, The present invention was completed based on the knowledge that a powdery dispersant with good dispersibility can be provided by introducing it into a spray drying tower together with a synthetic resin emulsion and/or synthetic rubber latex and spray drying it.

(Means for Solving the Problem) That is, the present invention provides a synthetic resin emulsion and/or synthetic rubber latex with a solid content of 100 parts by weight and an average particle size of o.
It is a powder dispersant consisting of 31 to 99 parts by weight of an anti-caking agent containing a hydraulic substance of oos ~ 50μ and/or a cement-based hydrate as an essential component, and is a powdery dispersant consisting of a synthetic resin emulsion and/or a solid of synthetic rubber latex. Anti-caking material 3 containing 100 parts by weight as essential components and a hydraulic substance and/or cement-based hydrate with an average particle size of 0.005 to 50μ
1 to 99 parts by weight of the powdered dispersant is introduced into a spray drying tower and spray-dried.

The present invention will be explained in detail below.

The synthetic resin emulsion according to the present invention refers to vinyl polymers, and examples include acrylic polymers, vinyl acetate polymers, vinylidene chloride polymers, and vinyl chloride polymers, and it is naturally possible to copolymerize one or more of these polymers. be.

Specific examples of copolymers include vinylidene chloride (
PVDC)/butyl acrylate (BA) copolymer, ethylene (E)/vinyl acetate (VAc) copolymer (EVA)
) and vinyl acetate/vinyl versatate (Veova
) copolymers, etc. Among these, vinyl acetate is particularly preferred from the viewpoint of adhesive strength with concrete.

Further, in order to improve the weather resistance, alkali resistance and water resistance of the vinyl acetate synthetic resin, it is preferable to copolymerize other comonomers.

These comonomers include cyanated vinyl monomers such as ethylene, acrylonitrile, and methacrylate trile; unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, and crotonic acid; and furthermore, methyl acrylate, ethyl acrylate, Acrylic acid ester monomers such as butyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, hydroxyethyl acrylate and glycidyl acrylate, as well as methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate and glycidyl methacrylate. Monomers, furthermore vinyl ether monomers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether and phenyl vinyl ether, furthermore amide monomers such as acrylamide and methacrylamide, furthermore maleimide, N-methylmaleimide and N-ethylmaleimide. , N
-propylmaleimide, N-phenylmaleimide and N
-) Maleimide monomers such as ruylmaleimide, and halogenated olefin monomers such as vinyl chloride and vinylidene chloride, as well as divinylbenzene, ethylene glycol dimethacrylate, 1,3-butylene gelicold dimethacrylate, and 1,4-butylene. Glycol dimethacrylate, propylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, ethylene glycol diacrylate, polyethylene glycol diacrylate, triallyl cyanurate, triallyl isocyanurate, trimethylolpropane trimethacrylate,
Examples include polyfunctional vinyl monomers such as allyl acrylate, allyl methacrylate, vinyl acrylate, and vinyl methacrylate.

The amount of these copolymerizable comonomers used is at most 50 parts by weight per 100 parts by weight of vinyl acetate and comonomers in total. If the amount exceeds 50 parts by weight, it becomes difficult to obtain the excellent adhesive properties inherent to vinyl acetate.

Note that it is also possible to copolymerize vinyl acetate by combining these copolymerizable comonomers.

In particular, a synthetic resin emulsion prepared by copolymerizing 20 to 80 parts by weight of acrylics such as ethyl acrylate, butyl acrylate, and ethylhexyl acrylate with a total of 100 parts by weight of vinyl acetate and a comonomer was spray-dried together with an anti-caking material. The powdered dispersant provides good fluidity when mixed with hydraulic cement and water.

The synthetic rubber latex according to the present invention is a synthetic rubber compound synthesized from diene monomers, and includes styrene/butadiene copolymer (SB), acrylonitrile/butadiene copolymer (NB), methyl methacrylate/butadiene copolymer (NB), and methyl methacrylate/butadiene copolymer (NB). MB), polybutadiene, polychloroprene, and the like.

In the present invention, when obtaining a synthetic resin emulsion and/or a synthetic rubber latex (hereinafter referred to as a polymer), a surfactant is used as an emulsion stabilizer, and a water-soluble oligomer formed during the polymerization process acts as an emulsion stabilizer. It is effective to increase the concentration of the polymerization initiator.

These surfactants include sodium vinyl sulfonate,
Anionic surfactants such as 2-sulfoethyl methacrylate soda, allyl alkyl sulfosuccinate sodium salt, higher alcohol sulfate ester sodium salt and polyoxyethylene alkylphenyl ether sulfate ammonium salt, 2-aminoethyl methacrylate hydrochloride and 2-hydroxy-3 -Cationic surfactants such as trimethylaminopropyl methacrylide chloride and nonionic surfactants such as polyoxyethylene condensates, polyoxyethylene polyoxypropylene ethers and polyoxyethylene alkylphenyl ethers.

The amount of surfactant used is preferably about 0.1 to 10 parts by weight based on 100 parts by weight of solid content of the polymer.

If it is less than 0.1 part by weight, it is difficult to carry out emulsion polymerization, and if it exceeds 10 parts by weight, it tends to adversely affect the weather resistance, alkali resistance, water resistance, etc. of these polymers.

In addition, as a polymerization initiator, persulfates such as potassium persulfate as an electrolytic group, 4,4'-azobis-cyanovaleric acid having a carboxyl group, and 2,2'-azobisisobutyramidine having an amino group are used. Examples include salt.

The amount of the polymerization initiator used is preferably about 0.1 to 1 part by weight based on 100 parts by weight of the solid content of the polymer.

If it is less than 0.1 part by weight, it is difficult to carry out emulsion polymerization, and if it exceeds 1 part by weight, it tends to have an adverse effect on the weather resistance, alkali resistance, water resistance, etc. of these synthetic resin emulsions and/or synthetic rubber latexes. be.

The particle size of the synthetic resin emulsion and/or synthetic rubber latex thus obtained is preferably about 0.05 to 5 μm.

In order to make the polymer obtained as described above into a redispersible powder, it is dried and powdered together with an anti-caking material by a spray drying method.

The particle size of the anti-caking material according to the present invention has an average particle size of 0.
The essential components are a hydraulic substance and/or a cement hydrate having a diameter of 0.005 to 50 μm.

As the hydraulic substance used in the present invention, hydraulic cement substances, chemical admixtures, and ultrafine powders can be used.

Common hydraulic cement materials include hydraulic lime, Roman cement, natural cement, super fast hardening cement, and alumina cement, as well as normal, moderate heat, early strength, super early strength, low heat,
Various types of Portland cement such as sulfate-resistant, high iron oxide type and white, and these Portland cements include blast furnace slag,
Examples include various mixed cements containing silica and fly ash, as well as hydraulic cement materials such as main solid cement, expansive cement, and colored cements such as white cement.

It is also possible to use a cement containing blast furnace slag or fly ash in a higher amount than a mixed cement such as ordinary blast furnace cement or fly ash cement, and it is also possible to use high sulfate slag cement or improved blast furnace cement.

The particle size of hydraulic cement material is usually 5 to 30 μm, but if it has hydraulic properties, it is 50 μm.
It goes without saying that smaller or larger sizes can also be used within the following range.

Commercially available products of these hydraulic cement substances include ultra-fast hardening cement under the trade name "Onoda Jet Cement" manufactured by Onoda Cement Corporation and "Denka Super Cement" manufactured by Denki Kagaku Kogyo Co., Ltd., and alumina cement under the product name "Denka Super Cement" manufactured by Denki Kagaku Kogyo Co., Ltd. The product names include "Denka Alumina Cement No. 1" and "Denka Alumina Cement No. 2," and examples of ordinary Portland cement include "Ordinary Portland Cement" made by Andes Cement.

In addition, it is also possible to use rapid hardening materials used in ordinary cement concrete, expansive materials such as quicklime, high-strength admixtures such as anhydrous ceracola, and even chemical admixtures such as various slags as hydraulic substances. It is.

As a quick hardening material, Denki Kagaku Kogyo's product name "Denka Atomic" or "Denka Atomic", as an expanding material, Denki Kagaku Kogyo's product name "Denka C3A #20", as a high strength admixture. , Denki Kagaku Kogyo■Product name ``Denka Σ-''
For 1000J and chemical admixtures such as fly ash and slag, Daiichi Cement ■Product name "Cement" and "
Examples include fine ceramics.

These chemical admixtures are usually used with a diameter of 0.5 to 30μ, but it goes without saying that smaller or larger ones within the range of 0.005 to 50μ can also be used.

Furthermore, it is also possible to use ultrafine powder as the hydraulic substance.

The ultrafine powder herein refers to particles that are one order, preferably two orders of magnitude smaller than the hydraulic cement material, and more preferably have an average particle diameter of 1 μm or less. There are no particular restrictions on the ingredients constituting the ultrafine powder, other than the requirement that it be a hydraulic substance, or it is not suitable that it is easily soluble in water.

In addition, the method for producing ultrafine powder is not particularly limited, but any method such as liquid phase, gas phase, pulverization, classification, or a combination thereof may be used, and from the economic point of view, it is preferable to produce it by pulverization or classification. In addition, siliceous dust (which is a by-product of the production of silicon, silicon-containing alloys, and zirconia) is produced by the vapor phase method as a by-product.
Silica hume) and silica dust are effective. In addition, ultrafine powders such as blast furnace slag and fly ash can be used. Commercially available products of these ultrafine powders include "Silica Huyum" manufactured by Nippon Heavy Chemical Industry Co., Ltd. and "Fine Seal" manufactured by Tokuyama Soda Corporation.

Further, ultrafinely pulverized calcium carbonate has been confirmed to have hydraulic properties due to mechanochemical effects, and can also be used.

Cement-based hydrate according to the present invention (hereinafter referred to as hydrated substance)
Examples include hydrates of these hydraulic cement substances, chemical admixtures, and ultrafine powders.

Examples of the hydrated substance include calcium silicate hydrate, calcium aluminate hydrate, calcium aluminate double salt hydrate, ceracola hydrate, alumina sol, and silica sol.

Calcium silicate hydrates include those with sol and/or gel structures obtained as hydraulic cement hydrates, 14A tobermorite obtained by hydrothermally synthesizing quicklime or hydraulic cement materials, and silicic acid, and IIA) bemorite. C5H(I) and C3H(I
I) etc.

As calcium aluminate hydrate, CaO is C,
If Al2O* is A and H2O is H, then C! AI(,
Hydrogarnet, CA, with the chemical composition shown as
H. , C2AH, , C4AH+2, C4AH+2, and the like.

As a double salt hydrate of calcium aluminate, CzA
- Examples include ettringite, which has a chemical composition of 3CaSOm, 32H, and monosulfate, which has a chemical composition of CaA-CaS (L, 12H, and other Ca
A double salt hydrate in which 5Oi is replaced with Ca(OH), etc. can also be used as a hydrated substance.

Hydrates of ceracola include hemihydrate ceracola and trihydrate ceracola.

Examples of sols such as alumina and silica include water glass made of sodium silicate, colloidal silica, alumina sol, and zirconia sol.

As mentioned above, it goes without saying that the particle size of the hydrated substance can be used if it is 0.005 to 50μ. In particular, the average particle size of the gel or sol structure is small, about 0.01 μm.

As described above, it is of course possible to use a combination of the hydraulic cement material, chemical admixture, ultrafine powder, and hydrated material. Particularly, when a hydrate is formed as a slurry and simultaneously sprayed, the hydrated substance may separate and act as an anti-caking agent.

Furthermore, it is effective to reduce the particle size of each of these anti-caking materials to about 5 μm or less by using the ultrafine pulverization technology that has been used recently.

The amount of the anti-caking agent used is 31 to 99 parts by weight based on 100 parts by weight of the solid content of the polymer. If the anti-caking agent is less than 31 parts by weight, it will have little effect as an admixture for hydraulic cement, such as improving fluidity, increasing strength, improving compactness, reducing shrinkage, and improving cracking resistance; if it exceeds 99 parts by weight, The redispersibility of the polymer is poor, and the cracking resistance and adhesiveness are poor.

The powdered dispersant of the present invention can be produced by spray-drying a polymer and an anti-caulking agent.

This spray drying method introduces the anti-caking material at the same time as the polymer. However, the method of introducing the anti-caking material into the spray tower is the Miura body nozzle method, in which each product is introduced into the spray tower in a separately dried form, the method in which the Miura body nozzle is combined, and the method in which the anti-caking material and the polymer are introduced in advance. A method in which a mixed slurry is prepared and the slurry is spray-dried in a spray tower using a Miura body nozzle or a rotating disk.The Miura body nozzle sends out polymer from a central tube, and at the same time sends out powder and compressed air from an outer tube. There is no need to slurry the anti-caking material or polymer in advance, so if the solid content of the polymer is around 50%,
There are advantages such as no need to dilute the polymer and excellent energy efficiency.

The method of combining Miura body nozzles sprays the polymer and anti-caking material simultaneously with separate nozzles, and
This is a method of obtaining a powdery dispersant with good dispersibility by efficiently colliding the two sprays in a drying tower.

When the anti-caking material and the polymer are mixed in advance to form a slurry, it is effective to add water to adjust the viscosity of the mixed slurry.

Air, nitrogen, or the like can be used as the mixed gas used to introduce the anti-caking material and the polymer into the spray drying tower.

Further, the temperature at the tower inlet is preferably about 100-180"C, and preferably about 40-80"C in the cyclone.

When carrying out spray drying, the antifoaming agent and/or dispersant can be mixed into the polymer beforehand, or simultaneously with the polymer, but each can be introduced separately in dry form into the spray drying tower. It is also possible to produce a powdered dispersant with good dispersibility.

These antifoaming agents and dispersants are used to reduce the amount of air in the mixture and improve fluidity when the powdered dispersant is kneaded with hydraulic cement and/or water. Improves density and density.

Antifoaming agents include oils and fats such as sesame oil, fatty acids such as stearic acid, alcohols such as octyl alcohol, partial esters of polyhydric alcohols and fatty acids such as sorbitan fatty acid ester, polyoxyethylene polyoxybrobylene, paraffin, and Commercially available silicone-based products include Toshiba Silicone (product name: rTSA732), alcohol-based products (product name: Calalin 302) from Sanyo Chemical Industries, Ltd., and polyoxyethylene polyoxypropylene ether-based products from Toho Co., Ltd. “Pronal 5” manufactured by Kagaku side
02'' and ``Antihome ε-20J'' manufactured by Kao ■.

The amount of antifoaming agent used is preferably about 1 to 5 parts by weight based on 100 parts by weight of solid content of the polymer.

Furthermore, it is effective to use a high performance water reducing agent as a dispersant.

High-performance water reducers are used to ensure wettability and fluidity when mixing various materials with water, and even when added in large amounts, they do not cause excessive air entrainment or delay in hydration of hydraulic cement materials. It is a surfactant that has a large dispersing power without any oxidation. For example, salts of melamine sulfonic acid formaldehyde condensates, salts of alkylnaphthalene sulfonic acid formaldehyde condensates, salts of naphthalene sulfonic acid formaldehyde condensates, high molecular weight trigenine sulfonates, polycarboxylate salts, etc. as main components. can be mentioned. Among these, salts of formaldehyde condensates of naphthalenesulfonic acid and alkylnaphthalenesulfonic acids are effective in terms of economy and dispersion effect.

When kneading a powdery dispersant with good dispersibility with hydraulic cement, the amount of the high performance water reducing agent used is preferably 3 parts by weight or less per 100 parts by weight of the hydraulic substance.

As described above, a powdery dispersant with good dispersibility can be obtained without causing wall deposits during the spray drying process. The obtained powdered dispersant with good dispersibility has extremely good storage stability.
Long-term storage is possible even at relatively high temperatures of around 50°C.

When the powdered dispersant of the present invention is stirred and mixed with water, a dispersion having good storage stability can be obtained again within a few seconds.

The particle size of the polymer in this dispersion is approximately the same as the particle size of the polymer obtained by initial polymerization.

The powdered dispersant with good dispersibility obtained by the above operation is used as an admixture for hydraulic cement to obtain dense and durable concrete, as a repair material,
It covers a wide range of products, including flooring materials, waterproofing materials, adhesives, and building materials.

(Example) The present invention will be further explained below with reference to Examples.

Example 1 A pressurized reaction vessel was charged with 35 parts by weight of vinyl acetate, 65 parts by weight of 2-ethylhexyl acrylate, 4 parts by weight of polyoxyethylene nonylphenyl ether as an emulsification stabilizer, and 100 parts by weight of water. After replacing the air with nitrogen, the ethylene introduction pressure was set to 50 kgf/cm',
After saturated dissolution, the reaction vessel temperature was increased to 60°C. The pressure was maintained at 50 kgf/cm', and a potassium persulfate aqueous solution was added to initiate polymerization. After 5 hours, it was cooled and the remaining monomer was 0.48% by weight of ethylene/vinyl acetate/2.
A copolymer dispersion with a solid content of 50% by weight was obtained. The average particle size of the copolymer dispersion was 1μ, and the solid content concentration was 50
% by weight.

Thereafter, 10% by weight of a β-naphthalenesulfonic acid formaldehyde condensate salt and "Cellflow 110 PJ" (trade name, manufactured by Daiichi Kogyo Seiyaku ■) as a dispersant were added to this copolymer dispersion.
Further, 2.5% by weight of polyoxyethylene polyoxypropylene-based "Pronal 502" manufactured by Toho Chemical Co., Ltd. was added and mixed as an antifoaming agent.

The produced synthetic resin emulsion and the anti-caking agent in the amount shown in Table 1 were spray-dried. As for the spray drying equipment, Nippon Dairy Machinery ■Product name: "West German Nubilosa method spray dryer"
was used.

The spray drying apparatus is of a ball fluid nozzle type, and the cylindrical part has a diameter of 1.6 m and a length of 2 m, and the conical part has a length of 2 m.

The above copolymer dispersion was discharged from the center pipe of a 5-diameter ball fluid nozzle at a rate of 300 g/H, and a slurry in which the anti-caking material was diluted to 5% by weight with water was further added from the outer pipe.
Compressed air was discharged from the outer tube at a rate of 3 kgf/cm''. The temperature at the tower inlet was 140-150°C, and in the cyclone separator it was 60-65°C. The obtained powdered dispersant with good dispersibility The average particle diameter was about 10 μ in all cases, and the particles were easily disintegrated even after being stored for one month at 50° C. and under a load of 250 kgf/cm”. The results of these chemical analyzes are shown below.
1 will be listed together.

Also, the bulk density of this powdered dispersant is 38g/d! and
It was easily redispersed in water, and the average particle size of the particles of the synthetic resin emulsion after redispersion was 1 μ. The table below shows the results of manufacturing mortar using these powdered dispersants with good dispersibility.
Also listed in 1.

(Materials used) Cement: Onoda Cement ■Product name "Onoda White Cement", specific gravity 3.14 Anti-caking material α: Tokuyama Soda ■Product name rFinesi
lT32-3J, average particle size 0.
015 μ 〃 β: Product name “Silica Sium” manufactured by Japan Heavy and Chemical Industry ■, average particle size 0.1 μ by transmission electron microscope Fine aggregate: Product name “Silica Sand No. 7” manufactured by Hisago Sangyo ■ Defoaming agent
2.Product name: rTSE 732J, manufactured by Toshiba Silicone ■Dispersant: Product name, "Cellflow 110PJ," manufactured by Dai-Kogyo Seiyaku
Salt of main component naphthalene sulfonic acid formalin condensate (Measurement method) Strength: Compressive strength is measured according to JAS R5201, adhesive strength is measured according to JIS R6916.

Crack resistance: center radius 1cm, edge width 5cm,
Mortar was poured into a gourd-shaped iron formwork with an overall length of 20 cm and a thickness of 5 mm, and cracks were observed.

Curing: 20°C, humidity 60% (Effects of the invention) According to the method of the invention, a powdery dispersant with good dispersibility was obtained.

This powdered dispersant can be stored for a long time.

Furthermore, by using the powdered dispersant of the present invention as an admixture for hydraulic cement, it has become possible to obtain concrete that is dense and has excellent durability.

Claims (2)

[Claims] (1) 100 parts by weight of solid content of synthetic resin emulsion and/or synthetic rubber latex and an average particle size of 0.005 to 0.005
A powdery dispersant comprising 31 to 99 parts by weight of an anti-caking agent containing a 50μ hydraulic material and/or a cement hydrate as an essential component. (2) 100 parts by weight of solid content of synthetic resin emulsion and/or synthetic rubber latex and an average particle size of 0.005 to 0.005.
A method for producing a powdery dispersant, which comprises introducing 31 to 99 parts by weight of an anti-caking material containing 50μ of a hydraulic substance and/or a cement-based hydrate into a spray drying tower and spray-drying it. .