KR100531932B1 - Heat-resistant breakthrough cellulose acetate moldings and preparation method thereof - Google Patents

Abstract

The present invention relates to a heat-resistant cellulose acetate molded article and a method for producing the same, and more particularly, to a method for producing a cellulose acetate molded article from cellulose acetate flakes, wherein the cellulose acetate flakes are dissolved in acetone and water to prepare a dope composition. Next, a method for preparing a heat-resistant cellulose acetate molding by adding 3 to 20% by weight of a halogenated compound of Zn, Sn or Co metal to acetate flakes, and a molding produced by the above method. The acetate fibers, films, and sheets thus prepared exhibit excellent heat devitrification resistance and mechanical properties even under alkaline, acidic and neutral hydrothermal treatment at a high temperature and high pressure of 90 to 140 캜, and dry heat treatment up to 200 캜.

Description

Heat-resistant breakthrough cellulose acetate moldings and preparation method thereof

The present invention relates to a heat-resistant cellulose acetate molded article and a method for producing the same, and more particularly, to a cellulose acetate molded article and a method for producing the same, which are not devitrified when subjected to wet heat and dry heat treatment.

Ordinary cellulose acetate (hereinafter referred to as "acetate") fibers or films are treated with hot water of 90 ° C. or higher or dry heat of 170 ° C. or higher to lose transparency. These devitrification phenomena are accompanied by deterioration of various physical properties of acetate, such as touch, gloss, sharpness, softness, etc., or glossiness may occur. In addition, in the case of dyeing the acetate fibers at 90 ° C. or lower, if a carrier is not added, black or dark red deep color is hardly obtained, and the leveling time for obtaining proper fastness is relatively long.

On the other hand, when the dyeing temperature of the acetate fiber to 100 ℃ or more, it is possible to shorten the dyeing time can reduce the production cost. In addition, when manufacturing a fiber product that is mixed with the acetate and the fiber to be dyed at high temperature and high pressure, such as polyester, the quality, such as touch, gloss, sharpness of the dye, softness is greatly changed depending on the devitrification resistance of the acetate. Accordingly, there has been a demand for acetates that do not lose their physical properties even after high temperature dyeing at 100 ° C or higher and dry heat treatment at 180 ° C or higher.

The devitrification of acetate occurs more severely with higher heat treatment temperature and longer treatment time. In order to improve the devitrification by this heat treatment, various methods have been proposed so far.

In Japanese Patent Application Laid-Open No. 47-2052, a dope was prepared at an acetate flake concentration of 18% by weight or less, and then acetone, a solvent, was adjusted to 20% by weight or more, and water was added to 4% by weight or less. A method of making dope and spinning to produce acetate fibers with improved devitrification resistance is disclosed. However, the method of producing the devitrification-resistant acetate fibers with the above patent has two disadvantages. First, the hot water treatment temperature is somewhat effective to improve the devitrification resistance at 100 ℃, but is not effective at improving the devitrification resistance at 120 ℃, and second, after preparing the acetate concentration of the initial dope to 15% by weight or less, the solvent is evaporated In the process of manufacturing more than 24% by weight, the energy and processing time is required to increase the cost.

In Japanese Patent Application Laid-Open No. 48-11762, dicarboxylic acid or an ester derivative thereof is added to 0.05 to 4% by weight of the acetate flakes to prepare acetate dope and spun to obtain a devitrification resistant acetate. As can be seen in the examples of the patent, the acetate fiber produced by this method is slightly impaired when compared to the untreated sample when steamed at 110 ° C. or hydrothermally treated at 98 ° C., thereby not exhibiting perfect devitrification resistance.

In Japanese Patent Application Laid-Open No. 48-13726, cellulose acetate was immersed, stirred, and dehydrated in an aqueous solution of carbonic acid or bicarbonate (metal ion concentration of 5 to 300 ppm) of Ba, Pb, Cs, Sr, or Zn to prepare a devitrification-resistant acetate flake. In Japanese Patent Application No. 49-10609, p-oxybenzoic acid is added to 0.001 to 1% by weight of the weight of acetate flakes to the acetate flakes prepared in Japanese Patent Application No. 48-13726, to prepare dope, and spin-resistant. Acetate fibers were made. However, there are the following drawbacks in the preparation of devitrification-resistant acetates by the methods of Japanese Patent Laid-Open Nos. 49-10609 and 48-13726. First, in the preparation of acetate flakes, a process of adding immersion and stirring to an aqueous metal salt solution is added, and manufacturing cost increases. Second, the hydrothermal treatment of acetate fibers prepared by these methods is slightly devitrified compared to the sample before treatment. Is not perfect. In addition, there has been proposed a method for producing a devitrification resistant acetate fiber using purified acetate flakes in which impurities, cellulose acetate having a low degree of superoxidation, low polymerization degree cellulose acetate, and the like are removed with a solvent. The solvent used at this time includes a mixed solvent of a solvent of acetate and a non-solvent (Japanese Patent Application No. 48-23543), an alkyl alcohol having 5 or less carbon atoms, or an aqueous solution thereof (Japanese Patent Application No. 48-23542). However, the method also increases the manufacturing cost with the trouble of purifying the acetate flakes, and the anti-devitrification effect of the obtained acetate fiber is not perfect as shown in the examples of the above patents.

Accordingly, the inventors of the present invention provide an acetate molding having perfect devitrification resistance in hot water treatment up to 140 ° C. and dry heat treatment up to 200 ° C. while eliminating the disadvantages of preparing the devitrification resistant acetate molding by the conventional method. The devitrification phenomena were identified at the molecular level and polymer morphology. As a result, it was confirmed that the amount of hydroxyl groups not intermolecular and intramolecular hydrogen bonds of acetate (hereinafter referred to as "unbonded hydroxyl groups") is directly related to the devitrification phenomenon. It became.

Accordingly, it is an object of the present invention to provide a method for producing an acetate molding having perfect devitrification resistance in hot water treatment up to 140 ° C and dry heat treatment up to 200 ° C.

Another object of the present invention is to provide a molded article produced by the above method.

The method of the present invention for achieving the above object in the method for producing a cellulose acetate molded article from cellulose acetate flakes, to prepare a dope composition by dissolving cellulose acetate flakes in acetone and water, and then halogen of Zn, Sn or Co metal The compound consists of adding 3-20% by weight relative to acetate flakes.

Looking at the present invention in more detail as follows.

As described above, it was confirmed that the amount of non-bonded hydroxyl groups not intermolecular and intramolecular hydrogen bonds of acetate is directly related to devitrification. In other words, as the amount of unbonded hydroxyl groups increased, the devitrification decreased, and the content of hydrogen-bonded water also increased. In addition, triacetate having a high degree of substitution of the acetyl group had the best heat-permeability, and the lower the degree of substitution of the acetyl group, the lower the heat-permeability.

On the other hand, as a result of observing the morphological changes of the wet or dry heat treated acetate film with an electron microscope, a large amount of micro voids having a diameter of 0.01 to 0.7 μm was formed on the surface as compared with before the heat treatment. This is caused by the formation of a large amount of voids in the acetate as the primary, secondary and tertiary bonded water, and the free and agglomerated, evaporated and rearranged water, which are hydrogen-bonded to the non-bonded hydroxyl group of the acetate. It seems to be. In this way, the light is refracted and scattered in the voids generated by the heat treatment, and it is determined that acetate exhibits devitrification.

Therefore, the inventors of the present invention determined that the method of reducing the amount of non-bonded hydroxyl groups containing water and hydrogen bonds in the acetate molecule could improve the devitrification, which is a disadvantage of acetate.

As described above, the present invention was able to be achieved through the investigation of the cause of the error of the acetate error and improvement studies. In other words, in forming a film, sheet or fiber in a dry or wet process, the unbonded hydroxyl group, which is the cause of the loss of acetate, is coordination-bonded or dipole-free, without increasing the process cost, lowering the fairness and lowering the physical properties. A functionally blockable additive was added to the usual acetate flake dope to obtain an acetate molded article with improved thermal stability. In addition, in the dry sacrifice of acetate, an appropriate amount of water was added to the acetone dope of the acetate flake together with the additive to obtain acetate fibers having improved thermal stability.

The additive used in the present invention is a halogen compound of acetone, a solvent of acetate, and a Zn, Co, or Sn halogen having high solubility in water, and adding 3 to 20% by weight of the weight of acetate flakes to the acetate flake dope. A cellulose acetate composition solution is prepared. At this time, when the amount of the halogenated compound of Zn, Co or Sn is less than 3% by weight, the heat-permeable effect is insufficient, and when it exceeds 20% by weight, the mechanical properties of the acetate molded product are remarkably decreased. In consideration of heat resistance devitrification and mechanical properties, the addition amount is preferably 4 to 10% by weight. Preferred halogen compounds of Zn, Co, or Sn in the present invention include, but are not limited to, zinc chloride, cobalt chloride, stannous chloride, stannous chloride, tin bromide, and the like.

In the present invention, when preparing the acetate flake dope together with the halogen compound of Zn, Co or Sn, acetone is 70 to 76% by weight in the dope, 1 to 5% by weight of water.

At this time, when the added amount of water is less than 1% by weight or more than 5% by weight, heat devitrification resistance is inferior. In view of the solution viscosity related to the heat resistance devitrification and the rust resistance of the dope, the amount of water added is preferably 2 to 4% by weight.

Using the acetate dope thus prepared, fibers, films and sheets prepared by conventional methods are subjected to alkaline, acidic and neutral hydrothermal treatment, and hydrothermal treatment under high temperature and high pressure of 90 to 140 ° C, particularly preferably 110 to 140 ° C. Even if the sample was heat-treated to 200 ° C., excellent heat devitrification and mechanical properties were shown. In addition, the amount of metal salt added to the initial dope remains as it is in the metal salt in the acetate molding prepared by the present invention. However, when hydrothermal treatment is carried out, a considerable portion of the initially added halogen compounds of Zn, Co or Sn is dissolved in water and removed. The concentration of the metal component remaining in the acetate after several hydrothermal treatments is characterized by being at least 100 to 500 ppm.

On the other hand, devitrification evaluation was performed as follows. After dropping a certain amount of acetate dope on the glass plate, a thin film is made with a coating blade, and then hot-air-dried at 85 ° C. to produce an average 55 μm acetate film. Subsequently, a 15 × 15 cm sized film was added to 200 cc of the aqueous solution of Table 1, and then treated at 90 to 140 ° C. for 2 hours using a high temperature and high pressure dyeing machine, and the sample was hot air dried at 60 ° C. Further, the film was subjected to dry heat treatment at 200 ° C. for 2 minutes using a test heat treatment apparatus (DHE, Werner Marthis AG, Switzerland). The devitrification evaluation of the film measured the absorbance at 400 nm with the spectrophotometer. The value obtained by dividing the absorbance obtained at this time by the thickness of the film was used for devitrification evaluation.

TABLE 1

Aqueous Solution Used for Hot Water Treatment

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following examples.

Examples 1-5 and Comparative Example 1

As shown in Table 2, a dope composition consisting of 25 grams of acetate flakes (54.2% superoxide), acetone 72 gr, 3 gr of water (3 wt% based on dope) and 1.5 gr of metal halide (6 wt% based on flakes) was prepared. After defoaming and filtering by the method, dropping a certain amount of acetate dope on the glass plate, a thin film was made with a coating blade, it was hot-air dried at 85 ℃ to prepare an average film of 55㎛. Subsequently, a 15 × 15 cm sized film was placed in 200 cc of the aqueous solution of Table 1, and then treated at 90 to 140 ° C. for 2 hours using a high temperature and high pressure dyeing machine, and the sample was hot air dried at 60 ° C. Further, the film was subjected to dry heat treatment at 200 ° C. for 2 minutes using a test stenter. The devitrification evaluation of the film measured the absorbance at 400 nm with the spectrophotometer. The value obtained by dividing the absorbance obtained at this time by the thickness of the film was used for devitrification evaluation. The devitrification degree of each film was evaluated and it shows in Table 3 below.

TABLE 2

Halogenated Metal Salts in the Doping Composition of Example 1

TABLE 3

Permeability according to the heat treatment of the acetate film prepared in Example 1

Examples 5-12 and Comparative Examples 2-6

A film was prepared in the same manner as in Example 1, except that a dope composition including acetate flakes (54.2% of superoxide) of 15 gr, acetone 82 gr, water 3 gr, and zinc chloride was prepared as shown in Table 4 below. . The prepared film was evaluated in devitrification as in Example 1, and is shown in Table 5 below.

TABLE 4

Addition amount of zinc chloride in the dope composition of Example 2 and the cutting strength and elongation of the film prepared therefrom

Cutting strength and elongation: UTM (Universal Testing Machine)

TABLE 5

Changes in the devitrification effect of high temperature, high pressure neutral, alkaline and acidic aqueous solution hydrothermal treatment and dry heat treatment after hydrothermal treatment

Examples 13-27 and Comparative Examples 7-16

As shown in Table 6, the film was prepared in the same manner as in Example 1 except that the dope composition was prepared by adding 25 g of acetate flakes (54.2% of superoxide) to 1.5 g of a halogenated metal, acetone, and water. Prepared. The devitrification degree of each film was measured and it shows in Table 7 below.

TABLE 6

TABLE 7

Permeability due to heat treatment of acetate film

As described above, the acetate fibers, films or sheets prepared according to the present invention are excellent in heat resistance and mechanical properties even under alkaline, acidic and neutral hydrothermal treatment under high temperature and high pressure of 90 to 140 ° C, and dry heat treatment up to 200 ° C. And the like. In addition, although the amount of metal salt added to the initial dope remains as it is in the metal salt in the acetate molding prepared according to the present invention, a large portion of the halogenated compounds of Zn, Co and Sn added initially are dissolved in water and removed. The concentration of the metal component remaining in the acetate after hydrothermal hydrothermal treatment is 100 to 500 ppm.

Claims (7)

A method for producing a cellulose acetate molded product from cellulose acetate flakes by a dry method, wherein the cellulose acetate flakes are dissolved in acetone and water, and then a halogenated compound of Zn, Sn or Co metal is 3 to 20% by weight based on the cellulose acetate flakes. A method for producing a heat-resistant cellulose acetate molded article, characterized in that the use of the cellulose acetate flake dope prepared by adding the cellulose acetate flake is 1 to 5% by weight based on the cellulose acetate flake dope. The method of claim 1, wherein the amount of acetone used is 70 to 76% by weight based on the cellulose acetate flake dope. A heat-resistant breakthrough cellulose acetate molding prepared by the method of claim 1. 4. The heat-resistant cellulose acetate molding according to claim 3, wherein the residual amount of Zn, Sn, or Co metal after the hydrothermal treatment of the molding at least once is 100 to 500 ppm. The heat-resistant cellulose acetate molding according to claim 4, wherein the hot water treatment temperature of the molding is 90 to 140 ° C. The heat-resistant cellulose acetate molding according to claim 4, wherein the hot water treatment temperature of the molding is 110 to 140 ° C. The heat-resistant cellulose acetate molding according to claim 4, wherein the molding is a film, a sheet or a fiber.