KR20040066905A - 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.

Description

COATED PAPER WITH SILKY FEEL}

Different compositions are coated on different species 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 devices and subsequent calendaring devices.

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.

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.

Applicants of the French patent are designed to provide a feature reminiscent of the use of the product, mainly 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 chalking and setting-off that occur during offset printing.

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

This choking phenomenon results in poor blending of the binder and the dye (ink), i.e. an excessively high amount of dye to 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 at the time of lamination.

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 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.

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

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.

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 fertilizer, 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 70-500 g / m ² , preferably of 100-300 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 present invention is characterized in that it is a tracing paper obtained by tapping on constituting cellulose fibers in particular.

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

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

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

Examples 1-5

As shown in Table 1, a composition comprising polyurethane microbeads of various sizes 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. Apply at the rate of 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 6-13

7 per side on a sheet of base paper having a micrometer to the air of a composition comprising a polyurethane microbeads having an average size using a blade coater on the weight of 100g / m ^2, available as Conqueror CX22 from the applicant company of 5g / m ² The ratio of the binder is varied with respect to the weight of the dye as shown 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.

The aqueous polyurethane emulsion Rolflex PAD is variable in the dried state.

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) Apply to at least one piece of paper coated with the composition as follows on 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; .

b) A single pass process is performed on the 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 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 in the printing section is set to 1000N, and the pressure in the transfer section is set to 400N.

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

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

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 of less than 10 micrometers in size could obtain acceptable silky touch.

As a result of the test of Examples 6 to 13, it was found that the silk touch required according to the selection of the microbead size can be obtained. It has proven to be preferable to include the following binders.

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 sold by Lamberti

-6.1kg, Daiplacoat RHU 5070 Polyurethane Micro Beads marketed by Promecome

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

-The above ratio is 5.4g / m ² of dry weight per side, and the amount 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 exhibited silk touch on both sides.

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

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 at all during offset printing.

Claims (7)

A coating composition for coated paper to be offset printed, including a dye and a binder, wherein the coating dye comprises polyoleethane microbeads having a size of less than 10 micrometers, preferably 7 micrometers. Coating composition. The coating composition of claim 1 wherein the binder used has an aqueous emulsion of polyurethane, elongation of at least 500%. The coating composition according to claim 2, wherein the binder is contained in a weight ratio of 40% or more, preferably 200% or more. A paper having a silk feel coated on at least one side with the coating composition claimed in any one of the preceding claims. 5. The silk tactile feel according to 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 NF-Q-03-082 is 1.0 or less. Having a paper. Claim 4 or according to 5, wherein the coating weight is at least coated on one surface 2 on a dry weight - paper having a silky feel, characterized in that ^{6g / m 2 - 10 g /} m 2, preferably 3. 7. Paper according to any one of claims 4 to 6, which is a tracing paper made of the cellulose fibers and obtained by tapping.