DE1055940B - Process for the production of a fiber suspension - Google Patents

Description

GERMAN

The invention relates to a method for producing a pulp suspension, which in known Way to fibrous webs, such as paper and the like., Can be processed by precipitating water-insoluble substances from aqueous dispersions on the fibers suspended in water with Help of coagulants.

In normal papermaking processes, it is common to add fibers, for example by beating suspend and add an aqueous dispersion or emulsion of substances to the suspension, which are insoluble in water or can be made substantially insoluble. After that, a Coagulants, e.g. B. alum, stirred in for the purpose, the dispersion or emulsion of the water-insoluble Breaking up the substance so that the particles agglomerate and deposit on the fibers will. However, since coagulation occurs in the aqueous phase, there is considerable agglomeration before settling on the fiber, so that the water-insoluble substance on the fiber in proportion large lumps are deposited or cannot adhere to the fibers at all. It has also proven difficult to achieve a uniform one by the means described above Bringing over the fibers. Another well-known method is that in water suspended fibers a coagulant, e.g. B. alum, and then add this mixture to the watery To run in dispersion or emulsion of the water-insoluble substance. In both proceedings occurs coagulation before deposition on the fiber.

It is also known to ink-proof paper before or after the unsized paper its completion with a solution of water repellants consisting of high molecular weight compounds to be sprayed in water or organic solvents or to lead through a room, the said solutions in the form of a mist contains, whereupon the paper is dried at an elevated temperature of about 90 to 130 ° C.

According to the invention, a method of the type mentioned at the outset is carried out in such a way that an aqueous suspension of the fibers to be coated is acidified, then a polymeric heat-sensitive coagulant known per se, which consists of an organic compound which is an ether linkage R, is added to the acidified aqueous suspension —O — R ', where R is a polymeric group and R' is an alkyl or aryl group, and which is characterized in that it is soluble in water at a given temperature and becomes insoluble in water at an elevated temperature, then method for Manufacturing
a pulp suspension

Applicant:

Jointine Products Company Limited,
Lincoln, Lincolnshire (UK)

Representative: Dr. E. Wiegand, Munich 9,
and Dipl.-Ing. W. Niemann, Hamburg 1, Ballindamm 26, patent attorneys

Claimed priority: Great Britain January 31, 1955

Philip Harold Amphlett, James Dundas
and Geoffrey Lionel Hickson Woodthorpe,
Lincoln, Lincolnshire (UK),
have been named as inventors

the resulting mixture containing the heat-sensitive coagulant to an increased Temperature heated to prepare the fibers with the coagulant that heated Mixture cools, to the cooled mixture an aqueous dispersion of the water-insoluble fiber-covering Adding substance and a protective agent, stirring the resulting mixture, and stirring the Mixture heated to an elevated temperature to precipitate the fiber covering Effect substance on the prepared fibers.

The expression "water-insoluble substance" is to be understood as meaning all substances which are in Water are insoluble or can be made insoluble in water and which take the form of a "Aqueous dispersion or emulsion" in its natural state or to a dispersion or Emulsion can be made in water. From the expression "aqueous dispersion or emulsion" systems in water are comprised which contain particles of a solid or a liquid which

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has been stabilized by any of the known preservatives, both under acidic and are stable under alkaline conditions and in the presence of metallic salts, but are such Systems that are stabilized by cationic soaps are excluded from dispersions or emulsions to yield, which contain particles that have a positive electrical charge. Typical Examples of known protective agents are the fatty alcohol-ethylene oxide condensates and the sodium salt of alkylated naphthalenesulfonic acid.

Many water-insoluble substances that disperse or emulsify in water can be used are, and the following types of aqueous dispersion are given as examples, without the invention being restricted to them:

Rubber milk, either as it occurs naturally or as it is obtained by redispersing solid, vulcanized or unvulcanized rubber, and latices made from the following Substances: polyvinyl chloride, polyvinylidene chloride, copolymers of vinyl chloride and vinylidene chloride, Polyvinyl acetate, copolymers of vinyl acetate and vinyl chloride, polyacrylates, polymethacrylates and copolymers thereof, polyisoprene, polychloroprene, copolymers of butadiene and styrene, copolymers of butadiene and acrylonitrile, polystyrene, linseed oil, resin, alkyd resins, Ester gum, paraffin wax, petroleum jelly, carnauba wax, microcrystalline waxes, asphalt, Tar, pitch, bitumen and terpene resins, phenol-formaldehyde, urea-formaldehyde, melamine-formaldehyde resins and polyester resins. Mixtures of different latices can also be used, for example dispersions of vinyl polymers or copolymers with dispersions of butadiene acrylonitrile copolymers.

In the method of the invention, the dispersion of the water-insoluble substance is coagulated brought about on the surface of the fibers, and there is a progressive build-up of coagulate on the Fiber present until the dispersion of water-insoluble matter is completely exhausted. on in this way the fibers are coated evenly and uniformly.

The main feature of the process lies in the addition of a polymeric heat-sensitive Coagulant to the suspension of fibers in water prior to adding the aqueous dispersion a substance insoluble in water. This is done to ensure that there is coagulation on the fiber takes place and the water-insoluble substance is deposited on it.

Some of the known coagulants for aqueous dispersions have come into contact immediately effective with the aqueous dispersion, e.g. B. Acids and certain salts. Other coagulants have a delayed effect, so that intimate mixing of the coagulant with delayed Effect and the aqueous dispersion can be made and the coagulation after a Period follows. A third type are the coagulants known as heat-sensitive coagulants, which can be mixed into the aqueous dispersion and in which coagulation only occurs when the mixture is heated, for example above 15 ° C.

Some of these heat sensitive coagulants decompose when heated to release acid and thereby cause coagulation. Some,

which are very difficult to dissolve at room temperature can be added as a dispersion; they solve then rise when heated and cause coagulation. Some that are soluble at room temperature become insoluble at elevated temperatures. The latter class of heat-sensitive Coagulants are suitable for the process of the invention, namely polymeric organic heat-sensitive coagulants of a certain type that work at a given temperature in water are soluble and become insoluble at elevated temperature. Under the expression "elevated temperature" is to be understood as the temperature at which the solubility of the polymer is heat-sensitive Coagulant in water becomes so small that precipitation occurs. A typical example of this Coagulant is polyvinyl methyl ether, which is soluble in water at 20 ° C, but within the temperature range of 30 to 40 ° C is much less soluble and is precipitated. The alkylaryl polyethylene glycol ethers behave accordingly, but the elevated temperature at which the precipitation occurs is higher, namely in the range from 40 to 85 ° C

It is known to use polyvinyl methyl ether as a gelling or coagulating agent for aqueous dispersions and To use latices. In the method according to the invention, however, it comes down to the way in which the polyvinyl methyl ether is used to coagulate the aqueous dispersions or to cause latices on the surface of the fibers by first adding the polyvinyl methyl ether to it the fibers is precipitated, so that when adding the aqueous dispersion or the latex and when heated, coagulation can only occur where there is contact with the polyvinyl methyl ether takes place, namely on the fiber.

Various fibers, both natural and man-made, e.g. B. made of cellulose, wood, jute, hemp, Sisal, Manila hemp, wool, rayon, polyamide (nylon), leather, asbestos, glass, and mixtures of them, can be treated according to the method of the invention.

A preferred embodiment of the method according to the invention is as follows:

The fiber is beaten with water to form a uniform suspension, which is then mixed with an acid or an acidic substance or a salt of a trivalent or polyvalent metal, e.g. B. aluminum sulfate, hereinafter referred to as alum is treated. A polymeric thermosensitive coagulant, which has the property that it is at a temperature above z. B. 30 ° C insoluble in water is, like polyvinyl methyl ether, is then mixed into the fiber suspension in water, and the whole Mixture is heated to a temperature above 30 ° C for the purpose of making the polymeric heat-sensitive Precipitate coagulant on the fiber. The mixture is then brought to a temperature below Cooled to 30 ° C and an aqueous dispersion or emulsion of a substance insoluble in water is added, which a corresponding protective agent, e.g. B. anionic or nonionic soaps containing the are stable under alkaline and acidic conditions and in the presence of metal salts. Under these No coagulation of the dispersion takes place under conditions, however, during the subsequent rewarming at a temperature above 30 ° C the water-insoluble substance on the fiber in more uniform Way dejected.

It has been found that this procedure can be modified in the following ways:

The process as described can likewise be carried out up to the point where the polymeric heat-sensitive coagulant 5 is added to the mixture of water and fiber. The aqueous dispersion of a water-insoluble substance, which is protected in the manner described above, can then be added before heating to a temperature above 30 ° C. When heated to a temperature above 30 ° C, the water-insoluble substance is coagulated and partial precipitation takes place on the fiber, giving a less uniform product.

In a modified embodiment, the method can be as described up to the point be carried out on the mixture of water, fiber and polymeric thermosensitive Coagulant is heated to a temperature above 30 ° C. At that point it becomes special aqueous dispersion of the water-insoluble substance is added, and partial coagulation occurs. However, it has been found necessary to cool the mixture and then bring it back to a temperature heat above 30 ° C to cause complete precipitation.

The method can be further modified by adding the acid (or acids), the acidic substance or the salt of the trivalent or polyvalent metal together with the aqueous dispersion of water-insoluble substance, which is appropriately protected by soap, added instead of adding it to the fiber in the first stage of the process.

Although the preferred method is a more uniform precipitation of the water-insoluble substance results on the fiber and is easier to control, the other processes also deliver a product which a sheet or mass can be made which has useful properties.

The acid or acids, the acidic substance or the salt of a trivalent or polyvalent metal and The protective soaps are used for the purpose of coagulating the aqueous dispersion of the water-insoluble Prevent substance from heating and yet at the same time prevent coagulation at the increased Allow temperature.

The choice of acid or metal salts is determined by the type of aqueous dispersion to be used water-insoluble substance determined. Certain natural types of rubber milk are replaced by small ones Amounts of acid coagulate easily, while some synthetic dispersions have considerable amounts contain protective agent introduced during manufacture and cannot easily be coagulated by acid but can be coagulated by a metal salt such as alum.

On the other hand, the type of protective soap to be used is determined by the choice of acid or the Metal salt affects. Anionic soaps, which are made from fatty acids by neutralization with sodium, Potassium or ammonium hydroxide are not suitable as they are under acidic conditions or have no protective effect in the presence of certain metal salts.

Anionic soaps, which contain sulfonic acid groups, by sodium, potassium or ammonium hydroxides are neutralized, are stable under acidic conditions and can therefore be used with acid will; however, they are not intended for

suitable for use with salts of trivalent or polyvalent metals.

Nonionic soaps can be used with acids or salts of trivalent or polyvalent metals will. A typical example of this is a fatty alcohol-ethylene oxide condensate.

The amount of acid or acids, acidic substance or salt of trivalent or polyvalent metal, which are used in one of the methods described above, can be changed within wide limits will. Furthermore, the amount used in this way affects the amount to be used Protective soap and in turn regulates the amount of polymeric heat-sensitive coagulant required.

The table below gives the range of proportions of these ingredients used with wood fiber where all parts are based on dry weight:

A. B. 100 100 Aqueous dispersion of chewing 50 50 100 2 Polymeric heat sensitive 15th 3 10 1

Columns A and B represent the wide limits within which these constituents change can be. The type of fiber and the particular aqueous dispersion also influence the the water-insoluble substance used, the quantities of the various components required, and it is necessary to conduct a series of experiments to determine the preferred amounts. It has been found that the best practice is to use a large amount of alum and use the proportions shown in column A for the various components. The alum is then progressively reduced with a corresponding decrease in the amount of Protective soap and the polymeric heat-sensitive coagulant. There is no exact proportional Relationship between these components, and it may be necessary to use one or the other component to change. Columns A and B are intended to show the approximate proportions required. The required amount of acid can be determined by an appropriate procedure.

In the following examples of the process, all parts given are parts by weight.

Example I.

5 parts of wood fiber were beaten to a suspension with 1000 parts of water. This suspension was then acidified to a _pH value of 3.5 with 20 parts of a solution of alum, containing 20 parts of aluminum sulfate in 80 parts of water. 5 parts of a solution which contained 15 parts of polyvinyl methyl ether in 85 parts of water were added to the acidified suspension, and the whole was then heated to 35 ° C. with gentle stirring. As soon as this temperature was reached, the suspension was cooled and the following mixture was added:

1

8 parts of an aqueous dispersion of 40 parts of butadiene acrylonitrile copolymer and

60 parts of water,
5 “a solution of a nonionic soap containing 10 parts of soap in

90 parts of water,
100 "water.

The suspension was then reheated to 35 ° C. with gentle stirring, and the resulting treated fiber was formed into a sheet by removing the excess liquid.

Example II

5 parts of ground leather were beaten to a suspension with 1000 parts of water. The fiber was entgerbt by adding 5 parts of ammonia (SG 880), so that the suspension assumed a _pH value of 7.5. The suspension was then adjusted to a _pH value of 3.5 with alum solution containing 20 parts of aluminum sulfate in 80 parts of water.

The acidified suspension was 5 parts of a solution containing 15 parts of polyvinyl methyl ether contained in 85 parts of water, and the whole was heated to 35 ° C with gentle stirring. As soon as this temperature was reached, the suspension was cooled and the following mixture admitted:

8 parts of an aqueous dispersion which contained 40 parts of butadiene acrylonitrile copolymer and 60 parts of water,
5 ,, a solution of a nonionic soap which contained 10 parts of soap in 90 parts of water,
100 "water.

The suspension was then reheated to 35 ° C. with gentle stirring, and the resulting treated fiber was formed into a web by removing the excess liquid.

Example III

5 parts of wood fiber were beaten to a suspension with 1000 parts of water. This grant was then with 10 parts of an alum solution containing 10 parts of aluminum sulfate in 90 parts of water, acidified. The acidified suspension was 2 parts of a solution containing 10 parts of polyvinyl methyl ether contained in 90 parts of cold water was added and the whole was stirred gently heated to 35 ° C. As soon as this temperature was reached, the suspension was cooled and the following Mixture added:

5 parts of natural rubber milk, which 60 parts

Contains heveak rubber and 40 parts of water,

1 part of a 4% solution of formaldehyde in water,

6 parts of a solution of a nonionic soap

(Fatty alcohol-ethylene oxide condensate) with a content of 1 part soap in 90 parts water, 100 "water. ^ö

The suspension was then reheated to 35 ° C. with gentle stirring, and the resulting treated fiber was formed into a web by removing the excess liquid.

940

Example IV

5 parts of long-fiber asbestos were beaten to a suspension with 1000 parts of water. This suspension was then acidified to a _pH value of 3.5 with 20 parts of a solution of alum, which consisted of 20 parts of aluminum sulfate and 80 parts of water. 5 parts of a solution containing 15 parts of polyvinyl methyl ether in 85 parts of cold water were added to the acidified suspension, and the whole was heated to 35 ° C. with gentle stirring. As soon as this temperature was reached, the suspension was cooled and the following mixture was added:

6 parts of an aqueous dispersion of 40 parts

Butadiene acrylonitrile copolymer and 60 parts of water,
6 "a solution which contained 1 part of fatty alcohol-ethylene oxide condensate in 99 parts of water,
100 "water.

The suspension was then reheated to 35 ° C. with gentle stirring, and the resulting treated fiber was formed into a web by removing the excess liquid.

Example V

5 parts of wood fiber were beaten to a suspension with 1000 parts of water. This suspension was then acidified to a _pH value of 3.5 with IO ¹ parts of a solution of alum, which contained water, 10 parts of aluminum sulfate in 90 parts.

2 parts of an alkylaryl polyethylene glycol ether ("Emullat 29") were added to the suspension, and the whole was heated to 80 ° C. with gentle stirring. Once this temperature was reached, the suspension was cooled and the following mixture was added:

6 parts of an aqueous dispersion of 40 parts

Butadiene acrylonitrile copolymer and 60 parts of water,
6 of a solution containing 1 part of fatty alcohol

Ethylene oxide condensate contained in 99 parts of water,
100 "water.

The suspension was then reheated to 80 ° C. with gentle stirring, and the resulting suspension treated fiber was formed into a web by removing the excess liquid.

Example VI

5 parts of wood fiber were beaten to a suspension with 1000 parts of water. This suspension was then acidified with 10 parts of an aqueous solution of 4η-acetic acid. The pissed off Suspension was 6 parts of a solution, which 10 parts of polyvinyl methyl ether in 90 parts of cold Containing water was added and the whole was reheated to 35 ° C. with gentle stirring. As soon this temperature was reached, the suspension was cooled and the following mixture was added :

5 parts of a natural rubber milk made from 60 parts of heveak rubber and 40 parts Water,

1 part of a 4% solution of formaldehyde in water,

Claims (5)

5 parts of a solution of an anionic soap which contained 5 parts of soap in 95 parts of water, 100 “water. The suspension was then reheated to 35 ° C. with gentle agitation, and the resulting treated fiber was formed into a sheet by removing the excess liquid. Example VII 10 parts of wood fiber were whipped into a suspension with 1000 parts of water. 5 parts of a solution which contained 20 percent by weight of aluminum sulfate dissolved in water were then added to this suspension. 10 parts of a solution containing 10 parts of polyvinyl methyl ether in 90 parts of water were added to the suspension, and the whole was heated to 35 ° C. with gentle stirring. As soon as this temperature was reached, the suspension was cooled and the following mixture was added: 4 parts of an aqueous dispersion which consisted of the following: 100 parts of zinc oxide, 5 "nonionic dispersant, 195" water. The mixture was then reheated to a temperature of 40 ° C. with gentle stirring and the resulting treated fiber formed into a web by removing the water. Other inorganic substances which are insoluble in water, e.g. Titanium dioxide, clay, alumina, and indeed any inorganic substance which is insoluble in water and which can be made into a dispersion with water can be used. Claims. 1. A process for the production of a fiber suspension, which in a known manner to form fiber webs, such as paper and the like, can be processed by precipitating water-insoluble ones Substances from aqueous dispersions on the fibers suspended in water with the help of coagulants, characterized in that an aqueous suspension of the to be coated Acidified fibers, then the acidified aqueous suspension a known polymer add heat-sensitive coagulant which consists of an organic compound which contains an ether linkage R — O — R ', where R is a polymeric group and R 'is an alkyl or aryl group, and which are thereby is characterized by the fact that it is soluble in water at a given temperature and at an elevated temperature Temperature becomes insoluble in water, then the resulting mixture, which is the heat-sensitive Contains coagulant, heated to an elevated temperature in order to prepare the fibers with the coagulant which is heated Mixture cools, to the cooled mixture an aqueous dispersion of the water-insoluble fiber-coating substance and a protective agent are added, the resulting mixture is stirred and the stirred mixture is heated to an elevated temperature to precipitate the fiber-covering Effect substance on the prepared fibers. 2. The method according to claim 1, characterized in that the aqueous suspension of the to covering fibers are acidified with acidic salts of trivalent or polyvalent metals will. 3. The method according to claim 1 or 2, characterized in that the polymer is heat-sensitive Coagulant polyvinyl methyl ether is used. 4. The method according to claims 1 to 3, characterized in that a protective agent nonionic soap is used. 5. The method according to any one of claims 1 to 4, characterized in that the aqueous suspension is acidified to the article to be coated fibers to a _pH value of about 3.5, and the acidified suspension was added an organic compound of the type referred to as a polymeric heat-sensitive coagulant which becomes water-insoluble when heated to a temperature of 30 to 35 ° C, and that the mixture containing the heat-sensitive coagulant is heated to a temperature of about 35 ° C to deposit the coagulant on the fibers. Considered publications:
German Patent No. 924 185;
French Patent No. 822,787;
Noble, Latex in industry, 1953, p. 357. © 909 507/502 4.59