JPS5919059B2 - Joint cement for plasterboard - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to joint cement for gypsum board.

Conventionally, joint cement used for treating the joints of gypsum boards is mainly made of gypsum, with water-soluble organic polymeric substances such as polyvinyl alcohol and methyl cellulose as adhesives, and asbestos powder as an anti-sagging agent. It is known that a small amount is added.

This joint cement has advantages such as good workability, no sagging during construction, and good adhesion with joint tape. However, because it contains asbestos powder, it can cause lung cancer and cancer. There are health problems such as mesothelioma, and there is a demand for the development of joint cement that does not use asbestos powder.

The present invention aims to provide a joint cement that meets such requirements, and includes 100 parts of gypsum and 3 to 3 parts of cement.
8 parts, 90-110% of oxalic acid and/or malic acid based on the cement, and 0.3-110% of a water-soluble organic polymeric substance.
This is a joint cement for gypsum board consisting of 1.5 parts.

The gypsum used in the present invention is a gypsum that uses hydraulic properties, and usually hemihydrate gypsum is used.

The cement used is usually early-strength, super-early-strength, medium-heat, white Portland cement, or mixed cement containing silica powder, fly ash, blast furnace slag, etc., and the ratio of this to 100 parts of gypsum is 3 to 8. Department.

If the amount is less than 3 parts, the anti-sagging effect will be low, and if the amount is more than 8 parts, the anti-sagging effect will be excellent, but the adhesion of the joint tape will be poor, the color tone will change after the coating dries, and the finishing process will be particularly difficult. Adversely affects the color tone of paint finishes, etc.

Oxalic acid and/or malic acid are necessary to adjust the strong alkalinity caused by using cement as an anti-sag agent to a pH of 8 to neutral to prevent the occurrence of stains, etc., and the ratio of this to cement is 90-90%. 110% is appropriate.

According to the inventor's experiments, even though they are the same organic acids, citric acid, tartaric acid, gluconic acid, and succinic acid significantly thicken joint cement slurry, reduce workability, and accelerate hardening. It was found that this method was not suitable due to reasons such as low pH adjustment effect.

As the water-soluble organic polymer substance used as the adhesive, known water-soluble organic polymer substances having adhesive properties such as polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, alginic acid, etc. are used, but cold water soluble ones are preferable. .

For example, the product name "Denka Poval B-17SJ" (manufactured by Denki Kagaku Kogyo ■) is a fine powder of 48 mesh or less and is partially saponified, so it has excellent adhesive properties.

The ratio of this to 100 parts of plaster is 0.3 to 1.5 parts, and if the amount is less than 0.3 parts, the adhesive strength to the plasterboard and the adhesiveness of the joint tape will deteriorate;
If the amount exceeds 5 parts, workability will deteriorate significantly.

The joint cement of the present invention has the effect of eliminating health problems associated with the conventional use of asbestos powder without impairing performance such as workability, adhesion, and prevention of sagging.

The present invention will be explained below with reference to Examples, in which parts described in the specification are expressed on a weight basis.

Example Joint cement was prepared by combining gypsum hemihydrate, Denka Poval B-178, ordinary Portland cement, and oxalic acid in various proportions, and the mixture was mixed well with water and then jointed with gypsum board in advance. The tape was embedded in the tape using a spatula and evaluated for workability, water retention, sagging, adhesion, and color tone.

The results are shown in Table 1. Experiments/161-3 are examples of the present invention.

As a reference example, a case using conventional asbestos threshold powder is also shown.

The performance evaluation was performed based on the following criteria.

Workability ◎; No stickiness and good embedding △: Slightly poor workability ×; Workability is markedly poor Water retention ◎; Water retention is good △; Water retention is somewhat poor and drying is rather fast ×; Water retention is not good and drying is very fast Poor workability Sagging prevention effect ◎; Good with no sagging △; Some creases occur ×; Adhesion of joint tape with a lot of sagging ◎; Good adhesion △; Adhesive strength is somewhat weak ×; No adhesive force at all and peels off. Similar measurements were made using malic acid instead of oxalic acid, and the results were almost the same.

Claims (1)

[Claims] 1 100 parts by weight of gypsum, 3 to 8 parts by weight of cement, and 90 to 110 parts of oxalic acid and/or malic acid to the cement.
% by weight, and 0.3 to 1.5 parts by weight of a water-soluble organic polymer substance.