JPS59155476A - Cement-based adhesive composition - Google Patents

Abstract

PURPOSE:To provide a cement-based adhesive consisting mainly of cement which contains hydroxyalkylalkylcellulose and having excellent adhesion properties and a long open time. CONSTITUTION:The adhesive composition consists mainly of (a) 100pts.wt. hydroxyalkylalkylcellulose having a degree of substitution of 1.2-1.5 and solubility in water or alkali. Component (a) includes Portland cement, alumina cement, and blast furnace cement. When component (b) has a degree of substitution lower than 1.2, no thickening effect can be obtained and when the degree exceeds 1.5, sufficiently long open time is unobtainable. Component (b) are hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cement adhesive composition suitable for bonding inorganic tiles, stones, secondary cement products, etc.

Generally, cement has good adhesion, but the adhesion of commonly used cement-water-based or cement-aggregate-water based cement mixtures depends on the ground conditions at the time of construction and the properties of the adherend. Especially when the adhesive material has a high water absorption property, dehydration from the adhesive layer can cause poor setting of the cement mixture and decrease in plasticity, making it difficult to obtain good adhesive strength. It has the disadvantage of

In order to eliminate the above-mentioned disadvantages, alkylcelluloses such as methylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, hydroxybutylmethylcellulose, hydroxyethylethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyalkylcellulose or hydroxyl are added to the cement mixture. Attempts have been made to add and blend water-soluble nonionic cellulose ethers such as alkyl alkyl cellulose. These nonionic cellulose ethers all have a high degree of etherification (degree of substitution, S) from the viewpoint of imparting water solubility.
is used in the range of 1.6 to 2.5.

Such water-soluble nonionic cellulose ethers are
It has a thickening effect of increasing the viscosity when dissolved in water, and also imparts excellent water retention and plasticity to the cement mixture.

However, when cement mixtures containing water-soluble nonionic cellulose ethers as described above are used to bond inorganic tiles, stones, or cement-based secondary products, they harden from the surface of the coating layer. , a phenomenon occurs as if only the surface portion is formed by a film (skinning phenomenon), and this phenomenon is particularly noticeable in conditions of high temperature and low humidity, and progresses rapidly over time. - The adhesive layer that has undergone the skinning phenomenon loses its plasticity, and the desired mechanical strength cannot be obtained after curing.
This phenomenon becomes more pronounced as the degree of polymerization of the nonionic cellulose ether increases and as the amount of nonionic cellulose ether added increases.

This is not a problem if the standing time (oven time) when applying heptamenyl hydrate containing nonionic cellulose ether and adhering it to the adherend is relatively short, but in general, In many cases, it is necessary to take a certain amount of oven time for the work, and in such cases, the mixture will harden while standing, making it difficult to obtain the desired adhesive strength. There is a problem in that no adhesion can be performed.

The present invention aims to provide a cement-based adhesive composition that solves the conventional problems as described above. Hydroxyalkylalkyl cellulose soluble in water or alkali of 0.02 to .5
The main ingredient is 2 parts by weight.

The present inventors have discovered that cement-based adhesives exhibit extremely good adhesion to inorganic tiles, stones, cement-based secondary products, etc., and can take the sufficient oven time required during construction work without any inconvenience. As a result of intensive research on agent compositions, as mentioned above, it has a degree of substitution within a specific range of 1.2 to 15,
The present invention was completed based on the discovery that it is extremely effective to use hydroxyalkylalkylcellulose which is soluble in water or alkali.

The composition of the present invention exhibits excellent adhesion to various substrates and has the remarkable effect of having a longer oven time (time until skinning phenomenon occurs) compared to conventional cement mixtures. There is.

The cement adhesive according to the present invention will be explained in detail below.

First, as the cement which is component (a) which is the main component in the present invention, various conventionally known cements can be used, and specific examples include Portland cement, alumina cement, and blast furnace cement.

Next, the hydroxyalkylalkylcellulose as the (oral) component used in the present invention is as described in (a) above.
It is used for the purpose of imparting water retention to the cement component, increasing the plasticity of the composition containing it, and providing oven time. It is required that the degree of substitution (degree of etherification) is 1.2 to 1.5 and that it is soluble in water or alkali.

This is because when this composition is mixed and kneaded with water, sand, etc. and used as a paste adhesive as described later, if the degree of substitution is less than 1.2, no thickening effect will be obtained; If the degree of substitution is greater than 1.5, the oven time will be sufficiently long.
This is due to the inability to do so.

Such components (b) include hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose,
Examples include hydroxybutyl methylcellulose and hydroxyethylethylcellulose. These are the degrees of substitution (
When the degree of etherification is close to 1.2, it is swellable in water and soluble in alkali (degree of etherification), and when the degree of etherification is close to 15, it is soluble in both water and alkali.

The amount of component (b) to be used is 0.0 parts by weight per 100 parts by weight of component (a) from the viewpoint of achieving the above-mentioned purpose.
The amount is in the range of 2 to 2 parts by weight, preferably 0.05 to 1 part by weight.

In order to apply this mixture of components (a) and (b) as an adhesive, it is necessary to mix and knead the mixture with an appropriate amount of water and sand, etc., and use it as a paste. In this case, as long as the purpose of the present invention is not impaired, in addition to the above-mentioned sand, natural aggregates such as jiyari, artificial aggregates, pigments, fillers, inorganic or organic fibrous substances, resin emulsions, powdered resins may be used. etc. may be added and blended.

Next, examples of the present invention will be given, and all parts indicated as "parts by weight" are shown.

Example 1 100 parts of ordinary Portland cement, 50 parts of No. 8 silica sand, 0.3 parts of hydroxypropyl methyl cellulose with a degree of etherification of 1.3 (2% aqueous solution of pH 12, viscosity 4000 centipoise at 20°C) and 50 parts of water. After uniformly kneading it, apply it on a concrete plate prepared in advance so that it has a thickness of 6 strokes, and then heat it to a temperature of 25 cm.
The coated surface was left in a constant temperature room at 60% relative humidity and checked for skinning over time by touching the coated surface with one's fingers, and the results shown in Table 1 below were obtained.

For comparison, hydroxypropyl methyl cellulose with a degree of etherification of 1.8 and a 2% aqueous solution of 2
A mixture having the same composition as above except that one having a viscosity of 4000 centipoise at 0° C. was used was similarly tested, and the results are also shown in Table 1 below.

〔Judgment criteria〕

A: Mortar adheres to fingertips, no skinning B: Mortar does not adhere to fingertips, but dents due to finger pressure, skinning occurs C: Surface layer hardens due to skinning Example 2 100 parts of ordinary Portland cement, 50 parts of No. 8 silica sand, etherified 0.5 part of hydroxypropyl methylcellulose (viscosity 15,000 centipoise in a 2% aqueous solution at pH 12) having a value as shown in Table 2 below and 50 parts of water are kneaded for 2 minutes using a mortar mixer,
Immediately apply the resulting mixer on a concrete plate to a thickness of 5 mm, then set the oven time to θ~60'' as shown in Table 2 below, and apply half of the mixture to the coated surface. Porcelain tiles (45 mm x 45 mm) were crimped.

This product was left indoors for four weeks, and the adhesive strength between the tile and concrete after being left was examined using a Kenken tensile tester, and the results shown in Table 2 below were obtained. (For reference, this result is shown in the attached drawing).

[Brief explanation of drawings]

The drawing shows the open time (minutes) and adhesive strength (
Kf/cI/l). Patent applicant Shin-Etsu Chemical Co., Ltd.

Claims (1)

[Claims] (a) 100 parts by weight of cement, and (b) degree of substitution 12
Cement-based adhesive composition comprising 0.02 to 2 parts by weight of water- or alkali-soluble hydroxyalkylalkylcellulose of ~15 as a main ingredient