JPS6149438B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a fibrous plate-like body. Conventionally, fibrous plates have been manufactured by bonding fibrous materials such as rock wool and glass wool with a starch binder. However, starch has high hygroscopicity, and the elastic modulus of starch in a hygroscopic state decreases, so that the fibrous plate-like material that has absorbed moisture is easily deformed. In order to solve this problem, the first method proposed is to use other binders instead of starch binders, or to use starch and other binders together. In this case, other binders include emulsions such as acrylic resins and vinyl acetate resins, melamine resins, epoxy resins, urea resins, and phenol resins. As a second method, a method has been proposed in which the other binder mentioned above is coated on the surface of a plate-shaped body using starch as a binder to prevent deformation due to moisture absorption. However, these methods have the following drawbacks. That is, (1) the moisture absorption deformation prevention effect may be small.
(2) Increasing the effect of preventing moisture absorption and deformation increases the cost. (3) The second method complicates the manufacturing process. Therefore, an object of the present invention is to provide a method for producing a fibrous plate-like body free of such drawbacks. The characteristics of this invention include a polyhydric alcohol with a molecular weight of 1000 or less selected from the group consisting of ethylene glycol, propylene glycol, butanediol, pentanediol, glycerin, pentaerythritol, polyethylene glycol, and polypropylene glycol, starch, and a fibrous material. and,
The present invention provides a method for producing a fibrous plate-like material, which comprises making a wet mat from a mixture with water and drying the wet mat. Next, this invention will be explained in detail. Examples of the fibrous material used in this invention include rock wool, glass wool, asbestos, and pulp. As the low molecular weight polyhydric alcohol, ethylene glycol, propylene glycol, butanediol, pentanediol, glycerin, pentaerythritol, polyethylene glycol, polypropylene glycol, etc. are used. Their molecular weight is preferably 1000 or less. Such things are
It is soluble in water, compatible with starch, and relatively inexpensive. During the production of fibrous plate-like bodies, it does not react with starch or fibrous materials, does not change its quality, and has the property of not easily volatilizing during production. The mixing amount of such polyhydric alcohol is suitably 3 to 60%, preferably 5 to 30%, based on the weight of starch. If it is less than 3%, the effect will be small, and if it is more than 60%, the properties as a binder under normal conditions, such as strength, will deteriorate, which is not desirable. The reason why the moisture resistance of the fibrous plates is improved by adding such a polyhydric alcohol to the starch binder is considered to be as follows. That is, fibrous plates are usually manufactured by making wet plates with a thickness of 5 to 20 mm from a mixture of the compound and water and drying them. During this time, it gelatinizes, dries, and solidifies. In the drying process, at the beginning, moisture is uniformly reduced from the entire board during constant rate drying, but when the process moves to lapse rate drying, the areas near the surface of the board lose moisture faster than the central area. As a result, the plate surface tends to contract and is subjected to tensile stress. As the drying progresses further, tensile stress acts inside the board, and after the entire board is dried and solidified, distortion remains in the board. When such a plate-shaped body is placed in a high-humidity atmosphere, it absorbs moisture, and if its own weight or stress is applied at that time, the plate deforms greatly due to unbalance of residual strain. Therefore, if the residual strain that occurs during drying is made less likely to occur, these defects will disappear. Polyhydric alcohol is
It is thought that due to its water-retaining properties, water is lost at the same rate from the board surface and inside during lapse rate drying, thereby preventing residual strain from occurring.
Therefore, deformation of the plate due to moisture absorption is prevented. Next, examples will be described. Example 1 100 parts of rock wool (based on weight, the same applies hereinafter), 8 parts of starch, 0.2 parts of paraffin wax, 3 parts of asbestos, 63 parts of ethylene glycol (20% of starch (based on weight) in the obtained plate-shaped body) , hereinafter the same)) and stir to create a slurry with a concentration of 3.0%. Pass this through a sieve box with a 20 mesh wire mesh bottom, and then
Matsuto is made by squeezing with a pressure of 0.5Kg/ ^cm2 . This pine tree contains 45% water. When this mat was dried in a hot air dryer at 150°C, a fibrous board with a specific gravity of 0.40 and a thickness of 12 mm was obtained. Comparative example Example 1 except that ethylene glycol was not added
A fibrous board was obtained in the same manner as above. Samples for moisture absorption deformation test (width 100 mm, length 700 mm,
(thickness: 10 mm) and sample for elastic modulus measurement after moisture absorption (width:
A piece (30 mm long, 100 mm long, 10 mm thick) was cut out and subjected to moisture absorption deformation tests and elastic modulus measurements after moisture absorption. In the moisture absorption deformation test, a sample was placed on a fulcrum with a distance of 600 mm between the fulcrums, and after deforming under its own weight due to moisture absorption (24 hours), the distance of decline in the center portion was measured. The atmosphere at this time was set at a temperature of 30°C and a relative humidity of 90%. The elastic modulus was measured by leaving the sample under these conditions for 24 hours, and then determining the bending elastic modulus. The measurement results showed that the amount of deformation due to moisture absorption was 1.5 mm in Example 1 and 16 mm in Comparative Example.
Flexural modulus is 300Kg/cm ² in Example 1 and 340 in Comparative Example
It was Kg/ ^cm2 . That is, although there is no difference in the bending elastic modulus between the two, the amount of deformation due to moisture absorption is significantly smaller in Example 1. Examples 2 to 8 Fibrous boards were prepared in the same manner as in Example 1, except that the type and amount of polyhydric alcohol added were changed as shown in the following table, and the results of the moisture absorption deformation test are shown in the same table.

【table】

[Table] As described above, according to the manufacturing method of the present invention,
A fibrous plate-like body that is less deformed due to moisture absorption can be easily manufactured without increasing costs.

Claims (1)

[Scope of Claims] 1. A polyhydric alcohol with a molecular weight of 1000 or less selected from the group consisting of ethylene glycol, propylene glycol, butanediol, pentanediol, glycerin, pentaerythritol, polyethylene glycol, and polypropylene glycol, starch, and fibrous material. 1. A method for producing a fibrous plate-like material, which comprises making a wet mat from a mixture of a material and water, and drying the wet mat. 2. Claim 1, wherein the polyhydric alcohol is mixed in an amount of 3 to 60% by weight with respect to the starch.
A method for producing a fibrous plate-like body as described in .