JPS64338B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to cement modifiers. Hardened cement mortar, which is obtained by mixing various aggregates such as sand, pebbles, and crushed stone with cement and water and molding it, is nonflammable, has high compressive strength, and has a heavy feel, making it an excellent structural material. It is widely used in the civil engineering and architectural fields because of its properties, including tensile strength, bending strength, compressive strength, impact resistance, abrasion resistance, deformation resistance, waterproofness, chemical resistance, freeze-thaw resistance, etc. is insufficient. In addition, uncured mortar has drawbacks such as low water retention, large shrinkage during drying, easy cracking, poor adhesion to the base, and inability to apply thinly. In order to improve these drawbacks, conventional synthetic rubber latexes such as styrene-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, polyvinyl acetate emulsion, vinyl acetate-ethylene copolymer emulsion, and polyacrylic acid have been used. A method of modifying cement mortar by mixing a synthetic resin emulsion such as an ester emulsion alone into cement mortar is known. In particular, it is well known that synthetic rubber latex is superior to aqueous dispersions of other polymers in terms of water resistance, alkali resistance, impact resistance, and deformation resistance, and is in widespread practical use today.
However, even if synthetic rubber latex is mixed alone into cement mortar, the water retention capacity of uncured cement mortar is not necessarily sufficient, and its adhesion to porous subsurfaces such as old concrete is not sufficient, so its application is significantly limited. It has drawbacks such as limited range. In order to improve this property, water-soluble polymers such as cellulose derivatives such as methyl cellulose and hydroxyethyl cellulose, polyvinyl alcohol, starch derivatives, isobutylene/maleic anhydride copolymers, and polyacrylic acid ester partial hydrolysates are added to cement together with synthetic rubber latex. A common method is to mix it into mortar to improve water retention. However, this method increases the viscosity of the system, resulting in a decrease in workability. In order to improve workability, it is necessary to increase the water/cement ratio, and as a result, the physical properties of the hardened cement mortar deteriorate significantly. On the other hand, synthetic resin emulsions such as polyvinyl acetate, vinyl acetate/ethylene copolymer, and vinyl acetate/(meth)acrylic acid ester copolymer emulsions that have a protective colloid layer have a water-soluble polymer on the surface of the polymer particles. Because it is covered, it has extremely high water retention. However, when these synthetic resin emulsions are mixed alone into cement mortar, there are drawbacks such as poor alkali resistance of the hardened cement mortar and alkali swelling. Particularly when the polymer/cement ratio is relatively high, the fluidity of the mortar becomes extremely poor, which necessitates a high water/cement ratio, which results in a marked decline in the physical properties of the hardened cement mortar and also in its water resistance. It had to get worse. As a result of intensive studies to improve the water retention properties of uncured cement mortar in which synthetic rubber latex is mixed into cement mortar, the inventors of the present invention have found that they use a combination of synthetic rubber latex and synthetic resin emulsion with a protective colloid layer formed thereon. It was discovered that a cement mortar free from the above-mentioned drawbacks could be obtained, and based on this knowledge, the present invention was completed. That is, in the present invention, (A) about 25 to 55% by weight of conjugated diolefin, α, β
- Synthetic rubber latex having a copolymer composition containing about 0.05 to 5% by weight of ethylenically unsaturated carboxylic acid as a carboxyl group, with the balance being other polymerizable vinyl monomers, and (B) a synthetic resin on which a protective colloid layer is formed. It consists of an emulsion, and the solid content weight ratio of (A)/(B) is approximately
It relates to a cement modifier having a ratio of 40/60 to 95/5. The synthetic rubber latex (A) used in the present invention includes about 25 to 55% by weight of conjugated diolefin,
It has a copolymer composition containing approximately 0.05 to 5% by weight of α,β-ethylenically unsaturated carboxylic acid as a carboxyl group, and the remainder being other polymerizable vinyl monomers. When the amount of conjugated diolefin exceeds 55% by weight, the fluidity of the unhardened cement mortar decreases, and the mechanical strength of the hardened cement mortar also decreases significantly. If it is less than 25% by weight, the fusion of the polymer particles in the mixed synthetic rubber latex will be incomplete, and the impact resistance of the hardened cement mortar will be greatly reduced, and in either case, the performance of the cement will not be fully exhibited. If the α,β-ethylenically unsaturated carboxylic acid is less than 0.05% by weight as a carboxyl group, the synthetic rubber latex will not have sufficient stability during polymerization.
Furthermore, the stability of mixing with the synthetic resin emulsion described later is poor, and as a result, the effect of mixing cannot be sufficiently exhibited. In addition, if the above carboxylic acid exceeds 5% by weight as a carboxyl group, the alkali swelling property of the synthetic rubber latex becomes significant, resulting in poor fluidity of the mixed cement mortar, an increase in the water/cement ratio, and dryness. The contraction becomes large. Examples of the conjugated diolefin include butadiene, isoprene, 2,3-dimethylbutadiene, and butadiene is particularly preferred. Examples of the α,β-ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, and citraconic acid. Acrylic acid and itaconic acid, which have high water solubility, are particularly preferred from the viewpoint of stabilizing the copolymer and particles. Examples of other polymerizable vinyl monomers include (meth)acrylic esters such as styrene, vinyltoluene, α-methylstyrene, acrylonitrile, ethyl acrylate, and methyl methacrylate. The synthetic rubber latex (A) is produced by a method known per se using conjugated diolefin, α,β-ethylenically unsaturated carboxylic acid and other polymeric vinyl monomers in the presence of a surfactant and a radical polymerization initiator. manufactured by The surfactant may be an anionic emulsifier alone, but an anionic emulsifier and a nonionic emulsifier may be used in combination. Examples of anionic surfactants include polyacrylates, anionic polymer surfactants such as isobutylene/maleic anhydride copolymers, alkylaryl sulfonates, alkyl sulfate salts, alkylaryl polyoxyethylene sulfate salts, Alkyl diphenyl ether sulfonates, alkylaryl polyoxyethylene sulfonates, etc. are suitable, and the amount used is about 0.05 to 5% by weight, preferably about 0.5% by weight based on the monomer.
~2.0% by weight. Nonionic emulsifier
Examples include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, and polyethylene glycol/polypropylene glycol block copolymer with HLB of 10 to 18. The amount used is about 1 to 10% by weight, preferably about 2 to 5% by weight based on the monomer. Examples of the radical polymerization initiator include water-soluble or oil-soluble radical polymerization initiators such as potassium persulfate, ammonium persulfate, hydrogen peroxide, organic peroxide, and azo compounds.
The amount is usually about 0.1 to 10% based on the polymer solids content.
It is about % by weight. The synthetic rubber latex used in the present invention is preferably stabilized by adding a nonionic emulsifier after completion of polymerization. Nonionic emulsifiers suitable for subsequent addition include, in addition to the above-mentioned nonionic emulsifiers with HLB10 to HLB18, examples include polyoxyethylene polybenzyl phenyl ether, polyoxyethylene styryl phenyl ether, polyoxyethylene alkylamine, polyoxyethylene Examples include alkyl polyamines. The amount thereof is about 1 to 10% by weight, preferably about 2 to 5% by weight based on the solid content of the latex. Examples of the synthetic resin emulsion forming the protective colloid layer (B) used in the present invention include emulsions of polyvinyl acetate, vinyl acetate/ethylene copolymer, and vinyl acetate/(meth)acrylic acid ester copolymer. can give. This synthetic resin emulsion can be produced by a known emulsion polymerization method using a water-soluble polymer as an aid for forming a protective colloid. In addition to the protective colloid forming aid, a known nonionic emulsifier or anionic emulsifier may be used as a surfactant.
A system in which a protective colloid forming aid is used alone or a protective colloid forming aid is used in combination with a nonionic emulsifier is preferred. As a protective colloid forming aid,
For example, polyvinyl alcohol, starch, or cellulose derivatives are used, and polyvinyl alcohol and hydroxyethyl cellulose are particularly preferred, and the amount used is about 1 to 100% of the solid content of the polymer.
It is about 10% by weight. As the nonionic emulsifier, the above-mentioned nonionic emulsifier having an HLB of 10 to 18 is preferable, and the amount thereof is about 1 to 5% by weight based on the solid content of the polymer. Anionic emulsifiers may be used, but those that form insoluble salts with cement components, such as fatty acid salts and resinates, are not preferred. The cement modifier of the present invention combines (A) synthetic rubber latex and (B) synthetic resin emulsion into (A)/(B).
It is obtained by mixing at a solid content weight ratio of about 40/60 to 95/5, preferably about 50/50 to 80/20. Mixing can be done by any method that ensures uniform mixing of the two, and any type of stirrer can be used for this purpose. When using the cement modifier of the present invention, it is sufficient to simply mix the cement modifier into cement.
The proportion thereof is about 5 to 40% by weight, preferably about 10 to 25% by weight as resin solids based on cement. If the amount is less than 5% by weight, the effect of addition is not sufficient. On the other hand, if the amount exceeds 40% by weight, the matrix of the resulting hardened product becomes that of a polymer and is out of the range of cement mortar. The mixing means may be any known means such as hand mixing or a mortar mixer. When mixed, for example, antifoaming agents, water retention agents, fluidity improvers, AE agents, water reducing agents, waterproofing agents, swelling agents, foaming agents, preservatives, fungicides, rust preventives, coloring agents such as pigments, anti-freezing agents, etc. There is no problem even if known fillers such as additives, plasticizers, membrane-forming aids, and artificial lightweight aggregates are used in combination. Any type of cement may be used, but concrete examples include Portland cement,
Examples include alumina cement and blast furnace cement. Cement mortar mixed with the cement modifier of the present invention has excellent fluidity, compressive strength, impact resistance, adhesion, etc., so it can be used for example in ordinary concrete, lightweight concrete, mortar, gypsum board, PC board, ALC board, etc. , finishing and repair of various substrates such as slate boards, plywood boards, various lath boards, steel boards, waterproof mortar, waterproof concrete, concrete frames, roads, sidewalks, floors, etc.
It is advantageously used in concrete for bridges, etc. Next, the present invention will be explained in more detail with reference to Examples. Example 1 A reactor was charged with 5% by weight of the following composition, 10 g of potassium persulfate, and 2000 g of deionized water, and replaced with nitrogen. Next, 5% by weight of the following composition was added, and the reaction temperature was set at 60°C. Composition polyoxyethylene nonyl phenyl ether (Emulgen 911; Kao Stone) 80g Sodium dodecylbenzenesulfonate 20g Deionized water 260g Composition styrene 1100g Butadiene 850g Acrylic acid
50g (1.6 as carboxyl group)
(equivalent to weight %) After confirming the start of polymerization, the remaining part of the composition was continuously fed for 5 hours. After polymerization for 8 hours, the mixture was cooled and 28% ammonia water was added until the pH reached 8. An SBR latex with a solid content concentration of 48% by weight was obtained. Example 2 A reactor was charged with 5% by weight of the following composition, 1 g of formalin-condensed sodium naphthalene sulfonate, 8 g of ammonium persulfate, and 2000 g of deionized water, and the reactor was purged with nitrogen. Next, 5 of the following composition
% by weight and set the reaction temperature to 55°C. Composition Sodium dodecylbenzenesulfonate 10g Acrylic acid
40g (1.25 as carboxyl group)
(equivalent to weight %) Deionized water 250g Composition Styrene 1200g Butadiene 760g After confirming the start of polymerization, the remaining parts of the composition were continuously fed for 6 hours. After polymerization for 9 hours, the mixture was cooled and 28% ammonia water was added until the pH reached 8. An SBR latex with a solid content of 47% by weight was obtained. Polyoxyethylene nonyl phenyl ether (Emulgen) is added to this SBR latex.
920; Kao stone〓) was added in an amount of 2% by weight. Example 3 Charge the following raw materials to the reactor Alkylaryl polyoxysulfate ester salt (Levenol WZ; Kaoseki) 20g Formaldehyde sodium sulfoxylate (Rongalitz) 0.8g Ferrous sulfate 0.001g Itaconic acid
20g (0.67 as carboxyl group)
2000 g of deionized water, 600 g of styrene after nitrogen substitution, and 390 g of butadiene are charged, and the reaction temperature is set at 40°C. Add 0.8 g of cumene hydroperoxide and carry out polymerization for 6 hours. Furthermore, the following raw materials were added and polymerization was carried out for 8 hours. Alkylaryl polyoxyethylene sulfate salt (Levenol WZ) 20g Sodium formaldehyde sulfoxylate (Rongalitz) 0.8g Ferrous sulfate 0.001g Deionized water 200g Styrene 600g Butadiene 390g After cooling, add 28% ammonia water until pH8. do. An SBR latex with a solid content concentration of 48% by weight was obtained. To this SBR latex, 2% by weight of polyethylene glycol propylene glycol block copolymer (Pluronic F-68; Asahi Denka) was added. Reference example 1 Charge the following raw materials into the reactor.Levenol WZ 60g Polyoxyethylene nonyl phenyl ether (Emulgen 950) 60g Sodium acetate trihydrate 6g Acetic acid 0.6cc Deionized water 2000g Vinyl acetate monomer 200g Nitrogen substitution and ethylene substitution After this, the contents are heated to 70°C. Ammonium persulfate (10
% by weight) to start polymerization by adding 40 g of aqueous solution.
Maintain the ethylene pressure at 40Kg/cm ² during polymerization. 1800 g of vinyl acetate monomer was continuously fed over 3 hours, and the polymerization was completed in 7 hours. A vinyl acetate/ethylene copolymer emulsion with a solid content concentration of 54% by weight was obtained. Comparative Example 1 Polymerization was carried out using the same recipe as in Example 1, but with the amount of acrylic acid increased to 250 g (corresponding to 7.1% by weight of carboxyl groups). Comparative Example 2 Polymerization was carried out using the same recipe as in Example 1, with the amount of acrylic acid reduced to 0.4 g (corresponding to 0.01% by weight as carboxyl groups). Comparative Example 3 Polymerization was carried out using the same recipe as in Example 2, using 1560 g of styrene and 400 g of butadiene. Comparative Example 4 Polymerization was carried out using the same recipe as in Example 2, using 760 g of styrene and 1200 g of butadiene. Table 1 shows the physical properties of a polymer cement mortar prepared by mixing a mixture of synthetic rubber latex and synthetic resin emulsion with a solid content ratio of 60:40 at 10% by weight based on Portland cement.

[Table] Mixtures of the synthetic rubber latex of Example 2 and Sumikaflex 400, which were stabilized by adding 2% by weight of Emulgen 920 based on the solid content after polymerization, were mixed in various ratios to Portland cement to 10% by weight.
The physical properties of the cement mortar mixed in the amount by weight were as shown in Table 2.

【table】

【table】

Claims (1)

[Claims] 1. (A) about 25 to 55% by weight of a conjugated diolefin;
(B) A protective colloid layer is formed with a synthetic rubber latex having a copolymer composition containing approximately 0.05 to 5% by weight of α,β-ethylenically unsaturated carboxylic acid as a carboxyl group, and the remainder being other polymerizable vinyl monomers. It consists of a synthetic resin emulsion with a solid content weight ratio of (A)/(B) of approximately
A cement modifier with a ratio of 40/60 to 95/5.