JPS6197497A - Gate roll coating paper - 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] [Purpose of the invention] 0 industrial applications The present invention relates to gate roll coated paper.

More specifically, this is a particularly important property for coated paper.
No coating unevenness on the surface of the coating layer, excellent smoothness, and
This invention relates to gate roll coated paper that has excellent suitability for offset printing and gravure printing.

0 Prior Art In recent years, coated paper has rapidly become popular in the field of uncoated paper, such as lightweight coated paper and medium-density coated paper as products that respond to the trend toward higher quality magazines.

As a method for applying lightweight coating, the Gutrol method is attracting attention and being adopted by various coated paper manufacturers.

Gate roll method i1: This is a coating method using a gate roll coater in which an applicator roll is usually equipped with two or three small diameter gout rolls.

The advantages of the Gutrol method are that it is possible to apply high-concentration paint at high speed, requiring less drying energy, and that the permeation of the paint into the inside of the paper is reduced, allowing the paint to reach the surface of the paper. Since the yield of coating paper improves, the opacity increases, and as a result, the smoothness of the coated paper improves.

However, the game roll method has the disadvantage that the paint itself is subjected to a splitting action when the gate is opened, resulting in uneven coating, a phenomenon called a so-called split pattern or orange peel.

Furthermore, as a result, the coated paper has the disadvantage that its smoothness is significantly impaired and its printability is significantly reduced.

0 Problems to be Solved by the Present Invention The inventors of the present invention have conducted extensive research in view of the above-mentioned problems, and have found that when a paint with a specific structure is applied with a Gutrol coater, there is no coating unevenness, excellent smoothness, and The inventors have discovered that gate roll coated paper with excellent printability can be obtained, and have arrived at the present invention.

[Structure of the invention]

The present invention uses 1 aliphatic conjugated diolefin monomer <A) 25
~65% by weight, ethylenically unsaturated carboxylic acid monomer (B
) 0.5 to 15% by weight Other polymerizable monomers that can be bundled with the tapered fibers (C) Polymerizable monomers having a particle size of 2000 to 3000 A obtained by polymerizing 20 to 145% by weight Using polymer latex as the main binder and 0.916X
This gate roll coated paper is characterized in that it is coated with a paint having a leveling index of 02 to 16 when a shear rate of 105/sec is applied using a gate roll coater.

The leveling index referred to in the present invention is a cup with an inner diameter of 40 Mn and an effective depth of 805 mn, an appropriate amount of paint pot, a diameter of 39.8 rmn, and an effective length of 25 rrrm (
A bob with a clearance of 0.1 rmn with respect to the cup is used.

Set sweep time to 10 seconds, maximum rotation speed 4.40
Draw the hysteresis loop as 0 rpm. 2,0 read from the rising curve and descending curve at this time
The apparent viscosity difference at 0 Orpm is 4,000 r
The apparent value in pmK is divided by the viscosity and is used as the leveling index.

The leveling index of the paint in the present invention is 0.2
Outside the range of 16 to 16, coating unevenness, which is the object of the present invention, will not be improved, and neither smoothness nor printability will be improved.

The copolymer latex used in the paint of the present invention contains 25 to 65% by weight of aliphatic conjugated diolefin monomer (A) and 0.5 to 15% by weight of ethylenically unsaturated carboxylic acid monomer (B).
% by weight, other polymerizable monomers copolymerizable with these (C'
It is obtained by combining 120 to 745% by weight'i-i, and has a particle size of 2000 to 3000X.

If the particle size of the copolymer latex is outside the range of 2000 to 3000 A, coating unevenness will occur, and smoothness and printability will deteriorate.

The following monomers are used for the copolymer latex.

0 Aliphatic Conjugated Diolefin Monomer (A) Examples of the aliphatic conjugated diolefin monomer used in the present invention include 1,3-butadiene and 2-chloro-13-butadiene.

The aliphatic conjugated diolefin monomer is used in an amount of 25 to 65% by weight, but if the amount is less than 25i, the adhesive strength decreases,
If the weight ratio exceeds 65, the water resistance strength decreases.

These monomers mentioned above can be used alone or in combination of two or more.

Ethylenically unsaturated carboxylic acid monomer (B) Examples of the ethylenically unsaturated carboxylic acid monomer used in the present invention include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and itaconic acid.

The ethylenically unsaturated carboxylic acid monomer is used in a weight ratio of 05 to 15%, but if it is less than 0.5% by weight, the adhesive strength and mechanical stability of the latex will decrease, and if it exceeds 15% by weight, the viscosity of the latex will decrease. It becomes too high and difficult to handle.

These monomers may be used alone or in combination.

0' Other polymerizable monomers that can be copolymerized (C) In the present invention, other polymerizable monomers that can be copolymerized with the above-mentioned monomers include aromatic vinyl monomers, cyanide monomers, Vinyl monomers, ethylenically unsaturated carboxylic acid alkyl esters, and monomers having hydroxyalkyl groups are used.

These monomers are used in weight ratios of 20 to 745, but 2
When the amount is less than 0i, the water resistance strength decreases, and when it exceeds 74.5% by weight, the adhesive strength decreases.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyltoluene, and civinylhenzene.

The aromatic vinyl monomer can be used in an amount of 745% by weight, but if it exceeds 745% by weight, the elasticity will be insufficient, resulting in a decrease in adhesive strength.

Examples of vinyl cyanide monomers include acrylonitrile,
α-Chloracrylonitrile, methacrylonitrile,
Examples include α-ethyl acrylonitrile.

The vinyl cyanide monomer can be used in an amount of 30% by weight or less, but if it exceeds 30% by weight, printability decreases.

Examples of the ethylenically unsaturated carboxylic acid alkyl ester include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, and those having an alkyl group having 1 to 8 carbon atoms are preferred. Alkyl ester is 35i
Although it can be used in an amount below 35N, the water resistance strength decreases when the amount exceeds 35N.

Examples of monomers having a hydroxyalkyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, hydroxybutyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate.

The monomer having a hydroxyalkyl group is used in an amount of 6% by weight or less, but if the amount exceeds 6% by weight, the water resistance strength decreases.

These polymerizable monomers mentioned above can be used alone or in combination of two or more.

01 Polymerization As a method for obtaining the copolymer latex used in the present invention, a generally known emulsion polymerization method can be mentioned.

During polymerization, generally known emulsifiers, polymerization initiators,
A chain transfer agent, etc. can be used.0 Note that there is no limit to the percentage of the addition method of various components in emulsion polymerization, and any of the initial batch addition method, divided addition method, and continuous addition method may be used. A known two-stage polymerization method or multi-stage polymerization method can also be used.

Preparation of paint In the paint of the present invention, generally known pigments, natural binders, dispersants, thickeners, etc. can be used.

Pigments include clay, calcium carbonate, titanium oxide,
Examples include satin white.

Examples of natural binders include starch and casein.

Examples of the dispersant include sodium polyacrylate and sodium hexametaphosphate.

Examples of the thickener include carboxymethyl cellulose, hydroxyethyl cellulose, etc. Sodium hydroxide, ammonium hydroxide, etc. may also be used as necessary.

The leveling index of the paint can be adjusted by the solid content of the paint, the amount of thickener, etc.

The present invention will be specifically explained below using Examples, but the present invention is not limited by these in any way.

In addition, parts in this example mean parts by weight. Example 1 Nine types of latex shown in Table 1 were created.

Except for Latex 4, a mixture of each monomer shown in Table 1, 08 parts of sodium alkylbenzenesulfonate and sodium bicarbonate, 08 parts of ammonium persulfate, 05 parts of tertiary dodecyl mercaptan, and 100 parts of water was charged into an i10/autoclave, and while stirring. Polymerized. Polymerization temperature is 6
It was carried out at 5°C.

The polymerization conversion rates of the obtained latexes were all 99% or higher.

Latex 4 was subjected to two-stage polymerization.

That is, each monomer shown in parentheses in Table 1 was additionally added when the conversion rate in the first stage reached 80%, and the polymerization was completed. The final polymerization conversion rate was 99% or more.

After removing unreacted monomers from these latexes by stripping them, latexes 1 to 9 were obtained by passing them through a 200 mesh wire gauze.

Example 2 A paint was created using the following recipe.

Kaolin 8
0 (parts) Heavy calcium carbonate 20 Oxidized starch 10 Latex
20 Caustic soda 03 Polyacrylic acid powder 03 Solid content (%) 55 Diameter 150 pieces) was used to make medium base paper (weighing 55 y/77
+') Fell i/surface VC7, ->/ltX coating amount V
I coated it to make it look like C. The coating speed was 200 m/m1, and the peripheral speed ratio of each roll was applicator: inner roll: outer roll -1: O, s; 0.5.

The evaluation results of the fluidity and paper quality of each paint are shown in Table 2.\\ "Smoothness" Measured using a Nibeck smoothness tester (manufactured by Kumagai Riki Kogyo). The ventilation time of 10 cc was determined.

The larger the number, the better the smoothness.

"Gravure suitability" was measured using a Ministry of Finance model gravure printing tester (manufactured by Kumagai Riki Kogyo). The misdot occurrence rate of the 15% dot printed area was determined.

The smaller the value, the better the smoothness.

"Coating unevenness": The coated paper was heat treated in the open (220°C) for 3 hours to carbonize the cellulose.

The state of the remaining coat layer was determined.

[Adhesive strength J: Using an RI printing machine (Mei Seisakusho), the picking state of the coated paper was visually judged after printing four times with offset ink (tack value: 16). Evaluation was made on a three-level scale: ○ (excellent), △, and × (poor).

"Water Resistance Strength J: An RI printing machine was used. Using a water-containing Molton roll, the coated paper was wet and printed with offset ink (tack value: 12), and the picking state of the coated paper was checked with the naked eye. Similarly, evaluation was made using a 3-step scale from ○ to ×.

Example 3 Paint f! created in Example 2! 4, and high-quality base paper (53
9! / rrj ) felt surface VC5, Of! /
Coating of m' was carried out using the following ratio: eplicator roll: inner roll: outer roll -1, o: 0.7: 0.7.

The evaluation results are shown in Table-3.

Example 4 30 y of caustic soda (20% solution) and 15 y of sodium polyacrylate (40% solution) were added to 1257 PK of water, and each pigment shown in Table 4 was added so that it was 3000 p i/i': A pigment slurry was prepared using a Coles type dispersing machine.The starch and latex shown in Table 4 were added in the same manner, and finally water was added to prepare paints A to ■.

A coated paper was prepared in the same manner as in Example 2.

The evaluation results are shown in Table-5.

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Claims (1)

[Claims] 1. Aliphatic conjugated diolefin monomer (A) 25-65
Weight %, ethylenically unsaturated carboxylic acid monomer (A) 0.
Mainly a copolymer latex with a particle size of 2000 to 3000 Å obtained by polymerizing 5 to 15% by weight and 20 to 74.5% by weight of other polymerizable monomer (C) copolymerizable with these. A gate roll coated with a paint used as a binder and having a leveling index of 0.2 to 1.6 when applied with a shear rate of 0.916 x 10^5/sec using a gate roll coater. Coated paper.