MXPA99004290A - Coated printing paper and method of manufacture - Google Patents

Abstract

The invention provides a novel high gloss printing paper coated with a coating composition containing at least 80 parts precipitated calcium carbonate (PCC) and at least 5 parts hollow sphere plastic pigment, parts based on total weight of pigment. Preferably, the coating composition further contains titanium dioxide. A method of making a novel printing paper is also provided.

Description

Precipitated calcium carbonate has an average size of Tf # ^ 'particle of approximately 0.6 μm, a surface area of approximately 10m2 / g and a dimensional ratio of 2: 1 to 3: 1. When the average particle size of the plastic pigment of the hollow sphere is about 1.0 miera and the hollow volume is about 55%, it means that the size of the plastic pigment particle of the hollow sphere may have, among other measures, 0.8 or 0.9 microns, also the hollow volume can have the value of 50%, which is approximately 55%. - «- When the average particle size of the plastic pigment of the hollow sphere is 1.0 microns and the hollow volume is 55%, it is obvious to a person skilled in the art that the empty diameter is 0.82 microns, also if the hollow volume is 50% the empty diameter is 0.80 microns, so when the average particle size is 0.9 microns and the hollow volume is 55%, the empty diameter is 0.49 microns, but with a hollow volume of 50 %, the empty diameter is 0.45 microns. When the particle size is 0.8 microns and the hollow volume is 55%, the empty diameter is 0.44 microns and when the hollow volume is 50% the empty diameter is 0.4 microns. The preferred mode is when the hollow sphere plastic pigment has an average particle diameter of about 1.0 micron and an empty volume of about 55% and therefore an empty diameter of 0.82 micron. The invention further provides a method for making glossy printed paper by applying a layer of coating composition to at least one surface of a paper substrate, the coating composition comprising at least 80 parts of precipitated calcium carbonate and At least 5 parts of hollow sphere plastic pigment, the method consists of drying the coated substrate and calendering the dry coated substrate. The method can also incorporate the other coating compositions described. Other objects and advantages of the invention will be apparent to those skilled in the art from the following detailed description of the preferred embodiments of the invention.

DESCRIPTION OF THE PREFERRED MODALITIES OF THE INVENTION The glossy printing paper of the present invention is made by coating a paper substrate with a coating composition comprising at least 80 parts of precipitated calcium carbonate (hereinafter referred to simply as PCC) and at least 5 parts of hollow sphere plastic pigment, based on 100 parts by weight of the total pigment.

The use in combination, according to the present invention, of at least 80 parts of PCC and at least 5 parts of hollow plastic pigment, unexpectedly produced a printed paper with superior quality characteristics and substantially improved printing capacity. The combination provides improved interaction between coating and ink, better absorption, better absorption of source solution, as well as a uniform smooth surface with high luster and high gloss. The resulting printed image has a high ink luster, high ink uniformity and low microlustre. The printing paper of the invention also exhibits excellent resistance to blistering. The improved printing and corrugating capability of the paper is demonstrated by the substantial elimination of the problems of glue pick-up, marking and scratching. The coating composition of the invention comprises at least 80 parts by weight of PCC and at least 5 parts by weight of hollow sphere plastic pigment. Examples of suitable PCCs include Albaglos L and Albaglos S, manufactured by Specialty Minerals, Inc. The PCC preferably has an average particle size of about 0.6 μm and a surface area of about 10 m2 / g. More preferably, the PCC has a dimensional relationship in the range of 2: 1 to 3: 1. Suitable hollow sphere plastic pigments are obtained from Rohm & amp;; Haas Company, with the names Ropaque HP-1055, OP-96 and HP-91. Preferably, the hollow sphere plastic pigment has an average particle diameter of about 1.0 μm and a hollow volume of about 55%. More preferably, the hollow sphere plastic pigment is composed of an acrylic styrene polymer. The coating composition of the invention may further comprise less than 6 parts by weight of clay. Those experienced in the field will know that the use of clay in coating compositions will decrease the gloss while improving other properties. In contrast, the addition of clay in the present invention also unexpectedly reduces the luster of the paper and other attributes of the final product. The desired attributes in the final product will determine the amount of clay used in these coating formulations. Examples of suitable clays include Astra-Plus, available from ECCI and Ansilex 93 available from Engelhard Coporation. Preferably, the coating compositions of the invention also comprise natural or synthetic non-clay pigments, either alone or as a mixture. Examples of suitable pigments include titanium dioxide, in both anatase and rutile form, aluminum hydroxide, satin white, silica, organic pigments, etc. It should be understood that these pigments are listed by way of example and the pigments used for this invention are not limited to those mentioned in the list. More preferably, the pigment that is not clay is titanium dioxide. An example of suitable anatase titanium dioxide is TiONA-A2000, available from SCM Chemicals. The preferred coating composition comprises 80 to 92 parts of PCC and 6 to 12 parts of hollow sphere plastic pigment, the parts are given based on the total weight of the pigment. For products that require high opacity, the most preferred coating composition comprises from 80 to 84 parts of PCC, 6 to 12 parts of hollow sphere plastic pigment and 9 to 12 parts of titanium dioxide, the parts are given with base in the total weight of the pigment. Otherwise, the most preferred coating composition, balancing both the quality of the final product and the production cost, comprises 85 to 92 parts of PCC, 8 to 12 parts of hollow sphere plastic pigment and less than 6 parts of dioxide of titanium, the parts are given based on the total weight of the pigment.

The coating compositions of the invention are suitable for printing degrees both in sheet and in plot, without modifications. The skilled practitioners of this technique know that the coating compositions in general must be modified for plot grades, due to the speeds and high temperatures involved in the screen printing. Raster printing papers tend to have more porous and less damp coating layers to reduce blistering during drying. The coating composition of the invention further comprises a binder system required for all paper coatings. Those with expertise in this field will know that a binder system with starch will decrease the brightness. It is preferred to use a latex binder system with minimal amounts of starch. Latex binders that can be used in the invention include acrylic, styrene-butadiene, styrene-acrylate, urethane-acrylonitrile, carboxylated networks, etc. It should be understood that these binders are mentioned only as an example and that the binders used for this invention are not limited to those mentioned in the list. Preferably, a mixture of two types of latex, styrene-butadiene and styrene-acrylate, is the one used in the invention.

L Practitioners with experience in this field know that the coating formulations can include a variety of additives, for example dyes, fluorescent brighteners, dispersants, thickeners, lubricants, pH control agents, etc. The use of coating additives is determined by the attributes of the final product. It should be understood that the invention is not limited to the additive components mentioned in the list. The substrate of the paper of the invention is obtained by conventional papermaking techniques using any paper fiber. Preferably, the paper substrate will be free of wood. Those with expertise in this field will understand that the attributes of the final product and the factors of productivity will determine the particular mixture of paper fibers used. In addition, the substrate preferably is prepared with a pre-coating of starch. The coating composition of the invention can be applied by a variety of coating technologies. Examples of coating applications include bent bent sheet, beveled applicator blade, rod, short stay, curtain coating, air knife, etc. Experienced practitioners in this field will know that invention is not limited to these techniques. In addition, those skilled in the art know that modifications to the rheology of the coating compositions of the invention will be necessary depending on the coating technique employed. The most preferable method for applying the composition of the invention is carried out with a folded type coater and a dry coating weight of 8.9 to 16.3 g / m2 (6 to 11 pounds / 3300 ft2) per side. However, the invention includes coated paper products on only one side, as well as double coating products on one side or both sides. Experienced practitioners in this field will recognize that both the rheology and coating weights applied will vary depending on the final attributes of the product that are desired. In addition, the coating operation can be done in a continuous line operation with the papermaking operation. The invention includes the finishing step consisting of the calendering of the dry coated paper. The calendering method of the paper of the invention is not restrictive. The paper may be calendered as a separate step, on a self-supporting calender or super-floater, or it may be calendered in a continuous operation in line with the papermaking operation and / or the coating operation. The following examples illustrate the invention and allow those skilled in the art to understand the invention. It should be understood that the invention is not limited to the particular examples given below. Unless stated otherwise, all parts and percentages are given by weight. Table 1 mentions the list of formulations and final attributes of the product both of the invention and of the comparative examples. Examples 1 to 5 illustrate the present invention. Examples Cl to C3 are mentioned as a comparison. All coating compositions were mixed in laboratory-sized batches with a final coating solids content of 58 to 60%. The raw material with a basis weight of 71.0 g / m2 (48 pounds / 3300 ft2) was coated on one side with each coating. The final coated weight was approximately 14.8 g / m2 (10 pounds / 3300 ft2). The coated and dried samples were calendered in a laboratory calender, through a roller contact point at high pressure and high temperature. The tests were carried out after the samples had been conditioned for 24 hours at a constant humidity of 50%.

Table 1 The microlust is a measure of the point-to-point variation in luster and this measure is related to the quality of the image. It is measured using a 1.5 mm microlustre head in the Tobias Mottle tester. The smaller the value, the more uniform is the luster on the surface.

The embodiments of the invention illustrated by the examples balance the desired final attributes of the product which consist of high gloss, high luster of the paper, high luster of the ink and low microlustre. While the preferred forms of the invention have been described and illustrated in the examples, the experts will obviously be able to see other variations. The invention is not limited to the modalities and modifications that can be made without departing from the spirit of the invention and the scope of the appended claims.

Claims (30)

1. CLAIMS. 1. A glossy paper for printing with improved printing qualities comprising a paper with at least one surface covered with a layer of a coating composition, which consists essentially of: a) at least 80 parts of precipitated calcium carbonate and b ) at least 5 parts of a hollow sphere plastic pigment having a size in the range of 0.8 to 1.0 microns. Each particle of hollow sphere plastic pigment contains a different internal hollow, whose diameter is about 0.45 microns to about 0.82 microns and a hollow volume of about 50% to 55%, the parts are based on 100 parts by weight of the total pigment .
2. 2. A glossy printing paper according to claim 1, wherein the coating composition comprises from 80 to 92 parts of precipitated calcium carbonate and from 6 to 12 parts of hollow-sphere plastic pigment, the parts are given based on 100 parts by weight of the total pigment.
3. 3. A glossy printing paper according to claim 1 or 2, wherein the coating composition further comprises other natural or synthetic non-clay pigments.
4. 4. A glossy printing paper according to claim 3, wherein at least one of the other natural or synthetic non-clay pigments is titanium dioxide.
5. 5. A glossy printing paper according to claim 4, wherein the coating composition comprises 80 to 84 parts of precipitated calcium carbonate, 6 to 12 parts of hollow-sphere plastic pigment and 9 to 12 parts of titanium dioxide, the parts are given based on 100 parts by weight of the total pigment.
6. 6. A glossy printing paper according to claim 4, wherein the coating composition comprises 85 to 92 parts of precipitated calcium carbonate, 8 to 12 parts of hollow-sphere plastic pigment and less than 6 parts of titanium dioxide, the parts are given based on 100 parts by weight of the total pigment.
7. 7. A glossy printing paper according to claim 1 or 2, wherein the weight of the dry coating of the layer of the coating composition is 6 to 11 pounds / 3300 ft2.
8. 8. A glossy paper for printing according to claim 1 or 2 characterized in that the hollow sphere plastic pigment has an average diameter of 0.8 to 1.0 microns.
9. 9. A glossy printing paper according to claim 1 or 2, wherein the hollow sphere plastic pigment is composed of an acrylic styrene copolymer.
10. 10. A glossy printing paper according to claim 1 or 2, wherein the precipitated calcium carbonate has an average particle size of about 0.6 μm and a surface area of about 10 m2 / g.
11. 11. A glossy printing paper according to claim 1 or 2, wherein the precipitated calcium carbonate has a dimensional ratio ranging from 2: 1 to 3: 1.
12. 12. A glossy printing paper with improved printing capability comprising a paper substrate coated on at least one surface with an upper layer of coating composition comprising at least 80 parts of precipitated calcium carbonate, at least 5. parts of hollow sphere plastic pigment and less than 6 parts of clay, the parts are given based on 100 parts by weight of the total pigment.
13. 13. A glossy printing paper according to claim 12, wherein the coating composition comprises from 80 to 92 parts of precipitated calcium carbonate and 6 to 12 parts of hollow-sphere plastic pigment, the parts are given based on 100 parts by weight of total pigment.
14. 14. A glossy printing paper according to claim 12 or 13, wherein the coating composition further comprises other natural or synthetic non-clay pigments.
15. 15. A glossy printing paper according to claim 14, wherein at least one of the other natural or synthetic non-clay pigments is titanium dioxide.
16. 16. A glossy printing paper according to claims 12 or 13, wherein the weight of the dry coating on the layer of the coating composition is 6 to 11 pounds / 3300 ft2.
17. 17. A glossy paper for printing according to claims 12 or 13, characterized in that the hollow sphere plastic pigment has an average diameter of 0.8 to 1.0 microns.
18. 18. A glossy printing paper according to claim 12 or 13, wherein the hollow sphere plastic pigment is composed of an acrylic styrene copolymer.
19. • 19. A glossy printing paper according to claims 12 or 13, wherein the precipitated calcium carbonate has an average particle size of about 0.6 μm and a surface area of about 10 m2 / g.
20. 20. A glossy printing paper according to claim 12 or 13, wherein the precipitated calcium carbonate has a dimensional ratio of 2: 1 and 3: 1.
21. 21. A method for manufacturing a lustrous paper for printing with improved printing qualities, which consists of: Applying a surface layer of a coating composition to at least one of the surfaces of a substrate paper, said coating composition comprising: a . at least 80 parts of precipitated calcium carbonate and, b. at least 5 parts of a hollow sphere plastic pigment having a size in the range of 0.8 to 1.0 microns. Each particle of hollow sphere plastic pigment contains a different internal hollow, whose diameter is about 0.45 microns to about 0.82 microns and a hollow volume of about 50% to 55%, the parts are based on 100 parts by weight of the total pigment .
22. 22. The method for manufacturing a glossy printing paper according to claim 21, wherein the coating composition comprises 80 to 92 parts of precipitated calcium carbonate and 6 to 12 parts of hollow-sphere plastic pigment, the parts are given with base to 100 parts by weight of the total pigment particles.
23. 23. The method for manufacturing a glossy printing paper according to claims 21 or 22, wherein the coating composition further comprises other natural or synthetic non-clay pigments.
24. 24. The method for manufacturing a glossy printing paper according to claim 23, wherein at least one of the other natural or synthetic non-clay pigments is titanium dioxide.
25. 25. The method for manufacturing a glossy printing paper according to claim 24, wherein the coating composition comprises 80 to 84 parts of precipitated calcium carbonate, 6 to 12 parts of hollow sphere plastic pigment and 9 to 12 parts. of titanium dioxide, the parts are given based on 100 parts by weight of the total pigment.
26. 26. A method for manufacturing a glossy printing paper according to claim 24, wherein the coating composition comprises 85 to 92 parts of precipitated calcium carbonate, 8 to 12 parts of hollow-sphere plastic pigment and less than 6 parts. parts of titanium dioxide, the parts are given based on 100 parts by weight of the total pigment.
27. 27. A method for the production of a glossy printing paper with improved printing capacity consisting of: a. applying an upper layer of coating composition to at least one surface of a paper substrate, the coating composition comprising at least 80 parts of precipitated calcium carbonate, at least 5 parts of hollow-sphere plastic pigment and less of 6 parts of clay, the parts are given based on 100 parts by weight of the total pigment, b. dry the coated substrate and c. calendering the dry coated substrate.
28. 28. A method for manufacturing a glossy printing paper according to claim 21, wherein the coating composition comprises 80 to 92 parts of precipitated calcium carbonate and 6 to 12 parts of hollow-sphere plastic pigment, the parts being give based on 100 parts by weight of total pigment.
29. 29. The method for manufacturing a glossy printing paper according to claim 27 or 28, wherein the coating composition further comprises other natural or synthetic non-clay pigments.
30. 30. The method for manufacturing a glossy printing paper according to claim 29, wherein at least one of the other natural or synthetic non-clay pigments is titanium dioxide.