US2161045A - Bleaching - Google Patents

Bleaching Download PDF

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Publication number
US2161045A
US2161045A US145806A US14580637A US2161045A US 2161045 A US2161045 A US 2161045A US 145806 A US145806 A US 145806A US 14580637 A US14580637 A US 14580637A US 2161045 A US2161045 A US 2161045A
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Prior art keywords
light
pulp
chlorine
millimicrons
cellulose
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Expired - Lifetime
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US145806A
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English (en)
Inventor
Hirschkind Wilhelm
David J Pye
Earl G Thompson
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Dow Chemical Co
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Dow Chemical Co
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Priority to US989185D priority Critical patent/UST989185I4/en
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Priority to US145806A priority patent/US2161045A/en
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/1015—Bleaching ; Apparatus therefor with use of means other than pressure, temperature
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06L—DRY-CLEANING, WASHING OR BLEACHING FIBRES, FILAMENTS, THREADS, YARNS, FABRICS, FEATHERS OR MADE-UP FIBROUS GOODS; BLEACHING LEATHER OR FURS
    • D06L4/00—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs
    • D06L4/50—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs by irradiation or ozonisation

Definitions

  • This invention relates to improvements in the use of oxidizing materials, particularly materials which are used to effect oxidizing bleaches.
  • oxidizing materials particularly materials which are used to effect oxidizing bleaches.
  • Such materials include chlorine,hypochlorous acid, the hypochlorites, water solutions of chlorine, hydrogen peroxide, peroxides, 'and per salts as perborates, persulphates, and permanganates.
  • the invention is broadly applicable to the bleaching of materials generally, but it will be described in connection with the bleaching of cellulose materials, particularly wood pulps such as sulphite, soda and kraft pulps. However, it is to be understood that this is only disclosed as a typical application of the invention which is also useful on other materials as well as pulps, for example, to the bleaching of cloths, rags, wool and other,
  • v '1 .Cellulose pulps are ordinarily bleached with chlorine water, hypochlorous acid, or hypochlorites.
  • the initial portion of the bleaching treatment whether the treatment be conducted in a single or a plurality of stages, if analyzed, will be found to be a chlorination step. That is, materials in the pulp are chlorinated by the available chlorine or by -the hypochlorite to form chlorinated addition and substitution products. Further treatment of the pulp is thereafter conducted to oxidize coloring material. Between the chlorination and oxidizing treatment, the pulp may or may not be washed to remove the soluble chlorinated materials with acid, alkaline or plain water washes.
  • Escourrou He reported (Congres de la Papeterie, June, 1928, and Chimie et4 Industrie, June, 1928) that while the ultra violet light sensibly diminished the time of bleaching, it resulted in a greater consumption of chlorine and, because the chlorine became more active, a cellulose attack occurred which lowered the yield. Further, Escourrou found that the .bleached cellulose was rich in oxy and hydroxy celluloses. the presence of which was revealed by an appreciable elevation in the copper'number. Escourrou reported an undesirable decrease in the alpha cellulose content and an increase in the formation of beta and gamma celluloses. These ndings led him vto advise against the use of light bleaching, particularly if.
  • the visible light present is not of any appreciable value'.
  • the eiective light band is that passed by a boro-silicate glass such as Crown glass or Pyrex. Apparently light rays shorter than about 300 millimicrons have a detrimental eifect upon cellulose, and hence the reason for Escourrous finding.
  • the specific preferred light for use on wood pulp is that having a wave length of 365 millimicrons.
  • Another object of the invention is to provide an improvement in bleaching wherein a selected light band is eiiectively used to improve the color without damage to the bleached material.
  • the invention includes other objects and fea ⁇ tures of advantage some of which, together with the foregoing, will-'appear hereinafter wherein the present preferred practice is disclosed.
  • a further object of the invention is to improve -the 4oxidizing ability, of oxidizing materials used for bleaching, as measured by color improvement.
  • Figure 1 illustrates the decomposition rate of various solutions when subject to light for the time indicated.
  • Figure 2 illustrates the chlorine consumption rate of a pulp treated with a 3% chlorine water with and without light.
  • FIG 3 illustrates the relative chlorine consumption'of the same pulp treated initially in the dark and thereafter divided and treated with and without light.
  • FIGs 4 ⁇ and 5 illustrate the chlorine consumption, the viscosity, copper number and percent of alpha cellulose in a pulp treated with and without light.
  • Figure 4 shows the first stage treatment and
  • Figure 5 shows the second stage treatment.
  • Figure 6 illustrates the same factors as in Figures 4 and 5 applied to the second stage, of another pulp.
  • Figures 7 and 8 indicate second stage chlorine consumption values onA a sulphite pulp.
  • Figure 9 illustrates diagrammatically the ab- 18% hydrochloric acid solution, and a solution of chlorine in water.
  • the results, as set forth in Figure 1, indicate that the light is much more effective on the hypochlorous acid than on the chlorine. It is to be noted that the sodium hypochlorite is relatively stable under the light. 'I'he conclusion drawn from this is that any improved results ⁇ are due to something other than an increase in the rate of decomposition of the hypochlorite.
  • the chlorination stage is indicated by a high percentage chlorine consumption in the rst five minutes at the particular chlorine concentration. Thereafter, in the presence of light, the chlorine consumption proceeds at a second very definite rate, while, in case light is absent, some few minutes elapse before the second rate of chlorine consumption is definitely established. There is an interval of secondary reaction which cannot be definitely explained but which is eliminated by the use of light, Aduring the chlorination operation. The value o f this secondary reaction will be discussed hereinafter in connection with Figure (i.
  • the irradiating light should be restricted to that selectively absorbed by the encrusting material, that light selectively absorbed by the other material, cellulose, for example, being substantially absent.
  • FIG. 3 is shown the chlorine consumption on a sulphite pulp in the first stage.
  • the sample was treated with 3% of chlorine for thirty minutes. This is equivalentto a chlorination operation. After this, the light was turned on and the increase in chlorine consumption is plainly indicated upon that portion of the sample which was subject to the light, as compared to that which Was permitted to remain me ely in the original condition.
  • the color of the pulp treated under the light was very much brighter than that run under normal conditions, that is without the use of the light during the last portion of the single stage treatment.
  • the second stage viscosity shown in Figure 6 shows a marked increase. This is followed by a decrease in viscosity directly correlated with the,
  • the invention is applicable to the materials generally. It can be used to advantage in any case wherein an oxidizing bleach is employed. Cellulosic materials as the aforementioned pulps are most advantageously treated. Some pieces of unbleached muslln were treated in a single stage CaOClz bleach using 6% available chlorine. One sample was radiated directly with ultra violet light from the quartz lamp, the secondwas radiated with light from the same u source but filtered through Pyrex glass and the third sample was treated without light as a control. The bleach was somewhat slower and the chlorine consumption in the unradiated sample was more constant than in pulp bleaching but the v general eiect of the light is identical with that on the wood pulp. The speeds-up the bleach and results in a higher color while the direct radiated bleach is ineilicient from a chlorine consumption standpoint. The brightness and chlorine consumption are shown below:
  • Sulflte pulp was treated in each case with a thirty minute first stage chlorine bleach at 4% consistency using 5% C12 on the weight of stock. The bleached pulp was then washed and the soluble chlorinated lignin extracted with a 0.2% NaOH wash. The second stage bleach was run at 2.5% consistency using 1.5% C12 as CaOClz.
  • the effective light band may be found to have other limits but the determination of these is a simple matter of determining the bands selectively absorbed by the ma terial to be oxidized and that to be unaffected. The irradiations are then restricted to that absorbed by the material to be oxidized so that it valone is activated. This is illustrated in' Figure 9 wherein the absorption characteristics of vthe coloring matter and of a bleached sulte pulp are shown. The lcoloring matter absorption is indicated by line A and that of the bleached pulp by line B. To activate the coloring matter selectively while avoiding thev degradation of the pulps one should restrict the irradiation so that little, if any, effective radiations below line C are included. Practically, the only effective radiations for the coloring matter which are not harmful to the cellulose are those included in the shaded area of Figure 9.
  • the light source utilized in some of the present work was a mercury vapor General Electric lamp designated as H-L
  • H-L This lamp has an inherent emission ycapacity for the 365 m. m. band, furnishing this radiation at comparatively high intensity.
  • the only shorter band emitted is the 334 band. 'I'he intensity of this emission is low and the band is readily elimil ated by a suitable lter.
  • the present invention enables bright pulps to be secured, activating the oxidizable coloring material, low temperature operation is made feasible and we have successfully bleached pulps at 20"25V C. and below. This means an increase in steam economy with even increased brightness. At high temperatures ⁇ the present invention enables the time of treatment -to be shortened, thus avoiding pulp degradation due to heat.
  • the process of the present invention is applicable. to oxidizing operations generally as performed on cellulose materials. It is particularly useful in producing high alpha cellulose pulps.
  • the step of improving a cellulosic material undergoing an oxidizing bleach which consists in irradiating the material with only those light waves longer than 300 millimicrons and below 420 millimicrons.
  • a process of improving the quality of a cellulose pulp which includes subjecting the pulp, 'in aqueous suspension, to the action of effective light all of a wavelength substantially longer than 300 millimicrons while said pulp is undergoing an oxidizing phase of a bleaching operation.
  • step in improving the quality of a cellulosic material which consists in irradiating said material with only those light waves longerthan 300 millimicrons and below 420 millimicrons while subjecting said material to an oxidizing bleach with a material selected from the group consisting of a peroxide, a perborate, a persulfate, a permanganate and hydrogen peroxide.

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  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Textile Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
US145806A 1937-06-01 1937-06-01 Bleaching Expired - Lifetime US2161045A (en)

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2668772A (en) * 1951-04-05 1954-02-09 Harry A Mulvany Bleaching process
US2850640A (en) * 1954-05-17 1958-09-02 Dow Chemical Co Chlorine analyzer
US2882211A (en) * 1953-10-12 1959-04-14 Evert A Autrey Method of mineral benefication
US3927967A (en) * 1972-06-02 1975-12-23 Procter & Gamble Photoactivated bleaching process and composition
US4294654A (en) * 1980-03-21 1981-10-13 International Paper Company Delignification and bleaching of lignocellulosic pulp via photo-oxygenation
US4390441A (en) * 1980-04-11 1983-06-28 Lever Brothers Company Machine dishwashing composition
WO1984000181A1 (en) * 1982-06-24 1984-01-19 Scott Paper Co Ozone bleaching of cellulosic materials
US4460373A (en) * 1980-04-11 1984-07-17 Lever Brothers Company Particulate detergent composition and method for cleaning fabrics
WO1992015744A1 (en) * 1991-03-05 1992-09-17 Lappage, James Photobleaching process for natural fibres
US5595572A (en) * 1993-02-16 1997-01-21 The Commonwealth Of Australia Commonwealth Scientific And Industrial Research Organization Wool and wool-blend fabric treatment
US20040129394A1 (en) * 2001-03-15 2004-07-08 Ian Graveson Pulp treatment and process
US20070246176A1 (en) * 2004-06-08 2007-10-25 Shoichi Miyawaki Pulp Bleaching Processes
US20090090478A1 (en) * 2007-10-05 2009-04-09 Hollomon Martha G Selectivity improvement in oxygen delignification and bleaching of lignocellulose pulp using singlet oxygen

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2668772A (en) * 1951-04-05 1954-02-09 Harry A Mulvany Bleaching process
US2882211A (en) * 1953-10-12 1959-04-14 Evert A Autrey Method of mineral benefication
US2850640A (en) * 1954-05-17 1958-09-02 Dow Chemical Co Chlorine analyzer
US3927967A (en) * 1972-06-02 1975-12-23 Procter & Gamble Photoactivated bleaching process and composition
US4294654A (en) * 1980-03-21 1981-10-13 International Paper Company Delignification and bleaching of lignocellulosic pulp via photo-oxygenation
US4460373A (en) * 1980-04-11 1984-07-17 Lever Brothers Company Particulate detergent composition and method for cleaning fabrics
US4390441A (en) * 1980-04-11 1983-06-28 Lever Brothers Company Machine dishwashing composition
WO1984000181A1 (en) * 1982-06-24 1984-01-19 Scott Paper Co Ozone bleaching of cellulosic materials
AU593763B2 (en) * 1982-06-24 1990-02-22 Scott Paper Company Ozone bleaching of pulp
WO1992015744A1 (en) * 1991-03-05 1992-09-17 Lappage, James Photobleaching process for natural fibres
US5595572A (en) * 1993-02-16 1997-01-21 The Commonwealth Of Australia Commonwealth Scientific And Industrial Research Organization Wool and wool-blend fabric treatment
US20040129394A1 (en) * 2001-03-15 2004-07-08 Ian Graveson Pulp treatment and process
US7267744B2 (en) * 2001-03-15 2007-09-11 Sappi Limited Pulp treatment and process
US20070246176A1 (en) * 2004-06-08 2007-10-25 Shoichi Miyawaki Pulp Bleaching Processes
US20090090478A1 (en) * 2007-10-05 2009-04-09 Hollomon Martha G Selectivity improvement in oxygen delignification and bleaching of lignocellulose pulp using singlet oxygen

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Publication number Publication date
UST989185I4 (enrdf_load_stackoverflow)

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