SE468531B - SHEET COPY PAPERS - Google Patents

Abstract

The present invention provides a copying paper which both has good printability and which can be run satisfactory in sheet copying machines. The invention relates to copying paper which inlcudes a base paper based on a fibre starting material of which at least 60% is comprised of short fibre pulp refined to 17-22 DEG SR and at least 20% long fibre pulp refined to 25-38 DEG SR, and filler in an amount of 19-28%, calculated on the base paper. At least one side of the base paper is coated to a surface weight of 12-18 g/m<2>. The copying paper is characterized in that the base component(s) of the coating layer includes/include either a) 100 parts of calcium carbonate distributed according to 60-80 parts of calcium carbonate of which 90% have a particle size beneath 2 mu , and 40-20 parts of calcium carbonate of which 95% have a particle size beneath 2 mu ; or b) 60-90 parts of calcium carbonate of which 90% have a particle size beneath 2 mu , and 40-10 parts of kaolin clay of SPC (selected particle size) quality; and in that the surface coating also includes at least binder and hardener.

Description

10 15 20 25 30 1í68 531 toppings are clearly distinguished -from pigment coating. With the the latter refers to the use of, for example, calcium carbonate. clay. with several pigments individually or in combination with each other in relatively large quantities.

On the market today are available in the form of rolls of paper, of standard offset quality, for combined printing and copying.

However, the use of this paper is limited to such copying machines, such as laser printers. for roll use. which are built All sheet-fed copying machines stand outside that handling. It has been shown that if printed paper in roll form is converted to sheet form for use in sheet-fed copiers is not achieved well driveability 1 the copier, ie. it will be time after another stop in the machine.

Conventional copy paper has the disadvantage that previously stated that a high-quality print cannot be held.

Disclosure of the Invention Technical problem It has proved difficult that in one and the same copy sheet paper in combination form good printability and good 1 copiers, such as laser printers. One of the problems are. that fully coated paper does not allow fed into the copier in a good way. which leads to repeated stops. This with the friction of the paper to do. Another problem is, that said paper often does not retain its original planar shape during copying which also leads to repeated stops. can have Solution The present invention is a solution to the above problems and refers to copy paper containing base paper based on fiber raw material of at least 60% to 17-22 ° SR ground short- fiber pulp and of 'at least 20% to 25-38 ° SR ground long fiber pulp and fillers in an amount of 19-28%, calculated on 10 15 20 25 30 35 1168 531. the base paper, and on at least one side of the base paper a coating layer with a basis weight of 12-18 g / m2, characterized from the fact that the coating layer as base component (s) holds either a) 100 parts of calcium carbonate distributed according to 60-80 parts calcium carbonate where 90% has a particle size below rising 2 / b and 40-20 parts of calcium carbonate where 95% have a particle size below% ¿y or b) 60-90 parts of calcium carbonate where 90% have a particle size less than 2 / u »and 40-10 parts of kaolin clay SPC (selected particle size) quality and that the coating layer further contains at least binders and hardeners.

The binder preferably consists of starch and / or latex. It is especially preferred that the starch be oxidized and that the latex is of the open styrene butadiene type. Appropriate batch amount of starch is 5-7%, calculated on dry pigment or base component (s). Suitable additive amount of latex is 6-8%, based on dry pigment or base component (s). This applies when adding both of these chemicals to the coating and later the paper. If either of these chemicals It is in- potassium is used, the amount of additive must be increased. that the hardener is free of formalin. For example, is glyoxal useful in. an amount of 0.5 -1.5% calculated on dry pigment or base component (s). Other useful hardeners are ammonium zirconium carbonate, ethanedial, which is a polymer with tetrahydro-4-hydroxy-5-methyl-2- (1H) pyrimidinone and as is propoxylated and a hardener with the trade name Nopcote 1670, as an imidazoline compound, which is a reaction product of glyoxal and urea.

According to a. embodiment of the invention contains the coating layer and thereby the paper 1-3 parts of stearate, preferably calcium or ammonium stearate, based on 100 parts basic component (s).

The dry matter content 1 of the coating batter and thereby also in the coating layer in a pinched condition must be within range 65-70%. contains one 10 15 20 25 30 468 531 It is absolutely preferable. that the copy paper shows a coating layer on both its sides.

The filler included in the copy paper can consists of any known filler. However, is calcium carbonate preferred.

As for the printing on the copy paper, it happens usually before copying. Said printing can either take place on paper already converted to sheets or on paper, which is 1 roll shape. In the latter case, the paper must be converted to sheets before the copy step.

Coating pads of the type described above give 1 first hand a matte paper, ie. a paper that has a gloss like less than 20% measured according to Lehman (70 degree incidence) light).

It is possible within the scope of the invention to produce even glossy papers. In that case, the coating the composition of the batter slightly from the composition which gives a optimally matte copy paper and an extra may be required chemical additive.

Benefits Copy paper according to the invention shows both good printability as good driveability 1 copiers. Through to choose the right base paper and the right composition of coatings it has proved possible to achieve the same reliability 1 copier for preprinted copy paper which, in the case of conventional copying paper. The stop frequency in small at the finding. the finding good the copier is outermost use of the copy paper according to Of course, according to the driveability 1 copiers also as unprinted paper. Furthermore, they are included in the coating layer the chemicals are comparatively cheap overall, which means bears, that the price of the copy paper can be kept comparatively low. 10 15 20 25 30 Best embodiment The copy paper according to the invention is described below in more detail and the section concludes with an example. As for the base paper fiber composition so the one previously stated to be at least 60% shall consist of short fiber pulp and at least 20% consist of long fiber pulp.

By short fiber pulp is meant chemical pulp. preferably sulphate made of, for example, hardwood, such as birch, eucalyptus, beech, tree species. With long fiber pulp refers to chemical pulp, preferably sulphate pulp, made from pulp, asp et al. for example softwood, such as pine, spruce and others. tree species. One Another useful chemical pulp is sulfite pulp.

The remaining 20% of the fiber composition can be constituted of either of the two types of pulp mentioned or a mixture hence. It is also quite possible to mix other types of lots of sulphite pulp and / or high yield pulp, for example mechanical mass. The fiber composition of the base paper, the grinding of the different masses and the filler of the paper content must be adjusted so that the finished paper shows low curl tendency (reactivity). By curl is meant, that the paper deviates from the flat shape and assumes varying degrees curved shapes.

Consistently applies, should be ground only moderately, ie. at the same time as the above is fulfilled shall other grinding-dependent properties are imparted to the paper in as that the masses as far as possible. The different masses are ground separately to before specified degree degrees specified in ° SR, ie degrees Schopper- Riegler.

The amount of filler should amount to 19-28%, approximately 20-25%, calculated on the base paper. Preferred filling means are calcium carbonate in various forms. such as chalk, ground marble and precipitated calcium carbonate. However, it is possible to use in full or in part also other fillers, such as kaolin clay, talc and gypsum (CaSO4). before- 10 15 20 25 30 468 551 The structure and production of the base paper has significant importance for the drivability of the finished paper in copiers. The composition of the coating layer has large and in some cases crucial to the finished product paper driveability in copiers. The amount of toppings also affects to some extent.

The coating layer (s) of the copy paper according to the invention comes from either of two coatings.

One batter contains as a pigment or base component 100 parts calcium carbonate. Calcium carbonate is included different particle size distribution and the calcium carbonate are given have different degrees of fineness, such as fine, super fine, etc. In this cases 60-80 parts of such calcium carbonate were used, where 90% of the particles have a size less than Qyp, and 40-20 parts of an even finer calcium carbonate, namely where 95% of the particles have a size less than 2 / Q. In addition to those the aforesaid ingredients in the form of binders and harder, the batter can be added optical brightener, tinting color of various kinds and a substance for adjusting the pH in smeten. Examples of such substances are sodium hydroxide and ammonium niak. The additive amounts of binder and harder have previously specified. As for the amount of additives of the others chemicals, it is at a very low level, ie. l del or less. Additional chemicals can also be added smeten.

The second batter contains as pigment or base composition 60-90 parts of calcium carbonate where 90% of the particles has a size less than Q; toch 40-10 parts kaolin clay of SPS quality. SPS is an abbreviation of the English the name "selected particle size". This batter also contains holds binders and hardeners in the previously stated amount.

The batter can also contain optical brightener, tint color and an alkali for adjusting the pH level m.m. It is drawn, that the batter also contains a comparatively large 10 15 20 25 30 468 531 amount of stearate. Said additive has been found to provide paper paper very good runnability in copiers.

The stearate probably helps to give the paper the right surface unity and above all the right friction.

It is possible to add stearate even in the first smeten.

With regard to these two coatings, it can be mentioned that starch is normally avoided as a binder at peak coatings, as the starch provides a strong binder hiking, with a flaming pressure (mottling) as a result. One advantage of the starch additive is that the paper is imparted well stiffness and good toner adhesion and further prevents it sticking in copiers, when the paper is exposed high temperatures. Furthermore, the addition of stearate in early quantity not previously used in the coating context.

According to a preferred embodiment of the invention this is the case both sides of the copy paper are provided with a coating layer. The coating in that case is carried out in a two- stations coating machine.d As previously stated shall the coating batter have a comparatively high dry content, namely within the range of 65-70%. After the paper is ironed, the same is dried first on the first coated side and then on the other side. The drying of the first the side is operated so that the paper contains 6-9% water and the drying of the other side is continued until the paper water content is 4-5%.

An embodiment of and the properties of copy paper in accordance with the finding in comparison with the production of and properties of copying paper outside the invention.

Example 1 A base paper was prepared on a 6.5 m wide paper machine of the type Valmet in the following way. 10 15 20 25 30 468 551 Three types of pulp fibers were mixed in the following amounts.

Sulphate pulp of birch = 70%. Pulp sulphate mass = 24%.

Sulphite pulp of spruce = 6%. Before mixing, grind separately the three masses to the following degrees of grinding: Birch mass = 18 ° SR. pine mass = 34 ° SR and spruce mass = 18 ° SR.

Fillers, mainly calcium carbonate, were added 1 an amount of 2l.2% in finished paper. 131 kg filler was added per tonne of paper as dispersion and the remainder fillers were added via incoming committee paper.

Hälden also contained the following chemicals: Starch (cationic active) = 4.5 kg / ton of paper Glue (alkyd chain dimer) = 8.5 "' Retention aid 1 (polyacrylamide) = 1.7 "“ Retention aid 2 (bentonite clay) = 0.16 " Optical brightener (ßlankophor P) = 0.4 ”“ Tint color (ethyl violet) = 0.02 '“ The paper was surface glued with an 8% surface glue starch in a spread of about 3 g / m.

The base paper described above with a basis weight of 97 g / m2 was applied coating batter A. B and C. Coating batter A was applied the base paper both in a pilot coater and 1. a full-scale experiment, while the coating blanks B and C were applied to the base paper only 1 pilot coater. The three coaters had the following compositions.

A 80 parts of calcium carbonate under the trade name Hydrocarb 90 in one 75% dispersion. 90% calcium carbonate has one particle size less than 2 / ¿. 20 parts SPS coating clay (kaolin), which is dispersed with 0.2 parts of polyacrylate to a dry matter content of 68%.

These two pigments or base components were mixed together. Where- after was added: of this f) 10 15 20 Iæ 30 468 551 6 parts styrene butadiene latex with the trade name Dow 905 and 6 parts oxidized starch with the trade name Cerestar Boiled to a dry content of about 32%.

Then it was added in the following order: 0.8 parts hardener (glyoxal), 2 parts calcium stearate with the trade name Nopcoat C104, 0.8 parts optical brightener under the trade name Blankophor PC 0.001 parts shade color (levanyl violet).

Ammonia was added. so that the pH of the batter became 8.5 and its dryness content was 65%.

B 80 parts of calcium carbonate under the trade name Hydrocarb 90 1 en 75% dispersion. 90% of this calcium carbonate has a par- article size less than 2 / L. 20 parts of calcium carbonate under the trade name Setacarb in a 75% -lg dispersion. 95% of this calcium carbonate has a particle size which is less than 2 / ¿.

These two pigments or base components were mixed together. Where- after was added:, 6 parts styrene butadiene latex with the trade name Dow 905 and 6 parts oxidized starch with the trade name Cerestar 05595, cooked to a dry content of about 32%.

Then it was added in the following order: 0.8 parts harder (glyoxal) 0.8 parts optical weight with the trade name Blankophor PC. 0.001 parts shade color (levanyl violet).

Ammonia was added so that the pH of the batter became 8.5 and its dry matter content was 68%.

Q 100 parts SPC coating clay (kaolin) dispersed with 0.2 parts of polyacrylate to a dry content of 65%.

To the clay was added: 10 15 20 25 30 10 468 551 6 parts styrene butadiene latex with the trade name Dow 905 and 6 parts oxidized starch with the trade name 05595, cooked to a dry content of about 32%.

Then it was added in the following order: 0.8 parts harder (glyoxal) 0.8 parts optical brightener under the trade name Blankophor PC. 0.001 parts shade color (levanyl violet).

Cerestar Ammonia was added so that the pH of the batter became 8.5 and its dry matter content was 59%.

The coatings were performed under realistic conditions, partly on a pilot coater (batter A. B and C) with curved blade at a speed of 800 m / minute and partly on full-size coaters (batter A) with a width of 3.3 meters of type Jagenberg with height blade at a speed of 800 m / minute. In all cases, the basic the paper is coated on both sides in an amount of 16 g / m2. The basis weight of the finished, coated paper was 130 g / m2.

All papers were carpet according to the previously stated definition.

As for paper driveability in copiers, it has proved that in order to obtain good driveability, it should the friction of different materials be as follows.

The friction between the feed belt and the paper should be greater than the friction between the brake band and the paper, which 1 in turn must be greater than the friction between paper and paper paper.

The friction between the different materials including the four the papers have been measured according to ASTM (American Society for Testing and Materials) Dl894.

The measurement of the friction has been made so that in one case measured the friction between the feed belt and the top of the paper (OS) and in the second case between the feed belt and the paper virasida (US). Measurements have been made in a similar way with regard to the braking belt and the paper. The papers have both static as kinetic friction is measured. The results are shown in 'below- standing table l. 10 15 20 25 30 ll Tdælll Friction in spruce Try Batter Feeding Belt / Paper 'Braking Belt / Paper Paper / Paper island vs island vs static kinetic Full scale A - 292 262 260 257 ll0 80 Pilot A 232 235 170 162 83 60 Pilot B 440 372 258 255 122 94 Pilot C 505 468 l43 200 66 65 Other experiments have shown that the mixture of only clay as pigment or excessive amount of clay in the coating if the runnability of the paper 1 of all copiers is negative, as is the case with the Pilot C paper. closing the stearate additive in the papers according to Full Scale A and Pilot A, that the runnability of the paper deteriorates in all copiers.

It has been shown that the difference between static and Chinese The friction of the paper reflects the runnability of the paper 1 copiers. Double feeding of paper and other phenomena, which stops the copiers has been shown to increase with reduced difference in static and kinetic friction of the paper.

From Table 1, the mentioned numerical values and the difference are repeated between the numerical values is shown in Table 2 below.

Table 2 Friction in grams Try Batter Static / Kinetic Difference Full scale A 110/80 30 Pilot A 83/60 23 Pilot B 122/94 28 Pilot C 66/65 1 In the tables above, the first three papers are in accordance with the invention, which is not the case with the fourth paper, i.e. what has been applied to the coating batter C. The difference, between static and kinetic friction of the papers according to the invention 10 15 20 12 _P- Ch OO UI (N _.) is 23 or more, while the corresponding difference of the paper for the invention (0-sample) is so small. as 1. In order to copy the ring paper must have full function and driveability set the requirement, that 5000 copies (simplex) and 3000 copies respectively (duplex) must be able to be copied in a sequence, without it becoming any stop in the copier. By simplex is meant that one copies only on one side of the paper and by duplex is meant, that you copy on both sides of the paper.

Experiments with all four papers were performed on four copiers. Rank Xerox type machines with the designations 4050, 4090. 5090 and 9700. As for the three papers according to the invention so no stop was obtained within 5000 copies in either simplex or duplex, while the paper outside the invention, i.e. The 0-test, led to more than one stop within 1000 copies at both simplex and duplex.

These experiments show. that the contents of the paper coating layer or if you so wish the structure of the coating layer has crucial for the behavior of the paper when feeding in the copier and during the copy process. In this case the 0-test has also been performed with a base paper. which is in accordance with the invention. If the coating batter C has been applied to a base paper otherwise had the difference in runnability in the copier between the papers has been even clearer.

Claims (1)

10 15 20 25 30 13 ß C | \ CO C fl LN ... x PATENTKRAV. Copying paper containing base paper based on fibrous raw material of at least 60% to 17-22 ° SR ground short fiber pulp and of at least 20% to 25-38 ° SR ground long fiber pulp and fillers in an amount of 19-28%. calculated on the base paper, and on at least one side of the base paper a coating layer with a basis weight of 12-18 g / m2, characterized in that the coating layer as base component (s) contains either a) 100 parts of calcium carbonate distributed according to 60-80 parts calcium carbonate where 90% has a particle size of less than 2 / L and 40-20 parts of calcium carbonate where 95% has a particle size below eggs or b) 60-90 parts of calcium carbonate where 90% has a particle size of less than% / u / and 40-10 parts of kaolin clay of SPS (selected particle size) quality and that the coating layer also contains at least binder and harder. Copying paper according to claim 1, characterized in that the binder consists of starch and / or latex. Copying paper according to claim 2, characterized in that the starch is oxidized and that the latex is of the open styrene butadiene type. Copy paper according to claim 1; k ä n n e t e c k n a t there is a reason why the hardener is free of formalin. Copying paper according to claims 1-4, characterized in that the coating layer contains 1-3 parts of stearate, preferably calcium or ammonium stearate, based on 100 parts of base component (s). Copying paper according to claims 1-5. It is known from this that the coating layer 1 newly applied condition has a dry content of 65-70%. Copy paper according to claims 1-6, characterized in that coating layers are applied to both sides of the base paper. Copying paper according to claims 1-7, characterized in that the filler consists of calcium carbonate. Copy paper according to claims 1-8. Note that the paper was converted to sheet form before copying.