Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
  • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
  • D21H17/68—Water-insoluble compounds, e.g. fillers, pigments siliceous, e.g. clays
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
  • D06M11/32—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond
  • D06M11/36—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond with oxides, hydroxides or mixed oxides; with salts derived from anions with an amphoteric element-oxygen bond
  • D06M11/45—Oxides or hydroxides of elements of Groups 3 or 13 of the Periodic Table; Aluminates
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
  • D06M11/77—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with silicon or compounds thereof
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/01—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with natural macromolecular compounds or derivatives thereof
  • D06M15/03—Polysaccharides or derivatives thereof

Definitions

• the present invention relates to aqueous dispersions of particulate hydrophobic zeolites and to the use of said dispersion as an aid for binding hydrophobic zeolites to surfaces of natural as well as synthetic fibres in wet as well as dry state Furthermore the present invention relates to wet as well as dry methods for production of fibrous materials such as paper, paperboard, nonwoven, flake-dned pulp and suchlike, wherein said disper ⁇ sion is used in order to increase the retention of an added hydrophobic zeolite
• retention means the relation between the amount of a certain additive retained by the fibres and the total amount of said additive added to said fibres within a process step
• Storage stable aqueous zeolite dispersions are descnbed in Japanese Laid-Open
• a hydrophobic zeolite in this context, meant a zeolite having a hydrophobicity of below about 0 9 percent by weight residual butanol as determined by the Residual Butanol Test
• aqueous dispersion having the features set out in the characterising clause of appended claim 1 , i e the dispersion comprises a stabilising amount of a biogum
• Zeolites are inorganic crystalline compounds mainly comp ⁇ sing S ⁇ O 2 and AI 2 O 3 in tetrahedral coordination
• the term "zeolites” also bears upon other crystalline compounds of zeolite structure, such as aluminium phos ⁇ phates
• Such crystalline compounds of zeolite structure that can be used in the invention are defined in W M Meier et al, "Atlas of zeolite structure types", 2nd ed , Butterworths, London, 1987, hereby incorporated by reference in the present application
• the zeolites have a restricted capacity for taking up water
• Such a hydrophobic (water-repellent) nature also involves an increased capacity for associating with non-polar compounds, among which the organic substances constitute the largest group
• the present dispersion may contain more than one type of zeolite, for instance two hydrophobic zeolites, or a combination of one or more hydrophilic zeolites with one or more hydrophobic zeolites
• the molar ratio of S ⁇ O 2 to AI 2 O 3 in tetrahedral coordination should be at least about 10 1
• the molar ratio lies in a range of from 12 1 to 1000 1 , preferably in a range of from 20 1 to 500 1
• the hydrophobicity of zeolites may be determined by a so-called Residual Butanol Test, described in GB-A-2,014,970
• the zeolite is activated by heating in air for 16 hours at 300°C
• 10 parts by weight of the thus-activated zeolite are mixed with a solution consisting of 1 part by weight of l-butanol and 100 parts by weight of water
• the resulting slurry is slowly agitated for 16 hours at 25 ⁇ C
• the residual content of l-butanol in the solution is determined and indicated in per cent by weight
• a low value indicates a high degree of hydrophobicity
• the hydrophobicity is suitably distinguished by a residual butanol content below about 09% by weight, preferably below about 06% by weight
• the residual butanol content lies suitably in a range of from about 0.0001% by weight to about
• the residual butanol content lies in a range of from about 0 0002% by weight to about 0 3% by weight
• Zeolites having a high degree of hydrophobicity are zeolites of pentasil type, faujasite type, mordenite, e ⁇ onite and zeolite L US-A- 3,702,886 and US-A-4,061 ,724, hereby inco ⁇ orated by reference, describe how to produce zeolites of pentasil type
• zeolites of the pentasil type are ZSM-5, ZSM-11, ZSM-8, ZETA-1 , ZETA-3, NU-4, NU-5, ZBM-10, TRS, MB-28, Ultrazet,
• the zeolite of pentasil type is conveniently ZSM-5 or ZSM-11 , preferably ZSM-5, both defined by P A Jacobs et al in "Synthesis of high-silica aluminosihcate zeolites, Studies in surface science and catalysis", Vol 33, Elsevier, 1987, pp 167-176, hereby inco ⁇ orated by reference
• Specific examples of faujasite type zeolites are Linde X, Linde Y, SAPO-37, CSZ-37, and LZ-210, all dis ⁇ closed in "Atlas of zeolite structure types" referred to above
• biogums that can be used in the present dispersion are such biogums mentioned in US-A-5,234,493, which document relates to suspensions of silica particles, not zeolite particles, and which suspensions require, in contrast to the present dispersions, surfactants to be stable
• the indicated biogums are obtainable by fermentation of a carbohydrate by bacteria or fungi of the genus Xanthomonas, Arthro- bachter, Azotobacter, Agrobacter, Alcaligenes, Erwinia, Rhizobium, Corticum
• a preferred biogum is a gum obtainable by fermentation of the bacteria of the genus Xanthomonas, i.e. xanthan gum.
• the electric conductivity of the present dispersion is at least about 3 mS/cm. Below this conductivity value the stability of the dispersions decreases rapidly, eventually resulting in hard sediments.
• the conductivity is preferably below about 20 mS/cm in order to keep the salt content in the fibrous products low.
• a preferred conduc ⁇ tivity range for the present dispersion is from about 4 to about 15 mS/cm, preferably from about 4 to about 8 mS/cm.
• the conductivity of the dispersion may be controlled by any suitable means, for instance by addition of a suitable amount of an electrolytically active substance such as an alkali metal salt, e.g. sodium sulphate, aluminium sulphate, or sodium chloride, or an acid, preferably an inorganic acid such as sulphuric acid, hydro ⁇ chloric acid, or nitric acid
• the pH of the aqueous dispersion of the present invention is preferably about 2-7, particularly about 3-5, in order to optimise the stability of the dispersion.
• the size of the hydrophobic zeolite particles may have some impact on the stability of the present dispersion.
• the particle size is preferably smaller than about 15 ⁇ m, i.e. about 50 percent by volume of the hydrophobic zeolite should preferably have a particle size of less than about 15 ⁇ m.
• hydrophobic zeolite dispersion It is often desirable to have the dry solids content of the hydrophobic zeolite dispersion as high as possible.
• the present invention makes it possible to obtain hydro ⁇ phobic zeolite dispersions having dry solids contents of about 30-50% by weight using as little as about 0.1-0.8% by weight of biogum, based on the weight of the hydrophobic zeolite particles; these dispersions have shown to have quite manageable viscosities, which is often conditional for their use.
• the present dispersion may advantageously be used in the production of packaging material such as described in EP-B-0 540 075 or for sizing of paper as dis ⁇ closed in US-A-5,374,335, especially for reduction of dust problems and for lowering the costs of energy and labour.
• the present dispersion also relates to a method for production of paper or paperboard by forming and dewate ⁇ ng a suspension of cellulosic fibres, and optional fillers, in which the dewatering is carried out in the presence of particles of a hydrophobic zeolite and the present dispersion is added to the suspension prior to dewatering
• the present dispersion has shown to give very good retention results regarding fluff and fluff pulp, in that the overall retention, i e the retained amount of hydrophobic zeolite in the fluff after dry-shredding of the fluff pulp, is increased by the present dispersion Tests have shown that the hydrophobic zeolite retention
• the present hydrophobic zeolite dispersion may also be used for application of hydrophobic zeolite on the surfaces of fibres, natural as well as synthetic, when added to the fibres while they are in a dry state
• the present invention particularly relates to a method for production of dry-laid paper, nonwoven or fluff pulp, in which the present dispersion is sprayed onto the fibres while the latter are in an essentially dry state, and particularly when they are carried by a flow of gas such as for instance air, nitrogen, or carbon dioxide
• the present dispersion may be applied on various synthetic fibres made of e g nylon, polyacetates, viscose, polyaramide etc
• the present hydrophobic zeolite dispersion may be prepared by the following method:
• the dry mixture is mixed with water, while being agitated, into a homogeneous mixture
• Adjuvants such as for instance bactericides may also be added to the dispersion. Mixing the hydrophobic zeolite particles with the biogum while dry has shown to provide for the best stability of the resulting dispersion.
• Another method for preparation of the present dispersion comprises the steps of
• Example 1 The hydrophobic zeolite used was of the ZSM-5 type, having a molar ratio of SIO 2 to Al 2 0 3 in tetrahedral coordination of 32, and a hydrophobicity of below about 0.9 percent by weight residual butanol as determined by the Residual Butanol Test.
• the pulverulent hydrophobic zeolite showed a pH of 3,7 when in an aqueous slurry.
• the dry solids content of the hydrophobic zeolite was about 96% by weight and the average size of the hydrophobic zeolite particles was about 10 ⁇ m.
• 208 g pulverulent hydrophobic zeolite was mixed with 0.8 g dry xanthan gum.
• the dry mixture was carefully poured into about 290 g water and was subjected to forceful stirring. After stirring for 10 minutes pH was measured to be 3.6 and the conductivity, which was measured according to standard method SIS 028123, was 0.33 mS/cm. 2.5 g water-free Na 2 S0 4 was added under stirring, upon which the mixture was stirred for 5 additional minutes. The conductivity then showed to be 5.5 mS/cm. After filtration the dispersion was poured onto a plastic bottle, which was agitated by a shaking apparatus for 3 days. The resulting dispersion, which was easy to stir, did not show any transparent phase and there was no sediment found in the plastic bottle. The conductivity was measured to 4.36 mS/cm and the pH to 3.6.
• Example 2 Example 1 was repeated, except that no Na 2 S0 4 was added. After 3 days a transparent liquid phase of 12 mm appeared, and the rest of the sample was hard as stone. The conductivity was measured to 0.23 mS/cm and the pH to 4.0. This Example indicates that the electric conductivity of the dispersion may be an important feature in
• Example 3 Example 1 was repeated, except that pH was adjusted with sulphuric acid to 2.5 and that no Na 2 SO 4 was added. After 3 days the entire dispersion sample was hard as stone. The conductivity was measured to 1.378 mS/cm and the pH to 2.7. This Example too indicates that the electric conductivity of the dispersion may be an important o feature in some embodiments of the present invention.
• Example 4 A pulverulent hydrophobic zeolite of the same kind as used in Example 1 and showing a pH of 10.0, when in an aqueous slurry, was used.
• the dry solids content of the hydrophobic zeolite was about 96% by weight and the average size of the hydrophobic zeolite particles was about 8 ⁇ m.
• 208 g pulverulent hydrophobic zeolite was 5 mixed with 0.8 g dry xanthan gum. The dry mixture was carefully poured into about 290 g water and was subjected to forceful stirring. After stirring for 10 minutes the conductivity was 0.33 mS/cm. Sulphuric acid was added to adjust pH to 3.0, upon which the mixture was stirred for 5 additional minutes.
• the conductivity then showed to be 5.5 mS/cm.
• the dispersion was agitated as in Example 1 for 3 days.
• the resulting dispersion 0 did not show any phase separation and the dispersion was easy to stir.
• the conductivity was measured to 5.02 mS/cm and the pH to 3.0. Two weeks later the dispersion, which was according to the present invention, was stilt easy to stir and no phase separation appeared.
• Example 5 Example 4 was repeated, except that only half the portion of sulphuric 5 acid was added and that Na 2 SO was added until about the same conductivity as in
• Example 4 was reached. After 3 days no phase separation could be detected and the dispersion was easy to stir. The conductivity was measured to 5.48 mS/cm and the pH to 7.4. Two weeks later the dispersion, also according to the present invention, was still easy to stir and no phase separation could be detected. 0
• Example 6 Example 1 was repeated, except that ethylhydroxyethyl cellulose was used instead of xanthan gum. A portion of the sample was not agitated; this portion showed a transparent phase and a small amount of sediment, which was easy to slurry by stirring. Agitation, however, made the sample very hard. The conductivity was measured to 6.85 mS/cm and pH to 3.7.
• Example 7 Example 1 was repeated, except that ethylhydroxyethyl cellulose was substituted for half the used amount of xanthan gum. A portion of the sample was not agitated; this portion showed good stability. Agitation, however, produced a sediment that was difficult to slurry by stirring. The conductivity was measured to 6.85 mS/cm and pH to 3.7. This Example indicates that the present invention may be used to improve prior art dispersions.
• Examples 8 Aqueous dispersions of hydrophobic zeolite of the same kind as in Example 1 were prepared using Dispex N-40, which is an anionic polyacrylate dispersing agent, in concentrations of 0.2, 0.5 and 1 wt-%, based on dry hydrophobic zeolite. The dry contents of the dispersions varied from 20% to 40% and the pH of the dispersions were 4.5, 7 and 9, respectively. Irrespective of mixing conditions sedimentation appeared very quickly in the dispersions. After one day the hydrophobic zeolite material had settled at the bottom as a very hard cake. This Example shows that prior art technology does not provide stable dispersions of hydrophobic zeolites.
• Example 9 Example 1 was repeated, except that 21 g Na 2 SO 4 was added
• Example 10 Table I below shows the results of retention tests in which a hydro ⁇ phobic zeolite as used in Example 1 and xanthan gum were added to fibrous suspensions containing fibres from a Kraft pulp of 60% hardwood and 40% softwood. The pulp concen ⁇ tration was 1% by weight. The hydrophobic zeolite was added in an amount of 10 kg/ton of dry pulp.
• the suspension was dewatered and the fibres were formed into a sheet, which was dried at 105°C.
• the degree of retention of the hydrophobic zeolite was measured by means of the ash content, which was determined by combustion at 925°C for 120 min, upon which the remainder was weighed.
• the hydrophobic zeolite was added to the fibrous suspension separate from the xanthan gum, whereas in test Nos. 2 and 4 the hydrophobic zeolite was mixed with the xanthan gum prior to being added to the fibrous suspension.
• Table I the additions of hydrophobic zeolite and xanthan gum are calculated per ton of dry pulp. Table 1
• Example 11 In test A, an aqueous dispersion of a hydrophobic zeolite was prepared and added, while stirring at 1000 rpm, to a fibrous suspension as described in Example 10. The added amount of hydrophobic zeolite was 10 kg/ton of dry pulp. The suspension was dewatered and the fibres were formed into a sheet, which was dried at 105°C. The ash content of the sheet after forming was determined as in Example 10. Thereafter the sheet was dry-shredded into fluff, upon which the ash content of the obtained fluff was determined. In test B the aqueous hydrophobic zeolite dispersion additionally contained xanthan gum in an amount of 40 g/ton of dry pulp, i.e. the dispersion was according to the present invention. The results of the tests are set forth in Table Ii below. The ash contents have been converted into the amount of hydrophobic zeolite present in the pulp sheet and in the fluff, respectively.
• Example 12 An aqueous solution containing 2 g/l of a hydrophobic zeolite as used in Example 1 were sprayed onto sheets of pulp, the sheets being prepared as described in Example 10. The added amount of hydrophobic zeolite corresponded to 3 kg hydrophobic zeolite/ton of dry pulp. In Test C, the solution additionally contained 0.04% of xanthan gum, whereas Test D was a comparison test without any biogum added. After having being sprayed, the pulp sheets were shredded in a hammer mill, and the ash contents were determined as in the previous Examples and converted into the corresponding amount of hydrophobic zeolite present in the shredded pulp. The results of the Tests are set forth in Table III below.
• Example 13 The hydrophobic zeolite used in this Example was of the Y type, having a SiO 2 :AI 2 0 3 ratio of 29, and a hydrophobicity of 0.28 percent by weight residual butanol as determined by the Residual Butanol Test.
• the pulverulent hydrophobic zeolite showed a pH of 3,7 when in an aqueous slurry.
• the dry solids content of the hydropho ⁇ bic zeolite was about 96% by weight.
• 208 g pulverulent hydrophobic zeolite was mixed with 0.8 g dry xanthan gum.
• Example 2 The dry mixture was poured into about 290 g water and was stirred as in Example 1 for 10 minutes, after which the pH was measured to be 3.6 and the conductivity was 0.33 mS/cm. 2.5 g Na 2 S0 4 was added as in Example 1 , and then the conductivity showed to be 5.6 mS/cm. After filtration the dispersion was poured onto a plastic bottle, which was agitated for 3 days. The resulting dispersion was easy to stir, did not show any transparent phase and there was no sediment found in the plastic bottle. One and a half weeks later the dispersion was still easy to stir and no sediment was present.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Dispersion Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Paper (AREA)
• Colloid Chemistry (AREA)
• Silicates, Zeolites, And Molecular Sieves (AREA)

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