JPH04240293A - Method for calendering - Google Patents

Abstract

PURPOSE:To provide a calendering method for preventing damages to thermopressing metallic calender rolls caused by the blocking of short fibers and pulp in a heat-resistant nonwoven fabric or by foreign matters contaminated therein. CONSTITUTION:The title calendering method is characterized by treating a nonwoven fabric with low temperature metal/metal calendering rolls at <=50 deg.C under a linear pressure of >=100kg/cm before the following a calendering, in a method for calendering the nonwoven fabric containing an aromatic polyamide pulp and aromatic polyamide short fibers in amounts of >=20wt.%. Since the blocking of the short fibers and the pulp in the nonwoven fabric and foreign matters contaminated therein, etc., are compressed by the low temperature metal/metal calendering process before the thermopressing calendering process, the damages to the thermopressing calender rolls can be prevented.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a heat-pressure calendering method for heat-resistant non-woven fabric, in which aromatic polyamide short fibers and aromatic polyamide pulp are bundled or heat-press metal calendering is performed using foreign matter mixed in the non-woven fabric. -Regarding a processing method for preventing damage to rolls.

0002

[Prior Art] Conventionally, heat-pressure calendering methods for heat-resistant nonwoven fabrics containing aromatic polyamide pulp and aromatic polyamide staple fibers have been disclosed in Japanese Patent Publications No. 35-11851 and Japanese Patent Publication No. 36-16460. Kosho 37-573
Publication No. 2 and the like describes that aromatic polyamide fibrids and aromatic polyamide staple fibers are mixed and then subjected to hot-pressure calender processing.

However, the hot-pressure calendering method described in the above-mentioned publication is a one-stage nip calendering method, and when the product is processed for a long period of time, foreign matter mixed in the nonwoven fabric and short fibers may cause thermal damage. There is a problem in that the surface of the pressure metal calender roll is damaged and product quality is degraded.

0004

OBJECT OF THE INVENTION The object of the present invention is to solve the problem of heat-pressing metal calenders caused by foreign matter mixed in heat-resistant nonwoven fabrics and short fibers as described above.
An object of the present invention is to provide a calendering method that prevents damage to the surface of a roll.

[0005]

DESCRIPTION OF THE INVENTION The present invention provides a method for calendering non-woven fabric containing aromatic polyamide pulp and aromatic polyamide staple fibers at 20% by weight or more using metal/metal calender rolls at 200 degrees C or higher. This calendering method is characterized in that, before the processing, the non-woven fabric is treated with a metal/metal calender roll at a temperature of 50 degrees Celsius or less and a linear pressure of 100 kg/cm or more.

The aromatic polyamide used in the present invention is a conventionally known (a) condensed polyamide of a dicarboxylic acid having an aromatic ring and a diamine having an aromatic ring, and (b) a condensed polyamide of an aminocarboxylic acid having an aromatic ring. (c) A polyamide obtained by copolymerizing the above (a) and (b).

[0007] Aromatic polyamide pulp, for example,
These are described in Japanese Patent Publication No. 5-11851, Japanese Patent Publication No. 37-5732, and the like.

[0008] The aromatic polyamide short fibers preferably have a single filament fineness of 20 deniers or less and a fiber length of 3 to 60 mm. .

If the amount of aromatic polyamide pulp and aromatic polyamide short fibers is less than 20% by weight, the blending ratio is low and the calender roll will be damaged even if the processing method of the present invention is not applied. Never.

[0010] The non-woven fabric is a non-woven fabric containing aromatic polyamide pulp and aromatic polyamide short fibers in an amount of 20% by weight or more. Other ingredients are polyethylene terephthalate fiber,
polyvinyl alcohol fiber, glass fiber, natural pulp,
Mica or the like may be included, but there is no particular limitation.

[0011] Processing of non-woven fabric is done by metal/metal calendaring.
50°C before calendering at 200°C or higher using a
It is necessary to process with a metal/metal calender roll at a temperature of 100° C. or less and a linear pressure of 100 kg/cm or more.

[0012] The temperature of the metal/metal calender roll is 50°C.
If the temperature rises above 10°C, the hardness of the metal/metal calender roll decreases, making it difficult to completely compress foreign matter and short fibers in the non-woven fabric. During subsequent hot-pressure calendering, the work fabric damages the hot-press metal/metal calender roll.

[0013] Also, if the processing pressure of the low-temperature metal/metal calender roll is less than 100 kg/cm, it will be difficult to completely compress the foreign matter and bound short fibers in the non-woven fabric. - The treated non-woven fabric damages the hot press metal/metal calender roll during subsequent hot press calendering.

[0014] Even when the material of the low-temperature metal/metal calender roll is a metal/elastic calender roll, it is not possible to completely compress the foreign matter and bound short fibers in the non-woven fabric. Damage to the hot pressure metal/metal calender roll during hot pressure calendering.

[0015]

Effects of the Invention The present invention prevents damage to hot press metal/metal calender rolls caused by foreign matter or bound short fibers in the non-woven fabric when processing heat-resistant non-woven fabric.

[0016]

[Examples] The present invention will be explained in more detail with reference to Examples below. In the examples, the basis weight and degree of damage to the calender roll were evaluated by the following methods. (1) Basis weight: Measured according to JIS-P-8124. (2) Calendar roll damage degree: width 30cm x length 2
000 m of unfinished cloth was processed and the degree of damage to the surface of the calender roll was visually determined. Items with more damage were rated as poor, and items with less damage were rated as good.

[0017]

[Example 1, Comparative Examples 1 to 3] Commercially available polymetaphenylene isophthalamide fibers were cut into lengths of 6 mm to obtain polymetaphenylene isophthalamide short fibers for paper making with a single yarn fineness of 2 denier and a fiber length of 6 mm. Ta. Next, the single yarn fineness is 1.1.
Undrawn short polyethylene terephthalate fibers having a fiber length of 5 mm were mixed, dissociated, and dispersed together with the aforementioned polymetaphenylene isophthalamide short fibers using a pulper at a concentration of 1%.

Further, pulp for paper making was produced by the following method.

First, polymetaphenylene isophthalamide was produced by the interfacial polymerization method described in Japanese Patent Publication No. 47-10863. This polymer has an intrinsic viscosity (I.V) of 1.35 when dissolved in N-methyl-2-pyrrolidone.
The polymer does not contain any inorganic salts. This polymer was dissolved in N-methyl-2-pyrrolidone to a polymer concentration of 12.5%. On the other hand, N-methyl-2-
Water was added to pyrrolidone to prepare an aqueous solution (concentration: 3% by weight), which was used as a precipitant.

[0020] This polymer solution and precipitant were
2-15621, a chamber having a polymer solution inlet, a precipitant inlet, and a slurry outlet, a rotor installed in the chamber, and a stator fixed to the inner wall of the chamber. Using a sedimentation funnel consisting of -, the mixture was injected from each injection port, and the rotor was rotated at high speed to form pulp.

[0021] Using the obtained pulp, use a pulper, a high-speed disintegrator, and a disc clarifier to reduce the slurry concentration to 0.
．． An aqueous slurry having a Canadian standard filtration rate of 110 ml was prepared at 3%.

Next, the short fiber mixed slurry and the pulp slurry were mixed at a mixing ratio as shown in Table 1, and paper was made using a Fourdrinier paper machine. Thereafter, processing was performed under the calender conditions as shown in Table 1.

The obtained physical properties are shown in Table 1.

As shown in Table 1, Example 1 was good with very little damage to the calender roll.

In (Comparative Example 1), the high temperature of the low-temperature calender made it difficult to completely compress short fibers and pulp bundles or foreign matter in the nonwoven fabric, and the hot-pressure calender was not used.
The degree of roll damage was poor compared to (Example 1).

(Comparative Example 2) also had a poor degree of damage to the hot-pressure calender rolls compared to (Example 1) because the pressure of the low-temperature calender was low.

In (Comparative Example 3), since the low-temperature calender material is metal/elastic, it is difficult to completely compress short fibers and pulp bundles or foreign matter in the nonwoven fabric, and the hot-pressure calender roll is difficult. The degree of damage was poor compared to (Example 1).

[0028]

[Table 1]

Claims (1)

[Claims] Claim 1: A method of calendering non-woven fabric containing aromatic polyamide pulp and aromatic polyamide short fibers at 20% by weight or more using a metal/metal calender roll at 200 degrees C or higher, in which: Heat the fujofu to 50 degrees C.
The following is a calender processing method characterized by processing with a metal/metal calender roll having a linear pressure of 100 kg/cm or more.