GB2297334A - Agent for controlling the deposition of pitch in papermaking - Google Patents
Agent for controlling the deposition of pitch in papermaking Download PDFInfo
- Publication number
- GB2297334A GB2297334A GB9501406A GB9501406A GB2297334A GB 2297334 A GB2297334 A GB 2297334A GB 9501406 A GB9501406 A GB 9501406A GB 9501406 A GB9501406 A GB 9501406A GB 2297334 A GB2297334 A GB 2297334A
- Authority
- GB
- United Kingdom
- Prior art keywords
- control agent
- exchangeable cations
- pitch control
- type
- smectite clay
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
- C01B33/38—Layered base-exchange silicates, e.g. clays, micas or alkali metal silicates of kenyaite or magadiite type
- C01B33/40—Clays
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/40—Compounds of aluminium
- C09C1/42—Clays
-
- 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
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/02—Agents for preventing deposition on the paper mill equipment, e.g. pitch or slime control
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
Description
ANT FOR CONTROLLING THE DEPOSITION OF PITCH IN PAPERMARING This invention relates to an agent suitable for incorporation in cellulose pulp compositions to reduce the adverse effects of the deposition of pitch derived from wood pulp in the manufacture of paper and board, and to processes for preparing paper pulp and for manufacturing paper or board.
Pitch is the name given by paper manufacturers to the substance, derived from wood resins, which accumulates on the wire mesh belts, or "wires", of paper making machines and on the rolls and dewatering felts. The pitch deposits are sticky and can block holes in the wire thus reducing drainage through the wire, and can also reduce the absorptive capacity of the felt. They can pick fibres from the formed paper web, often causing holes or weak areas, and occasionally appear in the paper as brown lumps or patches.
Pitch is a mixture of chemical compounds of which the principal components which can be extracted by means of organic solvents are organic acids, for example fatty and resin acids, and neutral organic material such as fats. It is possible to simulate pitch in the laboratory in order to investigate means for the control of pitch in preparing paper pulp and in paper making by preparing mixtures of oleic acid and triolein in various proportions, according to the relative proportions of organic acids and neutral organic material in the pitch which it is required to model. The oleic acid has been found to mimic the behaviour of the organic acids in the pitch, and the triolein that of the neutral organic material.
Both hardwoods and softwoods contain fatty acids and neutral organic materials, but only softwoods contain significant amounts of resin acids. This latter material occurs in wood mainly in the ray cells and resin canals or ducts. Softwoods or gymnosperms such as pine, spruce and fir, therefore, in general cause more serious pitch problems than hardwoods such as birch, maple, oak and poplar. Certain species of pine are particularly rich in resin acids.
The process by which the paper pulp is prepared is also important. The wood may be reduced to pulp by mechanical grinding alone, or with the aid of a chemical cooking process. The two most important chemical cooking processes are the sulphite process in which the ground wood is cooked in an acid solution of calcium bisulphite saturated with sulphur dioxide, and the sulphate or Kraft process in which the cooking is performed in an alkaline solution comprising sodium hydroxide, sodium sulphide and sodium hydrosulphide.
When pulp is prepared by the sulphate process the pitch problem is less severe than when the pulp is prepared by the mechanical or sulphite processes because, in the sulphate process, the cooking solution is alkaline and most of the pitch-forming material is saponified and removed in solution by washing.
Two methods are presently used for controlling pitch in preparing paper pulp and in paper making. In the first method, an adsorbent material is introduced which will adsorb the pitch in the form of small droplets, generally smaller than about 2ym in diameter.
Adsorbent materials which have been used for this purpose include bentonite, talc and diatomaceous silica. In the second method, the pitch is chemically stabilised so that it remains in suspension in process water and is removed from the process.
EP-A-0586755 describes a process for controlling the deposition of pitch in a pulping or paper making process, wherein there is incorporated into the composition comprising paper making fibres up to 1.0% by weight, based on the weight of dry fibres in the composition, of a cationic polyelectrolyte which is a poly(diallyl di(hydrogen or lower alkyl) ammonium salt) having a number average molecular weight greater than 500,000. There may also be incorporated into the composition comprising paper making fibres up to 5.0t by weight, based on the weight of dry fibres, of a smectite clay.
According to a first aspect of the present invention, there is provided a pitch control agent, for use in a paper making composition, which pitch control agent comprises a smectite clay modified so as to have monovalent exchangeable cations present in an equivalent ionic fraction in the range of from 0.20 to 0.60, a first type of divalent exchangeable cations present in an equivalent ionic fraction in the range of from 0.40 to 0.80, and a second type of divalent exchangeable cations present in an equivalent ionic fraction in the range of from 0.00 to 0.20, wherein the first type of divalent exchangeable cations comprises calcium and the second type of divalent exchangeable cations comprises magnesium.
The monovalent exchangeable cation is preferably sodium or lithium, or alternatively both, and the exchangeable cations are preferably present in equivalent ionic fractions given by the ranges: monovalent exchangeable cations 0.30 to 0.50, calcium 0.50 to 0.70 and magnesium 0.00 to 0.10. Most preferably the monovalent exchangeable cation is lithium.
In a preferred embodiment, the smectite clay comprises montmorillonite. The smectite clay may be a bentonite, a major proportion of which bentonite comprises montmorillonite. Bentonite is a naturally occurring mineral which consists predominantly of montmorillonite.
The pitch control agent is preferably used in an amount such that there is present from about 0.05t to about 5% by weight of modified smectite clay, based on the weight of dry paper making fibres in the paper making composition.
The equivalent ionic fractions are determined by measuring the proportions of exchangeable sodium, magnesium and calcium ions in a sample of modified smectite clay in milliequivalents per 100g of dry smectite clay. As mentioned above, the smectite clay may be a bentonite. The equivalent ionic fraction of each of the three exchangeable cations is calculated by dividing the exchangeable proportion of that cation by the sum of the exchangeable proportions of all three cations.For example, the equivalent ionic fraction of exchangeable sodium cations in a sample of smectite clay is given by the formula:
where ha is the equivalent ionic fraction of the exchangeable sodium cation and PNa, PCa, Pw are the proportions of exchangeable sodium, calcium and magnesium cations, respectively.
The proportions of exchangeable cations of exchangeable monovalent cation, calcium and magnesium in the modified smectite clay can be determined by the following method. A sample of the smectite clay is mixed with distilled water to form a suspension containing 1 by weight of smectite; the precise solids concentration of the suspension is determined accurately by evaporating two aliquots of the suspension to dryness at 1100C for 4 hours on stainless steel dishes. Two aliquots of the smectite clay suspension, one designated "Control" and the other designated "Sample", are taken and each placed in a glass jar with a screw-top lid.The volume of these aliquots is about 20cm3 and the weight of the "Sample" aliquot is recorded accurately. 3.lg of ammonium acetate is added to the "Sample" aliquot to give an ammonium acetate concentration of about 2.Omol.dm3.
The pH of the "Sample" aliquot after the addition of the ammonium acetate is normally about 7.2+0.1. The pH of the "Control" aliquot, which is usually in the alkaline region, is adjusted to a value of 7.2+0.1 by the addition of a solution of acetic acid of concentration 3% by volume. The "Control" and "Sample" aliquots are left to stand for 16 hours and then filtered by means of a stainless steel pressure filtration device fitted with a 0.1ym membrane filter. A known volume of the filtrate from the "Control" aliquot is pipetted into a 20cm3 volumetric flask and distilled water is added up to the mark. This "Control" solution is analysed for monovalent exchangeable cation, calcium and magnesium content by inductively coupled plasma (ICP) spectrometry.A known volume of the filtrate from the "Sample" aliquot is evaporated to dryness in order to volatilise any excess ammonium acetate. The residue of this evaporation is transferred to a 20cm3 volumetric flask and distilled water is added up to the mark. This "Sample" solution is also analysed for exchangeable monovalent cation, calcium and magnesium content by means of ICP spectrometry. From a knowledge of the solids concentration of the original smectite clay suspension and the volumes of the "Control" and "Sample" filtrates taken for analysis by ICP spectrometry, the proportions of the exchangeable monovalent, calcium and magnesium cations are determined.
The efficiency of the smectite clay as a pitch control agent is determined by a procedure in which a fatty acid is used to simulate the type of pitch which is often present in a paper making composition. In each case a sample of the smectite clay under test is mixed with water to form a suspension containing 1% by weight of smectite clay and an ethanolic solution containing a known weight of oleic acid is mixed with the suspension. The resultant mixture, in which the oleic acid is in the form of an oil-in-water emulsion, is then centrifuged and the supernatant liquid is analysed for oleic acid by high performance liquid chromatography (HPLC).
According to a second aspect of the present invention, there is provided the use of a pitch control agent according to the first aspect of the invention in a paper making composition, wherein the smectite clay is present in an amount of from about 0.05k to about 5% by weight, based on the weight of dry paper making fibres in the composition.
According to a third aspect of the present invention, there is provided a paper making composition including a pitch control agent of the first aspect of the invention.
According to a fourth aspect of the present invention, there is provided a process for preparing a pitch control agent comprising a modified smectite clay, which method comprising mixing:
(a) a smectite clay having exchangeable cations substantially all of which are monovalent;
(b) an amount of a compound having a first type of divalent exchangeable cations effective to provide an equivalent ionic fraction of the first type of divalent exchangeable cations in the range of from 0.40 to 0.80; and
(c) an amount of a compound having a second type of divalent exchangeable cations effective to provide an equivalent ionic fraction of the second type of divalent exchangeable cations in the range of from 0.00 to 0.20.
The starting material smectite clay is preferably a bentonite. The first type of divalent exchangeable cat ions are preferably calcium ions and the second type of divalent exchangeable cat ions are preferably magnesium ions.
The calcium and magnesium compounds are preferably present as their chlorides and are preferably water soluble.
The invention is illustrated by the following
Example.
Example
A sample of a Wyoming sodium bentonite was divided into two large, 3000g, portions. One of these portions was mixed with 117000ml of distilled water by means of a low shear, laboratory paddle mixer. Sufficient lithium chloride was added, in powder form, to this bentonite suspension, in order to replace all of the exchangeable sodium ions with lithium, and the resultant suspension was stirred continuously for a further 30 minutes. The suspension was then filtered and the filter cake dried for 16 hours at 80"C and pulverised in a pestle and mortar. This lithium bentonite and the other 3000g portion of the sodium bentonite were divided into thirty small portions of 200g each and each small portion was mixed with 7800ml of distilled water by means of a low shear, laboratory paddle mixer.Different amounts of calcium chloride dihydrate in powder form, and in some cases also of magnesium chloride, were added to replace different proportions of the exchangeable monovalent ions with calcium and/or magnesium ions and the resultant suspension was stirred continuously for a further 30 minutes.
The suspension was then filtered and the filter cake dried for 16 hours at 80"C and pulverised in a pestle and mortar. Each of the thirty portions of treated bentonite was then analysed for exchangeable monovalent, calcium and magnesium ions by the method described above.
Each portion of treated bentonite was mixed with water to form a suspension containing 1% by weight of the dry bentonite and to 100g portions of this suspension were added 10cm3 portions of solutions in ethanol of a wide range of different quantities of oleic acid, which is considered to be a realistic model for the type of pitch which is found in suspension in paper making stock.
On the addition of the oleic acid ethanolic solution to the suspension, the oleic acid spontaneously emulsified into an oil-in-water emulsion.
This is the form of the oleic acid in the paper making stock.
There was used as a control 100g of a suspension containing 1.00g of a conventional pitch control agent which was a finely ground talc having a mean particle diameter of l.65m and a specific surface area of 13 .6m2g1.
In each case, the suspension of the pitch control agent was shaken with the oil-in-water emulsion of oleic acid for 7.5 minutes after which a 40cm3 sample of the suspension was centrifuged and 20cm3 of the supernatant liquid was pipetted into a vial. The water and ethanol were removed from the sample contained in the vial in a vacuum oven at 60-800C and a known volume of a solution containing 0.2 mol.dm-) of NaClO4.H2O in methanol was added to the vial by pipette. When the oleic acid was fully dissolved three equal consecutive injections of the resultant solution were made into a
HPLC column which was maintained at a temperature of 400C, the back pressure being 16.2MPa. For each of the three injections the area of the characteristic peak for oleic acid was measured and the mean of the three measurements calculated.
For each concentration of oleic acid in ethanol a control experiment was performed by mixing a locum3 portion of the oleic acid solution with 99g of water.
The resultant solution was treated in accordance with the procedure described above in connection with the samples containing the mineral material, with the exception of the centrifuging step, and the mean of three measurements of the characteristic peak for oleic acid was obtained.
From the two mean results the weight of oleic acid adsorbed by a given weight of the mineral material was calculated.
A graph was drawn for each portion of treated bentonite of the weight of oleic acid adsorbed per gram of bentonite against the concentration of oleic acid in each sample solution, and it was found that the weight of oleic acid adsorbed by the bentonite increased with oleic acid concentration until a plateau value was reached above which substantially no further increase was observed.
The plateau values of the amounts of oleic acid adsorbed for the various portions of treated bentonite, together with the equivalent ionic fraction of exchangeable sodium, calcium and magnesium in the bentonite portions, are given in Table 1 below.
Table 1
Equivalent ionic fractions of Oleic acid absorbed by exchangeable cations in bentonite bentonite (mo1.g-1) with monovalent
cation =
Monovalent Ca+ Mg+ Na+ Li+ cation 0.00 0.80 0.20 182 182 0.00 0.20 0.80 246 246 0.10 0.77 0.13 214 nd 0.13 0.65 0.23 197 nd 0.20 0.00 0.80 259 270 0.20 0.80 0.00 352 438 0.28 0.31 0.41 257 nd 0.32 0.36 0.32 285 nd
0.40 0.00 0.60 225 247
0.40 0.60 0.00 396 554
0.47 0.24 0.29 219 nd
0.60 0.00 0.40 178 211
0.60 0.40 0.00 293 432
0.80 0.00 0.20 109 146
0.80 0.20 0.00 147 299
Note: "nd" = not determined
As a comparison, the amount of oleic acid adsorbed by the talc was 101 Cimol.g-l.
These results show that the treated bentonite has the greatest capacity for adsorbing oleic acid, and therefore the greatest effectiveness as a pitch control agent, when the equivalent ionic fraction for exchangeable monovalent cations is in the range from 0.2 to 0.6, the equivalent ionic fraction for exchangeable calcium cations is in the range from 0.8 to 0.4 and the equivalent ionic fraction for exchangeable magnesium cations is substantially zero.
The results also show that the treated bentonite has the greatest capacity for adsorbing oleic acid, and therefore the greatest effectiveness as a pitch control agent, when the exchangeable monovalent cation is lithium, rather than sodium.
Claims (16)
1. A pitch control agent, for use in a paper making composition, which pitch control agent comprises a smectite clay modified so as to have monovalent exchangeable cations present in an equivalent ionic fraction in the range of from 0.20 to 0.60, a first type of divalent exchangeable cations present in an equivalent ionic fraction in the range of from 0.40 to 0.80, and a second type of divalent exchangeable cations present in an equivalent ionic fraction in the range of from 0.00 to 0.20, wherein the first type of diva lent exchangeable cations comprises calcium and the second type of divalent exchangeable cations comprises magnesium.
2. A pitch control agent according to claim 1, wherein the smectite clay comprises montmorillonite.
3. A pitch control agent according to claim 2, wherein the smectite clay is a bentonite, a major proportion of which comprises montmorillonite.
4. A pitch control agent according to any one of the preceding claims, wherein the monovalent exchangeable cations comprise lithium ions.
5. A pitch control agent according to any one of the preceding claims, wherein the monovalent exchangeable cations comprise sodium ions.
6. A pitch control agent according to any one of the preceding claims, wherein the monovalent exchangeable cations are present in an equivalent ionic fraction in the range of from 0.30 to 0.50.
7. A pitch control agent according to any one of the preceding claims, wherein the first type of divalent exchangeable cations are present in an equivalent ionic fraction in the range of from 0.50 to 0.70.
8. A pitch control agent according to any one of the preceding claims, wherein the second type of divalent exchangeable cations are present in an equivalent ionic fraction in the range of from 0.00 to 0 10.
9. The use of a pitch control agent, as claimed in any one of the preceding claims, in a paper making composition, wherein the pitch control agent is used in an amount such that there is present from about 0.05% to about 5% by weight of modified smectite clay, based on the weight of dry paper making fibres, in the composition.
10. A paper making composition including a pitch control agent as claimed in any one of claims 1 to 8.
11. A paper making composition according to claim 10, containing an amount of pitch control agent such that there is present from about 0.05% to about 5% by weight of modified smectite clay, based on the weight of dry paper making fibres in the composition.
12. A process for preparing a pitch control agent comprising a modified smectite clay, which method comprises mixing:
(a) a smectite clay having exchangeable cations,
substantially all of which are monovalent;
(b) an amount of a compound having a first type
of divalent exchangeable cations effective to
provide an equivalent ionic fraction of the
first type of divalent exchangeable cations
in the range of from 0.40 to 0.80; and
(c) an amount of a compound having a second type
of divalent exchangeable cations effective to
provide an equivalent ionic fraction of the
second type of divalent exchangeable cations
in the range of from 0.00 to 0.20.
13. A process according to claim 12, wherein the smectite clay is a bentonite.
14. A process according to claim 12 or 13, wherein the first type of divalent exchangeable cations are calcium ions.
15. A process according to any one of claims 12 to 14, wherein the second type of divalent exchangeable cations are magnesium ions.
16. A pitch control agent, according to claim 1, substantially as described in the foregoing Example.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9501406A GB2297334A (en) | 1995-01-25 | 1995-01-25 | Agent for controlling the deposition of pitch in papermaking |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9501406A GB2297334A (en) | 1995-01-25 | 1995-01-25 | Agent for controlling the deposition of pitch in papermaking |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9501406D0 GB9501406D0 (en) | 1995-03-15 |
| GB2297334A true GB2297334A (en) | 1996-07-31 |
Family
ID=10768514
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9501406A Withdrawn GB2297334A (en) | 1995-01-25 | 1995-01-25 | Agent for controlling the deposition of pitch in papermaking |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2297334A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001004417A1 (en) * | 1999-07-09 | 2001-01-18 | Naintsch Mineralwerke Gmbh | Use of talcum in the manufacture of paper and a method for the same |
| WO2003027017A1 (en) * | 2001-09-27 | 2003-04-03 | Rohm And Haas Company | Modified clays and methods for making and using the same |
| DE102004060587A1 (en) * | 2004-12-16 | 2006-07-06 | Süd-Chemie AG | Bentonites for impurity binding in papermaking |
| US7303654B2 (en) | 2002-11-19 | 2007-12-04 | Akzo Nobel N.V. | Cellulosic product and process for its production |
| WO2014195478A1 (en) * | 2013-06-07 | 2014-12-11 | Imerys Minerals Limited | Compositions for bleaching pulps and their use |
| EP3128073A1 (en) | 2015-08-06 | 2017-02-08 | Clariant International Ltd | Composite material for combating impurities in the manufacture of paper |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2224019A (en) * | 1988-06-29 | 1990-04-25 | Eec Int Ltd | Pitch control in papermaking |
| WO1993013265A1 (en) * | 1991-12-21 | 1993-07-08 | Vinings Industries Inc. | Method for controlling pitch |
| JPH0665892A (en) * | 1992-08-19 | 1994-03-08 | Mizusawa Ind Chem Ltd | Pitch adsorbent |
| EP0586755A1 (en) * | 1992-07-02 | 1994-03-16 | Ecc International Limited | A process for controlling the deposition of pitch in paper making |
-
1995
- 1995-01-25 GB GB9501406A patent/GB2297334A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2224019A (en) * | 1988-06-29 | 1990-04-25 | Eec Int Ltd | Pitch control in papermaking |
| WO1993013265A1 (en) * | 1991-12-21 | 1993-07-08 | Vinings Industries Inc. | Method for controlling pitch |
| EP0586755A1 (en) * | 1992-07-02 | 1994-03-16 | Ecc International Limited | A process for controlling the deposition of pitch in paper making |
| JPH0665892A (en) * | 1992-08-19 | 1994-03-08 | Mizusawa Ind Chem Ltd | Pitch adsorbent |
Non-Patent Citations (1)
| Title |
|---|
| WPI Abstract Accession No.94-115673/14 & JP 06 065 892 A * |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001004417A1 (en) * | 1999-07-09 | 2001-01-18 | Naintsch Mineralwerke Gmbh | Use of talcum in the manufacture of paper and a method for the same |
| WO2003027017A1 (en) * | 2001-09-27 | 2003-04-03 | Rohm And Haas Company | Modified clays and methods for making and using the same |
| US7303654B2 (en) | 2002-11-19 | 2007-12-04 | Akzo Nobel N.V. | Cellulosic product and process for its production |
| DE102004060587A1 (en) * | 2004-12-16 | 2006-07-06 | Süd-Chemie AG | Bentonites for impurity binding in papermaking |
| WO2006063682A3 (en) * | 2004-12-16 | 2007-01-25 | Sued Chemie Ag | Bentonite for binding impurities during paper production |
| WO2014195478A1 (en) * | 2013-06-07 | 2014-12-11 | Imerys Minerals Limited | Compositions for bleaching pulps and their use |
| US10683613B2 (en) | 2013-06-07 | 2020-06-16 | Imertech Sas | Compositions for bleaching pulps and their use |
| EP3128073A1 (en) | 2015-08-06 | 2017-02-08 | Clariant International Ltd | Composite material for combating impurities in the manufacture of paper |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9501406D0 (en) | 1995-03-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |