JP2009052159A - Method for heat-treating cellulosic material or molded article thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for heat-treating a cellulosic material or a molded article thereof to stabilize the shape by using a continuous heat-treating method capable of carrying out the treatment at a normal pressure without using a chemical, and capable of carrying out excellent shape-stabilizing treatment of the cellulose. <P>SOLUTION: The method for heat-treating the cellulosic material or the molded article thereof uses superheated steam in the heat-treating step of the cellulosic material or the molded article thereof. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for imparting shape stability of a cellulosic material or a molded body thereof.

Cellulose-based materials or molded articles thereof are generally poor in form stability and easily contract by moisture absorption treatment and drying treatment. In particular, fabrics made of cellulosic fibers have the disadvantage that they are poor in form stability, are more likely to wrinkle as washing is repeated, and those that have been subjected to pleating are easily lost by washing.
As a method for improving these problems, Patent Document 1 proposes a heat treatment method using high-temperature and high-pressure steam treatment in order to impart improvement in form stability. However, since this method requires high-pressure treatment with an absolute pressure of 4 kgf / cm ² or more, batch-type treatment using a high-pressure vessel is the center, production efficiency is low, and there is a method of continuously heat-treating with high efficiency. It has been demanded. Furthermore, since high-pressure processing using a high-pressure vessel is required, expensive equipment and advanced operation management are required. Cellulose morphology stabilization treatment includes a resin processing method and a drug method using a drug such as formalin. However, problems such as a decrease in strength, a decrease in texture, and a drug residue are likely to occur.

Furthermore, for example, when heat treatment of cellulosic fibers is taken as an example, it is necessary to heat the cellulosic fibers once in a temporary winding state such as cheese or corn, and for that purpose, uniform to the inner and outer layers of cheese or corn or the like. There was a problem that heat treatment was difficult to obtain, and quality problems such as a difference in form-stable inner and outer layers and a difference in dyeing were likely to occur.
Patent Document 2 discloses a continuous dyeing processing method and apparatus for fabric using superheated steam, but it is proposed to use superheated steam for the purpose of fixing the dye to the fabric in the dyeing process. However, it is not intended to stabilize the morphology of the cellulose material.
From such a point of view, in the heat treatment method aimed at stabilizing the morphology of the cellulosic material or molded article thereof, it can be treated at normal pressure without using a chemical, and further, by using a continuous heat treatment method, There is a demand for a method capable of achieving excellent shape stabilization processing.

JP 2001-16459 A JP 2007-9353 A

  An object of the present invention is to solve the above-mentioned conventional problems and to provide a method for continuously heat-treating at a normal pressure in order to impart improvement in shape stability to a cellulosic material or a molded product thereof.

In order to solve the above-mentioned problems, the present inventors have found a heat treatment method using superheated steam in order to impart the form stability of the cellulosic material or its molded product, and this method can be used at normal pressure as a heat source. The heat treatment method of the present invention that can be continuously heat treated has been completed.
That is, the present invention is as follows.
(1) A heat treatment method using superheated steam in a heat treatment step of a cellulosic material or a molded body thereof.
(2) The heat treatment method according to (1) above, wherein the temperature of the superheated steam is 130 to 250 ° C.
(3) The heat treatment method according to (1) above, wherein the temperature of the superheated steam is 170 to 200 ° C.
(4) The heat treatment method according to any one of the above (1) to (3), wherein the cellulose-based material or the molded body thereof has a cellulose mixing ratio of 40% by weight or more.
(5) In any one of the above (1) to (4), the method includes a step of adjusting the moisture content of the cellulosic material or molded body thereof before the heat treatment step of the cellulosic material or molded body thereof. The heat treatment method as described.

(6) The heat treatment method according to (5) above, wherein in the step of adjusting the moisture content, the moisture content is 5% by weight or more.
(7) The method according to any one of (1) to (6) above, wherein the method comprises a superheated steam generation step and a heat treatment step using the superheated steam as a heat source, and the heat treatment is performed in a batch mode under normal pressure. Heat treatment method.
(8) The method according to any one of (1) to (6), wherein the method includes a superheated steam generation step and a heat treatment step using the superheated steam as a heat source, and the heat treatment is continuously performed under normal pressure. Heat treatment method.
(9) The cellulosic material is any one of (1) to (8) above, wherein the cellulosic material is a fibrous material, a film material, a particulate material, a porous material, or a hollow fiber material. Heat treatment method.
(10) The heat treatment method according to any one of (1) to (8), wherein the molded body is a woven fabric, a knitted fabric, a nonwoven fabric, or a composite thereof.
(11) The heat treatment method according to any one of (1) to (10), wherein the superheated steam is in a state not containing air.

By using the heat treatment method with superheated steam according to the present invention, excellent shape stability of the cellulosic material or the molded product thereof can be obtained, and the following effects are also obtained.
(1) Since superheated steam is used as a heat source, a continuous heat treatment method can be performed at normal pressure.
(2) Heat treatment with inexpensive normal pressure equipment is possible without using expensive high-pressure vessel equipment or the like.
(3) In particular, in the case of cellulosic fibers, since the fiber material can be heat-treated in a fibrous form as it is without being temporarily wound into a cheese, corn, or the like, it is possible to impart uniform shape-stabilization.
Further, the cell-based fiber whose form has been stabilized can be mixed with dissimilar fibers such as synthetic fibers such as nylon and polyester that are weak against heat, and a mixed product with high form-stabilization can be easily obtained.
(4) When the heat treatment of the present invention is applied to the cellulosic fiber, it becomes possible to obtain a fiber having excellent shrinkage performance with a hot water shrinkage of 3% or less.
(5) Heat treatment can be performed in an atmosphere close to an oxygen-free state in which almost no air is contained in the superheated steam, thereby enabling treatment with suppressed oxidation.

A feature of the present invention is a processing method characterized in that in a heat treatment step of a cellulosic material or a molded product thereof, superheated steam is used for continuous heat treatment at normal pressure. By using this method, excellent shape stability of the cellulosic material or a molded body thereof can be obtained.
In the present invention, the cellulose material refers to natural cellulose materials such as cotton and hemp, regenerated cellulose materials such as copper ammonia rayon, viscose rayon and polynosic, and purified cellulose materials such as tencel. The regenerated cellulose material has a lower crystallinity than the natural cellulose material, has a structurally weak denseness, and is easy to achieve the effect of the superheated steam treatment, which is a preferable embodiment.

In each material, the cellulose content is preferably 40 wt% or more, more preferably 60%.
wt% or more, particularly preferably 80 wt% or more. The shape is preferably a fibrous material, a film-like material, a particulate material, a porous material, or a hollow fiber material, more preferably a fibrous material, a film-like material, or a particulate material.
The cellulosic material of the present invention is excellent in form stability, and when mixed with a thermoplastic synthetic fiber material or the like, the form stability of the whole material is further improved, which is preferable.
Examples of cellulose fibrous materials include multifilament yarns, spun yarns, and monofilaments, and the fineness is preferably in the range of 20 to 200 dtex, more preferably 30 to 150 dtex. The single yarn fineness is preferably 0.5 to 3 dtex / f, more preferably 1.0 to 2.0 dtex / f.

The molded article of the cellulose material of the present invention is preferably a woven fabric, a knitted fabric, a nonwoven fabric, or a composite thereof composed of the cellulose-based material. In particular, a woven fabric, a knitted fabric, a nonwoven fabric, or a composite thereof composed of cellulosic fibers is preferable, and a molded body composed of regenerated cellulose fibers is more preferable.
The molded article of the cellulosic material of the present invention includes a woven fabric, a knitted fabric, a nonwoven fabric, or a composite thereof obtained by mixing cellulosic materials, and a woven fabric, a knitted fabric, a nonwoven fabric, or a mixture of a cellulosic material and a different material. These composites are also included. In each molded article, the cellulose content is preferably 40 wt% or more, more preferably 60 wt% or more, and particularly preferably 80 wt% or more.
For example, composites of cellulosic fibers and synthetic fibers in woven fabrics, composites of cellulose-based films and dissimilar materials in films, and composites of dissimilar materials with cellulose-based particles or chips in particles and chips Is mentioned.

The superheated steam used in the present invention is a gas obtained by further heating saturated dry steam at normal pressure, and is preferably a gas containing water as a main component and containing almost no air and in an oxygen-free state. Therefore, there is almost no oxygen in the superheated steam, and there is an effect of suppressing oxidation in the thermal processing using this as a heat source.
When the cellulosic material is steam-treated in a high-pressure state, the cellulose itself is easily oxidized, and the hydroxyl group is oxidized, and the oxidized functional group tends to increase or the color changes to yellow. This tendency is particularly strong in regenerated cellulose having low crystallinity, and this yellowing phenomenon in the sterilization treatment with high-pressure steam is caused by this oxidation. In the heat treatment with superheated steam of the present invention, such oxidative degradation of cellulose can be prevented, and an excellent shape stabilizing effect is obtained.

FIG. 1 shows an installation example of a superheated steam apparatus in the heat treatment step of the present invention.
In the present invention, it has a superheated steam generation step and a heat treatment step using the superheated steam as a heat source, and it can be heat-treated in a batch type or a continuous type under normal pressure. This is a more preferred embodiment from the viewpoint of efficient production.
As shown in FIG. 1, when heat treatment is performed using superheated steam, it is preferable to provide a dehydration part or a water injection part for adjusting the moisture content before the heat treatment process, and it is more preferable to provide moisture in the case of continuous heat treatment. The installation position of the superheated steam generator is appropriately set depending on the object to be heat-treated, and can be determined in the upstream part, the downstream part, or the intermediate part of the heat treatment process.
In order to improve the shape stability of the cellulosic material or molded product thereof, the moisture content of the cellulosic material or molded product before heat treatment, the treatment temperature of superheated steam, and the treatment time are important factors.

In the present invention described below, the moisture application rate before the heat treatment of the cellulosic material or the molded body thereof, it is preferable to give 5% by weight or more of moisture to the object in advance before the heat treatment, more preferably. 50 to 90% by weight of moisture.
In order to control the above-described predetermined moisture content, the moisture content of the cellulosic material to which moisture is excessively added or the molded body thereof may be adjusted by centrifugal dehydration, press dehydration, etc. Alternatively, predetermined moisture may be applied after drying.
As shown in Table 1 in the examples described later, when the moisture content was changed from 5% by weight to 70% by weight in the comparison between Example 2 and Example 6, the wet stretch ratio (morphological stability in the yarn length direction) Evaluation) is -1.5% in Comparative Example 1, -1.1% in Example 2, and -0.8% in Example 6, and the form stability is good under the condition of increasing moisture. It has the effect of becoming. The same effect can be said from the comparison between Example 1 and Example 5.

Next, the processing temperature of superheated steam and its effect will be described.
The processing temperature of superheated steam in the present invention is 101 ° C or higher, preferably 130 ° C to 250 ° C, more preferably 170 ° C to 200 ° C.
As shown in Table 1 in Examples described later, in the comparison between Example 5 and Example 6, when the treatment temperature was changed from 130 ° C. to 170 ° C. under the condition of the heat treatment time of 30 minutes, the wet expansion and contraction was compared with that in Comparative Example 1. The rate (form stability evaluation in the yarn length direction) was -1.5% in Comparative Example 1, -1.0% in Example 5, and -0.8% in Example 6, and the temperature was increased. It can be said that the case has better shape stability. In the comparison between Example 10 and Example 11 in Table 2, when the processing temperature is changed from 150 ° C. to 170 ° C., the same effect is seen in comparison with Comparative Example 2.

Next, the effect of the treatment time of superheated steam will be explained.
The treatment time of superheated steam in the present invention is set to an optimum time in consideration of the treatment temperature, but is usually 1 to 60 minutes, preferably 10 to 30 minutes. In the comparison between Example 3 and Example 4 in Table 1, when the treatment time is changed from 5 minutes to 10 minutes, the wet stretch ratio (form stability evaluation in the yarn length direction) is 1 in comparison with Comparative Example 1, and Comparative Example 1 is -1. 5%, Example 3 is -1.0%, and Example 4 is -0.9%. It can be said that the longer the processing time, the better the form stability. In the comparison between Example 9 and Example 11 in Table 2, when the treatment time was changed from 5 minutes to 20 minutes, the dimensional change C method compared to Comparative Example 2 and Comparative Example 2 was 2.5% (vertically) / 2. .6% (width), Example 9 has a value of 2.0% / 2.0%, and Example 11 has a value of 1.5% / 1.6%, showing a more remarkable effect.
Since the moisture content of these cellulosic materials or their molded products and the treatment temperature and treatment time of superheated steam work in combination, the conditions prior to heat treatment and economics of the cellulosic materials and their molded products are taken into account for each condition. Must be set.

The present invention will be described based on examples, but the present invention is not limited to the following examples. In addition, the measuring method of each characteristic value is as follows.
(1) Hot water shrinkage (form stability evaluation in the yarn length direction)
Take 500 mm of dried cellulose fiber, immerse it in 100 ° C. hot water for 30 minutes, remove excess water, and leave it in a room controlled at 20 ° C. and 65% RH for 24 hours or more. Measure and calculate the hot water shrinkage.
Hot water shrinkage (%) = 100 × ± fiber length difference before and after hot water treatment (mm) / 500 (mm)

(2) Wet stretch rate (form stability evaluation in the yarn length direction)
The dried cellulose fiber is allowed to stand for 16 hours or more in a room whose temperature and humidity are adjusted to 20 ° C. and 65% RH, and then 5 to 6 m is collected. Cellulose fibers are attached to a fixed stretch distance of 1000 mm on a wet stretch rate measuring instrument. A weight of 1 to 7 g is applied to the lower part of the mounting jig so that a certain tension is applied. When the Wet stretch measurement device is started, water droplets are transferred to the yarn for 3 minutes from the top, and the fiber length when wet is measured to calculate the Wet stretch rate.
Wet stretch rate (%) = 100 × ± stretched length (mm) / 1000 (mm)
(3) Single yarn diameter swelling degree (Evaluation of form stability in the single yarn diameter direction)
The dried cellulose fibers and aggregates thereof are left in a room whose temperature and humidity are adjusted to 20 ° C. and 65% RH for 16 hours or more, and then the fiber length of several mm is cut out and the fiber diameter is measured with a microscope. Furthermore, after adding excess water and moistening, the fiber diameter is measured with a microscope, and the single yarn diameter swelling degree is calculated. Single yarn diameter swelling degree = fiber diameter after water application / fiber diameter before water application

[Examples 1-7]
Using the treatment time and treatment temperature of superheated steam and 100% cupra fiber (brand name FB84dtex, manufactured by Asahi Kasei Fibers) (total fineness 84dtex, single yarn fineness 1.87dtex), the moisture content before treatment was set to Examples 1 to 6. Then, heat treatment using superheated steam was performed, and the morphological stability after the superheated steam treatment was evaluated.
In addition, the form stability of the air mixed yarn type composite fiber composed of the blend ratio of 48 wt% cupra fiber / 52 wt% ester fiber in Example 7 was also evaluated. The evaluation results are shown in Table 1.
As shown in Table 1, in Comparative Example 1 and Example 6, the hot water shrinkage rate was 3.6% to 2.2%, the wet stretch rate was -1.5% to -0.8%, and the single yarn diameter Morphological stability improved from a swelling degree of 1.4 to 1.2.
[Comparative Example 1]
In Examples 1 to 6, 100% cupra fiber (brand name: FB84 dtex, manufactured by Asahi Kasei Fibers Co., Ltd.) (total fineness: 84 dtex, single yarn fineness: 1.87 dtex) before performing heat treatment with superheated steam. It was shown to.

[Examples 8 to 11]
Treatment conditions of superheated steam and fabric of 100% cupra fibers (warp yarn FB84 dtex: 126 yarns / 吋, weft yarn FB84 dtex: 90 yarns / 吋 plain weave structure) JIS standard general textile testing method (JIS-L-1096) The morphological stability of the fabric was evaluated using the dimensional change C method (vertical shrinkage%). The evaluation results are shown in Table 2.
As shown in Table 2, in Comparative Example 2 and Example 11, the dimensional change C method improved the shrinkage from 2.5% to 1.5%, and from 2.6% to 1.6%. The shrinkage rate improved, and the morphological stability of the vertical was improved.
[Comparative Example 2]
In Examples 8 to 11, a fabric of 100% cupra fibers before performing heat treatment with superheated steam (a warp yarn FB84 dtex: 126 yarns / 吋, a weft yarn FB84 dtex: 90 yarns / 吋 plain weave structure) was evaluated. The evaluation results are shown in Table 2.

  The treatment method of the present invention can be treated at normal pressure without using a chemical, and can be continuously heat-treated with high efficiency, and has an excellent effect on improving the form stability of the cellulosic material or its molded body. Is.

Installation example of superheated steam equipment in heat treatment process

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Boiler 2 ... Superheated steam generator 3 ... Raw material 4 ... Water provision process 5 ... Press dehydration process 6 for moisture content adjustment 6 ... Superheated steam jet nozzle 7 ...・ Multi-stage roller heat treatment process 8 ... winding process

Claims (11)

  A heat treatment method characterized by using superheated steam in a heat treatment step of a cellulosic material or a molded product thereof.   The heat treatment method according to claim 1, wherein the temperature of the superheated steam is 130 to 250 ° C.   The temperature of the said superheated steam is 170-200 degreeC, The heat processing method of Claim 1 characterized by the above-mentioned.   The heat treatment method according to any one of claims 1 to 3, wherein a mixing ratio of cellulose is 40% by weight or more in the cellulosic material or a molded body thereof.   The heat treatment method according to any one of claims 1 to 4, further comprising a step of adjusting a moisture content of the cellulosic material or the molded body thereof before the heat treatment step of the cellulosic material or the molded body thereof.   6. The heat treatment method according to claim 5, wherein in the step of adjusting the moisture content, the moisture content is 5% by weight or more.   The heat treatment method according to any one of claims 1 to 6, comprising a superheated steam generation step and a heat treatment step using the superheated steam as a heat source, and performing the heat treatment in a batch mode under normal pressure.   The heat treatment method according to any one of claims 1 to 6, further comprising a superheated steam generation step and a heat treatment step using the superheated steam as a heat source, and performing the heat treatment continuously under normal pressure.   The heat treatment method according to claim 1, wherein the cellulosic material is a fibrous material, a film-like material, a particulate material, a porous material, or a hollow fiber material.   The heat treatment method according to claim 1, wherein the molded body is a woven fabric, a knitted fabric, a nonwoven fabric, or a composite thereof.   The heat treatment method according to claim 1, wherein the superheated steam does not contain air.

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