CH629228A5 - Cellulose graft copolymer in fibre form, process for the preparation thereof, and the use thereof - Google Patents

Description

The present invention relates to a cellulose graft-mixed polymer in fiber form, which has a cellulose structure and grafted-on side chains of polymer residues. Furthermore, the present invention relates to a method for producing the cellulose graft copolymer according to the invention in fiber form, and to its use as a component of an absorbent material.

The cellulose graft copolymer in fiber form according to the invention strongly absorbs water and aqueous liquids, and it should therefore be used in particular in products which serve to absorb aqueous liquids, in particular body fluids, such as diapers, monthly hygiene products such as sanitary napkins and tampons, dressing materials, surgical materials Sponges and the like.

Cellulose fibers are a starting material for many commercially available absorbent products. Because of the constant demand to improve the absorbency of these products, there is a continuing need to improve the absorbency of natural cellulose fibers and regenerated cellulose fibers. Since the cellulose is a naturally occurring polymer and is not produced synthetically, the structure of this material is not accessible to the changes due to the mixed polymerization methods used in the production of synthetic polymers. However, the absorbance of cellulosic fibers is due to the modification of their chemical structure

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The known techniques consist in (1) replacing the original hydroxyl groups of the cellulose fibers with new chemical groups, (2) linking the cellulose chains into a network, (3) introducing and crosslinking new groups, or (4) Graft polymer side chains onto the cellulose framework or backbone.

These chemical changes are generally carried out in liquid (preferably aqueous) slurries, after which the modified fibers formed are dried to pulp paperboard, which is then ground to pulp fluff or fluff. Although these conventional processes generally result in absorbent cellulose fibers, the fibers are generally very brittle and easily lose their fiber structure, so that they become fluffy to extremely short fibers or a powder by mild mechanical treatment, for example when the pulp board is milled into the pulp disintegrate. It has also been found that these prior art products, when dried from aqueous slurries to pulp paperboard, tend to form strong bonds between the fibers and to form aggregates of a hard, knot-like material similar to a solid resin, a process who is known as a cornification.

These knots are non-fibrous and, when the pulp is ground to a fluff, will either ground to a powder or will remain as a whole, so these products, regardless of their form, are not suitable as absorbent dressing materials. Although the prior art modified cellulosic fibers have greater absorbency compared to the unmodified cellulosic fibers, they acquire this property at the expense of reduced softness and at the cost of losing other desirable fiber properties.

The aim of the present invention was to provide a cellulose graft copolymer in fiber form which maintains the fiber quality of unmodified cellulose fibers, thereby avoiding the above-mentioned difficulties of conventional modified cellulose fibers and which, on the other hand, has a substantially greater absorption capacity compared to unmodified cellulose fibers.

Surprisingly, it has been shown that the desired goals can be achieved by a cellulose graft copolymer in fiber form which has a cellulose backbone and grafted-on side chains of polymer residues which have resulted from a double bond opening polymerization of olefinically unsaturated monomer molecules, and the total weight of 10.5 to 90% of the cellulose graft copolymer, the polymer side chains being composed of ionic and non-ionic monomer units in a weight ratio which is defined in more detail below.

The present invention therefore relates to a cellulose graft copolymer in fiber form, which is characterized in that it has a cellulose skeleton and grafted-on side chains of polymer residues which have resulted from a double-bond opening polymerization of olefinically unsaturated monomer molecules, and the 10.5 to 90% of the Represent the total weight of the cellulose graft copolymer, the polymer side chains being composed of ionic and non-ionic monomer units, and 10-80% of the total weight of the cellulose graft copolymer consisting of ionic monomer units and 0.5-60% of the total weight of the cellulose graft copolymer unit consisting of non-ionic.

In the cellulose graft copolymer according to the invention, the grafted-on polymer side chains must therefore be composed of ionic and non-ionic monomer units which have been formed by double bond opening polymerization of corresponding olefinically unsaturated monomer molecules. It should be noted that in order to achieve the desired properties, it is only necessary that the stated amounts of ionic monomer units and non-ionic monomer units are present in the side chains.

5 In this case, side chains can be present in the cellulose graft copolymer which are composed only of ionic monomer units and, in addition, side chains can be present which are only composed of non-ionic monomer units or the side chains in question can comprise both ionic and non-ionic monomer units . It is only essential that, based on the entire cellulose graft copolymer, the stated ratio of ionic and non-ionic monomer units is observed.

The cellulose graft copolymers in fiber form according to the invention can have a cellulose backbone which is that of natural cellulose or else one which is that of regenerated cellulose.

A preferred cellulose graft mixed polymer according to the invention in fiber form is one which has 60-80%, based on the total weight of the cellulose graft mixed polymer, of grafted polymer side chains, 20-70% of ionic monomer units and 1-60% of the polymer side chains. of non-ionic monomer units, in each case based on the total weight of the cellulose graft copolymer.

Those cellulose graft copolymers which contain wood pulp as the basic cellulose structure are particularly preferred. The following products are particularly preferred: 30 A cellulose graft copolymer in fiber form which contains wood pulp as cellulose and which comprises 37-42%, based on the total weight of the cellulose graft copolymer, of monomer units of the formula

35

-ch2-ch -

COONa

40

and from 20-25%, based on the total weight of the cellulose graft copolymer, of monomer units of the formula

CH,

i 3

-CH0 - C-

ÎQ0CH-

45

The total amount of grafted polymer composed of ionic and non-ionic monomer units makes up 57-67%, based on the total weight of the cellulose graft copolymer.

50 Another preferred cellulose graft copolymer in fiber form is one which contains wood pulp as cellulose and in which 28-33%, based on the total weight of the cellulose graft copolymer, ionic units of the formula 55 -CH2CH -

COONa are present, and 47-52%, based on the total weight of the cellulose graft copolymer, non-ionic units of the formula

-CH2 - CH -

C00C2H5

65 are present, the total amount of grafted polymer chains composed of nonionic and ionic units being 75-85%. based on the total weight of the cellulose graft copolymer.

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Furthermore, the present invention relates to a process for producing the cellulose graft copolymer according to the invention in fiber form, which is characterized in that. that an olefinically unsaturated monomer which can be grafted onto cellulose by double bond opening polymerization and which can be hydrolyzed to ionic monomer units after the polymerization and a nonionic monomer which can be grafted onto cellulose by double bond opening polymerization are grafted onto the cellulose fibers to form a cellulose grafted mixture Receives polymer side chains, and this undergoes hydrolysis, whereby the monomer units derived from the hydrolyzable monomer are converted into ionic monomer units, while the monomer units derived from the non-ionic monomer are not, or at most partially, hydrolyzed to ionic monomer units, and wherein such hydrolysis conditions are carried out and the cellulose and the monomer materials are used in such quantities in the starting material that a cellulose graft copolymer is obtained in which 10, 5 to 90% of the total weight of the cellulose graft copolymer are grafted-on side chains of polymer residues in which 10-SO% of the total weight of the cellulose graft polymer consist of ionic monomer units and 0.5 to 60% of the total weight of the cellulose graft polymer unit consist of non-ion.

Another object of the present invention is the use of the cellulose graft copolymers according to the invention in fiber form as a component of an absorbent material.

With this use, the cellulose fibers can be used together with untreated cellulose fibers to produce an absorbent dressing material or a tampon. In this use, too, those cellulose graft copolymers defined above are particularly preferred which contain wood pulp as cellulose and contain sodium polyacrylate residues as lateral ionic polymer residues and polymethyl methacrylate residues or polymethylacrylate residues as lateral non-ionic polymer residues in the specified proportions.

The cellulose graft copolymers in fiber form according to the invention not only have highly water-absorbing properties, so that they are suitable for producing a large number of products which absorb water and aqueous liquid materials, but they are generally also a soft, non-combustible fiber material. In the cellulose graft copolymers according to the invention, as already mentioned, the grafted-on polymer residues must represent 10.5-90% by weight of the total weight of the cellulose graft copolymer, preferably forming 50-85% by weight of the cellulose graft copolymer.

These copolymer side chains ideally consist of alternating ionic and non-ionic polymer residues, but can also consist of alternating groups of ionic and non-ionic polymer residues. Certain side chains can also consist entirely of the polymer residue of one type or the other, provided that the overall ratio of ionic and nonionic residues (which will be explained in more detail below) is maintained.

Any ionic polymer residue may be present as the ionic polymer residue, such as, for example, polyacrylic acid, sodium polacrylate, polymethacrylic acid, potassium polymethacrylate, polyvinyl alcohol sulfate, polyphosphoric acid, polyvinylamine, poly- (4-vinylpvridine), hydrolyzed polyacrylonitrile and the like. These residues can contain about 10% by weight. make up to about 80% by weight of the cellulose graft copolymer, although they are preferably from about 20 to about 70% by weight of the cellulose graft copolymer.

Any non-ionic polymer residues may be present as non-ionic polymer residues, for example polymethyl methacrylate, polyethylene methacrylate, polyethyl acrylate, polybutyl acrylate, polyvinyl acetate, polystyrene, polybutadiene, polyisoprene and the like. These residues represent about 0.5 to about 60% by weight of the cellulose graft. although they preferably make up about 10 to 60% by weight of the cellulose graft copolymer.

The cellulose fibers used to produce the cellulose graft copolymer fibers according to the invention can be natural cellulose fibers, for example wood pulp (wood pulp), hemp, bagasse, cotton and the like, or regenerated cellulose fibers, such as rayon.

It is also understood that various modified cellulose fibers, such as cellulose ethers and cellulose esters, can be used, provided that these changes do not run counter to the measures aimed at according to the invention.

The cellulose graft copolymer fibers are preferably mixed using the process according to the invention by copolymerizing (a) fibrous cellulose (b) a copolymerizable monomer which can be hydrolyzed after the polymerization to form an ionic polymer residue, and (c) a copolymerizable, non-ionized at least partially non-hydrolyzable monomers. The non-hydrolyzed cellulose graft copolymer formed is treated with an excess of a strong base solution to cause hydrolysis of the hydrolyzable portions of the grafted polymer residues and to convert them to the ionic form, for example the salts of the strong base, during the nonionic, non-hydrolyzable The proportion of the grafted polymer residues remains unchanged.

It goes without saying that it is within the scope of the invention to graft either preformed copolymers or preformed homopolymers onto a fibrous cellulose skeleton to form the desired cellulose graft copolymer, although the in situ formation described above is preferred. It is also within the scope of the invention to polymerize a mixture of cellulose and the two monomers in a single reaction mixture (which is preferred), or to carry out the polymerization in stages, by first adding one monomer and then the other monomer.

The cellulose graft copolymer according to the invention is preferably produced by copolymerizing a (a) fibrous cellulose, (b) a copolymerizable monomer which can be hydrolyzed after the polymerization to form an ionic polymer residue, and (c) a copolymerizable, nonionic, at least partially non-hydrolyzable monomer. The reactants can be dispersed and the reaction can be effected in a vapor medium or a non-aqueous medium, for example in acetone, an alcohol (for example methanol, ethanol, isopropanol, etc.), benzene, liquid ammonia and the like. However, the reaction is preferably carried out in an aqueous medium.

When working in a liquid medium, it is desirable to add a few drops of an emulsifying agent to the reaction mixture in order to promote the dispersion and thus to promote a uniform copolymerization of some monomers (for example butadiene). Examples of such emulsifiers are acrylic alkyl polyether alcohols, sulfonates and sulfates (Triton X-100® from Röhm and Haas); Sodium lauryl sulfate; Lauryltrimethylammonium chloride; cationic quaternary ammonium salts of alkyltrimethylammonium chlorides and dialkyldimethylammonium chlorides, the

4th

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

contain on average 90% dodecyl groups, 9% tetradecyl groups and 19% octadecyl groups in the alkyl part, and are sold in the form of a solution containing 33% of the active ingredient, 17% sodium chloride and 50% water (Arquad 12 from Armor and Company) ; Lauryl pyridinium chloride and the like

The mixed polymerization reaction can be initiated with an ionic initiator (e.g. an alkali hydroxide), a cationic initiator (e.g. a Lewis acid such as boron trifluoride) or with radiation (ultraviolet rays, gamma rays or X-rays). The polymerization is preferably carried out according to a free radical mixed polymerization mechanism using free radical initiators, such as, for example, cerium (IV) ions, iron (II) ions, cobalt (III) ions, (NH4) 2S208, copper (I) ions and the like. The cerium (IV) ion initiator is preferred.

Since most free radical reactions are inhibited by the presence of oxygen, it is desirable to purge substantially all of the oxygen from the reaction mixture and reaction vessels by using a non-oxidizing gas such as nitrogen before adding the free radical initiator , Helium, argon, etc. through the system.

The pH range used in the reaction depends on the particular initiator used. Depending on the particular initiator, one can use any pH from a strongly acidic pH (pH 0.8 to 2.3) to a strongly basic pH (pH 12 to 14). For the preferred cerium (IV) ion initiator, the pH should be acidic, i.e. less than 7 and preferably about 0.8 to about 2.3.

The temperature to be used in the mixed polymerization reaction can vary between room temperature. H. 20 to 30 ° C) to the normal boiling point of the lowest boiling component of the mixture. If the reaction is carried out under superatmospheric pressure, the temperature can be raised above the boiling point of the lowest boiling component of the mixture. If desired, the mixture can also be cooled below room temperature. The hydrolyzable polymer residues of the cellulose graft copolymer fibers formed are hydrolyzed by reacting the fibers, preferably under reflux, with an excess of a solution of a strong base, for example sodium hydroxide, potassium hydroxide, lithium hydroxide or a base of a similar type. The concentration of this solution can be about 1 to about 50% by weight, while the hydrolysis temperature can range from room temperature to the reflux temperature.

A preferred method for producing the cellulose graft copolymer fibers according to the invention is as follows:

According to the method by E. Schwab et al. described [Tappi, 45 (1962) page 390] procedure is prepared by dissolving the cerium (IV) salt in 100 ml of a cerium (IV) ammonium nitrate initiator solution in nitric acid. Then pulp is dispersed in water and nitrogen is introduced into the dispersion with stirring. Then, while continuously introducing nitrogen gas, a small amount of the initiator solution is added to the desired dispersion and then a mixture of the hydrolyzable and non-hydrolyzable monomers described above is added. The monomers are usually added in a total weight which is at least four times the weight of the existing wood pulp (wood pulp). After the reaction has proceeded for the desired period of time (which is generally about 1 to about 5 hours), the cellulose graft copolymer fibers formed are washed, hydrolyzed in the manner described above, washed again and dried.

The preferred ionic polymer residue is sodium polyacrylate, while polymethyl methacrylate, polyethyl acrylate and

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Polybutadiene represent preferred nonionic polymer residues.

Earlier studies have shown that the use of acrylic acid as the hydrolyzable starting monomer for the introduction of the preferred ionic polymer residue leads to a considerable homopolymerization of the hydrolyzable monomer instead of to a graft copolymerization of both the hydrolyzable and the non-hydrolyzable monomers on the cellulose skeleton. Therefore, other hydrolyzable acrylic monomers were investigated, which led to the discovery that acrylonitrile is used as the hydrolyzable starting monomer for the introduction of the preferred ionic polymer residue. The non-hydrolyzable monomers used are of course only the monomers which give the nonionic polymer residues, i.e. H. Methyl methacrylate, ethyl acrylate and butadiene.

After the mixed polymerization reaction has ended, the hydrolysis of the polyacrylonitrile residues described above gives the ionic “alkali metal polyacrylate” residues,

The cellulose graft copolymer fibers according to the invention have a substantially greater absorption capacity (which is about a factor of 4 to about 9 greater) than the unmodified wood pulp (wood pulp), although the material retains a fiber shape. Furthermore, the cellulose graft copolymer fibers according to the invention are not subject to the embrittlement and cornification which occur in the cellulose fibers modified in a conventional manner.

Another unexpected, useful property of the hydrolyzed cellulose graft copolymer fibers according to the invention is the fact that they are non-flammable, while the unmodified cellulose fibers are highly flammable. The absorbent materials produced from the fibers according to the invention can therefore advantageously be used wherever sharp fire protection measures have to be taken, for example in hospitals, kindergartens, etc.

The cellulose graft copolymer fibers according to the invention can be used as such or in the form of mixtures with unmodified cellulose fibers or other absorbent materials for the production of absorbent diapers, tampons, sponges and the like. The fibers according to the invention can also be processed into nonwovens which are suitable for producing absorbent diapers, tampons, sponges and the like.

The following examples serve to further explain the cellulose graft copolymer according to the invention and its preparation.

example 1

A cerium (IV) ammonium nitrate initiator solution with a concentration of 10 mmol per 100 ml is prepared by dissolving a cerium (IV) salt in nitric acid. Then a three-necked flask equipped with a stirrer, a gas inlet tube and a dropping funnel is charged with 500 ml of water and 5 g of pulp (wood pulp). The pulp is dispersed in the water with stirring and dry nitrogen is passed through the dispersion with constant stirring for 15 minutes. 12.5 ml of the cerium (IV) ammonium nitrate initiator solution are added to the stirred dispersion while continuously introducing nitrogen. A mixture of 5.5 g of methyl methacrylate and 15.0 g of acrylonitrile is then added to the stirred suspension and the whole is left to react at room temperature for 1 hour. After one hour, the non-hydrolyzed cellulose graft copolymer fibers formed are transferred to a Buchner funnel and washed well with water and acetone. The washed fibers are then heated to reflux with excess 6% sodium hydroxide solution for half an hour

5

5

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15

20th

25th

30th

35

40

45

50

55

60

65

629 228

to hydrolyze the hydrolyzable polymer residues. The hydrolysed cellulose graft copolymer fibers obtained are washed well with water, pressed to remove the excess water and dried in an oven at 100 ° C. to form a cellulose cardboard. The composition of the product obtained is given in Table I below (Sample No. 5).

Example 2

The measures of Example 1 are repeated with the difference that varying amounts of methyl methacrylate and acrylonitrile are used. The amounts of methyl methacrylate and acrylonitrile used and the composition of the products obtained are also listed in Table I below.

Example 3

The procedure of Example 2 is repeated, with the difference that ethyl acrylate is used instead of methyl methacrylate. The amounts of ethyl acrylate and acrylonitrile used and the compositions of the products obtained are summarized in Table II below.

Example 4

The pulp boards of Examples 1, 2 and 3 are torn into pulp fluff and this is processed into absorbent pillows. For comparison purposes, a pillow is also made from unmodified pulp. The pillows are being applied

10th

of the test device described in more detail in Textile Res. Journal 37 (1967), pages 356-366 (porous plate testing apparatus) for their liquid retention capacity. In short, this test consists of placing the test pad in a Buchner funnel-type device with a porous base plate and fixing the sample in place using a standard weight that exerts a standardized compression pressure. The porous plate is then brought into contact with a liquid reservoir and the sample is allowed to absorb liquid through the porous plate until saturation. By maintaining the sample substantially at the level of the reservoir, the absorbed liquid is kept at a pressure corresponding to 0 mm liquid column with respect to the reservoir. To determine fluid retention, the saturated sample is raised with respect to the fluid reservoir, thereby applying hydraulic pressure to the absorbed fluid, which pressure is arbitrarily assumed with a 91.4 cm (34 inch) column of fluid. The device is provided with a device with which the volume of the liquid retained at the pressure of this liquid column can be determined. The retention values are expressed as the retention volume per unit weight of the absorbent fiber. The values obtained are given in Tables III and IV below under the heading “Retention values in a non-compressed state”. The liquid used in these tests is a 1% by weight aqueous sodium chloride solution, which comes very close to the absorption properties of the menstrual fluid.

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Table I

Chemical composition of cellulose-sodium-poly (acrylate-methyl methacrylate) copolymers

Grafted Reaction Tubes Sample No. Weight Pieces

Product composition (%)

not hydrolyzed

Molecular ratio hydrolyzed

Zellu

MMA

AT

cellulose

total

MMA

AT

cellulose

total

MMA

Sodium acrylate

Glucose

MMA

sodium

loose

polymer

polymer

cinemas

acrylate

1

1

4.7

0

41.5

58.5

58.1

0

41.7

58.3

58.3

0

l

2.2

0

2nd

1

2.3

2.1

41.9

58.1

45.9

12.2

38.3

61.7

42.0

19.7

l

1.8

0.9

3rd

1

1.9

2.4

42.6

57.4

41.5

15.9

37.9

62.1

37.0

25.1

l

1.6

1.2

4th

1

1.5

2.7

45.3

54.7

29.3

25.4

37.9

62.1

24.5

37.6

l

1.0

1.7

5

1

1.1

3.0

45.8

54.2

26.9

27.3

37.8

62.2

22.2

39.9

i

1.0

1.9

6

1

0.7

3.3

43.4

56.6

27.3

29.3

35.4

64.6

22.3

42.3

l

1.0

2.0

7

1

0.6

3.5

46.4

53.6

6.7

46.9

34.1

65.9

4.9

61.0

l

0.2

3.0 •

8th

1

0.5

3.6

44.4

55.6

1.4

54.2

31.3

68.7

0.99

67.7

l

0.1

3.8

9

1

0.4

3.7

45.5

54.5

0

55.5

31.6

68.4

0

68.4

l

0

3.6

10th

1

0

4.0

45.8

54.2

0

54.2

31.7

66.3

0

66.3

l

0

3.6

Cellulose = cellulose residue; MMA = polymethyl methacrylate residue; AN = polyacrylonitrile residue; NA acrylate = sodium polyacrylate residue

Table!!

Chemical composition of cellulose-sodium-poly (acrylate-ethyl acrylate) mixed polymer

Product composition (%) molecular ratio

Grafted reaction sample sample no. Weight portion non-hydrolyzed hydrolyzed hydrolyzed

Zellu

EA

AT

cellulose

Total

EA

AT

cellulose

Total

EA

Sodium acrylate

Glucosc

EA

sodium

loose ■ '

polymc risat

polymc risat

cinemas

acrylate.

1

1 '

4.5

0

20.7

79.3

79.3

0

20.7

79.3

79.3

0

l

6.1

0

2nd

1 ö

3.6

0.8

22.4

77.5

63.5

14.1

20.2

79.8

57.3

22.5

l

4.6

2.0

3rd

1 .

2.9

1.4

23.4

76.6

56.7

19.9

20.3

79.7

49.2

30.5

l

4.1

2.7

4th

1 ;

2.3

2.0

24.8

75.2

42.5

32.7

19.8

80.2

33.9

46.3

l

2.9

4.1

5

1

1.6

2.5

28.9

71.1

34.9

36.2

22.6

77.4

27.3

50.1

l

2.0

3.8

6

1

1.1

3.0

32.0

68.0

25.6

42.4

24.1

75.9

19.3

56.6

l

1.3

4.0

7

1

0.7

3.4

43.5

56.5

16.3

40.2

33.2

66.8

12.4

54.3

l

0.6

2.8

8th

1

0

4.0

48.1

51.9

0

51.9

34.4

65.6

0

65.6

l

0

3.3

Cellulose = residual cellulose; AN - polyacrylonitrile residue; -EAr ^ rPolyätkylacrylatrest; Na acrylate = sodium polyacrylate residue

7,629,228

Example 5 Tables III and IV as tamponsin

The materials of Examples 1, 2 and 3 are fluffed into pulp volume units of absorbed liquid per unit weight of fluff and given with an equal amount of non-tampon.

modified pulp fluff united. The fluff mixture is shown in the following Tables III and IV that the cellulose sample (1) grafted to a density of 0.4 s, the grafted cylindrical tampons, which are only nonionic polymer g / ccm ', a diameter of about 1.45 cm (0.57 inches) and saturated residues of methyl methacrylate (see MMA deformed into an axial length of approximately 4.27 cm (1.68 inches). Then Tables III and EA in Table IV) an absorption capacity becomes the capacity of these tampons when absorbing, which, compared to the wood pulp sample, shows only a slight 1% by weight aqueous sodium chloride solution with simual differences. In this context, determined conditions of use are determined by keeping an io that the end of the tampon made up of methyl methacrylate and ethyl acrylate is immersed in the solution for 20 minutes, grafted residues generally non-ionically and thus hydro-while the side of the tampon is a pressure of 61 phobes, but has been subjected to hydrolysis, whereby 24 inches of water is exerted by inserting the tampons into the surface properties of the grafted fibers and in particular a hydraulically inflated polyethylene sheath. The particular liquid which has been grafted with methyl acrylate is drained of excess liquid which is drained from the tampon which has been formed, thereby decreasing the difference in absorption pressure and explaining the weight of the tampon shafts in relation to pulp.

absorbed water is determined and is in the following

Table III

Physical properties of cellulose-sodium-poly (acrylate-methyl methacrylate) copolymers

Product composition {7c) Absorbance (ccmVg)

Grafted Sample No. Cellulose MMA Sodium Acrylate Liquid Kit Retention Tampon Capacity (50% igc

Mixture with pulp)

Wood pulp

100

-

1.5

2.6

1

41.7

58.3

0

0

3.08

2nd

38.3

42.0

19.7

0.8

3.49

3rd

37.9

37.0

25.1

1.5

3.81

4th

37.9

24.5

37.6

5.3

5.01

5

37.8

22.2

39.9

7.0

5.37

6

35.4

22.3

42.3

6.9

5.27

7

34.1

4.9

61.0

5.4

4.96

8th

31.3

1.0

67.7

4.2

4.40

9

31.6

0

68.4

gelled

-

10th

31.7

0

66.3

gelled

-

Table IV

Physical properties of cellulose-sodium-poly (acrylate-methyl methacrylate) copolymers

Product composition (%) Absorbance (ccm-Vg)

Grafted Sample No. Cellulose EA Sodium Acrylate Liquid Kit Retention Tampon Capacity (50% igc

Mixture with pulp)

Wood pulp

100

_

_

1.5

2.7

1

20.7

79.3

0

2.9

3.45

2nd

20.2

57.3

22.5

12.0

6.27

3rd

20.3

49.2

30.5

14.0

6.54

4th

19.8

33.9

46.3

9.5

_

5

22.6

27.3

50.1

9.3

5.29

6

24.1

19.3

56.6

9.5

5.81

7

33.2

12.4

54.3

10.8

5.92

8th

34.4

0

65.6

gelled

-

In the other extreme case, those with only one ionic, the ionic and the non-ionic polymer residues, are

Polymer grafted samples (see sodium acrylate go through a maximum in the 55 absorption properties.

Tables III and IV) reported as gelled, i.e. H. it is at

On the outside of the examined absorbent sample, a gelil example 6

The further absorption of the liquid in the The products of Examples 1, 2 and 3 are considered

Prevented central area of the sample. In contrast to these, their ability to examine their fiber properties at a

It can also be seen that the samples which retain the mechanical processing according to the invention consist of the appropriate combination of grafted onto the cellulose scaffold using a Weber-Hammer mill using ionic and non-ionic polymer residues , a 0.64 mm (1A inch) sieve ground to a pulp fluff,

a sudden increase in their absorption properties, iei- The knot content of the fluff formed is determined with the help of the genes, both in relation to the fluid retention air blowing technique. In this technique, a 5 g sample is placed on the bottom of a 1000 ml burette with absorbent pillows not compressed, as well as 65 of the fluff, after which, based on the absorption capacity of compressed fiber, air with a constant flow rate of 99

bodies, like tampons. It can also be seen that within 1 / min (3.5 eubie feet per minute) flows in via the lower tap.

omits the preferred ranges of composition to achieve swirling of the sample. Here-

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This ensures that the isolated fibers of the sample escape through the upper open end of the burette, while the heavy knots or lumps remain on the floor. The knots are then removed and weighed, and the knot content (expressed as the weight percentage of the sample) is determined. These results are shown in Tables V and VI. In addition, samples of the fibrous fluff are examined and the mean arithmetic fiber length is determined microscopically. For this purpose, the fibers are placed on a slide and covered with a cover slip. A microphotograph with a magnification of 53 times is then taken and the length of each fiber photographed is determined. Then the arithmetic mean of the fiber length is calculated, which is given in Tables V and VI.

Table V

Cornification properties of the grafted fibers 1. Cellulose sodium poly (acrylate methyl methacrylate

Product composition (%) Dry fiber (grind on a Weber mill)

Grafted Sample Cellulose MMA Sodium Acrylate Physical Form Estimated Knot Estimated Arithmetic Mit-

No content of the fiber length of each

Fibers (mm)

cellulose

100

-

-

fibrous

0-10

1.3

1

41.7

58.3

0

fibrous

0-10

1.2

2nd

38.3

42.0

19.7

fibrous

0-10

1.4

3rd

37.9

37.0

25.1

fibrous

0-10

0.8

4th

37.9

24.5

37.6

fibrous

0-10

0.9

5

37.8

22.2

39.9

fibrous

0-10

1.0

6

35.4

22.3

42.3

fibrous

0-10

1.0

7

34.1

4.9

61.0

fibrous

0-10

1.2

8th

31.3

1.0

67.7

fibrous (bound)

73

1.1

9

31.6

0

68.4

strongly bound fibers

81

0.7

10th

31.7

0

66.3

Strongly bound fibers

100

0.002

Table VI

Cornification properties of the grafted fibers 2. Cellulose-sodium-poly (acrylate-ethyl acrylate

Product composition (%) Dry fiber (grind on a Weber mill)

Grafted sample Cellulose EA Sodium acrylate Physical form Estimated knot- Estimated arithmetic mean-

No content of the fiber length of each

Fibers (mm)

cellulose

100

-

-

fibrous

0-10

1.3

1

20.7

79.3

0

fibrous

0-10

1.2

2nd

20.2

57.3

22.5

fibrous

0-10

1.3

3rd

20.3

49.2

30.5

fibrous

0-10

1.0

4th

19.8

33.9

46.3

fibrous

0-10

1.2

5

22.6.

27.3

50.1

fibrous

0-10

1.3

6

24.1

19.3

56.6

fibrous

0-10

1.3

7

33.2

12.4

54.3

bound fibers

70

1.4

8th

34.4

0

65.6

strongly bound fibers

90

0.02

It can be seen from Tables V and VI above that the cellulose graft copolymer keeps the same physical properties with respect to fiber length and knot content after mechanical treatment as wood pulp as long as the content of the non-ionic polymer residues within the specified range. If the amount of the non-ionic polymer residue in a fiber containing ionic polymer residue is reduced, the knot content increases dramatically, so that this ground pulp fluff is not suitable for dressing materials. Regarding the fiber length, it should be noted that the average fiber length decreases when the content of the non-ionic polymer residue is reduced to a value below the specified limit up to 65 to the value at which the material can indeed be regarded as a powder. In this condition, the material cannot be used as a replacement for cellulose fibers.

Example 7

In a three-necked flask equipped with a stirrer, a gas inlet tube and a dropping funnel, a dispersion of 5 g of pulp (wood pulp) in 500 ml of water is prepared. Dry nitrogen is then passed through the dispersion for 5 minutes. Then, while introducing nitrogen and stirring, 12.5 ml of the cerium (IV) ammonium nitrate initiator solution described in Example 1 are added together with a few drops of an emulsifier (Triton X-100). A mixture of 23 g of acrylonitrile and 2 g of liquefied butadiene is added to this stirred, nitrogen-flushed dispersion. The system is then closed off from the atmosphere and left to react for 4 hours at room temperature. At the end of this time, the cellulose graft copolymer fibers formed are transferred to a Büchner filter and washed well with water and acetone. The washed fibers are

9 629 228

Minutes with excess 1.5 N sodium hydroxide solution on. The leaf is milled to a fluff that

Boiled reflux, then washed with water and finally excellent fiber properties and an excellent one dried in a hot air oven at 60 ° C. The obtained absorption capacity.

Hydrolyzed cellulose graft copolymer fibers have a maximum barrel in the non-compressed state. Example 9

liquid capacity of 13 ccm3 liquid per g and a liquid. Samples are prepared which consist of 2 g cushions with a capacity of 8.4 ccm3 / g. The tampon capacity of compressed and uncompressed cellulose is 5.2 ccm3 / g if the material is in the form of a 50 wt to 7 the tampon with a density of 0.4 g / ccm3 was used. In the case of io correspond to table IV. In addition, other pillows are used in these tests. The liquid used in the fibers produced according to Examples 1, 2 and 3 is a 1% sodium chloride solution. prepares the above in all respects

Samples with the difference correspond to the fact that these additional example 8 samples are not hydrolyzed and a composition on-With nitrogen being introduced, stirring is carried out in a three-necked manner, which are shown in tables III and IV for samples 2 to 8 and flasks, respectively. which is equipped with a stirrer, a gas inlet tube and 2 to 7 under the heading "non-hydrolyzed product" a dropping funnel, a dispersion of 5 g is specified. Similarly, hydrolyzed and cotton (Johnson & Johnson Red Cross Brand) in 500 ml of non-hydrolyzed samples of cellulose-acrylonitrile-butadiene water for 30 minutes. For this stirred, with nitrogen graft copolymers prepared from Example 7. The sample-rinsed dispersion is added with 12.5 ml of a cerium (IV) ammonium cushion made of hydrolyzed fibers and non-hydrolyzed fibers. Nium nitrate initiator solution with a concentration of 1 mol is subjected to a flame test in which each sample contains cerium (IV). -ammonium nitrate per 1 in nitric acid. After further using a pair of tongs for 10 seconds in the hottest stirring and nitrogen blowing for 1 minute an area of a Bunsen burner flame is held. Then mixture of 12.5 ml of acrylonitrile and 12.5 ml of ethyl acrylate to which the sample is pulled out of the flame, and it becomes stirred dispersion and leaves for 1 hour at room temp- those samples which then continue to burn or smolder as burning. react temperature. The fibers formed are designated as non-combustible according to the bar and the other sample. The procedure of Example 1 washed and hydrolyzed. In any case, the results of these investigations show that the hydrolysed cellulose graft copolymers — non-hydrolysed fibers formed — are highly flammable, while the fibers that are pressed to remove the excess water are hydrolyzed fibers that are not combustible.

and to form a sheet in an oven at 100 ° C 30

M

Claims (11)

629 228 PATENT CLAIMS 1. Cellulose graft copolymer in fiber form, characterized in that it has a cellulose skeleton and grafted onto it, side chains of polymer residues which have resulted from 5 double bond opening polymerizations of olefinically unsaturated monomer molecules and which represent 10.5 to 90% of the total weight of the cellulose polymer graft polymer, the polypropylene polymer being the mixture are made up of ionic and non-ionic monomer units, io and wherein 10-80% of the total weight of the cellulose graft copolymer consists of ionic monomer units and 0.5-60% of the total weight of the cellulose graft copolymer consists of non-ionic monomer hexes. 2. Cellulose graft polymer in fiber form according to claim 15, characterized in that it contains natural cellulose as cellulose. 3. Cellulose graft copolymer in fiber form according to claim 1, characterized in that it contains regenerated cellulose as cellulose. 20th 4. cellulose graft copolymer in fiber form according to claim 1, characterized in that it has 60-80%, based on the total weight of the cellulose graft copolymer, on grafted polymer side chains, whereby 20-70% of ionic monomer units and 1-60% of non-ionic monomer units are present in the polymer side chains, in each case based on the total weight of the cellulose graft copolymer. 5. Cellulose graft copolymer in fiber form according to claim 1, characterized in that it contains 30 wood pulp as cellulose and that 37-42%, based on the total weight of the cellulose graft copolymer, from monomer units of the formula • CH2-CH -COQNa 35 and 20-25%, based on the total weight of the cellulose graft copolymer, of monomer units of the formula -ch2 - ? " CÛ0CH3 40 45 50 55 exist, the total amount of grafted polymer composed of ionic and non-ionic monomer units making up 57-67%, based on the total weight of the cellulose graft copolymer. 6. Cellulose graft copolymer in fiber form according to claim 1, characterized in that it contains cellulose as cellulose and that 28-33%, based on the total weight of the cellulose graft copolymer, ionic units of the formula -CH2-CH -COONa are present, and 47-52%, based on the total weight of the cellulose graft copolymer, non-ionic units of the formula ■ «CH COQCgHg are present, the total amount of grafted polymer chains composed of 65 non-ionic and ionic units making up 75-85%, based on the total weight of the cellulose graft copolymer. 7. A process for the production of the cellulose graft copolymer in fiber form according to claim 1, characterized in that an olefinically unsaturated monomer which can be grafted onto cellulose by double bond opening polymerization and which can be hydrolyzed to ionic monomer units after polymerization and an ionopolymerization which is non-ionopolymerizable on cellulose by double-bond opening. grafted monomer onto the cellulosic fibers to form a cellulosic graft copolymer so as to obtain a cellulosic backbone with grafted polymer side chains and subjecting it to hydrolysis, thereby converting the monomer units derived from the hydrolyzable monomer into ionic monomer units, while those from the non-ionic units Monomer units are not, or at most partially, hydrolyzed to ionic monomer units, and wherein such hydrolysis conditions are carried out and the starting material Cellulose and the monomer materials are used in such amounts that a cellulose graft copolymer is obtained in which 10.5 to 90% of the total weight of the cellulose graft copolymer are grafted-on side chains from polymer residues, in which 10-80% of the total weight of the cellulose graft and polymer monomers consist of polymeric monomers , 5 to 60% of the total weight of the cellulose graft copolymer consist of non-ionic monomer units. 8. Use of the cellulose graft copolymers in fiber form according to claim 1 as a component of an absorbent material. 9. Use according to claim 8, characterized in that the cellulose fibers are used together with untreated cellulose fibers to produce an absorbent bandage material or a tampon. 10. Use according to claim 9, characterized in that the fibers according to claim 5 are used as cellulose graft copolymer in fiber form. 11. Use according to claim 9, characterized in that the cellulose fibers according to claim 6 are used as the cellulose graft copolymer in fiber form.