DE1444012A1 - Process for bleaching cellulose fibers - Google Patents

Description

PATENT LAWYERS

TELEGRAMS: ZUMPAT SMdNOHEN 2, POST CHECK ACCOUNT: MÖNCHEN QI ₁₃₉ BRÄUHAUSSTRASSE

BANK ACCOUNT: BANK H. HOUSES

JtV / lio CL. 1324

Corporation, H <ro York 17, H.Y.

-art ^ r * * ifl * «M Τ ^ ΐ ^ * ΐ5? ■■■ ΐ ^ ΊΕ ΐΐΐ ΙΤ ^ ΐ # ^ ΐ «* ¥ - * ΐν» 3 * · 4 ΐ-ΐ »^ ^- Ξ: J ^ J ^ ^ Γ ^ Ll-"? ^ I ia T ί ί? mm τ '"ΐ Γ5 5 ^^ 2

Process for bleaching cellulose fiber ^

JPlaying invention relates to a method sium continuous .Βλeichen of gray, gev / obtcm BaumwolltexMlien, particularly * oondere degreasing and BIS1, efi? £ mvoiv Bauta'w ^ lltextilien in a single treatment o "gaatme _t. how-a · B. a «! ·. . J-shaped chamber, for the vriimufig von.-Been with high prieiction ability una good oaugrani |: ke _r i-fc ■ »... '" * -

Wh biuher usual Bleiohvor ** !. u>h'iungen require at least siv "ii treatment zones or J! 'Ownlge chambers as να * satisfactory' Vice end bleach" / cn Bfmmwollfaserne Here, the beaming ha ηαο, Υι is the Kntfernung of Textilappretui 'en dur «h iviia./inbehandlvn?- ottor arulex ^a e Entochlichtmigsver-

drive in olnenNa'ironlauge an'Am . "M; end saturator directed,

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where 88 absorbs a certain amount of solution. The cloth saturated with caustic soda is then fed to a first J-shaped chamber for% ut degreasing, where it is heated to about 100 ° G (212 ° F) for 30 ~ 90 minutes. This Ätznatronentfettirag conditions the TUEH for further assistance "" lung by opening Stäubohen and durcsh Yerbesaerung the absorbency of Celluloseinaterials _o Yienn the search from the first J-shaped chamber comes out - _t e © siir remove residual sodium hydroxide solution washed and übmu in Einesi -second V / asa first of fperoxydllf solution containing en saturator "directed Bas with WaaaerstoffperoxydlöaiiBg ge · = aättlgt® TUEH is uwl äann passed to a second J = i * Srmige laiaiiei ^ä or aweite BehandHungssone * sum Pale! dea Sueiies directly with steam (150-210 ° F) to about 56 = · 99 G heated If "iaa fueh Tom bottom of the J =?" shaped chamber is removed, it becomes a residual chemicals gewaselisn wziü GSTI ^c oeknet = the remains 30 = 90 minutes.. in Jedor Eehaadliangsaoaej, i.e. in every uniform chamber »

It is favorable to the number of retention zones

so that only a J-shaped chamber or BshaxMÖ.unga ^ on degreasing and lead is required, oJm © the Ifeity ₉ ie the reflection or the absorbency of the "bleached" stitches, UIe is a measure for this ₉ as dae cotton fabric with NEN solutions such as s. B. ¥ on dyes and andsren

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agents, soaked and wetted. the The difficulty in combining degreasing with strong lye and bleaching consists in the fact that the water » etoffperoxyd decomposed in the bleaching solution in the presence of highly concentrated batron lye. So far it has not been Process described that involves the stage of degreasing strong liquor and the bleaching stage in a single treatment zone united.

Various attempts have been made to get the number to reduce the treatment stages, e.g. £. by the cloth wetted with a single weakly alkaline peroxide solution, then passed into a J-shaped chamber and steamed is treated. In this, for. Methods described in U.S. Patents 2,257,716 and 2,868,615 the usual degreasing with concentrated lye is omitted. Another method in which the number of treatment steps is reduced is in the United States patent letter 2 858 183, the cloth being saturated in a mixture of a surfactant and a phosphate, then passed into a saturator containing alkaline peroxide and finally to the steam treatment is passed into a J-shaped chamber. In this process too, degreasing with strong lye is omitted «

These processes were not found to be completely satisfactory because they use the strongly alkaline ent- ■. 309810/0723

fat bath of the above 2-step process by a weakly alkaline peroxide solution is replaced; the finished The product has unfavorable physical properties, i.e. lower absorbency and poor adhesive properties «

The aim of the invention is to develop a method for bleaching cotton fabrics, degreasing with strong lye and bleaching in a single treatment aone or J-shaped chamber, whereby one a bleached! cloth with high reflection, good absorbency - ** ability and favorable coloring properties »

According to the invention, desized gray cotton fabric is bleached by passing the cloth into a solution containing about 1.5 to about 5.0 wt single treatment zone, heated for 15-45 minutes at one end of the treatment zone to about 93-100 ° C (200-212 ° P), the cloth containing the alkaline solution is passed directly into an aqueous hydrogen peroxide solution, which is located at the other end of the treatment zone is located, the Tuoh is heated for about 15-45 minutes at about 66-99 ⁰ c (150-210 ° F) in the aqueous water-Btoffperoxidlösung and the concentration of the alkali hydroxide in the hydrogen peroxide solution at about 1.0 to about 1.5 wt. »56 is held.

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It is very surprising that the one compares A cloth containing a high percentage of alkali hydroxide is passed into the hydrogen peroxide solution in this process can be without causing a substantial premature decomposition of the hydrogen peroxide solution. Highly concentrated Cloths containing alkali hydroxide are generally washed first to remove the hydroxide and only then Washed alkali-free cloth is fed into the hydrogen peroxide bath

In the above procedure, this intermediate washing step was found not to be necessary as it does not include everything Alkali hydroxide on the cloth as a result of the strong affinity of the cellulose for alkali hydroxides in the bleaching solution is dispersed. In addition, it is in the hydrogen peroxide bath existing amount of alkali hydroxide due to the necessary continuous addition of fresh water offperoxydiasung to the peroxycibad to adjust the peroxide content of the bleach bath regulated to the desired concentration »An overflow opening holds the hydrogen peroxide * quantity in the bathroom constant

The expression "single trading zone" means a single one Understand step of continuous treatment of the fabric, this is temporarily stopped. That Procedure is generally in a single J-shaped Chamber or a similar device executed, wherein

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The cloth in the chamber is piled up by the cloth brought at constant speed into the upper part of the J-shaped chamber and there, at the other end with handy the same speed is removed.

In this process, the cotton fabric becomes a common one Subjected to sizing removal treatment when it is finished with a finish or surface finish. Treated to do this, the cloth generally with a conventional aqueous enzyme solution and then washes it to remove the Size in its converted water-soluble form with water. If no finish or surface finishing is available the cloth does not need to be treated like this.

The cotton fabric freed from textile finishes is then passed into a saturator containing an alkaline solution, where it absorbs 50-150% by weight of the solution, based on its weight. This bath must be at least about 1.5 but not more than about 5.0 wt. 3 & alkali hydroxide, such as. B. NaOH or KOH contain. Lower concentrations than about 1.5 i * alkali hydroxide not degrease the tissue in a suitable manner, wähKnfl: "fcärkere concentrations ale about 5 '0 are to be avoided because they are not better degrease and increase Alkalihydroxydkonzentration in the bleach solution over the value addition in where the solutions are stable "

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The cloth saturated with alkali solution is then placed in the top of a single treatment zone or J-shaped chamber. In the upper part of the J-shaped chamber, the cloth is treated with steam at around 93-100 ° C (200-212 ° P). In some cases, the temperature eteigt than 100 ° C (212 ° P), since the densely packed Tu ^ h the top T _e il of the J-shaped chamber lock and can thereby prevent the water vapor escapes. The cloth is treated at this temperature for about 15-45 minutes, depending on the required degreasing of the cloth. Subsequently, the oil, which is still saturated with alkali solution, is passed directly into a hydrogen peroxide bleaching solution without washing in between.

The bleach bath preferably consists of a solution of Hydrogen peroxide in water. Ee is abor in the range of Invention, solutions of other equivalent Psroxydverbindungen such. B. of alkali monoper sulfate esa, X'eroxydisulfaten, Perborates and hydrogen peroxyo addition

apply / connections, such as B. Ha ₂ CO _; · H ₂ O ₂ ^ _n Strongly alkaline peroxide compounds, such as. B. Ua ₀ O ₀ are not beneficial and should not be used.

The hydrogen peroxide bleach solution is set to about 66 - 99 ° C (150 - 210 ° P) and is most appropriate in the U-shaped part of the J-föiTnigftn Kararaer. The cloth stays t; about 15 ~ 45 minutes, depending on aej. öx \ necessary bleaching,

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in the hydrogen peroxide solution. ! If the hydroxide impregnated with alkali "cloth moved in the bleaching solution down solves some verifiable on the cloth hydroxide present in the Wasserstoffperoxydbleiche to _0. The remaining hydroxide remains in the bleached cloth and passes through the hydrogen peroxydbleichlusuiig; outside the J-shaped chamber, it is washed out with water

The hydrogen peroxide bleach bath must contain about 1.0 = 1.5 wt .-> δ alkali hydroxide. When the amount of alkali hydroxide falls below about T ₉ O #, the alkalinity of the hydrogen peroxide bleach solution falls below that required for effective bleaching of the hydrogen peroxide solution present. Amount, On the other hand, if the amount of alkali hydroxide exceeds about 1.5 #, the alkalinity will exceed the amount that can be tolerated in the hydrogen peroxide solution without causing excessive hydrogen peroxide decomposition.

The alkali hydroxide concentration in the hydrogen peroxide bleaching solution is regulated by adding fresh hydrogen peroxide to the solution at such a rate and in such a concentration that the amount of alkali hydroxide in the bath remains as high as one wishes and that the peroxide used up during bleaching is replenished These two goals are generally achieved by adding a 1.75 ml of hydrogen peroxide supplement to the bleach bath.

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solution admits. The hydrogen peroxide bleaching solution is kept constant in the U-shaped part of the J-shaped chamber by means of an overflow opening. Excess used lead cavity is continuously removed through this opening and discarded. The opening is preferably located at a location remote from that at which the hydrogen peroxide replenisher is in the J-förraige chamber to the Wasserstoffperoxydverlust in the waste liquor as low as possible to keep ₀ The exact arrangement ä & T opening for the bleaching solution supplement and the overflow opening can be selected to give optimum results with the tissue and bleaching solution used. It is generally beneficial to use a recirculation system so that the amount of peroxide in the treatment solution remains the same.

Me hydrogen peroxide bleaching solution should contain at least about 0.7 Ί » hydrogen peroxide, so that a favorable white content is achieved. Bleach solutions containing from about $ 0.7 to about $ 1.75 hydrogen peroxide have been found to be beneficial. The stability of the hydrogen peroxide solution is increased by the addition of about t to about 3 wt .- # of soluble silicate salt, such as. B. sodium silicate improved. If desired, other known means of the hydrogen peroxide solution can be used directly or the

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position of the hydrogen peroxide solution used water can be added so that the solution has favorable wetting properties or to remove interfering metal ions in the tissue or in the water by complex formation. You can z. B. tetrasodium pyrophosphate, Versenex 80 (a pentasodium salt of diethylenetriaminepentaacetic acid), Epsom salt and ißergitol MPX C a non-ionic alkylphenyl polyethylene glycol ether « add wetting agent »

In the method according to the invention, the degreasing with alkali is carried out by treating the cloth impregnated with an alkaline solution with water vapor. The subsequent bleaching, on the other hand, is not carried out by steam treatment, but is more closely related to a continuous boiling treatment, namely in that the cloth is treated while it is immersed in a hot, aqueous hydrogen peroxide solution? hat is not saturated with hydrogen peroxide solution and then treated with steam »The method according to the invention thus combines an effective degreasing treatment with strong alkali with continuous cooking bleaching in a single J-shaped chamber results, which gives the bleached cloth an extraordinary absorbency and smooths an excellent coloration in the following process steps. . ao 981-0 / 0 72 3

In the attached flow sheet, the following are described chemical and physical process steps explained. The drawing explains the invention without it to restrict.

1 represents a cloth wurdeα treated to remove primers or Zurichtungemitteln The cloth is fed into a Laugeneättiger 2 where it is with 50 - 150 l of "his Gewiohts to 2 - 5 is impregnated #iger sodium hydroxide solution (Kaoh) ,. The cloth impregnated with caustic soda is then conducted into the upper part of a J-shaped chamber 3 / from an inlet opening 4 through the lines 5 into the openings 6 of the J-shaped chamber. The cloth is steamed as it is slowly passed through the top of the J-shaped chamber for 15-45 minutes. After the steam treatment in the upper part of the J-shaped chamber, the cloth is passed down through the U-shaped part of the J-shaped chamber and sprayed through the spray heads 11 with a mixture of fresh hydrogen peroxide solution and circulating hydrogen peroxide solution. The fresh additional hydrogen peroxide solution from the container 7 is introduced through the line 8 and mixed with the circulating hydrogen peroxide fed through the line 14. This mixture flows through lines 9 and 10 and is sprayed through the spray heads 11 into the J-shaped chamber.

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solution directed · A collecting trough 12 removes the YfäsBerstoffperöxyd from the bottom of the J-shaped chamber and "directs" it through line 13 to heater 17. The heat exchanger is heated with water vapor from line 4 and the water vapor is removed through line 18. The through the Line 13 in the heat exchanger 17 conducted hydrogen peroxide bleach solution Is heated to about 82 ° 0 (180 ° P) and brought through line 14 into line 8 to it with fresh hydrogen peroxide substitute solution from the container 7 au mix · Excess solution that does not contain hydrogen peroxide Contains more is than waste solution through the mouth / 15 removes the point of entry of the hydrogen peroxide solution opposite? the used solution, which contains only a small amount of hydrogen peroxide, will be so removed. The opening 15 also regulates the level 16 of the hydrogen peroxide bleach solution located in the J-shaped chamber; the excess is discharged through line 21. The tissue exits the J-shaped chamber the outlet opening 19 is clean and bleached and is then used to remove residual alkaline hydrogen peroxide and other chemicals in a water scrubber 20 directed

The following examples illustrate the invention without restricting it.

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Example 1s

Bauia wool fabric with 31.5 x 30.7 threads / cm (80 χ 78 threads / ineh) and about 10.1 m / kg (weighing about 5 yards per pound), which is free of sizing, is saturated with an aqueous solution, enthä3.t the 3.0 wt .- S sodium hydroxide solution, 0.3 i * tetrasodium pyrophosphate and 0.1 # Tergitol NPX and at 77 82 ° C? (170-180 ° F) wiröo held Man the cloth can absorb as much solution as corresponds to about 100 fo of its weight. The cloth is then passed into the straight section of a J-shaped chamber and steamed for 25 minutes at about 100 ° C (212 ° F). After the steam treatment, the unwashed cloth is passed into the curved section of the J-shaped chamber, which contains a bleach solution with the following ingredients! 1.05 # hydrogen peroxide, 2.0 fo sodium silicate, 0 _s 3 # tetrasodium pyrophosphate, 1.0 $> sodium hydroxide solution, 0 _s 1? S Vereenex 80, 0.1 # Epsom salt and 0.1 f Tergitol NPX. 3> B ^ ie iehlösung is at 77 - held - 82 ° C (180 ° F 170). The tissue is passed through the J-hair dryer chamber at such a rate that it remains in the bleach solution for about 35 minutes; Then it is washed and dried. The bleaching solution is kept at the bottom of the J-shaped chamber at a content of 1.0 # sodium hydroxide solution, in which hydrogen peroxide additive liquid contains 1.75 ° ß> hydrogen peroxide, at a rate of 1 .14 liters (0.3 gallons) per minute is discharged «bas of bleached cloth

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is then tested for reflectivity (whiteness) with a Hunter Lab reflectometer., A high value indicates high reflection and good bleaching, _a values above 82 $> bind generally sufficient.

The mobility (fluidity) of the bleached tissue becomes tested according to the procedure of the American Association of Textile Chemists and Goloriste Tentative Test Method 82-1954, using copper ammonium hydroxide «This The test is used to determine if the fiber has been damaged after bleaching. A high value indicates great damage at. Values below 10 show no excessive chemical damage to the cellulose and are generally sufficient »

Bleached fabric absorbency is determined by the American Association's Tentative Test Method 79 ~ 1954 of Textile Chemists and Colorists »This experiment is used to determine the time it takes for a certain amount of water required by the cloth Large values indicate low absorbency Values below 2 are sufficient =,

Ea was found to have reflectivity in the fabric of 87.1 # 9 an agility of 2.8 and one Has absorbency of 0.9 seconds.

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After de "washing and drying the bleached search is dyed in a continuous dyeing apparatus with a blue vat dye * _t if the fabric has this dyeing process and the color Bind βehr sensitive to bad bleached tissue and give poor results no good absorbency and other favorable dyeing properties. The result is excellent over the entire length of the fabric, everything is dyed evenly and no stains or other staining defects remain.

Example 2:

Cotton fabrics with 31.5 x 30.7 threads / cm (80 χ 78 pads / inch) and 10.1 m / kg (weighing from 5 yards per pound), free of size, are saturated with an aqueous solution that contains 1 Contains 5 ßewo-ji sodium hydroxide and 0.1 # Tergitol HPX; the solution is held at 77-82 ° C (170-180 °?). The tissue is allowed to absorb as much solution as corresponds to about 100 $ of its weight. The tissue is then passed into the straight section of a J-shaped chamber and treated with steam for about 25 minutes at about 100 ° C (212 ° P), ^ After the steam treatment, the unwashed fabric is fed into the curved section of a J-shaped chamber that contains a bleaching solution with the following ingredients? 1.05 # hydrogen peroxide »2.0 # sodium silicate, 0., 3 # tetrasodium pyrophosphate, ip $> sodium hydroxide solution 0.1 $ ¥ ereenej: 8O ₁ , 0.1 56 Epsom salt and 0.1 # Tergitol HPX ₀ The bleaching solution will

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held at 77-2 ° C (170-180 ° 3?). The tissue is passed through the J-shaped chamber at such a speed that it remains in the bleach for about 35 minutes; it is then washed and dried. The bleaching solution at the bottom of the J-shaped chamber is kept at a content of 1.0 # sodium hydroxide solution by adding a hydrogen peroxide solution with a content of 1.75 $ hydrogen peroxide at a rate of -1.14 liters (0 _# 3 gallons) per minute. The bleached cloth is then tested for reflectivity, mobility and absorbency in the manner described in Example 1. The fabric has a reflectivity of 86.8 Ji, a mobility of 2.7 and an absorbency of 0.8 Seconds.

Example ? T

Cotton fabric with 31.5 x 30.7 threads / em (80 χ 78 threads / inch) and about 10 »1 m / kg (5 yards per pound), free of size, is saturated with an" aqueous solution that is 3 » Contains 0% by weight of sodium hydroxide, 0.6 $ tetrasodium pyrophosphate and 0.1 $> Tergitol KPX and is kept at 77-82 ° C (170-180 ° F). The tissue is allowed to take up as much solution as about 100 # "The tissue is then passed into the straight section of a J" shaped chamber and steamed at about 100 ° C (212 ° F) for about 25 minutes

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The unwashed fabric is passed into the curved section of a J-ft-shaped chamber containing a bleach solution bit the following: 1.05 5 & hydrogen peroxide, 2.0 # sodium silicate, 0.3 $> tetrasodium pyrophosphate, 1.0% sodium hydroxide, 0 , 1 # Versenex 80, 0.1 i * bitter eels and 0.1 j6 Tergitol NPX. The bleach solution is held at 77-82 ° C (170-180 ° P), the tissue is then passed through the J-shaped chamber at such a rate that it remains in the bleach for about 35 minutes; It is then washed and dried "The bleaching solution at the bottom of the J-shaped chamber is prepared by adding Wasseretoffperexydzusatzflüssigkeit, ÖIE 1.75 $ hydrogen peroxide includes, at a rate of 1.14 liters (0.3 gallons) per minute to a content of 1.0 # sodium hydroxide solution held. Dam bleached fabric is then tested for reflectivity, mobility and absorbency in the manner described in Example 1. The fabric has a reflectivity of $ 84.6> a mobility of 6.3 and an absorbency of 0.9 seconds.

The method according to the invention is favorable because only one single J-shaped chamber is required to degrease alkaline au and bleach well. The result is therefore less time aura degreasing and bleaching of a certain amount of tissue is needed and smaller amounts of tissue are involved bound by the procedure. Bs is cheap, the amount of

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to reduce tissue bound in the process, so that Procedural changes can be implemented more quickly, without the need to process large amounts of tissue <> So you get better adaptability α

While at the moment 2 or more J-shaped chambers for using separate degreasing and bleaching allows the method of the invention to be used from each J-shaped chamber to a separate and full » constant bleaching process Thus, the amount of tissue treated can be almost doubled, and each J-shaped chamber can be used for the Bleaching of a different type of fabric or quantity that requires other bleaching processes can be used «,

The method according to the invention differs advantageously from the usual peroxide dipping and steam bleaching process; the bleach will be at the bottom of the J-shaped chamber carried out in a continuous cooking process. Instead of putting the tissue in a hydrogen peroxide solution dip, and then steam the fabric saturated with the bleaching solution, the fabric is bleached by placing it in one during the entire bleaching process hot, aqueous hydrogen peroxide solution is immersed. This continuous Koohbleiohe creates a fabric with

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high absorbency and very good dyeing properties · JHe Improved dyeing properties are likely to be due to the fact that the fabric is completely immersed in the bleaching solution is saturated. Both the absorbency and the coloring properties of the according to the invention Processes of treated tissue proved excellent and not just superficial, as with many Bleaching process in which immersion is carried out in a peroxide solution and then treated with steam.

The method of the invention is also more effective in Utilization of chemical additives »In particular, the Alkaline solution applied to the fabric during degreasing at about 1? & Lger concentration in the bleaching solution and kept at this concentration · So there is no need to add alkali hydroxide to the bleach solution EU will be to the desired alkali content in the hydrogen peroxide bleach solution to maintain. For other processes in which degreasing and bleaching are carried out separately, the degreased tissue is washed free of caustic soda before the hydrogen peroxide lead solution is applied; the hydroxide solution must therefore be used separately for degreasing and added to the bleach solution. In the process according to the invention, this double addition of caustic soda is not an option necessary"

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3Dae according to the method is therefore also advantageous » adherent because the hydrogen peroxide solution at the bottom of the J-shaped chamber is lifted up by the tissue and as a lubricant between the tissue and the walls of the J-shaped chamber acts. The tissue is therefore through the U-shaped part of the J-shaped chamber passed through with very little confusion owing to the dilution effect the hydrogen peroxide solution also many undesirable crusts, such as. B * silica and others added Chemicals, removed, as these compounds are soluble in the aqueous solution.

The method according to the invention is also advantageous in that, after the lead has ended, the tissue is less needs to be washed. 3> as is based on the washing effect of the hydrogen peroxide solution when the fabric is through the J-shaped chamber flows. Lots of impurities that are difficult to remove with a single steam treatment are therefore easily removed when the tissue is in the hot hydrogen peroxide solution on the ground the J-shaped chamber is soaked for a long time

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Claims (1)

H44012 1 · Process for bleaching desiccated gray cotton fabric, characterized in that the fabric is passed into an approximately 1.5 - approximately 5 wt Cloth passed into a single treatment zone, heated to about 93-100 ° C (200-212 ° P) for 15-45 minutes on one of the treatment zones, the cloth containing the alkaline solution is passed directly into an aqueous hydrogen peroxide solution, which is is at the other end of the treatment zone, the cloth is heated for about 15 - 45 minutes at about 66 ~ 99 ° C (150 - 210 ^ö P) in the aqueous hydrogen peroxide solution and the concentration of the alkali hydroxide in the hydrogen peroxide solution is about 1.0 to about 1, 5 wt. ^ Is held 2. The method according to claim 1, characterized in that a about 0.7-1.5 wt .- ^ containing hydrogen peroxide Hydrogen peroxide solution is used. 3. The method according to claim 1, characterized in that that one containing about 1-3% by weight of sodium silicate Hydrogen peroxide solution is used. 9.0 9810/0723