JPH02289197A - Production of fibrous sheet - Google Patents

Abstract

PURPOSE:To obtain a homogeneous fibrous sheet with a low basis weight from fiber which cannot be homogeneously dispersed and formed into paper layers by forming a film from a gelatinous mixture prepared by mixing a highly water absorbing resin with fiber and water onto a perforated conveyor, sucking and removing the excessive amount of the gelatinous resin and drying the resultant sheet. CONSTITUTION:A highly water absorbing resin (e.g. starch or graft copolymer of an acrylate) in an amount of 0.5-2wt.% based on water is blended with fiber (e.g. glass fiber having preferably 3-50mm length and 0.1-20mum diameter) in an amount of preferably 0.5-5wt.% based on the water and the water and the resultant blend is then applied onto a perforated conveyor to form a film. A water shower is preferably sprinkled thereon to regulate fiber orientation and the excessive amount of the gelatinous resin is sucked and removed. The resultant sheet is subsequently dried to afford a fibrous sheet improved in reinforcement of surface strength, prevention of fiber scattering and heat resistance and suitable as filters, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a fibrous sheet using fibers that are difficult to uniformly disperse and form into paper layers using conventional papermaking methods. .

[Conventional technology]

Conventionally, wet papermaking has been widely used as a method for manufacturing sheet-like textile products.For example, when manufacturing paper, fibers are uniformly dispersed in water, strained through a net, and then paper is placed on the net. It is manufactured by forming layers and drying them.

This method requires that the fibers be uniformly dispersed in the water and that the fibers be uniformly arranged during the formation of the paper layer. However, when using hydrophobic fibers, fibers with a large aspect ratio, fibers with high specific gravity, mixed fibers with a large difference in specific gravity, etc., it is difficult to obtain a fibrous sheet by uniformly dispersing them in water or forming a paper layer with a low basis weight. It is difficult.

There are also methods for manufacturing sheet-like fiber products using dry nonwoven fabric manufacturing methods such as spunbond and melt-blown resin bond, but considering these manufacturing methods, it is difficult to obtain composite fibrous sheets made of fibers with different characteristics.

[Problem to be solved by the invention]

The present invention has been made based on the above-mentioned circumstances, and its purpose is to form a uniform paper layer using fibers that are difficult to disperse uniformly in water, which have been difficult to make using conventional papermaking methods. An object of the present invention is to provide a method for producing a uniform fibrous sheet with a low basis weight.

[Means to solve the problem]

As a result of extensive research in order to solve the above problems, the present inventors have found that by forming a coating film using a gel-like mixture obtained by mixing a super absorbent resin, fibers, and water, the above problems can be solved. The inventors have found that the object can be achieved, and have completed the present invention based on this knowledge.

That is, in the present invention, a coating film is formed on a sign conveyor using a gel mixture obtained by mixing a super absorbent resin, fibers, and water, and then an excess amount of gel resin is removed from the coating film by suction. The present invention provides a method for producing a fibrous sheet, which comprises drying the fibrous sheet.

The superabsorbent resin used in the present invention is particularly limited as long as it absorbs water 50 to 1000 times its own weight, and its viscosity can be freely controlled when mixed with fibers. Instead, various polymer compounds commercially available as super absorbent resins are used.

Specifically, starch-based products such as starch-acrylate graft copolymers, cellulose-based products such as cross-linked carboxymethyl cellulose, vinyl alcohol-acrylate copolymers, polyacrylonitrile hydrolysates, and cross-linked polyacrylates Synthetic polymers such as , modified polyvinyl alcohol, and incyanate resins are preferably used.

Among these, for example, the relationship between the water absorption capacity and viscosity of a super absorbent resin commercially available as Kl gel from Kuraray ■ is as follows.

Water (g) Kl gel Water absorption capacity Viscosity (g)
dPas looo 5 200
0.51000 10 100
17.51000 15 67
37.51000 21
By changing the amount of super absorbent resin added as above, the viscosity of the gel mixture can be freely controlled, resulting in uniform dispersion of fibers in the gel mixture and coating film of the gel mixture. can be easily formed.

The fibers used in the present invention preferably have a length of 3 to 3.
50ffII11 having a diameter of 0.1 to 20 μm is used.

The material of the fibers is not particularly limited, and may include fibers with high specific gravity such as glass fibers, mineral fibers such as ceramic fibers, and metallic fibers such as stainless steel fibers, which are difficult to form a uniform paper layer using conventional papermaking methods. Various types of fibers can be used, including hydrophobic fibers such as synthetic polymer fibers such as carbon fibers, polyethylene fibers, and polypropylene fibers, and fibers with large aspect ratios.

Furthermore, it is also possible to use fibers with different characteristics, which have conventionally been difficult to form, to produce a uniformly low-weight fibrous sheet.

The blending proportions of the super absorbent resin, fibers, and water are preferably such that the fibers are 0.5 to 5% by weight and the super absorbent resin is 0.5 to 2% by weight relative to water.

In addition, if necessary, the above mixture may include glass powder,
Fillers such as calcium carbonate, various polymer powders, etc. can be added.

In the present invention, by mixing the superabsorbent resin, fibers, and water, the superabsorbent resin absorbs water and a gel-like mixture with appropriate viscosity can be easily obtained. Even when using fibers that are difficult to disperse, it can be uniformly dispersed. The viscosity of this gel-like mixture can be freely adjusted with water, and it can be easily dehydrated, making it advantageous for drying.

Next, a coating film is formed using the gel-like mixture obtained in this way, but since the gel-like mixture has excellent spreadability, it can be easily coated using various coating methods such as a roll coater method and a doctor knife method. A coating film can be obtained. The thickness of this coating film is preferably 0.5 to 511 m1.

Next, as necessary, water is sprayed from a water shower onto the coating film obtained in the above step to adjust the viscosity of the gel-like mixture, and the arrangement of the fibers is randomly adjusted.

Next, an excess amount of gel-like resin is removed from this coating film using succidin, and this is then dried to obtain the desired fibrous sheet. The gel-like resin is removed, for example, by suction using a suction box.
The water-containing superabsorbent resin recovered at this time can be reused in the initial mixing step, and this reuse can reduce the amount of water used. At this time, if the superabsorbent resin is not completely recovered and left on the fibers, the superabsorbent resin will act as an adhesive, improving the strength of the fibrous sheet, and when the resulting fibrous sheet is treated with resin. In addition, the liquid resin, especially the water-soluble resin, becomes evenly attached.

The coating film from which the gel-like resin has been removed is then passed through a blower if necessary.
etc., then released from the conveyor and dried in a dryer. Drying is usually carried out at a temperature of 200 to 300°C to obtain a low weight fibrous sheet with uniformly dispersed fibers.

Note that if the above-mentioned saccidine is performed on a smooth perforated conveyor, a smooth fibrous sheet can be obtained, but if this is performed on a perforated conveyor with a specific uneven shape or a perforated conveyor with a curved surface, unevenness will be obtained. A fibrous sheet having a shape or curved surface is obtained. In this way, the fibrous sheet of the present invention is not only smooth, but also has an uneven shape.
This includes those with curved surfaces and those that are individually shaped into a spherical shape.

The fibrous sheet obtained by the present invention can be used as a reinforcing sheet for reinforcing the surface strength of glass fibers, as a skin material for heat-insulating and sound-absorbing materials, as a filter, etc., and requires reinforcement of surface strength, prevention of fiber scattering, and improved heat resistance. It is used alone or in combination with other materials for the following purposes.

[Examples] Hereinafter, the present invention will be described in detail based on Examples, but the present invention is not limited thereto.

Example 1 FIG. 1 is a schematic cross-sectional view showing an example of an apparatus for manufacturing a fibrous sheet of the present invention. The following operations were performed using this device.

Raw materials with a mixing ratio of 12 g of water, 16 g of chopped glass strands (diameter 5 μm, length 6 mm), and 10 g of isocyanate-based super absorbent resin (Kuraray ■, KI Gel) were mixed into a kneader.
A gel-like mixture was obtained by mixing for 20 to 30 minutes in Step 1. Next, this gel-like mixture was fed from a hopper 3 onto a porous belt conveyor 2, and was coated onto the conveyor using a roll coater 4 to form a mixture of 640 g and 10 f. After coating to form a coating film, water was sprayed on it using water shower 5 to adjust the viscosity and randomize the fiber arrangement.
Next, this was suctioned using the suction box 6 to remove the gel-like resin. Next, the coating film and the conveyor were released from the mold using Pro 7-7, dried at 250°C using dryer 8, and then wound up using winder 9.

The obtained fibrous sheet has a thickness of 100 μm and a weight of 10 g/r.
It was evenly distributed in the rl.

Example 2 In the blending ratio of Example 1, instead of 16 g of glass chopped strands as the fiber, Rustan (Asahi Kasei Corporation) was used.
A fibrous sheet was obtained in the same manner as in Example 1, except that 16 g of carbon fiber, made of carbon fiber, length 6 m) was used.

The obtained fibrous sheet had a thickness of 120 μm and a weight of 10 g/
It was uniformly dispersed in the rrf.

Example 3 In the blending ratio of Example 1, instead of 16 g of glass chopped strands as the fiber, Rustan (Asahi Kasei Corporation) was used.
Example 1 except that 8 g of carbon fiber, length 6 mm) and 8 g of the glass chopped strand used in Example 1 were used.
A fibrous sheet was obtained in the same manner as above.

The obtained fibrous material has a thickness of 110 μm and a rate of lOg/rr
r was uniformly distributed.

FIG. 2 is a schematic cross-sectional view showing an example of the device.

Explanation of symbols Kneader-λ Porous belt conveyor hopper 4. Roll coater water shower suction box blower dryer 9. @Screening machine [Effects of the invention] The present invention allows papermaking to be carried out uniformly by using fibers that are difficult to disperse uniformly in water and fibers that are difficult to form a uniform paper layer at a low weight. It has become possible to produce fibrous sheets with low basis weight.

Claims (1)

[Claims] 1. A coating film is formed on a porous conveyor using a gel mixture obtained by mixing a super absorbent resin, fibers, and water, and then an excess amount of gel resin is removed from the coating film. A method for producing a fibrous sheet, which comprises removing it by suction and then drying it. 2. Form a coating film on a porous conveyor using a gel-like mixture obtained by mixing a super absorbent resin, fibers, and water, then adjust the fiber arrangement of the coating film using a water shower, and then apply the coating. A method for producing a fibrous sheet, which comprises removing an excess amount of gel-like resin from a membrane by suction, and then drying it.