JPS6013986B2 - cement products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cement product containing a fibrous material of cellulose ether.

Conventionally, asbestos has been widely used in the manufacture of cement products for the purpose of improving properties such as impact resistance and bending strength of the products. However, in recent years, diseases such as silicosis and lung cancer have been frequently observed among workers in industries that use asbestos, so the use of asbestos is now restricted or prohibited by law. For this reason, fibers such as alkali-resistant glass, nylon, and polyester vinylon are used as substitutes for asbestos.
Many alternatives, such as pulp and mica, have been proposed, but these alternatives have many drawbacks, and no substance has been found that can completely replace asbestos. For example, glass fibers have good initial strength when uniformly dispersed, but have poor weather resistance and are difficult to disperse uniformly, and synthetic fibers such as polyester fibers are evenly dispersed with inorganic substances such as cement. It is difficult to do so.

Furthermore, when using these methods to manufacture cement products, the retention of inorganic substances becomes a problem, causing problems such as the grains being sorted at the bottom and the carp grains at the top, making it difficult to obtain a uniform product. Yes,. Methods of using pulp, paper, water-soluble resin, etc. are being explored as a way to correct these defects, but pulp and paper have a solid content of 1% by weight based on the solid content.
If the above amount is not added, the effect will not be sufficient, and on the other hand, there is a problem that adding this large amount makes it difficult to maintain the product as nonflammable. Therefore, there was a strong desire to develop a new asbestos substitute. As a result of intensive research in view of such technical problems, the present inventors have discovered that cellulose ether fibers with a low degree of substitution exhibit excellent performance as an asbestos substitute, and have completed the present invention.

That is, the present invention provides a cement containing 0.2 to 1 part by weight of cellulose ether fibrous material having an average substitution mole number of 0.05 to 1.2 per glucose residue per 10 parts by weight of solid content. It's about the product.

To explain this, the main effects brought about by using the above cellulose ether fiber in the present invention are {1
1) Reinforcing performance that can replace asbestos; 2) Improved water-concentrating properties due to improved retention of inorganic substances.

The reinforcing properties of '1' are not superior to those of polyester, vinylon, glass fiber, etc. when thoroughly mixed, but they do have excellent dispersibility and compatibility with inorganic substances. Therefore, it was confirmed that it exhibits excellent reinforcing properties in practice. Regarding the water passing properties of '2', when the amount of asbestos is reduced, the holding power of inorganic substances decreases, so the water resistance decreases, and the uniformity within the layer may also be impaired. For this reason, attempts have been made to use pulp, paper, mica, etc., but the effects are not sufficient. On the other hand, the cellulose ether has excellent ability to retain inorganic substances, resulting in improved water concentration. Examples of cellulose polymers used in the present invention include hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, and mixed ethers thereof, particularly hydroxypropyl cellulose and hydroxyethyl cellulose. methylcellulose,
Hydroxypropyl methylcellulose is preferred.
In order to achieve the above effects, it is important that these cellulose ethers have a degree of ether substitution (average number of substituted moles per glucose residue M.S.) in the range of 0.05 to 1.2. Ru. Below 0.0, the effect is similar to that of pulp, while above 1.2, it becomes water-soluble or alkaline water-soluble, and not only has a poor reinforcing effect, but also improves water resistance. Methylcellulose (
M. S. :2.5), hydroxyethyl cellulose (M
．． S. = 2.5), which is the same as using a water-repellent resin such as polyvinyl alcohol. For the reasons mentioned above, cellulose ether M. S. The range is set to be 0.05 to 1.2, but the optimum range varies somewhat depending on the type of cellulose ether.

For example, in methylcellulose, 0.1<M. S. <1.2
and 0.05 M. for hydroxyethyl cellulose. S.
<0.5 is the most desirable range, generally 0.1<
M. S. <1.0 is a more preferable range. In addition, when attaching importance to water properties, those with a relatively high degree of substitution,
When reinforcing properties are important, it is desirable to have a relatively low degree of substitution. Regarding the fiber length, fiber lengths of 0.5 to 40 ribs are preferably used, but when reinforcing properties are important,
It is preferable to use a relatively long one, about 0.5 skin to 1 centimeter, or a shorter one, from 0.5 skin to 1 centimeter, if moisture retention is important.

The amount of cellulose ether used is preferably 0.2 to 1 part by weight per 10 parts by weight of solid content when obtaining a cement product, and if the amount is less than 0.2 parts by weight, the above-mentioned effects cannot be obtained. If the amount exceeds 1 part by weight, not only will the reinforcing effect not be increased, but the nonflammability will be impaired.

The more desirable addition amount varies depending on the required reinforcing properties and water leakage properties, but if it is reinforced with other fibers, it is best to use a shorter amount of 0.2 to 5 parts by weight. When used in combination with pulp etc., even 0.2 to 2 parts by weight exhibits an effect. When both reinforcing properties and water permeability are required, it is desirable to use 2 to 1 part by weight. Thus, the solid content in the present invention refers to cement mixed with asbestos, pulp, glass fiber, synthetic fibers such as nylon, vinylon, polyester, mica, sand, etc. as appropriate. Among these, the pulp may be wood pulp or linter pulp, but when reinforcing properties are important, lithotar pulp is more desirable. Next, specific examples will be given.

Cement, asbestos, vinylon fiber, pulp, cellulose ether, and water as shown in the example table were mixed in a mixing tank, sucked in a cylinder, drawn with felt, compressed and dehydrated in a press, and then steam-cured and room-temperature curing. A plate-shaped body with a thickness of 5 legs was made by performing the steps in order.

The bending strength, intralayer separation, and retention rate after 4 weeks were examined, and the results were as shown in the table.

Intralayer separation: Judgment was made in the following four stages.

A: Each component plays completely uniformly. B: Each component is almost uniformly wet. C: The playability of each component is slightly uneven. D: The mixing condition of each component is uneven. Retention rate: Cellulose ether HPC: Hydroxypropyl cellulose MC: Methyl cereulose in the product conversion rate table for solid content in circulating slurry

Claims (1)

[Claims] 1. Average number of moles substituted per glucose residue is 0.05 to
1.2 fibrous material of cellulose ether with a solid content of 1
A cement product containing 0.2 to 10 parts by weight per 00 parts by weight. 2. A cement product according to claim 1, wherein the cellulose ether is selected from hydroxypropylcellulose, hydroxyethylmethylcellulose or hydroxypropylmethylcellulose. 3 The cellulose ether fibrous material has a fiber length of 0.5
The cement product according to claim 1, which has a diameter of mm to 40 mm.