SE436768B - Procedure for manufacturing fluff pulp - Google Patents

Abstract

Fluff substance that can be dry defibrated with low energy consumption to fluff with high absorption ability is produced through1. addition before or on the pulp machine wire of ampholytic surfactants and/or surfactants that at a low pH are cationic and at a high pH are non-ionic, whereby the pH is held so low that the surfactants are accessible in cationic form, and thereafter2. increase of pH so much that the surfactants are transferred to their anionic respectively non-ionic forms, which pH-increase occurs exactly before the pulp course leaves the pulp machine wire or before one of the presses or between the last press and drying section or in the drying section or simultaneously as the substance is feed into the fluffing machine.

Description

asozzsa-o iQ straight or branched aliphatic alcohols having at least 8 carbon atoms in the alkyl chain carbonic acid amides having at least 12 carbon atoms in the alkyl chain and ethanol amides with straight or branched aliphatic hydrocarbons having at least 12 carbon atoms in the hydrocarbon chain, to the pulp before or on the pick-up machine in an acidic environment, ie at pH values below 7.

By raising the pH of the pulp, the additives are transferred from them cationic form to their anionic and nonionic forms, respectively on the nature of the additives). This increases the liquid absorption of the final product. ability.

This pH increase must be done so that the intended effect of the additives on the defibrillability of the mass is not lost and must therefore take place after that the water content of the pulp has been significantly reduced.

According to the invention, the following alternatives are provided for carrying out the pH increase: An alkaline liquid is added to the pulp web a. just before it leaves the wire b. immediately before one or more of the presses c. between the last press and the drying section d. in the drying section, whereby the supply is made so fast that the web becomes soaked before the liquid has time to evaporate to any significant extent e. in connection with the feeding of the pulp into the fluffing machine ( ring machine) By changing the nature of the surfactant in this way, after it has filled its task of preventing the formation of fiber bonds, one counteracts its 'tendency to hydrophobize the fibers. Their fluid absorption capacity is increased thereby. For further reinforcement of this effect can - if necessary a surfactant mixture is added to the pulp before or on the pick-up machine, containing an ampholytic and / or cationic / nonionic surfactant to facilitate defibration and a non-cationic surfactant to increase liquid absorption sorption capacity m m, eg a nonionic or anionic surfactant. 630325li-0 3 A. Examples of ampholyte-type surfactants which act cationically in acidic and anionic in alkaline environment may be mentioned: a) eminocarboxylic acids or aminosulfonic acids of the general formula R M / z \ in Ra wherein R1 represents a straight or branched, saturated or unsaturated alkyl radical having 8-24 C atoms, R 2 denotes H, a short alkyl radical having 1-6 C atoms or a chain containing 1-40 oxyethylene groups, and R 3 is a residue containing a -COOH or a -SO 3 H group.

As an example may be mentioned (C2H4 °) 20H + ° 1e “37'ï c2H4oc2H4coo Furthermore, betaines should be mentioned here. These are internal ammonium salts. and may contain one or more amino groups. As example beta are mentioned by the general formula X 3 R1-nu-Ä-R2-ï + -R5-coo ' R4 wherein R1 represents a straight or branched, saturated or unsaturated alkyl radical having 8-24 C atoms, R 2 and R 5 represent alkylene groups with 1-2 C atoms, Ra is a -CnH2n + 1- or -CnHZnOH group where n is equal to an integer between 1 and 10, or one - (C2H4O) xH group with x equal to an integer between 2 and 100, R; may be Ra or an R1-NH-C-RT, -RS-COO1-k- or -RS-COOMe group, wherein R 1, R 2, R a and R 5 are defined as before, Me is a monovalent, salt-forming radical and X means O or S. Among betaines are stearyl betaine, soy ammonium sulpho- betaine, palnitylammonium carboxylbetaine and talgamidoammo- niumsulfobetain are mentioned, which are commercial products. 8303254-0 b) imidazoline derivatives The preparation of these products is based on the imidazoline compounds of the general formula N -'---- CH I 2 / \ in 1l \ I ---- CH2 CH ZCH 2OH which are carboxymethylated during the introduction of one or more CH2COO ~ groups or sulfonated or sulphated. R means one straight or branched, saturated or unsaturated alk atoms. yl group with 8-24 C- An example is a commercial product, Mira which in anhydrous acid- zero CZM is mentioned, for form, the following formula is given NT Lv CHZ CHZOCHZCOOH B.

As an example of tensile age which acts cationically in acidic and nonionic in alkaline or neutral environment may be mentioned alkylene oxide derivatives of (a) monoamines comprising: 1. N-primary alkylamines with 1D- 22 C atoms in a straight line or branched, saturated or unsaturated alkyl residue, eg tallow fatty amine or stearylamine 2. tert-alkyl primary amines, * cla-zzNHz for example t-Cl2_l4NH2 or 3. resin amine eg dehydruabietylamine (b) polyamines comprising _ ___._._-_ ___.._._._._._.__._.______ 8303254 'Û N-alkyl-alkylenediamines having 12-24 C atoms in the alkyl group which may be straight or branched, saturated or unsaturated and 1-12 C atoms in the alkylene group, for example tallow fatty amine-propylenediamine and Alkylpolyalkylene polyamines of the general formula R-N1-1- (βnHzn-Nmx-CnHzn-NH2, wherein R group which may be straight or branched, saturated or unsaturated and contains 12-24 C atoms, n is an integer between 1 and 12 and x are an integer between 1 and 8.

Alkylene oxide derivatives of said amines are obtained by storage of ethylene oxide or of ethylene oxide and a higher alkylene oxide containing 3-6 C- atoms, wherein the higher alkylene oxide can be deposited before, together with or after the ethylene oxide.

Example 1 Experiment with an ampholytic binding inhibitor consisting of one complex talgammonium carboxylate.

The binding inhibitor was added to a 2.5% slurry of sulfate pulp fibers. at pH 4.5. After stirring for 10 minutes the suspension was diluted 0.5% fiber concentration and formed into sheets (dry basis weight 750 g / mz) in a laboratory sheet form.

Some of these test sheets (sample B) were pressed without pH change to 40% dry content. The other sheets (sample C) were pressed to 3D% dryness, then pH i the sheets were raised to 10.5 by showering with, calculated on 1 g of dry-mass, 10 g of alkaline water with the sheets placed on a suction filter that pulled of the excess water. These sheets were then pressed to a 40% dry content.

For comparison, sheets (sample A) were made of sulphate pulp that was not added binding inhibitors.

All test sheets were dried to 93% dry content after pressing as well was conditioned at 23 ° C and 50% relative humidity. Then they were torn down fluff in a stud roller. The energy consumed during demolition, demolition energy, was read. 8303254-0 Fluff pads with a diameter of 50 mm and a weight of 2 g were formed. They were pressured to a height of 15 mm which was kept constant. The time it took for water to be sucked up from the bottom surface of the pillow to its top surface, the absorption time, was measured.

The test results are shown in Table 1.

Table l Sample Dosage of binder pH pH Tear Absorption inhibitor, active at the energy time amount of substance per sheet form- final the amount of fiber pressed ningen % kJ / kg s A 0 7 4.5 4.5 440 2.5 B 0.6 4.5 4.5 330 3.8 C 0.6 4.5 10.5 535 2.8 The effect of the binding inhibitor is shown in the fact that the tear energy has dropped 400 kJ / 'kg (sample A) to about 330 kJ / kg (sample B) and the effect of the pH increase in that the absorption time has dropped from 3.8 s (sample B) to 2.8 s (sample C), ie to approximately the same value as for the untreated pulp (sample A).

Example 2 Experiment with a binding inhibitor, which changes with increasing pH from being cationic to being nonionic, consisting of ethoxylated tallow fatty amine with two oxyethylene groups.

The binding inhibitor was added to a 2.5% slurry of sulfate pulp. fibers at pH 5.5. After stirring for 10 minutes the suspension was diluted to 0.5% fiber concentration and formed into sheets (dry solid basis weight 750 Qlmz).

A portion of the sheets (sample D) was pressed without pH change to 40% dry matter.

The other sheets (sample E) were pressed to 30% dry matter and the pH of the sheets was raised to 1.0 by showering with, calculated on 1 g of dry-mass, 10 g of alkaline water in which the sheets were placed on a suction filter which pulled off excess the water. These sheets were then pressed to a 40% dry content. 830325li-0 A third fluff pulp sample (Sample F) was prepared by adding binder inhibitor at pH 11.0 to a 2.5% slurry of sulphate pulp. fibers and stirring for 10 minutes of this, diluting and forming sheets (dry solid basis weight 750 g / mz) and pressing to 4D% dry matter without pH change.

All test sheets were dried to 93% dry content after pressing as well was conditioned at 23 ° C and 50% relative humidity.

Fluff was prepared from the pulps and tested as in Example 1. Experimental results are given in Table 2.

Experiments D and F show that the pH must be set in the 2.5% fiber the slurry in order for the binding inhibitory effect to be phased, ie the substance must be in its cationic form.

Table 2 Sample Dosage of binder pH pH Tear Absorption ningshëimmare, active at the energy -tion time amount of substance per sheet form- final the amount of fiber pressed ningen % kJ / kg I s D 0.35 5.5 5.5 285 10.5 E 0.35 5.5 11.0 296 7.4 F 0.35 11.0 11.0 423 4.1 Experiment E shows that pH increase can be done in pressed mass without it In binding inhibitory effect is lost. At the same time, the absorption time is reduced considerably. 1 Example gel 3 Try a mixture of a binding inhibitor and a wetting agent, the binding inhibitor being ethoxylated tallow fatty amine containing two oxyethylene groups and has the property of at pH increase transition from cationic to nonionic state and whereby the wetting agent is nonionic and consists of a Clz-CM alcohol adduct. , 830325ls-Û To a 2.5 'Vu-ig slurry of sulphate pulp fibers was added at pH 5.5 parts the binding inhibitor and the wetting agent. After stirring for 10 minutes off suspension, it was diluted to 0.5% fiber concentration and formed sheet (dry-think: ycvm; 750 g / mz).

A portion of the sheets (sample G) was pressed to 40% dry matter without changing the pH.

The other sheets (sample H) were pressed to 30% and the pH of the sheets was raised 11.0 by showering with, calculated on 1 g dry-dried mass, 10 g alkaline water in which the sheets were placed on a suction filter which pulled off excess the water. These sheets were then pressed to a 40% dry content.

All test sheets were dried to 93% dry content after pressing as well was conditioned at 23 ° C and 50% relative humidity.

Fluff was prepared from the pulps and tested as in Example 1. The results are shown in Table 3. For comparison, Experiment D from Example 2, Table 2 has been introduced.

Table 3 Sample Dosage of binder pH pH Tear Absorption inhibitor, active at the energy time amount of substance per sheet form- final the amount of fiber pressed ningen binding wetting agent inhibitors %% kJ / kg s D 0.35 0.0 5.5 5.5 285 10.5 G 0.35 0.5 5.5 5.5 253 5.2 H 0.35 0.5 5.5 11.0 272 4.1 Comparison between experiments D and G shows the positive effect on absorption time of the wetting agent.

Experiment H shows that the pH increase significantly reduces the absorption time without severe increase in demolition energy.

Claims (9)

8303254-0 Patent claims Process for the production of highly absorbent cellulosic pulp, characterized in that the pulp before or on the pick-up machine is facilitated by 0,01 - 2%, calculated on the dry weight of the pulp, by an additive containing at least one errfolytic and / or or at least one - depending on the pH value - cationic or nonionic surfactant and that the pH of the pulp when the surfactants are added is kept so that the surfactants are in their cationic forms and that the pulp is additionally added to one or more absorption-promoting substances and that the any moment in the fluff production is raised so much that the surfactants are transferred to their anionic and nonionic forms, respectively. Process according to Claim 1, characterized in that the absorption-promoting additive consists of at least one anionic surfactant. 3. A method according to claim 1, characterized in that the absorption-promoting additive consists of at least one nonionic surfactant. 4. A method according to claim 1, characterized in that the absorption-promoting additive consists of at least one straight or branched chain fatty alcohol containing at least 8 carbon atoms. 5. A method according to claims 1-4, characterized in that the pH of the pulp just before the pulp web leaves the wire is raised so much that the surfactants turn into anionic and nonionic form, respectively. 6. A method according to claims 1 - 4, characterized in that the pH of the pulp is raised immediately before any of the presses so much that the surfactants turn into anionic and nonionic form, respectively. 7. A method according to claims 1 - 4, characterized in that the pH of the pulp, when the pulp web is between the last press and the drying section, is raised so much that the surfactants turn into anionic and nonionic form, respectively. A method according to claims 1 - 4, characterized in that the pH of the pulp is raised in the drying section so much that the surfactants turn into anionic and nonionic form, respectively. 830325lr-0 10 9. A method according to claims 1-4, characterized in that the pH of the pulp in connection with the feeding of the pulp into the fluff machine is raised so much that the surfactants turn into anionic and nonionic form, respectively.