KR100956864B1 - Coated paper with silky feel - Google Patents

Abstract

The present invention relates to a coating composition of coated paper printed by offset printing, wherein the coating dye comprises polyurethane microbeads having a size of less than 10 micrometers, preferably 7 micrometers.

The invention also relates to a paper having a silk feel coated on the at least one side, preferably on both sides with the coating composition.

The paper according to the invention is characterized in that it can be offset printed with virtually no troublesome properties of buried and chalking.

Coated paper

Description

COATED PAPER WITH SILKY FEEL}

The present invention relates to a coating composition comprising polyurethane microbeads and a paper coated with the coating composition on at least one side, preferably both sides.

Various compositions are coated on different types of paper to improve the quality of the paper surface.

Coating compositions commonly used for this purpose are dispersants comprising organic or inorganic dyes.

Such coating compositions may also include other additives.

Printing paper or wrapping paper, such as paper for books, magazines, brochures or year reports, is often made by coating the base paper using one or more coating units and subsequent calendaring.

The final product should generally have a surface property suitable for the application.

These surface properties are mainly reflected by changing the appearance of the paper, for example by improving the brightness, gloss or opacity, and the like.

The study of the touch on coated paper is completely new.

Conventionally, in French patent 2791368, the wrapping paper of interest to the applicant company comprises a feature that reminds of the main characteristics of the product to be packaged, in particular a cosmetic product.

The Applicant of the French patent proposes to provide a use of the product, primarily a feature reminiscent of the softness or feel of the skin.

It is desired to obtain the required sensation by applying a coating layer comprising expandable thermoplastic microparticles to the surface of the paper.

The present invention aims to solve the problem of processability which occurs during the printing of such sheets, in particular the problem of separation of laminated sheets due to the non-slip properties of added microparticles.

In general, coated thin papers cause serious problems during printing or switching operations, the most common of which is choking and setting-off that occur during offset printing.

The above mentioned choking is the separation of the coating in the form of dry powder during printing, which is more pronounced during the continuous movement of the sheet in a printing press or a converter.

This choking phenomenon results in a poor blending of the binder and the dye (ink), ie the dye has an excessively high content of the binder.

The choking phenomenon may also be caused as a result of the shape and size of the dye particles.

Buried is a phenomenon in which the ink of one paper is buried on the next printed paper, especially when laminated.

It is common to see a rather strong ink stain on the back of the paper, which is caused by the ink on the front of the paper.

When the printed paper is separated in the laminated state, the sound of paper tearing is somewhat loud.

This phenomenon is known as a buried phenomenon in the weak case.

However, when the stacked printing papers are separated, some of the papers may fall together.

Also, in severe cases, the sheets may be adhered to each other by ink during lamination, and thus the papers may not be separated from each other.

The above paper exhibits this phenomenon because the paper is inadequate for ink and the ink receiving property is weak, and because the ink requires excessive ink for accurate printing on a paper having an uneven surface.

In this regard, the applicant has sought to develop a paper having a silky feel, which is coated on both sides and does not cause the problems of printability and processability stated above.

It is an object of the present invention to provide a coating composition for coated printing paper, characterized in that the dye used in the coating composition consists of polyurethane microbeads having an average particle size of less than 10 micrometers, preferably 7 micrometers. will be.

In particular, the invention is characterized in that the binder used in the coating is a polyurethane, preferably a soft polyurethane polyurethane aqueous emulsion having a loss rate of at least 500%.

In particular, the present invention is characterized in that the binder is at least 40% by dry weight, and preferably at least 200% by dry weight relative to the dye.

It is another object of the present invention to provide a silk tactile coated paper, wherein the coating composition is coated on at least one side, preferably on both sides.

The coated paper is characterized in that it can be offset printed so low as to be virtually free of smudging and choking.

The paper is based on cellulose fibers and preferably has a weight of 70 to 500 g / m ² , preferably of 100 to 300 g / m ² .

In special cases, the paper may be transparent or translucent.

In particular, the paper may be made of tracing paper.

By "tracing paper" above is meant a paper as defined in the international standard ISO 4046-1978, 6.94.

In particular, the invention is characterized in that it is a tracing paper obtained by especially hard beating the constituting cellulose fibers.

In particular, in the present invention, it is preferable that the weight of the coating layer applied to at least one surface is 2 to 10 g / m ² , preferably 3 to 6 g / m ² in a dry state.

The paper has a dynamic friction coefficient of 1.0 or less on the coated front side and the coated back side, the friction coefficient being measured according to the French standard NF-Q-03-082 with a block of 200 g weight.

The dynamic coefficient of friction affects the static characteristics when the paper is about to move, and the larger the coefficient of dynamic friction, the more difficult the paper is to move in the laminated state.

The present invention will be described in more detail with reference to the following comparative examples and non-limiting examples of the present invention.

1 is a 200-fold enlarged planar photograph of a silky paper according to the present invention,

Figure 2 is a 2000 times magnified cross-sectional micrograph of the silk tactile paper of the present invention.

Examples 1 to 5

As shown in Table 1, a composition comprising polyurethane microbeads of various sizes was applied per sheet to a sheet of base paper having a weight of 100 g / m ² sold by the Applicant Company as Conqueror CX22 using an air blade coater. Apply at a rate of g / m ² .

Compositions comprising polyurethane microbeads are prepared in an aqueous medium and have the following compositional ratios in dry weight ratio.

24.7 parts of water

0.1 part wetting agent

33.3 parts aqueous polyurethane emulsion Witcobond 290 H

-20 parts polyurethane microbeads

0.5 part pH adjuster

-1 part thickener

Examples 6 to 13

A composition comprising polyurethane microbeads with an average size of 7 micrometers was applied to a sheet of base paper having a weight of 100 g / m ² sold by the Applicant Company as Conqueror CX22 using an air blade coater at 5 g / per face. The ratio is applied in m ² , and the concentration of the binder is changed with respect to the weight of the dye as described in Table 2.

The composition comprising the polyurethane microbeads is prepared in an aqueous medium and has the following composition ratio in dry weight ratio.

-Aqueous polyurethane emulsion Rolflex PAD in variable parts during drying

-20 parts polyurethane microbead Daipleacoa RHU 5070

0.5 part pH adjuster

-1 part thickener

exam

-The hand feel of the paper surface containing the coating of the polyurethane microbeads is evaluated by hand.

The original results for the choking test show a tendency for the coating to separate as the paper passes through the machine. Such choking test is performed as follows.

a) at least one piece of paper coated with the composition as described below in a block covered with black felt made of (70% wool, 30% polyamide) fibers having a size of 40 mm x 40 mm and a weight of 2 kg; Apply with

b) A single pass process is carried out on paper in a single overall length of 6 m.

c) Remove the felt from the block.

d) the effect of felt is measured using an Elrepho device (measured to 1.4 compared to that of untreated fibers)

-The results of the test for the buried tendency of the coating to stick to the back sheet in printed paper indicate the buried tendency of the coating during mechanical lamination of the coated paper. Buried tests of such coatings are performed in the following manner.

a) Prepare a paper specimen to be tested with a width of 48 mm and a length of 250 mm.

b) Test using a Prufbau tester with a print section of the first station and a transfer section of the second station.

c) The pressure at the printing section is set to 1000 N, and the pressure at the transfer section is set to 400 N.

d) The feed rate of the tester is set to 0.5 m / sec.

e) The ink roller of the printing unit is in contact with the ink for 30 seconds with Huber 408010 type blue ink.

f) Place the conveyor with the specimen in front of the printing section.

g) A roller without applying ink is disposed in the transfer portion.

h) Print the specimen on the printing section.

i) The stopwatch starts working with printing start.

j) The test piece of the same paper is arrange | positioned to the empty roller of a transfer part using an adhesive tape.

k) When the stopwatch passes 120 seconds, the conveyor with the printed specimen is stopped under the empty roller.

l) Immediately remove the specimen from the transfer section from the roller.

m) The light density of cyan transferred to the blank specimen is measured using an Xrite density meter.

Test result

The test results in Examples 1 to 5 are shown in Table 1.

Although most of the test papers showed satisfactory results in the buried test and choking tests of the coatings, it was found that only microbeads less than 10 microns in size could obtain an acceptable silky feel.

As a result of the test of Examples 6 to 13, it was found that the silk feel required according to the selection of the microbead size can be obtained, and 40% or more of binder is selected by weight to prevent choking, and 200% by weight to prevent burping It has been found that it is preferable to include the above binder.

This is because the choking is satisfactory at 2 or less and the buried is satisfactory at 0.1 or less.

1 and 2 are electron micrographs of the paper of the present invention of silk feel from the applicant's point of view.

This paper is obtained by applying the following coating composition on both sides to a Conqueror CX 22 base paper having a weight of 100 g / m ² .

-2.8 kg of water

-0.03 kg of Texapon Z95P wetting agent

-81 kg Rolflex PAD binder marketed by Lamberti

-Daiplacoat RHU 5070 Polyurethane Microbead, marketed by 6.1 kg of Promecome

CMC Blanose 7M65, marketed by 1 kg of Aqualon, 2.5% thickener

-The above ratio is 5.4 g / m ² of dry weight per side, the amount of which is determined in consideration of commercial viability.

The paper obtained is subsequently subjected to a calendaring process.

1 and 2 are 200 times photographs and 2000 times enlarged cross-sectional photographs of the plane for each.

The paper obtained as described above showed silk feel on both sides.

 The dynamic coefficient of friction for the coated paper, measured in 200 g blocks according to the French standard NF-Q-03-082, yielded a value of 0.8, which ensures good processing characteristics on printing and transfer machines. do.

TABLE 1

Particle Name Daiplacoat Decolam F7 Decolam FT Decolam f Decolam w Particle size (micrometers) 7 10 28 28 50 Silk touch Yes Acceptable middle middle no Chalking 1.8 1.6 1.6 1.6 1.6 Setting-off 0.4 0.32 0.42 0.39 0.2

TABLE 2

Dye binder% level 10% 20% 30% 40% 50% 100% 150% 400% Silk touch Yes Yes Yes Yes Yes Yes Yes Yes Choking 15.5 6 3.6 1.9 1.7 1.5 1.5 1.5 Burial 0.282 0.326 0.327 0.354 0.367 0.123 0.104 0.07

According to the present invention, a coating of a composition containing thermoplastic microparticles is obtained, thereby obtaining a silk-touch paper in which no chalking and smearing occurs during offset printing.

Claims (10)

In a coating composition for coated paper to be offset comprising a coating dye and a binder, the coating dye is a polyurethane microbead having a size of 7 to 10 micrometers, the binder is an aqueous emulsion of polyurethane, and The binder is a coating composition, characterized in that 40% to 400% by weight relative to the dye. delete delete A paper having a silk feel coated on at least one side with a coating composition as claimed in claim 1. The method of claim 4, wherein the coefficient of dynamic friction between the front side of the coated paper and the back side of the coated paper is a 200 g weight block, wherein the measured value according to the French standard NF-Q-03-082 is 0.8. Paper with a silky touch. The paper having a silk feel according to claim 4, wherein the weight of the coating applied to at least one side is 2 to 10 g / m ² as dry weight. The paper having a silk feel according to claim 4, which is a tracing paper. 5. Paper having a silky touch according to claim 4, wherein both sides are coated. 7. The paper having a silk feel according to claim 6, wherein the weight of the coating applied on at least one side is 3 to 6 g / m ² as dry weight. 8. The paper having a silk feel according to claim 7, wherein the tracing paper is obtained by tapping cellulose fibers constituting the tracing paper.

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