JP2000080570A - Glass fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a glass fiber enabling the prevention of the occurrence of coagulation and the formation of not-dispersed chopped strands during a wet type sheet forming process, and suitable for producing a nonwoven fabric of a low density by imparting a binder containing a stearic acid ester of a polyethylene glycol of a specific average molecular weight to a glass fiber. SOLUTION: A binder containing 0.05-2.0 wt.% of a stearic acid ester of a polyethylene glycol having a weight average molecular weight of >=2500 is imparted to a glass fiber in such a manner that the ignition loss becomes in the range of 0.01-0.4 wt.%, subsequently the fiber is converted to chopped strands, and they are subjected to a wet-type sheet forming process to obtain the objective glass fiber nonwoven fabric.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass fiber, and more particularly, to a glass fiber suitable for producing a glass fiber nonwoven fabric by a wet papermaking method after cutting into a predetermined length.

[0002]

2. Description of the Related Art Glass fibers are obtained by drawing molten glass into fibers from a number of nozzles provided at the bottom of a platinum bushing and immediately applying a sizing agent using an applicator called an applicator. It is manufactured by collecting and winding a number of the books.

Further, the glass fiber nonwoven fabric is produced by cutting the above glass fiber bundle into a predetermined length to form a glass chopped strand, and then by a dry papermaking method or a wet papermaking method.

In the wet papermaking method, glass chopped strands are dispersed in an aqueous dispersion and papermaking is performed. In order to obtain a glass fiber nonwoven fabric having a uniform thickness by this method, glass chopped strands must be formed during papermaking. , Glass monofilament (monofilament) in aqueous dispersion
It is necessary to disperse evenly in a state close to. When glass fibers are mixed with organic fibers such as pulp and polyester fibers, it is particularly necessary that the glass chopped strands be uniformly dispersed and uniformly mixed with substances other than glass fibers.

[0005] In order to satisfy the above properties, as a sizing agent for this type of glass fiber, water-soluble polymers such as starch, acrylamide-vinyl acetate copolymer, carboxymethylcellulose, polyvinyl alcohol and polyethylene oxide are used. A sizing agent comprising a cationic surfactant such as a cationic fatty acid amide and various nonionic surfactants is used.

[0006]

Conventionally, glass fiber non-woven fabrics have been used for various purposes, but are often used as a base material for composite materials, and are generally made of vinyl chloride resin, epoxy resin, unsaturated polyester resin and the like. To form a composite material.

Therefore, glass fiber nonwoven fabrics are required to have excellent impregnating properties with various resins, and one factor that determines the impregnation efficiency is the density of the nonwoven fabrics.
That is, the lower the density of the nonwoven fabric, the more easily the resin is impregnated. Conversely, the higher the density of the nonwoven fabric, the less the resin is impregnated.

That is, in order to increase the resin impregnating property of the glass fiber nonwoven fabric, it is desirable to reduce the density as much as possible, but it is very difficult to adjust the density of the glass fiber nonwoven fabric in the papermaking process.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a glass fiber which has good dispersibility during wet papermaking and can obtain a glass fiber nonwoven fabric having a low density. Is what you do.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted various experiments to achieve the above object. As a result, the present inventors have found that by suppressing slippage between glass fibers during wet papermaking, dispersed glass fibers can be obtained. When is formed as a nonwoven fabric, the frictional force between the glass fibers causes each glass fiber to be sparsely deposited, so that the density of the glass fiber nonwoven fabric can be reduced, and the dispersion of glass chopped strands during papermaking can be achieved. A glass fiber having good properties was found, and the present invention was proposed.

That is, the glass fiber of the present invention is characterized by being coated with a sizing agent containing a stearic acid ester of polyethylene glycol having a weight average molecular weight of 2500 or more.

In the glass fiber according to the present invention, the sizing agent may comprise a stearic acid ester of polyethylene glycol having a weight average molecular weight of 2,500 or more in terms of solid content of 0.05 to 2.0.
0% by weight, and the ignition loss is 0.01 to 0.4.
% By weight.

Further, the glass fiber of the present invention is characterized in that it is used for a glass fiber nonwoven fabric.

[0014]

The stearic acid ester of polyethylene glycol having a weight average molecular weight of 2500 or more contained in the sizing agent of the present invention suppresses slippage by increasing the friction between glass fibers during wet papermaking and improves the quality of glass fibers. Has the effect of preventing aggregation of glass filaments and generation of undispersed chopped strands during wet papermaking.

However, the weight average molecular weight is 25
If it is less than 00, the effect of stabilizing the dispersion of the glass fibers becomes poor, and the glass fibers once dispersed in a filament form during wet papermaking easily aggregate. Further, even when the content of the stearic acid ester is less than 0.05% by weight, the glass filaments are still aggregated, so that good dispersion stability cannot be maintained. The dispersion speed is extremely low, and undispersed chopped strands are easily generated, which is not preferable.

The weight average molecular weight used in the present invention is 2
As the stearic acid ester of polyethylene glycol of 500 or more, either a monoester or a diester can be used.

The adhesion rate of the sizing agent to the glass fiber of the present invention is suitably from 0.01 to 0.4% by weight in terms of ignition loss. That is, if the adhesion ratio is less than 0.01% by weight, the glass filaments are likely to aggregate, and a good dispersion state cannot be maintained. On the other hand, if it exceeds 0.4% by weight, the dispersion speed of the glass chopped strand becomes slow. At the same time, contamination of the aqueous dispersion during papermaking is caused.

The sizing agent used in the present invention is a sizing agent for various water-soluble polymers, cationic surfactants, nonionic surfactants, etc., in addition to the stearic acid ester of polyethylene glycol having a weight average molecular weight of 2500 or more. It is produced by appropriately containing the agent components.

[0019]

The glass fiber of the present invention will be described in detail below with reference to examples and comparative examples.

Example 1 First, the weight average molecular weight was 250
A sizing agent comprising 0.5% by weight of polyethylene glycol distearate of 0.5%, 0.5% by weight of polyethylene oxide having a weight average molecular weight of 300,000, 0.2% by weight of cationic fatty acid amide, and residual water was prepared.

This sizing agent is applied to E glass long fiber having a diameter of 10 μm so that the ignition loss is adjusted to 0.05% by weight, and 2,000 of these are bundled to form a strand, which is then wound. It was then dried and cut to a length of 13 mm to obtain a glass chopped strand.

Example 2 The procedure of Example 1 was repeated, except that the polyethylene glycol distearate having a weight average molecular weight of 2500 was changed to a polyethylene glycol monostearate having a weight average molecular weight of 6000.
Glass chopped strands were produced under the same conditions as in Example 1.

Example 3 The same sizing agent as in Example 1 was applied to E-glass long fibers having a diameter of 10 μm and the ignition loss was reduced to 0.
After adjusting to 3% by weight and applying, a glass chopped strand was produced under the same conditions as in Example 1.

Comparative Example 1 A polyethylene glycol distearate having a weight average molecular weight of 2500 was replaced with a polyethylene glycol monostearate having a weight average molecular weight of 1000 in Example 1.
Glass chopped strands were produced under the same conditions as in Example 1.

Comparative Example 2 A glass chopped strand was prepared under the same conditions as in Example 1 except that the sizing agent of Example 1 was omitted from the sizing agent of polyethylene glycol distearate having a weight average molecular weight of 2500. Was prepared.

Comparative Example 3 As a glass chopped strand, a glass chopped strand ECS13I-33G (manufactured by Nippon Electric Glass Co., Ltd.) prepared by applying a sizing agent containing no stearic acid ester of polyethylene glycol to glass fiber was prepared. .

Thereafter, the dispersibility of each of the above-mentioned glass chopped strands during wet papermaking was evaluated, and the glass chopped strands were weighed 150 g / m2.
The glass fiber nonwoven fabric of No. ² was prepared, and its thickness was measured.
Table 1 shows the results.

[0028]

[Table 1]

As is clear from Table 1, the glass chopped strands of Examples 1 to 3 all have good dispersion stability of glass fiber, a high dispersion speed, and the thickness of the glass fiber nonwoven fabric produced therefrom. Was also large and uniform.

Incidentally, the above-mentioned glass fiber nonwoven fabrics have a constant weighing. Therefore, as the thickness increases, the density decreases, and as the thickness decreases, the density increases. Therefore, the glass fiber nonwoven fabrics of Examples 1 to 3 all have low density.

On the other hand, the thickness of the nonwoven fabric made from the glass chopped strand of Comparative Example 1 was relatively large, but the dispersion stability of the glass chopped strand was poor. Further, the glass chopped strand of Comparative Example 2 was inferior in dispersion stability, and the thickness of the nonwoven fabric produced therefrom was small. Further, the glass chopped strand of Comparative Example 3 had good dispersion stability of glass fiber and a high dispersion speed, but the thickness of the nonwoven fabric produced therefrom was small.

The dispersion stability and the dispersion speed in the table are as follows. A predetermined amount of glass chopped strand is poured into an aqueous dispersion (white water), and the mixture is stirred for a predetermined time and immediately paper-formed. The dispersion stability was evaluated by visually observing the presence or absence of chopped strands.Dispersion stability was indicated by を when no agglomeration filament was generated, and indicated by X when a little was generated, and the dispersion speed was未 indicates that no undispersed chopped strands were generated.

Further, the thickness of the glass fiber nonwoven fabric was measured using a thickness gauge manufactured by Teklock Corporation.

[0034]

As described above, the glass fiber of the present invention has good dispersion stability during wet papermaking, has a high dispersion speed, and can be used to obtain a glass fiber nonwoven fabric having a low density. Becomes possible.

Claims (3)

[Claims] 1. A glass fiber characterized by being coated with a sizing agent containing a stearic acid ester of polyethylene glycol having a weight average molecular weight of 2500 or more. 2. The sizing agent contains 0.05 to 2.0% by weight of a polyethylene glycol stearic acid ester having a weight average molecular weight of 2,500 or more in terms of solid content, and has a loss on ignition of 0.01. 2. The glass fiber according to claim 1, wherein the glass fiber is adhered so as to be about 0.4% by weight. 3. The glass fiber according to claim 1, which is used for a glass fiber nonwoven fabric.