JP3267815B2 - Manufacturing method of laminated sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminated sheet comprising a synthetic paper layer and a polyester film layer obtained by wet -making m-aramid fibrids and m-aramid fibers. More specifically, the synthetic paper layer and the polyester film layer are solidified by laminating a synthetic paper layer and a polyester film layer obtained by wet -making m-aramid fibrid and m-aramid fiber and subjecting them to calendering under special conditions. And a method for producing a laminated sheet integrated with the sheet.

[0002]

2. Description of the Related Art Aramid paper is mainly used as an electrical insulating material or a thin-leaf structure material. Aramid paper is a so-called nonwoven fabric type consisting essentially of aramid fibers, and aramid fibrids or fibrillated fibers are wet-processed. And a synthetic paper type in which a reinforcing fiber and a reinforcing fiber are wet-processed. The latter synthetic paper type aramid paper is further classified into a paper having a large air permeability composed of aramid fibrids and reinforcing fibers, and a paper having a small air permeability composed essentially of only aramid fibrids.

Aramid paper having high air permeability is advantageous in that it is rich in impregnation with insulating oil, resin and the like and is convenient for compounding. On the other hand, aramid paper having low air permeability has the advantage that there are few insulation defects and the like. is there.

As an insulating paper having both advantages, a multi-layered structure paper obtained by heat-sealing the above two layers, that is, a layer obtained by wet-casting aramid fibrids and fibers and a layer obtained by wet-casting only aramid fibrids. Are laminated, and heated and pressed to melt a layer of only aramid fibrid to form a laminated sheet (Japanese Patent Application Laid-Open No.
174497). Further, there has been proposed a laminated sheet obtained by thermocompression-bonding synthetic paper obtained by wet-forming aramid fibrid and aramid fiber and an aramid film (JP-A-58-17735).
No. 0).

[0005] The aramid paper layer and the aramid film layer constituting such a laminated sheet can be fused relatively easily, but the aramid paper layer and the polyester film layer are difficult to fuse with each other. It is difficult to obtain a good laminated body without using. However, when an adhesive is used, there are problems that not only the cost is increased, but also that the subsequent resin impregnation and the like are difficult to be performed, and the types of resins that can be used are limited.

As a method for solving such a problem, recently, (1) a method in which aramid paper and a polyester film are heated and pressed under specific conditions (Japanese Patent Application No. 5-175311), and (2) a polyester in aramid paper. A method has been proposed in which the polyester film is melt-impregnated beforehand and a polyester film is fused to the impregnated surface side (Japanese Patent Application No. 6-94339).

[0007]

Although these recently proposed methods are considered to be useful methods for producing a laminated sheet of an aramid paper layer and a polyester film layer,
For industrial implementation, the method (1) of heat-sealing the aramid paper and the polyester film has problems in the adhesive strength of both layers and workability in production, and the method (2). Has a tendency for the molten resin to penetrate into the central part of the aramid paper and agglomerate during the melt impregnation of polyester,
It turned out that there was a problem that it was difficult to keep polyester uniformly on the surface layer of aramid paper.

The present invention further improves the previously proposed method for producing a sheet in which a synthetic paper layer obtained by wet-making aramid fibrid and fiber and a polyester film layer are laminated, and the surface layer of the synthetic paper layer is improved. It is an object of the present invention to provide a method for producing a laminated sheet in which a part of a polyester film layer is melt-impregnated and strongly fused to a synthetic paper layer with good productivity.

[0009]

According to the present invention, an object of the present invention is to provide a laminated sheet comprising a synthetic paper layer and a polyester film layer formed from m -aramid fibrids and m-aramid fibers. The synthetic paper layer and the polyester film layer are laminated and supplied to a calendering device.
Preheating the synthetic paper layer before subjected to calendering under the conditions that the temperature of the synthetic paper layer becomes a higher temperature than the temperature of the polyester film layer, achieved by the subsequent preparation of the laminated sheet, which comprises rapidly cooling Is done.

[0010] Here, "m-aramid" refers to poly-m-
Refers to phenylene isophthalamide or a copolymer or mixed polymer containing the same as a main component. Components and ratios that can be copolymerized or mixed with poly-m-phenylene isophthalamide are
It is not particularly limited as long as the properties as m-aramid are not impaired.
(0 mol% or less) copolymerized with terephthalic acid, p-phenylenediamine, hexamethylenediamine, cyclohexyldiamine, or the like can also be used. Note that this m-
Aramid may contain inorganic salts, additives, fillers and the like.

The term "fibrid" refers to a fiber-forming polymer such as m-aramid or polyester dissolved in an amide solvent or the like, and the solution is coagulated and precipitated in a precipitant such as water under a shearing force. It means pulp-like particles having papermaking properties obtained by the above-mentioned method. The structure, properties, production method and the like are described in detail in JP-B-35-11851 and JP-B-37-5732.

The m-aramid fiber to be mixed with m-aramid fibrids to form a paper is the same m-aramid fiber as fibrid.
Stretched fibers made from aramid is rather preferably, fiber維長is 1 to 1
Suitable is about 0 mm and the thickness (fineness) of the fiber is about 0.5 to 5 de. These fibers may be used alone or in combination of two or more.

The mixing ratio between the m-aramid fibrids and the m-aramid fibers is from 20/80 to 80/20 by weight.
Is preferred. If the amount of m-aramid fibrid is too large, the air permeability, that is, the resin impregnating property is impaired, and if the amount is too small, the basic properties as paper are impaired .

In the present invention, papermaking to synthetic paper by a known papermaking method from an aqueous slurry of a mixture of the above m- aramid fibrids and m- aramid textiles (hereinafter, may be referred to as "m- aramid paper" Is formed, and one or two or more polyester film layers are laminated at or after the synthetic paper is made.

As the polyester forming the polyester film layer, a polyethylene terephthalate film is usually used, but a polyester obtained by copolymerizing another dicarboxylic acid component such as isophthalic acid or a diol component other than ethylene glycol such as butylene glycol may be used. Also, polyethylene-2,6-naphthalate can be used. It is desirable that these polyesters have a glass transition point at least 50 ° C., preferably about 100 ° C. lower than that of m-aramid. If the glass transition points of polyester and m-aramid are close to each other, it is difficult to obtain a good polyester-impregnated state, and it is difficult to expect good adhesion to the synthetic paper layer.

The polyester film layer may be a stretched polyester film or an unstretched polyester film, or a layer obtained by heating and pressing a web of polyester fibrid and / or polyester fiber at a softening temperature or higher to form a dense film. In any case, the intrinsic viscosity of the polyester film layer measured at 35 ° C. in an o-chlorophenol solution at 0.6 ° C. or higher, particularly 0.7 to 1.0, is relatively high. It is preferable to be composed of polyester. 0.6 intrinsic viscosity
Since the smaller polyester has a lower melt viscosity, the polyester softened and melted by calendering described below penetrates to the central portion of the synthetic paper layer and is easily aggregated and scattered, so that the object of the present invention is hardly achieved.

On the other hand, the synthetic paper layer preferably has an air permeability measured by the Gurley method of 5 minutes / 100 ml to 1000 minutes / 100 ml. The value of the air permeability is 1000 minutes / 100
Those having a low air permeability exceeding 100 ml have less pores through which the molten polyester can penetrate, resulting in poor impregnation during calendering, and those having a high air permeability value of less than 5 minutes / 100 ml are the molten polyesters. Easily penetrates into the central part of the synthetic paper layer, agglomerates and becomes scattered.

Therefore, in the present invention, a polyester film made of a polyester having an intrinsic viscosity of 0.6 or more is used, and a synthetic paper having an air permeability of 5 minutes / 100 m
It is recommended to use 1-1000 min / 100 ml.

In the present invention, the synthetic paper layer and the polyester film layer are overlapped with each other and calendered to soften and melt the polyester, and a part thereof is impregnated into the surface layer of the synthetic paper layer in contact with the polyester film layer. Lamination and integration are performed by solidifying,
It is preferable that the calendering is performed under the condition that the temperature of the synthetic paper layer side is 250 ° C. or higher, the temperature of the polyester film layer side is 50 ° C. or lower, and the temperature is 50 ° C. or higher than the glass transition point of the polyester. In particular, the polyester film layer side is 50 degrees from the glass transition point of the polyester.
It is preferable that the temperature be higher than 10 ° C. and lower than the melting point by 10 ° C. or more.

In this way, in most cases, the melt viscosity of the polyester during calendering is 100%.
The melt-softened polyester does not penetrate to the central part of the synthetic paper layer, but partially penetrates only to the surface layer portion of the synthetic paper, and most of the polyester remains on the surface in the form of a film.

The calendering pressure is 50 linear pressures.
kg / cm or more, particularly preferably 100 to 500 kg / cm.

As described above, in the laminate of the synthetic paper layer / polyester film layer in which the interface between the synthetic paper layer and the polyester film layer is melt-bonded, unnecessary post-pressing is minimized and the laminated sheet is cooled immediately. It needs to be solidified. For this reason, it is preferable that the calendering device can remove the pressure immediately after the heating and pressurizing. Therefore, it is more appropriate to use a calender roll than a flat plate press.

The cooling conditions are slightly different depending on the viscosity of the polyester, the heating and pressurizing conditions, and the like. Generally, at least the polyester film layer side is cooled to a temperature below the glass transition point of the polyester within about 10 seconds after calendering. In this state, a part of the polyester constituting the polyester film layer is melted and permeated only near the interface of the synthetic paper layer and solidified, and most of the polyester remains on the surface as a film. Is formed.

In order to carry out the process industrially, after heating and pressurizing with a pair of calender rolls having different surface temperatures, a cooling roll is provided immediately downstream thereof so that at least the polyester side is brought into contact with the cooling roll. It is appropriate to cool under the following conditions. As the cooling roll, a roll in which cooling water is passed is preferable. Further, the synthetic paper supplied to the calendering device is preferably preheated, for example,
Synthetic paper is preheated and supplied by a roll at 250 to 340 ° C. In a calendering device, the surface temperature of the roll on the synthetic paper is 150 to 250 ° C and the roll on the polyester film side is not heated or 200 ° C or less. , The heating and pressurizing can be performed substantially under the above temperature conditions.

In the above description, the case of manufacturing a laminated sheet having a two-layer structure in which a polyester film layer is laminated and fused on one side of a synthetic paper layer has been described. The present invention is also applicable to the case of producing a multilayer laminated sheet in which two or more polyester film layers are sandwiched.

In the latter case, since the polyester film layer is heated via the synthetic paper layer, it is preferable to verify the relationship between the set temperature of each roll and the temperature of each layer by an experiment in advance.

Hereinafter, an example for specifically implementing the method of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example in which two layers of separately produced m-aramid paper and one layer of polyester film are formed into a laminated sheet by the method of the present invention.

In FIG. 1, two upper and lower m-aramid papers (1) and (2) are preheated rolls (11) and (12), respectively.
And a preheated m-aramid paper is fed between the preheated m-aramid papers so that an unheated polyester film (3) is sandwiched between the preheated m-aramid papers and a laminate of m-aramid paper / polyester film / m-aramid paper Is heated and pressed by a pair of calender rolls (13) and (14). At this time, by adjusting the temperature of the preheating rolls (11) and (12) and the temperature of the calender rolls (13) and (14),
The temperature of the polyester film heated and pressed through the m-aramid paper is set so as to satisfy the above-mentioned conditions. Usually, the temperature of the preheating rolls (11) and (12) is 250
To 340 ° C., and the temperatures of the calender rolls (13) and (14) are appropriately selected within the range of 150 to 250 ° C.

The laminate, which is heated and pressurized by the calender rolls (13) and (14) and the respective layers are fused to each other, immediately comes into contact with the cooling rolls (15) and (16), and the temperature at which the polyester does not flow, that is, the glass transition point of the polyester. Cool down to the following temperature. The cooling rolls (15) and (16) are maintained at a temperature as low as possible by circulating cooling water at normal temperature (5 to 40 ° C). Then, after cooling, the resulting m-aramid paper layer / polyester film layer / m-aramid paper layer is wound up as a laminated sheet (4) integrally bonded.

FIG. 2 shows an example of manufacturing a laminated sheet in which a polyester film layer is fused to one side of an m-aramid paper layer. In this example, the m-aramid paper (6) is preheated to a predetermined temperature by a preheating roll (17), and an unheated polyester film (7) is supplied along one side of the preheated m-aramid paper. And the resulting m-
The laminate of aramid paper / polyester film is heated and pressed by a pair of calender rolls (18) and (19) having different temperatures. The calender roll has a high-temperature roll (18) on the m-aramid paper side and a low-temperature roll (19) on the polyester film side. Also in this case, the temperature of each roll is adjusted so that the temperature of the polyester film at the time of heating and pressing satisfies the above-described conditions. Usually, the temperature of the preheating roll (17) is 250 to 340 ° C.,
The temperature of 8) is 150 to 250 ° C, and the low-temperature roll (19) is not heated or is kept at a temperature of 200 ° C or less. Subsequent to the calendering, at least the polyester side is cooled to a temperature lower than the fluidization temperature of the polyester by a cooling roll (20) through which cooling water at normal temperature (5 to 40 ° C.) is passed. By this cooling, the surface layer of the m-aramid paper layer is uniformly impregnated with polyester and fixed, and wound up as a laminated sheet (8) in which the m-aramid paper layer / polyester film layer of the product is integrally bonded. .

FIGS. 3 and 4 show a so-called laminating method, which is a multi-layered paper (laminated paper) comprising an m-aramid paper layer and a polyester film layer as an intermediate material in the method of the present invention.
FIG. 5 shows an example in which the m-aramid paper layer / polyester film layer is tightly closed by laminating and laminating the respective polyester layers with each other, and applying heat and pressure. An example of manufacturing a fused laminated sheet will be described.

FIG. 3 shows an example in which a two-layer laminated paper is produced by a paper machine having two sets of circular papermaking sections. In the first circular papermaking section (21), m is supplied as indicated by an arrow A. -A synthetic paper layer is formed from an aqueous slurry (22) of aramid fibrid and m-aramid fiber, and is then formed into the following circular mesh papermaking section (2).
Aqueous slurry of polyester fibrid or polyester fiber alone supplied as indicated by arrow B in 3) (24)
, And a polyester layer is formed, and is laminated as it is in a wet paper state, and the laminate (25) is sent to a drying step (not shown) to form a two-layer laminated paper.

FIG. 4 shows an example in which two-layer laminated paper is manufactured by a fourdrinier paper machine provided with two sets of head boxes.
An aqueous slurry of m -aramid fibrid and m-aramid fiber is prepared from the head box (26), and an aqueous slurry of polyester fibrid or polyester fiber alone is formed on the second slurry from the second head box (27). The obtained laminate (28) is sent to a drying step (not shown) and dried to form a two-layer laminated paper. The slurry is supplied to the head boxes (26) and (27) as indicated by arrows.

FIG. 5 shows an example of the object of the present invention in which two-layer laminated paper (dry paper) obtained by laminating by the method shown in FIGS. An example of manufacturing a laminated sheet in which respective layers described below are integrally bonded is shown. In FIG. 5, two-layer laminated paper (3
1) The temperature of the m-aramid paper layer side (31a) is 250
The pre-heating roll (32) is preheated to 340 ° C., and the m-aramid side roll (34) is heated to a high temperature (150 to 250 ° C.) without preheating the polyester film layer side (31b). ) Without heating or at 200 ° C
A pair of calender rolls (33) (3) at the following temperatures
After heating and pressurizing in 4), the mixture is rapidly cooled by cooling rolls (35) and (36) through which cooling water at normal temperature is passed, so that the m-aramid paper layer and the polyester film layer are in the m-aramid paper layer surface portion. It is wound up as a laminated sheet (37) joined together by melt-impregnated polyester.

FIGS. 6 and 7 show an example of producing a three-layer laminated paper of m-aramid paper layer / polyester film layer / m-aramid paper layer by lamination.

FIG. 6 shows an example of producing a three-layer laminated paper by a paper machine in which three circular net papermaking sections are combined. In the first circular net papermaking section (41), m-aramid fibrids and m -aramid fibrils are produced.
A synthetic paper layer is formed from the aqueous slurry with the mid fiber (42), and a polyester layer is formed thereon from the aqueous slurry of polyester fibrid or polyester fiber only (44) in the second circular web forming section (43). And a synthetic paper layer is formed thereon from an aqueous slurry (46) of m -aramid fibrids and m-aramid fibers in a third circular web making section (45), and is laminated as wet paper as it is. The obtained three-layer laminated paper (47) is sent to a drying step (not shown) and dried to be a three-layer laminated paper. Also in FIG. 6, a predetermined slurry is supplied to each paper making section as shown by the arrow.

FIG. 7 shows an example in which a three-layer laminated paper is manufactured by a combination machine having two mesh portions and one long mesh portion between the mesh portions. m-
An aqueous slurry (52) of aramid fibrid and m-aramid fiber is prepared, and a head box (53) in a long net portion.
And an aqueous slurry of polyester fibrid or polyester fiber only (54) is further laminated, and m -aramid fibrids and m -aramid fibrids are further added to the second mesh portion (55).
By making from an aqueous slurry (56) between de fibers, resulting 3
The wet paper web (57) is put into a Yankee dryer (5
Dried 8) shall be the three-layer combination papers. Also in FIG. 7, a predetermined slurry is supplied to each paper making section as indicated by an arrow.

FIG. 8 shows, for example, a three-layer laminated paper manufactured by the method shown in FIGS. In this example, the three-layer laminated paper (61) of the intermediate material is heated on both surfaces (m-aramid layer) by a preheating roll (62) (63) at 250 to 340 ° C. After heating and pressing between a pair of calender rolls (64) and (65) at ~ 250 ° C, it is immediately cooled by cooling rolls (66) and (67) to a temperature at which the polyester does not flow, and a three-layer laminated sheet ( 68).

In the examples shown in FIGS. 1 and 8, the laminated sheet obtained by calendering in this manner is basically a three-layer sandwich of m-aramid paper layer / polyester film layer / m-aramid paper layer. Polyester is melt-impregnated into the surface layer of the m-aramid paper layer at each interface of the structural paper to form a strong bond at each interface. 2 and 5
Is basically a two-layered paper composed of an m-aramid paper layer and a polyester film layer.
-Polyester is melt impregnated into the surface layer of the aramid paper layer.
The aramid paper layer and the polyester film layer form a strong bond.

[0041]

The present invention will be described below in detail with reference to examples. However, these are for describing specific examples of the present invention, and do not limit the present invention.

The intrinsic viscosity of poly-m-phenyleneisophthalamide in this example is a value measured at 25 ° C. in an N-methyl-2-pyrrolidone solution, and the intrinsic viscosity of polyester is o-chloro-phenol. This is a value measured at 35 ° C. for the solution.

The dielectric breakdown resistance (BD) of the laminated sheet
V) is a value measured based on JIS C-211.

Example 1 (Production of m-aramid paper) Poly-m-phenylene isophthalamide having an intrinsic viscosity of 1.35 and containing no inorganic salt, produced by the interfacial polymerization method described in JP-B-47-10863. Was converted into a fiber by a wet spinning method described in JP-B-48-17551. The fiber had a strength of 4.5 g / de and an elongation of 18%. This fiber was cut into a fiber length of 6 mm for use.

Using the same polymer, a diameter of 150 m combining a stator and a rotor described in JP-B-52-151621.
The fibrid was manufactured using a m-sedimentation apparatus (pulp-like particle manufacturing apparatus). The resulting fibrids had a freeness of 90 ml as a Canadian standard freeness.

The fibrid was dispersed in water with an industrial pulper, and further treated with a disc refiner and a high-speed disintegrator to obtain a fibrid slurry. On the other hand, the above fibers were dispersed in water using a dedicated industrial pulper and mixed with the above fibrid slurry. The mixing ratio was fiber / pulp (weight ratio) = 60/40.

The mixed slurry is formed on a Fourdrinier paper machine,
The paper was dried after dewatering to obtain m-aramid paper having a basis weight of 40 g / m ² . The resulting paper, after drying, has a density of 0.3
01 g / cm ³ , strength 1.6 kg / m in MD (vertical) direction
m ² , CD (transverse) direction: 1.1 kg / mm ² , air permeability was 10 minutes / 100 ml by Gurley method. (Production of polyester film) Polyethylene terephthalate obtained from dimethyl terephthalate and ethylene glycol was formed into a film by a melt extrusion method and biaxially stretched to obtain a stretched film having a thickness of 0.05 mm. The intrinsic viscosity of the polyester constituting the film is 0.7, and the melt viscosity of the polyester is 550 at 220 ° C.
It was 00 poise.

(Production of Two-Layer Laminated Sheet) Using the m-aramid paper and the polyester film, lamination and calendering were performed according to the method shown in FIG. That is, after sufficiently drying the obtained m-aramid paper, it is preheated by a preheating roll having a surface temperature of 280 ° C., and then superposed on the above polyester film, and the high temperature roll (m-aramid paper side) is 220 ° C. Heating and pressurizing and quenching were performed under the condition that the roll (polyester film side) was 170 ° C and the cooling roll was 50 ° C.

A cross section of the obtained laminated sheet was taken and observed with a microscope. As a result, the polyester film layer and the m-aramid paper layer were in close contact with each other, and almost at the interface between both layers, the surface layer of the m-aramid paper layer was almost completely removed. Melt impregnation of the polyester with a uniform thickness was observed. (Production of a three-layer laminated sheet) Using the two-layer laminated sheet as an intermediate material, a three-layer laminated sheet was produced from the intermediate material and the polyester film according to the method shown in FIG. That is, two layers of the intermediate material are prepared, each is preheated by a preheating roll having a surface temperature of 200 ° C., and then the polyester layers of the upper and lower intermediate materials are butted together, and the polyester film is superposed so as to sandwich the polyester film therebetween. Heat and pressure processing was performed at a linear pressure of 200 kg / cm using a calender roll at 220 ° C., followed by cooling with a water-cooled cooling roll.

The obtained laminated sheet has a basis weight of 260 g /
m ² , tensile strength is 6.6 kg / m in MD (length) direction
m ² , CD (width) direction was 4.3 kg / mm ² , and elongation was 13% in MD (length) direction and 9% in CD (width) direction. The dielectric breakdown voltage of this laminated sheet is 35.2 kV.
/ Mm, when the insulating oil was dripped on the surface, it permeated well.

A cross section of the obtained laminated sheet was taken and observed with a microscope. As a result, a three-layer structure in which a polyester film layer was present between the upper and lower m-aramid paper layers was formed, and the upper and lower m-aramid layers were formed. A tight bond between the paper layer and the polyester layer was observed.

Comparative Example 1 The same m-aramid paper and polyester film as in Example 1 were laminated and heated and pressed by a flat plate press at the same temperature in the upper and lower directions. At this time, the temperature is set to 180 to 2
The pressure was changed over 10 to 100 kg / cm ² over 30 ° C., and various examinations were performed.
-A good laminated sheet in which polyester was impregnated over the entire surface of the aramid paper was not obtained.

[Comparative Example 2] In the production of polyester, a copolymerized polyester was produced using a mixture of 60 mol of terephthalic acid and 40% of isophthalic acid as a dicarboxylic acid and using 100% of ethylene glycol as a glycol component. A film-stretched copolyester film was obtained. This copolymer polyester film had a thickness of 0.050 mm and an intrinsic viscosity of 0.54.

This film was prepared in the same manner as in Comparative Example 1
When heated and pressed with the aramid paper, the molten polyester penetrated to the center of the m-aramid paper and locally aggregated.

Comparative Example 3 In Example 1, a non-woven fabric of m-aramid fiber produced by the method described in Japanese Patent Publication No. 2-15654 was used instead of the m-aramid paper. This nonwoven fabric had a density of 1.03 g / cm ³ , a tensile strength in the MD (longitudinal) direction of 4.0 kg / 15 mm, and an air permeability of 35 seconds / 100 ml by the Gurley method.

This nonwoven fabric and the same polyester film as in Example 1 were heated and pressed in the same manner as in Comparative Example 1. The molten polyester generally penetrated into the m-aramid fiber non-woven fabric by this pressure and heat treatment, and did not form a good laminate.

[Example 2] (Production of two-layer laminated paper) As in Example 1, using m-aramid fiber and m-aramid fibrid, fiber / fibrid (weight ratio) = 60/40. Was prepared.

On the other hand, polyester fibers (fineness: 4 de, fiber length: 6 mm) produced from the same polymer as in Example 1 were dispersed in water with an industrial pulper, and further treated with a disc refiner and a high-speed disintegrator to obtain a polyester fiber slurry. Obtained.

In order to combine these two slurries, the apparatus shown in FIG. 3 was partially modified (one of the circular nets was changed to a long net) to provide a combination machine having a circular net and a long net. using, m- aramid fibrids and mixed slurry of m- aramid fibers in long network, and papermaking a slurry of only the polyester fiber round net paper making superposed after rising dehydration, 2 a basis weight of 80 g / m ² A laminated paper was obtained.
In this paper, the basis weight of the mixed layer of m-aramid fibrids and m-aramid fibers was 40 g / m ² , and the basis weight of the polyester fiber layer was 40 g / m ² . The physical properties of this paper
After drying, density 0.298 g / cm ^3, tensile strength was MD (longitudinal) direction 1.5kg / mm ^2, CD (transverse) direction 1.0 kg / mm ^2. Similarly, m-
Aramid fibrid and m-aramid fiber paper (4
0 g / m ² ) was prepared and dried, and the air permeability was 8.5 minutes / 100 ml by the Gurley method.

(Production of Laminated Sheet) The laminated paper was calendered according to the method shown in FIG. That is, heating is performed from the m-aramid side with a preheating roll having a surface temperature of 220 ° C., and subsequently, the linear pressure is 200 kg using a roll where the m-aramid side is 250 ° C. and the polyester side is not heated.
/ Cm, and immediately after the calendering, the sheet was brought into contact with a cooling roll through which cooling water at normal temperature was passed to rapidly cool the sheet. The processing speed at this time was 30 m / min.

The tensile strength of the obtained laminated sheet is MD
9.2 kg / mm ² in the (length) direction, CD (width) direction 6.
1kg / mm ² , elongation 14% in MD (length) direction, CD
It was 12% in the (width) direction. The dielectric breakdown voltage (BDV) of this laminated sheet was 48.2 kV / mm, indicating good insulating properties.

Example 3 In this example, a sheet was produced by laminating the laminated sheet obtained in Example 2 with the same polyester film as in Example 1 sandwiched, according to the method shown in FIG. It is an example.

The two two-layer laminated sheets obtained in Example 2
The temperature was increased along the m-aramid side on a preheating roll of 20 ° C., and the two sheets were arranged so that the polyester layers were abutted against each other. ° C, linear pressure 200kg
/ Cm at a processing speed of 20 m / min.

Thus, a good three-layer laminated sheet composed of m-aramid paper layer / polyester film layer / m-aramid paper layer was obtained. The tensile strength of this laminated sheet is MD
9.3 kg / mm ² in the (length) direction, CD (width) direction 6.
2kg / mm ² , elongation 14% in MD (length) direction, CD
It was 13% in the (width) direction. The dielectric breakdown voltage (BDV) of this laminated sheet was 58.2 kV / mm, indicating good insulation properties.

Example 4 (Production of polyester fibrid) A mixture of 60% terephthalic acid and 40% isophthalic acid was used as a dicarboxylic acid, and ethylene glycol 100 was used as a glycol component.
% Of a copolymerized polyester having an intrinsic viscosity of 0.60, which was dissolved in N-methyl-2-pyrrolidone to form a solution having a polymer concentration of 20% by weight.
Polyester fibrids were produced using a 20% by weight aqueous solution of -methyl-2-pyrrolidone and a precipitation apparatus described in JP-B-52-151621. The resulting polyester fibrid has a freeness of 2 according to the Shopper Riegler method.
It was 0 ° SR. This is Canadian standard freeness 600m
l.

(Production of laminated paper) A mixed slurry of fiber / fibrid (weight ratio) = 60/40 was prepared using m-aramid fiber and m-aramid fibrid in the same manner as in Example 1.

On the other hand, the above polyester fibrid was dispersed in water with an industrial pulper, and further treated with a disc refiner and a high-speed disintegrator to obtain a polyester fibrid slurry.

In order to combine these two kinds of slurries, the apparatus shown in FIG. 3 was partially modified (one of the circular nets was changed to a long net), and a combination machine equipped with a circular net and a long net was used. , A mixed slurry of m-aramid fibrids and m-aramid fibers is made into a long net, and a polyester fibrid slurry is made into a circular net, and after being dewatered and superimposed, they are superposed to form a two-layer sheet having a basis weight of 80 g / m ² . I got a joint paper.
The basis weight of the mixed layer of m-aramid fibrids and m-aramid fibers in this paper was 40 g / m ² , and the basis weight of the layer composed of only polyester fibrid was 40 g / m ² .
The paper is after drying, density 0.300 g / cm ^3, strength of MD (length) direction 1.6kg / mm ^2, CD (width) direction 1.2 kg / mm ^2. Similarly, a m-aramid fibrid and m-aramid fiber paper (40
g / m ² ) and dried, and the air permeability was 9 minutes / 100 ml by the Gurley method.

(Production of Laminated Sheet) This laminated paper 2
The sheet was laminated with one polyester film similar to that in Example 3 to form an integral sheet. That is, as shown in FIG. 5, the above laminated paper was heated from the m-aramid layer side with a preheating roll having a surface temperature of 180 ° C., and then the polyester fibrid layer side of this paper was abutted with each other. Sandwich a polyester film at a temperature of 250
At a temperature of 200 ° C and a linear pressure of 200 kg / cm.
It was immediately cooled by a cooling roll. The calendering speed at this time was 30 m / min.

The resulting m-aramid paper layer / polyester film layer / m-aramid paper layer laminated sheet had a tensile strength of 4.8 kg / mm ² in the MD (length) direction and a CD (width).
3.2 kg / mm ^{2 in} the direction, MD (length) direction 18
%, And 17% in the CD (width) direction. In addition, the dielectric breakdown voltage (BDV) of this laminated sheet was 45.5 kV / mm, indicating good insulation. When the insulating oil was dripped on this surface, it permeated well.

Example 5 A mixed slurry of m-aramid fibrid and m-aramid fiber was prepared in the same manner as in Example 1. The freeness of this mixture was about 35 ° SR (Canadian standard freeness 350 ml). On the other hand, the same polyester fibrid as in Example 6 was treated with a high-speed disintegrator and dispersed in water to form a slurry. The freeness of the polyester fibrid after the dispersion treatment is about 30 ° SR by the Shopper Riegler method (Canadian standard freeness 450 ml).
Met.

A mixed slurry of m-aramid fibrid and m-aramid fiber was mixed with a combination machine (test paper machine) having two round papermaking sections and a fourdrinier section therebetween as shown in FIG. Then, the polyester fibrid slurry was supplied to a fourdrinier papermaking section, and papermaking was performed. That is, in each of the web making sections,
The g / m ² wet paper was formed into a 40 g / m ² wet paper in the Fourdrinier papermaking section, these three layers were overlapped and squeezed, followed by drying with a Yankee dryer.

The tensile strength of the obtained laminated paper is MD
2.4kg / 15mm in the direction, 1.7kg / 15 in the CD direction
mm, and the elongation is 3.5% in the MD direction and 2.5 in the CD direction.
%Met. The web of m-aramid made in the web making section was collected and dried, and the air permeability was 7 minutes / 100 m.
l.

This was heated by a preheating roll at 180 ° C., calendered at a temperature of 240 ° C. and a linear pressure of 200 kg / cm, and then quenched by a cooling roll (water-cooled roll) in which water at normal temperature was circulated. And wound up.

The laminated sheet thus obtained has a tensile strength of 25.2 kg / 15 mm in the MD direction and 141.15 kg in the CD direction.
8kg / 15mm, elongation is 8.9% in MD direction, 7.8% in CD direction, and dielectric breakdown resistance (BDV) is 35.2K
V. When the insulating oil was dripped on the surface of the laminated sheet, it was well absorbed.

[Embodiment 6] The prototype m produced in Embodiment 1
-A three-layer sheet was prepared using aramid paper and the same polyester film as in Example 1 by the method shown in FIG.

That is, two prototype m-aramid papers of Example 1 were heated along a preheating roll having a surface temperature of 300 ° C., a polyester film was interposed therebetween, and a temperature of 240 ° C. and a linear pressure of 200 kg / m were applied. The sheet was calendered under the condition of cm, subsequently cooled with a water-cooled roll, and then taken out.

Thus, a good laminated sheet in which the polyester film layer was tightly bonded between the m-aramid paper layers was obtained. The strength of this laminated sheet is 9.0 kg /
15mm, CD direction 6.0kg / 15mm, elongation MD
12% in the direction and 11% in the CD direction.
DV) was 38.1 KV. When the insulating oil was dropped on the surface of the laminated sheet, it was observed that the insulating oil was well absorbed.

[0079]

According to the method of the present invention, only the surface layer of the m-aramid paper layer is substantially uniformly impregnated with the polyester, and this portion exerts an adhesive effect, whereby the m-aramid paper and the polyester film layer are tightly packed. A good laminated sheet joined and integrated into a sheet is obtained. Then, during calendering, the molten polyester penetrates into the entire m-aramid paper layer,
-Since it does not agglomerate in aramid paper, the m-aramid paper layer maintains its original permeability and air permeability, and exhibits good electrical and mechanical properties due to the polyester film layer.

Therefore, the laminated sheet according to the method of the present invention is particularly suitable as an electric insulating material used by impregnating with resin or electric insulating oil, but is also useful as a composite structural material.

[Brief description of the drawings]

FIG. 1 shows a method for producing a three-layer laminated sheet composed of m-aramid paper layer / polyester film layer / m-aramid paper using two separately produced m-aramid paper layers and one polyester film layer according to the method of the present invention. Simplified cross-sectional view showing an example

FIG. 2 is a simplified cross-sectional view showing an example in which one layer of a polyester film is superposed on one side of an m-aramid paper layer to produce a two-layer laminated sheet according to the method of the present invention.

FIG. 3 is a simplified cross-sectional view showing an example of producing a two-layer laminated paper which can be used as an intermediate material in the method of the present invention by lamination using a circular paper machine.

FIG. 4 is a simplified cross-sectional view showing an example of manufacturing a two-layer laminated paper which can be used as an intermediate material in the method of the present invention by lamination using a fourdrinier paper machine.

FIG. 5 is a simplified cross-sectional view showing an example of manufacturing a two-layer laminated sheet by the method of the present invention using a two-layer laminated paper as an intermediate material.

FIG. 6 is a simplified cross-sectional view showing an example of producing a three-layer laminated paper which can be used as an intermediate material in the method of the present invention by lamination using a circular paper machine.

FIG. 7 is a simplified diagram showing an example of manufacturing a three-layer laminated paper which can be used as an intermediate material of the method of the present invention by a lamination method using a combination machine combining a round paper machine and a fourdrinier paper machine. Cross section sketch

FIG. 8 is a simplified cross-sectional view showing an example of manufacturing a laminated sheet according to the method of the present invention using a three-layer laminated paper as an intermediate material.

[Explanation of symbols]

1,2,6: m-aramid paper 3,7: polyester film 4,68: product laminated sheet (three-layer structure sheet) 8, 37: product laminated sheet (two-layer structure sheet) 11, 12, 17, 32, 62, 63: Preheating rolls 13, 14, 18, 19, 33, 34, 64, 65: Calender rolls 15, 16, 20, 35, 36, 66, 67: Cooling rolls 21, 23, 41, 43, 45: Round paper making section 26, 27: Fourdrinier paper machine head box 51, 55: Round machine paper making section of combination machine 53: Long net making section head box of combination machine 22, 42, 46, 52, 56: Mixed slurry of m-aramid fibrid and m-aramid fiber 24, 44, 54: Slurry of polyester fibrid (or polyester fiber) 25 , 28, 47, 57: Laminated paper 58: Yankee dryer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-105882 (JP, A) JP-A-2-160309 (JP, A) JP-A-2-122917 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) B32B 1/00-35/00 D21H 11/00-27/42 B29C 65/00-65/82

Claims (10)

(57) [Claims] 1. An m-aramid fibrid and m-arami
In producing a laminated sheet composed of a synthetic paper layer and a polyester film layer made of paper fiber and a synthetic paper layer and a polyester film layer , a calendering device
Preheating the synthetic paper layer before being supplied to the method for producing a laminated sheet, wherein the temperature of the synthetic paper layer is subjected to calendering under the conditions become hotter than the temperature of the polyester film layer, and then rapidly cooled . 2. The method according to claim 1, wherein the polyester film layer is a stretched or unstretched polyester film. 3. The method for producing a laminated sheet according to claim 1, wherein the polyester film layer is a layer obtained by heating and pressing polyester fibrid. 4. The polyester film layer to be laminated is o-
The method for producing a laminated sheet according to claim 2 or 3, wherein the method comprises a polyester having an intrinsic viscosity of 0.6 or more measured at 35 ° C in a chlorophenol solution. 5. The synthetic paper layer to be laminated has an air permeability measured by the Gurley method of 5 minutes / 100 ml to 1000 minutes / 100 ml.
The method for producing a laminated sheet according to claim 1, wherein 6. A calendering process, wherein the synthetic paper layer side is 250
° C or higher, and the polyester film layer side
0 ° C. or more and 5 ° C. below the glass transition point of the polyester
The method for producing a laminated sheet according to any one of claims 1 to 5, wherein the method is performed under a condition of a temperature higher than 0 ° C. 7. The method according to claim 1, wherein the temperature of the polyester layer in the calendering is set to a temperature at which the melt viscosity of the polyester becomes 10,000 poise or more.
A method for producing a laminated sheet according to claim 6. 8. The method for producing a laminated sheet according to claim 1, wherein the laminated sheet is cooled to a temperature not higher than the glass transition temperature of the polyester within 10 seconds after calendering. 9. The method for producing a laminated sheet according to claim 1, wherein the laminated sheet is a two-layer laminated sheet in which a polyester film layer is laminated on one side of a synthetic paper layer. 10. The laminated sheet according to claim 1, wherein the laminated sheet is a three-layer laminated sheet in which a polyester film layer is sandwiched between two synthetic paper layers. Manufacturing method.