KR20030048259A - Method for producing cellulosic fibers by means of Cold-pad-batch - Google Patents

Abstract

PURPOSE: A manufacturing method of cellulose fiber by a cold-pad-batch method is characterized by having a simple manufacturing process and reducing the production cost. The cellulose fiber has properties like existing cellulose fiber. CONSTITUTION: The cellulose fiber is obtained by a process containing the steps of: preparing fiber or fiber products containing cellulose diacetate(45-59.5% of acetification or 2.0-2.75 of substitution); substituting at least 75% of acetyl group in cellulose acetate fiber to a hydroxyl group by the cold-pad-batch method in the presence of a surfactant; and then converting into the cellulose fiber.

Description

Method for producing cellulosic fibers by cold pad batch method {Method for producing cellulosic fibers by means of Cold-pad-batch}

The present invention relates to a method for producing cellulose fibers from cellulose acetate by a cold pad-batch method.

Conventionally, an alkali treatment method for producing cellulose fibers from cellulose acetate has a batch method in which a certain amount of fabric is added and treated in a liquid dyeing machine.

However, the discontinuous liquid batch method as described above has a long reaction time for converting cellulose acetate into cellulose fibers and a limited input amount per batch, resulting in an increase in manufacturing cost.

In addition, a conventional alkali treatment method includes a continuous alkali treatment method using a continuous reducer. This method is mainly used for weight loss of polyester fabrics, requiring high temperature and high alkalinity conditions. The production of cellulose fibers from cellulose acetate using a continuous reducer used to reduce polyester fabrics is not suitable for producing good quality cellulose fibers because they do not result in uniform reactions.

It is therefore an object of the present invention to provide a new method for producing cellulose fibers from cellulose acetate by cold-pad-batch method at low temperature conditions without the problems of the prior art as described above.

According to the present invention to achieve the above object is a cold pad batch (Cold) in the presence of a surfactant at a low temperature to a fiber or textile product containing at least a portion of cellulose diacetate of degree of substitution 2.0 to 2.75 (45-59.5% superoxide) Alkali treatment by -pad-batch) provides a method for producing cellulose fibers, comprising the step of converting at least 75% of the total acetyl groups of the cellulose acetate fibers to hydroxy groups to convert to cellulose fibers.

Hereinafter, the present invention will be described in more detail.

Alkali treatment of cellulose diacetate results in saponification in which acetyl groups are converted to hydroxy groups. Crystallization occurs due to rearrangement of folding and packing of molecular chains of diacetate fibers that were amorphous. In general, natural cellulose has a crystalline structure of cellulose I. In the case of regenerated cellulose fibers, cellulose II has a structure of cellulose, whereas cellulose fibers prepared by saponification of cellulose diacetate have a crystal structure of cellulose II and VI. Crystallinity (specific gravity method) 14-34%, birefringence 0.012 ~ 0.024.

The cellulose fiber obtained by saponification of a cellulose diacetate fiber is also a kind of rayon fiber. The physical properties of these cellulose fibers are 1.48 ~ 1.51gm / cm ³ , tensile strength 1.2 ~ 2.5gf / de, elongation 20 ~ 50%, standard moisture content 12 ~ 13%.

Examples of alkali compounds that can be used in the saponification process include alkali metal hydroxides such as sodium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, alkali metal carbonates such as sodium carbonate, and the like.

The present invention is characterized in that a surfactant is used during the alkali treatment, because the surfactant facilitates the internal penetration of the alkali so that a uniform reaction occurs and the strength of the fiber is prevented from being lowered. The surfactant is not particularly limited, and polyethylene glycol type nonionic surfactants, polyhydric alcohol type nonionic surfactants and anionic surfactants are particularly preferable, and the amount of the surfactant added must be 0.5 g / L or more, but the effect is not achieved. It is expressed, there is no difference in effect at 0.5 g / L or more, and more preferably 1 g / L.

In the present invention, a fiber or a textile product containing at least a part of cellulose diacetate having a degree of substitution of 2.0 to 2.75 is used as a raw material for producing cellulose fibers.

In addition, the present invention is characterized in that in the conversion of cellulose fibers from the fibers as described above, including a step of alkali treatment by cold-pad-batch (Cold-pad-batch) method at a low temperature, the reaction conditions and process An example is as follows.

Prepare 20-53% aqueous alkali solution in the padding tank of the cold-pad-batch reducer, and immerse the fiber or textile product containing some refined dried cellulose diacetate fibers in the prepared aqueous alkali solution. ~ 100% Wet Pick-up. The wet-picked fibers are wound on a storage roll, and the wound fibers are treated at 20 ^° C. or higher and 70 ^° C. or lower for 1 to 48 hours and washed with water to prepare cellulose fibers.

The concentration of the aqueous alkali solution is preferably in the range of 20 to 53%, but the reaction is slow at less than 20%, and the reaction does not occur completely. When the concentration is higher than 53%, the aqueous alkali solution becomes saturated with sodium hydroxide (NaOH). This is because it is impossible to manufacture.

Further, according to an alkali treatment in the process of the present invention the alkaline processing temperature together is 20 ^o or more C 70 ^o C or less preferably, 20 ^o C less than the and the reaction is insufficient, 70 ^o, if it exceeds the C is non-uniform reaction, and the molecular chain Cleavage will occur which makes it unsuitable for the present invention.

Features and other advantages of the present invention as described above will become more apparent from the following examples. However, the present invention is not limited to the following examples.

In the following examples, the loss ratio and other physical properties of cellulose acetate are measured by the following method.

Deacetylation: Deacetylation was confirmed by infrared spectroscopy using an infrared spectrometer (MAGNA 750, Nicolet, USA). At this time, deacetylation was confirmed by the presence or absence of the carbonyl band of the acetyl group which appears at 1760 cm <^-1> .

* Reduction rate: The weight change of the sample before and after alkali treatment was measured and obtained by the following equation.

(Sample weight before treatment-sample weight after treatment)

Reduction ratio (%) = ----------------------------------- × 100

(Sample weight before treatment)

* Cutting strength and elongation of fiber: Measured by using a universal testing machine (Universal Testing Machine: ZWICK 1425, Germany) to tensile length of 50mm, tensile speed 200m / min.

* Dyeing property: dye direct dye CI Direct Blue 200 (Kayaarus Supra Blue 4BL) with 0.5% owf concentration at 100 ℃ for 30 minutes, and then soap and rinse at 70 ℃ Staining was completed. Measure the reflectance (R: Reflectance) by using a spectrophotometer (Color-Eye 7000A, Machbeth, USA), and substitute this into the equation K / S = (1-R) ² / 2R to determine the K / S value. Was obtained and the dyeability was evaluated using this value.

Example 1

Cold pad after scouring and drying plain fabric (incline 75d / 20f, weft 120d / 33f, stomach density 75 / inch, SK chemical acid, Korea) composed of cellulose diacetate fibers with acetyl substitution degree 2.55 (56.9% superoxide) Caustic soda was added to a 53% solution of caustic soda in a padding tank of a cold-pad-batch reducer and dissolved, followed by dissolving 1 g / L of a surfactant. The prepared cellulose diacetate scouring paper was immersed in alkali treatment so that the wet pick-up of the caustic soda solution was 70%. Alkali-treated cellulose diacetate was wound in a storage roll and then saponified at 20 ^° C. for 24 hours. The saponified fiber was washed in a water bath to remove residual alkali and to dry the fiber. Through this saponification process, a cellulose fiber having a weight loss ratio of 40% relative to the initial cellulose diacetate fiber weight was obtained.

Infrared spectroscopy analysis of the raw fiber and the fiber reduced by saponification showed that the diacetate fiber used as the raw material showed a large carbonyl band of acetyl group near 1760 cm ^-1 , while the loss ratio was 40 in Example 1. % of cellulose fibers, it was found that all of the acetyl group is substituted with a hydroxy group to a carbonyl band completely disappears and increase the stretching of the hydroxyl groups 3400cm ^-1 (hydroxy stretching) in the vicinity of 1760cm ^-1.

The measurement results of the physical properties of the fibers obtained in the above examples are shown in Table 1.

Example 2

Except that the caustic soda solution was used at 25%, the caustic soda solution was 100% wet pick-up of cellulose diacetate, and the temperature during alkali treatment was 70 ° C. The same procedure as in 1 was repeated.

Through the saponification process of the above embodiment, a cellulose fiber having a weight loss ratio of 39.5% based on the weight of the initial cellulose diacetate fiber was obtained.

Infrared spectral analysis as in Example 1, it was found that the acetyl group is completely substituted with a hydroxyl group.

The measurement results of the physical properties of the fibers obtained in Example 2 are also shown in Table 1.

Comparative Example 1

Liquid dyeing machine after scouring and drying plain fabrics (inclined 75d / 20f, weft 120d / 33f, gas density 75 / inch, SK chemicals, 韓國) composed of cellulose diacetate fibers with acetyl substitution degree 2.55 (56.9% superoxide) Water was added 15 times the weight of diacetate fiber and caustic soda was added to make a 40% aqueous solution of caustic soda.

The prepared diacetate fiber scouring paper was added to a liquid dyeing machine, and then heated to 30 ^° C. at 2 ^° C / min, treated at 98 ^° C. for 30 minutes, cooled to 30 ^° C. at 2 ^° C / min, and drained. Water was added at room temperature and washed with water to remove residual alkali and dried the fibers. Through this saponification process, a fiber having a loss ratio of 40% relative to the initial diacetate fiber weight was obtained.

As in Example 1, it was confirmed that the acetyl group was completely substituted with a hydroxy group through infrared spectroscopic analysis.

In addition, as shown in Table 1, it can be confirmed that the physical properties and dyeing properties of the cellulose fibers prepared by the cold-pad-batch method at a low temperature exhibit almost similar properties to those of the cellulose fibers prepared in the liquid of Comparative Example 1. there was.

division Example 1 Example 2 Comparative Example 3 Caustic Sodium Concentration (ows,%) 53 25 2.7 Treatment temperature (℃) 20 70 98 Acetate loss rate (%) 40 39.5 40 Fineness (De) 91.1 90.9 91.2 Cutting strength (gf / de) 1.42 1.43 1.34 Elongation at break (%) 42.5 43.0 42.0 Dyeability (K / S) 9.51 9.42 8.47

As will be apparent from the above experimental results, the cellulose fibers prepared by the cold-pad-batch method at low temperature from the cellulose diacetate fibers according to the present invention are chemical structures and physical properties of the conventional viscose rayon fibers. This is similar, and has similar characteristics to cellulose fibers produced by liquid treatment at high temperature, and thus can be applied to the same use, and also by a cold-pad batch process at low temperature, a simple manufacturing process It has the advantage of being able to manufacture at low manufacturing cost and safe operating conditions.

Claims (4)

Degree of substitution 2.0-2.75 (45-59.5% superoxidation degree) Alkali treatment by the cold-pad-batch method of the fiber or textile product containing at least a part of cellulose diacetate at low temperature in the presence of a surfactant A method for producing a cellulose fiber by the cold-pad-batch method, comprising the step of converting at least 75% of the total acetyl groups of the cellulose acetate fibers into hydroxy groups to convert to cellulose fibers. The method of claim 1, wherein the alkali compound used in the alkali treatment is an alkali metal hydroxide, alkaline earth metal hydroxide, alkali metal carbonate production of cellulose fibers by the cold-pad batch method characterized in that Way. The method of claim 1, wherein the surfactant is a polyethylene glycol type nonionic surfactant, a polyhydric alcohol type nonionic surfactant, an anionic surfactant, characterized in that the cellulose fiber by the cold-pad-batch method Manufacturing method. 2. The cold-pad batch method according to claim 1, wherein the alkali treatment concentration is 20 to 53%, a treatment temperature of 20 to 70 ^° C., and a treatment time of 1 to 48 hours. The manufacturing method of cellulose fiber by