JPH02503933A - paper coating - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Name of invention Paper coating Technical field The invention is suitable for printing by gravure or by offset lithography. The present invention relates to a coated paper and a method for producing the same.

Conventional technology GB-2039789 has one side of the sheet conductive and the other side smectite crystal. electrostatic image, which is a continuous insulating layer containing a mixture of - (green clay) and an electrically insulating polymer. A forming sheet is disclosed.

present invention According to a first aspect of the invention, each of the first and second particles is hydrophilic, water-absorbing and porous. a cellulosic sheet material having first and second pigmented coatings; The above first coating is the base coat and the above second coating is the top coat. pigments in one of these coatings are primarily of the non-smectite type. The pigment in the other coating contains at least 60% by weight of a water-swellable pigment. It is characterized by mainly having smectite-type properties including mectite-type clay. suitable for printing by offset lithography and/or gravure processes Paper provided.

According to a second aspect of the invention, each of the following pigmented coatings is applied to a cellulosic silicone. Offset lithography and/or gravure including the step of applying one piece of sheet material The Act provides a method for producing paper suitable for printing; (i) a first, i.e., base coat, and (ii) a second, i.e., top coat; (The pigments in one of these coatings have primarily non-smectite properties; The pigment in the other coating contains at least 60% by weight of water-swellable smectite-type pigments. (has smectite-type properties including rays).

According to a third aspect of the invention, a gravure or offset lithographic printing method is provided. A method is provided for printing an image on paper using the first and second pigment-treated coatings are water-absorbent and porous; One of the pigments in cellulose dyes has primarily non-smectite properties. but the pigment in the other coating is at least 60% by weight water-swellable smectite. It is characterized by mainly having smectite-type properties including type clay.

In order to be suitable for use in offset lithographic printing processes, the paper according to the invention must be Both the base coat and top coat are hydrophilic, absorbent and porous. Therefore, it is necessary that water be quickly carried away from the paper surface.

Description of preferred embodiments Smectite-type clays are, for example, bentonite, montmorillonite, hectora It can be ferrite, sabonite, or fuller's earth, but is particularly preferred because of its mating properties. Natural with or processed to have primarily sodium ions on the site It's bentonite. Preferably, the material mainly has the above-mentioned smectite-type properties. The pigment contains at least 75% by weight, more preferably at least 90% by weight of pigment. Contains kutite-type clay.

The pigment used in the other coating is kaolin clay, natural or synthetic carbonate. Smectites like calcium, talc or natural or synthetic calcium sulfate It is a white clay pigment.

Also other conventional pigments can be used. The pigment used in this one coating is In some cases, it may also contain small amounts of smectite-type clays.

Paper may have additional coatings. However, sheet materials are preferred. Contains two coatings, with the top coating mainly consisting of smectite-type creases. - Contains a pigment, typically bentonite, with the other coating or base coat The coating contains pigments that are substantially non-smectite in nature. deer However, within the scope of the present invention, it is understood that the pigments of the base coating are non-stop in nature. is a smectite clay and the top coating is substantially non-smectite clay. Paper is also provided. Most preferably, the base coating contains kaolin. The top coating contains bentonite.

Each coating may preferably be bonded together with an adhesive, and this t# M ffl For example, rubber latex, acrylic copolymer latex (styrene rubber) used in paper coatings such as tajene rubber latex) or starch It can be one of the usual adhesives. If the pigment is not a smectite-type resin, The amount of adhesive solids required ranges from 1 to 20 parts by weight R to 100 parts by weight of the pigment. Ru. If the pigment has mainly smectite type properties, the base coat Proper adhesion of smectite clay to cellulosic fibers is Pigments can be used without adhesives as it has been found to be achieved without the presence of adhesives. Wear. When using adhesive, latex adhesive is recommended for gravure printing paper. Agents, especially acrylic copolymer latexes, have been found to be preferred. Typically The amount of adhesive used ranges from 1 to 300 parts by weight of dry polymer to dry smectyl. It would be in the range of 100 parts by weight of Tocray.

Preferably, the pigments of the coating, which are smectite in nature, are smectite in nature. Pigments containing at least 60% by weight of water-swellable smectite clay are added to the coating material. It is prepared by applying an aqueous suspension containing at least 20% by weight.

detailed description The present invention will be explained in more detail with reference to the following examples.

Example 1 A gravure base paper with a material weight of 38gm"□2<g/m") was 2 using laboratory coating equipment of the type described in No. 03253'6. The coating was operated at a speed of 00 m-gIin-' (m7 min). next three Different coating procedures were used: 1.100 parts by weight of kaolin clay, 5 layers 57 parts of acrylic copolymer latex adhesive (dry basis) and water. ．． A single coating of the composition constitutes a suspension containing 4% total solids by weight.

Kaolin clay contains 6% by weight of particles with an equivalent spherical diameter greater than 10 microns. 43% by weight of particles having an equivalent spherical diameter smaller than 2 microns The particle size distribution was as follows. Latex is 50% by weight acrylic copolymer. It had a solid content of mer.

Each sample of base paper was coated with four different coatings of the above composition. Coated with.

2.a) European base with sodium and calcium exchangeable cations Base coat of an aqueous suspension containing 5 mfi% of tonite. Apply to base paper The coating weight of bentonite was (1.5 gm-'').

h) A topcoat of the same composition as described in 1 above with four different coatings. applied at a weight of

38a) A basecoat of the same composition as described in the above procedure was applied with four different coats. applied at ting weight.

b) A top coat of the same bentonite aqueous suspension as described in 2a) above. ．． A coating weight of 5 gm-2 was applied.

Each sample of the hand-coated sheet was tested with a gravure print. 'r'rinting Te on Winston Bruch Press cbnology, Vol. 13, Nn, 1. April 1969, 9-22 A paper published by Swan on page ^, “RealisLic paper t estsfor various prioLingprocesses' Printed using the method described. The cylinder for gravure printing has a deep edge. The etching cell gives a solid black area and the less deep etching cell gives a half black area. It was used to give a tone area. Gloss (gloss) of solid black areas of test print Ross) is the Tappi standard method (Tappi 5 standard Me Lbod) N (L'l' 480 Ls -65, solid black area The printing density of the area was measured according to the following formula: printing density = Iog 1'O (1/reflection In the above, the reflectance is the irradiation light with a wavelength of 574 nm reflected from the black area. This is the percentage of

Further measurements of print density were carried out on the back side of the paper in the solid black area, where the printing ink “ The degree of strike-through (sLrike through) was measured.

In addition, the degree of "smearing" in the halftone areas of each print is determined from the test print. This was determined by evaluating the percentage of gravure print dots that were missing. moreover The gloss of the unprinted areas of each coated paper sample was Sod N (measured with LT480ts-65. The results are not shown in Table 1 below. : These results are based on the 0.5 gm bentonite coating on the base paper. One of the coating methods is the application of a solid black printed area as a light coating. The results show that this results in an increase in print density and printing density. bentonite When applied as a base coat, the above increase is relatively small, but when applied as a vent coat, When a suspension of lye is applied as a top coat on a kaolin-containing coating, The increase in gloss and print density both increases the gloss of areas without print Even if it is not substantially affected by the existence of light, it is surprisingly large. You're talented, half. Tone print quality also varies with bentonite coordinates, as indicated by percentage of missing dots. is substantially unaffected by the presence of

Example 2 Offset base paper of material type ITh65gm-' was used in the laboratory container used in Example 1. First, 100 parts by weight of Kaolin clay, 11% by weight styrene-butadiene rubber latex° (dry basis) ), and water forming a suspension containing 60.8% total solids by weight. coated with a compound.

Kaolin clay has an equivalent spherical diameter of 0.2% by weight greater than 10 microns consisting of particles such that 10% by weight have an equivalent spherical diameter of less than 2 microns. It had a fine particle size distribution. Latex is 50% styrene butadiene rubber. It contained a shape component. Each sample of base paper has four different types with this composition. Coated with coating weight.

Each paper sample was coated with the above composition at four different coating amounts. European bentonite with sodium and calcium exchangeable cations A second coating composition consisting of a 5% suspension in water of 0.5 gm-'' of treatment amount.

Each sample of the above coated paper was tested using an IGT model AC2 printability tester. Tested for set lithography printing properties.

Each paper sample was moved by the above device, which was set to move at a constant speed of 1 m5-'. clipped to the moving sector. Aluminum alloy brake with face width 25IIllTl A rubber coated printing roll with a roll and face width of 20IIIL11 is placed on the fixed part of the above device. Rotatably and removably mounted on a spindle provided with a brake roll 70. before the paper sample surface contacts the paper surface of the printing roll. Up at mn Contact was made in the direction of relative movement between the paper adhesion sector and each roll.

As a result of this arrangement, each paper sample is a 20mm wide strip of solid color. The first 70mm II+ was printed on dry paper and the remaining 140mm was scraped off. Printed on wet paper. During operation, the brake roll is 25 kg for the paper sample. The printing roll was biased with a force of 50 kg against the paper sample. I set it. The brake roll and printing roll had an overall diameter of 68 mrQ.

Before each test, the brake roll was soaked in a substantially equivalent amount of water, i.e., per square meter of roll surface area. Approximately 0.6 g of water per roll was loaded by condensation of water vapor on the roll surface. braking Place the roll in a freezer with an internal temperature of -8±1°C and connect it to a digital thermometer. A coil-type temperature probe was placed in the center spindle hole of the roll. recorded with a thermometer When the temperature reached +5°C, the roll was heated to 55% RH and sodium dichromate. Transferred to a desiccator held by a saturated solution. Atmosphere inside thermometer When the temperature reaches +5℃, the humidity of 55% RH is changed to sodium dichromate. Transferred to a desiccator held by saturated solution. Atmosphere temperature in the laboratory was adjusted to 20±1°C. Leave the roll in a desiccator for 1 minute and 55 seconds to check printability. After a further 5 seconds the test Magenta (Ault & Wiborg 4-Co1our ProcessG Ioss MagenLa) Pre-inked with offset lithography ink This was done using a printed printing roll.

Printed solids on dry and pre-wetted areas of the paper sample, respectively. A 2.7 tarab gloss meter model with printed color blocks and a glossy finish. Using D1f3, set Tarapy Standard N (IT4) at an angle of 75° to the paper surface. 80ts-65 and the average of 5 measurements for each area was recorded.

Print solid color blocks onto dry and pre-moistened areas. Macbeth RD514 reflection densitometer was also used for printing density. In this case, the average of 10 measurements of each area was recorded.

Furthermore, the gloss of the unprinted areas of each coated paper sample is also Measured by code method NaT480ts-65.

The results are not shown in Table 2: These results are consistent with the amount of coating given the gloss of unprinted paper. Qualitatively the same, but the glossiness of the blocks of color printed on the dry area This shows that there is an increase in benefits. The print density is determined by the top of the bentonite composition. This eliminates the loss of print density on pre-wetted areas when applying a wet coat. However, there is almost no change.

Example 3 Two-stage coating of matte offset printing base paper with a material weight of 59 gm-2 I clicked. Each step was carried out using the laboratory coating equipment used in Examples 1 and 2. The operation was carried out at a speed of 00 m/min.

In the first stage, the coating composition used was 100 parts by weight of natural carbonic acid. Calcium, 11 parts by weight Styrene-butadiene rubber latex (dry basis), 0 ．． 5 parts by weight of sodium carboxymethyl cellulose, 0.61 parts by weight of sodium hydroxide Thorium and water constitute a suspension containing 66.9% total solids by weight. did.

1% by weight of natural calcium carbonate has an equivalent spherical diameter greater than 10 microns 90% by weight of particles having an equivalent spherical diameter of less than 2 microns It was a crushed marble with a particle size distribution consisting of:゛Latex weighs 50% % styrene-butadiene rubber solids.

In the second stage, the paper coated with the calcium carbonate-containing composition described above is Each sample was tested in three submerged suspensions of the same bentonite used in Examples 1 and 2. Tested in suspension. These three types of suspensions were 4% by weight, 8% by weight, and 8% by weight, respectively. It contained 12% by weight of bentonite, but in each case the actual application to paper The bentonite coating I was about 5 gm-''.

In Example 2, the same offsera as described) IJ tograph printing test was carried out in the above two stages. Calcium carbonate-containing composition on floor-coated paper samples and as a comparison It was performed on a sample coated only with the material. In addition, each coated paper prints The luster of areas that are not coated can also be improved using Tarapy Standard Method N [IT480ts-G '5. The results obtained are not shown in Table 3 below: These results are The gloss of the colored printed areas is maintained both on the dry and pre-wetted areas of the paper. As the weight percentage of bentonite in the second coating composition increases, It shows you much more than the luster of unprinted paper. on dry paper The print density of the printed solid color areas is also increased, but the pre-moistened paper The print density of the solid color printed on top remains substantially unchanged.

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Claims (17)

[Claims] 1. first and second pigment treated coats each being hydrophilic, water absorbing and porous; the first coating comprises a cellulosic sheet material having a The base coat and the second coating are the top coat, and the first coating is the top coat. The pigments in one coating have predominantly non-smectite properties, while the pigments in the other coating have predominantly non-smectite properties; The pigment of the coating is at least 60% by weight water-swellable smectite clay. A printing paper characterized in that it mainly has smectite-type properties. 2. A coating containing mainly smectite clay as a pigment is a top coat. The paper according to claim 1, which is 3. A coating containing mainly smectite clay as a pigment is a base coating. The paper according to claim 1, which is 4. The first and second coatings are the only coats applied on the sheet material. 4. The paper according to claim 1, 2 or 3, wherein the paper is 5. The sheet material has one or more additional coats between said base and top coats. 4. The paper according to claim 1, 2 or 3, comprising: 6. The coating weight of smectite clay coating is less than 5gm-2 Paper according to any one of the preceding claims, which is not many. 7. Said claim that one or both of the base and top coatings includes an adhesive. A form with one of the items requested. 8. The other coating contains at least 75% by weight of pigment of the smectite type. A paper according to any one of the preceding claims, comprising a paper. 9. The other coating contains at least 90% by weight of pigment of the smectite type. 9. The paper according to claim 8, further comprising: 10. The pigment of the base coat is mainly a white pigment other than smectite clay. Claim 2 or any one of claims 3 to 9 dependent on claim 2 paper. 11. a first and a first, each generally hydrophilic in nature and containing at least 70% by weight pigment; a cellulosic sheet material having a second coating and a second coating; the coating is a base coat and the second coating is a top coat, The pigments in the base coat are mainly non-smectite and the pigments in the top coat are small. Contains at least 60% by weight water-swellable smectite clay and from 5 gm-2 characterized by forming a coating having a coating weight that is not too much printing paper. 12. The main pigment in the base coat is a white pigment other than smectite clay. The paper according to claim 11. 13. The main pigment in the base layer is kaolin clay, natural or synthetic calcium carbonate. The paper according to claim 12, which is calcium sulfate, talc, or natural or synthetic calcium sulfate. . 14. The cellulosic sheet material is coated with each of the following pigmented coatings, viz. (i) a first or base coat; and (ii) a second or top coat; one pigment of said coating is of a non-smectite type; The pigment in the other coating has a water swelling of at least 60% by weight. It is said that it mainly has smectite-type properties including wet smectite-type clay. Characteristic printing paper manufacturing method. 15. The coating pigment, which is primarily smectite in nature, is present in the sheet material. 20% by weight of a pigment containing at least 60% by weight of water-swellable smectite clay. 15. Prepared by applying a water-swellable suspension comprising up to % Method. 16. The aqueous suspension contains more than 15% by weight of a pigment containing smectite clay. 16. The method of claim 15, comprising: 17. The paper on which the image is printed is made of a first material, each of which is hydrophilic, absorbent, and porous. and a second pigmented coating; The first coating is a base coat and the second coating is a topcoat. The pigments in one of these coatings are predominantly non-smectite in nature. but the pigment in the other coating contains at least 60% by weight water-swellable smek. Characterized by mainly having smectite-type properties including tight-type clay Printing images on paper using gravure, offset lithography, or printing methods Law.