DE2700657A1 - COATING MATERIAL - Google Patents

Description

Coating

J · v.'l - j -j.

.1.

The invention relates to a coating slip consisting of a Binder dissolved or divided in water or a mixture of binders and pigments, which are applied to the surface of paper and cardboard is applied to improve its surface properties. In particular, papers are coated in order to make them easier to print, such papers are, for example under the name of art paper, chromo paper and chromo cardboard known.

Commonly used coating pigments are blanc fixe (barium sulfate), kaolin or satin white (calcium sulfoaluminate). Known binders include proteins such as casein, gelatine, soy protein and also yeast protein after appropriate pretreatment. The latter, in particular, is initially unsuitable as a binder in its natural globular structure and must first be subjected to an alkali treatment to break down its globular structure, resulting in elongated and sometimes shortened molecules which then have binder properties. (J. Ferment. Technol. ^ (1974) 6, p. 399 407). The direct use of alkali decomposition products of yeast as binders is also known. However, in order to avoid disadvantages for the whiteness of the papers, these products have to be decolorized by the action of a peroxide or reducing agent in addition to the alkali treatment (BRD-AS 2 303 656). Proteins and the starch, which is also used as a binding agent, are also used for human nutrition. This results in the further disadvantage that the technical application deprives essential means for solving the nutritional problem.
The result is a constant shortage of proteins and starch.

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Efforts are therefore being made to use plastic dispersions instead like ζ. B. polyacrylate or acrylic, vinyl and styrene copolymers to use·

However, these agents have a lower water retention capacity and thus cause increased binder migration into the carrier material when the coating material is applied. This leads to a reduced coating quality, in particular with regard to the coating strength. As a result, when these surface-finished papers are processed by printing technology, the line can be lifted, known as "plucking". This disadvantage can usually only be caused by a higher proportion of binder in the
Coating mass are balanced

The object of the invention is now to provide a paper coating slip, which lead to the desired properties of a high-quality, surface-refined paper with a low level of binder, but at the same time offers the possibility for To completely or partially replace proteins that are more sensible to use for food purposes.

According to the invention, this object is achieved with a paper coating slip which, as a binder, contains a mixture of nucleic acids and / or their derivatives, e.g. salts in the form of nucleic acids and nucleotides alone or with proteins and / or carbohydrates, possibly in combination with other common binders In a preferred embodiment, the binder, based on the total dry mass of the binder component, consists of
up to 90% by weight nucleic acid and / or sodium nucleinate
and / or nucleotide, up to 30% by weight from protein and up to 15% by weight from carbohydrates. Another preferred embodiment provides a composition as a binder
containing up to 90% by weight of nucleic acid and / or sodium nucleinate

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and / or eucleotide, up to 30% by weight of protein, up to 15% by weight of carbohydrates and up to 90 % polyacrylates, based on the total dry matter content of the binder.

The paper coating slip according to the invention is distinguished by good pigment binding capacity and high water retention capacity and leads to surface-finished papers with a high level of usability.

The invention is explained using the following exemplary embodiments.

Example 1;

2 base paper with a mass per unit area of 60 g / m is coated with a suspension of the following composition:

Blanc fixe 540 parts by weight Coated kaolin 460 " Binder mixture, 154 " consisting of 37.9% by weight nucleic acid 5.4 "" nucleotide 40.8 " ^M protein 15.9 "" carbohydrates Solids content: 40.5% PH value: 7.4

Brookfield viscosity (spindle 3, 20 ⁰ G)

Shear rate (rpm ''') Immediate measurement after 24 hours storage _e

50 rpm 310 cP 270 cP

100 "190 cps 170 cps

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Y / as se retention capacity: 49 s

This coating slip is distinguished in comparison to a coating slip with casein as a binder is characterized by a lower viscosity and a higher water retention capacity. The coated paper has the following properties:

Coat application 12 g / m ²

Whiteness 79.8%

(Zeiss leukometer, blue filter) Chatter resistance number (IGT Leipzig) A 1.0 m / s

The degree of whiteness and the drag coefficient are analogous to those of the comparison paper with casein as the binding agent.

Example 2:

A suspension of the following composition is analogous to that Example 1 applied to a base paper of 60 g / m 2:

Blanc fixe 540 parts by weight

Spreadable kaolin 460

Binder mix, 75 "

consisting of
15.9 wt. # Nucleic acid 19.9 "" nucleotide
55.6 "" protein
6.6 "" carbohydrates

Polyacrylate D 322 80 "

(VEB Chemical Works BUNA)

Solids content j 40.0%

pH 7.4

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BpookfieId viscosity (spindle 3, 20 ⁰ G)

Seer liking (U min) Immediate measurement after 24 hours of storage

50 rpm 176 cP 160 cP

100 rpm 110 cP 107 cF

Water retention capacity: 50 s

This coating mass has a comparatively higher water- retention as one with the same protein content Casein-containing suspension.

The surface-finished paper has the following coating properties on:

Line application A. 11 g / m ² Whiteness 79 9 % Chatter resistance number 1t 0 m / s

The paper has a contrast to the one coated with casein Comparison sample shows approx. 20% higher pick strengths.

Example 3:

ρ As in Example 1, a base paper with 80 g / m 2 is used. The coating slip has the following composition:

Blanc fixe 460 parts by weight

Brush kaolin 540 "

Binder mix, 71 "

consisting of

65.4% by weight nucleic acid 14.1 "" nucleotide

20.5 "" protein

Polyacrylate D 322 80 "

(VEB Chemical Works BUNA)

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Solids content: 40.8 % pH value 8.6

Brookfield viscosity (spindle 3 _t 20 ⁰ C)

Shear gradient (U min) Immediate measurement after 24 hours of storage

50 rpm 460 cP 650 cP

100 rpm 305 cP 420 cP

Water retention capacity: 51 s

Compared to a coating with the same protein content on casein, this suspension has slightly higher viscosities and a higher water retention capacity. The coated paper with the following properties has an approx. 20 - 30% higher pick resistance compared to the comparison sample with the same smoothness and whiteness values:

Line application A. 10 g / m ² Whiteness 80 .8 % Pickup resistance number 1 , 2 m / s

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Claims (1)

Claims 1d paper coating composition consisting essentially of a - binder and from pigments, which serves to improve the surface properties of paper and cardboard, characterized in that the binder is a mixture of nucleic acids and / or derivatives thereof, for _e, salts in the form of Nukleinaten as well as nucleotides alone or with proteins and / or carbohydrates, possibly in combination with other common binders, such as. B, thermoplastics. 2. Paper coating slip according to claim 1, characterized in that the binder, based on the total dry mass of the binder component, comprises up to 90% by weight of nucleic acid and / or sodium nucleinate and / or nucleotide, up to 30% by weight of protein and up to 15% by weight consists of carbohydrates. Paper coating slip according to claim 1, characterized in that the binder, based on the total dry mass of the binder fraction, consists of up to 90% by weight of nucleic acid and / or sodium nucleinate and / or nucleotide, up to 30% by weight of protein, up to 15% by weight of carbohydrates and consists of up to 90% polyacrylates. 709829/0725 ORIGINAL INSPECTED