Processing method of vulcanized fiber

Abstract

To provide a processing method of a vulcanized fiber that can perform mass-processing of a relatively thick vulcanized fiber suitable for use with an industrial product to the same shape.SOLUTION: A processing method of a vulcanized fiber having a thickness of a vulcanized fiber base material of 0.8 mm or over includes steps of: preparing a vulcanized fiber base paper; soaking the base paper in a reaction agent for swelling and gelatinizing a surface thereof; soaking the base paper in a solution with lower concentration than the reaction agent for deliquoring the reaction agent; drying the deliquored base paper to obtain a vulcanized fiber base material; adjusting a water content of the vulcanized fiber base material; and subjecting the water content-adjusted vulcanized fiber base material to mold press processing by using a mold warmed up to 90-180°C to obtain a vulcanized fiber. In the mold press step, compression and opening are run at least once.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for processing a vulcanized fiber, and more particularly to a method for processing a vulcanized fiber that suppresses tearing, wrinkling, and distortion during mold press processing by using a relatively simple device while subjecting the vulcanized fiber to mold press processing. [Background technology]

[0002] Vulcanized fiber, also called vulcan fiber, is a tough organic industrial material produced by immersing base paper, mainly made of natural cellulose such as wood pulp and cotton pulp, in a reactive chemical that swells and gelats the pulp, such as an aqueous solution of zinc chloride, to swell and gelatinize the surface of the base paper, then removing the reactive chemical with a cleaning solution to stop the swelling and gelatinization reaction, and then drying and finishing. Vulcanized fiber is an environmentally friendly industrial material, as the main fiber is made of natural cellulose fiber, and is biodegradable and suitable for clean incineration treatment when discarded.

[0003] While the toughness of vulcanized fiber is an advantage as a material, its toughness also has the disadvantage that it is difficult to process and requires a long time to mold. As a proposal for improving the processability of vulcanized fiber, Patent Document 1 proposes a method in which thin vulcanized fiber of 0.18 to 0.35 mm is immersed in water and shaped into a desired shape by hand. Similarly, Patent Document 2 proposes a method in which thin vulcanized fiber of 0.2 to 0.5 mm is immersed in water and shaped into a desired shape.

[0004] The method described in Patent Document 1 is used for processing hobby materials and teaching materials for beginners and elementary school students, and is suitable for processing relatively thin vulcanized fibers having a thickness of 0.18 to 0.35 mm, but is not suitable for processing vulcanized fibers having a thickness of more than 0.35 mm. The technology described in Patent Document 2 is used for photo holders, but like Patent Document 1, is not suitable for processing vulcanized fibers having a thickness of more than 0.5 mm. In other words, neither of the technologies described in Patent Documents 1 and 2 is suitable for processing vulcanized fibers having a thickness of more than 0.5 mm, and they cannot be said to be sufficient proposals for finishing a large number of vulcanized fibers having a thickness of 0.8 mm or more into the same shape, which is suitable for industrial products. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 11-267372 [Patent Document 2] Utility model registration No. 3052183 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a method for processing vulcanized fibers, which is capable of mass-processing relatively thick vulcanized fibers of the same shape suitable for use in industrial products.

[0007] Another object of the present invention is to provide a method for processing vulcanized fiber, which, while subjecting vulcanized fiber to mold press processing, suppresses tearing, wrinkling, and distortion during mold press processing with a relatively simple device.

[0008] Further objects and advantages of the present invention will become readily apparent to those skilled in the art by reading the following description. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the vulcanized fiber processing method of the present invention includes a base paper preparation step of preparing a vulcanized fiber base paper, a gelatinization step of immersing the vulcanized fiber base paper in a reactive chemical to swell and gelatinize the surface of the vulcanized fiber base paper, a deliquification step of immersing the vulcanized fiber base paper in a solution having a lower concentration than the reactive chemical to remove the reactive chemical, a drying step of drying the vulcanized fiber base paper after the deliquification to obtain a vulcanized fiber substrate, a moisture adjustment step of adjusting the moisture of the vulcanized fiber substrate, and a mold pressing step of performing a mold pressing process on the moisture-adjusted vulcanized fiber substrate using a mold heated to 90 to 180°C to obtain a vulcanized fiber, wherein the mold pressing step is characterized in that pressure and release are performed at least once, and the thickness of the vulcanized fiber substrate is 0.8 mm or more.

[0010] In a preferred embodiment of the present invention, the moisture content of the moisture-adjusted vulcanized fiber substrate may be 10 to 18%.

[0011] Another configuration example of the vulcanized fiber processing method according to the present invention includes a base paper preparation step of preparing a vulcanized fiber base paper; a gelatinization step of immersing the vulcanized fiber base paper in a reactive chemical to swell and gelatinize the surface of the vulcanized fiber base paper; a deliquification step of immersing the vulcanized fiber base paper in a solution having a lower concentration than the reactive chemical to remove the reactive chemical; a drying step of drying the vulcanized fiber base paper after deliquification to obtain a vulcanized fiber substrate having a moisture content of 10 to 18%; and a mold pressing step of performing a mold pressing process on the vulcanized fiber substrate with the moisture content adjusted using a mold heated to 90 to 180°C to obtain a vulcanized fiber, wherein the mold pressing step is characterized in that pressure and release are performed at least once, and the thickness of the vulcanized fiber substrate is 0.8 mm or more.

[0012] In a preferred embodiment of the present invention, the die used in the die pressing step may be a drawing die.

[0013] In a preferred embodiment of the present invention, the pressurization and release performed in the die pressing step may be performed 1 to 10 times.

[0014] In a preferred embodiment of the present invention, the density of the vulcanized fiber substrate is 1.20 to 1.35 g / cm 3 may be also possible. Effect of the Invention

[0015] According to the present invention, vulcanized fiber can be processed relatively easily using a mold while suppressing tears, wrinkles, and distortion. [Brief description of the drawings]

[0016] [Figure 1] 1 is a general flow chart showing an example of a manufacturing process for a vulcanized fiber according to the present invention. [Diagram 2] 1 is a table showing the treatment conditions of vulcanized fibers according to Examples and Comparative Examples and the evaluation of the vulcanized fibers. [Diagram 3] FIG. 1 is a diagram showing an example of the appearance of a vulcanized fiber that has been subjected to mold pressing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will be described below, but it should not be construed as being limited to these embodiments.

[0018] The method for processing vulcanized fiber according to the present invention includes a base paper preparation step for preparing a vulcanized fiber base paper, a gelatinization step for immersing the vulcanized fiber base paper in a reactive chemical to swell and gelatinize the surface of the vulcanized fiber base paper, a deliquification step for immersing the vulcanized fiber base paper in a solution with a lower concentration than the reactive chemical to remove the reactive chemical, a drying step for drying the vulcanized fiber base paper after deliquification to obtain a vulcanized fiber substrate, a moisture adjustment step for adjusting the moisture of the vulcanized fiber substrate, and a mold pressing step for performing a mold pressing process on the moisture-adjusted vulcanized fiber substrate using a mold heated to 90 to 180°C to obtain a vulcanized fiber, wherein the mold pressing step is characterized in that pressure and release are performed at least once, and the thickness of the vulcanized fiber substrate is 0.8 mm or more. The moisture of the vulcanized fiber substrate may be adjusted to a desired moisture content by adjusting the drying conditions in the drying step without providing a special moisture adjustment step.

[0019] An example of the manufacturing process of the vulcanized fiber according to the present invention is shown in Fig. 1. In this specification, the product at the stage where the drying process 50 is completed is referred to as the "vulcanized fiber substrate," and the product at the stage where the mold pressing process 70 is completed is referred to as the "vulcanized fiber." The following description will be given with reference to Fig. 1.

[0020] <Base paper preparation process 10> In the present invention, the vulcanized fiber base paper used for the vulcanized fiber may be produced from raw materials, or may be purchased and used according to the conditions. When producing the vulcanized fiber base paper, it is produced from natural cellulose such as wood pulp and cotton pulp. Examples of wood pulp include chemical pulps such as softwood dissolved sulfate pulp (NDSP), softwood bleached kraft pulp (NBKP), softwood unbleached kraft pulp (NUKP), hardwood bleached kraft pulp (LBKP), and hardwood unbleached kraft pulp (LUKP), mechanical pulps such as groundwood pulp (GP) and thermomechanical pulp (TMP), and waste paper pulp such as deinked pulp. One or more types selected from these pulps can be used. For example, a pulp slurry containing 35 to 80 parts by mass of cotton pulp and 65 to 20 parts by mass of NBKP in 100 parts by mass of the total pulp slurry can be used.

[0021] In addition, the pulp slurry for producing vulcanized fiber base paper is preferably adjusted to an appropriate freeness. For example, the freeness after beating is preferably in the range of 400 to 600 ml CSF in terms of Canadian standard freeness (JIS P 8121:1995 "Testing method for freeness of pulp").

[0022] Furthermore, vulcanized fiber base paper made by wet papermaking of cotton fibers such as cotton rag pulp and linters, paper pulp made from wood fibers, non-wood fibers such as kenaf and bamboo pulp, and regenerated cellulose fibers such as rayon can also be suitably used. Organic chemical synthetic fibers and inorganic fibers can also be blended within a range that does not impair the intended effects of the present invention. It is preferable that the vulcanized fiber base paper has appropriate water absorption, air permeability, and uniform texture so that when it is immersed in a reactive chemical that has the property of swelling and gelatinizing the pulp, such as an aqueous zinc chloride solution, the aqueous zinc chloride solution can penetrate uniformly into the base paper.

[0023] <Agglomeration process 20> In the gelatinization step 20, the vulcanized fiber base paper is immersed in a reactive chemical in a conventional manner to swell and gelatinize the surface. Hereinafter, the gelatinization step may be referred to as "vulcanization". The reactive chemical used here may be an appropriate one selected from conventional ones used for swelling and gelatinizing vulcanized fiber, such as an aqueous zinc chloride solution. As an example, when an aqueous zinc chloride solution is used as the reactive chemical, the concentration of zinc chloride is preferably in the range of 65 to 74 Baume (°Be), and the temperature of the aqueous solution during the immersion treatment is preferably in the range of 28 to 55°C.

[0024] When two or more sheets of base paper are used for the vulcanized fiber, these sheets of base paper are laminated in a gelatinization step 20. More specifically, the vulcanized fiber base paper is immersed in a reactive chemical, and then a lamination process is performed in the liquid several seconds later. The lamination step is not necessary for vulcanized fiber made of one sheet of base paper. The reactive chemical used here is not particularly limited as long as it swells and gelats the cellulose fiber, and in addition to an aqueous solution of zinc chloride, N-methylmorpholine-N-oxide, a mixed solution of N-methylmorpholine-N-oxide and a polar liquid, sulfuric acid, etc. can also be used. However, the method using an aqueous solution of zinc chloride is the most industrialized and is the most desirable for mass production.

[0025] <Deliquoring process 30> In the deliquor step 30, the reactive chemicals used in the gelatinization step 20 are removed with a cleaning solution. More specifically, the same reactive chemicals as those used in the gelatinization step 20 are used as the cleaning solution at a lower concentration than the reactive chemicals. For example, when an aqueous zinc chloride solution is used as the reactive chemicals, an aqueous zinc chloride solution with a lower concentration than the aqueous zinc chloride solution used in the gelatinization step 20 is used, and the reactive chemicals are removed by sequentially immersing the paper in multiple cleaning tanks in which the zinc chloride concentration is gradually decreased, or by sequentially decreasing the cleaning solution concentration in a single cleaning tank. When multiple cleaning tanks are used, the cleaning tanks are provided so that the zinc chloride concentration is gradually decreased from the first tank to the final tank, and the cleaning solution in the final tank is a solution containing almost no zinc chloride components or fresh water, and the aqueous zinc chloride solution is removed by sequentially immersing the vulcanized fiber base paper after the gelatinization step 20 in these cleaning tanks. On the other hand, if processing is performed in a single tank, the reaction liquid can be removed by gradually replacing the entire amount of the cleaning liquid in the cleaning tank to gradually reduce the concentration of the solution, or by gradually pouring water into the cleaning tank to reduce the concentration of the cleaning liquid.

[0026] Regarding the concentration of the cleaning solution, for example, if a zinc chloride aqueous solution with a concentration of 65 to 74 Baume is used in the gelatinization step 20, a cleaning solution with a zinc chloride concentration gradually reduced from a zinc chloride aqueous solution with a concentration of 15 to 33 Baume is prepared, and deliquation is performed by the above-mentioned method. Furthermore, in the deliquation step, as disclosed in JP-A-09-302594, in order to promote the removal of reactive chemicals such as zinc chloride, a device having a single-stage or multi-stage vibrating blade plate fixed non-rotatably to a vibration shaft that vibrates in the axial direction may be inserted into the zinc dechlorination tank, i.e., into the cleaning solution in the cleaning tank, and deliquation treatment may be performed while applying vibration to the vibration blade plate with a frequency of 10 to 60 Hz and a vibration width of 2 to 30 mm.

[0027] <Drying process / Finishing process 40> After passing through the deliquification step 30, the vulcanized fiber substrate is obtained through the drying step and the finishing step 40. The drying method used here is not particularly limited, and known drying methods such as hot air drying, microwave drying, infrared drying, and roll dryer drying can be used, and the vulcanized fiber substrate is dried until the desired moisture content is reached. In the finishing step, a cutting process to a predetermined size is performed by a roll winding process or a flat cutting process. If necessary, a calendaring process may be performed to impart smoothness. In addition, if the moisture content of the vulcanized fiber substrate is adjusted at this stage, the drying conditions may be adjusted to a moisture content of 10 to 18% and the substrate may be used in the mold pressing process.

[0028] <Moisture adjustment process 50> In the moisture adjustment step 50, the moisture content of the vulcanized fiber substrate obtained by carrying out the base paper preparation step 10 to the drying and finishing steps 40 is adjusted. The moisture content of the vulcanized fiber substrate is preferably 10 to 18%, more preferably 12 to 17%, and even more preferably 14 to 17%. If the moisture content is less than 10%, the vulcanized fiber substrate does not stretch sufficiently and may tear during the die pressing step. On the other hand, if the moisture content exceeds 18%, the moisture is not removed only during the die pressing step, and distortion may occur due to subsequent moisture release. There is no particular limitation on the method of adding moisture, but it is desirable to make the entire vulcanized fiber substrate absorb water uniformly. Examples of the method include immersing the vulcanized fiber substrate in a container filled with water immediately before die pressing and wiping off excess water with a cloth, or leaving the vulcanized fiber substrate in a humidified space for about 2 to 48 hours to add moisture.

[0029] <Mold pressing process 60> In the present invention, the moisture content of the vulcanized fiber substrate is adjusted, and then the vulcanized fiber substrate is pressed into a mold to produce a desired molded product. In the mold pressing process, the mold is heated and pressed, and the mold temperature is preferably 90 to 180°C, and more preferably 110 to 160°C. If the mold temperature is less than 90°C, moisture does not evaporate sufficiently, and the molded product may become distorted due to subsequent moisture release. If the mold temperature exceeds 180°C, only the surface becomes overdried, and the moisture in the vulcanized fiber becomes non-uniform, which may lead to distortion. In addition, the product may become yellowed due to fading.

[0030] In addition, in the die pressing process, pressure is applied and released at least once. It is preferable to apply pressure and release three times or more, and more preferable to apply pressure and release five times or more. If pressure and release are not applied, moisture will not evaporate sufficiently, which may result in distortion of the molded product. On the other hand, friction occurs every time pressure is applied and released, making the product prone to scratches, so the practical upper limit is 10 times. In addition, if pressure and release are repeated too many times, it will result in a loss in productivity.

[0031] In the present invention, the die used in the die press is preferably a drawing die. Here, the die is a general term for a die made mainly of a metal material for obtaining a product by molding using the plasticity or fluidity properties of the material. Press dies are classified into punching dies, bending dies, drawing dies, compression dies, etc., and among these, drawing dies require the material to have the property of shrinking and expanding, so it is generally difficult to process the vulcanized fiber substrate of cellulose material by die press, but some ingenuity can make it possible to process it using a drawing die. In the present invention, the moisture content of the vulcanized fiber substrate is adjusted before die press processing, making it possible to perform molding processing using a drawing die.

[0032] In the present invention, the density of the vulcanized fiber substrate is not particularly limited, but the higher the density, the easier it is to obtain the elongation that is important in drawing. 3 The desired effect is easily obtained if the concentration is 1.25 to 1.35 g / cm 3Since the density of the vulcanized fiber tends to increase as the thickness of the vulcanized fiber increases, the increased thickness and density have a synergistic effect, making the fiber less susceptible to tearing or wrinkling.

[0033] The thickness of the vulcanized fiber substrate used in the present invention is 0.8 mm or more. Relatively thin vulcanized fibers can be molded by hand, but vulcanized fibers with a thickness of 0.8 mm or more that are also used for industrial products are strong and difficult to mold by hand. According to the processing method of the present invention, it is possible to mold a large amount of strong vulcanized fiber substrates with a thickness of 0.8 mm or more that can be used for industrial products into the same shape. According to the present invention, the thicker the vulcanized fiber substrate, the greater the elongation, so the effect of the present invention can be more significantly exhibited. The thickness of the vulcanized fiber substrate is preferably 1.2 mm or more, and more preferably 1.6 mm or more. Since a vulcanized fiber substrate with a thickness exceeding 2.5 mm significantly reduces production efficiency, the upper limit of the actual thickness is 2.5 mm. It should be noted that all of these values ​​are the thickness at the completion of the drying and finishing process 40, and it is possible that the thickness of the vulcanized fiber as a product after the mold pressing process 60 is completed may be thinner than when it was in the form of a vulcanized fiber substrate. EXAMPLES

[0034] The processing method for vulcanized fiber according to the present invention will be specifically described below using examples, but the present invention is not limited to these examples. In the examples, "parts" and "%" respectively mean "parts by mass" and "% by mass" unless otherwise specified. The number of parts added is a value calculated as a solid content.

[0035] Example 1 <Preparation of vulcanized fiber base paper> A slurry consisting of 70 parts by mass of cotton linters and 30 parts by mass of NBKP adjusted to 500 ml of CSF was used as a papermaking raw material and paper was made on a Fourdrinier papermaking machine to obtain a vulcanized fiber base paper. <Preparation of vulcanized fiber substrate> Each of the 14 sheets of vulcanized fiber base paper was immersed in an aqueous solution of zinc chloride (69°Be, 44°C) to swell and gelatinize the surface of the base paper, and the base papers were laminated. After that, the sheets were sequentially immersed in multiple baths containing cleaning solutions with gradually decreasing concentrations, from an aqueous zinc chloride solution of 23°Be to water without zinc chloride, and a deliquification process was performed to remove the aqueous zinc chloride solution from the vulcanized fiber base paper, followed by drying with hot air and a cylinder dryer, and then a calendaring process, to obtain a vulcanized fiber substrate. The thickness of the vulcanized fiber substrate was 2.0 mm. <Moisture adjustment treatment> The obtained vulcanized fiber substrate was allowed to stand for 24 hours in an atmosphere of 50° C. and 80% humidity to obtain a vulcanized fiber substrate with a moisture content of 16%. <Mold press processing> The moisture-adjusted vulcanized fiber substrate was molded in a mold measuring 40 cm long x 40 cm wide x 5 cm deep under conditions of a mold temperature of 140°C and a load of 100 t, with pressure applied for 60 seconds and released for 15 seconds, repeated five times each. The moisture content of the resulting vulcanized fiber was 10%.

[0036] Example 2 A vulcanized fiber was obtained in the same manner as in Example 1, except that the moisture content of the vulcanized fiber substrate was changed from 16% to 10% by adjusting the temperature and humidity conditions in the moisture adjustment treatment. The moisture content of the obtained vulcanized fiber was 9.0%.

[0037] Example 3 A vulcanized fiber was obtained in the same manner as in Example 1, except that the moisture content of the vulcanized fiber substrate was changed from 16% to 18% by adjusting the temperature and humidity conditions in the moisture adjustment treatment. The moisture content of the obtained vulcanized fiber was 11.0%.

[0038] Example 4 A vulcanized fiber was obtained in the same manner as in Example 1, except that the temperature and humidity conditions in the moisture adjustment treatment were changed from 16% to 12%. The moisture content of the obtained vulcanized fiber was 9.5%.

[0039] Example 5 A vulcanized fiber was obtained in the same manner as in Example 1, except that the moisture content of the vulcanized fiber substrate was changed from 16% to 17% by adjusting the temperature and humidity conditions in the moisture adjustment treatment. The moisture content of the obtained vulcanized fiber was 10.5%.

[0040] Example 6 A vulcanized fiber was obtained in the same manner as in Example 1, except that the moisture content of the vulcanized fiber substrate was changed from 16% to 14% by adjusting the temperature and humidity conditions in the moisture adjustment treatment. The moisture content of the obtained vulcanized fiber was 10.0%.

[0041] Example 7 A vulcanized fiber was obtained in the same manner as in Example 1, except that the moisture content of the vulcanized fiber substrate was changed from 16% to 9% by adjusting the temperature and humidity conditions in the moisture adjustment treatment. The moisture content of the obtained vulcanized fiber was 9.0%.

[0042] Example 8 A vulcanized fiber was obtained in the same manner as in Example 1, except that the moisture content of the vulcanized fiber substrate was changed from 16% to 20% by adjusting the temperature and humidity conditions in the moisture adjustment treatment. The moisture content of the obtained vulcanized fiber was 11.0%.

[0043] Example 9 A vulcanized fiber was obtained in the same manner as in Example 1, except that the number of times of pressing and releasing in the mold press treatment was changed from 5 times to 1 time. The moisture content of the obtained vulcanized fiber was 12.0%.

[0044] Example 10 A vulcanized fiber was obtained in the same manner as in Example 1, except that the number of times of pressing and releasing in the mold pressing treatment was changed from 5 times to 3 times. The moisture content of the obtained vulcanized fiber was 11.5%.

[0045] Example 11 A vulcanized fiber was obtained in the same manner as in Example 1, except that the number of times of pressing and releasing in the mold pressing treatment was changed from 5 to 10. The moisture content of the obtained vulcanized fiber was 8.5%.

[0046] Comparative Example 1 Except for not heating the mold in the mold pressing step, a vulcanized fiber was obtained in the same manner as in Example 1. The moisture content of the obtained vulcanized fiber was 15.0%.

[0047] Comparative Example 2 A vulcanized fiber was obtained in the same manner as in Example 1, except that the number of base paper sheets was changed from 14 to 6 and the thickness of the vulcanized fiber substrate was changed from 2.0 mm to 0.7 mm when the vulcanized fiber substrate was produced. The moisture content of the obtained vulcanized fiber was 6.0%.

[0048] The evaluation results for the vulcanized fibers obtained in each of the Examples and Comparative Examples are shown in Figure 2. The measurements and evaluations of the values ​​shown in the figure were carried out by the following methods.

[0049] <Thickness> The thickness of the vulcanized fiber was measured in accordance with JIS P 8118:14 Paper and paperboard-Test methods for thickness, density and specific volume.

[0050] <Moisture> The moisture content of the vulcanized fiber was measured in accordance with JIS P 8124:10 Paper, paperboard and pulp - Determination of absolute dryness - Dryer method.

[0051] <Evaluation after die pressing> After pressing in the mold and conditioning at 23°C and 50%, the vulcanized fiber was evaluated for the degree of tearing, wrinkling, and distortion in its appearance. An example of the appearance of vulcanized fiber is shown in Figure 3. Figure 3(a) shows an example of the appearance of a good vulcanized fiber 1 with no tears, wrinkles, or distortion, Figure 3(b) shows an example of the appearance of vulcanized fiber 1 with a tear 2 in part of it, and Figure 3(c) shows an example of the appearance of vulcanized fiber 1 with a wrinkle 3 in part of it. ◎ No issues at all with any of the items being checked. 〇 No issues were identified for each item. △ Each item was checked to some extent, but it is within the range that can be used. (Lower limit of practical use) × Defects were found in each item and it cannot be used. (Not practical)

[0052] As is clear from the results shown in Fig. 2, all of the vulcanized fibers obtained in Examples 1 to 11 were excellent in processability, and no defects in appearance were observed, or even if defects were observed, they were suitable for practical use. In contrast, the vulcanized fiber obtained in Comparative Example 1 was not heated during mold processing, so the moisture in the paper could not be sufficiently removed, resulting in large distortion and lack of practical use. Moreover, the vulcanized fiber obtained in Comparative Example 2 was not able to withstand shrinkage in the surface direction during mold press processing, probably because of insufficient thickness, and was therefore significantly wrinkled, resulting in lack of practical use.

Claims

1. a base paper preparation step of preparing a vulcanized fiber base paper; a gelatinization step of immersing the vulcanized fiber base paper in a reactive chemical to swell and gelatinize the surface of the vulcanized fiber base paper; a deliquation step of immersing the vulcanized fiber base paper in a solution having a lower concentration than the reactive chemicals to remove the reactive chemicals; a drying step of drying the vulcanized fiber base paper after the deliquor to obtain a vulcanized fiber substrate; a moisture adjusting step of adjusting the moisture of the vulcanized fiber substrate; a mold pressing step in which the moisture-adjusted vulcanized fiber substrate is subjected to a mold pressing treatment using a mold heated to 90 to 180° C. to obtain a vulcanized fiber; In the die pressing step, pressure is applied and released at least once, A method for processing vulcanized fibers, characterized in that the thickness of the vulcanized fiber substrate is 0.8 mm or more.

2. 2. The method for processing vulcanized fiber according to claim 1, wherein the moisture content of the moisture-adjusted vulcanized fiber substrate is 10 to 18%.

3. a base paper preparation step of preparing a vulcanized fiber base paper; a gelatinization step of immersing the vulcanized fiber base paper in a reactive chemical to swell and gelatinize the surface of the vulcanized fiber base paper; a deliquation step of immersing the vulcanized fiber base paper in a solution having a lower concentration than the reactive chemicals to remove the reactive chemicals; a drying step of drying the vulcanized fiber base paper after the dewatering to obtain a vulcanized fiber substrate having a moisture content of 10 to 18%; a mold pressing step in which the moisture-adjusted vulcanized fiber substrate is subjected to a mold pressing treatment using a mold heated to 90 to 180° C. to obtain a vulcanized fiber; In the die pressing step, pressure is applied and released at least once, A method for processing vulcanized fibers, characterized in that the thickness of the vulcanized fiber substrate is 0.8 mm or more.

4. 4. The method for processing vulcanized fiber according to claim 1 or 3, wherein the die used in the die pressing step is a drawing die.

5. 4. The method for processing vulcanized fiber according to claim 1, wherein the number of times of pressing and releasing carried out in the mold pressing step is 1 to 10 times. [Request 6] The density of the vulcanized fiber substrate is 1.20 to 1.35 g / cm 3 4. The method for processing vulcanized fiber according to claim 1 or 3, characterized in that

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