DE3641893A1 - Fibre-containing polymer product of high absorbency, production thereof and use thereof - Google Patents

Abstract

Disclosed is a highly absorbent polymer product with at least partially protruding fibres. These fibres make it possible for the highly absorbent polymer product to interact with a matrix structure, stopping the polymer product becoming delocalised in the produced product. The polymer products of the invention are preferably used in hygiene articles, such as babies' diapers, sanitary protection products and diapers for adults.

Description

Polymer products with high absorbency find their Use in areas where aqueous liquids removed and bound to a solid phase. Such products are preferred for Manufacture of hygiene products with the task aqueous liquids such as blood or urine from Remove the place of origin so that the wearer of the Hygiene product not by an uncomfortable feeling of Moisture is impaired in its well-being.

There are already powdery granules of a weak ver known polymers that are used in hygiene products, which in addition to the absorbent polymer has a matrix structure that generally consists of a cellulose fabric, incorporated will. This matrix structure is also called a fluff layer called.  

It has been found that in the manufacture of the Hygiene articles a correct dosage of the absorbent Polymer product is very difficult to achieve because that Polymer product in the manufacture of hygiene articles through the forming matrix structure (fluff layer) is suctioned off again.

It has also been observed that packaging and Transport of the end products the absorbent polymer product has a strong migration or delocalization, causing the products suffer an undesirable shape deformation can or part of the absorbent polymer product is no longer available for use.

The object of the present invention was now a high to provide absorbent polymer product by which avoided the disadvantages of the known polymer products can be.

The polymer product according to the invention now has a high Absorbency and a particle structure where many small fibers in the individual polymer particles are closed, in particular the ends of the small Project fibers out of the polymer particles. Through the protruding fiber parts or fiber ends can polymer products according to the invention with the fluff layer in Interaction occur, so that during the incorporation local fixation of the individual polymer products in the matrix can be reached.

The polymer material used in the invention must in the Be able to use as much of an aqueous liquid as possible to be able to absorb. They usually do this preferably polymers based on acrylic acid / sodium acrylate polymer used. But also other poly merisate based on crosslinked polymers can be used in the context of the present invention. Examples of such polymers can be cross-linked poly  saccharides, such as carboxymethyl cellulose or Starch ether, or inorganic, porous materials such as for example, zeolite.

As a rule, the polymer material used must be a multiple its weight in water; the preferably used acrylic acid / sodium acrylate polymer can at least three times its weight Absorb water, leaving the polymer in a gel-like state transforms.

One particularly in the context of the present invention added polyacrylate product is commercially available FAVOR® SAB 922 (Stockhausen company). It assigns the following chemical data on:

Chemical basis: sodium polyacrylate Texture: white granules Grain size: 100-630 microns Bulk weight: 690 ± 30 g / l Flow behavior: free flowing Dry substance 95 ± 2% pH value: 6.0 ± 1 (0.1% gel in 0, 9% NaCl)
Storage: in dry storage
1 year

The sodium polyacrylate is a weakly cross-linked polymer based on acrylic acid / sodium acrylate and is after a special polymerization process.

How fluid intake works

The carboxyl groups contained in the polymer are First contact with water or aqueous solutions solvated. Here the carboxyls partially dissociate groups in negatively charged carboxylate ions. In the dissociated The state is accumulated along the polymer chain of equally loaded groups instead of each other  repel electrostatically. This leads to the expansion of Polymer ball. This makes it possible to add more quantities Take up water or aqueous solutions. Usually this process leads to the complete dissolution of the poly mers in the water. Since this is preferably used according to the invention But polyacrylate is a weakly cross-linked polymer, the polymer molecules remain in a few places firmly connected by chemical valences. So the absorption of water only causes the polymer to swell and not for a complete solution. It results So a gel in which water through secondary valence bonds (Hydrogen bonds) is firmly bound.

The preferred polyacrylate according to the invention is characterized by a high fluid intake with extremely high body retention liquids under pressure. It creates a dry and granular gel.

Depending on the diet, urine can have different sub punch included, with inorganic salts and urea make up the largest share.

The following model urine compositions were used for the test used with the polyacrylate used according to the invention:

1.94% urea
0.83% NaCl
0.10% Mg SO₄
0.06% CaCl₂

It was found that the used according to the invention Sodium polyacrylate about 40 ml of the model urine composition absorb and this amount of liquid even under pressure could save.

The fibers suitable in the context of the present invention must be connected to the absorbent polymer product.  In the context of the present invention, poly ethylene (PE) and polypropylene (PP) short cut fibers used. These fibers are according to known Ver drive manufactured and preferably have a length between 1 mm and 6 mm and particularly preferably between 2 mm and 4 mm on. Generally the fibers have a titer of 0.5-6 dtex, with a titer of 2-4 dtex preferred becomes. A slight deviation in the length of the individual fibers does not interfere with the use according to the invention. It can even be advantageous to target different fiber lengths use to preferred adhesive effects of the polymer to achieve product in the fluff layer.

Even if other fibers within the scope of the present invention, for example, such of natural origin, glass fibers or fibers made from various synthetic materials could be used are the PE and PP short cut fibers), preferred because of these fibers develop a molecular wicking effect, so that they move the liquid from the place of origin to the high can pass on absorbent polymer products. Ver improvement in the adhesiveness of the fibrous high-absorbency Polymer product, it may be advantageous to the fibers to undergo a special treatment by which the Structure of the fibers is changed so that it is easy are curled and thus better mechanical inter action with the fibers of the matrix structure in which the invention appropriate polymer particles are embedded to achieve. Such an additional treatment step can Stretch the fibers before cutting to length.

In principle, the products according to the invention can be produced two ways can be followed.

• a) The polymer product with high absorptive capacity is mixed with the faders and the connection is achieved by adding an adhesion promoter. The type of adhesion promoter used depends both on the type of polymer product used and on the type of fibers used. On the basis of the chemical composition of the absorbent polymer material and the fibers, the person skilled in the art can select those adhesion promoters through which a reliable connection between the two components mentioned above can be achieved. In addition, the adhesion promoters must of course not have any undesirable side effects, which depend on the type of use. If the polymer products are to be used, for example, in hygiene articles such as diapers, the adhesion promoters must be harmless to health.
  After the polymer grains have been glued to one another and to the fibers used, small to medium-sized fiber flakes are obtained which are comminuted in a hammer mill and then dried.
  The finished product then contains many small fibers in the individual particulate polymer particles, the ends of which protrude from them in particular.
  Among the large variety of known adhesion promoters, ethylene / acrylamide copolymers, polymer isocyanates or reactive silicon-organic compounds are preferred in the context of the present invention, ethylene / acrylic acid copolymers being particularly preferred.
  The addition of an adhesion promoter can be dispensed with if the dispersion of the polymer product already results in gel formation in the edge regions of the granular polymer product, and if a sufficiently firm bond between the polymer product and the fiber can already be achieved as a result.
• b) Another way of connecting the fiber material to the polymer product is that the fiber material is added to the polymer solution before the polymer material is finished and that the crosslinking reaction then takes place. The fibers are at least partially enclosed in the polymer product, so that there is a connection of the fiber ends with the interior of the polymer product. With such a manufacturing method, a product can be achieved with the ends of the fibers inside the polymer, thereby achieving a faster and more effective transfer of the liquid to be removed into the polymer, since the fibers, as already mentioned, have a wicking effect.
  With this type of production, an oil-in-water polymerization can be carried out.

The ratio of the fibers used to the highly absorbent Polymer product can be changed in relatively wide ranges will. A weight ratio of is preferred Fibers to highly absorbent polymer product from 1: 1 to 1:10. In this way, product variations can be won, from a more cotton-like, flaky to one essentially granular polymer product can suffice.

Through the fiber-containing polymer products according to the invention With high absorbency, the production of End products, especially when it comes to hygiene products acts, significantly relieved.

Due to the structure according to the invention, the fiction contemporary polymer products in the manufacture of hygiene products can be dosed in a targeted manner, as they are effective Interaction of the product according to the invention with the Matrix of the hygiene product takes place. An unwanted one The absorbent material falls out or is sucked through Polymer product from or through the finished product can thus be prevented by the structure of the new product. So since the material used is almost completely in  the finished material remains, the dosage ent can be adjusted accordingly and thus undesirable Losses are avoided.

The finished hygiene product must be put in place at the end valid use, various transport and Go through storage phases. Of course, the shape should and do not change the composition of the finished product. Precisely because of the structure of the fibrous material according to the invention Polymer product with high absorbency can a relatively firm connection of the polymer product with the other component of the hygiene product, namely the Matrix structure can be achieved.

Due to the wicking of the preferred fibers the area of each polymer particle is enlarged, who can actively absorb the aqueous liquid. If namely the polymer particles without the corresponding fibers are used, so arise between the individual Particles cavities and droplets therein that are not one of the particles can come into contact. Invention however, the use of fibers makes it dense network made up of individual fibers, reducing the size of the gaps between each Particles can be reduced. Compared to the Known polymer products without fibers can be a more effective one and faster suction through the inventive fiber-containing polymer products can be achieved.

From a medical point of view, the inventive Products have an advantage over the known products on. Because of the easy mobility of the fiberless Polymer products can do this not only during storage or escape transport from the finished product, but also when used on the human body these polymer products can emerge from the hygiene product and then with the human skin or the sensitive one Mucous membranes come into contact and irritation or  cause immunological irritation. The Products according to the invention, however, are firm with the fluff layer of the hygiene product and can therefore not in direct contact with human skin reach.

The polymer products according to the invention can also be anti microbially active substances, such as fungicidal acting substances are added to thereby create a Fungal infestation, which is particularly serious in infants Prevent problem.

The polymer products according to the invention are preferred for used in the manufacture of hygiene products. It deals preferred hygiene diapers for baby products, Sanitary towels, panty liners and diapers for adults.

Another possible use of the invention Polymer products is in the process of removing water hydrophobic liquids possible. The fibrous ones High absorbency polymer products in one Filter matrix embedded and the water to be filtered contains hydrophobic liquid through the filter system headed. The hydrophobic liquids can be organic solvents or fuels for example, kerosene, diesel oil or hydraulic oil.

Embodiments Raw materials

Highly absorbent polymer product (brand Fabor SAB 922); powdered sodium polyacrylate with a grain size of 100-630 microns.

Polyethylene (PE) and polypropylene (PP) fibers (Steen) with a titer of 2.0 or 2.8 dtex and a cutting length of 2 mm.  

Adhesion promoter: dispersion solution (Primacor 4983 from Dow Chemical) containing 25% ethylene / Acrylic acid copolymer. Dilution: 20 ml of the 25% Dispersion with dist. Dilute water to 100 ml.

Test execution example 1

3 g PE fiber (2.8 dtex, 2 mm cutting length) and 6 g polymer powder was placed in a 250 ml beaker, 6.8 g of diluted dispersion solution added and immediately through vigorous stirring with a glass rod mixed well. By Bonding the polymer grains to each other and to the fibers small to medium-sized fiber flakes were obtained, which were then crushed in a hammer mill (ground for approx. 30-60 sec.).

After drying the product at a slightly elevated temperature (50-60 ° C) a soft, flaky product was obtained.

Example 2

2.0 g PE fiber (titer 2.8 dtex, cutting length 2 mm) 6 g Polymer powder and 4.7 g of the diluted dispersion were processed as described in Example 1.

Result: loose, flaky, more granular product.

Example 3

0.5 g of viscose fine cut (cellulose fluff) was mixed with 2.5 g PP fibers (titer 2.0 dtex, cutting length 2 mm) mixed well, then 6 g of polymer powder and 8 g of the dilute dis persion added and as described in Example 1 processed.

Result: very soft, flaky product with predominantly fine-grained structure of the polymer particles.

Claims (19)

1. Polymer product which can absorb and retain at least three times its weight in aqueous liquid, characterized in that the poly mer product has fibers which at least partially protrude from the polymer product. 2. Polymer product according to claim 1, characterized in that that the polymer at least 30 ml of aqueous liquid per g can absorb and retain polymer product. 3. Polymer product according to one of the preceding claims, characterized in that the polymer material Is acrylic acid / sodium acrylate polymer. 4. Polymer product according to one of the preceding claims, characterized in that the fiber is short polyethylene are cut fibers. 5. Polymer product according to one of claims 1 to 3, characterized characterized in that the fiber polypropylene short cut fibers are. 6. Polymer product according to one of the preceding claims, characterized in that the polymer product also an adhesion promoter to connect the polymer product and having fibers. 7. Polymer product according to claim 6, characterized in that that the coupling agent is an ethylene / acrylic acid copolymer is. 8. Polymer product according to one of the preceding claims, characterized in that the polymer product without Fibers have a particle size between 100 and 630 microns  having. 9. Polymer product according to one of the preceding claims, characterized in that the weight ratio of Fibers to polymer product between 1: 1 and 1:10 be wearing. 10. A method for producing a polymer product according to any one of the preceding claims, characterized in that

• a) a polymer product of the desired particle size is produced,
• b) the fibers are bound to the particulate polymer product with the aid of an adhesion promoter and
• c) the fiber flakes obtained are ground to the desired particle size.

11. The method according to claim 10, characterized in that the coupling agent is an ethylene / acrylic acid copolymer is. 12. A method for producing a polymer product one of claims 1 to 9, characterized in that that the fiber material before the crosslinking reaction of the Polymer solution is added and that then the Crosslinking reaction is initiated. 13. The method according to claim 12, characterized in that the polymerization reaction is an oil-in Water polymerization is concerned. 14. Use of the fiber-containing, highly absorbent polymer product according to one of claims 1 to 9 in hygiene products. 15. Use according to claim 14, characterized in that that the hygiene products are baby diapers acts.   16. Use according to claim 14, characterized in that that these are products for the female genital area acts. 17. Use according to claim 14, characterized in that that they are adult diapers. 18. Use of a polymer product according to one of the An sayings 1 to 9 for the separation of aqueous components from hydrophobic liquids. 19. Use according to claim 18, characterized in that that the hydrophobic liquids are organic solvents and / or hydrocarbons.