JPH03502945A - How to bleach cotton - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] How to bleach cotton 1 basket hill! Bleaching cotton, wool and silk fibers and blends of such fibers can be used to bleach yarns and fabrics. It is a process step in the manufacture of textiles and can be performed at several stages in the manufacturing sequence. that sometimes loose fibres, threads in skeins or packaged form, singed and unsized and This is done on the fabric before or after mercerization. The purpose of bleaching is good absorption Makes a clean and white product without losing its strength and physical strength. There is a particular thing. For fabrics containing cotton, desizing and scouring may be performed before bleaching. or in combination, and for yarns, bleaching Scouring can be performed alone or in combination with scouring.

The desired whiteness of a bleached item, article or product depends on whether it is to be dyed or not. Depends on whether or not. They are best when the finished product should be white. Optical brighteners are usually combined with bleaching chemicals in the bleach bath. Can be added together. Optical brighteners are not required for products that are to be dyed or printed. Instead, the product is treated with a mild bleaching process known as normal pre-bleaching that does not contain optical brighteners. In the description and claims of this invention, the term bleaching refers to pre-bleaching and bleaching. Back jll technique that should be understood to include both white processing Fabrics and yarns are free from spin finishes, Corning oil, as well as natural and foreign impurities. And for fabrics, in order to remove desizing agents, it is necessary to obtain satisfactory whiteness and Bleached to create absorbent fabrics and threads.

Pre-bleaching treatments can include desizing and scouring. The sizing agent is removed from the fabric as completely as possible. Remove completely and evenly. The remaining glue has uneven dyeing and stiffness that varies Vines provide texture. Descaling can be done using neutral enzymes, depending on the sizing agent to be removed. solution, or commonly use sodium carbonate, sodium bromide or hydrogen peroxide. It is carried out in a basic solution.

Scouring is the process of softening cotton fibers by saponification and emulsification to obtain good whiteness and absorbency. to remove oils, waxes and fats, or pectins, hemicelluloses and proteins. carried out to pre-treat the fibers for the subsequent removal of these substances containing materials . During scouring, moat, seed coats and their Other fragments are also preprocessed.

During the bleaching stage, oxidizing chemicals are often used to remove impurities from the fabric and decolorize it. Apply. The bleaching process serves several purposes: High and uniform absorbency of yarn or fabric for water, dyes and finishes.

Sufficiently low levels of particles (moats, seed coats, fragments, funiculi, etc.) high content and sufficiently high and uniform whiteness.

Fibers, yarns and fabrics must not be damaged and the degree of cellulose polymerization must remain high. Should remain.

The whiteness of the fabric should remain stable upon storage.

Oxidizing chemicals used for bleaching include chlorine chemicals (hypochlorite, chlorite, and chlorine dioxide), hydrogen peroxide and sulfur derivatives.

Hydrogen peroxide is the most widely used bleaching agent for textiles today.

Hydrogen peroxide has many important advantages over other bleaching agents, including: This produces a stable white color and the bleached product has fats and waxes solubilized. , is highly hydrophilic as it is removed by the hot alkaline solution used.

Can effectively bleach cotton husks.

The reaction product is relatively non-toxic, it decomposes into oxygen and water, i.e. It is generally healthy.

It is compatible with most fibers.

The number of operations and steps in the bleaching process can be reduced, e.g. scouring and peroxidation Can be used with hydrogen bleach.

Some disadvantages of hydrogen peroxide as a bleaching agent include: Catalytic decomposition of hydrogen peroxide is affected by the presence of iron, nickel, copper and other heavy metal ions. The vine grows. Catalytic decomposition of hydrogen peroxide at high concentrations causes cellulose degradation. . Severe degradation results in broken fibers and pores in the fabric.

Stabilizers are added to control hydrogen peroxide decomposition.

Silica-based stabilizers precipitate on the yarn or fabric under conditions that lead to non-uniform Causes staining.

Hydrogen peroxide is a relatively expensive chemical.

U.S. Pat. No. 1,163,438 to Mueller describes an unbleached material to be bleached. is immersed in an aqueous alkaline bath, and the bath liquid is subjected to the action of molecular oxygen or air. A bleaching method consisting of: In a preferred embodiment, the alkali under pressure is Oxygen or air is forcibly introduced into the bath to heat said bath and at the same time air or air is introduced into the bath. Forced introduction of oxygen and presence of non-alkaline compounds of metals, such as manganese carbonate however, it takes 16 hours when no heavy metal compounds are present in the bath, and e.g. 12 hours when manganese is present in an amount of 0.01%. This time consuming The method is compatible with other, more rapid bleaching processes, such as overheating, which is also a method currently utilized. It was abandoned in favor of bleaching with hydrogen oxide.

New Year's Day J and L Xiong The purpose of the invention is to greatly reduce the amount of conventional bleaching agents used to clean products containing cotton fibers. Bleaching has maximum whiteness and absorption power.

Another object of the invention is to use oxygen alone or conventional bleaching agents such as hydrogen peroxide or hypochlorite. Products with a higher degree of whiteness than conventionally obtained by using sodium chloride alone. It's all about bleaching.

Yet another object of the invention is to provide rapid bleaching with hydrogen peroxide to a certain degree of brightness. There are many things.

Yet another object of the invention is to use adjuvants such as optical brighteners and stabilizers in bleaching processes. The goal is to reduce the amount.

Another purpose is to avoid spills when using sodium hypochlorite in bleaching cotton-containing products. The purpose is to reduce the amount of chlorine chemicals in the liquid.

Cry 101jo The present invention provides products with an oxygen-containing gas dissolved or dispersed in an alkaline processing liquid at high temperatures. Bleach products containing cotton fibers using conventional bleaching agents by subjecting them to It's about whitening. The oxygen-containing gas contains at least 50% oxygen, preferably less Both are composed of 99% oxygen, that is, pure oxygen gas. The remainder of the gas is nitrogen or noble gas. It is an inert gas such as

This treatment with oxygen gas is an alkaline solution in the absence of traditional bleaching agents such as hydrogen peroxide. This can be done at the sexual processing stage. Oxygen gas is supported as much as possible by stirring the liquid. This prevents dissolved oxygen from collecting on top of the liquid in the container. Dissolved in the processing liquid by means of a blowing device that disperses or spreads the gas as uniformly as possible. , or by introducing oxygen into the headspace of the expansion vessel or processing vessel of the bleaching equipment, In order to dissolve or entrain the raw gas, the processing liquid is stirred and dissolved in the processing liquid. Traditional After such treatment with oxygen gas in the absence of bleach, the product is free from bleach, preferably Treat in an alkaline bleach solution containing hydrogen peroxide. Alka using oxygen gas The oxidation treatment can be a scouring step after enzymatic descaling, or alkaline descaling. It can be a combined stage of drawing and scouring.

According to another preferred embodiment, the treatment with oxygen gas in the alkaline liquid comprises: In this embodiment, carried out in the presence of a bleaching agent, i.e. in an alkaline bleach solution, conventional A desizing step and a conventional scouring step can be performed prior to the bleaching step, or For certain applications and quality requirements, one or both of these conventional pretreatment steps can be used. can be omitted.

According to yet another embodiment, the product comprises a bleaching stage in the absence or presence of a bleaching agent. It can be subjected to the action of oxygen after the floor. Required conditions are high temperature treatment with oxygen This is done in an alkaline solution.

According to yet another embodiment, the method comprises the use of ozone in the form of a mixture with an oxygen-containing gas. In this case, part of the oxygen and inert gas is replaced with ozone. Ozone concentration is representative Typically, it can range from about 6% to about 0.5%.

Oxygen can be used to bleach cotton to high brightness in a hot alkaline treatment step. comparison This whiteness is obtained by using oxygen in a hot alkaline solution at high temperatures. About 13. is suitable as so-called pre-bleaching before dyeing or printing the product. By using a pH of up to 7 and a temperature of at least 90°C, Pre-bleaching for e.g. 1-2 hours without reducing the degree of polymerization of the cotton below the level It can be done with

in an alkaline solution, in the presence or absence of conventional bleaching agents such as hydrogen peroxide, The essential requirements for obtaining a bleaching effect with gaseous oxidizing agents such as oxygen and ozone are: It is the delivery of a gaseous oxidizing agent to a reaction site on or in the fibers to be bleached. oxygen can be transported directly from the gas phase to the thin liquid layer surrounding the cotton fibers, or initially It is dissolved in a large volume of liquid and then transported to the cotton fibers by forced circulation of the liquid.

Oxygen acts as a bleaching agent at high temperatures under alkaline conditions.

The processing conditions used for bleaching with hydrogen peroxide can be applied to bleaching with oxygen. . Oxygen can therefore be used with hydrogen peroxide or hypochlorite.

The overall reaction time for oxygen bleaching reactions is influenced by the concentration of oxygen at the reaction site. increased bleaching efficacy expressed as whiteness increase versus bleaching time The result is therefore an increased oxygen partial pressure, both physically dissolved and free oxygen in the liquid phase. affected by increased concentration of oxygen in the processing liquid, and increased liquid circulation turbulence. Ru.

Pressurized bleaching equipment, such as autoclave, car, package dyeing machine, skein Dyeing machines, winches, jiggers and jet machines are well suited for oxygen bleaching applications. Ru.

Oxygen is used in a closed container in bleaching equipment where good contact between gas and liquid can be achieved. For the dissolution of oxygen, which can be added directly to the vessel or connected to a bleaching device It can be added in a separate specially designed container.

Purging and/or pressurizing the headspace in a jet machine with oxygen This is an example of direct addition of Strong liquid flow in jet machines requires good contact between gas and liquid. oxygen is dissolved in the liquid. The fabric moves through the headspace. Because of the movement, oxygen is also dissolved directly in the liquid layer on the fiber surface.

Oxygen can also be introduced into the J-box carrier in which the moistened fabric is moved. Ru. In the J-box, at least the upper part is a liquid void (excluding the liquid layer on the fabric). Ru. The oxygen in this upper part diffuses into the liquid layer and thus reaches the point where the bleaching reaction takes place. Spread.

Suitable process conditions for oxygen bleaching are as follows: Bath ratio (fiber to liquid) 1 :1 to 1:50, preferably 1:1 to 1:10: Temperature ("C) 60-130, preferably 75-115: pH 9-13.7, hydrogen peroxide present Below is preferably 10-1 2. In the absence of hydrogen peroxide is preferably 13 to 13.5.

Total pressure (bar) (gauge) O~10. Preferably O-6; Bleaching time (minutes) 10-100, preferably 15-60° Oxygen is added to the agents normally added to bleach baths, such as wetting agents, sequestering agents, and stabilizing agents. agents, pH buffers, and optical brighteners, as well as acids such as hydrogen peroxide and hypochlorite. Figure 1 is a schematic diagram of a laboratory yarn package bleaching machine.

Figure 2 is a schematic diagram of a jet bleaching machine with several means for introducing oxygen. Ru.

FIG. 3 is a schematic representation of a portion of a continuous bleaching line.

Figure 4 shows the whiteness versus time for bleaching cotton fabric with oxygen at different pHs. This is a graph showing.

Figure 5 shows peroxidation for bleaching cotton fabrics with and without oxygen treatment. It is a graph showing the degree of whiteness with respect to the amount of hydrogen fed.

FIG. 6 is a graph similar to FIG. 5.

Figure 7 shows the bleaching of cotton fabrics without and with oxygen treatment before treatment with hydrogen peroxide. 2 is a graph showing the degree of whiteness versus the amount of hydrogen peroxide fed.

Figure 8 shows hydrogen peroxide in the presence and absence of oxygen, that is, in the presence of nitrogen. 1 is a graph showing whiteness versus time for bleaching cotton fabric.

sunny FIG. 1 shows a modified yarn package 11 containing an autoclave 10 for bleaching the yarn package 11. A laboratory bleaching machine is schematically illustrated. Autoclave 10 is changed via lines 6 and 7 It is connected to valve 4. The outlet 3 of the valve 4 connects two branch lines 2° and 28. It is connected to line 8 with. Each of lines 20 and 28 has a respective valve 26 and 18 are provided. Line 28 is connected to line 16 and has one end It opens into the expansion vessel 13. Oxygen source 14 is connected via line 15 with valve 19. and communicates with line 16. The bottom of the expansion vessel is line 9, pump 5 and line 25 to the inlet opening of the change valve 4. Line 20 is in line with line 8 Connected to In9. Furthermore, the top of the autoclave 10 is connected via a line 22 to Open in line 21 connected to line 16. Line 21 and line 22 A first valve 17 is provided between the lines 16 and a second valve is provided on the opposite side of the line 22. Lube 23 is provided.

Thread package 11 has a central channel 24. One end of this channel 24 is It is located on the vibe socket 12 connected to the vibe 7. The other end of channel 24 is closed In the operation described above, the thread package 11 is placed in the autoclave 10, When the first pump 5 is started, which feeds water and chemicals into the bleaching machine, the liquid flows through line 9, Pump 5, line 25, change valve 4, line 7, thread part in autoclave 10 Circulation in the form of a loop from the expansion container 13 via the channel 24 passing through the cage 11 do. The liquid from autoclave 1o goes to line 6, change valve 4, lines 8, 28 and and returns to the expansion container 13 via the vibrator 16. Valves 23.17 and 26 are closed. It will be done. Valve 17 allows liquid flow only in the direction from line 22 to line 16. It can be a non-return valve. The circulating fluid is e.g. between the pump 5 and the line 20. It is heated to the desired temperature by a heat exchanger (not shown) in line 9. Desired temperature When the desired pressure is reached, oxygen is pumped through lines 15 and 16 until the desired pressure is achieved. is supplied to the expansion chamber 13. The expansion vessel 13 is then evacuated to remove air, and the acid Supply the raw material again. Repeat this method e.g. 4 times, vibrator flowing in line 16 The liquid from 8 is then injected into the headspace of the expansion vessel 13. in headspace Since there is a prevailing oxygen pressure in the liquid, oxygen dissolves in the liquid. Auto credit after scheduled time. The direction of liquid flow to and from tube 1o can be reversed by switching valve 4. Turn around. This experiment involved pumping the liquid into the vibrator socket 12 via line 7 and Since the flow started from the inside of the cage 11 to the outside, the flow direction is reversed. into the autoclave 10 via line 6 and the thread package 11 into the autoclave 10. The direction is from outside to inside. The reversal of the flow direction is due to the uniformity of the yarn in the package 11. At regular intervals, for example every 5 minutes, the expansion is done relatively often to make one bleach. The chamber 13 is evacuated to drive out the gas and then additional oxygen is added. Bleach after bleaching is complete. Drain the white liquor and then neutralize the thread, wash and dry.

Normally the line 28 containing the valve 20 is not present in laboratory equipment; in such cases the line 28 containing the valve 20 is Line 8 merges with line 20 and exits outlet 3 of change valve 4 from autoclave 10. These liquids are fed directly into line 9 and returned to valve 4 via pump 5. expansion capacity Introducing oxygen-containing liquid from vessel 13, pump 5, valve 4 and autoclave 10 To do this, a portion of the liquid stream is removed from the autoclave 10 via line 22, The expansion vessel 13 is fed via lines 21 and 16. The corresponding liquid volume is expansion chamber 1 FIG. Schematic representation of a jet machine for bleaching fabric with a clave 30, the fabric is arranged in a closed loop and continuously via bypass conduit 31 in the direction indicated by arrow 50 Forced. Bleach solution is pumped through line 49 to autoclave 3 by pump 34. 0 and placed in an autoclave via the vibrator 40 and jet nozzle 33. It is returned to the bypass line 31. The bleaching agent is pumped from the container 36 by the pump 35. Add to white liquor. The expansion container 43 is connected to the vial via an inlet line 40 and an outlet line 38. Valve 37 may be connected to line 44 between line 38 and 40. There is a valve 42 in the line 41 connecting an oxygen source (not shown) to the expansion vessel 43. This is provided.

During operation, valve 37 is closed and air is drawn from autoclave 30 via line 49. The drawn liquid is transferred to the expansion container 43 via the vibrator 44 and the line 38.

From the expansion vessel 43, the bleaching solution returns to the vibe 44 and is bypassed via the jet 33. It is introduced into line 33. Oxygen is transferred from the oxygen source to the expansion container 43 via the vibrator 41. supply Oxygen is supplied to vessel 43 in the same manner as shown in connection with FIG.

In FIG. 2, other possibilities for introducing oxygen gas into the bleaching process are also shown. , an oxygen source can be connected to line 47 with valve 48 . Line 47 is vibe 4 4, and a sintered body (not shown) can be provided at one end to create small bubbles. Wear. These bubbles are easily dispersed in the liquid passing through the vibrator 44. This method The elements can be continuously introduced into the machine. Oxygen flow can be adjusted with valve 48. this method When oxygen gas is introduced in the expansion vessel, valve 37 is opened and valve 39 is closed. Neither 43 nor valve 37 can be present.

Yet another possibility is to directly connect the headspace of the autoclave 30 via line 45. The first step is to introduce oxygen into the base or line 51. The flow of oxygen gas is through valve 4. 6 and 52, respectively. Line 51 preferably includes A sintered body is provided at one end that opens.

Figure 3 shows part of a continuous bleaching line, in which the fabric 61 to be bleached is coated with a chemical applied to the fabric. In order to moisten the air, it enters the saturator 62 on the left side of the figure. These chemicals are in the form of aqueous solutions. It can contain sodium hydroxide and hydrogen peroxide. Exit saturator 62 The fabric may first be passed through a pair of rollers 63 to remove excess liquid from the fabric. The fabric is transferred from the saturator 62 to the J-box carrier 64, where it is bleached. occur. The residence time of the fabric in the carrier is sufficient to bleach the fabric; Otherwise, several saturators and carriers are connected in series. J-Bot From the scrubber 64 the fabric is transferred to one or several washing stations 65.

Normally, J-box carriers use water vapor indirectly or directly to maintain the fabric at a set temperature. Heat it up. The J-box carrier 64 acts directly on the fabric 61 and passes through the line 66. The water vapor is then heated. Apply bleaching solution to the bottom or heel of the carrier 64. That is, the hydrogen peroxide solution can be added from the tank 67 via the vibro 9 with the pump 68. I can do it. Hydrogen peroxide solution is removed from the carrier 64 via line 70, In the J-box car, there is no recirculation of bleach solution to the bottom of the car.

When supplementing conventional bleaching with hydrogen peroxide with oxygen bleaching, oxygen is used alone or with water vapor. via line 66.

Oxygen is dispersed in the carrier and diffused into the liquid layer surrounding the fibers of the fabric.

Figure 4 shows a graph of brightness versus time at different pH values for bleaching with oxygen. The temperature is 104°C and the total oxygen pressure is 1.3 bar (gauge). Additionally, it can be clearly seen that the whiteness increases as the pH increases.

Examples of cotton bleaching used for bleaching cotton and cotton-polyester yarns and fabrics are shown below. These examples, shown in Figure 1, show that when bleaching is augmented with oxygen, the hydrogen peroxide feed rate is This shows that it can be reduced by up to 80%.

K standing father-in-law Example 1 Scoured but unbleached cotton fabric was placed in an indirectly heated rotating auto oven under the following conditions: Processed in Reve (750 mβ volume): Bath volume (mβ) 500 Fabric to bath ratio 1:50 Temperature ('C) 95 NaOH concentration (mol /An　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　60 rooms Pressure at temperature (MPa) (gauge) See Table 1. and pressurized with oxygen. Headspace capacity was % of autoclave capacity The effects of the treatments on , whiteness and fluidity are shown in Table 1.

In all experiments, whiteness was measured with the 15O2470 standard method. The flow rate is 5IS6 Measured with 50038 standard. Fluidity measures the degree of polymerization of cellulose fibers in cotton This is an indirect method.

A low fluidity value indicates a high degree of polymerization; a rhe fluidity value indicates a high degree of polymerization. should be less than 15 in order to maintain acceptable shear strength.

Table 1. Whiteness A before and after treatment with oxygen or nitrogen, before treatment --57,6 1,4 B. After treatment Nitrogen 0-2 61.0 1.6 After C1 treatment Oxygen 0゜2 72.4 2.3D, after treatment Oxygen 0.4 73.6 2゜l Samples B and D were then bleached with hydrogen peroxide did. Bleaching conditions were as follows: Fabric-to-bath ratio 1:1 Temperature ('C) 95 Magnesium sulfate (for fabric) (%) 0.1 NazS iOs (About fabric) (%) 1. OpH (adjusted with Na leaf) 　　　　　10.6-11.0 hours (minutes) 60 Amount of hydrogen peroxide fed See Table 2 White color after bleaching with hydrogen peroxide The results in Table 2 are shown in Table 2. peroxidation to reach a certain brightness compared to no pretreatment with oxygen. This indicates a 50-75% reduction in hydrogen requirements.

Water absorption (suction height) of oxygen-bleached fabrics after bleaching with a reduced feed rate of hydrogen peroxide shows the same good performance after pretreatment without oxygen as after bleaching with a higher feed rate of hydrogen peroxide. (see examples D1 and B2).

Water absorption occurs when the edge of a fabric sample is brought into contact with a colored aqueous solution and the colored aqueous solution moves vertically. The suction height values in Table 2 were evaluated as the distance moved (suction height) for each trial. The fees are shown below.

Table 2. Hydrogen peroxide bleaching conditions and conditions for bleaching fabrics pretreated with nitrogen or oxygen Properties of fabric after bleaching.

See Table 1 for the pretreatment conditions, and the amount of hydrogen peroxide added is based on the weight of the fabric. 00%) calculated as hydrogen peroxide.

B 61.0 1.4 44,498I 　　　　Nz　　O,2577,82,461,6982Nx　　　O,5 080,13,159,6583Na 1.00 81.2 3.5 51,58D 0.4MPa0i 73.6 2.1 52.53.49.50DI O,4MPa0* 0.25 80. 6 3.4 60,58,56,5402 0.4MPa0i 0.5 0 81.2 4.1 60,56,52,58D3 0.4MPa0* 1.00 81.2 5.8 63, 63, 57.57 Example 2 Scoured but unbleached cotton fabric was placed in an indirect heating rotary autoclave ( 750mg capacity): Temperature capacity (I!lβ) 750 Fabric to Bath Ratio 1:B0 Temperature (''C) 95Na011 concentration (mol/I2) 0 ．． 1 hour (minute) 60 Pressure (at 95℃) (kPa) 700 Pressurize autoclave with oxygen did. The headspace capacity was a month of the autoclave capacity.

After the oxygen-alkali treatment, the fabric was bleached with hydrogen peroxide.

The conditions for hydrogen peroxide bleaching were as follows: Fabric-to-bath ratio 1:1 Temperature (’C) 95 peracid on fabric Hydrogenide (%) 0.25Mg5O4 (for fabric) (%) 0.1Na *5iOs (for fabric) (%) 1.0 pH (adjusted with NaOH) 10.8 hours (minutes) 60 The evaluated properties of the fabric after different processing stages are shown in Table 3. Differences in Table 2 Evaluated properties of the fabric after the processing step E, untreated 57.6 1.5 3.5F, after 02 treatment 68 ．． 7 1.6 0-1 (*) Cleanliness is the Swedish In5t Used by itute for Textile Research (TEFO) (5=poor, O=no impurities).

Oxygen-alkali treatment followed by bleaching with <0.25% hydrogen peroxide results in 0 after alkaline treatment. ．． Example 1 shows that bleaching with 50 to 100% peroxide gave the same whiteness as bleaching. In this example, a reduced charge of peroxidation following oxygen-alkali treatment Showing that hydrogen peroxide bleaching with hydrogen provides complete particle removal, i.e. superior cleanliness. are doing.

Example 3 Bleaching of cotton-polyester yarn in a laboratory packaging machine (Figure 1).

The packaging machine was loaded with one yarn package cage (weight 1 to gram). Bleach bath is threadba The tube was pumped alternately in and out through the cage. The thread to liquid ratio is 1:10. It was.

The headspace of the expansion vessel was pressurized with oxygen to dissolve the oxygen in the bleach bath.

The drug preparation and procedures are shown in Table 4. After final washing and drying, the oxygen-enhanced bleached yarn is It had the same brightness as the control bleached yarn (bleached only with hydrogen peroxide).

Table 4. Medicinal preparation based on thread 1 (control) 1.0 3.0 5.0 0.0 11.1 10.72 　　　　　　　0.5　3.0　　1.0　0.4　　11.510.9 Each test At 1.0% optical brightener was added.

The procedure for Experiments 1 and 2 was as follows: 1. Add drugs in the order listed in the table.

2. Heat to 115°C for 30 minutes and drain.

3. Refill with water, wash at 88°C for 10 minutes, and drain.

4. Refill with water, wash at 71°C for 10 minutes, and drain.

5. Refill with water, add 0.25% chelating agent and 0.25% wetting agent, 60 Wash for 10 minutes at °C and drain.

6. Refill with water, add 1% acetic acid and 1% silicone softener, and heat at 38°C for 1o. Rinse and drain.

Example 4 Bleaching experiments were carried out in the jet bleaching machine shown in FIG.

Experiment 11゜ Valves 46 and 48 were closed. Cotton fabric, water, 0.024 m.

Fill the machine with l/β Na leaves and 0.5% hydrogen peroxide (fabric standard), and set the temperature was raised to 95°C. Bleaching time was 30 minutes. Then use the fabric as a reference again. First, 0.5% hydrogen peroxide was charged into the machine and bleaching was continued for 30 minutes at the same temperature. An additional charge of 0.5% hydrogen peroxide was added and bleaching of the fabric continued for an additional 30 minutes. acid No ingredients were added. Samples were taken after each bleaching period of 30 minutes.

Experiment 12゜ Valves 46 and 48 were closed. Cotton fabric, water and 0.024mat/β Na OH was charged into the machine and the temperature was increased to 95°C. Head space of expansion container 43 3.5 bar (gauge) of oxygen was introduced into the bath, and the fabric was bleached for 30 minutes ( (no hydrogen peroxide present), then release oxygen from the headspace and remove the fabric from the base. 0.65% hydrogen peroxide was added to the bleach solution. Bleaching time was 30 minutes The fabric was then bleached with two additional 30 minute bleach cycles. drift before the start of each cycle. To the white liquor was added 0.5% hydrogen peroxide based on the fabric.

Figure 5 shows the variation of bleaching conditions as a function of hydrogen peroxide loading for Experiments 11 and 12. Indicates the degree of whiteness between

Compared to 89% brightness and 60 minutes total bleach time, oxygen pretreatment reduced the brightness of hydrogen peroxide by 5%. It means 0% savings.

Example 5 Another experiment was conducted using the jet bleaching machine shown in FIG. This experiment (Experiment 13) was The first 30 minutes started in the same manner as in Example 4, Run 12. Then, based on the fabric Pour 0.8% hydrogen peroxide into the device and bleach for 30 minutes without oxygen. Bleaching was continued for 30 minutes without addition. Sample after each bleaching cycle I took it.

The graph in Figure 6 shows hydrogen peroxide for Experiment 11 in Example 4 and Experiment 13 above. Oxygen prebleaching followed by hydrogen peroxide bleaching, which shows the brightness relative to the amount of the fabric Based on 0.8% hydrogen peroxide, total bleaching time is 90 minutes, same time However, peroxide containing only hydrogen peroxide, which is 1.5 to 1.6% based on the fabric. An example that gave the same whiteness as hydrogen bleaching For the experiment (Experiment 14), fabric and water were placed in the jet bleaching machine shown in Figure 2. , 0.8% hydrogen peroxide based on fabric, and 0.024 mol/it The treatment solution containing NaOH was heated to 95°C and oxygen was added to the head of the expansion vessel. A pressure of 3.5 bar (gauge) was supplied to the dosing space. Try after 30 minutes The bleaching was continued for 30 minutes without further addition of hydrogen peroxide. given full time Oxygen was present at the same pressure.

In FIG. 7, black symbols indicate Experiment 11 of Examples, and open symbols indicate Experiment 14. represents. Combining oxygen and hydrogen peroxide bleaching with 0.8% hydrogen peroxide in 60 minutes. The combination gave the same brightness as a 1.5% hydrogen peroxide charge in 90 minutes.

The absorbency of all bleached samples in Examples 4-6 was excellent. A white experiment was conducted on the thread. In each experiment, 6 pieces of yarn with a total weight of approximately 4.9 g Bleached packaging. Using equipment similar to that shown in Figure 1, but A down-flow bubble contactor was used to introduce oxygen. Liquid volume The amount was about 1 OI2, which was a liquid to thread ratio of about 14:1. this is This is a higher value than normally used. Hydrogen peroxide and fluorescein in proportion to the weight of yarn A photobrightener was added. Defoamers, wetting agents, agents for controlling water hardness, hydrogen peroxide The concentrations of stabilizers and other agents used such as sodium hydroxide were determined in all experiments. The same concentration was used in the experiment. Acid absorption by a liquid is due to oxygen absorption in the liquid at actual temperature. The solubility was limited to A large proportion of liquid-sealed yarns has a large amount of dissolved oxygen per g in yarn 1 However, with conventional means such as bubble contactors, the oxygen concentration is always at its maximum. Oxygen can be dissolved in the liquid in an amount that is close to the value.

The following bleaching experiment was conducted.

Vl, comparative example, normal hydrogen peroxide charge of 2% based on yarn, normal pH: V2. Using oxygen, reduced amount of 1% hydrogen peroxide based on thread, normal pH ; V3. Using oxygen, reduced amount of hydrogen peroxide of 0.5% based on thread, normal pH; V4. Oxygen-free, 1.5% hydrogen peroxide based on thread, 25% reduction, reduction pH: V5. Oxygen-free, 75% reduction with 0.5% hydrogen peroxide based on yarn pH: V6. Oxygen usage, 75% reduction with 0.5% hydrogen peroxide based on yarn, decreased pH.

Once the yarn was introduced into the bleaching equipment, water and chemicals were added in the order shown in the table below. after that The temperature was increased from a starting temperature of about 30°C to a maximum temperature of 95°C in about 20 minutes. child This corresponds to a temperature rise of approximately °C/min. In experiments using oxygen, bubble contact It was pre-added into the heating phase via a container. When the maximum temperature is reached, this temperature is 45℃ I kept it.

Bleaching was stopped by removing the solution. The yarn was then washed with water.

To neutralize the residual alkali, 40mj2 of concentrated acetic acid was added to the washing water. Centrifuge and air dry.

The bleaching conditions are shown in Table 5, and the amounts of optical brightener and hydrogen peroxide are calculated based on the yarn. . The results are shown in Table 6.

Table 5. Cotton thread bleaching conditions, hydrogen peroxide and optical brightener dosage are based on the thread. Shown in %.

Wl 4.86116 2.0 348 0.25 0W2 4.96125 1.0 375 0.25 3.5W3 4.9 3130 0.5 375 0.25 3.5W4 4.9 12 5 1.5 100 0.25 0W5 4.8 125 0. 5 80 0.25 0W6 4.7 125 0.5 5 0 0.25 3.5 Table 66 Whiteness for bleached yarn, white for UV light Color index (CIE-1ab) and fluidity Wl 101.8 2.4W2 97.9 2, IW3 90.1 W4 88.3 W5 45.9 W6 64.7 (*) The fluidity was measured only for samples W1 and W2, and was the highest in this test. I was given rough conditions.

According to Table 6, the fluidity value was less than 2.5 l. Due to the low flow rate value, the strength I thought that there was no need for such a test.

Example 7 bleaching agent and cotton fabric in jet bleaching machine with fabric capacity of 160-180Kg In experiment x1, a normal amount of hydrogen peroxide was added to maintain the atmospheric pressure of the air. Normal patch times and temperature cycles were followed. Experiment x1 was done using the standard bleaching method. be. The resulting whiteness as CIE without UV was 63.5 units.

In Experiment X2, one machine charged with 60% of the amount of hydrogen peroxide as in Experiment The air in the tank was purged until it was replaced with oxygen gas. Slight gauge pressure of oxygen gas ( Normal batch times and temperature cycles were followed keeping the temperature at about 1 bar gauge.

The resulting whiteness as CIE without UV was 63.7 units.

The initial whiteness of the fabric in both experiments was 20.4 units (CIE without UV) In this example, oxygen replaced 40% of the hydrogen peroxide required for standard bleaching. This shows that the same whiteness can be obtained by substitution. Oxygen consumption is 2. It was 0m3.

Example 8 In this example, three experiments were conducted to demonstrate the synergistic effect of hydrogen peroxide and oxygen.

These experiments were performed in a single-package laboratory machine modified at atmospheric pressure. The experiment is Simulated continuous fabric bleaching. Saturate a dry pure cotton fabric with bleach solution (300mf2 Approximately 8 g of fabric was wrung out uniformly in the bath and placed in a carrier previously brought to the experimental temperature.

The carrier was supplied with water vapor and oxygen in Experiments B and C, and only water vapor was supplied in Experiment A.

The air was opened to the chamber via a valve. The experimental temperature in the carrier was 9 in all experiments. The temperature was 3°C. After 30 minutes, when bleaching is complete, open the container and remove the sample for washing. The whiteness taken out and shown in Table 7 was measured as a CIE index without using UV light. The starting whiteness is subtracted from the maximum whiteness. The results are shown in Table 7.

Table 7. Whiteness A as CIE index for bleached fabrics 10 11.27 Air 47.68 BO11,28 Oxygen 2.74 C1011,30 oxygen 54.87 (*) Subtract the starting brightness from the final brightness.

Table 7 shows that the whiteness obtained in experiment The is greater than the sum of the whiteness for experiments kA and B. It clearly shows that.

Example 9 These experiments for bleaching cotton were performed in the presence of oxygen and in the absence of oxygen. Reduced hydrogen peroxide, caustic and stabilizer consumption while achieving greater whiteness I went there to show how small it is. These experiments were conducted in the vapor phase in a steam box. bleach solution in all experiments. The pH was 1017-10.0. The pressure is slightly greater than atmospheric pressure, creating a water vapor bomb. The temperature in the box was 93°C. Bleaching time was 30 minutes. Whiteness, UV The CIE index not used is the final brightness minus the starting brightness.

Table 8. Whiteness as CIE index for bleached fabric 18.4 8. 4 14.0 57.8, 57.312, 9 6.7 14 ．． 0 60.0.59.312.9 6.7 11. 2 58.512, 9 6.7 8.4 58.411.0 5.0 14.0 59.2 Table 8 shows that when oxygen is present instead of air, the amount of hydrogen peroxide can be reduced. Example 10 that proves that it can be reduced by at least 40% The following experiments were carried out to demonstrate that faster bleaching can be achieved.

The bleaching solution was 37.5 g/J2 hydrogen peroxide, 7.0 g/I2 sodium hydroxide. and 30 g/β of stabilizer. The pH of this bleaching solution is 1017~1 It was 0.8.

These experiments simulated continuous fabric bleaching. Saturate a dry cotton fabric with bleach solution and It was squeezed out and then placed in a steam box. The temperature inside the steam box is 93℃. However, the pressure of water vapor and gas (nitrogen or oxygen) was slightly higher than atmospheric pressure. sample were taken from the steam box at regular time intervals of 5 minutes. The sample was washed and dried After-whiteness was evaluated.

Results are shown as a function of bleaching time using nitrogen and oxygen atmospheres as the gas phase, respectively. Figure 8 shows the CIE index without using whiteness and u.

Example 11 In this example, the amount of hydrogen peroxide used on the desized fabric was reduced when oxygen was added. This shows that it can be reduced. Because it is a continuous fabric, this is a saturator and A very similar bleaching using a J-box carrier was performed. However, the bath liquid is different. Ru. Oxygen was added in the same manner as in bleaching and the results are shown in Table 9.

1 1.7 12.65 Air 45.18 1.372 1.0 12.65 Oxygen 48.21 1.34 Extract is the amount of glue left on the fabric Measure. Experiment 1 shows standard plant operation and results, Experiment & 2 shows on fabric While leaving the same amount of extract, a reduced amount (1°Og/l instead of 1,7g/β) can be used and has been shown to produce better whiteness.

using oxygen gas in an alkaline solution in combination with a common bleaching agent such as hydrogen peroxide The resulting whiteness of the bleached yarn or fabric was unexpected. Muell er proposed the use of molecular oxygen over 70 years ago, but his method has never been used. No, most products currently contain cotton fibers or in blends with other fibers. are bleached with hydrogen peroxide, Mueller said, to enhance the bleaching reaction. Therefore, we proposed the use of heavy metal ion compounds as catalysts.

Those skilled in the art will recognize that the partitioning of peroxide into water and oxygen is a deleterious reaction that must be avoided. Consider the solution. In many bleaching methods, the amount of hydrogen peroxide added is The amount of oxygen formed when the bulk decomposes is so large that it cannot be retained in the liquid.

Despite this fact, no bleaching effect of oxygen was observed. On the contrary, Oxygen produced by decomposition of hydrogen oxide is inert and does not have any bleaching effect. There is a statement in the literature that states that.

The results obtained with the present invention are excellent; two agents, oxygen and hydrogen peroxide, It is believed to act in a catalytic manner. Excellent results show synergistic effects, second bleaching Since the amount of hydrogen peroxide can be reduced by using oxygen as an agent, Other advantages besides lower bleaching costs are obvious. Chelating agents and sodium The amount of stabilizers such as silicate compounds can be reduced or omitted. mosquito Since such drugs are mostly transported to the receptors, such a reduction in drugs has a positive impact on the environment. have Furthermore, the use of less silicate gives the bleached fabric a good hand.

It also allows bleaching at low pH values. Furthermore, it is necessary to reach a certain pH value. The amount of hydroxide ions is found to be lower when the concentration of peroxide ions and stabilizers is lower. Served.

According to the observations of the present inventors, optical brighteners when used on oxygen-bleached yarns or fabrics This is considered to indicate that there is a kind of promoting effect on constant white color The amount necessary to reach a Less than in the case.

Oxygen is present in the gas phase when cotton-containing products are wetted with alkaline solutions. It is also an active bleaching agent when applied to products. Oxygen is present in alkaline solutions as bubbles. It can also be applied to products containing moistened cotton fibers. Contained in gas phase or bubbles When bleaching is carried out on wet fabrics using oxygen in a concentrated form, a large amount of liquid phase is present. There is no need to

Flg, 5 June 19, 1990 I. Patent application number PCT/SE　88100685 2. Name of the invention How to bleach cotton 3. Patent applicant Name: Nydayny Aktivolag representative: Weedman, Bernd GB 2214 discloses that the material to be treated is first boiled and washed. A bleaching method is taught in which the colorant is fully reduced and broken up. When the material is removed, the material is exposed to the action of ozone while being heated. Then add about 2 ingredients Immerse in a chlorine bath of normal character and concentration for ~12 hours. Next, wash the material and then Let it be subjected to the action of a chlorine remover. Immerse it in a weak alkaline solution before ozonation. Good too.

1 and 1 The purpose of this invention is to greatly reduce the amount of conventional bleaching agents and to improve the quality of products containing cotton fibers. Bleaching has high whiteness and absorption power.

Another object of the invention is to use oxygen alone or conventional bleaching agents such as hydrogen peroxide or hypochlorite. Products with a higher degree of whiteness than conventionally obtained by using sodium chloride alone. It's all about bleaching.

Yet another object of the invention is to provide rapid bleaching with hydrogen peroxide to a certain degree of brightness. There are many things.

Yet another object of the invention is to use adjuvants such as optical brighteners and stabilizers in bleaching processes. The goal is to reduce the amount.

Another purpose is to avoid spills when using sodium hypochlorite in bleaching cotton-containing products. The purpose is to reduce the amount of chlorine chemicals in the liquid.

1. The present invention The product is treated with an alkaline solution in an alkaline bleaching step and with another treatment prior to the bleaching step. stage and with the alkaline liquor of another processing stage following the bleaching stage. contact; use hypochlorite or hydrogen peroxide as a conventional bleaching agent in the bleaching step. :and said alkaline treatment step of another alkaline treatment step preceding or following said bleaching step. Oxygen-containing gas is added to the processing solution and/or the alkaline processing solution of the alkaline bleaching solution in the bleaching stage. introduce The present invention relates to a method for bleaching products containing cotton fibers.

Furthermore, the present invention provides products with an oxygen-containing gas dissolved or dispersed in an alkaline processing solution at high temperatures. The purpose is to bleach products containing cotton fibers by exposing them to the action of water. oxygen containing gas is at least 50% oxygen, preferably at least 99% oxygen, i.e. pure oxygen Consists of gas. The remainder of the gas is an inert gas such as nitrogen or a noble gas. this oxygen Gas treatment involves an alkaline treatment stage in the absence of conventional bleaching agents such as hydrogen peroxide. It can be done on the floor. Oxygen gas is supported as much as possible by agitation of the liquid; This ensures that the liquid is as evenly distributed as possible to avoid collecting dissolved oxygen on top of the liquid in the container. The gas is dissolved or drifted into the processing liquid by means of a blowout device that disperses or spreads the gas. Oxygen is introduced into the headspace of the expansion vessel or processing vessel of the white equipment, and the oxygen gas is In order to dissolve or entrain, the processing liquid is stirred and dissolved in the processing liquid. conventional bleach After such treatment with oxygen gas in the absence of bleach, the product preferably contains hydrogen peroxide. Alkaline processing using oxygen gas is carried out in an alkaline bleaching solution containing , a scouring stage after enzymatic desizing, or an alkaline desizing and scouring step. It can be a combination stage of training.

According to another preferred embodiment, the treatment with oxygen gas in alkaline liquid In this embodiment, conventional desizing is carried out in the presence of The bleaching stage and conventional scouring stage can be carried out prior to the bleaching stage, or can be carried out simultaneously. For certain applications and quality requirements, one or both of these traditional pretreatment steps can be omitted. Can be omitted.

According to yet another embodiment, the product is suitable for bleaching in the absence or presence of bleaching agents. After the step, it can be subjected to the action of oxygen. The necessary conditions are high temperature treatment with oxygen. This is done in an alkaline solution.

Yet another embodiment comprises the use of ozone in the form of a mixture with an oxygen-containing gas. , in which part of the oxygen and inert gas is replaced by ozone. Ozone concentration is typical can range from about 6% to about 0.5%.

The scope of the claims ■、Products containing cotton fibers are bleached with alkaline solution in the alkaline bleaching stage. with an alkaline processing solution in another treatment step preceding the step and another treatment following the bleaching step. in close contact with the alkaline liquid of the stage, Using hydrogen peroxide or hypochlorite as a regular bleaching agent in the bleaching step A method for bleaching a product containing cotton fibers, which comprises a step or step prior to said bleaching step. The alkaline processing solution and/or the bleaching step followed by another alkaline processing step. Introducing an oxygen-containing gas into the alkaline processing solution of the alkaline bleaching solution How to characterize it.

2. Introduce the oxygen-containing gas into the processing container containing the processing liquid and use the injection means to be dissolved in the processing solution or introduced into the headspace of the container to agitate or circulate the solution. 2. The method of claim 1, wherein the ring dissolves in the processing liquid.

3. Recirculate the processing liquid to the expansion container and recirculate the oxygen-containing gas by means of injection. into an expansion vessel containing the treated liquid and dissolve it therein, or into the processing liquid by stirring or circulating the liquid. The method according to claim 1, wherein the method is dissolved.

4. Introducing oxygen-containing gas into the processing container containing the product moistened with the alkaline processing liquid. 2. The method of claim 1, wherein oxygen is diffused into the liquid layer of the wet fibers.

5. The oxygen-containing gas contains at least 50% by volume of oxygen, preferably at least 99% by volume of oxygen. 5. A method according to any one of claims 1 to 4, comprising % by volume of oxygen.

6. Claims 1 to 4 in which the oxygen-containing gas contains 6% by volume or less of ozone The method described in any of the paragraphs.

7. The temperature of the processing liquid containing dissolved oxygen gas is in the range of about 80 to about 130 °C, Any one of claims 1 to 6, preferably in the range of about 75 to about 115°C. Method 8 described in range from about 9 to about 13.7, preferably when containing hydrogen peroxide as a conventional bleaching agent. ranges from about 10 to about 12, and when the processing solution does not contain conventional bleach, about 1 3 and about 13.5. .

9. Time for processing the product in alkaline liquid containing dissolved oxygen gas is in the range of about 10 to about 200 minutes, preferably in the range of about 15 to about 60 minutes. The method according to any one of items 1 to 8.

10. The bath ratio (fiber to liquid) of the treatment liquid containing oxygen gas is about 1:1 to about 1:50. Claims 1 to 9, preferably in the range of about 1:1 to about 1:10. The method described in any of the above.

11. Oxygen partial pressure in the container supplying oxygen-containing gas is about 0.1 to about 1. OMP Claim 2, which is in the range of a, preferably in the range of about 0.1 to about 0.6 MPa. Method 12 according to any one of items 1 to 4, supplying an oxygen-containing gas in the bleaching stage, Any one of claims 2 to 11, wherein hydrogen peroxide is used as a common bleaching agent. The method described in.

13. Claim No. 1 in which an optical brightener is added to a bleaching solution containing a normal bleaching agent. The method according to any one of Items 1 to 12.

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Claims (17)

[Claims] 1. Wood, preferably in the form of filaments, threads, crocheted, knitted and woven fabrics Bleaching of cotton fibers and products containing such fibers in the form of blends with other types of fibers In the method, the bleaching step is preceded or followed by another alkaline treatment step and/or Introducing oxygen-containing gas into the alkaline processing solution in the alkaline bleaching stage, if necessary Also, do not allow the product to come into close contact with said alkaline processing liquid containing dissolved oxygen gas. A method characterized by: 2. Using hydrogen peroxide or hypochlorite as a conventional bleaching agent in the bleaching step The method according to claim 1. 3. An oxygen-containing gas is introduced into a processing container containing a processing liquid and is Dissolved in the processing liquid or introduced into the headspace of the vessel to facilitate liquid circulation or The method according to claim 1 or 2, wherein: is dissolved in the processing liquid by stirring. . 4. The process liquid is recirculated to the expansion vessel and the oxygen-containing gas is recirculated to the chamber containing the recycled process liquid. into an expansion vessel and dissolve therein by injection means, or into the expansion vessel. The solution is introduced into the head space and dissolved in the processing solution by circulating or stirring the solution. The method according to claim 1 or 2. 5. Oxygen-containing gas is introduced into the processing vessel containing the product moistened with an alkaline processing liquid. According to claim 1 or 2, in which oxygen is introduced and diffused into the liquid layer of the wet fibers. the method of. 6. The oxygen-containing gas contains at least 50% oxygen by volume, preferably at least 99% oxygen by volume. 6. A method according to any one of claims 1 to 5, comprising % by volume of oxygen. 7. Any of claims 1 to 5, wherein the oxygen gas contains 6% by volume or less of ozone. The method described in 8. The temperature of the treatment liquid containing dissolved oxygen gas is in the range of about 80 to about 130 °C, Any one of claims 1 to 7, preferably in the range of about 75 to about 115°C. The method described in. 9. The pH of the treatment solution containing dissolved oxygen gas is higher than that of the treatment solution as a normal bleaching agent. In the range of about 9 to about 13.7, preferably about 10 to about 12 when containing hydrogen peroxide. and should be in the range of about 13 to about 13.5 when the processing solution includes conventional bleach. The method according to any one of claims 1 to 8. 10. Time for processing of products in alkaline liquid containing dissolved oxygen gas is in the range of about 10 to about 200 minutes, preferably in the range of about 15 to about 60 minutes. The method according to any one of items 1 to 9. 11. The bath ratio (fiber to liquid) of the treatment liquid containing oxygen gas is about 1:1 to about 1:50. range, preferably from about 1:1 to about 1:10. The method described in any of the paragraphs. 12. The oxygen partial pressure in the container supplying the oxygen-containing gas is about 0.1 to about 1.0 MPa from about 0.1 to about 0.6 MPa, preferably from about 0.1 to about 0.6 MPa. The method described in any of Section 5. 13. Supplying oxygen-containing gas to the bleaching stage and using hydrogen peroxide as a regular cleaning agent The method according to any one of claims 2 to 12. 14. Claim 1: The optical brightener is added to a bleaching solution containing a conventional bleaching agent. ~The method according to any one of Item 13. 15. Claims that the oxygen-containing gas is introduced continuously or intermittently during the processing stage The method according to any one of items 1 to 14. 16. Continuously or intermittently feeding product into or removing it from a processing stage The method according to any one of claims 1 to 15. 17. Cotton, preferably in filament, thread, crocheted, knitted and woven form in fibers and textile products containing such fibers in the form of blends with other types of fibers. , a textile product characterized in that it has been bleached with oxygen and ordinary bleaching agents.