JPS61174497A - Production of multilayered structural sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing a multilayer sheet consisting of a film layer and a fibrous layer.

Prior Art It is known in the art to produce paper-formable pulp-like particles called "fibrids" from synthetic high molecular weight polymers.
For example, the Tokuko Sho 35-t18514 can be used as the newsletter
Publication No. 57321 describes fibrids obtained by mixing a polymer solution with a precipitant in the solution in the presence of shearing force.

Additionally, Tokai Publication No. 59-603 describes that fibers, tapes, films, and other molded products with molecular orientation formed from an optically anisotropic solution are mechanically beaten to form fibrids. In addition, polyacryloni ditrile,
Fibrids, which are made by beating short fibers such as polyester to give paper-making properties, are also mentioned.

It is also known that these fibrids can be mixed with other fibers and particles as needed to be made into paper-like sheets, and it is also known that after papermaking, they can be heated and pressed using a calendar (hot press). It is being

Paper-like sheets obtained from such fibrids are generally porous and have uneven surfaces. This is advantageous as a composite material because 6C1, for example, a composite resin, etc. can easily penetrate into it, and it has the advantage of good adhesion even when a shell resin is applied to the surface.

However, on the other hand, this property also becomes a drawback when used as a material for electrical insulators.

That is, being a porous material means the presence of pores and an air phase, and therefore, when used alone, dielectric breakdown is likely to occur from the pores. Furthermore, unevenness on one surface may impair slipperiness, leading to difficulty in handling during use.

In order to solve these problems, a composite sheet called "laminated paper" in which a film and a paper-like sheet are laminated together has been considered. This composite sheet is made by laminating a film made of the same or different kinds of polymers to paper. For example, it is made by laminating a film made of the same polymer to a synthetic paper of poly(metaphenyleneiso7talamide). is described in Tokkai No. 58-177350. These "laminated papers" do not necessarily need to be made of synthetic paper, but may be paper made of wood pulp or linter pulp, or nonwoven fabric that can be called dry synthetic paper.

Regardless of the method used, bonding a film and a paper-like sheet or non-woven fabric requires steps such as manufacturing the film, manufacturing the paper-like sheet or non-woven fabric, and adhering the two, so the manufacturing cost per unit area is low. It is unavoidable that the amount of damage will become extremely large, and there is also a risk that peeling will occur at the adhesive interface during use.

On the other hand, it is also known that a polymer solution is applied to the surface of a paper-like sheet or nonwoven fabric to form a thin layer of polymer on the surface layer, and this has the advantage of low manufacturing cost. However, it is difficult to apply uniformly, a uniform film may be formed on the surface of a paper-like sheet such as a laminated paper or a non-woven fabric, and the resin is absorbed all over the surface.

Therefore, although so-called laminated paper has great technical significance in the field of synthetic paper, etc., the above-mentioned problems are the main impediments to its adoption and development.

OBJECTS OF THE INVENTION The main object of the present invention is to provide an economical and efficient method for producing a multilayer structure sheet that has a structure substantially similar to the laminated paper described above and does not cause the problem of peeling between layers. I have a lot to offer.

Another object of the present invention is to provide a method for economically and efficiently manufacturing a multilayer sheet particularly suitable as an electrically insulating material.

Structure of the Invention The above-mentioned object is to provide a sheet (A) consisting essentially of synthetic fibrids to another fibrous sheet (B) according to the invention.
) and heated and pressurized to form the fibrid sheet (
This is achieved by fusing and integrating A) with the fibrous sheet CB) and forming the fibrid sheet layer in the laminate into a film.

The term "synthetic fibrids" used in the present invention generally refers to thin leaf-like pieces or short fibers made of thermoplastic synthetic polymers and having a large number of fibrils.

As such synthetic fibrids, Japanese Patent Publication No. 35-118
Not only those formed by the wet method (precipitation method) K as described in Bulletin No. 51, etc., but also those formed by mechanical beating of molded products having molecular orientation as described in Japanese Patent Publication No. 59-603. Alternatively, it may be made by beating short fibers such as polyacrynitrile or polyester to give paper-making properties.

Among such synthetic fibrids, those described in Japanese Patent Publication No. 35-11851 and Japanese Patent Publication No. 59-603 are preferably used in the method of the present invention. This is because these synthetic fibrids have a larger specific surface area than general short fibers with paper-making properties, and are easier to fuse and weld. Especially the Special Public Interest Publication (Sho 35-11)
The wet method described in No. 851 is more preferable. This is because the fibrids produced by the wet method described in Japanese Patent Publication No. 35-11851 are often in the form of very thin film pieces, and therefore the sheet after papermaking is a laminate of these. This is because it is easy to perform such operations.

Note that the synthetic fibrids formed by the wet method may contain a small amount of inorganic additives (for example, mica particles) and a solvent, if necessary.

The thermoplastic polymers that make up the synthetic fibrids include:
Aromatic polyamides with excellent heat resistance are preferred, especially
Copolyamides containing poly(metaphenylene isophthalamide) or metaphenylene isophthalamide as the main constituent are preferred, but other polymers such as poly(metaphenylene isophthalamide) or metaphenylene isophthalamide are preferred.
Polyesters such as ethylene terephthalate), poly(ethylene 2.6 naphthalate), Nine 6. nylon 6
It may also be aliphatic polyamide such as No. 6, polyimide, polyamideimide, or the like.

In the present invention, the sheet (A) consisting essentially of synthetic fibrids is produced by mixing the synthetic fibrids alone or with a small amount of fibers or fibrous materials and forming the sheet by a conventional method. The fibers or fibrous material to be mixed with the synthetic fibrids may be made of the same kind of polymer as the polymer constituting the synthetic fibrids, or may be made of a different kind of polymer. Also, wood pulp,
Linter pulp or the like may also be used. In any case, the content of such fibers or fibrous materials should be less than 10% by weight.
, is preferably substantially free.

On the other hand, for the fibrous sheet, synthetic fibrids and short fibers are mixed in a ratio of 10/90 to 90/lO (preferably 30/70 to 10/1O).
A paper-like sheet made by mixing the paper at a ratio of 70/30) is preferable, but it may also be paper made from ordinary wood pulp or linter pulp, or a nonwoven fabric produced by a dry or wet method using short fibers or continuous long fibers.

When the sheet (B) is made by mixing synthetic fibrids and short 111M, the nuclear synthetic fibrids may be of the same type or different type from the synthetic fibrids constituting the sheet (A), but it is not possible to carry out industrially. In some cases, it is more economical to use similar products. On the other hand, the short fibers to be mixed with the synthetic fibrids may be made of the same type of polymer as the fibrids forming the five-sided sheets (A) and (B).
Generally, it is preferable that the fiber has a softening temperature not lower than that of the synthetic fibrids of the sheet (A), and generally, aromatic polyamide fiber, polyamideimide fiber, polyimide fiber, polybenzimidazole fiber with excellent heat resistance is used. etc. are suitable.

Examples of specific combinations of such synthetic fibrids and short fibers include the following combinations.

(&) All synthetic fibrids and short fibers are made of poly(metaphenylene inphthalamide).

That is, poly(metaphenylene isophthalamide) is made into the fibrids described in Japanese Patent Publication No. 35-11851, and at the same time, they are spun wet or dry, heat treated in both cases, and cut to make short fibers, and a slurry of only synthetic fibrids and short fibers are made. A wet gauze sheet (referred to as Bl) is prepared from a slurry containing both synthetic fibrids and synthetic fibrids.

(b) The sheet containing only synthetic fibrids (A) is composed of fibrids of polyethylene phthalate terephthalate, which is a copolymer of isophthalic acid and terephthalic acid, and the fibrous sheet (B) is composed of beaten fibers of tt rHIJ ethylene terephthalate. Groove.

(C) A synthetic 71'brid only sheet (A) is made from popal fibrids, and a fibrous sheet (B)
is formed using the beaten product of linter bulge.

In the present invention, instead of laminating the two sheets (8) as described above, it is also possible to manufacture them separately and overlap them after drying, but in the case of industrial implementation, they are overlapped at the time of making the wet paper. It is preferable to match. For example, a method is preferably employed in which two paper-making KNL vats are used, one is filled with a slurry of only synthetic fibrids, the other is filled with both synthetic fibrids and short fibers, and the two are drawn and stacked.

These wet paper sheets are then dried. Although there are no restrictions on the type of dryer, a continuous drum type dryer is preferred in practice.

The sufficiently dried laminated wet paper is then heated and pressed using a heated press or a pair of heated rollers.

Synthetic fibrid sheet (4) and fibrous sheet a3)
When laminating the sheets and subjecting them to heat and pressure treatment, it is preferable to heat the sheet (4) at a high temperature from the side.The heating temperature should be higher than the softening temperature of the synthetic fibrids constituting the sheet (A). By pressure treatment, the synthetic fibrids of the sheet are fused &) 1w melted to form a film, and the sheet (4) and sheet 03) are fused to form an integrated sheet. It is necessary to select the conditions for leaving the room depending on the type of bride, etc.

In the multilayer sheet obtained by 5K, the synthetic fibrid sheet (4) is formed into a film, with a smooth surface on that side (surface layer), and a smooth surface on the side of the fibrous foot (B) (base layer). The material part) becomes a rough surface similar to that of ordinary paper by simply being compressed by ◆, and many voids remain in this layer.

FIG. 1 is a micrograph (approximately 300 times) illustrating the cross section of the multilayer structure sheet according to the present invention, showing a part (surface layer part) in which one synthetic fibrid is formed into a film and has a smooth surface and a dense structure. , inside* like regular paper! 2!
The synthetic fibrids and fibers are intertwined and welded at the interface between the two, and the surface layer and the base material are separated by an adhesive. It is observed that they are integrated even though they are not. That is, in this multilayer structure sheet, the film surface layer portion and the fibrous base material portion are firmly bonded without an adhesive, and there is no risk of peeling during use.

Effects of the Invention According to the method of the present invention as described above, a multilayer structure sheet similar to so-called laminated paper can be efficiently manufactured at low cost by a manufacturing process substantially similar to that of thermo-press paper (calendar paper).

In particular, aromatic polyamides, polyimides, etc. are difficult to manufacture into films and are expensive, so when such polymers are used, they have particularly good cost performance compared to laminated paper.

Another remarkable feature of the multilayer structure sheet produced by the method of the present invention is the change in electrical insulating properties due to the formation of a fibrid layer into a film.

For example, in the case of a multilayer sheet made of fibrids and short fibers, with a part of the fibrids forming a layer containing only fibrids, and the remaining fibrids forming a layer containing a mixture of fibrids and fibers, a layer containing only fibrids may be used. The more layers of fibrids there are, the higher the edge breakdown voltage (B, D, V,) of the sheet.

From this, the layer containing only fibrids is heated and pressed by M31.
It can be seen that the fibers tend to become denser and form a film, and that in a layer where fibers and fibrids coexist, the fibers inhibit the densification and film-like formation. In other words, fibrids are good at transmitting the force and heat necessary for densification, whereas fibers are poor.

The layer containing only fibrids has a high density, and in the layer containing fibers, the fibers are bonded by the fibrids, but spaces remain, so it is thought that the multilayer structure as described above is formed.

For example, in the multilayer sheet made of poly(metaphenylene isophthalamide) fibrids and short fibers, the density of the fibrid film layer is 1.2 to 1.
3, and the density of the separately formed film is 1.35
However, the density of the fibrous layer is 0.6~
It is 0.911 degrees, indicating a kana-like rough structure.

Such multilayer sheets are electrically insulating.

Because it is easy to handle, I! It is useful as an IIK electrical insulation material.

EXAMPLES Next, examples of the present invention will be described in detail. In the Examples, an example of a multilayer structure sheet using fibrids of aromatic polyamide and polyvinyl chloride is shown, but the present invention is not limited thereto.

Example 1 5 mol parts of terephthalic acid chloride, 95 mol parts of isophthalic acid chloride, and 100 mol parts of metaphenylenediamine were used as a solvent for tetrahydro 7-rano (Japanese Patent Publication No. 47-108)
Separate layers, wash with water, and dry the polymer polymerized at °C according to the method of No. 63! ! , dissolved in N-methylpyrrolidone, 12
．． A 5% solution was prepared. The intrinsic viscosity of the polymer was 1.3.

- A 30% aqueous solution of N-methyl biaridone was used as a precipitant.

The number of revolutions per rotation of the structure combining a stator and an airfoil turbine as shown in 4I 11H52-15621 is 1000.
A polymer solution and a precipitant were fed into a continuous precipitation device with a diameter of 0% and a diameter of 150 mm in a ratio of part by volume of the solution film to 30 parts by volume of a precipitant to obtain fibrids whose main repeating unit was metaphenylene isophthalamide. Ta.

The obtained fibrids were measured according to the method shown in JIS-P-8212K, and the sieving results were as follows.

150 mesh passage 6.3%8ON15
0 mesh 3 7.8 %48~80 mesh
16.9124-48 mesh 37
．． 2 Fa24 mesh not passing 32.8%
Substantially 33 pieces extracted from this fibrid-only layer
After extruding a wet paper of Ii/- and a solution of the same polymer dissolved in N-methylpyrrolidone into an aqueous solution of calcium chloride, heat-treated short fibers of 2d. Wet papers of 7 7 Elld, which were mixed at a ratio of :30 (weight ratio) and made into paper, were stacked and dried, and this laminate was hot pressed at 290° C. and 200) C9/a1 for 2 minutes.

In this way, a multilayer structure sheet having a thickness of 130 μm was obtained in which one side (the layer containing only fibrids) was smooth and formed into a film. The physical properties of this sheet are strength 7, 6 kII/
j *Elongation was 19.8%, and dielectric breakdown voltage was 4.2 kV.

For comparison, the fibrids and short fibers were mixed in a ratio of 60:4.
Dry the paper made by mixing at a ratio of 0 and dry it at 290°C.
The dielectric breakdown voltage of the sheet pressed for 2 minutes at 200 kJ/cit was only 2.8 k''/.

Practical Example 2 The dried mixed sand paper of short wL feed and fibrids obtained in Example 1 was layered with a wet paper made from a layer containing only fibrids obtained in Example 1 and dried. This laminate is 29
The physical properties of the multilayer sheet obtained by hot pressing at 0°C and 200 kf/ffl for 2 minutes are as follows: strength 7, 4 klP/-m
The elongation was 18.9 inches and the dielectric breakdown voltage was 4.1 kV.

Example 3 Commercially available poly(metaphenylene isophthalamide) fiber fa
(Registered trademark "Cornetex J") (2d.) 5 long fins;
Fibrids produced using the same polymer as the fiber constituting the fibers and using the apparatus used in Example 1 were prepared.

The fibrids were beaten to give Schopper Darashi Water Recycle 62@SR, which was fed to a cylinder paper machine having two vats, and half of it was put into one vat. The remaining fibrids and the short fibers were mixed and placed in the other vat. Wet paper sheets made from both vats using a cylinder paper machine were combined and passed through a short screen at 10°C, and the paper was made at a rate of 10m/min, thoroughly dried using a continuous dryer, and then wound up.

This anchor paper is 4001QF/CIE
*Continuously hot pressed using a roller press at 270°C.

The obtained sheet had only one side formed into a film and was smooth, had a strength of 7.8 g/-s, an elongation of 18.4 inches, and a dielectric breakdown voltage of 37 kV/m.

Example 4 Poly(metaphenyleneiso7talamide) was dissolved in N-methylpyrrolidone to form a solution, spun using an aqueous calcium chloride solution as a coagulation bath, and stretched in water to obtain a 2-denier fiber.

This was crimped and cut into a length of 51 m. This is used as sewage drawn fiber.

On the other hand, a 2-denier, 51-meter-long crimped fiber made of a commercially available aromatic polyamide fiber (trade name: Hoonex J) was used as the heat-treated fiber in both cases.

Submerged drawn fiber6. The fibers were mixed at a ratio of 40% and were passed through a card to form a web. A 3% N-methylbiridone aqueous solution was sprayed onto this web and immediately heated to 300°C e 4o.
It was pressed with an oky/ca calender roll to form a nonwoven fabric. The basis weight of this nonwoven fabric was 459/ze.

Next, a dilute slurry of fibrids produced in the same manner as in Example 1 was prepared, and the slurry was formed onto the nonwoven fabric. The basis weight for fibrids was 45I/ze. The obtained paper product was dried and hot-pressed at 290° C. and 5100° C. to obtain a multilayer structure sheet with a film-like surface on the negative side. The physical properties of this sheet were a strength of 4.8 kg/ls, an elongation of 6.6 cm, and a dielectric breakdown voltage of 3.1 kV.

Practical Fusuma Example 5 3-denier long fibers of commercially available vinyl chloride fibers (trademark: "Deviron") were obtained and cut into 5 lengths. This is called a fibrid.

Fibrids were made on a commercially available paper (manufactured by Toyo Ichishi Co., Ltd./%5) to prepare a laminated sheet having a fibrid portion of 3311/d. After drying this sheet, 90℃ 20
A sheet with a smooth negative surface was obtained by pressing at 0 mu/sf.

[Brief explanation of drawings]

FIG. 1 is a photomicrograph illustrating a cross section of a multilayer structure sheet manufactured according to the present invention. The sheet shown in FIG. 1 was manufactured using a sheet made from synthetic fibrids (A) and a fibrous sheet made from a mixture of synthetic fibrids and short fibers (B).

Claims (4)

[Claims] (1) Sheet (A) consisting essentially of synthetic fibrids
is laminated with another fibrous sheet (B) and heated and pressurized to fuse and integrate the sheet (A) with the fibrous sheet (B) and separate the layers of the sheet (A) in the laminate. A method for producing a multilayer structure sheet characterized by forming it into a film. (2) The fibrous sheet (B) is a sheet made by mixing synthetic fibrids and short fibers.
1) A method for producing a multilayer structure sheet as described in section 1). (3) The method for manufacturing a multilayer structure sheet according to claim (2), wherein both the sheet (A) and the fiber sheet (B) are formed by a wet process, and both are laminated as wet paper sheets. (4) The method for producing a multilayer structure sheet according to claim (1), wherein the fibrous sheet (B) is a nonwoven fabric produced by a dry process.