JPH027899B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel admixture for hydraulic substances, particularly cement and mortar, which has a synthetic resin emulsion as its main ingredient. When preparing synthetic resin emulsions used as admixtures for hydraulic materials such as cement and mortar, the method differs slightly depending on the type of resin, but in all cases the use of emulsifiers or protective colloids is essential. be. For example, vinyl acetate,
To prepare emulsions of vinyl polymers such as acrylic esters and vinyl chloride, the monomers are emulsion polymerized in the presence of an emulsifier or protective colloid, and polyester resin emulsions, epoxy resin emulsions, To prepare a silicone resin emulsion, etc., the above resin in solution or molten form is dropped into an aqueous solution containing an emulsifier or protective colloid and stirred to form an emulsion, or an aqueous solution of an emulsifier or a protective colloid is added to the molten resin. Emulsion formation is carried out by dropping and stirring. As typical emulsifiers or protective colloids, nonionic surfactants and anionic surfactants are used alone or in combination,
Polyvinyl alcohol (PVA) is used, but there are many problems with the mechanical stability of the emulsion obtained when using a surfactant system.
The use of PVA-based materials has become mainstream. However
When using a partially saponified PVA with an average degree of saponification of about 88 mol%, an emulsion with high structural viscosity, low temperature dependence of viscosity, and good freeze stability or storage stability at low temperatures is produced. However, the water resistance is insufficient, and the average degree of saponification is 99.
When using a completely saponified emulsion of about mol%, an emulsion with high water resistance and a small structural viscosity index can be obtained, but the viscosity is highly dependent on temperature and the freezing stability and storage stability at low temperatures may be poor. Each type of emulsion is well-known and is used depending on the purpose of the emulsion. However, with the advancement of technology, emulsions with the above-mentioned properties alone are no longer satisfactory, and the performance of both emulsions using partially saponified PVA and completely saponified PVA has been improved. There is a need for an emulsion that has a suitable structural viscosity index, excellent water resistance, low temperature dependence of viscosity, and good freeze stability and storage stability at low temperatures. In order to obtain an emulsion with such performance, it is possible to use a mixture of partially saponified PVA and completely saponified PVA, but in this case, each
In many cases, the characteristics of PVA cancel each other out, and the drawbacks of each PVA become more apparent. However, the present inventors have conducted various studies on emulsifiers or protective colloids that can simultaneously satisfy these various properties of emulsions, and have found that by using acetoacetylated PVA as an emulsifier or protective colloid, emulsions with excellent properties can be obtained. was obtained and found to be extremely useful as an admixture for hydraulic substances, leading to the completion of the present invention. According to the present invention, the following remarkable effects can be obtained. 1) The emulsion's low-temperature storage stability and freeze-thaw stability are improved. 2) Emulsions with high viscosity can be obtained even at low concentrations. 3) Water resistance can be more easily strengthened by using in combination with a crosslinking agent (aldehydes, amines, metal salts, etc.). 4) It can be used in the same way as when PVA is used as an emulsifier, and can be used in a wide range of ways, including in combination with surfactants. 5) Since it has excellent cohesiveness with clay minerals, it has particularly good adhesion with cement and exhibits strong water resistance. 6) Wastewater containing the emulsion can be easily treated by coagulation and precipitation using clay or the like. The acetoacetylated PVA used in the present invention is
Obtained by reacting PVA and diketene. (The chemical reaction formula is

It is shown by [Formula]. ) For example, PVA is dispersed in an acetic acid solvent,
One method is to add diketene to this, and the other is to dissolve PVA in a solvent such as dimethylformamide or dioxane in advance and add diketene to it. It is also possible to obtain acetoacetylated PVA by directly contacting PVA with diketene gas or liquid diketene. use here
PVA can be used not only in saponified polyvinyl acetate, but also in PVA that has been slightly modified with carboxyl groups, amide groups, nitro groups, carboxylic acid ester groups, hydrocarbon residues, sulfonic acid (salt) groups, etc. It is. The average degree of saponification and average degree of polymerization of acetoacetylated PVA are not particularly limited, but from the viewpoint of effectiveness as a protective colloid, residual acetate groups should be 0.1 to 15 mol%,
The average degree of polymerization is preferably in the range of 500 to 2,600. The content of acetoacetyl groups is suitably in the range of 0.05 to 25 mol%, preferably 1 to 15 mol%. 0.05 mol%
If the amount is less than 15 mol %, the contribution to the water resistance, stability, and thickening property of the emulsion is undesirable. In order to prepare the acetoacetylated PVA-containing synthetic resin emulsion of the present invention, monomers are emulsion polymerized using acetoacetylated PVA as an emulsifier or protective colloid, and a solution or melt of the synthetic resin is mixed in the presence of acetoacetylated PVA. The above three cases include the production of a more stable emulsion by adding acetoacetylated PVA to a synthetic resin emulsion obtained by any method that is post-emulsified. Each case will be specifically explained below. Emulsion Polymerization Method This method is usually suitably carried out when producing a polymer emulsion of a vinyl compound.
During emulsion polymerization, water, acetoacetylation
A conventional emulsion polymerization method can be carried out, in which a vinyl compound is added once or continuously in the presence of PVA and a polymerization catalyst, followed by heating and stirring. The appropriate amount of acetoacetylated PVA to be used is about 0.1 to 30% by weight, preferably about 2 to 20% by weight, based on the solid content of the polymer. If it is less than 2% by weight, sufficient effect cannot be obtained, and 20
If the amount exceeds % by weight, the effect will not increase in proportion to the amount used. The acetoacetylated PVA can be added at any time, such as at the beginning, during or after emulsion polymerization, but it is usually added at the beginning or during the emulsion polymerization. Vinyl compounds used in this method include vinyl acetate, vinyl propionate, acrylic ester, methacrylic ester, vinyl chloride, vinylidene chloride, acrylonitrile,
methacrylonitrile, styrene, ethylene,
Glycidyl group-containing compounds such as propylene, glycidyl acrylate, glycidyl methacrylate, glycidyl divinyl ether, glycidyl vinyl ether, methylol group-containing compounds such as N-methylolacrylamide and N-methylolmethacrylamide, and alkoxy group-containing derivatives thereof, acrylamide, methacrylamide, etc. Carboxylic acid amides, carboxylic acids such as acrylic acid and methacrylic acid, divinyl adipate,
Divinyl succinate, triallyl cyanurate, diallyl fumarate, triallyl citrate, diallyl maleate, vinyl versatate,
These include homopolymerization or copolymerization. Among these, ethylene and vinyl acetate alone or a copolymer thereof are preferred. N
- By using a vinyl compound containing a methylol group or a glycidyl group, a self-crosslinking emulsion can be produced, and an admixture with good water resistance can be prepared. As the emulsion polymerization catalyst, a catalyst used in normal emulsion polymerization is used. Redox catalysts are particularly preferred, and specific examples include hydrogen peroxide and formaldehyde/zinc sulfoxylate, glyoxal/zinc sulfoxylate, glyoxylic acid/zinc sulfoxylate, hydrogen peroxide, ammonium persulfate, or potassium persulfate and methane. sodium bisulfite, sodium bisulfite,
Examples include combinations with ferrous sulfate, dimethylaniline, formaldehyde zinc sulfoxylate or formaldehyde sodium sulfoxylate. Furthermore, nonionic surfactants and ionic surfactants can also be used in combination with acetoacetylated PVA. Furthermore, other emulsifiers such as PVA, cellulose derivatives (carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, etc.), polyacrylic acid derivatives, ((anhydrous) maleic acid-vinyl ether copolymer, ((anhydrous) maleic acid)
Vinyl acetate copolymer, saponified vinyl acetate-(meth)allylsulfonic acid (salt) copolymer, etc. can also be used in combination as appropriate. Other various additives, regulators, etc. used in ordinary emulsion polymerization can also be used as appropriate. Method by post-emulsification This method is suitably carried out when preparing a synthetic resin emulsion that is difficult to produce by emulsion polymerization. In this method, acetoacetylated PVA may be dissolved in water, and a solution or molten resin may be added dropwise to the solution and stirred, or an aqueous solution of acetoacetylated PVA may be dropped into the molten resin and stirred. There is no particular need for heating to form an emulsion, but if necessary, it may be heated to about 45 to 85°C. The substances to be emulsified are not particularly limited, and include epoxy resins, urethane resins, urea-formalin initial condensates, phenol-formaldehyde initial condensates, alkyd resins, polyester resins,
Examples include ketene dimer, silicone resin, wax, polypropylene, polyethylene, and the like. The amount of acetoacetylated PVA to be used varies somewhat depending on the resin content of the required emulsion, etc., but it is usually selected from the range of 0.1 to 30% by weight, preferably 1 to 25% by weight based on the material to be emulsified. . If necessary, a nonionic activator such as a polyoxyethylene-alkyl ether type, a polyoxyethylene-alkyl phenol type, a polyhydric alcohol ester type, or a cationic activator such as a higher alkyl amine salt is used in combination with the resin, if necessary. You can also. It is also possible to mix these active agents into the object to be emulsified. Post-addition method This method is carried out by adding acetoacetylated PVA to a synthetic resin emulsion obtained by any method for the purpose of further improving stability or thickening. Targeted emulsions include styrene/butadiene emulsions, cis-1,4 polyisoprene emulsions, chloroprene emulsions, acrylonitrile/butadiene emulsions, vinylpyridine emulsions, methyl methacrylate/butadiene emulsions, polyurethane emulsions, and acrylic esters. emulsions, vinyl acetate emulsions, ethylene/vinyl acetate emulsions, vinyl chloride emulsions, polystyrene emulsions, polyethylene emulsions, silicone emulsions, polybutene emulsions, thiol emulsions, and the like. When adding and mixing acetoacetylated PVA to an emulsion, when adding the PVA as an aqueous solution, it is sufficient to simply add the aqueous solution to the emulsion at room temperature while stirring, but when adding the PVA powder, , add the powder while stirring the emulsion, stirring for 60 to 80 minutes.
It is preferable to heat the mixture to ℃ because uniform mixing can be completed in a short time. The amount of acetoacetylated PVA used ranges approximately from 0.1 to 30% by weight, preferably from 0.1 to 10% by weight, based on the emulsion. Acetoacetylation with a small degree of acetoacetylation
When using PVA, increase the amount added and avoid acetoacetylation with a high degree of acetoacetylation.
When using PVA, a small amount will produce effects such as thickening. That is, the viscosity increasing effect and the stability improving effect are approximately proportional to the degree of acetoacetylation and the amount added. Therefore, it is desirable to understand these relationships and then select the degree of acetoacetylation and the amount added depending on the purpose. Thus, the emulsion obtained can be used as it is or, if necessary, can be further treated with plasticizers, membrane-forming agents such as high-boiling solvents, clay, calcium carbonate,
Extender pigments such as kaolin and diatomaceous earth, colored pigments such as titanium oxide, preservatives, insect repellents, rust preventives, thickeners, etc. are appropriately blended and used. In particular, metal compounds,
(Beryllium, zirconium, titanium, chromium, calcium, magnesium, zinc, barium, strontium, aluminum, bismuth,
Oxides, hydroxides, basic salts, acidic salts, neutral salts, amine complexes, etc. of antimony, cobalt, iron, nickel, etc.) Formaldehyde, glyoxal, dimethylolated products of urea or melamine, isocyanate compounds, epichlorohydrin, ethylene glycol The combined use of curing agents such as various epoxy compounds such as diglycidyl ether, glycerol di- or triglycidyl ether has the effect of further improving the water-resistant adhesive strength. Preferred metal compounds include zinc acetate, zinc oxide, zinc glycinate, chromium nitrate, titanyl sulfate, zinc carbonate, aluminum chloride, zinc benzoate, zinc salicylate, zinc glycolate, calcium hydroxide, magnesium oxide, titanium lactate, and the like. It will be done. It is also possible to add a water-soluble polymer substance for the purpose of increasing viscosity. The amount added is usually in the range of 5 to 500% in terms of solid content based on the emulsion. Such water-soluble polymer substances include
Examples include PVA, starch, CMC, hydroxymethylcellulose, hydroxyethylcellulose, methylcellulose, casein, etc., and these can be mixed in any form such as an aqueous solution or powder. The hydraulic material in the present invention may be any material such as cement or gypsum, but cement is particularly preferred. Cement products such as concrete structures, blocks, piles, mortar, and slate, which are obtained by mixing and molding various aggregates such as cement, sand, pebbles, and crushed stone, and water are widely used in the fields of civil engineering and architecture. However, it has drawbacks such as low resistance to tension, bending, and impact, easy cracking, and insufficient waterproofness and chemical resistance. The emulsion of the present invention can be used as an admixture for cement in order to improve these drawbacks. In other words, the admixture of the present invention has a
By mixing up to 40% of cement, it is possible to obtain cement products with outstanding mechanical strength such as bending strength, tensile strength, and compressive strength. It is possible to obtain a cement product with excellent properties such as wear resistance, adhesion to old concrete surfaces, and weather resistance. Furthermore, since the admixture of the present invention is stable even in an alkaline atmosphere, it can be mixed as is when molding concrete or concrete analogues by mixing ordinary cement, water, and aggregates such as sand, crushed stone, and pebbles. Can be done. The mixing ratio of these emulsions needs to be in the range of 2 to 40% as a resin solid content to the cement.
If the amount is less than 40%, the above-mentioned remarkable effect cannot be exhibited, whereas if the amount is more than 40%, the mechanical strength will decrease and the cost will increase, which is not appropriate. If necessary, various surfactants can be used in combination. It is usually advantageous to add the activator to the emulsion. Next, the present invention will be specifically explained with reference to Examples. In the examples, "parts" or "%" represent "parts by weight" or "% by weight." Example 1 Acetoacetylated PVA with an average degree of polymerization of 1700, residual acetic acid group 1 mol%, and degree of acetoacetylation 2.3 mol%
An emulsion for cement admixture was obtained in the following manner. In a separable flask equipped with a stirrer, reflux condenser, addition funnel, and thermometer, add 131.3 parts of the above water.
11.5 parts of PVA and 10 parts of vinyl acetate monomer were charged, and the temperature inside the flask was raised to 60°C while stirring. While replacing the inside of the flask with nitrogen gas,
Polymerization was initiated by adding 2 ml of 10% H ₂ O ₂ water and 3 ml of 10% tartaric acid. Initial polymerization was carried out for 30 minutes, and the remaining 90 parts of vinyl acetate monomer was added dropwise over 3 hours.
All the monomers were charged, and the mixture was aged at 70°C for 1 hour and then cooled. The obtained emulsion had good fluidity. Table 1 shows various characteristics. Control example 1 Acetoacetylation used in Example 1
Instead of PVA, use regular PVA (average degree of polymerization 1700,
An emulsion was obtained in the same manner as in Example 1 using 1 mol % of residual acetic acid groups. Table 1 shows various properties of the emulsion. Example 2 Acetoacetylated PVA with average degree of polymerization of 1800, residual acetic acid groups of 12 mol%, and degree of acetoacetylation of 1.6 mol%
An emulsion was obtained in the following manner. In the same apparatus as in Example 1, 155.5 parts of water and the
Initial polymerization was carried out in the same manner as in Example except that 7.0 parts of PVA and 10 parts of vinyl acetate monomer were used. Thereafter, the remaining 90 parts of vinyl acetate monomer was added dropwise over 2 hours, and after completion of the addition, the mixture was aged at 75°C for 1 hour and then cooled. Table 1 shows various characteristics. Control example 2 Acetoacetylation used in Example 2
Instead of PVA, use regular PVA (average degree of polymerization 1800,
An emulsion was obtained in the same manner as in Example 2 using 12 mol % of residual acetic acid groups. Table 1 shows various properties of the emulsion. Example 3 Acetoacetylated PVA with an average degree of polymerization of 1400, residual acetic acid group 1 mol%, and degree of acetoacetylation 5.9 mol%
An emulsion was obtained in the following manner. 11.0 parts of the above PVA, 0.5 parts of Emulgen 950 (polyoxyethylene nonylphenol ether, manufactured by Kao Seiken), 70 parts of vinyl acetate monomer, 30 parts of butyl acrylate, and 101.5 parts of water were charged into the same apparatus as above, and 5 parts of ammonium persulfate was charged. % aqueous solution 5ml,
5 ml of a 5% aqueous solution of sodium bisulfite was added, and emulsion polymerization was carried out at 40 to 50°C for 30 minutes and at 80 to 85°C for 3 hours under a nitrogen gas atmosphere. Table 1 shows various characteristics. Control example 3 Acetoacetylation used in Example 3
In place of PVA, average degree of polymerization 1400, residual acetate group 1
An emulsion was obtained in the same manner as in the example except that mol % of PVA was used. Table 1 shows various characteristics. Example 4 Acetoacetylated PVA with an average degree of polymerization of 1800, residual acetate group 1 mol%, and degree of acetoacetylation 3.5 mol%
An ethylene/vinyl acetate/vinyl chloride copolymer emulsion was obtained in the following manner. Add 100 parts of water and the above to the autoclave for polymerization.
Charge 8 parts of PVA, raise the internal temperature to 65℃ and PVA
Then, ethylene was introduced under pressure to maintain the temperature at 30Kg/ ^cm2 , the internal temperature was raised to 75℃, and 40 parts of vinyl chloride and
Emulsion polymerization was carried out by dropping 45 parts of vinyl acetate and 8 parts of a 5% aqueous solution of ammonium persulfate over 5 hours, the ethylene pressure was returned to normal pressure, and after further aging for 1 hour, the concentration was adjusted to 50%. . Table 1 shows various characteristics. Example 5 Using the same acetoacetylated PVA as in Example 4, a vinyl acetate/veova (vinyl ester of carboxylic acid branched at the α-position: a trade name of Ciel Chemical) copolymer emulsion was obtained in the following manner. Charge 100 parts of water and 8 parts of the above PVA into a polymerization container, raise the internal temperature to 65°C to dissolve the PVA, further raise the temperature to 75°C, and then add 50 parts of Veova and vinyl acetate.
50 parts of ammonium persulfate and 8 parts of a 5% aqueous solution of ammonium persulfate were simultaneously added dropwise over 3.5 hours to carry out emulsion polymerization, and after further aging for 1 hour, the concentration was adjusted to 50%. Table 1 shows various characteristics. Example 6 Using the same acetoacetylated PVA as in Example 4, a butyl acrylate/styrene copolymer emulsion was obtained in the following manner. An emulsion having a concentration of 50% was obtained in the same manner as in Example 5, except that the monomers were changed to 60 parts of butyl acrylate and 40 parts of styrene, and 0.2 parts of dodecyl mercaptan was added as a chain transfer agent.
Table 1 shows various characteristics.

【table】

[Table] Example 7 100 parts of ethylene-vinyl acetate copolymer emulsion (resin content 50%, viscosity 530 cps), polymerization degree 1700,
2.5 parts of acetoacetylated PVA with residual acetate groups of 1 mol % and degree of acetoacetylation of 5.4 mol % were added and mixed. The characteristic values of this emulsion are shown in Table 2. Examples 8 to 13 In Example 8, 100 parts of vinyl acetate resin emulsion (resin content 50%, viscosity 7400 cps) was mixed with acetoacetylated PVA with a degree of polymerization of 1700, residual acetic acid groups 1 mol %, and acetoacetylation degree 2.3 mol %. In Example 9, 2 parts and in Example 10, 6 parts were added and mixed. In addition, 100 parts of the above emulsion has a polymerization degree of 1800 and residual acetic acid groups.
1 part of acetoacetylated PVA with a degree of acetoacetylation of 12 mol% and acetoacetylation degree of 1.6 mol% in Example 11;
In Example 12, 2 parts and in Example 13, 6 parts were added and mixed. The properties of the obtained emulsion are shown in Table 2. Comparative Examples 4 to 6 Comparative Example 4 was the same as Example 7 except that PVA (degree of polymerization 1700, residual acetic acid group 1 mol%) was used, and PVA (degree of polymerization 1700, residual acetic acid group 1 mol%) was used in Example 9. In Comparative Example 5 and Example 12, PVA (polymerization degree
Comparative Example 6 was a case in which the same procedure was carried out except that 1800 and 12 mol % of residual acetic acid groups were used, and the emulsion properties of each are shown in Table 2.

[Table] Example 14 Acetoacetylated PVA with a degree of polymerization of 500, a residual acetic acid group of 1.3 mol%, and a degree of acetoacetylation of 2.3 mol% was produced. Dissolve 4.0g of the above PVA in 31.0g of 50℃ warm water,
Next, 65 g of Epicote 828 (liquid bisphenol A type epoxy resin, manufactured by Shell Chemical Co., Ltd.), which had been preheated to about 50° C., was gradually added and vigorously stirred with a high-speed mixer to obtain an epoxy resin emulsion. The properties of the emulsion are shown in Table 3. Control Example 7 The same experiment as in Example 14 was carried out, except that PVA with a residual acetate group of 1.3 mol % and a degree of polymerization of 500 was used instead of the above PVA. The results are also shown in Table 3. Example 15 8 parts of acetoacetylated PVA having a degree of polymerization of 1700, a residual acetic acid group of 1.9 mol %, and a degree of acetoacetylation of 3 mol % was dissolved in 82 parts of water and kept at 65°C. Next, pre-molten hexadecyl ketene dimer was gradually added dropwise, and emulsion was formed using a homogenizer to obtain a ketene dimer emulsion. The performance of the emulsion is shown in Table 3. Control Example 8 The same experiment as in the above example was carried out except that PVA having a residual acetate group of 1.9 mol % and a degree of polymerization of 1700 was used in place of the above PVA. The results are also shown in Table 3. Example 16 15 parts of the emulsifier used in Example 15, 15 parts of water, 100 parts of atactic polypropylene (average molecular weight 18,000)
A small amount of octadecylamine acetate was kneaded in a pressure kneader at a temperature of 9° C. for 20 minutes. Water was added to obtain a polypropylene emulsion with a solids content of 30%. The results are shown in Table 3.

【table】

[Table] Performance evaluation test as a cement admixture 1 A. Preparation of ethylene-vinyl acetate copolymer resin emulsion 50 parts of vinyl acetate (parts by weight, same below), 150 parts of water
3 parts, degree of acetoacetylation 3 mol%, residual acetic acid group 1 mol%, degree of polymerization 1400, 3 parts of acetoacetylated PVA were charged into a pressure polymerization reactor, vinyl acetate was emulsified, and 50 parts of ethylene was added using potassium persulfate as a polymerization catalyst.
The mixture was pressurized to atmospheric pressure and a polymerization reaction was carried out at a temperature of 60°C for 10 hours to obtain a copolymer resin emulsion with an ethylene:vinyl acetate copolymerization ratio of 80:20. B. Preparation of cement mortar As shown in the table, the ratio of resin in the emulsion to cement (emulsion cement ratio) is 20% according to JIS-A6101 (1953) Test method for cement waterproofing agent for construction. It was mixed into a mixture of ordinary Portland cement and Toyoura standard sand and kneaded. Various strengths, water absorption, adhesion, impact resistance, abrasion resistance, and durability of the obtained mortar were measured. As a control example, the same experiment was conducted using ordinary cement mortar to which no ethylene-vinyl acetate copolymer resin emulsion was added.

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Claims (1)

[Claims] 1. An admixture for hydraulic substances consisting of a synthetic resin emulsion containing acetoacetylated polyvinyl alcohol as a protective colloid.