DE1446609B1 - Process for the production of plastic-containing papers by adding plastic dispersions to the fiber material prior to sheet formation - Google Patents

Description

It is known that for the production of finished papers the Aqueous paper stock at any stage prior to the formation of the paper sheet Add plastic dispersions and, if necessary, the plastic particles through Addition of salts of polyvalent metals or other precipitating and fixing agents the cellulose fibers can precipitate or bind to the fibers. That way pretreated pulp is then subsequently drained in the usual way processed into paper.

So far, anionic and nonionic plastic dispersions have been used for this purpose used, which, however, are usually only added in small amounts to the pulp can. If larger proportions of such dispersions are to be added, so are relatively large amounts of precipitants or fixatives that are water-soluble and cationic are required to make the dispersed plastic particles on the cellulose fibers knock down. In addition, the known methods occur during dewatering easily disrupted by precipitation of coagulated plastic particles on various Place the paper machine, for example on the wires, on the press rolls and by gluing the paper web onto the drying cylinders. They also accumulate Plastic particles often stick to one of the leaf surfaces, which may be the case with the subsequent calenders caused the paper web to stick to the rollers. By The papers are also too coarse and unevenly deposited of the plastic particles mostly more or less inhomogeneous. All of these difficulties become likely caused by the fact that the hydrophobic plastic particles themselves have no affinity to the paper fiber and form conglomerates during precipitation.

Improved processes are also known in which plastic dispersions which contain cation-active water-soluble dispersing agitators. In In this case, the plastic separates even without the addition of precipitants largely on the fibers, but the plastic deposition is very irregular and gross. This leads to similar disturbances, especially with larger plastic additives, as described above with regard to the use of anionic dispersions became.

It has now been found that plastic-containing papers are advantageous can be produced by adding plastic dispersions to the fibrous material present in aqueous suspension of practically insoluble in water, cation-active copolymers of N- or C-vinyl substituted aromatic and / or heterocyclic compounds, the contain at least one quaternary nitrogen atom in the core or in side chains, and from mixed with sparingly water-soluble olefinically unsaturated compounds and this The mixture is then dewatered in the manner customary in papermaking. Such Copolymers draw from an aqueous suspension largely very evenly and in fine distribution on cellulose fibers or cellulose-containing fibers, and one receives - without disturbances of the kind mentioned above and without the addition of Precipitants or fixing agents - very homogeneous papers, the properties of which are largely can be varied.

Plastic dispersions which can be used according to the invention can be advantageous by the method of U.S. Patent 2,891,025 by Mixtures of the corresponding quaternary ammonium compounds with the corresponding olefinic unsaturated compounds in the presence of cation-active and optionally additionally of non-ionic dispersants in aqueous dispersion with the addition of suitable ones Catalysts, such as hydrogen peroxide, polymerize.

Suitable cation-active dispersants are, for example, salts of fatty amines and oxethylated fatty amines. Suitable non-ionic dispersants are z. B. Oxäthylierungsprodukte of fatty alcohols and protective colloids, such as polyvinylpyrrolidone or polyvinyl alcohol.

Copolymers which can be used according to the invention can also be used in suitable Solvents prepared and then optionally with the addition of suitable dispersants dispersed in water.

N- or C-vinyl-substituted aromatic and / or heterocyclic Compounds within the meaning of the invention are, for example, N, N, N-trimethyl-N- (4-vinylbenzyl) - ammonium chloride, N - vinylbenzyl - N, N - dimethyl - N - benzylammonium chloride, p - vinylbenzylpyridinium chloride, 1,2-dimethyl-5-vinylpyridinium methosulfate, 1-methyl-2-vinylpyridinium methosulfate, 1-methyl-2-vinylquinolinium methosulfate, 1-benzyl-4-vinylquinolinium chloride, N-vinyl-N'-methylimidazolium methosulfate, N-vinyl-N'-benzylimidazolium chloride and 1-vinyl-3-methylbenzimidazolium methosulfate.

In terms of sparingly water-soluble olefinically unsaturated compounds of the invention are, for example, the esters of unsaturated carboxylic acids, such as acrylic acid and methyl, butyl or cyclohexyl methacrylate; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl halides such as vinyl chloride and vinylidene chloride as well Acrylonitrile, styrene, α-methylstyrene, butadiene, 2-chlorobutadiene, isoprene, esters of Maleic and fumaric acid or, in addition, vinyl ethers, such as vinyl isobutyl ether. aside from that the copolymers can also be added in amounts of up to about 10 percent by weight water-soluble olefinically unsaturated monomers such as acrylic and methacrylic acid amide, included in polymerized form.

The proportion of N- or C-vinyl-substituted aromatic and / or heterocyclic ammonium compounds in the copolymer is advantageously between 1 and 15 percent by weight. However, it can also be 200/0 and more, so far only the copolymers in question are sparingly soluble and easily dispersible in water are.

The addition according to the invention of such cation-active dispersions can after the usual opening of the cellulose fibers and optionally after them Milling to the pulp present in a relatively high concentration, for example in the Dutch.

The quantity ratio between plastic and fiber can vary widely Any limits can be chosen. According to the invention, in addition to papers with only minor Plastic contents are also produced in which the amount of plastic the amount of cellulose fibers possibly far exceeds. It is particularly surprising that the polymer particles even with high plastic additives such. B. at one Plastic to fiber ratio of 1: 1, generally complete and uniform distributed on the fibers are retained. Since accordingly the water runs off practically clear during drainage, step on the sieve, im Drainage system and on the presses no disturbances, and sheet formation takes place without difficulty. Together with the plastic particles, if necessary added fillers such as kaolin or titanium dioxide generally work very well on the Cellulose fibers withheld.

If plastic-rich papers are to be produced, this can be done Fiber dispersions with a plastic content of 20 to 50 percent by weight slowly add in portions. For the production of low-plastic papers, however, it is advantageous, the pulp corresponding dispersions with a plastic content of about 3 to 10% to be added in order to distribute the To achieve plastic particles in the fiber. Also in some cases it can be It may be advantageous to dilute the pulp before adding the plastic dispersion.

After a mixing time of about 10 to about 30 minutes, the plastic particles are generally drawn onto the cellulose fibers. The pulp can then in the usual Way to be fed to the paper machine. If the pulp dispersions become harder, Polymers, d. H. of polymers that soften at temperatures above 25 ° C, added, it is generally expedient to remove the pulp during the drawing up the plastic particles or subsequently, for example by introducing Heat steam in the Dutchman or by adding hot water. With many Copolymers of styrene or vinyl chloride usually suffice for this purpose of about 50 ° C. This facilitates drainage during leaf formation. Such tempering is generally not necessary in the case of soft polymers.

The type and speed at which the plastic particles are drawn up depend not only on the structure of the polymers but also on the type and amount of dispersants addicted. For example, the winding speed decreases to a certain extent Degrees with the amount of cationic dispersant increasing; she takes against it increasing amount of non-ionic dispersants and is also of the- -Dependent on pre-treatment of cellulose fibers. Also for the properties, in particular for sizing, the finished paper can be the type of dispersant used and protective colloids are of importance- (see. Example 4).

Depending on whether the fiber material is cation-active dispersions according to the invention hard or soft copolymers are added to give papers with very different properties. If one uses dispersions of at room temperature ; soft copolymers, soft and optionally sized papers are obtained with elasticity and suppleness, as previously with the help of known processes, for example by adding plasticizers, not produced i could be. As in contrast to the usual procedures of consecration of Paper this effect is not based on the hygroscopic properties of the plasticizers, the soft character of the paper is retained even after drying. Such After calendering, some papers are oil- and waterproof and can for example can be used with advantage in the packaging industry. If you use it against it Dispersions of polymers which are hard at room temperature and which, for. B. predominantly from Styrene: or vinyl chloride are produced, more or less hard ones are obtained Papers that show stiffness, sound hardness and stability and for production for example playing cards, booking papers, packaging boxes and corrugated cardboard are suitable.

The advantageous properties of such papers are generally by a calendering, d. H. a post-treatment under pressure and heating like her is common in the paper industry is still improved.

With a very high content of hard polymers, for example of more than 40 percent by weight, the papers become thermoplastic at elevated temperature deformable. If such papers are calendered under sufficient pressure, then this is obtained transparent and film-like products that have largely lost their paper character to have. The pressures and temperatures required depend on the type of used Depending on the polymers and are between about 5 and 10 atmospheres or between about 80 and 180 ° C. Paper produced according to the invention is also distinguished by the Compression due to good wet strength.

The parts given in the following examples are parts by weight. Example 1 To 100 parts of unbleached sulphate pulp; which has been ground and defibrillated in the usual way in a Hollander with the addition of 3000 parts of water, 400 parts of an approximately 50% aqueous dispersion of an emulsion polymer of 80 parts of vinylidene chloride, 20 parts of butyl acrylate and 3 parts of N-vinyl-N'- methylimidazolium methosulfate, which contains 3 parts of polyvinylpyrrohdone with a K value of 30 as a protective colloid and 2 parts of diethyl dodecylammonium sulfate as a cationic dispersant. The pulp is then allowed to circulate in the hollander for 15 minutes with the grinding roller raised, the plastic particles being absorbed practically quantitatively on the cellulose fibers. Then the pulp is dewatered on the paper machine as usual. A paper is obtained which, after drying, is very soft and pliable and which becomes oil- and water-tight when calendering is carried out in the customary manner. For example, it can be used to advantage in the packaging industry. EXAMPLE 2 80 parts of a 20% plastic dispersion composed of 80 parts of butyl acrylate are added to a mixture of 3000 parts of water, 50 parts of sulphite pulp and 50 parts of bleached sulphate pulp, each of which is suitable for producing glassine. 20 parts of acrylonitrile, 3 parts of N-vinyl-N'-methyl-imidazolium-methosulfate and 1.5 parts of oxethylated tridecylamine as a dispersant had been prepared by emulsion polymerization in 150 parts of water. The fiber is then mixed thoroughly for 15 minutes and then processed into glassine in the usual way. A soft and pliable glassine is obtained which has a relative wet strength of about 25 % . (The relative wet strength was measured according to Brecht, Wissenschaftliche Publications der Technische Hochschule Darmstadt [1947], Vol. 1, Book 2, pp. 33 to 47.) Glassine produced in the same way without the addition of plastic has a relative wet strength of only 6 ° / o. It's much harder and brittle. If it is softened as usual by adding glycerine or magnesium chloride, its strength properties are significantly impaired. Example 3 100 parts of a mixture of bleached sulphite and sulphate pulp are mixed with 3000 parts of water in a laboratory mixer with 200 parts of a 40% aqueous dispersion of an emulsion copolymer of 90 parts of styrene, 10 parts of butyl acrylate and 3 parts of N-vinyl-N '-methylimidazolium methosulfate is added, which contains 3 parts of diethyl dodecylammonium sulfate and 2 parts of oxethylated sperm oil alcohol as a dispersant. A cardboard box is then produced from the pulp in the usual way by dewatering and is pressed in a laboratory calender at 140.degree. The result is a very hard cardboard box with a scratch-resistant surface which, however, is not brittle and which has the sound hardness desired for playing cards.

Example 4 100 parts of bleached sulphate pulp are made in a hollander Whipped in the usual way with the addition of 3000 parts of water and ground. The pulp are slowly and as evenly as possible directly in front of the grinding roller des Holländers 55 parts of an approximately 4% aqueous dispersion of an emulsion copolymer from 70 parts of butyl acrylate, 30 parts of acrylonitrile and 10 parts of N-vinyl-N'-methyl-imidazolium methosulfate, the dispersant 1 part diethyldodecylammonium sulfate and 3 parts polyvinylpyrrolidone contains a K value of 30, added. The pulp is then processed in the usual way dewatered on the paper machine. A paper is obtained which is well sized against ink and that is more pure white than a known for comparison with the addition of resin glue Wise made paper.

Example s In a Hollander become a suspension of 100 parts bleached sulphate pulp with a freeness of about 40 (see leaflet no.107 of the association of pulp and paper chemists and engineers) in 3000 parts of water at upscale Milling roller 200 parts of an approximately 35% aqueous dispersion of a copolymer from 70 parts of vinyl chloride, 30 parts of butyl acrylate and 3 parts of N-vinyl-N'-methyl-imidazolium methosulfate added, the 3 parts of dimethyl dodecylammonium sulfate and 2 parts oxethylated Contains sperm oil alcohol as a dispersant. The pulp is then in the Hollander heated to about 45 ° C by adding hot water or by introducing steam and then dewatered on a paper machine as usual. One receives a hard, largely paper-like, but thermoplastically deformable product of high stability. By pressing at about 120 ° C under a pressure of 20 to 40 kg / cm2 can be used to produce a material that is largely transparent and resembles a polyvinyl chloride film in terms of its density and surface hardness Has.

Claims (1)

Claim: Process for the production of plastic-containing papers by adding aqueous plastic dispersions to that present in aqueous suspension Pulp, characterized in that the pulp is dispersed per se known, practically insoluble in water, cationic copolymers firstly N- or C-vinyl-substituted aromatic or heterocyclic compounds, which contain 1 quaternary nitrogen atom in the core or in a side chain, and secondly mixed with sparingly water-soluble olefinically unsaturated compounds and this The mixture is then dewatered in the manner customary in papermaking.