CS268621B1 - Non-woven area with high water sorption - Google Patents

Abstract

The subject of the solution is a nonwoven sheet with high sorption of water, aqueous solutions and physiological fluids, which is produced by impregnating a nonwoven or nonwoven textile with a water-dilutable thermoreactive system based on dispersion acrylate copolymers, at least one of which contains a high number of carboxyl groups, followed by neutralization with an aqueous solution of alkali metal hydroxide and heat treatment. Finally, it is possible to adjust the final appearance and compactness of the surface by calendering.

Description

The present invention relates to a nonwoven sheet with high sorption of water, aqueous solutions and physiological fluids, which is produced by impregnating a nonwoven or nonwoven fabric with a water-dilutable thermoreactive system based on dispersed acrylate copolymers, at least one of which contains a high number of carboxyl groups, followed by neutralization with aqueous hydroxide solution. alkali metal and heat treatment.

Previously known sheets with the ability to sorb high volumes of water and physiological fluids are based on the application of powdered superabsorbents prepared by known methods, for example EUR PAT. APP1. 68,189, EUR. PAT. APPL. 36 463, GER. OFFEN 302 6043, JPN 81 33 032, JPN 85 255 814 and others. These are partially crosslinked copolymers based on acrylic or methacrylic acid in the form of their sodium salts.

Another numerous group consists of powder superabsorbents based on modified polysaccharide compounds, such as starches, cellulose derivatives and the like. Their preparation and composition is protected, for example, by JPN 81 70 Oil, JPN 81 114 889, JPN 82 133 142, JPN 83 183 754, JPN 85 67 127 and others.

These powdered polymers are also used to produce sheets with high absorbency for water and saline solutions. These are mostly so-called Tea bagg "systems, where the powder superabsorbent is sprinkled resp. thermally bonded between cover layers of flat non-woven material or paper. (JPN 80 148 154, JPN 8 102 163, BELG 886 001 and others). In addition to the complexity of the preparation, which requires special application and dosing machinery after the production of the polymer powder form, the limited cohesion of the superabsorbent heterogeneous particles with the supporting or covering surfaces is also disadvantageous.

From the point of view of the amount required to achieve a high retention of aqueous solutions or physiological fluids, the process of direct application of the polyacrylate copolymer dispersion in neutralized form is also disadvantageous. -An obstacle to achieving the required application is the high viscosity of the neutralized paste. In order to achieve higher values of water retention, the entire application and drying process may have to be repeated several times, which is technologically complicated and unbearable in terms of capacity. Multiple application of dispersion paste copolymers has a negative effect on the stiffness of the sheet.

The sheet of high water and physiological fluid retention which is the subject of the invention is characterized by a high compactness of a carrier fibrous or nonwoven medium with a polymeric, water-dilutable system (I) based on at least 5% by weight of copolymers containing 50 to 80% acrylic acid ester and / or methacrylic, 20 to 50% of these acids, polyols containing at least two hydroxyl groups in the molecule, and / or divinylbenzene. This aqueous dispersion system is applied to a fabric web, but is preferably used in particular for a web intended for the production of nonwoven webs by conventional methods used in the production of nonwovens or sheets with a coating or coating, such as an aqueous solution spray. foam and flaking. Sheets with the required mechanical resistance can be finished on a fulard or an effective superabsorbent layer in the form of a paste can be applied to them by coating, resp. coating. After that, the formation is freed of excess water and neutralized with an aqueous alkali metal hydroxide solution having a concentration of 2 to 15% by weight and heat-treated at a temperature of 120 to 200 ° C.

To control the mechanical-physical properties of the superabsorbent sheet thus produced, a mixture of the above-mentioned dispersible water-dilutable system (I) with a dispersed acrylate copolymer (II) with a glass transition temperature (Tg) of less than -10 ° C is preferably applied. Furthermore, the addition of this copolymer does not affect the superabsorbent properties of the product, obtained by applying the active component (I) itself, but significantly reduces in particular the stiffness and brittleness of the sheet.

The sheet according to the invention has a high ability to sorb aqueous solutions. Its absorbency is at least 1500% by weight, which is at least 15 g of water per 1 g of substrate. Preferably, the water-dilutable polymer dispersion system is also used as a water-soluble dispersion polymer system

CS 268621 Bl fleece binder in the production of nonwoven nonwoven textile sheets, where the mechanical strength of this structure in dry form reaches values comparable to products bonded with conventional thermoreactive dispersion systems, i.e. at least 120 N at an elongation of at least 10%. During application, there are no problems with the viscosity of the dispersion system, resulting from the enormous increase in viscosity after its neutralization, and the distribution of the starting form of the aqueous polymer active system is perfect in the cross section of the sheet. A single application of the aqueous dispersion system, which is only then neutralized, is sufficient to achieve the required properties of the sheet. Due to the compact penetration of the effective copolymer composition, intensive swelling of the sheet occurs in contact with water, aqueous or physiological solutions. The homogeneity of the surface of the sheet, which is at least five times its original thickness, can be further increased by calendering at elevated temperatures. The product in question with high superabsorbent properties can be used with regard to its mechanical and physical properties in the field of technical textiles, in particular as a water-blocking, self-sealing insert for the production of cables, geotextiles and hygienic medical products.

The production of superabsorbent sheets is ensured without complicated production and finalization of powdered superabsorbents, which require special drying and granulation equipment and increase the energy intensity compared to the possibility of direct application of the starting water-dilutable composition (I). The advantages of the product include the fact that it can be produced from common raw materials available in the country on machinery common in the technology of production of nonwovens or treatment and coating of flat textile structures.

Examples of a specific embodiment of the invention

The subject fleece sheet with high water sorption and its production is documented in the following examples. '

For its production, alternative variants of the composition of aqueous dispersions of copolymers I with a high content of carboxyl groups Aj to Gj with a dry matter of 25 to 60% by weight, used in Table 1, were used:

composition of copolymers (% by weight) ^A i ^B i ^C I ^D i ^E T ^F i G_ 1 acrylic acid 17.5 30 28 10 20 methacrylic acid 17.5 - 35.7 - 25 50 - e tylacryla t 63 60 64 65 63 - 76 butyl acrylate - 7 - - - 43 - pentaerythritol triacrylate 2 - 0.3 - 0.5 2 - trimethylolpropane triacrylate - 3 - - - - - ethylene glycol dimethacrylate - - - 7 1.5 - - butanediolacrylate - - - - - 5 - divinylbenzene - - - - - - 4

Equally good results are obtained if esters with polyols containing 2 to 6 carbon atoms are used instead of the above-mentioned polyol esters.

□ alternatively aqueous dispersions of copolymers A 2 were used as polymer dispersions for the control of mechanical-physical properties, in particular stiffness and brittleness of the subject sheet; is stated, also up to G _IT their with a dry matter of 25 to 60% by weight, listed in the table number glass temperature < ^T 9

CS 268621 Bl

composition of copolymers (% by weight) ^A II ^B II ^C II ^E II ^F II ^G H acrylic acid 2 2 - - 1 2 - methacrylic acid - 1 - - - - butyl acrylate 68 55 - - - - - 2-ethylhexyl acrylate - - 80 - - 50 - ethyl acrylate 30 43 - - - 48 - styrene - - 19 30 34 - - butadiene - - - 70 65 - 68 acrylonitrile - - - - - 32 T (° C) c ^{K 1} -45 -40 -30 -30 -20 -45 -35

The percentages given in the examples are always by weight.

Example 1 A non-woven sheet of 100% Vs staple with a basis weight of 100 g.m was produced by applying a bath of the composition:

% aqueous dispersion with dry matter 25%% aqueous dispersion with dry matter 60%% water

100% spa

The bath was applied in the form of a foam - with a wet weight of 200% and dried. Then, 22 g of 10% sodium hydroxide per 1 m was applied with a flap roller, followed by drying and condensation at 145 ° C. 90 s. Finished by calendering: two-cylinder calender, metal cylinder temperature 120 ° C, pressure 10 kPa.

The fleece formation achieved the following parameters:

absorbency 1515%, tensile strength 130 N, swelling 6x, roughness 21 mN.

Material especially suitable for waterproofing cables. '

Example 2

-2 Non-woven sheet of 100% ni Vs scrap with a basis weight of 100 g.m, which was made by applying a bath of the composition:

parts by weight of aqueous dispersion with a dry matter content of 25% by weight of aqueous dispersion A ₂ with a dry matter content of 60%.

parts by weight of water

100 parts by weight of bath

The bath was applied to a 300% wet weight scar and dried. Then, 34 g of 2% sodium hydroxide per 1 m are applied to the impregnation, followed by drying and condensation at 150 ° C, 80 s.

The fleece formation achieved the following parameters:

absorbency 700%, tensile strength 110 N, swelling 3x, stiffness 26mN. The material is suitable for hygienic purposes.

Example 3

A fleece sheet with a composition of 65% Vs staple and 35% PES staple with a basis weight of 120 g.m, which was made by applying a bath with the composition:

parts by weight of an aqueous dispersion of Al 2 with a dry matter content of 25% by weight of water

100 parts by weight of bath

The bath was applied with a 100% wet spray and dried.

35 g of 4% sodium hydroxide per liter were applied to the sprayer, followed by drying and condensation at 160 DEG C., 70 s. Finished by calendering at 120 DEG C., pressure 10 kPa.

The fleece formation reached the following parameters: absorbency 700%, tensile strength 130 N, swelling 3x, stiffness 130 mN. Material especially suitable for waterproofing cables.

Example 4

Non-woven fabric with a composition of 80% Vs staple and 20% POP staple with a basis weight_9 ti 110 g. m, which was produced by applying a bath of the composition: 20 parts by weight of an aqueous dispersion with a dry matter content of 25% by weight of an aqueous dispersion of A ₂ with a dry matter content of 60% 68 parts by weight of water

100 parts by weight of bath

The bath was applied in the form of a foam with a wet weight of 200% and dried. Then 67 g of 2% sodium hydroxide per m 2 were applied to the im2 pregnancy, followed by drying and condensation at 140 ° C, 120 s. Finishing by calendering - two-roll calender, metal roll temperature 120 ° C, pressure 10 kPa.

The fleece formation achieved the following parameters:

absorbency 500%, tensile strength 130 N, swelling 4x, stiffness 20 mN. Material especially suitable for hygienic purposes.

Example 5

A nonwoven fabric with a composition of 90% Vs staple and 10% PES staple with an area weight of 2 '100 g. m, which was made by applying a bath of the composition:

parts by weight of an aqueous dispersion with a dry matter content of 25% by weight of an aqueous dispersion of A ₂ with a dry matter content of 60% by weight of water parts

100 parts by weight of bath

The bath was applied in the form of a foam with a wet weight of 250% and dried. Then, 67 g of 4% sodium hydroxide per 1 m were applied to the impregnation, followed by drying and condensation at 150 ° C, 90 s.

The fleece formation achieved the following parameters:

absorbency 1450%, tensile strength 125 N, swelling 5x, stiffness 30 mN. The material is suitable for waterproofing, but also for hygienic purposes.

Example 6

Non-woven fabric with a composition of 80% Vs staple, 10% PES staple and 10% POP staple2 with a basis weight of 100 g. m, which was made by applying a bath of the composition:

parts by weight of aqueous dispersion A 2 with a dry matter content of 25% by weight of parts of aqueous dispersion B ₂ with a dry matter content of 50% by weight

100 parts by weight of bath

The bath was applied in the form of a foam with a wet weight of 250% and dried. Then, 67 g of 4% sodium hydroxide per 1 m are applied to the impregnation, followed by drying and condensation at 150 ° C, 90 s.

The fleece formation achieved the following parameters:

absorbency 1520%, tensile strength 135 N, swelling 5x, stiffness 25 mN. The material is suitable for hygienic purposes and also for waterproofing cables.

CS 263621 31

Example 7

Non-woven fabric c composition of 30% Vs staple, 10% PES staple and 10% POP staple-2 with a basis weight of 100 g. m, which was made by applying a bath of composition;

parts by weight of aqueous dispersion C · ^ with a dry matter content of 25% by weight of aqueous dispersion F with a dry matter content of 50% by weight of water parts

100 parts by weight of bath

The bath was applied in the form of a foam with a wet weight of 200% and dried. Then 15 g of 15% sodium hydroxide per 1 m are applied by impregnation with a wading roller, followed by drying and condensation at 150 ° C, 90 s. The finishing was performed on a two-roll calender with a metal roll temperature of 120 ° C, a pressure of 10 kPa.

The fleece formation achieved the following parameters:

absorbency 1520%, tensile strength 135 N, swelling 5.x, stiffness 23 mN. The material is particularly suitable for waterproofing cables, but also for hygienic purposes.

Example 8

Non-woven fabric made of 100% Vs scrap with a basis weight of 100 g. m, which was made by applying a bath of the composition:

parts by weight of an aqueous dispersion with a dry matter of 25% · parts by weight of an aqueous dispersion of C ₂ with a dry matter of 50% by weight of water

100 parts by weight of bath

The bath was applied in the form of a foam with a wet weight of 200% and dried. Then, 22 g of 10% sodium hydroxide per 1 m was applied by 2 impregnation with a wading roller, followed by drying and condensation at 150 ° C for 90 s.

The fleece formation achieved the following parameters: absorbency 1520%, tensile strength 135 N, swelling 5x, stiffness 26 mN. The material is suitable for waterproofing cables, for hygienic purposes, but also as a special agrotextile with high water retention.

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION Nonwoven fabric based on fiber and polyacrylates with sorption of water, aqueous solutions and physiological fluids, characterized in that it can be produced by impregnating the nonwoven and / or nonwoven fabric with a water-dilutable system each containing at least 5% by weight of dispersion copolymer I consisting of 50 to 80% acid ester acrylic and / or methacrylic with 20 to 50% of acrylic and / or methacrylic acid and with 0.1 to 8% of acrylic and / or methacrylic acid ester with polyols having 2 to 6 carbon atoms containing at least two hydroxyl groups in the molecule and / or divinylbenzene and optionally containing the addition of up to 50% of dispersion copolymers II with a glass transition temperature of less than -10 ° C, followed by removing at least 30% of water from the impregnated substrate, neutralizing it with 2 to 15% aqueous alkali metal hydroxide solution and heat treatment at 120 ° C. up to 200 ° C.