JPH04243944A - Freezing and thawing stabilizer for polymer emulsion latex - Google Patents

Abstract

PURPOSE:To enable the reconstitution of a polymer emulsion latex to original liquid state after freezing and remelting by adding a compound expressed by specific formula I or formula II to the latex. CONSTITUTION:A polymer emulsion latex having a core-shell type layered structure and an average particle diameter of <2,000nm is produced by the emulsion polymerization of an unsaturated monomer having carboxyl group and ethylenic unsaturated double bond in the presence of an emulsifier. The latex is incorporated with 1.0-2.5wt.% of a freezing and thawing stabilizer expressed by formula I or formula II (R1, R2, R4 and R5 are H, lower alkyl or hydroxyalkyl; R3 is H or hydroxyalkyl; A is ethylene or propylene; m is 1-3; n is 0-3; x is 1-3). The effect can be improved by adding urea, Na2CO3, etc., to the latex. The pot life of cement and/or mortar can be prolonged by compounding 0.3-12wt.% (in terms of solid) of the latex containing the stabilizer to the cement, etc.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to polymer emulsion latex, such as micropolymer emulsion,
The present invention relates to a freeze-thaw stabilizer for crosslinked micropolymer emulsions, and more particularly to a freeze-thaw stabilizer that can extend the usable life of polymer cement mortar and/or concrete by incorporating it into polymer cement mortar and/or concrete.

0002

[Prior Art] Conventionally, polymer emulsion latex was used as an additive to improve the durability of cement mortan and/or concrete, such as preventing cracking, water resistance, abrasion resistance, chemical resistance, and prevention of carbonation. A method of using it as a method is known.

[0003] However, when cement mortar and concrete containing such polymer emulsion/latex are exposed to low temperatures of around -10°C or lower, the blended polymer latex/emulsion freezes, and it is difficult to thaw it. However, the problem is that the cement mortar and concrete no longer return to their original liquid state, making them unusable.

[0004] Cement mortar and concrete mixed with amine compounds are also disclosed in JP-A-1-24616.
Publication No. 4, JP-A-63-123849, JP-A-6
It is described in Japanese Patent No. 3-123850 and the like and is publicly known. In particular, JP-A-1-246164 describes a combination of amidosulfonate and water-soluble aminoethanol, which has improved hardening acceleration and corrosion prevention of cement mortar and concrete. . Furthermore, sodium hydroxide,
Ammonia water etc. are used.

[0005]

Problems to be Solved by the Invention The present invention provides cement mortar containing polymer emulsion latex,
Polymer emulsion latex that overcomes the traditional disadvantages of concrete and can return the polymer emulsion latex to its original liquid state when concrete is exposed to low temperatures and frozen and then thawed again. The present invention provides a freeze-thaw stabilizer.

[0006]

[Means for Solving the Problems] According to the present invention, one or two of the compounds represented by the following general formula 1 or 2
Freeze-thaw stabilizers for polymer emulsion latex are provided that are selected from compounds consisting of or more species.

[Chemical formula 1]

[Formula R1, R2; H, lower alkyl group or hydroxyalkyl group R3; H, or hydroxyalkyl group R4]
, R5; H, lower alkyl group or hydroxyalkyl group A; ethylene or propylene group m
;1~3n;0~3x;1~3)

Generally, when polymer latex and micropolymer emulsion are frozen at -10°C, they no longer return to their original liquid state even when thawed, but by adding the additive of the present invention, they can be frozen at -30°C. Even if it is melted, it can return to its original liquid state. Although the effect is exhibited even when used in a normal emulsion, the effect becomes even more pronounced when used in a micropolymer emulsion. By using the additive of the present invention in cement mortar and concrete containing polymer emulsion latex, the usable life of cement mortar and concrete is extended. By adding one or more compounds represented by the general formula 1 or 2 to the polymer latex and micropolymer emulsion, these additives create a neutralized salt with the functional groups of the polymer, and the By forming a hydration layer, the hydrated salt prevents contact between polymer particles and prevents agglomeration when remelted.

Specific examples of the compound represented by the general formula 1 or 2 of the present invention include the following. Those represented by the general formula 1 include: Ammonia alkanolamines: monoethanolamine, diethanolamine, triethanolamine, etc. Alkyl alkanolamines: N,N-dimethylethanolamine, N,N-diethylethanolamine, N-
Methylethanolamine, N-methyldiethanolamine, etc. Those represented by the general formula 2 include alkyldiamines: N,N-dimethyl 1,3-propanediamine, etc. Alkylalkanoldiamines: N-(β-aminoethyl)ethanolamine, etc.

The amount of the compound represented by formula 1 or 2 of the present invention is 1.0 to 12.5% by weight based on the polymer emulsion latex. If it is less than 1.0% by weight, the freeze-thaw stability will be insufficient, and 12.5% by weight.
If it exceeds % by weight, the fluidity of polymer cent mortar and concrete will decrease.

By using the compound represented by the general formula 1 or 2 of the present invention in combination with urea or the compound represented by the following formula 3, the freeze-thaw stability effect can be further improved.

[Formula 3] MyCO3 (M; alkali metal, alkaline earth metal, or ammonium y; 1 or 2) Compounds represented by the general formula 3 include Na2CO3, CaCO3,
Examples include K2CO3 and (NH4)2CO3. When urea is used alone, the freeze-thaw stability does not improve unless the amount added is increased, and when the compound represented by the general formula 3 is added alone, the freeze-thaw stability is also poor. However, by using the compound represented by the general formula 1 or 2 together with urea or the compound represented by the general formula 3, the freeze-thaw stability becomes good. General formula 1 or formula 2 of the present invention
The total blending amount of the compound represented by and urea or the compound represented by general formula 3 is 1.0 to 12.5% by weight based on the polymer emulsion latex, and the ratio by weight is 9/1. ~1/9. The polymer emulsion latex, which is a compounding component for cement mortar and/or concrete according to the present invention, can be obtained by emulsion polymerization of unsaturated monomers. The unsaturated monomers used in the present invention include acrylic esters with ethylenic double bonds (e.g., ethyl acrylate, butyl acrylate, octyl acrylate, 2-ethylhexyl acrylate), methacrylic esters (e.g., methacrylate), methyl acid, ethyl methacrylate, butyl methacrylate, octyl methacrylate), styrenes such as styrene and α-methylstyrene, dienes such as butadiene and isoprene, vinyls such as vinyl acetate and vinyl propionate,
Examples include nitriles such as acrylonitrile and α-methylacrylonitrile.

Further, in order to improve the dispersibility of cement, it is more preferable to use a copolymerized unsaturated monomer having a carboxyl group and an ethylenic double bond in the molecule. Examples of such unsaturated monomers having a carboxyl group and an ethylenic double bond in the molecule include acrylic acid,
Examples include methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, half esters, half amides, and salts thereof, but it is especially preferable to copolymerize 0.1 to 5% by weight of methacrylic acid. preferable.

Furthermore, in order to improve strength and water resistance, it is preferable to copolymerize a crosslinking agent and/or a reactive unsaturated monomer having a plurality of functional groups in one molecule. Examples of these crosslinking agents and reactive unsaturated monomers include trimethylolpropane triacrylate, glycidyl acrylate, glycidyl methacrylate, bisphenol A polyoxyethylene adduct di(meth)acrylate, triallylisocyanurate, and N-methylol acrylamide. However, it is preferable to copolymerize 0.1 to 5% by weight with respect to the unsaturated monomer.

The polymer emulsion latex most preferably used in the present invention has a core-shell type heterolayered structure, and the weight ratio of the unsaturated monomers constituting the core part and the shell part is 35/65 to 35/65. The weight composition of the unsaturated monomer in the core is 90/10, and the number of carbon atoms in the alkyl group is 1 to 8.
55-100% by weight
Acrylic acid alkyl ester The alkyl group has 1 to 4 carbon atoms.
0-45% by weight
Methacrylic acid alkyl ester crosslinking agent
0～
5% by weight, and the weight composition of the unsaturated monomer in the shell portion is such that the number of carbon atoms in the alkyl group is 1 to 8.
5-49.9% by weight
Acrylic acid alkyl ester
The number of carbon atoms in the alkyl group is 1 to 4
45-90% by weight
Methacrylic acid alkyl ester Ethylenically unsaturated carboxylic acid or its salt
0.1-5% by weight Crosslinking agent

It contains 0 to 5% by weight as an essential component. This is because such polymer emulsion latex can reduce the amount of water used during concrete mixing, and can also improve the durability, weather resistance, and carbonation prevention ability of polymer cement mortar and hardened concrete. This is because it has effects.

As the emulsifier for emulsion polymerization of the polymer emulsion/latex used in the present invention, the following anionic and nonionic emulsifiers are used. [Representative examples of anionic emulsifiers] (1) Polyoxyalkylene alkylaryl ether sulfonate sulfate salt

[Chemical formula 4] (2) Polyoxyalkylene alkyl ether sulfate salt

[Chemical formula 5] R1-O-(AO)n-SO3M1
(In the formula, R1, A, n and M1 are the same as above) (3) Polyoxyethylene alkylaryl ether sulfate salt

[C6] (In the formula, R1, A, n and M1 are the same as above)

[Chemical 7] (4)
OH R2

｜ ｜
CH2-COO-CH2-C
HCH2OCH2C=CH2
| CH-COO-(AO)n-
R3 |
SO3M1 M1, A, n: Same as above R2: Hydrogen atom or methyl group R3: Alkyl group, alkenyl group, or phenyl group having an alkyl group or alkenyl group, fatty acid residue

[chemical 8
] (5) CH2COO-(AO)n-
R3 R
2 ｜

| CH-C
OO-CH2-CH-CH2O-CH2-C=CH2
｜
｜
SO3M1
OH (in the formula, M1, A, n, R2 and R3 are the same as above)

[Chemical formula 9] (6) CH2COOR3
R2
｜
｜
CH-COO(AO)n-CH2-C=CH2
｜
SO3M1
(In the formula, M1, A, n, R2 and R3 are the same as above)

[Chemical formula 10] (7)
R2

｜
CH2-COO-(AO)n-
CH-C=CH2
| CH-COOR3
｜
SO3M1
(In the formula, M1, A, n, R2 and R3 are the same as above)

[Chemical formula 11] (8) CH2COO(AO)nR3
R2
｜

| CH-C
OO(AO)nCH2-CH-CH2O-CH2C=C
H |
| N-R2
OH
| (R4)m | SO3M1
(In the formula, M1, A, n, R2 and R3 are the same m as above: 0,1 R4: -CH2-, -CH2CH2- or phenyl group

[
Chemical formula 12] (9) SO3M1 | (R4)m | N-R2 | CH-COO(AO)nR3

R2 |

｜
CH2COO(AO)nCH2-CH-CH2O-C
H2-C=CH2
｜

OH (M1, A, n, m, R2, R3 and R4 are the same as above) [Representative example of nonionic emulsifier]

embedded image (10) Polyoxyalkylene alkylaryl ether (wherein p is 0 to 100, preferably 5 to 70, R2, A
is the same as above)

[Chemical formula 14] (11) Polyoxyalkylene alkyl ether R1-O-(AO) pH (wherein R1, A and p are the same as above)

These anionic emulsifiers and nonionic emulsifiers can be used alone or in combination, but it is preferable to use one or more emulsifiers having ethylene oxide and propylene oxide groups in the molecule. More preferably, the compound (1) above is used as an anionic emulsifier, and the compound (10) or (11) above is used as a nonionic emulsifier.
It is desirable to use one or more kinds of compounds.

Further, these emulsifiers are preferably used in an amount of 0.5 to 15% by weight, preferably 1 to 10% by weight, based on the unsaturated monomer. As a polymerization initiator, hydrogen peroxide alone or a combination of hydrogen peroxide and a carboxylic acid such as tartaric acid, citric acid, or ascorbic acid, hydrogen peroxide and oxalic acid, sulfinic acid, and their salts or oxyaldehydes, Combinations with water-soluble iron salts, peroxides such as persulfates, percarbonates, perborates, 2,2'-azobis(2-aminodipropane) and its salts, 2,2'-azobis( N,N'-dimethylene-isobutyramidine)
Water-soluble azo initiators such as 4,4'-azobis(4-cyanovaleric acid) and its salts can be used. To prepare the polymer emulsion/latex used in the present invention, the water-soluble azo initiator is added to 0.0% of the unsaturated monomer mixture.
It is preferable to use 1 to 3% by weight.

The polymer emulsion latex used in the present invention can be prepared by the general emulsion polymerization method described below using the unsaturated monomer, emulsifier, and polymerization initiator. That is, after dissolving an emulsifier in an aqueous phase and solubilizing a portion of the core unsaturated monomer, a polymerization initiator is added,
Then, by a monomer dropping method in which the core unsaturated monomer and the shell unsaturated monomer are added dropwise in that order, or by a pre-emulsification method in which an emulsifier, a portion of water, and an unsaturated monomer are pre-mixed and emulsified and then added dropwise. Although it can be prepared by any method of emulsion polymerization, it is more preferable to use the pre-emulsification method in order to reduce the amount of polymer adhered to the polymerization pot or stirring blade, which is a disadvantage of emulsion polymerization. In particular, when producing polymer emulsion latex with a core-shell type different layered structure, it is important to note that the polymerization of the core and the shell form a block-type bond. After completion of polymerization, it is preferable to carry out aging for several minutes to several hours. The polymer emulsion latex used in the present invention has a solid content of 4
The viscosity at 0% by weight is 10 to 1000 cp (Brookfield type viscometer), and the workability is good, and in the case of a low viscosity product, it is possible to have a solid content of 50% or more.

[0019] Furthermore, these polymer emulsion latexes used in the present invention have an average particle diameter of 2000 nm.
less than m, preferably 500 nm or less, more preferably 2
It is desirable to keep the thickness to 00 nm or less. 2000nm
If it is above, the strength, weather resistance, durability, water resistance, and carbonation improvement effect of cement mortar and/or concrete will be insufficient, and the amount used will be larger than that of smaller particle size. So I don't like it.

The amount of polymer emulsion latex mixed into cement and/or concrete is 0.3 to 12% by weight, preferably 0.5 to 10% by weight as a solid content. If it is less than 0.3% by weight, it is not preferable from the viewpoint of durability, water resistance, and prevention of carbonation. Moreover, if it exceeds 12% by weight, the compressive strength, which is a characteristic of hardened cement, decreases, which is not preferable.

[0021] Further, in the present invention, improvement of fluidity,
Furthermore, in order to further improve durability, it is desirable to incorporate a sulfonic acid group-containing polymer at the time of blending and kneading the hydraulic inorganic material and the polymer emulsion latex. In this case, the sulfonic acid group-containing polymer may be blended into the polymer emulsion latex in advance. Examples of such sulfonic acid group-containing polymers include lignin sulfonate, naphthalene sulfonic acid formalin condensate, sulfonated melamine resin, polystyrene sulfonate, and the like. Among these, polystyrene sulfonate is particularly excellent. Counter ions for these salts include alkali metals, alkaline earth metals, amines, alkanolamines, and the like. Particularly preferable counterions are amines and alkanolamines, and these are preferably used in an equivalent ratio or more and a threefold or less ratio to the sulfonic acid. The molecular weight of this polystyrene sulfonate is preferably from 3,000 to 100,000. More preferably, it is 5,000 to 50,000. The blending amount of this polystyrene sulfonate is preferably 0.01% to 4.0% by weight, more preferably 0.1% by weight based on cement.
% to 2.0% by weight. If it is less than 0.01% by weight, it is unfavorable in terms of fluidity and water reduction effect (effect that can reduce the amount of water to be blended), and if it exceeds 4.0% by weight, free water will bleed out and the fluidity will improve. Moreover, it is not preferable because it has poor water resistance and other properties of the cured product.

In the present invention, further, fine particle silica (
Durability can be further improved by using it in combination with frame materials such as silica fume), fly ash, and blast furnace slag, among which silica fume is particularly excellent. Silica fume is effective even when added in powder form, but when it is kneaded in advance with the polymer emulsion latex of the present invention, there is no aggregation of the silica fume, both materials are uniformly dispersed, and the durability of the polymer cement is significantly improved. The particle size of silica fume is a primary particle size of 0.1 μm or less,
The diameter of partially aggregated secondary particles is preferably 1.0 μm to 100 μm, and the purity of SiO2 is preferably 70% or more.

Furthermore, in the present invention, in order to further improve the durability of reinforced cement mortar and/or concrete, it is effective to use a rust inhibitor in combination. Rust inhibitors that can be used in combination include nitrites, chromates, silicates, phosphates, organic phosphates, amines, alkylphenols, mercaptans, and nitro compounds, but the polymer emulsion of the present invention・By using latex together with an organic phosphate rust preventive agent, more preferably a 1-hydroxyalkane-1,1-diphosphonate such as 1-hydroxyethane-1,1-diphosphonate, commercially available anti-corrosion A significant durability improvement effect can be obtained at lower concentrations than nitrates.

In carrying out the present invention, nonionic and anionic polymeric substances, coloring pigments, chelating agents, preservatives, pH adjusters, plasticizers, early strength agents,
A retardant, a conductive (antistatic) agent, a body material (white earth), and a reinforcing agent may be used as auxiliary additive components.

[0025]

[Examples] The present invention will be explained in more detail below with reference to Examples and Comparative Examples. Add a specified amount of various additives to a polymer latex or micropolymer emulsion with the following composition, stir thoroughly, then put it in a 100 ml sample bottle, leave it in a thermostat at -30°C for 16 hours, and then return it to room temperature. The appearance and particle size measurements of latex and micropolymer emulsion were performed. ○…Those whose viscosity did not change after freezing and thawing △…
Items whose viscosity increased after freezing and thawing × Items that did not solidify and become liquid even after being returned to room temperature after freezing Also, when polymer emulsion latex containing these additives was added to cement mortar The mortar properties of were evaluated by the following method. The results are shown in Table 1.
It is shown in Table 2 and Table 3. Evaluation method of mortar properties: Based on JIS R-5201 Cement physical property test method 9.7 flow test (C/5 =
112)

[0026]

[Table 1]

[0027]

[Table 2] Micropolymer emulsion with composition A

002
8]

[Table 3] Micropolymer emulsion of composition A (continued)

[0029]

[Table 4] Micropolymer emulsion with composition B

003
0]

[Table 5] Polymer latex with C composition

As is clear from the Examples and Comparative Examples of the present invention, the freeze-thaw stabilizer of the present invention is extremely superior in the freeze-thaw stability of micropolymer emulsions compared to that of the Comparative Example.

[0032]

Effects of the Invention The present invention provides polymer particles by further blending one or more amine compounds represented by the general formula 1 or 2 into cement mortar and/or concrete containing polymer emulsion/latex. It is possible to strengthen the charge on the surface of
The amine compound acts like a protective colloid, forms a hydration layer, and can return the polymer emulsion/latex to its original liquid state when remelted after freezing.
The effect is that the pot life of concrete can be extended.

Claims (2)

[Claims] 1. A freeze-thaw stabilizer for polymer emulsion latex, which is selected from one or more compounds represented by the following general formula 1 or 2. [Formula 1] [Formula 2] (In the formula, R1, R2; H, lower alkyl group or hydroxyalkyl group R3; H, or hydroxyalkyl group R4
, R5; H, lower alkyl group or hydroxyalkyl group A; ethylene group or propylene group m
;1~3n;0~3x;1~3) 2. The freeze-thaw stabilizer according to claim 1, wherein the stabilizer is used in an amount of 1.0 to 12.5% by weight based on the polymer emulsion latex.