JPS59184754A - Cement admixture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cement admixture, and more particularly to a cement admixture made of modified polyvinyl alcohol (hereinafter polyvinyl alcohol will be abbreviated as PVA) having a silyl group in the molecule.

Conventionally, methods of mixing water-soluble polymers such as polymer emulsions, latex, PVA, and methylcellulone into cement have been widely used for the purpose of improving the mechanical properties of cement, and these methods have been shown to have certain effects. Are known. However, even with these methods, the bending strength or Table 1117
The current situation is that little improvement can be expected in terms of preventing the formation of a laitance layer that weakens the strength.

In view of the above-mentioned current situation, the present inventors conducted intensive research with the aim of improving various properties of cement, and as a result, by mixing modified PVA with a silyl group in the molecule into cement (mortar or concrete), the UE It has excellent mechanical strength such as rice strength and abrasion resistance (surface strength), and
The present invention was completed based on the discovery that it is possible to provide a cement composition that dramatically improves adhesive strength to adherends.

The present invention will be explained in more detail below.

The modified PVA containing a silyl group in the molecule used in the present invention may be any type as long as it contains silicon in the molecule, but the silyl group contained in the molecule may be an alkoxyl group or an acyloxyl group. Particularly preferably used are those having a reactive substituent such as a sifnol group or a salt thereof, which is a hydrolyzate thereof.

Methods for producing such modified PVA include a method in which a silyl group is introduced into OPVA or a modified polyvinyl acetate containing a carboxyl group or a hydroxyl group by post-modification using a blocking agent; A method for saponifying a copolymer with an olefinically unsaturated monomer, ■ Polymerization of a vinyl ester in the presence of a mercaptan having a silyl group at the terminal obtained by and A method of saponifying polyvinyl ester) V is mentioned. In the method of post-modifying PVA6 or modified polyvinyl acetate using a silylating agent, for example, the silylating agent is added to an organic solvent that does not react with the silylating agent, such as benzene, toluene, xylene, hexane, heptane, ether, or acetone. Powdered PVA or the above modified polyvinyl acetate is suspended in the solution with stirring, and the silylating agent and PV A or the above modified polyvinyl acetate are mixed at a temperature ranging from room temperature to the boiling point of the silyl stopper. ) A silyl group-containing modified PVA can be obtained by reacting V or further saponifying vinyl acetate units using an alkali catalyst or the like. As inhibitors used in post-denaturation, organohalogensilanes such as trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, vinyltrichlorosilane, diphenyldichlorosilane, and triethyl/L/7/L/orsilane are used. , organosilicon esters such as trimethylacetoxysilane and dimethyldiacetoxysilane, organoalkoxysilanes such as trimethylmethoxysilane and dimethyldimethoxysilane,
Examples include organosilanols such as trimethylsifnol and diethylsilanedio-p, aminoalkylsilanes such as N-aminoethylaminoprobyltrimethoxysilane, and organosilicon isocyanates such as trimethylsilicon isocyanate. The rate of introduction of the silylating agent, that is, the degree of modification, can be arbitrarily adjusted by adjusting the amount of the silylating agent used and the reaction time. Also obtained is I))
The degree of polymerization and degree of saponification of modified PVA containing groups are determined by the P used.
The degree of polymerization and saponification of VA or the degree of polymerization and saponification reaction of the above-mentioned modified polyvinyl acetate can be adjusted as desired.

Or vinyl esters and silyl groups containing olefinic unsaturation? In the method of saponifying a copolymer with a tomer, for example, a vinyl ester is copolymerized in an alcohol using a Fuji force initiator, and then an alcohol solution of the copolymer is added with an alkali. Alternatively, a silyl group-containing modified PVA can be obtained by saponifying the copolymer by adding an acid catalyst. Vinyl esters used in the above method include vinyl acetate, vinyl propionate, vinyl formate, etc., but vinyl acetate is preferred from an economic standpoint. Examples of the olefinically unsaturated monomer containing a silica group used in the above method include vinylsilanes represented by the following formula (1) and (meth)acrylamidoalkylsilanes represented by the following formula (1).

w' CH3=CH-(CH2)n-Si-(2)5-m
(1) [Here, n is 0 to 4, m is 0 to 2, R'
is an alkyl group having 1 to 5 carbon atoms.
Chill, Echillfxt), It
2 is a flukoxyl group or acyloxyl group having 1 to 40 carbon atoms (the alkoxyl group or acyloxyl group may have an oxygen-containing substituent), W is a hydrogen atom or a methyl group, and R4 is a hydrogen atom Ushita has carbon number 1-5
The alkyl group, approximately 5, represents an alkylene group having 1 to 5 carbon atoms or a divalent organic residue group in which chain carbon atoms are bonded to each other through oxygen or nitrogen, respectively. Note that when two R1s exist in the same monomer, R1s may be the same or different. Furthermore, when two or more R2s exist in the same monomer, R2s may be the same or different. ] expression (+
) Specific examples of vinylsilanes include vinyltrimethoxysilane, vinyltriptoxysilane,
Vinyltrinu(β-methoxyethoxy)silane, vinyltriacetoxysilane, allyltrimethoxysilane,
Allyltrimethoxysilane, Vinylmethyldimethoxysilane, Vinyldimethylmethoxysilane Atoxysilane, Vinyldimethylmethoxysilane, Vinylmethyldiacetoxysilane, Vinyldimethylmethoxysilane, Vinylisobutyldimethoxysilane, Vinyltriisoproboxysilane, Vinyltriptoxysilane ,
Vinyltrihexyloxysilane, Vinylmethoxydihexyloxysilane, Vinyldimethoxyoctyloxysilane, Vinylmethoxydioctyloxysilane, Vinyltrioctyloxysilane, Vinylmethoxydifuryloxysilane, Vinyldimethoxylauryloxysilane, Vinylmethoxydiolay Roxysifun, vinyldimethoxyoleyloxysilane, and general formula %) (where 11, m is the same as above, and X represents 1 to 20)
Examples include polyethylene glycolized vinyl sulfur represented by: Further, specific examples of the (meth)acrylamidoalkylsifune represented by formula (II) include 6-(meth)acrylamidopropyltrimethoxysifune, 6-(meth)acrylamidopropyltriethoxysifune, 6-(meth)acrylamido-propyltri(β-methoxyethoxy)silane, 2-(meth)acrylamido-2-methylpropyltrimethoxysilane, 2-(meth)acrylamido-2-methylethyltritoxysilane, N- (2-(meth)acrylamidoethyl/I/)-aminopropyltrimethoxysilane, 3
-(meth)acrylamide-10 pyltriacetoxysilane, 2-(meth)acrylamide-ethyltrimethoxysilane, 1-(meth)acrylamide-methyltrimethoxysilane, 3-(meth)acrylamide-propylmethyldimethoxysilane, 5 -(meth)acrylamide-propyldimethylmethoxysilane, s-(N-methyl-(meth)acrylamide)-propy)Vtrimethoxysilane, 3-((meth)acrylamide-methoxy)-
6-hydroxypropyltrimethoxysilane, 3-1
meth)acrylic 7midomethoxy)-propyltrimethoxysilane, dimethyl-6-(meth)acrylamide-
Propi zv - 3 - (Trime
Toxicity Lilly) − Bropira
Examples include ammonium chloride, dimethyl-2-(meth)acrylamido-2-methylpropy)v-3-(trimethoxysilyl)propy)Ly ammonium chloride, and the like.

Also, the modified PVA used in the present invention. f
, When copolymerizing the vinyl ester with the silicon-containing olefinic unsaturated monomer, in addition to the above two components, unsaturated monomers copolymerizable with such monomers, such as styrene, 7 /L'Kyl vinyl ether, vinyl versatate, (meth)acrylamide, olefins such as ethylene, propylene, α-hexene, α-octene, (meth)acrylic acid, crotonic acid, (
anhydride) unsaturated acids such as maleic acid, fumaric acid, and iconic acid, and their alkyl esters and alkali salts, sulfonic acid-containing monomers such as 2-acrylamido-2-methylpropanesulfonic acid, and their alkalis. 4. j, trimethy/v-2-(1-(meth)acrylamide-1.

1-dimethyl chloride≠) ammonium chloride, trimethyl-3-(1-(meth)arylamide 10-py) V) ammonium chloride, 1-vinyl-2-methylimidazole and its 4
It is also possible to have a cationic monomer such as a graded monomer present in a small proportion.

In addition, in the method of saponifying a polyvinyl ester (VF) having a silyl group at the terminal obtained by polymerizing a vinyl ester in the presence of a mercaptan having a silyl group, for example, one step is to polymerize a vinyl ester using a radical initiator. , a mercaptan having a silyl group is added to the polymerization system all at once, in parts, or continuously to make the mercaptan having a silyl group present in the polymerization system, and by chain transfer to the mercaptan, a polyvinyl ester having a silyl group at the end is produced. After the polyvinyl ester is produced, a modified PVA having a silyl group can be obtained by saponifying the polyvinyl ester by adding an alkaline solution of the polyvinyl ester or an acid catalyst.

As the mercaptan having a silyl group used in this method, 3-()rimethoxysilyl)-propyl mercaptan and the like can be used. In producing modified PVA by this method, it is also possible to include a small proportion of an unsaturated monomer copolymerizable with the vinyl ester used in method (2).

In the above-mentioned three production methods of the modified PVA containing a silyl group in the molecule used in the present invention, a copolymer of a vinyl ester and an olefinically unsaturated monomer containing a silyl group is used. Method of saponification and vinyl ester in the presence of mercaptan having silyl group) L/
A method of saponifying polyvinyl ester/V having a silyl group at the end obtained by f-polymerization is preferably used in terms of ease of industrial production and homogeneity of the resulting modified PVA.

Modified PV containing silyl group used in the present invention
The content of silyl groups in A, the degree of cyanization, or the degree of polymerization are appropriately selected depending on the purpose and are not particularly limited. silyl group is effective even in a relatively small content, and usually 0.01 to 10 mo) V% as a monomer center containing a silyl group,
Preferably, it is selected from the range of 0.1 to 2.5 moles.

The saponification degree is usually preferably in the range of 70 to 100 mo/V%. Further, the degree of polymerization is usually selected from the range of 10 to 3,000.

The method of dissolving the above-mentioned modified PV and A used in the present invention in water is usually carried out by dispersing the modified PVA into water, adding an alkali such as sodium hydroxide in some cases, and heating the modified PVA with stirring. An aqueous solution can be obtained.

The cement admixture of the present invention is used by mixing it with cement and, if necessary, fine aggregate or aggregate (eg, sand, gravel, etc.).

In the present invention, the amount of modified PTA added is preferably 0.01 to 30% by weight, particularly 0.05 to 10% by weight, based on the cement. If the amount is less than 0.01 weight, the effect is essentially the same as not adding it, and if the amount exceeds 30 weight, the fluidity of the cement tends to deteriorate, and adding such a large amount There is no need to have children. As for the addition method, it is most convenient to use a fine powder of modified PVA having a silyl group in the molecule from the viewpoint of workability, but a method of adding an aqueous solution can also be used.

Although the modified PVA of the present invention exhibits a high effect even when used alone, it is also possible to use it in combination with an admixture such as a polymer emulsion or latex, PVA, modified PVA, or a cellulose derivative. Depending on the purpose, good results can be obtained by using them together.

The cement admixture of the present invention has excellent bending, compressive strength, and abrasion resistance (
It is characterized by providing a cement composition with excellent mechanical strength such as surface strength) and high adhesive strength to adherends. Although the reason why the admixture of the present invention has the above-mentioned remarkable performance is not fully elucidated, the silyl group in the modified PVA, which has a silyl group in the molecule, is based on calcium silicate, which is a component of cement. It has high reactivity with compounds or bone phase, and it strongly binds the cement crystal particles and aggregate, and the water retention properties of modified PVA suppress the migration of free water from the cement to the surface. The remarkable performance described above is achieved by suppressing the formation of a weak layer (laitance layer) whose main component is calcium hydroxide on the cement surface due to the reaction between calcium hydroxide, which is abundant in PVA, and the silyl group in modified PVA. It is estimated that this will be achieved.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

In addition, in the examples, unless otherwise specified, the keys "%" and "
"Part" represents the weight standard.

Example 1, Comparative Example 1.2 A copolymer of vinyl trimethoxysilane and vinyl acetate was saponified to contain 0.2 mol% of silyl group as a vinyl sulfate unit, and the degree of saponification of the vinyl acetate unit was 98. 5mo)
A modified PVA having a silyl group in the molecule with a polymerization degree of 2000 was obtained. 0.5 part of this modified PVA fine powder was added to 100 parts of Portland cement and 300 parts of Toyoura standard sand, and 65 parts of water was added and kneaded so that the mortar flow value was 170.
The material was molded in accordance with the Physical Test Method for Cement, and the strength was measured after curing for 4 weeks under standard conditions (20° C., 165% RH). In addition, the sample was immersed in water to determine whether calcium hydroxide was leached from the cement. Furthermore, after 20 minutes of mixing the mortar, a pre-manufactured mortar board (cement-
The sand was cured for 4 weeks at a ratio of 1:2, and then coated to a thickness of 3 mm on a 40x40 sheet (40x40), and immediately attached to a slate board. After curing under standard conditions for 4 weeks, the adhesive strength was measured using a measuring jig with an autobluff at a tensile speed of 1 m+/min. The measurement results are shown in Table 1.

For comparison, examples are given for the case where the modified PVA in Example 1 is not used (Comparative Example 1) or the case where unmodified PTA (saponification degree 20 mol%, polymerization degree j800) is used (Comparative Example 2) The results of measurements conducted in the same manner as in 1 are also shown in Table 1.

In the composition of the present invention (Example 1) using modified PVA having a silyl group in the molecule, compared with each comparative example,
It can be seen that the strength and adhesion of the adhesive are extremely excellent, and the elution of K and calcium hydroxide is extremely small.

Table 1 1) According to JIS-R5201.

2) When 100 parts of cement was immersed in 100 parts of tap water with p■6.5 for one week, the higher the PE[, Pfl of the water, the greater the elution.

Examples 2 to 4 The same procedure as in Example 1 was carried out except that modified PVA as shown below was used instead of the modified PVA used in Example 1. The results are shown in Table 2. It can be seen that both have high strength and adhesive strength.

'ff7m Example 2: Contains 0.3 mol% of silyl groups obtained by saponifying a copolymer of vinyl triacetoxycycne and vinyl acetate as vinyl siphon units, and the degree of saponification of vinyl acetate units is 99.0 mol %, modified PVA with a degree of polymerization of 2000 Example 3 Nidimethi/l/-2-acrylamide-2-methylpropyl-3-1-IJ methoxy
Contains 0.2 mol% of silyl groups obtained by saponifying a copolymer of bropylammonium chloride and vinyl acetate as acrylamide units, and the degree of cyanization of vinyl acetate units is 93 mo) V%, Modified PVA with a polymerization degree of 1750.

In fact, Example 4: 3-) 2 silyl group units obtained by saponifying a modified polyvinyl acetate having a silyl group at the end obtained by polymerizing vinyl acetate 71/i in the presence of 10-pyramethoxysilyl mercaptan. A 10% aqueous solution of modified PVA containing 990% by mole of saponification of vinyl acetate units and a degree of polymerization of 50.

Table 2

Claims (5)

[Claims] (1) A cement admixture made of modified polyvinyl alcohol having a group in the molecule. (2) A patent claim that is a saponified product of a co-T1 polymer with an olefinically unsaturated monomer having a silyl group in the molecule of modified polyvinylalco-/L/cabinyl nysterto having a silyl group in the molecule. The cement admixture according to item 1. (3) Olefinic atoms having a silyl group in the molecule
3. The cement admixture according to claim 2, wherein the monomer is vinylalpoxysilane. (4) The cement admixture according to claim 2, wherein the olefinically unsaturated monomer having a silyl group in the molecule is (meth)acrylamidoalkylalkoxysilane. (5) The modified polyvinyl alcohol having a silyl group in the molecule is a saponified product of a polyvinyl ester having a silyl group at the end obtained by polymerizing a vinyl ester in the presence of a mercaptan having a silyl group. Cement admixture according to item 1.