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(11) | EP 0 044 695 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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Blends of algin, tamarind, and a polycationic electroconductive polymer Mischungen von Natriumalginat, Tamarindenkernmehl und einem polykationischen elektroleitenden Polymer Mélanges d'algine, de tamarin et d'un polymère électroconducteur polycationique |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] Blends of algin and tamarind have recently been described in U.S. Patent No. US-A-4,257,768 and in EPO Application No. 79302481.1 (EP-A-0 011 434). The blend was taught to be useful in paper coatings.
[0002] The polycationic electroconductive polymer used is Conductive Polymer 261, a homopolymer of dimethyl diallyl ammonium chloride, which is sold by Calgon Corporation and described in U.S. Patent No. 3,288,770, and Tappi, Vol. 50, No. 1, 1967, pp. 26-31. This is a linear repeating-ring polymer having quaternary ammonium salt groups on the backbone.
[0003] It has now been found that blends of the algin-tamarind with Conductive Polymer 261 improve the water retention, film-forming, release (less tackiness), and solvent holdout properties of the polymer. Amounts of algin-tamarind relative to the amount of total solids of polymer plus blend range from 1.5-10% by weight, preferably about 1.6-4% by weight. The best algin-tamarind blend is a 1:4 blend made as disclosed in EPO 79 302 481.1 (EP-A-0 011 434), supra. An example from that publication is as follows:
20:80 Dry blend
[0004] Sodium alginate and tamarind kernel powder are dry mixed in the weight ratio 20:80. The mix is dissolved in deionized water by heating to 74°C for 20 min. with stirring. The solution is cooled to room temperature and concentrations of 0.5%, 1% and 2% are prepared.
[0005] The present invention provides an aqueous solution comprising 12% of the said CP-261 and 0.4% of a blend of tamarind kernel powder and sodium alginate, 4:1 weight ratio.
[0006] The invention also provides a paper coated with a conductive coating comprising 90-98.5% by weight of the said homopolymer CP-261 and 1.5-10% by weight of a blend of tamarind kernel powder and sodium alginate, 4:1 weight ratio.
[0007] The blend of algin-tamarind in Conductive Polymer 261 is made by first dissolving the algin-tamarind blend in water (about 2% by weight concentration). Procedures for dissolving it involve slowly adding the blend with vigorous stirring at elevated temperatures to distilled water. Generally, a syrupy, translucent liquid results in about 15 min. This solution is then mixed with the commercial solution of Conductive Polymer 261 (generally available as a 40% aqueous solution), in amounts so that about 96-97% of the final dry coating is Polymer 261 and about 4-3% is the blend. The actual working amount of solids in the paper coating composition is about 12% solids.
[0008] This invention is illustrated by the following experimental description, in which the words Camas, Meyer and Weyerhaeuser are trade marks.
[0009] A 2% by weight solution of a dry blend (4:1) of tamarind gum:sodium alginate was prepared by slowly adding it with vigorous stirring at elevated temperatures to distilled water, and maintaining these conditions until it dissolves (about 15 min). Subsequent solution was a syrupy, translucent, tan liquid.
[0010] The other component used in the formulations was Conductive Polymer 261 (Calgon CP 261 LV) (1500 mPa.s at 22°C). The order of addition of components in each color is given in Table I. All formulations made down fairly easily with no major problems.
[0011] The blend was mixed with CP-261LV at 3:97 weight ratio (based on active solids) and compared to plain CP-261 LV in a typical size press color of 12.4% total solids. The drawdown evaluations were made on a 38-pound conditioned Camas rawstock. In each case, three drawdowns were made using a No. 3 Meyer rod and three were made using a No. 10 Meyer rod. The felt side was coated in all cases. Drawdown designations, basis weights and coat weights are listed in Table II.
[0012] The usual coating, drying and conditioning techniques were used. Coatweights were obtained using an analytical balance (before and after application of the color).
[0013] A 2% dyed toluene solution was used in the solvent holdout evaluations, using the Weyerhaeuser Chart was used to determine percent penetration.
[0014] The combinations drawn from the above data indicate that the alginate:tamarind blend does not adversely affect conductivity of the Polymer 261.
[0015] Surface resistivity measurements at 20% and 50% relative humidity were nearly identical to the respective CP-261 LV coated sheets, see Table III for additional details.
[0016] Solvent holdout properties of drawdowns coated with the CP-261 LV/alginate:tamarind blend formulations were significantly better than with CP-261LV alone, see Table III for details.
[0017] At the concentration used with CP-261 LV, the alginate:tamarind blend appeared to have a significant beneficial effect in reducing sheet tackiness. Table IV gives details of experimental results.
[0019] Lack of sheet stiffness is a common problem in conductivized reprographic papers, especially at high relative humidities. Where this occurs, one solution is to increase the basis weight of the paper, which is of economic disadvantage. A property of the blends of this invention is that they stiffen paper when applied at the levels used for coating paper.
1. An aqueous solution comprising 12% of the homopolymer of dimethyl diallyl ammonium
chloride designated CP-261 and 0.4% of a blend of tamarind kernel powder and sodium
alginate, 4:1 weight ratio.
2. A paper coated wtih a conductive coating comprising 90-98.5% by weight of the homopolymer
of dimethyl diallyl ammonium chloride designated CP-261 and 1.5-10% by weight of a
blend of tamarind kernel powder and sodium alginate, 4:1 weight ratio.
3. Paper as claimed in Claim 2 in which the conductive coating comprises 96-98.4%
by weight of the said homopolymer CP-261 and 1.6-4% by weight of the said blend of
tamarind kernel powder and sodium alginate.
1. Eine wässerige Lösung, enthaltend 12% des mit CP-261 bezeichneten Homopolymers
von Dimethyldiallylammoniumchlorid und 0,4% einer Mischung von Tamarindenkernmehl
und Natriumalginat im Gewichtsverhältnis 4:1.
2. Ein mit einer leitfähigen Schicht überzogenes Papier, dessen Schicht 90-98,5 Gew.-%
des mit CP-261 bezeichneten Homopolymers von Dimethyldiallylammoniumchlorid und 1,5-10
Gew.-% einer Mischung von Tamarindenkernmehl und Natriumalginat im Gewichtsverhältnis
4:1 enthält.
3. Papier wie in Anspruch 2 beansprucht, in welchem die leitfähige Schicht 96-98,4
Gew.-% des genannten Homopolymers CP-261 und 1,6-4 Gew.-% der genannten Mischung von
Tamarindenkernmehl und Natriumalginat enthält.
1. Solution aqueuse comprenant 12% d'un homopolymère de chlorure de diméthyldialkylammonium
désigné par CP-261 et 0,4% d'un mélange de poudre de noyau de tamarin et d'alginate
de sodium, dans un rapport pondéral de 4:1.
2. Papier couché avec une couche protectrice contenant 90-98,5% en poids d'unhomopolymère
de chlorure de diméthyldialkylammonium désigné par CP-261 et 1,5 à 10% en poids d'un
mélange de poudre de noyau de tamarin et d'alginate de sodium, dans un rapport pondéral
de 4:1.
3. Papier selon la revendication 2, dans lequel la couche conductrice contient 96
à 98,4% en poids dudit homopolymère CP-261 et 1,6 à 4% en poids dudit mélange de poudre
de noyau de tamarin et d'alginate de sodium.