Odour control material, method for preparation of an odour control material and an absorbent product comprising the odour control material

Abstract

The present invention relates to an odor control material consisting of a water-insoluble particulate odor control agent and a thermoplastic water-soluble carrier matrix encapsulating the odor control agent. The carrier matrix dissolves when in contact with an aqueous solution, such as urine and the odor control material is obtained by means of thermoforming. The invention relates also to a method for the preparation of the odor control material and the use of the odor control material in absorbent products. The present odor control material minimizes dusting problems caused by particulate odor control agents in production processes.

Claims

1. An odour control material consisting of a water-insoluble particulate odour control agent and a thermoplastic water-soluble carrier matrix encapsulating the odour control agent, wherein the carrier matrix dissolves when in contact with an aqueous solution, and wherein the odour control material is in the form of a film, fibres or filaments, or a fibre web, obtained by means of extrusion.

2. The odour control material according to claim 1, wherein the particulate odour control agent is activated carbon, zeolite or a starch based particulate odour control agent.

3. Odour control material according to claim 2, wherein the particulate odour control agent is activated carbon.

4. Odour control material according to claim 1, wherein the thermoplastic water-soluble carrier matrix comprises a water-soluble polymer selected from the group consisting of: polyethylene oxide, polyvinyl alcohol, polysaccharide, polyacrylamide, polyvinylamine, polyvinylpyridine, polyvinylpyrrolidine, and a mixture thereof.

5. Odour control material according to claim 1, wherein the water-soluble carrier matrix comprises an additive selected from the group consisting of: plastisizer, stabilizer, agent improving dispersibility, pH regulating agent, and antimicrobial substances.

6. Odour control material according to claim 1, wherein the weight ratio carrier matrix to odour control agent is from 1:10 to 10:1.

7. Odour control material according to claim 1, wherein the odour control material is in the form of a film and has a thickness of 10 to 2000 micrometers.

8. Odour control material according to claim 1, wherein the odour control material is in the form of fibres which are staple fibres and have a fibre length of from 1 to 40 mm and linear mass density of from 1.7 to about 10,000 dtex.

9. Odour control material according to claim 1, wherein the odour control material is a nonwoven fibre web.

10. Method for preparation of the odour control material according to claim 1, the method comprising the steps of: i. providing a water-soluble thermoplastic carrier matrix material in a solid form; ii. providing a particulate odour control agent in a solid form; iii. blending the particulate odour control agent with the carrier matrix material to provide an even dispersion in which the particulate odour control agent is solid; iv. heating the carrier matrix material to a melting temperature of from about 70 to about 300° C. to at least partially melt the carrier matrix material, wherein the particulate odour control agent remains solid; v. extruding the even dispersion to form a film, fibres or a fibre web; vi. cooling the extruded material; vii. collecting the formed material.

11. Method according to claim 10, wherein the odour control material obtained is a film.

12. Method according to claim 11, wherein the method further comprises a step of a step punching the film to provide holes in the film and/or a step of crushing the obtained film to provide flakes.

13. Method according to claim 10, wherein the odour control material obtained is in the form of staple fibres, wherein the extrusion is performed through a spinneret to provide fibres having a linear mass density of from 1.7 dtex to 10,000 dtex.

14. Method according to claim 13, wherein the method further comprises a step of providing a fibre web being a meltblown material, spunbond material or a carded fibrous web.

15. Absorbent product comprising a back sheet, being distal from the body of the wearer in use of the product, a top sheet being proximal to the body of the wearer in use of the product, and an absorbent structure located between the top sheet and the backsheet, wherein the product comprises the odour control material according to claim 1.

16. Absorbent product according to claim 15, wherein the absorbent product comprises a further layer, the layer being the odour control material.

17. Absorbent product according to claim 15, wherein the odour control material is comprised as fibres or flakes in the absorbent product.

18. Absorbent product according to claim 17, wherein the fibres or flakes are comprised in an absorbent core of the absorbent product.

19. Odour control material according to claim 1, wherein the aqueous solution is urine.

Description

SHORT DESCRIPTION OF FIGURES

(1) Examples of different embodiments according to the present invention are further illustrated in the accompanying Figures in which:

(2) FIG. 1 shows schematically layers of an absorbent product comprising the odour control material of the present invention in form of a film.

(3) FIG. 2 shows schematically layers of an absorbent product comprising the odour control material of the present invention in form of a punched film.

(4) FIG. 3 shows schematically layers of an absorbent product comprising the odour control material of the present invention in form of film flakes.

(5) FIG. 4 shows schematically layers of an absorbent product comprising the odour control material of the present invention in form of fibres in a core.

(6) FIG. 5 shows schematically layers of an absorbent product comprising the odour control material of the present invention in form of fibres in an acquisition material.

(7) FIG. 6 shows schematically layers of an absorbent product comprising the odour control material of the present invention in form of a nonwoven web.

(8) FIG. 7 and FIG. 8 show schematically layers of an absorbent product comprising the odour control material of the present invention in form of a punched nonwoven.

(9) FIG. 9 shows schematically a test device used in Example 7.

(10) FIG. 1 shows an example of layers of an absorbent product, in which one of the layers is the odour control material of the present invention. The product comprises a surface or top layer 1 of nonwoven material and a liquid impervious backing material layer 2. In between the top layer 1 and the backing layer 2, below the top layer 1, an acquisition material layer 3a is provided to enhance the liquid distribution in the product. An odour control material in the form of a film 4 according to the present invention is provided below the acquisition layer 3a and on top of an absorbent core 5. The film 4 has a smooth surface and is not punched. The film 4 may come into contact with liquid, such as urine, and thus, the carrier matrix is dissolved and the particulate odour control agent is released. Thereby, an effective odour control may be achieved and odours can be prevented from arising.

(11) FIG. 2 shows another embodiment of the present invention similar to the one of FIG. 1 but in which the film material layer 4a is punched. Also flakes 4c of the film may be present in this layer. The other layers of the product are a top layer 1 of nonwoven material, absorbent core 5 and a backing material layer 2. Below the top layer 1, an acquisition material layer 3b is provided.

(12) FIG. 3 shows a further embodiment of the present invention in which a top layer 1 of nonwoven material and a backing material layer 2 are provided. Below the top layer 1, an acquisition material layer 3c is provided. Flakes 4c of a film material according to the present invention are added to an absorbent core 5 of the absorbent product. In this embodiment, also brittle water-soluble carrier matrix materials may be used.

(13) FIG. 4 shows a further embodiment, in which the odour control material of the present invention is provided in the form of fibres 6a. Also in this embodiment, a top layer 1 of a nonwoven material and a backing material layer 2 are provided. Below the top layer 1, an acquisition material layer 3d is provided. Odour control material fibres 6a are blended with fibres of an absorbent core 5. In this way the odour control material may be added to the absorbent product in one step, whereby the odour control material of the present invention may be used in an existing process in an easy way.

(14) Still another embodiment is shown in FIG. 5. Also, in this embodiment a top layer 1 of nonwoven material and a backing material layer 2 are provided. Below the top layer 1, an acquisition material layer 3e is provided, in which odour control material in the form of fibres 6b is mixed. Below the acquisition material, 3e, an absorbent core 5 is provided.

(15) In FIG. 6 an embodiment is shown in which, as above, a top layer 1 of nonwoven material and a backing material layer 2 are provided. Below the top layer 1, odour control material in the form of a nonwoven 7a according to the present invention is provided. Below the nonwoven 7a an absorbent core 5 is provided. The odour control material is provided in the form of a nonwoven, which may be rolled up to a roll, is easy to use in existing processes and is easily adapted to online manufacturing processes.

(16) In FIGS. 7 and 8, odour control material in the form of a punched nonwoven web 7b according to the present invention is provided. As above in connection with the embodiments shown in FIGS. 1-6, a top layer 1 of nonwoven material and a backing material layer 2 are provided. In FIG. 7, punched nonwoven is provided under the top layer 1. Below the punched nonwoven, an absorbent core 5 is provided. In FIG. 8, a further layer of nonwoven 7b is provided below an absorbent core and above the backing material layer 2. By providing punches in the nonwoven web, the water-solubility of the carrier material is further enhanced.

EXAMPLES

(17) In the Examples below odour control material according to the present invention have been prepared. Molecular weight expressed in Daltons (Da) corresponds approximately to a molecular weight expressed in grams per mole.

Example 1

(18) Preparation of an Odour Control Material According to the Present Invention in the Form of Odour-Reducing Flakes Containing 50 Weight-% Activated Carbon in Polyethylene Oxide with a Molecular Weight of 100,000 Da (Material A).

(19) 5 g of activated carbon powder, Norit SA2, delivered by Sigma-Aldrich, was mixed in a beaker with 5 g polyethylene oxide powder with a molecular weight of 100,000 Da, also purchased from Sigma Aldrich. The beaker was placed in an oven at 130° C. for about 1 hour in order to melt the polyethylene oxide. During this period the blending was manually mixed using a stainless steel spoon. The blending was then placed between two Teflon cloths and a pre-heated steel plate and a pre-heated steel cylinder, both with a temperature of about 130° C. were used to manually compress the material to a film. This was achieved by placing the Teflon cloths on the heated plate and rolling the cylinder several times over the clothes until the material between the cloths had been squeezed out to a film. The material was then cooled to room temperature and the Teflon cloths were then detached from the polyethylene oxide film with activated carbon particles. The film, which had an approximate thickness of 1 mm was then manually torn into flakes with the approximate area of 3 mm*3 mm.

Example 2

(20) Preparation of an Odour Control Material According to the Present Invention in the Form of Odour-Reducing Flakes Containing 50 Weight-% Activated Carbon in Polyethylene Oxide with a Molecular Weight of 600,000 Da (Material B)

(21) 5 g of activated carbon powder, Norit SA2, delivered by Sigma-Aldrich, was mixed in a beaker with 5 g polyethylene oxide powder with a molecular weight of 600,000 Da, also purchased from Sigma Aldrich. The beaker was placed in an oven at 130° C. for about 1 hour in order to melt the polyethylene oxide. During this period the blending was manually mixed using a stainless steel spoon. The blending was then placed between two Teflon cloths and a pre-heated steel plate and a pre-heated steel cylinder, both with a temperature of about 130° C. were used to manually compress the material to a film. This was achieved by placing the Teflon cloths on the heated plate and rolling the cylinder several times over the clothes until the material between the cloths had been squeezed out to a film. The material was then cooled to room temperature and the Teflon cloths were then detached from the polyethylene oxide film with activated carbon particles. The film, which had an approximate thickness of 1 mm was then manually torn into flakes with the approximate area of 3 mm*3 mm.

Example 3

(22) Preparation of an Odour Control Material According to the Present Invention in the Form of Odour-Reducing Flakes Containing 50 Weight-% Activated Carbon in a Mixture of Saccharose and Glucose (Material C).

(23) 3.86 g granulated sugar from the company Dansukker was placed in a beaker and added 1.14 g distilled water. The mixture was slowly heated on a heating plate until all sugar had melted. Then, 1.14 g glucose with the trade name Dextropur, bought from a local food shop, was added and the temperature of the heating plate was increased. When the temperature of the sugar had reached about 152° C., 5 g activated carbon powder, Norit SA2, delivered by Sigma-Aldrich, was manually mixed into the melted sugar by the aid of a spoon of stainless steel. The mixture was then placed between two Teflon cloths and kept in an oven at about 150° C. for about 5 minutes. The Teflon cloths, with the mixture of melted sugar and activated carbon were then placed on a preheated steel plate, with a temperature of 150° C. A pre-heated steel cylinder, with a temperature of about 150° C., was used to manually compress the material to a film. This was achieved by rolling the cylinder several times over the clothes until the material between the cloths had been squeezed out to a film. The material was then cooled to room temperature and the Teflon cloths were then detached from the sugar film with activated carbon particles. The film, which had an approximate thickness of 1 mm was then manually torn into flakes with the approximate area of 3 mm*3 mm.

Example 4

(24) Preparation of an Odour Control Material According to the Present Invention in the Form of Odour-Reducing Flakes Containing 50 Weight-% Activated Carbon in Thermoplastic Starch (Material D)

(25) 2.14 g starch, Solcoat 55 from Solam AD, 2.14 g Urea, Sigma Aldrich, and 0.72 g Sorbitol, Sigma Aldrich, was added 10 a beaker. To this mixture 5 g distilled water and 5 g of activated carbon powder, Norit SA2, delivered by Sigma-Aldrich, were added. After thorough mixing, the beaker was placed in an oven with the temperature 150° C. At this temperature, the water first evaporates and then urea reacts with starch forming starch carbamate. This modified starch plasticized with sorbitol has thermoplastic properties. The blending was then placed between two Teflon cloths and a pre-heated steel plate and a pre-healed steel cylinder, both with a temperature of about 130° C. were used to manually compress the material to a film. This was achieved by placing the Teflon cloths on the heated plate and rolling the cylinder several times over the clothes until the material between the cloths had been squeezed out to a film. The material was then cooled to room temperature and the Teflon cloths were then detached from the thermoplastic starch film with activated carbon particles. The film, which had an approximate thickness of 1 mm was then manually torn into flakes with the approximate area of 3 mm*3 mm.

Comparative Example 5

(26) Comparative Example of a Material not Included in the Invention. Preparation of Flakes Containing 50% Activated Carbon in Styrene-Acrylate Copolymer (Material E)

(27) 5 g of activated carbon powder, Norit SA2, delivered by Sigma-Aldrich, was mixed in a beaker with 10 g of a styrene-acrylate latex dispersion with the trade name Mowilith TA2250S from the company Celanese. The latex dispersion had a content of styrene-acrylate copolymer of 50% in water. After thorough mixing, the beaker was placed in an oven with a temperature of 150° C. for about 3 h in order to evaporate the water. The mixture of activated carbon in styrene-acrylate copolymer was then placed between two Teflon cloths and compressed to a film by the aid of a press with heated plates. A plate temperature of 150° C. was used and a mechanical load of 400 kN was applied on the material for about 1 minute. The material was then cooled to room temperature and the Teflon cloths were then detached from the styrene-acrylate copolymer film with activated carbon particles. The film, which had an approximate thickness of 1 mm was then manually torn into flakes with the approximate area of 3 mm*3 mm.

Example 6

(28) Dissolution of the Polymer Carrier Matrix

(29) This test was performed to investigate how much of the carrier matrix that was dissolved in one minute in a tempered saline solution.

(30) Materials:

(31) Saline solution, temperature 35-37° C.

(32) Vortex apparatus IK MS2, speed 1500 rpm

(33) Test tube 15 ml

(34) Filter paper, 2 layers, Tork 23 g/m2

(35) Funnel

(36) Polymer carrier matrix, thickness 300-2000 μm, with 50 weight-% of activated carbon

(37) Prov A Polyethylene oxide polymer 100,000 Da Prov B Polyethylene oxide polymer 600,000 Da Prov C Mixture of saccharose and glucose Prov D Thermoplastic starch Prov E Styrene-acrylate copolymer

(38) 0.02 g of the polymer carrier matrix with activated carbon was added to the test tube. Each material was in 1 to 3 pieces. Three ml of the tempered saline solution was poured into the test tube which was instantly placed on the Vortex. After 1 minute the content of the test tube was filtered. After filtration the filter paper was folded up and a visual assessment was made with respect to the proportion of the material which had been dissolved and/or softened and distributed on the filter paper.

(39) TABLE-US-00001 TABLE 1 Polymer carrier matrix Dissolution % Prov A >90 Prov B >90 Prov C 100 Prov D 100 Prov E 0

Example 7

(40) Preparation of an Odour-Reducing Thread Containing 50 Weight-% Activated Carbon in Polyethylene Oxide with a Molecular Weight of 600,000 Da

(41) 10 g of activated carbon powder, Norit SA2, delivered by Sigma-Aldrich, was mixed in a beaker with 10 g polyethyleneoxide powder with a molecular weight of 600,000 Da, also purchased from Sigma Aldrich. The beaker was placed in an oven at 130° C. for about 1 hour in order to melt the polyethylene oxide. During this period the blending was manually mixed using a stainless steel spoon. The blending was then transferred to a laboratory device, see FIG. 9, for extrusion of threads. This device consisted of a tube 10 in stainless steel with an inner diameter d of 18 mm and a length of about 150 mm. A nozzle with one hole 11 with the diameter 0.8 mm had been attached to one of the tube ends. A piston 12 with good fit was inserted into the tube. The extrusion device was then kept in an oven with the temperature 150° C. for about 1 hour. After heating, threads were prepared by pressing the piston into the tube by the aid of a workshop press. A thread of hot polyethylene oxide with particles of activated carbon was hereby extruded through the nozzle. The thread quickly became solid by the temperature reduction achieved by the cooling effect of the surrounding air. The length and weight of the thread were measured and its average fibre weight (linear mass density) was determined to about 9000 dtex.

Example 8

(42) Measurement of Odour Reduction

(43) Flakes prepared according to examples 1-4 were added to fluffed pulp and the ability or this mixture to reduce odours was determined by the following method.

(44) The sample was placed in a 60 ml vial, after which 3.9 ml of 0.01 M phosphate buffered saline solution pH 7.4 from Sigma was added. Then 0.1 ml PEG300 with DMS (dimethyl sulfide), DMDS (dimethyl disulfide) and IVA (isovaleric aldehyde) were added so that the total amount of all three odour substances was 1000 ng/ml of each substance.

(45) After 3 hours at 35° C. a SPME fiber (Supelco), 75 μm Carboxen-PDMS, was injected into the headspace above the sample and after an additional 0.5 hour the SPME fiber was analyzed with gas chromatography (GC), Thermo Finnigan Trace, with a MS detector. The peak area of each odour substance was determined for samples with treated pulp and the untreated reference pulp. The GC settings were:

(46) Temperature program for GC: 30° C. (7 min); 3° C./min −70° C. (0 min), 40° C./min −250° C. (7 min).

(47) Column: ZB-624 (Zebron), 30 m, 0.25 mm i.d. 1.40 μm film thickness

(48) Inlet temperature: 250° C.

(49) Transfer line: 220° C.

(50) Mode; Splitless

(51) MS: SIM (single ion monitoring). When DMS, IVA and DMDS were analyzed the following mass numbers were detected: 45, 46, 47, 57, 58, 61, 62, 79, 86 and 94.

(52) The odour reduction is calculated for each odour substance from equation [1]
Odour reduction=(1−A.sub.1/A.sub.0)×100%
Where, A.sub.1=Peak area of actual sample A.sub.0=peak area for sample with pure fluffed pulp

(53) To measure odour reduction according to the above-described method, a fluffed pulp was prepared by dry defibrillation of roll fluff pulp named IP RW Supersoft fluff pulp, produced by the company International Paper. Samples containing 1 g of this fluffed pulp were then prepared and their odour-reducing ability was determined. As a comparative sample, 1 g fluffed pulp was mixed with 0.3 g activated carbon powder, Noril SA2, delivered by Sigma-Aldrich. Samples 3-6 were prepared by mixing 1 g fluffed pulp with flakes according to the invention. As these flakes had an activated carbon content of 50 weight-%, 0.6 g was added to each sample. This means that samples 2-6 all contained 0.3 g activated carbon. All prepared samples are described in table 2.

(54) TABLE-US-00002 TABLE 2 Sample no Content 1 1 g fluffed pulp 2 1 g fluffed pulp + 0.3 g activated carbon 3 1 g fluffed pulp + 0.6 g flakes from example 1 4 1 g fluffed pulp + 0.6 g flakes from example 2 5 1 g fluffed pulp + 0.6 g flakes from example 3 6 1 g fluffed pulp + 0.6 g flakes from example 4

(55) The odour-reducing ability of the samples described in table 2 was determined by analyzing the concentration of three relevant odorants, dimethylsulfide, dimethyldisulfide and isovaleric aldehyde, in the gas phase above the samples after injection of a test solution containing these compounds into vials with the different samples. The odour reduction is calculated by comparing the peak area of the actual sample with peak area of sample 1 according to equation [1]. The results from this investigation are shown in tables 3-5.

(56) TABLE-US-00003 TABLE 3 Relative peak area from GC analysis and calculated reduction of dimethylsulfide Sample no. Relative peak area Calculated odour reduction 1 1 0 2 0.059 94.1 3 0.087 91.3 4 0.056 94.4 5 0.047 95.3 6 0.014 98.6

(57) TABLE-US-00004 TABLE 4 Relative peak area from GC analysis and calculated reduction of dimethyldisulfide Sample no. Relative peak area Calculated odour reduction 1 1 0 2 0.001 99.9 3 0.008 99.2 4 0.004 99.6 5 0.002 99.8 6 0.001 99.9

(58) TABLE-US-00005 TABLE 5 Relative peak area from GC analysis and calculated reduction of isovaleric aldehyde Sample no. Relative peak area Calculated odour reduction 1 1 0 2 0.007 99.3 3 0.023 97.7 4 0.010 99.0 5 0.005 99.5 6 0.002 99.8

(59) As can be seen in tables 3-5, the odour reduction is high both for sample 2, which contains 0.3 g activated carbon and for samples 3-6, which each contain the same amount of activated carbon in odour control materials according to the invention. The examples show that the use of fine powder can be avoided without negative influence of the odour reduction.

(60) The various aspects and embodiments of the invention can of course be modified within the scope of the invention. In order to further illustrate the invention, the following examples are provided, which however not should be interpreted as narrowing the intended scope of protection as defined by the appended claims.