JPH03205333A - Admixture for cement mortar and/or concrete - Google Patents

Abstract

PURPOSE:To improve flexural strength, water resistance and durability of hardened material of cement and to suppress neutralization, comprising latex consisting of polymer fine particles having core.shell type different layer structure and a specific ratio of unsaturated monomer constituting the core part and the shell part. CONSTITUTION:This admixture comprises a polymer latex consisting of polymer fine particles having a core.shell type different layer structure (multi-layer structure wherein inner part in fine particles in polymer latex fine particles is non-rigid and outer part is rigid at a specified temperature) and a weight ratio of unsaturated monomer constituting the core part and the shell part of (90/10)-(10/90) as an essential component. When the weight ratio of unsaturated monomer exceeds 90/10, compression strength, flexural strength and water reducing effects are not sufficiently shown because of destruction of the different layer structure and when the weight ratio of unsaturated monomer <10/90, improving effects of water absorption properties and neutralization suppression are not sufficient.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field] The present invention relates to a durable cement mortar and an additive for durable concrete that essentially contain a polymer latex consisting of core-shell type different stratified polymer particles.

[Conventional technology]

Conventionally, methods have been known in which polymer latex is used as an additive to improve the durability of cement mortar and/or concrete, such as preventing cracking, water resistance, abrasion resistance, chemical resistance, and prevention of carbonation. Although these conventional methods can improve the physical properties and appearance of the hydraulic inorganic composition, they have not yet been able to fully satisfy these performance requirements.

In other words, cement mortar and/or concrete using polymer latex consisting of a homogeneous phase is insufficiently effective in suppressing water absorption and neutralization, which are important indicators for high durability, and is a weak point of the hardened product. The effect of improving the bending strength is also small.

[Problem to be solved by the invention]

Unlike the above-mentioned conventional additives, the present invention uses cement mortar and/or concrete (fine concrete made by hardening cement with water) that has excellent bending strength, water resistance, durability, and prevention of carbonation. The objective is to provide a new additive that provides a hardened cement material (including so-called hardened cement products that do not contain oil aggregate).

[Means to solve the problem]

According to the present invention, the weight ratio of unsaturated monomers having a core-shell type different layered structure and forming the core part and the shell part is 9.
There is provided an additive for cement mortar and/or concrete, which has as an essential component a polymer latex made of polymer fine particles having a particle size of 0/10 to 10/90.

The core-shell type different layered structure in the present invention refers to a multilayered structure in which the inside of the fine particles in the polymer latex particles is soft and the outside is hard at a constant temperature.

The first feature of the polymer latex according to the present invention is that the core
It has a shell-type different stratified structure.

Conventional cement mortar and/or concrete using polymer latex as an additive consisting of a homogeneous phase have poor water absorption and carbonation suppressing effects, and have low bending strength, as described above, but the core/shell according to the present invention Cement mortar and/or concrete containing polymer latex having a different-layered structure has the effect of suppressing water absorption and carbonation, and also greatly improves bending strength. Although the reason for this is not clear at present, it is presumed to be due to the following reason. Generally low Tg
Although the homogeneous polymer latex has good film-forming properties,
Coalescence of particles occurs, which is undesirable. On the other hand, since the core-shell type polymer latex of the present invention has a shell with a high Tg, it is thought that this is because it provides a polymer latex with extremely little coalescence of particles and good film-forming properties.

The second feature of the polymer latex according to the present invention is that the weight ratio of the unsaturated monomers constituting the core part and the shell part is 90/90.
10-10/90, preferably 35/65-90/10
be within the range of

If the weight ratio of the unsaturated monomers that make up the core and shell parts exceeds 90/10, the compressive strength will decrease due to the destruction of the different layer structure.
The bending strength and water reduction effect could not be fully demonstrated, and the
If it is less than 90, the effect of improving water absorption and neutralization suppression will not be sufficient.

-4- The polymer latex, which is an essential component of the cement mortar and/or concrete additive of the present invention, is characterized by the above two points, and more preferably the glass in the shell portion calculated by the polymer latex weight fraction method. Transition point (T
g) is preferably 0 to 50°C, and the Tg of the core portion is preferably 10°C or less.

In general, the Tg of a polymer latex can be determined from the following equation using the weight fraction method if the Tg of a homopolymer of a single unsaturated monomer, which is a structural factor of the polymer latex, is known.

11A: Weight fraction of A precept wB: B u Tg (T) A: Ar &, Tg (absolute temperature) Tg (
T) B: B n (rr) The glass transition point (Tg) of the polymer in the shell part is 0 to 5 as described above.
The temperature is 0°C, preferably 5 to 40°C. If Tg exceeds 50°C, the film forming properties of the polymer will be poor, the binder effect of the polymer will be poor, and furthermore, even if a film is formed, the polymer will become too hard at room temperature, and the effect of improving the bending strength of the cured cement product will be small. Improvements in water absorption and neutralization are also not sufficient. Tg is O'
If it is less than C, the effect of reducing water consumption/C is insufficient.

Further, the polymer latex used in the present invention preferably has a crosslinked structure inside the polymer particles in order to improve the strength and water resistance of the cured cement product.

The present invention will be explained in more detail below.

The polymer latex, which is an essential component of the cement mortar and/or concrete additive of 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), methacrylic esters (e.g., methyl methacrylate, ethyl methacrylate), , butyl methacrylate, octyl methacrylate), styrenes such as styrene and α-methylstyrene, dienes such as butadiene and -7-isoprene, vinyls such as ethylene, vinyl acetate and vinyl propionate, acrylonitrile, α −
Examples include nitriles such as methylacrylonitrile, but in order to obtain cement mortar and/or concrete with excellent durability and weather resistance, it is desirable to use (meth)acrylic acid esters.

The unsaturated monomers mainly used in the core part are ethyl acrylate, butyl acrylate, octyl acrylate, and 2-ethylhexyl acrylate, and particularly preferably ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. is used.

The unsaturated monomers mainly used in the shell portion are methyl methacrylate, ethyl methacrylate, and butyl methacrylate, and methyl methacrylate is particularly preferably used.

Further, in order to improve the dispersibility of the cement, it is more preferable to use a copolymerized unsaturated monomer having a carboxyl group and an ethylenic double bond in the molecule for the shell portion. Examples of such unsaturated monomers having a -8-carboxyl group and an ethylenic double bond in the molecule include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, and half esters thereof; Examples include hafamide and salts thereof, but it is particularly preferable to copolymerize methacrylic acid in an amount of 0.1 to 5% by weight with respect to the unsaturated monomer of the shell portion.

Furthermore, in order to improve strength and water resistance, it is preferable to copolymerize a crosslinking agent having a plurality of functional groups in one molecule in the core part and shell part.

Examples of these crosslinking agents include trimethylolpropane triacrylate, glycidyl acrylate, glycidyl methacrylate, bisphenol A polyoxyethylene adduct di(meth)acrylate, triallylisocyanurate, and N-methylolacrylamide. 0.1 to 5% by weight of acrylate based on the unsaturated monomer in the core and/or shell part
It is preferable to copolymerize and use.

The polymer latex most preferably used in the present invention has a core-shell type different layered structure, and the weight ratio of the unsaturated monomers constituting the core part and the shell part is 35/65 to 90/1.
The weight composition of the unsaturated monomer in the core part is 0 to 5% by weight of a crosslinking agent, and the weight composition of the unsaturated monomer in the shell part is 0 to 5% by weight. Weight is an essential prestige.

This is because such polymer latex can reduce the amount of water (11/C) used when mixing concrete, and can also improve the durability, weather resistance, and carbonation prevention ability of hardened concrete. This is because it is effective.

As the emulsifier for emulsion polymerization of the polymer 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? ■: Alkyl group A of 06 to 2o: -C}I2CH2- or -CH2-(Jl-C
H3 n: O-100 preferably 5 to 40 M1: Monovalent or divalent cation (2) polyoxyalkylene alkyl ether sulfate salt Rx -0-+AO) n-SO3M1 (wherein R1, A. n and A■ is the same as above) １■１
- (3) Polyoxyethylene alkylaryl ether ether sulfate salt? 1-Q(HAO)rIS03M■ 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 (in the formula, M1+AtntR2 and R3 are the same as above) (wherein M1+AlnlR2 and R3 are the same as above) (wherein M11AlnlR2 and R3 are the same as above) (wherein M11AlnlR2 and R3 are the same as above: 0,1 R4: CH2- , CH2CH2 or phenyl group (MilAlnlmlR2 1R3 and R4 are the same as above)? Representative examples of nonionic emulsifiers] (10) Polyoxyalkylene alkylaryl ether R2-QO-+ao) PH (wherein p is O-100 Preferably 5-70, R2, A
is the same as above) (1l) Polyoxyalkylene alkyl ether R ■ 10 → AO) pH (In the formula, R1, A and p are the same as above) These anionic emulsifiers and nonionic emulsifiers are each used singly or in combination of two or more Although they can be used in combination, it is preferable to use one or more emulsifiers having ethylene oxide and propylene oxide groups in the molecule. More preferably, the compound (1) is used as an anionic emulsifier, and the compound (10) or (11) is used as a nonionic emulsifier.
It is preferable to use ``separate''.

In addition, these emulsifiers have a ratio of 0.5 to 1 with respect to the unsaturated monomer.
The amount is preferably 5% by weight, preferably 1 to 10% by weight. 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'-asobis(2-aminodipropane) and its salts, 2,2'-asobis( N,
N'-dimethylene-isobutyramidine) and its salts, 4
, 4'-azobis (4-cyanovaleric acid) and its salts can be used. In the preparation of the polymer latex used in the present invention, it is preferable to use the above-mentioned water-soluble azo initiator in an amount of 0.1 to 3 weight 2 of the unsaturated monomer mixture.

The polymer latex used in the present invention can be prepared by the following general emulsion polymerization method using the above-mentioned unsaturated monomer, emulsifier, and polymerization initiator.

That is, after dissolving an emulsifier in the aqueous phase and solubilizing a portion of the core unsaturated monomer, a polymerization initiator is added, and then the core unsaturated monomer and shell unsaturated monomer are dissolved. Emulsion polymerization can be prepared by either the monomer dropping method, in which an emulsifier, a portion of water, and an unsaturated monomer are mixed and emulsified in advance and added dropwise.However, there are drawbacks to emulsion polymerization. It is more preferable to use the pre-emulsification method in order to reduce the amount of the polymer adhering to the polymerization pot or stirring blade. In particular, when producing a polymer latex with a core-shell type different layered structure, it is important to note that the polymerization of the core part and the polymerization of the shell part form a block-type combination, and therefore, the polymerization of the core part ends. Afterwards, it is preferable to carry out aging for several minutes to several hours. The polymer latex used in the present invention has a solid content of 40 and a viscosity of 10 to 1000 c at 2 weight.
p (Pluckfield type viscometer), which has good workability, and which has a low viscosity and can contain a solid content of 50% or more.

Furthermore, these polymer latexes used in the present invention have an average particle size of less than 200 nm, preferably 500 nm.
It is more preferable to keep the thickness below 2000 nm. If the particle size is 2000 nm or more, the strength, weather resistance, durability, water resistance, and carbonation of cement mortar and/or concrete will be insufficiently improved, and the use of the cement mortar and/or concrete will be insufficient compared to particles with a small particle size. This is not preferable because the amount increases.

The amount of polymer latex mixed into cement and/or concrete is 0.3 to 12 weight 2 as solid content, preferably 0.5 to 10 weight 2 . 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 the weight exceeds 12 da, the compressive strength, which is a characteristic of hardened cement, decreases, which is undesirable.

Further, in the present invention, in order to further improve fluidity and durability, it is desirable to blend a sulfonic acid group-containing polymer at the time of blending the hydraulic inorganic material and the polymer latex. In this case, the sulfonic acid group-containing polymer may be blended into the polymer 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
- It's out of place. 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 5,000 to 5
It is 0,000. The blending amount of this polystyrene sulfonate is 0. The Ol weight is preferably 2 to 4.0 weight Da, more preferably 0.1 weight 2 to 2.0 weight 2. If it is less than 0.01 weight z, 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 weight z, 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, durability can be further improved by using together with a frame material such as particulate silica (silica fume), fly ash, or blast furnace slag, among which silica fume is particularly excellent. Silica fuum is effective even when added in powder form, but when it is kneaded in advance with the polymer latex of the present invention, there is no aggregation of silica fume, both materials are uniformly dispersed, and the durability of the polymer cement is significantly improved. The particle size of silica fume is the primary particle size of 0.11 or less, and the secondary particle size of partially aggregated particles is 1.
(17 m - 100 pm (7)), and SiO2 purity of 70% or more is preferred.

Furthermore, in the present invention, reinforced cement mortar and/or
Alternatively, in order to further improve the durability of concrete, it is effective to use a rust preventive agent together. Rust inhibitors that can be used in combination include nitrites, chromates, silicates, phosphates, organic phosphates, amines, alkylphenols, mercabutanes, and nitro compounds, but the polymer latex of the present invention By using together with an organic phosphate rust preventive agent and more preferably a 1-hydroxyalkane-1,1-diphosphonate such as 1-hydroxyethane-1,1-diphosphonate, commercially available nitrites can be improved. A remarkable durability improvement effect can be obtained at a relatively low concentration.

119- Also, in carrying out the present invention, nonionic and anionic polymeric substances, coloring pigments, chelating agents, preservatives, pH adjusters, plasticizers, early hardening agents, and slow hardening agents may be used as necessary. , conductive (antistatic) agents, body materials (white earth), and reinforcing agents may be used as auxiliary additive components.

〔effect〕

By using the additive of the present invention, the cement mortar and/or concrete obtained has improved bending strength, improved water resistance (water absorption suppression ability), and furthermore, the amount of water used can be reduced and carbonation suppressed. It has extremely high practical value because it allows for

Therefore, the cement mortar and/or concrete additive of the present invention can be used as a base material for inner and outer walls of building structures, adhesives for tiling, joint materials for tiling, flooring materials, anticorrosive lining materials such as anticorrosive ACL reinforcing bars, etc. Waterproofing materials for water storage tanks, pools, silos, tennis court bases, etc., deck strength barring materials for ship decks, pedestrian bridge floors, bridge decks, etc., acid-resistant fume pipes, special concrete moldings for GRC products, pass terminals, tunnel interiors, etc. , Semi-rigid roads in factories, etc., spraying protective coating materials for mortar and concrete structures using inorganic and organic fibers such as glass fiber, carbon fiber, polyester fiber, and polyvinyl alcohol fiber, carbon fiber, and metal powder (flake). Conductive coating materials, electromagnetic shielding materials, ultra-high strength products, heavy-duty anti-corrosion coating materials for ship ballast tanks, mortar floating repair materials, cable-stayed bridge wire materials, cosmetic bottles, etc.
It exhibits extremely efficient performance when used in manufacturing certain types of chemical products such as interlocking.

〔Example〕

Next, in order to explain the present invention in more detail, examples are shown below, and the method for preparing the polymer latex and the performance evaluation method common to each example are summarized below.

(1) Preparation of polymer latex i) Sample & 1 In a glass reaction vessel equipped with a thermometer, stirrer, reflux condenser, nitrogen introduction tube and dropping funnel, add 6.0 parts by weight of the emulsifier (N of Table 1) and Pour 150 parts by weight of water and dissolve.
The inside of the system was replaced with nitrogen gas. Separately, for the unsaturated monomer mixture shown in &1 of Table 2, first, 90.0 parts by weight of the unsaturated monomer mixture for the core part was prepared, and 7.5 parts by weight of this was added to the reaction vessel at 50°C. Emulsification was performed for 10 minutes. Then, after raising the temperature to 60°C, 2,2'-azobis(N
, N'-dimethyleneisobutyramidine) hydrochloride (V
A-044) 9. OX 10-3+ole/water phase was dissolved in 50.0 parts by weight of water and added to the reaction vessel, and the remaining unsaturated monomer was immediately poured into the reaction vessel continuously for 18 minutes. It was added dropwise and polymerization was carried out at 60°C.

After dropping the unsaturated monomer for the core part, the mixture was incubated at 60°C for 10 minutes, and then 60 parts by weight of a separately prepared unsaturated monomer mixture for the shell part was continuously added into the reaction vessel for 12 minutes. It was added dropwise and polymerization was carried out at 60°C. After dropping the unsaturated monomer, it was aged at 60° C. for 90 minutes and cooled to room temperature to prepare sample Nα1.

■) Samples Nn2~Nα7, &13~&18, Nα20~
Nα21 was prepared according to sample Nnl using the combination of the emulsifier shown in Table 1 and the unsaturated monomer shown in Table 2, and the core-shell ratios shown in Tables 4, 5, 6, and 7. Here, the dropping time of the unsaturated monomer in the core part and the shell part is 30 minutes in total,
It was divided proportionally according to the weight ratio.

City) Samples Nα8 to Nα10 Emulsifier &1 in Table-1 and unsaturated monomer mixture N in Table-2
Using α10 to NQ12, the entire amount was continuously dropped over 30 minutes to obtain a uniform polymer latex.
Adjusted according to 1.

tv) Sample NCLll After adjusting the homogeneous polymer latexes of samples Nα9 and Nα10, they were mixed and stirred to a weight ratio of 60/40 to make them homogeneous.

■) Sample Nα19 CT emulsion (manufactured by Dainippon Ink & Chemicals), which is a commercially available acrylic polymer latex for polymer cement, was used as it was.

vi) Sample Nα12 No polymer latex added (Brain) Table 1: Emulsifier composition (vi) Confirmation of heterolayer formation of polymer latex The production of the heterolayer polymer latex was confirmed by the following method.

Immediately after adding the unsaturated monomer to the core part of the sample Ncil and aging, half of the polymer latex of the sample was extracted,
The mixture was stirred at 60° C. for 45 minutes, and then cooled to obtain a core polymer latex. Half of the unsaturated monomer in the shell portion was continued to be added dropwise to the remaining half, and after the addition was completed, the mixture was aged at 60° C. for 1 hour and cooled to obtain a core-shell polymer latex. The particle size of each polymer latex produced was measured using a submicron particle size analyzer (Coulter Mo
del N4 type). The results are shown in Table-3.

Table 3 -26- The average particle diameter of core-shell polymer latex is larger than that of core-only polymer latex, and the value was determined from the weight ratio of the unsaturated monomers in the core and shell parts. It is almost equal to the calculated value (98 nm), and the particle size distribution is a single peak with no change, which indicates that the particle size is indeed different layered.

(2) Glass transition point (Tg) The glass transition point (Tg) of the polymer latex was determined from the Tg of the raw monomers butyl acrylate, ethyl acrylate, methyl methacrylate, and methacrylic acid using the following formula.

A, B, Tg (T) ethyl acrylate C + Tg (T) methyl methacrylate D Tg (T) methacrylate C. D: Weight ratio of each component (A+B+C+D=1.0)-
27- In addition, Tg (T) of butyl acrylate = 2186 K, Tg (T) of ethyl acrylate = 249' K, Tg (T) of methyl methacrylate = 378 ° K, Tg (T) of methacrylic acid = 501 °K was used.

(3) 30 g of polymer latex adjusted to have a solid content of 40% by weight was uniformly cast onto a 12cm x 14cm glass plate, and air-dried at 25°C. The film thus obtained was cut into 2 cm x 4 cm pieces and heated at 20°C.
Soaked in a petri dish filled with benzene for 48 hours,
The film was evaluated based on the degree of swelling and solubility as shown below.

O: Film area before immersion in benzene (2cm x 4cm
) or slightly swollen.

Δ: The degree of swelling is large and the film shape is impaired.

×: The film was dissolved in benzene and became a uniform liquid.

(4) Performance evaluation The polymer latex prepared as above was evaluated using it as an admixture for polymer cement. i) Adjustment of polymer cement Ordinary Boltland cement 1 kg Yamasand (produced in Kisarazu) 2 kg Antifoaming agent ( Non-ionic) Ig polymer latex 150
g (solid content: 60g) and flow value (JISR52
Necessary water was added so that 01) was 180±10, kneaded with a paddle mixer, and the kneaded properties were measured. Furthermore, the kneaded material is placed in a formwork (4.Ox 4.Ox 16.Oan
), and after 2 days, demolding and curing, the cured product was subjected to performance evaluation.

For comparison, sample Nα10 (plain) prepared in the same manner except that it did not contain polymer latex was used.

■) Evaluation of polymer cement The kneading properties and performance of the cured product were evaluated according to the following method.

■Kneading properties/unit volume weight; JISA1116 ・W/C; water usage/cement weight x 100 ■Hardened body performance/bending strength test; JIS R 5201・Compressive strength test; JIS R 5201・Adhesive strength test; JIS
A 6915・Water absorption test; JIS A 1404・Abrasion test; JIS A 1451・Drying shrinkage test; JIS A 1129・Neutralization test; 4X4X16
A rectangular parallelepiped specimen was cured for one week at 20°C and 80% RH, left in a pressurized autoclave with a CO2 concentration of 5% and 1 kg/cd for 3 months, and the specimen was removed. 1z phenolphthalein alcohol solution was sprayed onto the cut surface, the area of the part where the red color disappeared was measured, and the neutralization rate was calculated as a percentage of the total cross-sectional area.

[Example 1] The effect of different layers of polymer latex was investigated in a polymer cement system. The results are shown in Table 4. Sample Nα1-7
is the present invention, and Nα8-12 are comparative examples.

In samples Nα1 to Nα7 with different layers of polymer latex,
It is an indicator of kneading properties and high durability polymer cement.
The water absorption rate, abrasion resistance, carbonation rate, and drying shrinkage are all small and good.Furthermore, the bending strength and adhesive strength are large and good, and the decrease in compressive strength is small.

On the other hand, sample No. using a uniform emulsion. 8-10
, homogeneous polymer latex using unsaturated monomers in the core and shell parts of sample Nal (sample Nos. 9 and 10).
) was simply mixed. 1. Although the performance of Sample No. 1 may be improved in some physical properties compared to the plane of Sample N (112), it is not possible to satisfy the above-mentioned physical properties at the same time.

[Example 2] Using the Ncil emulsifier shown in Table 1, the core/shell ratio was set to 6.
The effect of rg was examined when it was kept constant at 0740. The results are shown in Table-5.

133- JP-A-3 205333 (13) [Example 3] An emulsifier with Nα1 in Table 1 and an unsaturated monomer with an unsaturated monomer composition of Nα1 in the core and shell parts as shown in Table 2. The performance as a polymer cement was evaluated using polymer latexes having the same composition ratio but varying the ratio of the core part to the shell part as shown in Table 6.

The results are shown in Table-6.

Sample N (11, 15, 16 are examples of the present invention, sample N [
Samples 117 and 18 are comparative examples, and for comparison, a commercially available acrylic polymer latex for polymer cement was used as sample Nn19.

If the ratio of the core part is too high, layer destruction occurs and various performances deteriorate (sample N (117)). Also, if the ratio of the shell part is too high, the expression of the different layering effect is small (sample Nα18).

By selecting an appropriate core-shell ratio (sample Nα1, 15
, 16), it can be seen that the various performances are greatly improved compared to the commercially available comparative example.

-35- [Example 4] Using the emulsifier Nα1 in Table 1 and the unsaturated monomer in Table 2, the influence of the polyfunctional crosslinking agent on the performance of polymer cement was investigated. The results are shown in Table-7.

137-JP-A-3 205333 (17) [Example 5] Using sample Nα1 as a base, silica fume as a frame material,
The effect of combined use with calcium polystyrene sulfonate, a high performance water reducing agent, and aluminum 1-hydroxyethane-1,1-diphosphonate and calcium nitrite, which are rust preventive agents, was investigated. The antirust effect was measured according to JISA6205, and the evaluation was visually judged based on the following criteria.

O・No rust at all O: Slight rust Δ: Approximately half of the area is covered with rust X: Rust occurs on 7-81#l XX: Entirely rusted The results are shown in Table-8.

Samples &1 and Na22 to NQ25 are examples of the present invention, and sample Nα12 is a comparative example.

By further using silica fume or calcium polystyrene sulfonate in the heterolayered emulsion, it is possible to further improve the water absorption rate and neutralization, which are measures of high durability, and also increase the bending strength. In addition, even when used in combination with a rust preventive agent that suppresses the occurrence of rust, which is one of the main factors in the deterioration of mortar (concrete), the occurrence of rust can be prevented without reducing the effects of the present invention on water absorption, carbonation rate, bending strength, etc. It can be suppressed.

In particular, compared to calcium nitrite, which accounts for most of the commercially available rust preventives, it can be seen that when used in combination with an organophosphorus rust preventive agent, which is 1-hydroxyethane-1,1-diphosphonate, a small amount can exhibit a remarkable rust preventive effect.

-39- Table-8

Claims (4)

[Claims] (1) It has a core-shell type different layered structure, and the weight ratio of the unsaturated monomers constituting the core part and the shell part is from 90/10 to
An additive for cement mortar and/or concrete that contains a polymer latex made of fine polymer particles having a ratio of 10/90 as an essential component. (2) It has a core-shell type different layered structure, and the weight ratio of the unsaturated monomers constituting the core part and the shell part is 35/65 to 9.
0/10, and the weight composition of the unsaturated monomer in the core is 55 to 100% by weight of an acrylic acid alkyl ester in which the number of carbon atoms in the alkyl group is 1 to 8.The number of carbon atoms in the alkyl group methacrylic acid alkyl ester having 1 to 4 0 to 45% by weight crosslinking agent 0
~5% by weight, and the weight composition of the unsaturated monomer in the shell portion is 5 to 49.9% by weight of an acrylic acid alkyl ester whose alkyl group has 1 to 8 carbon atoms.The alkyl group has 1 to 8 carbon atoms. 45-90% by weight of methacrylic acid alkyl ester of ~4, 0.1-5% of ethylenically unsaturated carboxylic acid or salt thereof, 0-5% of crosslinking agent, and/or a cement mortar containing as essential components a polymer latex of Additive for concrete. (3) Glass transition point (T
The additive for cement mortar and/or concrete according to claims (1) and (2), characterized in that g) is 0 to 50°C, and Tg of the core portion is 10°C or less. (4) The additive for cement mortar and/or concrete according to claims (1) to (3), wherein the polymer fine particles have a crosslinked structure.