CH638003A5 - METHOD FOR PRODUCING MEDIUM TO highly viscous SOFTWOOD PULP. - Google Patents

Description

638 003

2nd

PATENT CLAIMS The sequence level corresponds, for example, to 0.01 to 20% by weight.

1. A process for producing a medium to highly viscous amount of chlorine, which in previously known chlorination softwood sulfite pulp, characterized in that stages are used. In the known processes, 4, not up to 6% by weight of chlorine obtained by a sulfite digestion process are used (cf. Rydholm, Pulping, Processes - or at most partially 5 ses by pretreatment, (1965) Interscience Publishers, Verlag Wiley & Sons, Inc. delignified pulp of an alkali refinement at New York, London, Sidney, page 1066). While subjecting to elevated temperature, then using peroxide in known processes, it is necessary to delignify the reaction time in the alkaline, aqueous medium and to extend one or chlorination step up to one hour. the inventive method, the reaction time of

2. The method according to claim 1, characterized in that the chlorination step is limited to a maximum of 0.80 h, preferably between that of the cellulose of a partially delignifying preliminary and 0.01 and 0.75 h.

action in the form of a partial chlorination and / or acid treatment. In a preferred embodiment of the invention, the action can be carried out. j chlorination can be carried out at a pH of 1 to 2

3. The method according to claim 1 or 2, characterized. This value can be determined using known inorganic minenets, which can be used in the delignifying treatment with peracrylic acids, e.g. HCl, H2SO4 can be set.

xid in alkaline, aqueous medium, magnesium salts. The acidic pretreatment can be done with inorganic mineral. acids such as H2S04, HCl, H2SO3 and / or organic acids, such as formic acid, acetic acid, at a pH of 2 to 5, at a temperature of 0 to 50 °, a consistency of 20 2 to 5 wt .-% and within one Duration of at least 1 The invention relates to a process for the preparation of a minute, preferably from 0.1 to 1 h, to be carried out on medium to highly viscous needle sulfite pulp, for example the refinement of the following after the cooking process is not wise for the chemical Further processing as well as for the manufacture or only slightly further delignified pulp with the provision of special papers is suitable. Alkali can at temperatures from 60 ° C to the boiling point

Medium to highly viscous pulp suspension refined by alkali treatment. A ter softwood sulfite pulp can be used as the base material for the duration of at least 0.1 h, preferably from 0.5 to 4 h, the provision of special papers, e.g. Photo papers, used. a consistency of at least 6 wt.%, preferably 10. A further possible application for refined softwood sul to 20 wt.%, and an alkali concentration of 2 to 12 microfiber is the use as a base material in the manufacture wt. (based on 100% dry cellulose), adhered to the development of cellulose esters, cellulose ethers, plastic masses 30 den.

and hygienic products, e.g. Baby diapers. When delignification with peroxide can be used as a peroxide

Inorganic peroxide, e.g. Hydrogen peroxide, sodium has been found to be a softwood sulfite pulp containing a peroxide, or an organic peroxide, e.g. t-Butylhydrope-high a-cellulose content of at least 91% by weight (based on roxide or a mixture of the peroxides mentioned, used on dry cellulose), a DP value of at least 1000, a 35. The peroxide used can be in amounts of 0.2 to good reactivity, a maximum extract content of 10% by weight, preferably 0.6 to 6% by weight, based on 0.2% by weight (dichloromethane) and an ash content of maxi-100% dry cellulose.

times 0.15 wt .-% (based on dry cellulose). Furthermore, a delignification with peroxide

It is known to produce such softwood sulphite pulps - consistency of at least 4% by weight, preferably 6 to 16%, by observing the delignification after the previous 40% by weight.

Boil completely with elemental chlorine (see. For the formation of the alkaline, aqueous medium in the

S.A. Rydholm, Pulping Processes [1965], Interscience Publis delignification with peroxide, alkali hydroxide such as hers, published by Wiley & Sons Inc., New York, London, Sidney, e.g. NaOH, KOH, NH3 (OH), Mg (OH) 2 and / or alkaline earth side 1066). hydroxide, e.g. Calcium hydroxide, in amounts of 0.5 to 4

However, this method has the disadvantage that 45% by weight, preferably 1 to 3% by weight, based on 100% of the chlorine-atro cellulose used in the delignification process, is used. The temperature can arise during the nin-containing wastewater, which, if at all, can only be worked up with delignification with peroxide between 35 ° C and the boiling point with very great effort. point of the pulp suspension.

The object of the present invention is to develop a process. In addition, stabilizers, such as ethylenediaminetetra-ren for the delignification of pulps of the above specification, 50 acetic acid, diethylenetriaminepentaacetic acids, nitrilotriacetic acid, which give more environmentally friendly waste water. acid and / or polycarboxylic acid, according to DE-OS

This object is achieved by the method defined in claim 1 19 04 940, DE-OS 19 04 941 and / or DE-OS 19 42 556. be used.

In the method according to the invention, the process according to the main advantage of the method according to the invention can

Pulp obtained with sulfite digestion with 0.01 to 20 55 rens is that waste water is obtained which, owing to its weight% of the chlorine used in classic bleaching processes, contains a small amount of chloride ions or organically bound amounts and / or be acid-treated. chlorine is not just a regenerative treatment

In a preferred embodiment of the invention, but also in a circulatory system again, one can be introduced into the delignification process in the delignifying treatment with peroxide, using magnesium salt in the alkaline, aqueous medium. Another advantage is that the use of the magnesium salt in amounts of 0.01 to 1 in the pulp as a stabilizer can be used

% By weight, based on pulp, are used. can be dispensed with during delignification.

Magnesium salts which can be used in this way can contain magnesium salts.

halides, e.g. MgCk, MgBn or MgJ2, magnesium - the examples explained and described in more detail:

be carbonate, magnesium silicate, magnesium sulfate, magnesium acetate or magnesium oxide. example 1

If necessary in the process described in (production of a highly viscous pulp)

a pre-treatment amount of chlorine used in the first one produced by the calcium bisulfite process

3rd

638 003

Spruce sulfite pulp (kappa number = 17) is treated in a five-step process according to the following sequence:

1. weak chlorination (partial chlorination)

1% chlorine on pulp

Temperature 35 ° C Duration: 0.75 h Fabric density: 4%

pH value: approx. 2

2nd alkaline refinement 8% NaOH temperature: 85 ° C duration: 2 h fabric density 16%

3. Peroxide delignification

1.5% H2O2 (in aqueous solution)

Temperature: 40 ° C

2% NaOH

Duration: 4 h

Fabric density: 12%

0.3% MgCh on pulp

The pulp treated in this way has the following properties:

a-cellulose: 93%

Cuoxam viscosity: 2600 mp white content: 70% MgO (Elrepho)

Extract content: 0.06% (dichloromethane)

This pulp obtained after the delignifying pre-bleaching is then further treated in a manner known per se as follows:

4. Chlorine dioxide bleaching according to Ullmann's Encyclopedia of Industrial Chemistry, 18th volume, 3rd edition, page 780 (1967)

5. Hypochlorite bleaching according to Ullmann's Encyclopedia of Industrial Chemistry, 18th volume, 3rd edition, page 779 (1967)

The pulp thus obtained after the 5th stage has the following characteristics:

a-cellulose: 92%

Wood rubber: 2.9%

DP value: 1500

R 18: 93.6%

Ash content: 0.11%

Extract content: 0.04 (dichloromethane)

Copper number: 0.8

Whiteness: 91% MgO

Cuoxam viscosity: 2300 mp

The characteristic data are determined according to the following known methods:

a-Cellulose: Merkblatt Zellcheming IV / 39/67

or: Siber, chemical-technical investigation methods of

Pulp and paper industry Springer Verlag 1957, page 598

3. Delignification with peroxide 1.5% H2O2 (in aqueous solution)

Temperature: 40 ° C 1.5% NaOH

Duration: 4 h fabric density: 12%

0.3% MgCh

5 The fabric treated in this way has the following properties:

a-cellulose: 92.5%

Cuoxam viscosity: 1900 Whiteness: 70% MgO (Elrepho)

10 extract content: 0.05% (dichloromethane)

This pulp obtained after the delignifying pre-bleaching is then further treated in a manner known per se as follows:

15

4. Chlorine dioxide bleaching according to Ullmann's Encyclopedia of Industrial Chemistry, 18th volume, 3rd edition, page 780 (1967)

20 5. Hypochlorite bleaching according to Ullmann's Encyclopedia of Industrial Chemistry, 18th volume, 3rd edition, page 779 (1967)

The pulp thus obtained after the 5th stage has the following characteristics:

Wood rubber: leaflet Zellcheming IV / 9/67 DP value: leaflet Zellcheming DIII / 1/72 R 18: leaflet Zellcheming IV / 39/67 ash content: leaflet Zellcheming IV / 40/67 30 extract content: leaflet Zellcheming IV / 43/67 copper number : Merkblatt Zellcheming IV / 8/70 degree of whiteness: Merkblatt Zellcheming V / 10/63 Cuoxam viscosity: Merkblatt Zellcheming IV / 30/62

35 The concentration percentages given in this example are percentages by weight, based on 100% dry cellulose, unless another reference value is given.

Example 2

40 (production of a medium-viscosity pulp)

A spruce sulfite pulp (kappa number = 15) produced by the calcium bisulfite process is treated in a five-step process according to the following sequence:

<5 1. weak chlorination (partial chlorination)

0.8% chlorine gas (in aqueous solution)

Temperature: 45 ° C Duration: 0.75 h Fabric density: 4%

50 pH value: approx. 2nd

2. Alkaline finishing 6% NaOH (in aqueous solution)

Temperature: 85 ° C 55 Duration: 2 h Fabric density: 16%

a-cellulose: 93%

DP value: 1200 Ash content: 0.08%

60 extract content: 0.1-0.2% (dichloromethane)

Whiteness: 94% MgO Cuoxam viscosity: 600 mp

The characteristic data are determined according to the known methods given in Example 1 65.

The concentration percentages given in this example are percentages by weight, based on 100% dry cellulose, unless another reference value is given.