KR860002103B1 - Method of bleaching for cork - Google Patents

Abstract

A new bleaching method for cork was developed using hydrogen peroxide and sodium chlorite. Thus, 200g cork were treated with 200g sodium chlorite in a closed vessel maintained at 1 kg/cm2. After 10 min, the mixt. in the vessel was treated with 200g hydrogen peroxide in H2O (2:1 ratio) and the vessel was maintained at 60≰C and 2.8 kg/cm2 for 1 h to give bleached cork, which showed the original characteristics.

Description

Cork Bleaching Method

The present invention can be said to be a method of enhancing the discoloration effect by using any type of cork granular or plate-like, such as sodium hypochlorite and hydrogen peroxide simultaneously under a certain temperature and pressure. Cork, an oyster bark native to Korea, has slow growth process, thinner bark, harder tissue, and poor color than the cork obtained from Polchukal or Spain. Therefore, the purpose of the present invention is to improve the quality by applying flexibility and bright colors to the cork itself.

Originally, cork is a porous cell formed in the epidermis, the cortex, the primary part, and the secondary part of the bark. There are about 2 million porous cells in the cubic inch, and the structure is different from the wood part mainly composed of fibrous and tubular tissues. I will be different.

The chemical composition of the cork contains little cerose, contains a large amount of fatty acids, and contains trace amounts of lignin, ash, resins, and carbohydrates.

Cork's characteristics of these tissues and components consist of impermeable pore cells, each of which is a watertight and flexible compartment, and these cell aggregates are insulators and hardly pass through the liquid. Cork is chemically inert and hardly damaged by weak acids and weak bases or most organic solvents.

Because of the characteristics and structural characteristics of this cork, it is difficult to achieve the desired bleaching effect in the bleaching process unless the pretreatment process is performed before bleaching. It depends greatly on the reaction conditions.

The present invention considers the reaction relationship between the pretreatment agent and the bleaching agent of the cork components, and the method for effective bleaching by selecting the reaction conditions in relation to the structure and structural characteristics of the cork is described in detail as follows.

The present invention is added to the caustic soda 10 ~ 15% solution in a single step of granular and tubular in one step to increase the reaction conditions and then finished the pre-bleaching pretreatment step by increasing the reaction conditions and dehydrated In an airtight container that can be controlled by indirect heating means, keep the pressure at 1kg / cm ^2, and add cork to a saturated solution of sodium hypochlorite dissolved in water. Stir the temperature and keep the temperature around 35 ℃ and bleach for about 10 minutes. When the cork is partially discolored, it no longer discolors. At this time, the mixture of water and hydrogen peroxide mixture of 2: 1 is slowly added to avoid a violent reaction, and bleached for about 1 hour while maintaining the temperature at 55 ° to 62 ° C. at a pressure of 2.5 to 3 kg / cm.

In the above process, in the pre-bleaching step, the fatty acid ester or free fatty acid in the cork is saponified by the caustic soda solution, and the lignin contained in the trace amount is hydrolyzed and lignateed to remove and elute. Some of the resin may be eluted, and the components causing the bleaching disorder may be removed from the cork.

In addition, when the hydrogen peroxide and sodium hypochlorite are decomposed during the bleaching process, the reaction is exothermic, so it is necessary to pay close attention to temperature control. If the hydrogen peroxide and sodium hypochlorite are mixed at the same time, bubbles are generated at the same time as the bubbles are generated at the same time. In particular, in the case of particle cork, bubbles are completely surrounded and the cork particles are blocked from contact with the bleach solution, which causes bleaching disorder. Therefore, by slowly adding sodium hypochlorite dilution solution in two stages in a partially bleached state by diluting the hydrogen peroxide dilute solution slowly, it is possible to prevent bubbles from being generated, thereby achieving a desired bleaching effect.

In addition, it was found through the long test that bleaching treatment in hydrogen peroxide dilution solution was more effective in the order of bleach administration.

In addition, the temperature and pressure in the bleaching process are also important factors for achieving the present invention. When the mixture solution of hydrogen peroxide and sodium hypochlorite reaches 62 ° C or higher, the cork begins to gel and further collides when the temperature rises. This results in the loss of cork's properties. The reason for this may be attributed to the rapid progress of oxidation decay due to temperature rise in the presence of a large amount of oxygen generated by the bleach used in the bleaching process. In addition, under normal pressure, bubbles are generated and cause bleaching disorders, and decomposition reactions occur in a short time. Therefore, the time for bleach solution to penetrate or contact the cork becomes short, so it is difficult to expect complete bleaching. The bleaching effect is delayed and the contraction of pressure occurs in the cork itself, which reduces the apparent volume of cork and damages the physical properties.

As mentioned above, the bleaching pretreatment process, temperature, pressure, and the order of bleach treatment are important factors for achieving the present invention.These factors are properly selected as in the present method and do not bleach without damaging the characteristics of the cork. Excellent cork can be obtained.

Thus, it can be seen that the effect of the method according to the present invention becomes more apparent as shown in the table by comparing the embodiment of the cork bleaching method according to the present method with those deviating from the present method.

Example 1

200 g of brown coke after the pre-bleaching process was added to 200 g of saturated sodium hypochlorite solution dissolved in water contained in an airtight container that can be controlled by a heating means, and decolorized with stirring while maintaining an internal pressure of 1 kg / cm ² . to maintain the internal pressure after the first hydrogen peroxide solution is slowly added to 200g 2.8kg / cm ^2, a solution temperature of 60 ℃: progress and for about 10 minutes has elapsed and the temperature of the mixture ratio 2 to the water when the rising around 32 ℃ As a result of about 1 hour of decolorization, a pale beige bleached cork with excellent bleaching rate was obtained, which showed a 1.2% reduction in the apparent volume reduction without losing the characteristics of the original cork.

Comparative Example 2

To the solution of bleached pre-bleached brown cork with a saturated solution of sodium hypochlorite as in Example 1, 200 g of hydrogen peroxide solution having a mixing ratio of 2: 1 was gradually added, and the internal pressure was 2.8 kg / cm ² . As a result of bleaching for about 1 hour by maintaining the temperature around 78 ° C, the intrinsic properties of the cork were lost, resulting in a milky semi-gelatinized cork having a reduced apparent volume reduction of 38.5%.

Comparative Example 3

To the solution of the brown bleach after the pre-bleaching pretreatment with saturated sodium hypochlorite solution as in Example 1, 200 g of hydrogen peroxide solution having a mixing ratio of 2: 1 was slowly added, and the internal pressure was 6 kg / cm ² , and the solution temperature was After bleaching at about 60 ° C. for about 1 hour, the apparent volume fraction was reduced to 11.7%, yielding a beige cork with markedly reduced elasticity.

As shown in Example 1 and Comparative Examples 2 and 3 above, the bleaching treatment method according to the present invention has a high bleaching rate, almost no volume reduction rate, and is a method of preserving the characteristic of the cork as it is, and the color is bright and flexibility can be utilized. It can increase the added value and can be used as a versatile material for wallpaper, interior material, handbag and bag skin.

Claims (1)

As described in the specification, by applying a known method to the saturated solution of sodium hypochlorite in a closed container capable of temperature control by an indirect heating means in which the pre-bleaching pretreatment of the cork was maintained at a pressure of 1 kg / cm ^{2, the} discoloration of the stirring was carried out. When the temperature rises to around 32 ℃ after about 10 minutes, slowly add the mixed solution of water and hydrogen peroxide, and then bleach for about 1 hour by maintaining the internal pressure at 2.5 ~ 3kg / cm ² and the solution temperature at 55 ° ~ 62 ℃. Cork bleaching method characterized in that.