ABSORBENT PAD COMRPISING COATED SUPERABSORBENT PARTICLES

Abstract

An absorbent pad, such as a feminine hygiene article, according to the present disclosure comprises superabsorbent polymer particles (2). The superabsorbent polymer particles (2) are surface coated on an outer surface (3) with a coating agent (4), the coating agent (4) being water-soluble. The coated superabsorbent polymer particles (2) comprises an odour inhibiting substance (5) in powder form adhered to and/or mixed with the coating agent (3). The present disclosure also relates to methods of producing the absorbent pad (1).

Claims

1. An absorbent pad, such as a feminine hygiene article, the absorbent pad comprising: superabsorbent polymer particles, the superabsorbent polymer particles being surface coated on an outer surface with a coating agent, wherein the coating agent is water-soluble and is a polyol, for example glycerol, and wherein the coated superabsorbent polymer particles includes odour inhibiting substances in powder form adhered to and/or mixed with the coating agent.

2. The absorbent pad according to claim 1, wherein the odour inhibiting substances in powder form includes powder particles, the powder particles having an average particle size within the range of from 0.5 μm to 50 μm, the average size particle being measured according to ISO 13322-1:2014.

3. The absorbent pad according to claim 1, wherein the absorbent pad includes an amount of from 0.1 g to 20 g of the coated superabsorbent polymermparticles.

4. The absorbent pad according to claim 1, wherein the odour inhibiting substances in powder form is a silicate powder, such as an aluminosilicate mineral powder.

5. The absorbent pad according to claim 4, wherein the silicate powder is zeolite powder.

6. The absorbent pad according to claim 4, wherein the SiO:Al ratio of the silicate powder is from 10 to 1000.

7. The absorbent pad according to claim 1, wherein the coating agent is adhesively adhered to the outer surface of the superabsorbent polymer particle.

8. The absorbent pad according to claim 1, wherein the coating agent is water-soluble upon contact of the surface coated superabsorbent polymer particles with an aqueous liquid.

9. The absorbent pad according to claim 1, wherein the coating agent is in a liquid state at 23° C.

10. The absorbent pad according to claim 1, wherein the superabsorbent polymer is polyacrylic acid.

11. The absorbent pad according to claim 1, wherein the amount of coating agent based on the weight of the total weight of the superabsorbent polymer particles is from 0.5 wt. % to 5 wt. %.

12. The absorbent pad according to claim 1, wherein the amount of odour inhibiting substances based on the weight of the total weight of the superabsorbent polymer particles is from 5 wt. % to 35 wt. %.

13. The absorbent pad according to claim 1, wherein the absorbent pad comprises a topsheet, a backsheet and an absorbent core arranged between the topsheet and the backsheet and wherein the absorbent core includes the coated superabsorbent particles.

14. The absorbent pad according to claim 13, wherein the absorbent core includes a mixture of cellulose fibers and the coated superabsorbent particles.

15. A method of producing an absorbent pad, such as a feminine hygiene article, including superabsorbent polymer particles (2), the superabsorbent polymer particles being surface coated on an outer surface with a coating agent being water-soluble and is a polyol, for example glycerol, the methods comprising the steps of: a) providing superabsorbent polymer particles, b) mixing the superabsorbent polymer particles with the coating agent, c) applying an odour inhibiting substance in powder form to the surface coated superabsorbent polymer particles, and; d) forming an absorbent pad and integrating the coated superabsorbent polymer particles into the absorbent pad.

16. A method of producing an absorbent pad, such as a feminine hygiene article, including superabsorbent polymer particles, the superabsorbent polymer particles being surface coated on an outer surface with a coating agent being water-soluble and is a polyol, for example glycerol, the method comprising the steps of: a) providing 5 superabsorbent polymer particles, b) mixing the coating agent with an odour inhibiting substance in powder form, c) mixing the superabsorbent polymer particles with the mixture obtained in step b) and; d) forming an absorbent pad and integrating the coated superabsorbent polymer particles into the absorbent pad.

17. The method according to claim 15, wherein the odour inhibiting substance in powder form is a silicate powder, such as an aluminosilicate mineral powder, optionally the silicate powder having SiO:Al ratio of from 10 to 1000.

18. The method according to claim 17, wherein the silicate powder is a zeolite powder.

19. The method according to claim 15, wherein the coating agent is in a liquid state at 23° C.

20. The method according to claim 15, wherein the absorbent pad comprises a topsheet, a backsheet and an absorbent core arranged between the topsheet and the backsheet and wherein the method step d) include to incorporate the coated superabsorbent particles in the absorbent core.

21. The method according to claim 20, wherein the absorbent core includes a mixture of cellulose fibers and the coated superabsorbent particles.

22. The method according to claim 16, wherein the odor inhibiting substance in powder form is a silicate powder, such as an aluminosilicate mineral powder, optionally the silicate powder having SiO:Al ratio of from 10 to 1000.

23. The method according to claim 22, wherein the silicate powder is a zeolite powder.

24. The method according to claim 16, wherein the coating agent is in a liquid state at 23° C.

25. The method according to claim 16, wherein the absorbent pad comprises a topsheet, a backsheet and an absorbent core arranged between the topsheet and the backsheet and wherein the method step d) include to incorporate the coated superabsorbent particles in the absorbent core.

26. The method according to claim 25, wherein the absorbent core includes a mixture of cellulose fibers and the coated superabsorbent particles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention will be further explained hereinafter by means of non-limiting examples and with reference to the appended drawings wherein:

[0045] FIG. 1 illustrates a superabsorbent particle according to the present disclosure;

[0046] FIG. 2 illustrates a fibrous network including the superabsorbent polymer particles;

[0047] FIG. 3 shows a top plan view of an absorbent pad;

[0048] FIG. 4 shows a bar diagram illustrating the results of an odour inhibition test between absorbent pads according to the present disclosure and reference samples; and

[0049] FIG. 5 shows a bar diagram illustrating the results from an odour inhibition test of absorbent core samples comprising coated superabsorbent polymer particles according the present disclosure and compared with reference absorbent core samples comprising 20 mg of zeolite powder.

DETAILED DESCRIPTION

[0050] The invention will be described more closely below by reference to an exemplary embodiment. The invention may however be embodied in many different forms and should not be construed as limited to the embodiments set forth in the drawings and the description thereto.

[0051] FIG. 1 schematically shows a coated superabsorbent polymer particle 2 according to the present disclosure. The superabsorbent polymer particle 2 is coated with a coating agent 4 being water-soluble and in a liquid form at 23° C., such as glycerol, on an outer surface 3 thereof. The coating agent 4 is provided as a surface-coating and is adhesively adhered to the outer surface 3 of the superabsorbent polymer particle 2. The coating agent 4 is mixed with the odour inhibiting substance 5 in powder form, such as a zeolite powder, to provide the coating agent 4 with a suitable viscosity and stickiness for adhering well to the superabsorbent particles 2. A mixture of the coating agent 4 and the odour inhibiting substance in powder form 5 may for example comprise coating agent 4 in an amount of 5 to 25% and the odour inhibiting substance in powder form 5 in an amount of 75% to 95%. As an outermost layer, a powder layer of the odour inhibiting substances in powder form 5 has been applied on the sticky coating layer including the mixture of the coating agent 4 and the odour inhibiting substance in powder form 5. The superabsorbent particles may be polyacryl-based superabsorbent particles.

[0052] FIG. 2 illustrates a portion of an absorbent core 8, the absorbent core 8 including a fibrous structure 9 comprising a network of cellulosic fibers 10 mixed with coated superabsorbent polymer particles 2. The absorbent core 8 may include from 0.1 grams to 20 grams of the coated superabsorbent polymer particles 2. As the coating agent is water-soluble, the coating may upon contact with bodily fluid dissolve from the superabsorbent particles and the slippery surface of the superabsorbent particles upon wetting and the absorbent properties of the superabsorbent particles may remain unaffected. The odour inhibiting effect of the odour inhibiting substance in powder form will also be preserved, as the odour inhibiting substance together with the coating agent will remain in the fiber network.

[0053] FIG. 3 schematically shows an absorbent pad 1 according to the present disclosure, the absorbent pad 1 being in the form of a sanitary napkin 1. The sanitary napkin 1 comprises a fluid permeable topsheet 6, a backsheet 7 and an absorbent core 8 interposed between the topsheet 6 and the backsheet 7. The absorbent pad 1 is provided with laterally extending flaps 11 being provided with attachment means 12 on a garment facing side. The backsheet 7 may be provided with an adhesive provided on an outwardly oriented side for attachment of the sanitary article 1 to an undergarment on a user-facing side of the undergarment.

[0054] The topsheet may be a plastic perforated film and/or may include or consist of fibrous nonwoven layer(s). The fibrous nonwoven layers may be spunbonded, meltblown, carded, hydroentangled, wetlaid etc. Suitable nonwoven materials can be composed of natural fibers, such as woodpulp or cotton fibres, synthetic thermoplastic fibres, such as polyolefins, polyesters, polyamides and blends and combinations thereof or from a mixture of natural and synthetic fibres. The materials suited as topsheet materials should be soft and non-irritating to the skin and be readily penetrated by body fluid, such as urine or menstrual fluid. The topsheet material may essentially consist of synthetic thermoplastic fibers, such as polyolefins, polyesters, polyamides and blends and combinations thereof. The synthetic fibers may be monocomponent fibers, bicomponent fibers or multicomponent fibers including polyesters, polyamides and/or polyolefins such as polypropylene and polyethylene.

[0055] The absorbent core may be of any conventional kind. In addition to superabsorbent polymer particles, examples of commonly occurring absorbent materials are cellulosic fluff pulp, tissue layers, absorbent foam materials, absorbent nonwoven materials or the like. It is common to combine cellulosic fluff pulp with superabsorbent polymer particles in an absorbent structure. It is also common to have absorbent structures comprising layers of different material with different properties with respect to liquid acquisition capacity, liquid distribution capacity and storage capacity. This is well-known to the person skilled in the art and does therefore not have to be described in detail. The thin absorbent bodies, which are common in today's sanitary articles, often comprise a compressed mixed or layered structure of cellulosic fluff pulp and superabsorbent. The size and absorbent capacity of the absorbent structure may be varied to be suited for different uses such as sanitary articles, pantyliners, adult incontinence pads and diapers, baby diapers, pant diapers, etc.

[0056] The backsheet may consist of a thin plastic film, e.g. a polyethylene or polypropylene film, a nonwoven material coated with a liquid impervious material, a hydrophobic nonwoven material, which resists liquid penetration. Laminates of plastic films and nonwoven materials may also be used. The backsheet material can be breathable so as to allow vapor to escape from the absorbent structure, while still preventing liquids from passing through the backsheet material.

Experimental Section

Absorbent Capacity Test

[0057] In order to evaluate the impact of the coating on the absorbency properties of the superabsorbent polymer particles according to the present disclosure, the free swelling and retention capacity of three different samples of coated superabsorbent particles were prepared, evaluated and compared with a reference sample of a superabsorbent polymer particle coated only with a zeolite powder using the methods Free Swelling Capacity (FSC) as described in the standard method NWSP 240.0 (R2) and Centrifuge Retention Capacity (CRC) as described in the standard method NWSP 241.0 (R2).

[0058] The coating agents tested were glycerol and two different polyethylene glycols (PEG); PEG1000 and PEG300. PEG 300 is a polyethylene glycol having an average molecular weight of 300 g/mol and PEG 1000 is a polyethylene glycol having an average molecular weight of 1000 g/mol.

[0059] The coating agent were added to the superabsorbent particles (Favor SXM 9420 from Evonik) in a liquid form, which means that the PEG 1000 was heated to 50° C. before it was added to the superabsorbent particles. In a subsequent step the superabsorbent polymer particles coated with the coating agent were mixed with zeolite powder (ZEOflair 100 from Zeochem AG) and a small amount of active carbon. A mix of zeolite powder and active carbon powder was thus added to the different samples of the coated superabsorbent polymer particles, the zeolite powder in an amount of 10 wt. %, of the amount of superabsorbent polymer particles, and 0.1 g active carbon. The active carbon was included in order to enable visual verification that the powder mix of zeolite and active carbon was evenly distributed onto the superabsorbent particles. The glycerol and the PEG 300 was added in an amount of 1.75 wt. %, of the amount of superabsorbent polymer, and PEG 1000 was added in an amount of 2.75 wt. %, of the amount of superabsorbent polymer.

[0060] The Free Swelling Capacity of the coated superabsorbent polymer particles were measured after 1 minute, after 3 minutes and after 30 minutes and the Centrifuge Retention Capacity of the coated superabsorbent polymer particles was also measured. Reference values obtained from the superabsorbent polymer particle manufacturer are included in the tables.

[0061] The superabsorbent particles in table 1 are reference samples and are covered with 10 wt. % zeolite powder, based on the weight of the superabsorbent particles, and 0.1 g active carbon. Values adjusted for the additional 10 wt. % of zeolite powder included are also shown below.

TABLE-US-00001 TABLE 1 FSC FSC FSC CRC CRC 1 min 5 min 30 min g/g % Ref SXM9420 + Average g/g 19 41 51 30 59 10% Zeolite and Std 1.1 1.0 0.7 0.2 0.7 0.1 g AC Adjusted for 20.7 46.0 56.3 33 10% zeolite 20180702-006 Ref. 20 48 58 34 58

[0062] As seen in table 1, the free swelling capacity and the centrifuge retention capacity of the superabsorbent polymer particles were in principle unaffected by the addition of zeolite powder.

[0063] In table 2 results from tests on superabsorbent polymer particles coated with 1.75 wt. % PEG300, 10 wt. % zeolite powder and 0.1 g active carbon are illustrated. Values adjusted for the additional 10 wt. % of zeolite powder included are also shown below.

TABLE-US-00002 TABLE 2 FSC FSC FSC CRC CRC 1 min 5 min 30 min g/g % Ref SXM9420 Average 19 40 50 30 59 1.75% PEG300 g/g 10% zeolite and Std 0.5 0.8 0.5 0.1 0.6 0.1 g AC Adjusted for 20.6 44.9 55.5 33 60 10% zeolite 20180702-006 Ref. 20 48 58 34 58

[0064] As illustrated in table 2, there is no significant impact of the coating of the superabsorbent polymer particles on the free swelling capacity and the centrifuge retention capacity of the superabsorbent polymer particles coated with PEG 300 and zeolite powder.

[0065] In table 3 results from tests on superabsorbent polymer particles coated with 1.75 wt. % Glycerol, 10 wt. % zeolite and 0.1 g active carbon are shown.

TABLE-US-00003 TABLE 3 FSC FSC FSC CRC CRC 1 min 5 min 30 min g/g % SXM9420 Average 16 40 49 30 60 1.75% Glycerol g/g 10% Zeolit and Std 0.3 0.7 1.4 0.2 1.7 0.1 g AC Adjusted for 18.0 44.0 54.8 33 60 10% zeolite 20180702-006 Ref. 20 48 58 34 58

[0066] As illustrated in table 3, there is no significant impact of the coating of the superabsorbent polymer particles on the free swelling capacity and the centrifuge retention capacity on the superabsorbent polymer particles coated with glycerol and zeolite powder.

[0067] In table 4 the results from tests made on superabsorbent polymer particles coated with 2.75% PEG, 10% zeolite and 0.1 g AC are shown.

TABLE-US-00004 TABLE 4 FSC FSC FSC CRC CRC 1 min 5 min 30 min g/g % Ref SXM9420 + 10% Average 19 42 50 29 58 Zeolite + 2.75% g/g PEG1000, Std 1.1 0.9 0.4 0.5 0.5 and 0.1 g AC Adjusted for 20.7 46.5 55.3 33 60 10% zeolite Ref. 20.0 47.0 57.0 34 58

[0068] As illustrated in table 4, there is no significant impact of the coating of the superabsorbent polymer particles on the free swelling capacity and the centrifuge retention capacity on the superabsorbent polymer particles coated with PEG 1000 and zeolite powder.

Odour Inhibition Tests

[0069] Measurements were performed to evaluate the odour inhibition efficiency in an absorbent pad according to two different methods illustrated in FIGS. 4 and 5. A first method IMOR Feminine Between was carried out at RISE—Research Institute of Sweden, in Gothenburg, Sweden and a second method RO-liners was carried out at Essity Hygiene and Health AB, in Gothenburg, Sweden.

[0070] In the respective methods, the test liquid are used to simulate the odour of used feminine liners. The test liquid consists of a buffer solution, pH 4.0, comprising the odorants diacetyl, 3-methylbutanal, dimethyl disulphide (DMDS), 1-octene-3-one and isovaleric acid (IVA).

IMOR Feminine Between

[0071] In a first test, IMOR Feminine Between, illustrated in FIG. 4, a reference liner; Liner Long Protege Slip, Deliplus was compared to a test liner; Liner Long Protege Slip, Deliplus including 20 mg zeolite powder (ZepFlair), 0.2 mg active carbon.

[0072] Test Set-Up [0073] 2.5 ml of test liquid was added to each sample [0074] The liners were tested in triplicates

Test Method

[0075] As described above, test liquids are used to simulate the odour of used feminine liners. The test liquid consists of a buffer solution, pH 4.0, comprising the odorants diacetyl, 3-methylbutanal, dimethyl disulphide (DMDS), 1-octene-3-one and isovaleric acid (IVA).

[0076] To each of the liners 2.5 ml of the test liquid were added, and the wetted samples were equilibrated at 35° C. for 4 hours in a 4.8 l glass vessel (IMOR vessel).

[0077] After 4 hours, the odorants remaining in gas phase in the glass vessels are sampled on an adsorbent Tenax tube and samples are taken out from the glass vessels and analysed using Gas Chromatography. The concentration of each odorant is reported as ng/I. The results are compared to those of a reference and are illustrated in FIG. 4.

RO-Liner

[0078] In a further method, odour inhibition of absorbent core samples comprising coated superabsorbent polymer particles according to this disclosure was evaluated and compared with a reference absorbent core samples comprising 20 mg of zeolite powder. The purpose of the test was to investigate any possible negative impact on the odour reducing effect of the zeolite powder when being coated on superabsorbent polymer particles with a coating agent in accordance with the present disclosure. The result being illustrated in FIG. 5.

[0079] The coating agents tested were glycerol and two different polyethylene glycols (PEG); PEG1000 and PEG300, wherein PEG 300 is a polyethylene glycol having an average molecular weight of 300 g/mol and PEG 1000 is a polyethylene glycol having an average molecular weight of 1000 g/mol.

[0080] The coating agent was added to the superabsorbent particles in a liquid form, which means that the polyethylene glycol 1000 (PEG) was heated to 50° C. before it was added to the superabsorbent particles. In a subsequent step the superabsorbent particle coated with the coating agent were mixed with zeolite powder (ZEOflair 100 from XXXX) mixed with a small amount of active carbon. A mix of zeolite powder and active carbon powder was thus added to the different samples of the coated superabsorbent polymer particles, the zeolite powder in an amount of 10 wt. of the amount of superabsorbent polymer particles, and 0.1 g active carbon. The active carbon was included in order to enable visual verification that the powder mix of zeolite and active carbon was evenly distributed onto the superabsorbent particles. The respective coating agent of the glycerol and the PEG 300 was added in an amount of 1.75 wt. % of the amount of superabsorbent polymer and PEG 1000 was added in an amount of 2.75 wt. % of the amount of superabsorbent polymer.

[0081] All samples, including the reference sample, contains 20 mg zeolite powder. The coated superabsorbent particles was included into a cut sample absorbent core having a diameter of 50 mm, the absorbent core comprising cellulose fibers and the coated superabsorbent polymers. The absorbent core was covered with a nonwoven topsheet and sealed with a pre-glued nonwoven covering the back and the sides of the respective sample. The nonwoven material being an 18 gsm hydrophilic spunbond, 100% polypropylene, nonwoven material.

[0082] Test Set-Up [0083] 2.5 ml of test liquid was added to each sample [0084] The samples were tested in triplicates, one day for each method.

[0085] As described above, test liquids are used to simulate the odour of used feminine liners. The test liquid consists of a buffer solution, pH 4.0, comprising the odorants diacetyl, 3-methylbutanal, dimethyl disulphide (DMDS), 1-octene-3-one and isovaleric acid (IVA).

[0086] To each of the samples 2.5 ml of the test liquid were added, and the wetted samples were equilibrated at 35° C. for 4 hours in a 500 ml glass bottle (Duran bottle).

[0087] During this time, the odour inhibitor reacts with the odorants. After 4 hours, the odorants remaining in gas phase in the glass bottle are sampled on an adsorbent Tenax tube and samples are taken out from the glass bottles and analysed using Gas Chromatography. The concentration of each odorant is reported as ng/I. The results are compared to those of a reference.

[0088] In the respective methods, the sample with the least good result was set as the normalized result, i.e. 1.0, and the results of the other samples were compared with this normalized result 1.0.

Results

[0089] In the results from the Feminine in Between method, shown in FIG. 4, it is clearly illustrated that the zeolite powder added to the absorbent core has a significant odour inhibiting effect on the odorants included in the test liquids.

[0090] In the RO-Liner method illustrated in FIG. 5, it may be seen that when comparing the coating agents and their possible impact on the odour inhibiting effect of the zeolite powder, glycerol has the overall best performance on each of the three evaluated odours. Glycerol did not at all affect the odour inhibiting effect of the zeolite powder. The coated superabsorbent polymer particles using PEG 300 as coating agent also showed a very low negative impact of the coating agent on the odour inhibiting effect on at least two of the odours, Diacetyl and DMDS.

[0091] The coated superabsorbent polymer particles using PEG 1000 as coating agent showed an odour inhibiting effect on each of the odours, but the coating agent PEG 1000 reduced the effect to some degree when comparing with an absorbent core including the same amount of zeolite powder in free form.