METHOD OF FORMING BIODEGRAD ABFE NONWOVEN FABRIC, NONWOVEN FABRIC OBTAINED BY THIS METHOD, AND SYSTEM OF DEVICES FOR CARRYING OUT THIS METHOD

Abstract

The invention relates to a method of forming a biodegradable nonwoven fabric, the nonwoven fabric obtained by this method, and a system of devices for carrying out this method, to be used for the manufacture of cellulosic articles for clean-up work and sanitary products, and medical uses.

Claims

1. A method of forming a biodegradable nonwoven fabric containing at least 50% by weight of cellulose pulp based on dry weight of the nonwoven fabric consisting of two layers bonded by means of water needling, wherein in the said method the first layer of the nonwoven fabric is manufactured by dispersing cellulose pulp fibers in water, from which the cellulose pulp fiber layer is wet-formed, which layer is strained out, and the second layer is formed in a process of carding fibers selected from a group consisting of viscose fibers, Lyocell fibers, cotton fibers, cottonized flax fibers and cottonized hemp fibers, or any mixture thereof, to obtain the carded fiber layer, then both the cellulose pulp fiber layer and the carded fiber layer are applied onto each other in any order and are bonded in a water needling process by means of a needle loom, followed by air-drying of the obtained nonwoven fabric.

2. The method according to claim 1, wherein the wet-formed cellulose pulp fiber layer is strained out by means of a forming head.

3. The method according to claim 1, wherein the obtained nonwoven fabric is dried by means of the through-air dryer.

4. The method according to claim 1, wherein the first layer of the nonwoven fabric is manufactured from cellulose pulp obtained from scrap paper.

5. The method according to claim 4, which comprises an additional step of purifying the cellulose pulp obtained from scrap paper from mechanical impurities on screens.

6. The method according to claim 4, which comprises an additional step of purifying the cellulose pulp obtained from scrap paper form chemical impurities by a flotation process.

7. The method according to claim 1, wherein viscose fibers, including Lyocell fibers, used for forming the second layer, are obtained from regenerated wood cellulose.

8. The method according to claim 1, wherein the carded fiber layer is manufactured from unbleached cotton and/or regenerated cotton and/or cottonized flax and/or cottonized hemp, and the obtained nonwoven fabric after the water needling process is treated with bleaching substances selected from the group consisting of ozone, hydrogen peroxide, chlorine dioxide, or a mixture thereof, and optionally treated with pH adjusting agents and/or fiber softeners.

9. The method according to claim 1, wherein the carded fiber layer is manufactured from unbleached cotton and/or regenerated cotton and/or cottonized flax and/or cottonized hemp, and the obtained nonwoven fabric is reeled over a perforated tube and treated with bleaching substances selected from ozone, hydrogen peroxide and chlorine dioxide, or a mixture thereof, and optionally treated with pH adjusting agents and/or fiber softeners.

10. The method according to claim 9, wherein the nonwoven fabric a treated with bleaching substances in pressurized apparatuses.

11. The method according to claim 9, wherein the nonwoven fabric is unreeled from the perforated tube, dewatered, followed by air-drying by means of a through-air dryer.

12. The method according to claim 1, wherein the water-dispersed cellulose pulp fiber layer in the manufactured nonwoven fabric has a dry unit weight equal or greater than a unit weight of the carded fiber layer.

13. The method according to claim 1, wherein the water-dispersed cellulose pulp fiber layer is not bonded nor compressed before contacting with the carded fiber layer, and the carded fiber layer is not bonded nor compressed before contacting with the water-dispersed cellulose pulp fiber layer.

14. The method according to claim 1, wherein the water-dispersed cellulose pulp fiber layer is composed of 85-100% by weight of bleached cellulose pulp fibers, admixed with 0-15% by weight of short staple regenerated cellulose fibers, PLA, or a mixture thereof, based on dry weight of the cellulose pulp fiber layer.

15. The method according to claim 1, wherein the carded fiber layer contains an additive in a form of biodegradable bicomponent fibers in a maximum amount of up to 10% based on dry weight of the carded fiber layer.

16. The method according to claim 15, wherein the biodegradable bicomponent fibers in the carded fiber layer contain PLA.

17. The method according to claim 15, wherein the nonwoven fabric is dried with air at the temperature sufficient to partly melt the shell of the biodegradable bicomponent fibers contained in the carded fibers layer.

18. A nonwoven biodegradable fabric comprising two layers bonded by means of a water needling process, containing at least 50% by weight of cellulose pulp based on dry weight of the nonwoven fabric, comprising two layers, wherein the first one of its layers comprises a wet-formed softwood cellulose pulp and/or scrap paper fiber layer, and the second one of layers comprises a carded viscose fiber and/or Lyocell fibers and/or cotton and/or cottonized flax and/or cottonized hemp fiber layer.

19. The nonwoven fabric according to claim 18, wherein a unit weight of any of the layers is in the range between 10 g/m.sup.2 and 60 g/m.sup.2.

20. The nonwoven fabric according to claim 19, wherein a unit weight of any of the layers is in the range from 15 g/m.sup.2 to 45 g/m.sup.2.

21. The nonwoven fabric according to claim 18, wherein the wet- formed cellulose pulp fiber layer contains from 90 to 93% by weight of softwood and/or scrap paper cellulose pulp and from 7 to 10% by weight of biodegradable bicomponent fibers, a component of which is PLA, based on dry weight of the cellulose pulp fiber layer.

22. The nonwoven fabric according to claim 18, wherein the carded fiber layer contains from 90 to 93% by weight of viscose fibers and/or Lyocell fibers and/or cotton fibers and/or cottonized flax and/or cottonized hemp fibers and from 7 to 10% by weight of biodegradable bicomponent fibers, a component of which is PLA, based on dry weight of the carded fiber layer.

23. A system of devices for forming the biodegradable nonwoven fabric as defined in claim 17, which is provided in a processing line in a pulper, a head for forming a fiber layer of the water-dispersed cellulose pulp, a carding machine for forming a carded fiber layer, a needle loom for bonding fibers by means of kinetic energy of water micro- streams from the needling beam, forming curtains of the streams, tanks for the water bath for oxidizing impurities and bleaching fibers, the through-air dryer and the reeling machine.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0033] The object the invention was visualized in an embodiment in the attached figure of the drawing, wherein a scheme of a production line for the nonwoven fabric according to the invention is shown.

DETAILED DESCRIPTION OF THE INVENTION

[0034] In the method of forming the biodegradable nonwoven fabric of the invention, which contains at least 50% by weight of cellulose pulp, based on dry weight of the nonwoven fabric and consists of two layers, wherein the first layer of the nonwoven fabric is obtained by dispersing cellulose pulp fibers in water, from which cellulose pulp fiber layer 7 is wet-formed, followed by straining out by means of a forming head 1, while the second layer is formed by means of a process of carding viscose fibers and/or Lyocell (Tencel) fibers and/or cotton and/or cottonized flax and/or cottonized hemp fibers, to obtain the carded fiber layer 8. Subsequently, both layers, the cellulose pulp fiber layer 7 and the carded fiber layer 8 are applied on each other in any order and bonded in a water needling process by means of the needle loom 3, followed by air-drying of the obtained nonwoven fabric by means of the through-air dryer 5. The final product in a form of a bilayered nonwoven fabric is preferably reeled into a roll on a reeling machine 6 and/or cut. It can also be treated differently depending on the desired form.

[0035] If the dispersed cellulose pulp fibers are obtained from scrap paper, they are purified from mechanical impurities on screens and purified from chemical impurities by a flotation process. The step of purifying cellulose pulp precedes the step of forming the cellulose pulp fiber layer. The viscose fibers, Lyocell (Tencel) are preferably obtained from regenerated wood cellulose. If the carded fiber layer is made of unbleached cotton and/or regenerated cotton and/or cottonized flax and/or cottonized hemp, the nonwoven fabric, following the water needling process, is treated with bleaching substances selected from substances such as ozone, hydrogen peroxide, chlorine dioxide, and, if required, pH adjusting agents and fiber softeners. In one embodiment the nonwoven fabric is purified in pressurized apparatuses, i.e. the process for the treatment of the nonwoven fabric with bleaching substances is carried out under the elevated pressure and/or elevated temperature. A dry unit weight of the water-dispersed cellulose pulp fiber layer is at least equal to a unit weight of the carded fibers. The water-dispersed cellulose pulp fiber layer is not bonded nor compacted before contacting the carded fiber layer, and the carded fiber layer is not bonded nor compacted before contacting the water-dispersed cellulose pulp fiber layer.

[0036] In another embodiment, if the carded fiber layer is made of unbleached cotton and/or regenerated cotton and/or cottonized flax and/or cottonized hemp, the obtained nonwoven fabric is reeled over a perforated tube and treated with bleaching substances selected from ozone, hydrogen peroxide and chlorine dioxide, and, if required, pH adjusting agents and fiber softeners. The process can be also conducted in a pressurized apparatus. The nonwoven fabric is unreeled from the perforated tube and dewatered, and air-dried in turn by means of a through-air dryer.

[0037] The nonwoven biodegradable fabric according to the invention, manufactured in at least 50% by weight of cellulose pulp, based on dry weight of the nonwoven fabric, comprises the first layer of softwood and/or scrap paper cellulose pulp, and the second layer comprising viscose fibers and/or Lyocell (Tencel) fibers and/or cotton and/or cottonized flax and/or cottonized hemp fibers. A unit weight of any of the layers is in the range between 10 g/m.sup.2 and 60 g/m.sup.2, and more preferably in the range from 15 g/m.sup.2 to 45 g/m.sup.2.

[0038] A system of devices for forming the nonwoven biodegradable fabric is provided in the processing line in a pulper 10, from which cellulose pulp is passed to a head 1 for forming a fiber layer 7 of water-dispersed cellulose pulp. Over the layer formed from the cellulose pulp fibers, a carded fiber layer 8, formed in a carding machine 2, is than applied. Both layers together are passed on a needle loom 3, where they are bonded by means of a curtain of water micro-streams generated from a needling beam 9. The bonded nonwoven fabric layers are introduced into a water bath in a tank 4, where oxidation of impurities and bleaching of the nonwoven fabric is performed. After washing, the nonwoven fabric from the tank 4 is passed to the through-air dryer 5, where it is dried. From the dryer, the finished nonwoven fabric is passed to the reeling machine 6, where it is reeled into a roll.

EXAMPLE 1

[0039] A biodegradable composite nonwoven fabric is formed by assembling and water needling two layers described below. The first layer is formed in a process of carding 100% viscose (regenerated cellulose) fibers and has a basis weight of 17-20 g/m.sup.2. The second layer composed of 100% of bleached softwood cellulose pulp fibers is wet-formed in a wetlaid process on a casting-straining headbox type machine and has a basis weight of 33-37 g/m.sup.2. Both fiber layers are formed as non-bonded and non-compressed before their mutual contact. Over a fleece of the carded viscose fibers, the hydro-formed cellulose pulp fiber layer is applied, and the obtained bilayered structure is processed by water needling. The obtained nonwoven fabric is then dried, and subjected to further treatment by cutting and/or reeling. Depending on the required final form, the nonwoven fabric may be subjected to further treatment.

EXAMPLE 2

[0040] A water-needled biodegradable composite nonwoven fabric was obtained in an analogous manner to the one described in Example 1. The first layer is formed in a process of carding 100% Tencel (Lyocell) (regenerated cellulose) fibers and has a basis weight of 16-21 g/m.sup.2. The second layer composed of 100% of bleached softwood cellulose pulp fibers, is wet-formed in a wetlaid process on a casting-straining headbox type machine and has a basis weight of 32-38 g/m.sup.2. Both fiber layers are formed as non-bonded and non-compressed before their mutual contact. Over a fleece of the carded Tencel fibers the hydro-formed bleached cellulose pulp fiber layer is applied, and the obtained bilayered structure is processed by water needling. The obtained nonwoven fabric is then dried, and subjected to further treatment by cutting and/or reeling. Depending on the required final form, the nonwoven fabric may be subjected to further treatment.

EXAMPLE 3

[0041] A water-needled biodegradable composite nonwoven fabric was obtained in an analogous manner to the one described in examples above. The first layer is formed in a process of carding 100% of non-bleached cotton fibers and has a basis weight of 20-25 g/m.sup.2. The second layer composed of 100% of cellulose pulp fibers obtained from scrap paper, is wet-formed in a wetlaid process on a casting-straining headbox type machine and has a basis weight of 25-35 g/m.sup.2. Both fiber layers are formed as non-bonded and non-compressed before their mutual contact. Over a fleece of the carded cotton fibers the hydro-formed cellulose pulp fiber layer obtained from scrap paper is applied, and the obtained bilayered structure is successively subjected to a water needling and chemical purification process by means of bleaching oxidizers. In this example, samples were prepared using a hydrogen peroxide solution, ozone, chlorine dioxide as oxidizers in combination, with assistance of adjuvants, which improve the process. After chemical purification the nonwoven fabric is washed and dried. Then the obtained nonwoven fabric is cut and reeled. Depending on the required final form, the nonwoven fabric may be subjected to further treatment.

EXAMPLE 4

[0042] A water-needled biodegradable composite nonwoven fabric was obtained in an analogous manner to the one described in examples above. The first layer is formed in a process of carding 100% of viscose (regenerated cellulose) fibers and has a basis weight of 17-20 g/m.sup.2. The second layer composed of 93% by weight of bleached softwood cellulose pulp fibers and 7% by weight of short staple thermoplastic bicomponent fibers containing PLA (polylactide), based on dry weight of the second layer, is wet-formed in a wetlaid process on a casting-straining headbox type machine and has a basis weight of 33-37 g/m.sup.2. Both fiber layers are formed as non-bonded and non-compressed before their mutual contact. Over a fleece of the carded viscose fibers a layer of hydro-formed combination of the cellulose pulp fibers and bicomponent thermoplastic fibers is applied, and the obtained bilayered structure is processed by water needling and dried at the sufficiently high temperature, to partly melt a meltable shell of bicomponent fibers, but not to damage a thermoplastic fiber core. Then the obtained nonwoven fabric is cut and reeled. Depending on the required final form, the nonwoven fabric may be subjected to further treatment.

EXAMPLE 5

[0043] A water-needled biodegradable composite nonwoven fabric was obtained in an analogous manner to the one described in examples above. The first layer is formed in a process of carding 100% of bleached cotton fibers and has a basis weight of 22-25 g/m.sup.2. The second layer composed of 100% of mechanically purified and chemically bleached cellulose pulp fibers, obtained from scrap paper, is wet-formed in a wetlaid process on a casting-straining headbox type machine and has a basis weight of 25-35 g/m.sup.2. Both fiber layers are formed as non-bonded and non-compressed before their mutual contact. Over a fleece of the carded bleached cotton fibers the layer of hydro-formed cellulose pulp fibers is applied, and the obtained bilayered structure is processed by water needling. The obtained nonwoven fabric is then dried, an subjected to further treatment by cutting and/or reeling. Depending on the required final form, the nonwoven fabric may be subjected to further treatment.

EXAMPLE 6

[0044] A water-needled biodegradable composite nonwoven fabric was obtained such as described in examples above. The first layer is formed in a process of carding 100% of cottonized hemp fibers and has a basis weight of of 25-35 g/m.sup.2. The second layer, composed of 90% by weight of bleached softwood cellulose pulp fibers and 10% of short staple thermoplastic bicomponent fibers, one of components of which is PLA (Polylactide), based on dry weight of the second layer, is wet-formed in a wetlaid process on a casting-straining headbox type machine and has a basis weight of 35-45 g/m.sup.2. Both fiber layers are formed as non-bonded and non-compressed before their mutual contact. Over a fleece of the carded cottonized hemp fibers a layer of hydro-formed combinations of the cellulose pulp fibers and bicomponent thermoplastic fibers is applied, and the obtained bilayered structure is processed by water needling and dried at the sufficiently high temperature, to partly melt a fusible shell of bicomponent fibers, but to not damage a thermoplastic fiber core. Then the obtained nonwoven fabric is cut and reeled. Depending on the required final form the nonwoven fabric may be subjected to further treatment.

EXAMPLE 7

[0045] A water-needled biodegradable composite nonwoven fabric was obtained such as described in examples above. The first layer is formed in a process of carding 100% viscose (regenerated cellulose) fibers and has a basis weight of 17-25 g/m.sup.2. The second layer composed of 90% by weight of bleached softwood cellulose pulp fibers and 10% by weight of short staple regenerated cellulose fibers—viscose fibers), based on dry weight of the second layer, is wet-formed in a wetlaid process on a casting-straining headbox type machine and has a basis weight of 33-37 g/m.sup.2. Both fiber layers are formed as non-bonded and non-compressed before their mutual contact. Over a fleece of the carded viscose fibers a layer of a combination of the hydro-formed fibers of cellulose and viscose pulps, and the obtained bilayered structure is processed by water needling. The obtained nonwoven fabric is then dried an subjected to further treatment by cutting and/or reeling. Depending on the required final form the nonwoven fabric may be subjected to further treatment.

EXAMPLE 8

[0046] Samples of the nonwoven fabrics obtained in Examples 1-7 were subjected to tests to verify their strength and pilling resistance.

[0047] All samples of the nonwoven fabric obtained in a process according to the invention exhibited suitable properties allowing their use in cosmetic applications and a household.