DE1945104A1 - Process for the production of paper with improved properties - Google Patents

Description

FARBWERIiE HOECHST AG., Formerly Master Lucius & Brüning File number: Fw 62o6

August 29, 1969 -Dr.MD/mo

Process for making paper with improved properties

It is known to manufacture papers by extrusion or melt coating with films made of polyethylene or copolymers made of ethylene / vinyl lace tat to cover., Usually it is about Packaging papers, which in this way obtain improved impermeability to water, water vapor, grease and oil.

Such papers are costly to produce, and so are those that are applied Films are relatively thick.

It is also known that these disadvantages can be eliminated by using solid polyethylene or its copolymers instead aqueous dispersions of the solid polymers are used. This gives papers which have good water vapor tightness own; For reasons of stability, these dispersions usually contain high proportions of one or more emulsifiers anionic or nonionic character, so that due to the residues of emulsifiers remaining in the coating only have a moderate water resistance.

It has now been found that the water sensitivity of the Coating can then be improved if ethylene copolymer dispersions are used used, the production of which is described in German patent application P 17 2o 667.6.

These dispersions are copolymers of ethylene and ethylenically unsaturated compounds, and optionally other polymerizable compounds which, at elevated pressure and temperature in the presence of radical initiators, but are made without emulsifiers. as

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Ethylenically unsaturated compounds are the alkali salts called by unsaturated acylamide-N-sulfonic acids.

Other polymerizable compounds are preferred Acrylic or "methacrylic acid esters in question,

The use according to the invention of these copolymer dispersions in the production of paper can either. by Can be added to the paper pulp or by impregnation of the paper surface.

The addition to the paper pulp is expediently carried out in such a way that the copolymer dispersion is added to the paper pulp and the copolymer is flocculated after homogeneous distribution by flocculants *, preferably aluminum sulfate. such as kaolin, china clay, etc. and sizing agents such as resin, glue, made. After the flocculation, the copolymer remains almost completely in the paper in finely divided flakes after dewatering on the screen. Following the preparation in a known manner and drying the paper web this is calendered at elevated pressure and elevated temperature. In this way, film formation of the individual flakes of the copolymer is achieved. The temperature of the calender rolls should be 12o - 180 ⁰ C, preferably l - amount to 15o C, the pressure at 5o - 5o are preferably 60 to 12o kg / cm roll length 2oo kg / cm.

The amount may vary depending on the intended use at Io - 7o wt .- ^, preferably at Jo - 5o wt -. ^ Copolymer are based on dry pulp.

The papers produced in this way have, depending on the polymer content, more or less the character of plastic films. They show very little water absorption, a smooth, shiny surface, and increased trans-

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parenz, good grease and water vapor tightness and a lower sound hardness.

The impregnation of the paper surface with the copolymers mentioned is expediently carried out so that the finished paper web on an impregnation, for example one Size press, immersed in a copolymer dispersion diluted with water and then dried in a known manner and how as described above, calendered under elevated pressure and at elevated temperature. The concentration of the impregnation liquor should at 100 - 800 g / l of a 40 ^ igen dispersion, preferably at 3oo - 5oo g / l. The exact concentration is determined by the desired effect and the absorbency of the paper.

The paper web to be impregnated can be sized, filled or made wet-strength before the impregnation.

i
The impregnation gives a sheet-like paper. The surface is particularly smooth and shiny, so that, depending on the thickness of the coating, it can be difficult or impossible to write on with normal ink or ballpoint pens.

According to the invention by using the copolymer in the Papers produced in bulk or on the surface are also characterized by the absence of any tendency to curl, what is particularly advantageous for thin and highly ground papers. The fiber material can be bleached and unbleached Sulphite and sulphate pulp, semi-pulp, high-yield pulp, use all types of wood pulp and waste paper. In addition, synthetic fibers and regenerated cellulose fibers are used possible.

Due to their surface properties, the papers produced according to the invention can be used as release papers for self-adhesive Use flooring panels or labels and foils, for which up to now the considerably more expensive or cumbersome ones

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producible siliconized or with chromium aluminum stearate coated papers are used.

When using highly ground cellulose, the copolymer can be incorporated by the use according to the invention Produce parchment substitute or parchment paper with improved grease and water resistance dispense with the separate addition of a plasticizing product can, as the hardness of the sound is greatly reduced by the copolymer.

The use of the copolymer according to the invention leads to improved ribbing resistance in the case of highly filled label papers. In the case of packaging papers for metal parts, for example machine parts, the inventive Use of the copolymer as a result of the good water repellency and the low water vapor permeability of the paper Corrosion of the metals excluded or largely avoided.

example 1

100 parts of dry, bleached spruce sulphite pulp are ground in a 4 ^ iger aqueous suspension in the cone refiner to a freeness of J6 ^O SR (Schopper-Riegler). To this suspension is added loo parts of an approximately $ 3o dispersion of a copolymer of 96.3 wt -.% Ethylene, 2.3 wt -.% Methyl methacrylate and 1.4 wt .- ^ di-K-methacrylamidosulfonat added and stir the suspension until it is evenly distributed for about 15 minutes. The pH of the suspension is then adjusted to about 4.5-5 by adding a 10% Al-sulfate solution, while stirring. Here and during the subsequent stirring time of about 15 minutes, the copolymer precipitates out in fine flakes.

The suspension is then mixed with water to a solids content diluted by approx. $ 0.5 - $ 1, and paper sheets from the pulp educated. After drying at loo - llo ° C, the

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Sheets of paper are sent through a calender (steel / paper rollers) at a temperature of ljü> o C and a pressure of 60 kg / cm. The paper obtained in this way is eminently suitable as so-called release paper; it possesses the following technological Data:

Table 1

Sulphite paper Sulphite paper without copolymers. with copolymer *.

m weight (g) 92.1 90.5

Dry tear strength (Rkm) 4.5 3.56

Elongation dry {%) 2.7 5, ο

Wet tear strength (Rkm) - o, 55

Elongation wet (^) (l) 2.8

Cobb test (g / m ² ) 155 15.5

PLG value (see) 2 loo

Example 2

From a highly ground, bleached spruce sulfite pulp with a freeness of 75 ° SR, paper sheets are formed as described in Example 1, but without the use of the copolymer in the bulk. The leaves are dried at 100 - Ho ⁰ C and then in a solution of 500 g / l of a 40 #igen copolymer dispersion of 57 wt .- ^ ethylene, 40 wt .- % methyl methacrylate and 3 wt .-% Di-K -methacrylamidosulfonate dipped and dried again. Finally, the sheets are calendered at a temperature of 180 ° C. and a pressure of 60 kg / cm. An improved parchment replacement paper is obtained with a greatly reduced sound hardness. The dry layer of copolymer is approx. 10% by weight , the technological values are as follows:

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β -

Tabel

m -weight dry tensile strength (Rkm) dry elongation {%) wet tensile strength {%) wet elongation {%)

Cobbtest (g / m)

Pett tightness according to Tappi T 454 m - 44

Parchment substitute Parchment substitute without copolymers - with copolymers! -

risat

60.7
3.99
1.7

0.09
ο, 6
7o

middle
(isolated
Carbon copies)

sat

66.9 3.28

1.7

1.48

1.0

good (no through

Example 5

100 parts of dry, unbleached sulfate pulp are ground to 42 ° SR in the cone refiner at a consistency of 4 %. Then 3 parts of resin glue (Collodin D) are added to the stock suspension and the mixture is stirred until it is homogeneously distributed. It, 75 parts of a 4o will follow Copolymerlsat dispersion from 89 * 8 wt -.% Ethylene, 6.8 wt, -. # Methylmethacrylate and 3.4 wt .- # Di-K-methacrylamidosulfonat added and distributed, this also homogeneous. With the aid of an aqueous aluminum sulfate solution, the pH is adjusted to 4.5, with both the resin glue and the copolymer flocculating. After a stirring time of approx. the previously milky, cloudy water in the suspension has cleared completely. The pulp is now processed into paper in the usual way on the paper machine. Finally, the paper web is "calendered at a temperature of 130 ° C. and a pressure of 100 kg / cm". A wrapping paper is obtained which has very little water absorption and is therefore particularly suitable for packaging machine parts.

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Tabel

2
m weight

Dry tear strength (Rkm) Dry elongation {%) Wet tear strength (Rkm) Wet elongation

Cobbe test (g / m ² )

ο burst pressure (kp / cm) arch height (mm)

Wrapping paper without Wrapping paper with Copolymer Copolymer 74.1 loo, 7 2.7o 2.78 4.1 4.1 • o, 28 2.77 o, 8 4.2 54.6 5.1 3.4 5.7 5.5 5.4

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Claims (1)

Patent claims (1) Process for making paper with improved Properties, characterized in that the paper pulp prior to sheet formation, an aqueous dispersion of a copolymer of ethylene with di-alkali metal salts of unsaturated ones Acylamide-N-sulfonic acids and optionally other polymerizable compounds are added to these Dispersion due to the addition of mineral acid or aluminum sulfate precipitates and the paper web after complete or partial drying at elevated temperature and elevated Calendered print. (2) Process for the production of paper with improved properties, characterized in that the finished Paper web impregnated in an aqueous dispersion of the copolymers listed in claim and after complete calendered or partial drying at elevated temperature and pressure. (3) Method according to claim 1, characterized in that one related to the paper pulp Io - 7 o wt .- ^ copolymers on dry pulp, adds. (4) Method according to claim 2, characterized in that the finished paper web is impregnated in a solution containing 300-8oo g / l of the copolymers mentioned in claim 1 contains. 109; -ι 4/1777