JPH0226855A - cement composition - Google Patents

Abstract

PURPOSE:To reduce a degree of delay of setting of a mortar and to improve the elasticity of the mortar by incorporating a specified resin emulsion into cement. CONSTITUTION:A resin emulsion(B) contg. 20-300 pts.wt. ethylene/satd. carboxylic acid vinyl ester component per 100 pts.wt. acrylic resin component is obtd. by carrying out emulsion copolymn. by compressing ethylene to >=20kg/ cm<2>G and maintaining a concn. of the satd. carboxylic acid vinyl ester at <=5wt.% in the presence of an acrylic emulsion having <=0 deg.C glass transition point obtd. by an emulsion polymn. of >=60wt.% (meth)acrylic ester monomer having 1-18C alkyl group with <=40wt.% copolymerizable monomer, in an aq. medium in the presence of an emulsifier and a radical polymn. initiator. 35-200 pts.wt. (B) expressed in terms of solid resin content is mixed with 100 pts.wt. cement (A).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cement composition, more specifically, an acrylic ester monomer having an alkyl group having 1 to 18 carbon atoms and/or an acrylic ester monomer having an alkyl group having 1 to 18 carbon atoms. 100 weight acrylic resin components obtained by emulsion copolymerization of ethylene and saturated carboxylic acid vinyl ester in the presence of an acrylic emulsion with a glass transition temperature of 0°C or less obtained by emulsion polymerization of methacrylic acid ester monomers. An emulsion in which the proportion of ethylene and saturated carboxylic acid vinyl ester copolymer components is 20 to 300 parts by weight, and the resin solid content is 35 to 100 parts by weight of cement.
It relates to a cement composition characterized in that it contains ~200 parts by weight.

B'(7)' Methods have been proposed to improve physical properties such as strength and water resistance of cement products by incorporating various synthetic resin emulsions, and to improve workability when manufacturing the cement products. There is.

For example, Special Publication Publication No. 39-2614, Special Publication No. 42-20078
The issue states that adding vinyl acetate emulsion to cement improves the workability and strength of cement mortar.
Furthermore, Japanese Patent Publication No. 42-20078 discloses that adding a vinyl acetate ethylene copolymer emulsion improves the alkali resistance and water resistance of cement mortar compared to when vinyl acetate emulsion is used.
When vinyl acetate-ethylene-methyl methacrylate copolymer emulsion is added to No. 31, alkali resistance,
A cement product with excellent weather resistance, heat resistance, adhesive strength, tensile strength, bending strength, compressive strength, impact strength, abrasion resistance, etc. comparable to that of conventional ethylene-vinyl acetate copolymer emulsion can be obtained. No. 57-43546 improves freeze-thaw stability by adding a terpolymer emulsion obtained by emulsion copolymerization of vinyl acetate, noralbutyl acrylate, or 2-ethylhexyl acrylate under ethylene pressure. It is proposed to do so.

Further, JP-A-57-61653 describes that workability is improved by adding an emulsion obtained by emulsion polymerization of an acrylic ester in the presence of a vinyl acetate-ethylene copolymer emulsion.

The methods described above have been actually adopted and have achieved a certain amount of success.

In recent years, various demands have been made on the performance of cement products, one of which is the provision of elasticity. In other words, in the paving and construction industries, it is necessary to prevent cracks from forming in thick molded bodies, to ensure that the base material can follow the expansion and contraction caused by temperature changes, and to have the property that molded bodies can bend. It is strongly requested.

However, the above-mentioned proposals all involve adding a relatively small amount of synthetic resin emulsion to cement to cause the cement to harden in a nearly ideal manner, so to speak, to fully express the inherent properties of cement. Therefore, if a cement molded body is made thicker, cracks are likely to occur, and furthermore, the conformability to the base and the flexibility of the molded body cannot be expected.

C9 recommends that in order to obtain a cement composition with excellent superelasticity, it is not enough to simply increase the content of the synthetic resin emulsion, but in emulsions other than those of the present invention, it is necessary to increase the content of the synthetic resin emulsion. Problems arise with miscibility and cement hardening retardation, making it difficult to put it to practical use.

In other words, in ethylene-vinyl acetate copolymer emulsion, cement hardening retardation is small even if the amount added is large;
The desired elasticity cannot be obtained, and acrylic emulsions not only have a large curing retardation but also have the disadvantage of producing a large off-odor when added to cement.

Furthermore, terpolymer emulsions obtained by emulsion copolymerization of vinyl acetate and acrylic esters under pressure with ethylene also tend to delay cement hardening, which is problematic.

In addition, in the presence of ethylene-vinyl acetate copolymer emulsion,
Like acrylic emulsions, emulsions obtained by emulsion polymerization of acrylic esters also have problems in retardation of cement hardening.

03 Steps to Solve the Problem The present inventors have conducted intensive studies on cement compositions with excellent elasticity, and have discovered that excellent elasticity can be obtained by adding a specific amount of a specific emulsion to cement. The present invention has now been completed.

That is, the present invention provides an acrylic ester monomer having an alkyl group having 1 to 18 carbon atoms and/or an acrylic ester monomer having 1 to 18 carbon atoms.
- Emulsion copolymerization of ethylene and saturated carboxylic acid vinyl ester in the presence of an acrylic emulsion with a glass transition temperature of 0° C. or less obtained by emulsion polymerization of a methacrylic acid ester monomer having ~18 alkyl groups, Containing an emulsion in which the proportion of ethylene and saturated carboxylic acid vinyl ester copolymer component is 20 to 300 parts by weight per 100 parts of acrylic resin component is 35 to 200 parts by weight as resin solid content per 100 parts by weight of cement. A cement composition characterized by:

The acrylic emulsion in the present invention has 1 to 18 carbon atoms.
Acrylic acid ester monomer and/or carbon number 1-1
It is an emulsion obtained by emulsion polymerization of the methacrylic acid ester monomer No. 8, and the glass transition temperature (T
g) The temperature of the emulsion must be below h'O°C, preferably below -10°C.

This is because if Tg exceeds 0°C, a cement molded product with excellent elasticity cannot be obtained.

Examples of acrylic esters having 1 to 18 carbon atoms include methyl acrylate, ethyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, hebutyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, and acrylic acid. Examples include decine, lauryl acrylate, and stearyl acrylate, and examples of methacrylic esters having 1 to 18 carbon atoms include methyl methacrylate, ethyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, and 2-ethylhexyl methacrylate. , dodecyl methacrylate, lauryl methacrylate, stearyl methacrylate, etc., and particularly preferred are acrylic esters having 4 to 12 carbon atoms and 1 carbon number.
A mixture of ~4 methacrylic esters is used.

Further, it is desirable that the total amount of acrylic ester and methacrylic ester monomers is 60% by weight or more;
If it is less than 0% by weight, a cement molded product with excellent elasticity cannot be obtained no matter how the polymerization conditions of ethylene and vinyl acetate are changed.

□Other monomers copolymerizable with these monomers may also be used, such as unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid, acrylamide, and N-methylol. Unsaturated carboxylic acid amides such as acrylamide, N-butoxymethylacrylamide and diacetone acrylamide, epoxy group-containing vinyl monomers such as glycidyl acrylate and glycidyl methacrylate, or 2-hydroxyethyl acrylate, 2
- Hydroxy group-containing monomers such as hydroxypropyl acrylate and 2-hydroxyethyl methacrylate,
Examples include vinyl monomers such as styrene, acrylonitrile, vinyl acetate, and vinyl chloride.

The acrylic emulsion of the present invention can be obtained by subjecting the monomers to emulsion polymerization in an aqueous medium, if necessary in the presence of an emulsifier, using a radical polymerization initiator.

In the present invention, an acrylic acid ester monomer having an alkyl group having a carbon number of t-ta and/or a carbon number of 1-1
Emulsion copolymerization of ethylene and saturated carboxylic acid vinyl ester in the presence of an acrylic emulsion with a glass transition temperature of 0°C or less obtained by emulsion polymerization of a methacrylic acid ester monomer having 8 alkyl groups, and acrylic By setting the ratio of the ethylene and saturated carboxylic acid vinyl ester copolymer component to 100 parts by weight of the resin component to be 20 to 300 parts by weight, an emulsion can be obtained that provides a cement composition with a small cement hardening delay and excellent elasticity.

If the ratio of the ethylene-saturated carboxylic acid vinyl ester copolymer component is less than 20 parts by weight based on 100 parts by weight of the solid content of the acrylic emulsion, cement curing is likely to be delayed, and if it exceeds 300 parts by weight, the elasticity may deteriorate. Therefore, it is difficult to obtain a cement composition with excellent properties.

Regarding the emulsion copolymerization conditions of ethylene and saturated carboxylic acid vinyl ester in the present invention, the following conditions should preferably be adopted.

That is, in the presence of an acrylic emulsion, 2
0 kg/cm”G or more, preferably 30 kg#m”
Pressurize to a pressure of G~100kg/c@''G, and reduce the amount of saturated carboxylic acid vinyl ester monomer in the polymerization system to 5% by weight.
Polymerization is carried out by continuously or intermittently replenishing the polymerization system as described below. ethylene pressure 20
kg/am" below 0, or when the a degree of the saturated carboxylic acid vinyl ester monomer during polymerization exceeds 5% by weight,
The elasticity of the cement molded body decreases.

In the emulsion copolymerization of ethylene and saturated carboxylic acid vinyl ester of the present invention, a radical polymerization initiator, a PHIm stabilizer, an emulsifier and/or a dispersant such as a protective colloid, and a polymerization chain transfer agent are used as necessary.

The radical polymerization initiator in the present invention is a water-soluble radical initiator used in ordinary emulsion polymerization, such as hydrogen peroxide, potassium persulfate, sodium persulfate, am7nium persulfate, tert-butyl hydroperoxide, etc. Alternatively, a redox system in combination with a reducing agent such as L-ascorbic acid, sulfite, Rongalite, or ferrous sulfate is used.

Suitable dispersants for emulsion polymerization used in the present invention are nonionic surfactants and/or anionic surfactants. Moreover, various water-soluble polymers can also be used as protective colloids.

Examples of the nonionic surfactant of the nonionic dispersant used in the present invention include polyoxyethylene lauryl ether, polyoxyethylene octylphenol ether,
Polyoxyethylene alkyl ether and polyoxyethylene alkyl phenol ether such as polyoxyethylene sorbitanyl phenol ether, polyoxyethylene sorbitan fatty acid ester such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, ethylene oxide addition 11
Examples include 0 to 80% polyoxyethylene polyoxine propylene block copolymer.

Examples of anionic surfactants used in the present invention include sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dialkylsulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkylphenol ether sulfate,
Examples include sodium vinyl sulfonate.

Further, examples of the protective colloid include polyvinyl alcohol, partially saponified polyvinyl alcohol, fibrous derivatives such as methyl cellulose, and hydroxyethyl cellulose.

The PHR regulator used in the present invention includes hydrochloric acid,
Acids such as phosphoric acid, acetic acid, succinic acid, boric acid, and carbonic acid and their salts, bases such as alkali metal hydroxides, aqueous ammonia, and amines are used.

In the present invention, the emulsion obtained as described above has a resin solid content of 35 to 2 parts by weight based on 100 parts by weight of cement.
00 parts by weight, preferably 40 to 100 parts by weight. If the content is outside these ranges, a cement molded body with good elasticity cannot be obtained. That is, if the content of the emulsion of the present invention is less than 35 parts by weight as a solid content with respect to 100 parts by weight of cement, the cement molded product will lack elasticity and no flexibility will be obtained;
If the amount exceeds 0.00 parts by weight, the surface of the cement forming body becomes sticky, making it easy to stain, which is not preferable.

In the cement composition of the present invention, in addition to cement, sand, silica sand, and inorganic filler are used as aggregates as necessary. The blending amount of such aggregate also affects the physical properties of the cement molded body, so consideration must be given. Although it varies depending on the viscosity and shape of the aggregate, it is preferably mixed in an amount of 50 to 300 parts by weight per 100 parts by weight of cement.

Antifoaming agents commonly used in the cement compositions of the present invention,
Even if water reducing agents, AE agents, anti-corrosion agents, setting retarders, setting accelerators, etc. are added, no problem will arise.

01 Actions and Effects By using the emulsion obtained by emulsion copolymerization of ethylene and saturated carboxylic acid vinyl ester in the presence of the acrylic emulsion of the present invention, a cement composition with small mortar hardening delay and excellent elasticity can be obtained. is obtained.

As mentioned above, the effects of the present invention include acrylic emulsion,
A tertiary copolymer emulsion obtained by emulsion copolymerization of vinyl acetate and acrylic acid ester under ethylene pressure cannot satisfy all requirements, and a mere emulsion of an acrylic emulsion and an ethylene-vinyl acetate copolymer emulsion cannot be obtained. Even with a blend, it is difficult to obtain the forward motion of the present invention, and emulsion polymerization of an acrylic ester monomer having an alkyl group having 1 to 18 carbon atoms and/or a methacrylic ester monomer having an alkyl group having 1 to 18 carbon atoms is used. Emulsion copolymerization of ethylene and saturated carboxylic acid vinyl ester in the presence of an acrylic emulsion with a glass transition temperature of 0° C. or less obtained by This can only be achieved by using a proportion of the combined components of 20 to 30 parts by weight. The reason for this is not clear, but it is thought that the above performance is due to the formation of graft products of ethylene and vinyl acetate with high radical reactivity to the acrylic resin, and the formation of low molecular weight ethylene-vinyl acetate copolymers. It will be done.

The present invention will be explained in more detail below by giving Examples and Comparative Examples.

Example! In a reactor equipped with a stirrer, 1011 parts of water, 3 parts of nonylphenol added with 20 moles of ethylene oxide, 0.5 part of sodium dodecylbenzenesulfonate, and acrylamide (A
M) Add 1 part. Next, 20% of the total amount of a mixture of 86 parts of 2-ethylhexyl acrylate (2-EHA), 13 parts of methyl methacrylate (MMA), and 2 parts of acrylic acid (AA) was added, and ammonium persulfate was added at 65°C. Polymerization was carried out using The remaining 80% of the mixed monomers were uniformly added over 4 hours after the start of polymerization to obtain an acrylic emulsion (1). The glass transition point (Tg) was determined to be -55°C by DSC.

Next, 100 parts of the emulsion resin was transferred to a pressure-resistant autoclave, and 50 parts of a 0.5% polyvinyl alcohol aqueous solution and 1 part of nonylphenol added with 20 moles of ethylene oxide were added.Next, 7 parts of vinyl acetate (V
Ac) was added and the ethylene pressure was 50 kg/am at 50°C.
'' and polymerization was initiated using ammonium persulfate and Rongalite.Then, the concentration of vinyl acetate in the polymerization system was analyzed by iodometry, and 28 parts of vinyl acetate was continuously added so that the concentration was 2 to 3%. The ethylene pressure was kept constant during this period.

The resulting emulsion had a ratio of ethylene-vinyl acetate copolymer to acrylic copolymer of 50:100 based on solid content concentration and NMR analysis.

Next, using this emulsion, a cement molded product was created by the following method, and its physical properties were evaluated. The results are shown in Table 1.

Cement molded product evaluation method> O Creation of cement molded product Emulsion/cement/silica sand = 0.5/1/l (
JIS A6G21 (solid content weight ratio)
The coating material (roof waterproofing coating material) was poured into a specified mold to a specified thickness at 20°C under an atmosphere of 65% RH, and after 48 hours had elapsed, the mold was removed and cured for an additional 12 days.

1. Impact resistance: A 2cm thick cement molded product is tested using a DuPont impact tester and evaluated based on the following criteria.

◎　;　No abnormality at all.

O: Slightly deformed.

△: Cracks appear.

2. Flexibility: The bendability of cement molded bodies with a thickness of 2+nm and 3cm in a cylinder with a diameter of 5cm is evaluated according to the following criteria.

◎　;　No abnormality at all.

O: There is almost no abnormality.

×; Cracks appear.

×X: Large crack.

3. Adhesion to the substrate (adhesive force); emulsion/cement/silica sand = 0.5/l/l (
A cement composition with a mixing ratio of
Rut) Cured for 114 days. JIS A69
Measured according to No. 111 Adhesion Strength Test.

4. Presence or absence of lIP conversion delay; In the section of creating a cement molded product, observe the hardening state when demolding after 48 hours to determine the presence or absence of curing delay.

Example 2 100 parts of the resin content of the acrylic emulsion (1) obtained in Example 1 was added to a pressure-resistant autoclave, and 100 parts of a 2% aqueous polyvinyl alcohol solution and 3 parts of ethylene oxide were added.
Add 2 parts of 0 mole added nonylphenol. Next, 5 parts of vinyl acetate and 5 parts of Veova-100 (trade name of Shell) were added, and the ethylene pressure was 50 kg/a at 60°C.
Polymerization was initiated using hydrogen peroxide and Rongalit. Next, 30 parts of vinyl acetate and Veova
A mixture of 30 parts of -10(H) was continuously added so that the concentration of these vinyl esters in the polymerization system was 4% to advance the polymerization.

According to NMR analysis of the obtained emulsion, the ratio of ethylene-vinyl ester copolymer to acrylic copolymer was 100.
: It was 100.

A cement molded body was prepared using this emulsion in the same manner as in Example 1, and its physical properties were evaluated. The results are shown in Table 1.

Example 3 Resin content of acrylic emulsion obtained in Example 1: 10
Polymerization was carried out in the same manner as in Example 1, except that the vinyl acetate monomer concentration during the polymerization in Example 1 was kept at 10% instead of 2 to 3%, and an emulsion was obtained. The ratio of ethylene vinyl acetate copolymer to acrylic copolymer in the obtained emulsion was 41:1QQ according to NMR. Table 1 shows the performance evaluation results of cement molded products using the obtained emulsion.

Comparative Example 1 After adding 100 parts of water, 3 parts of nonylphenol added with 20 moles of ethylene oxide, 0.5 parts of sodium dodenlebenzenesulfonate, and 1 part of acrylamide to a reactor, a mixed monomer of 69 parts of ethylene acrylate (EA) and 30 parts of MMA was added. Polymerization was carried out in the same manner as in Example 1 to obtain an acrylic emulsion (II) having a Tg of +5°C.

Next, emulsion copolymerization of ethylene and vinyl acetate was carried out in the same manner as in Example 1 in the presence of 100 parts of the above acrylic emulsion resin. Table 1 shows the performance evaluation results of cement colored products using the obtained emulsion.

Comparative Example 2 Example! In the presence of 100 parts of the resin content of the acrylic emulsion (1) obtained in step 1, 350 parts of a 0.5% hydroquine ethyl cellulose aqueous solution and 7 parts of nonylphenol added with 20 moles of ethylene oxide are added. Next, 25 parts of vinyl acetate was added, the temperature was raised to 50°C, and the ethylene pressure was increased to 50 kg/kg.
As'' pressure was applied to start polymerization using ammonium persulfate and Rongalit. Next, 203 parts of vinyl acetate was continuously added so that the concentration of vinyl acetate in the polymerization system was 2 to 3%, and polymerization was proceeded. The resulting emulsion had a ratio of ethylene-vinyl acetate copolymer to acrylic copolymer of 350:to.

Met. Table 1 shows the performance results of cement moldings similar to those in Example 1 using this emulsion.

Comparative Example 3 100 parts of a 0.5% hydroxyethyl cellulose aqueous solution and 2 parts of nonylphenol added with 20 moles of ethylene oxide were added to a pressure autoclave. Next, 10 parts of vinyl acetate was added, and the ethylene pressure was 50 kg/a at 50°C.
m'' and polymerization was started using ammonium persulfate and Rongalite. Next, 52 parts of vinyl acetate was continuously added so that the concentration of vinyl acetate in the polymerization system was 2 to 3%, and the polymerization was proceeded. An ethylene-vinyl acetate copolymer emulsion (EVA emulsion (I)) was obtained.The ethylene content of the emulsion was 38% by weight according to NMR.
Ta.

Next, the acrylic emulsion (1) obtained in Example 1
and the EVA emulsion (1) at a resin content of 100:2.
The mixture was blended at a ratio of 5:5, and the performance of cement molded products similar to that in Example 1 was evaluated using this mixture.

The results are shown in Table 1.

Comparative Example 4 82 parts of water and 20 parts of ethylene oxide in a pressure autoclave
Molar addition of 3 parts of nonylphenylniter and 1 part of sodium dodecylbenzenesulfonate and 3 parts of acrylamide
part was dissolved. Next, 25 parts of vinyl acetate and 58 parts of 2-ethylhexyl acrylate were added, the temperature was raised to 50°C, the ethylene pressure was increased to 50 kHz/an'', and polymerization was started using potassium persulfate and Rongalite. After 5 hours. By removing ethylene, an emulsion with a solid content concentration of 55% was obtained.The composition analysis by NMR is as follows.

Acrylamide 2.6%, ethylene 16.0%, vinyl acetate 24.0%, 2-ethylhexyl acrylate 57
．． 4%.

Using this emulsion, the performance of the cement composition was evaluated in the same manner as in Example I.

As is clear from Table 1, Examples 1 to 3 of the present invention have no cement hardening delay and the cement molded products have excellent physical properties, but Comparative Examples 1 to 4, which deviate from the present invention, have a large hardening delay. It can be seen that the physical properties are unbalanced.

Claims (1)

[Claims] (1) The glass transition temperature obtained by emulsion polymerization of an acrylic ester monomer having an alkyl group having 1 to 18 carbon atoms and/or a methacrylic ester monomer having an alkyl group having 1 to 18 carbon atoms is 0. It is obtained by emulsion copolymerizing ethylene and saturated carboxylic acid vinyl ester in the presence of an acrylic emulsion at a temperature of 20 to 300 parts by weight based on 100 parts by weight of the acrylic resin component. 1. A cement composition comprising 35 to 200 parts by weight of an emulsion as resin solids based on 100 parts by weight of cement.