WO2014035327A1

WO2014035327A1 - Absorbent hygiene article with odour control substance and method for producing it

Info

Publication number: WO2014035327A1
Application number: PCT/SE2013/051018
Authority: WO
Inventors: Kent Malmgren; Ulla Forsgren Brusk; Chatrine Stridfeldt; Veronica LOPEZ-DURAN
Original assignee: Sca Hygiene Products Ab
Priority date: 2012-08-31
Filing date: 2013-08-30
Publication date: 2014-03-06
Also published as: WO2014035306A1

Abstract

An absorbent hygiene article such as a sanitary napkin, panty liner, diaper, pant diaper, adult incontinence guard or underlay,, wherein said hygiene article contain an odour control substance in the form of an oxidized lipid. The oxidized lipid has a peroxide value as measured by AOCS Official Method Cd 8-53 between 100 and 1000 meq/kg and contains an antioxidant in an amount of at least 0.15 wt% as calculated on the weight of the oxidized lipid. The article may further contain a surfactant mixed with the lipid.

Description

ABSORBENT HYGIENE ARTICLE WITH ODOUR CONTROL SUBSTANCE AND

METHOD FOR PRODUCING IT

TECHNICAL FIELD

The present invention refers to an absorbent hygiene article such as a sanitary napkin, panty liner, diaper, pant diaper, adult incontinence guard or underlay, said absorbent hygiene article containing an odour control substance in the form of an oxidized lipid. The invention also refers to a method for producing an absorbent hygiene article containing an odour control substance in the form of an oxidized lipid.

BACKGROUND OF THE INVENTION

Odour control has become an important factor in absorbent hygiene articles. Odours occur e.g. as a result of discharges from the wearer of an absorbent hygiene article or as a result of the storage of bodily fluids in the article. These odours can be embarrassing for the wearer of the article. It is important, therefore, to reduce or prevent odours from occurring in absorbent articles while they are being worn.

Examples of odour substances that may occur in absorbent hygiene articles are sulphur compounds, aldehydes, indoles, amines etc. Various methods are used to prevent or reduce odours in absorbent hygiene articles that have arisen in conjunction with the discharge of bodily fluids. The methods are based on 1) masking of the odours; 2) a chemical reaction, for example in the form of neutralization, with an acid/base system; 3) adsorption/absorption of odours involving the creation of surfaces which exhibit a special affinity to the odours or large specific surfaces/cavities which are able to bind the odours concerned and thus to prevent them from remaining in gaseous form, or 4) bacteria inhibitors which reduce/control the growth of bacteria and associated odours that have arisen because of high bacteria counts.

Perfumes or fragrances are used, for example, in order to mask odours. Maskers do not remove the odourss and must be added in an appropriate quantity to ensure that the odour is covered and that the perfume does not smell too strongly. Zeolites, silicone dioxide, clays, active carbon and/or cyclodextrin, for example, are used for the adsorption of odour substances. Some of these are susceptible to moisture, however, which restricts their effectiveness. Sodium bicarbonate, citric acid and/or superabsorbent materials with a low pH are used for the neutralization of certain odours. Bacteria can generate substances with an unpleasant odour, and copper acetate, a superabsorbent material with silver ions and/or an acidic superabsorbent material can be used to reduce the growth of bacteria. The above-mentioned odour control substances are effective against different kinds of odours and act with different mechanisms.

A number of odours are hydrophobic, and such odours are absorbed and/or adsorbed by hydrophobic odour control substances. Hydrophobic odouriferous substances include, for example, certain organic acids, sulphur compounds, aldehydes, indole, amines, etc., which commonly occur in conjunction with the use of absorbent articles.

Described in US 6 147 028 is an odour control substance in the form of polysiloxane- coated starch granules that are used in absorbent products. The starch granules have a hydrophobic surface, and they absorb hydrophobic material from the air. US 6 479 150 describes material layers of thermoplastic fibres with a hydrophobic odour control substance that is modified with a surface-active substance in order to make the layer wettable. The odour control substance is, for example, an aromatic odour control substance. Previously disclosed odour control substances suffer from the disadvantage, among other things, that they are difficult to distribute uniformly throughout the whole of the absorbent product. This is attributable to the fact that previously disclosed odour control materials often consist of solid particles, which cannot be distributed continuously over the internal and external surfaces of the product and as such reduce the degree of coverage. The possibility of trapping undesirable odours in an effective manner is reduced in this way.

GB 1 282 889 discloses a deodourant composition comprising at least one calcium, aluminium, magnesium or zinc salt of an unsaturated aliphatic hydroxycarboxylic acid having at least 17 carbons. It is further told that these metal salts can be combined with saturated aliphatic hydroxycarboxylic acids and unsaturated aliphatic hydroxycarboxylic acids. The saturated hydroxycarboxylic acids may either be naturally saturated or derived from oxidation products of unsaturated fatty acids, such as oleic acid, ricinoleic acid, linoleic acid and linolenic acid. These unsaturated fatty acids upon mild oxidation lead to corresponding pure hydroxycarboxylic acids. Pure hydroxycarboxylic acids have very low oxidizing ability on other substances and a peroxide value close to 0 meq/kg. WO 2008/058565 discloses absorbent articles comprising a peroxy compound as an organic zinc salt, in particular zinc ricinoleate, which are told to have a synergistic effect in the suppression of malodours, such as ammonia.

WO 2009/082287 discloses an absorbent article comprising oxidized lipids as odour control substance. The lipids are oxidized under controlled conditions, e g with ozone, to have a peroxide value of at least 20 meq/kg. WO 2010/039064 discloses a wipe to which has been added an oxidized lipid as odour control substance. The lipids are oxidized to have a peroxide value of at least 20 meq/kg.

The need remains to develop odour control substances for absorbent hygiene products, and one object of the present invention is to develop an absorbent hygiene article comprising an effectively functioning odour control material in the form of an oxidized lipid, wherein the formation of undesired volatile substances caused by decomposition of the oil is reduced or prevented also during long storage periods.

SUMMARY OF THE INVENTION

The above defined problem is solved in the present invention by an absorbent hygiene article such as a sanitary napkin, panty liner, diaper, pant diaper, adult incontinence guard or underlay, said absorbent hygiene article containing an odour control substance in the form of an oxidized lipid, wherein said oxidized lipid has a peroxide value as measured by AOCS Official Method Cd 8-53 between 100 and 1000 meq/kg and contains an antioxidant in an amount of at least 0.15 wt% as calculated on the weight of the oxidized lipid.

The oxidized lipids may have a peroxide value as measured by AOCS Official Method Cd 8-53 of at least 150, preferably at least 200 and not more than 350, preferably not more than 325 meq/kg.

The antioxidant may be an oil soluble antioxidant.

The oil soluble antioxidant may be chosen from vitamin E, gum guaiac, propyl gallate, butylated hydroxyanisol, butylated hydroxytoluene or 2,4,5-trihydroxy hydro-quinone, vitamin K, vitamin A, vitamin D or carotenoids.. Vitamin E exists in eight different forms including four tocotrienols (α, β, γ, δ) and four tocopherols (α, β, γ, δ). Examples of carotenoids are β-carotene, lutein, lycopene. The oxidized lipid may contain at least 0.2 wt% and more preferably at least 0.5 wt% antioxidant

The oxidized lipid may contain up to 5 wt%, preferably up to 3 wt% and more preferably up to 2 wt% antioxidant.

Said absorbent hygiene article may further comprise a surfactant mixed with the oxidized lipid. The amount of surfactant may be between 0.5 and 30 weight% as calculated on the amount of oxidized lipid. The lipids may be fatty acids or derivatives thereof.

The fatty acid derivatives may be esters of fatty acids, especially triglycerides.

At least part of the fatty acids and/or fatty acid derivatives may be unsaturated.

The oxidized lipids may be oxidized by treatment with oxygen

The invention further refers to a method of producing an absorbent hygiene article such as a sanitary napkin, panty liner, diaper, pant diaper, adult incontinence guard or underlay, said absorbent hygiene article containing an odour control substance, said method comprising the steps of oxidizing a lipid so that it will have a peroxide value as measured by AOCS Official Method Cd 8-53 between 100 and 1000 meq/kg, subsequently adding an antioxidant to the oxidized lipid and adding said oxidized lipid containing the antioxidant to said hygiene article or to a component which is to be incorporated in said absorbent hygiene article.

The lipid may be oxidized with oxygen gas.

The lipid may be exerted to UV radiation during oxidation. The antioxidant may be added in an amount at least 0.15 wt% as calculated on the weight of the oxidized lipid.

DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic illustration of the various layers which may be comprised in a hygiene absorbent article such as a sanitary napkin, panty liner, diaper, pant diaper or adult incontinence guard

DEFINITIONS

The term "absorbent hygiene article" refers to an article used for personal hygiene especially for absorbing bodily exudates, like urine, feces and menstrual fluid.. Examples of such absorbent hygiene articles include feminine hygiene products such as sanitary napkins, panty liners and sanitary panties, diapers and pant diapers for infants and incontinent adults, incontinence pads, diaper inserts, underlays and the like. The invention mainly refers to disposable absorbent hygiene articles, which means articles that are not intended to be laundered or otherwise restored or reused after a single use.

The term "lipid" denotes all fat-soluble (lipophilic), naturally-occurring substances, such as fats, oils, waxes, cholesterol, steroids, monoglycerides, diglycerides, triglycerides, phospholipids, and others.

By "oxidized lipids" is meant that the lipids have undergone an oxidation process wherein oxygen has been introduced in the lipid molecular structure. The oxidation agent is any agent, which leads to oxidation of the lipid structure, e.g. oxygen gas, ozone or peroxides.

By "antioxidant" is meant a compound that inhibits the oxidation of other molecules.

Oxidation reactions can produce free radicals and antioxidants have the ability to eliminate such intermediates. DETAILED DESCRIPTION OF THE INVENTION

It has been shown that oxidized lipids, are very effective in reducing certain odouriferous substances which are commonly occurring in absorbent hygiene articles. Natural animal- derived or plant-derived lipids are very often mixtures of mono-, di- and triglycerides and free fatty acids. The lipids can be purified, hydrated, refined, modified and used individually or in different mixtures. Examples of suitable lipids which originate from animals can be found in bees waxes, emu oil, lactis lipida, lanolin, shark's liver oil, lard, whale oil, butter fat and tallow. Examples of suitable lipids which originate from plants can be found in apricot kernel oil, ground nut oil, avocado oil/wax, blackcurrant seed oil, borage seed oil, Brazil nut oil, castor oil, cocoa butter, coconut oil, maize oil, cotton seed oil, rose hip seed oil, evening primrose oil, grape seed oil, linseed oil, mango seed oil, rose oil, olive oil, orange wax, palm oil, ground nut oil, rice wax, sesame seed oil, shea butter, soybean oil, sunflower seed wax, peanut oil, sesame oil, safflower oil, tobaccoseed oil, poppyseed oil, teased oil, kapok oil, rice bran oil, sorghum oil, crambe oil, linseed oil, perilla oil, hempseed oil, tung oil, oiticica oil, palm kern oil, sweet almond oil and wheat germ oil. Further examples of lipids are waxy oils, which are esters of mono-alcohols, for example Jojoba oil, phospholipids etc.

Triglycerides are commonly occurring in many natural fats and oils, such as rapeseed oil, olive oil, maize oil, sunflower oil, palm oil, cocoanut oil and butter, palm oil, cacao butter, theobroma oil etc. Most of the naturally occurring triglycerides contain a mixture of saturated and unsaturated fatty acids, while the proportion of saturated and unsaturated fatty acids varies between the different oils. This proportion is usually given as the quotient: unsaturated/saturated. The unsaturated fatty acids may either be monounsaturated or polyunsaturated. The most commonly occurring fatty acids in triglycerides are palmitic acid, a saturated fatty acid, oleic acid, a monounsaturated fatty acid, linoleic and linolenic acids, which are polyunsaturated fatty acids.

The composition of some common natural oils are given in Table 1 below, which is taken from Bailey^'s Industrial Oil and Fat products, vol.1 , editor: Daniel Swern, John Wiley & Sons Inc., New York, 1979.

Table 1

Saturated fatty acids Unsaturated fatty acids

Vegetable oil (weight-%) (weight-%)

Olive oil 9.3-18.8 81.1-89.0

Sunflower oil 8.7-14.2 85-91

Rapeseed oil 6.2-9.5 90.5-93.8

Maize oil 12-18 82-88

Cocoa butter 59.8 40.2 Such oils and fats normally contain small amounts of antioxidants, either naturally occurring or added by a supplier, so that autoxidation caused by contact with air is substantially prevented or delayed. The lipids used in the present invention are oxidized by an oxidizing agent. Examples of useful oxidizing agents are: oxygen gas, ozone, peroxides, peroxy acids and nitrogen dioxide. The naturally occurring antioxidants will be destroyed during such oxidation (J. Am. Oil Chem. Soc. (2009) 86:895-90; Sabilov et al; Effects of Temperature and UV Light on Degradation of a-Tocopherol in Free and Dissolved Form.

The reactivity of different lipids is dependent on the number of double bonds, i.e. the degree of unsaturation. Saturated lipids oxidize very slowly while lipids with a high degree of unsaturation oxidize more rapidly. The oxidation should be performed under controlled conditions until a desired peroxide value is reached. Preferably the oxidized lipids should have a peroxide value as measured by AOCS Official Method Cd 8-53 between 100 and 1000 meq/kg. The oxidized lipids may have a peroxide value of at least 150 or at least 200 meq/kg. They may further have a peroxide value of not more than 350 or not more than 325 meq/kg.

The lipids may be oxidized by any suitable method and by any suitable oxidation agent, for example by oxygen, ozone, mixtures of ozone/air or ozone/oxygen. The preferred oxidation agent according to the invention is oxygen gas. The lipids may further be exerted to UV-radiation during oxidation with oxygen gas.

At the oxidation process a series of peroxidic products may be formed, such as hydroperoxides, ozonides, diperoxides, peroxides and polyperoxides. Certain by-products may also be formed, for example ketones and aldehydes, which are less desired. These by-products may be removed by washing the lipids with a solvent after the oxidation process. Alternatively volatile undesired substances may be removed by evaporation, for example under vacuum.

Oxidation with oxygen gas instead of ozone reduces the formation of at least some of these undesired by-products. However the problem of autoxidation and/or decomposition of the oxidized lipids during storage remains. Such autoxidation may result in the formation of undesired by-products, such as aldehydes and ketones. These by-products have an unpleasant odour.

Addition of an antioxidant to the oxidized lipids after oxidation will prevent autoxidation and/or decomposition and the formation of such undesired by-products. The antioxidant is preferably oil-soluble. Examples of useful oil-soluble antioxidants are vitamin E, gum guaiac, propyl gallate, butylated hydroxyanisol, butylated hydroxytoluene or 2,4,5- trihydroxy hydro-quinone, vitamin K, vitamin A, vitamin D or carotenoids.. Vitamin E exists in eight different forms including four tocotrienols (α, β, γ, δ) and four tocopherols (α, β, γ, δ). Examples of carotenoids are β-carotene, lutein, lycopene.

The antioxidant should be added to the oxidized lipid in an amount of at least 0.15 wt%, preferably at least 0.2 wt% or more preferably at least 0.5 wt% antioxidant as calculated on the weight of the oxidized lipid. The amount of antioxidant may be up to 5 wt%, preferably up to 3 wt% or more preferably up to 2 wt% antioxidant as calculated on the weight of the oxidized lipid.

The antioxidant that has been tested in the examples below is a-tocopherol. One or more essential oils, such as chamomile, clove, lemon, lavender, rosemary and sandalwood may optionally be added to the oxidized lipid.

The oxidized lipids may thus be added to wood pulp fibres, for example cellulosic fluff pulp, which frequently is used in the absorbent core of a hygiene absorbent article, such as a sanitary napkin, panty liner, diaper, pant diaper, adult incontinence guard or underlay. Alternatively or in addition the oxidized lipids may be added to the topsheet of such an absorbent article or any additional functional layer contained in the absorbent article, such as liquid receiving layer, liquid distribution layer, liquid storage layer etc. The pulp fibres treated with oxidized lipid may be mixed with untreated pulp and/or with superabsorbent material to form an absorbent core. An absorbent core can contain between 0.2 and 50% by weight, preferably between 0.5 and 40% by weight, more preferably between 1 and 35% by weight and most preferably between 3 and 30% by weight of added oxidized lipids calculated on the total weight of the hydrophilic fibres, for example pulp fibres, contained in the absorbent core. In certain areas, for example along the edges of the absorbent core and/or other functional layer of the absorbent article, a higher proportion of the oxidized lipids may be used than in the central area of the absorbent core. The fibres in the edge areas may then be more or less saturated with the oxidized lipids and function as leak barriers.

In garment-like article, such as diapers and pant article the treated fibres can be positioned in a waistband region or in areas around the leg openings. They can then prevent odours from escaping from the article. Alternatively the oxidized lipids can be added to elastic means forming part of for example waist elastics or leg elastics in an absorbent article.

In the same manner as described above with respect to the absorbent core, the oxidized lipids can be uniformly or non-uniformly distributed in any other layer in an absorbent article, such as the topsheet, a liquid receiving layer, a liquid distribution layer or the like. The proportion by weight of the oxidized liquid in these layers can be the same as for the absorbent core.

Other methods for applying the oxidized lipids to a component in an absorbent article are by spraying, coating or impregnation.

Depending on the kind of absorbent article product, the proportion of oxidized lipids will vary. Panty liners, for example, do not require the same quantity of odour control material as an incontinence product.

Odours in absorbent articles differ in respect of their character. In order to achieve an even better odour-controlling effect, other types of odour control materials or odour control substances can also be used in the absorbent articles according to the present invention. These can be acidified cellulose fibres, for example, and/or superabsorbent materials with a low pH. Cellulose fibres can be acidified, for example, by the addition of a buffer/acid. The acidic odour control materials deal with odouriferous substances that are alkaline, for example, such as amines and ammonia. Acidic odour control materials are capable, if added in a sufficient quantity, of lowering the pH and, by so doing, of inhibiting the growth/activity of bacteria which in turn produce substances that are able to contribute to a badodour. Other odour control substances can also be added to the article, for example chitosan, activated carbon, zeolites, clay, silicone dioxides, cyclodextrin, starch-based odour control substances and esters. The esters can be selected from among cyclical esters or esters selected from among isomentyl acetate, isomentyl propionate, isomentyl isobutyrate, isomentyl crotonate and isomentyl butyrate.

As mentioned above essential oils, such as lavender, sandalwood, lemon, chamomile, clove and rosemary oil may be added to the oxidized oil.

The oxidized lipids can be added to the pulp fibres, or other fibres, in conjunction with the production of the fibres or be added in the production apparatus in which the absorbent articles are produced. The presence of oxidized lipids in hygiene absorbent articles may also inhibit the growth/activity of bacteria which in turn produce substances that are able to contribute to a bad odour. The inhibition of growth/activity of unwanted bacteria is also important for hygienic reasons in the urogenital area. Besides the odour and bacteria control effects, the oxidized lipids may also have a skin care effect.

EXAMPLES

Example 1. Oxidation of vegetable oils

200 ml_ of vegetable oil (sunflower oil, corn oil or olive oil) was placed in a beaker of 11 cm, heated and oxygen bubbling through the oil (gas flow=60 l/h), a magnetic stirrer was used in the beaker. Simultaneously, a Mineralight UV Lamp, Model S-68, 220Volts, 50 Hz, 0.65 Amps was used for sample irradiation. The distance between the UV lamp and the oil surface was 5 cm. Depending on the oil, reaction time and temperature for achieving the highest peroxide value change. The results are given in Table 2.

Table 2. Reaction conditions to achieve the highest peroxide value

Vegetable Oil Time (hours) Temperature (°C)

Sunflower Oil 22.1 80

Corn Oil 6.0 110

Olive Oil 24.0 110 The degree of oxidation was tested by determining the peroxide value according to the test method AOCS Official Method Cd 8-53: Peroxide Value Acetic Acid - Chloroform Method. The peroxide value for both the starting oils and the oxidized oils was determined. The results are given in Table 3 below.

Table 3. Peroxide values of native and oxidized oils

Example 2. Analysis of odour reduction

Treatment of pulp with oils

Sheets of fluff-grade bleached sulphate pulp from International Paper, were impregnated with a solution of the tested oil in acetone. To a pulp sheet weighing 4 g was added 1.71 g oil in 1.71 g acetone. The solution was evenly distributed over the surface of the sheets. When the acetone had evaporated, the sheets contained 30 wt% oil and 70 wt% pulp fibers. The sheets were defibrated in an IKA A11 basic Analytical mill to produce fluffed pulp during approximately 1 minute. Following the same procedure pulps with 3 wt% and 10 wt% were prepared. In those cases 0.12 g and 0.44 g of oil were added respectively.

For the experiment four (4) malodour substances were used: dimethyl sulfide (DMS), dimethyl disulfide (DMDS), isovaleraldehyde and diacetyl. Due to the difference between the solubility of the compounds two different solutions were prepared (Solution A and Solution B) ^■ Solution A:

Solution A.1 : In a vial with septum were placed 22,14 g polyethyleneglycol with a molar weight 300 g/mole (PEG300), 115 μΙ_ DMS, 90 μΙ_ DMDS and 5 120 μΙ_ Isovaleraldehyde.

Solution A.2: From solution A.1 were taken 50 μΙ_ and placed in another vial with 22,44 g PEG300.

^■ Solution B:

10 - Solution B.1 : To a 250 ml volumetric flask were added 105 μΙ_ diacetyl using distilled water as solvent.

Solution B.2: From solution B.1 were taken 0,6 ml and placed in a vial with 9,4 ml of distilled water.

15 Odour reduction measurement:

1 g treated pulp was placed in a 60 ml vial, after which 3.9 ml of 0.01 phosphate buffer saline pH 7.4 from Sigma was added with 0.1 mL of the desired odour solution (A.2 or B.2). The final concentrations were 300 ng/ml for dimethyl sulfide (DMS), dimethyldisulfide (DMDS) and Isovaleraldehyde (IVAL), 600 ng/ml for diacetyl.

20 The vial was then placed in an oven and after 3 hours at a temperature of 30°C, after this time a SPME fibre (Supelco), 75 urn Carboxen-PDMS, was injected into the headspace above the pulp and after additional 0.5 h the SPME fiber was analyzed with gas chromatography (GC), Thermo Finnigan Trace, with a MS detector. The chromatographic analysis was carried out on a Termo Finnigan Trace GC with a MS detector. The GC was

25 equipped with a split/splitless injector, mode splitless and 180°C in the transfer line. The column used was a ZB-624 (Zebron),30 m, 0.25 mm i.d, 1.40 μηι film thickness. The MS mode was full scan, when the compounds were analysed the following mass numbers were chosen:

62 for DMS, 58 for IVAL,

30 94 for DMDS, 86 for diacetyl.

The peak area of each odour substance was determined for samples with treated pulp and an untreated reference pulp, results are shown in Table 4. The odour reduction in comparison to untreated pulp was made by equation (1): Odour reduction (% =

l l₀₀%

Peak area of sample with untreated pulp/ J

Table 4. Results odour reduction (%)

Example 3. Preparation of oxidized sunflower oils with different peroxides values

200 ml_ of sunflower was placed in a beaker of 11 cm, heated and gas bubbling through the oil (gas flow=60 l/h), a magnetic stirrer was used in the beaker. Simultaneously, a Mineralight UV Lamp, Model S-68, 220Volts, 50 Hz, 0.65 Amps was used for sample irradiation. The distance between the UV lamp and the oil surface was 5 cm. Different reaction conditions were tested. Sunflower oil was oxidized at different temperatures: 55, 80 and 110 °C. The influence of the bubbled gas was also tested. In this case it was bubbled oxygen, air or no gas bubbling. Results are shown in Table 5. Table 5. Influence of reaction conditions on the peroxide value

Example 4. Tests with different amounts of added oils having different peroxides values

This experiment was made using 3% and 30% addition of the sunflower oil. The different peroxides values were tested, for sunflower oil the peroxides values were: 14, 34, 65, 101 , 235, 324, 363 and 396 meq/Kg. The measurement of peroxide value and the odour characterization was made as described in example 1 and 2. Tables 6 and 7 show the results.

Table 6. % odour reduction after 3wt% addition oxidized sunflower oil

Table 7. % odour reduction after 30wt% addition of oxidized sunflower oil

Example 5. Preparation of oxidized vegetable oils containing a-tocopherol

After completed oxidation an antioxidant in the form of α-tocopherol was added to some of the oxidized oils from Example 1. The following amounts of α-tocopherol were added: 0.15 wt%, 0.5 wt%, 1 wt%. The amounts of α-tocopherol were calculated on the weight of the oxidized oil.

Example 6. Measurements of volatile substances from pulp samples containing oxidized vegetable oils with and without α-tocopherol after different storage times

SPME-GC-MS was used to determine the relative changes in volatiles formed in sunflower oil during the storage. 1 g of oxidized oil was placed into a vial. The SPME needle was pierced through the septum of the sample vial, exposing the fiber to the headspace of the sample for 30 min. This allowed the analytes to reach their near- equilibrium concentration with the active phase of the fiber. Subsequently, the needle was pierced through the inlet septum on the GC injector and the fiber was exposed for 5 min. The MS spectra library was used for identification of the measured compounds.

The analyses were conducted after 0, 2, 4, 8 and 12 weeks of storage in order to study the stability of oxidized sunflower oil. Since the oxidized oils have a variety of volatile compounds, only five of them were chosen. In this way, it is easier to see how the chosen volatile compounds change over time; results are shown in Table 8 and 9.

Table 8. Pulp + 30% oxidized sunflower oil

Table 9. Pulp + 30% oxidized sunflower oil containing 1wt% a-tocopherol

Example 7. Analysis of odour reduction after 12 weeks of storage

It was important to test if oxidized oils containing a-tocopherol were able of reducing odours. In this experiment, the efficiency of oxidized sunflower oil after 12 weeks was also tested. Added levels of a-tocopherolwere 1 %, 0.2% and 0.01 %.

Treatment of pulp with oils

Sheets of fluff-grade bleached sulphate pulp from International Paper, were impregnated with a solution of the tested oil in acetone. To a pulp sheet weighing 4 g was added 1.71 g oil in 1.71 g acetone. The solution was evenly distributed over the surface of the sheets. When the acetone had evaporated, the sheets contained 30 wt% oil and 70 wt% pulp fibers. The sheets were defibrated in an IKA A11 basic Analytical mill to produce fluffed pulp during approximately 1 minute. For the experiment three (3) malodour substances were used: dimethyl sulfide (DMS), dimethyl disulfide (DMDS) and isovaleraldehyde (IVAL)

^■ Solution A:

Solution A.1 : In a vial wih septum were placed 22, 14 g polyethyleneglycol with a molar weight 300 g/mole (PEG300), 1 15 μΙ_ DMS, 90 μΙ_ DMDS and

120 μΙ_ Isovaleraldehyde.

Solution A.2: From solution A.1 were taken 50 μΙ_ and placed in other vial with 22,44 g PEG300. Odour reduction measurement:

1 g treated pulp was placed in a 60 ml vial, after which 3.9 ml of 0.01 phosphate buffer saline pH 7.4 from Sigma was added with 0.1 ml_ of the odour solution. The final concentrations were 300 ng/ml for dimethyl sulfide (DMS), dimethyldisulfide (DMDS) and Isovaleraldehyde (IVAL). The vial was then placed in an oven and after 3 hours at a temperature of 30°C, after this time a SPME fibre (Supeico), 75 um Carboxen-PDMS, was injected into the headspace above the pulp and after additional 0.5 h the SPME fiber was analyzed with gas chromatography (GC), thermo Finnigan Tree, with a MS detector. The chromatographic analysis was carried out on a Termo Finnigan Trace GC with a MS detector. The GC was equipped with a split/splitless injector, mode splitless and 180°C in the transfer line. The column used was a ZB-624 (Zebron),30 m, 0.25 mm i.d, 1.40 μηι film thickness. The MS mode was full scan, when the compounds were analysed the following mass numbers were chosen:

62 for DMS, 58 for IVAL,

94 for DMDS, 86 for diacetyl.

The peak area of each odour substance was determined for samples with treated pulp and an untreated reference pulp, results are shown in Table 10. The odour reduction in comparison to untreated pulp was made by equation (1):

Odour reduction (%) = [l - ( Actual peak area \Λ _{xl Q Q%}

L Peak area of sample with untreated pulp/ J

Table 10. Odour reduction (%) after addition of a-tocopherol and comparison between samples after 0 and 12 weeks

Addition of surfactant Below some examples are given illustrating the effect of adding a surfactant together with the oxidized lipid to fluffed pulp. The oxidized lipid in all examples was oxidized sunflower oil having a peroxide value of 292 meq/kg and it contained 0.5 wt% of an antioxidant in the form of a-tocopherol. Different amounts of non-ionic, anionic and cationic surfactants were added. Example 8. Preparation of fluffed pulp

A pulp sheet with a weight of 3 g was cut from a roll pulp produced by the company International Paper. The sheet was manually torn to pieces and then placed in a kitchen mixer with the trade name Coline. It was then run at maximum speed for about 1 minute and a fluffed pulp was formed.

Example 9. Preparation of oxidized sunflower oil with addition of a- tocopherol

Sunflower oil, COOP Extra, was obtained from a grocer ^'s store and 200 ml of this oil was kept in a beaker with an inner diameter of 11 cm. The temperature was adjusted to 80°C by the aid of an IKA-Combining RET hot plate. The oil was stirred by a magnetic stirrer and about 60 I oxygen was added to the oil per hour. This addition was made by bubbling the gas into the liquid from a glass tube. A Mineralight UV lamp, Model S-68, 220 V, 50 Hz, 0.65 A was used to irradiate the oil with UV light. The distance between the lamp and the oil surface was 5 cm. After UV irradiation and oxygen addition for 22 h, the oil had been oxidized. The peroxide value of the oxidized sunflower oil was determined to 292 meq./kg according to the standard procedure shown in AOCS Official Method Cd 8-53A.

The oxidized sunflower oil was added 0.5 weight % a-tocopherol, delivered by Sigma- Aldrich.

Example 10. Preparation of fluffed pulp with 15 % oxidized sunflower oil

A pulp sheet with a weight of 3 g was cut from a roll pulp produced by the company International Paper. The pulp sheet was added a solution of 0.53 g of the oxidized sunflower oil with 0.5 % a-tocopherol from example 9 in about 1 g acetone. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all acetone was evaporated and then it was manually torn to pieces. These were placed in a kitchen mixer with the trade name Coline. It was then run at maximum speed for about 1 minute and a fluffed pulp was formed. Example 11. Preparation of fluffed pulp with 15 % oxidized sunflower oil and low dosage of non-ionic surfactant

A pulp sheet with a weight of 3 g was cut from a roll pulp produced by the company International Paper. The pulp sheet was added a solution of 0.53 g of the oxidized sunflower oil with 0.5 % a-tocopherol from example 9 and 0.011 g of Triton X-100, delivered by the company VWR, in about 1 g acetone. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all acetone was evaporated and then it was manually torn to pieces. These were placed in a kitchen mixer with the trade name Coline. It was then run at maximum speed for about 1 minute and a fluffed pulp was formed. The dosage of nonionic surfactant was 2 % of the added amount of oxidized oil. Example 12. Preparation of fluffed pulp with 15 % oxidized sunflower oil and high dosage of non-ionic surfactant

A pulp sheet with a weight of 3 g was cut from a roll pulp produced by the company International Paper. The pulp sheet was added a solution of 0.53 g oxidized of the oxidized sunflower oil with 0.5 % α-tocopherol from example 9 and 0.13 g of Triton X-100, delivered by the company VWR, in about 1 g acetone. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all acetone was evaporated and then it was manually torn to pieces. These were placed in a kitchen mixer with the trade name Coline. It was then run at maximum speed for about 1 minute and a fluffed pulp was formed. The dosage of nonionic surfactant was 20 % of the added amount of oxidized oil.

Example 13. Preparation of fluffed pulp with 15 % oxidized sunflower oil and low dosage of anionic surfactant

A pulp sheet with a weight of 3 g was cut from a roll pulp produced by the company International Paper. The pulp sheet into two pieces with the a weight of 1,5 g. To one of these sheets a solution of 0.53 g of the oxidized sunflower oil with 0.5 % a- tocopherol from example 9 was added. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all acetone was evaporated and then it was manually torn to pieces. To the other sheet a solution of 0.011 g sodiumdodecyl sulphare, delivered by the company Sigma Aldrich, in about 2 g distilled water, was added. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all water was evaporated and then it was manually torn to pieces. These pieces from the pulp impregnated with oxidized oil and surfacant were placed in a kitchen mixer with the trade name Coline. It was then run at maximum speed for about 1 minute and a fluffed pulp was formed. The dosage of anionic surfactant was 2 % of the added amount of oxidized oil.

Example 14. Preparation of fluffed pulp with 15 % oxidized sunflower oil and high dosage of anionic surfactant A pulp sheet with a weight of 3 g was cut from a roll pulp produced by the company International Paper. The pulp sheet into two pieces with the a weight of 1,5 g. To one of these sheets a solution of 0.53 g of the oxidized sunflower oil with 0.5 % a- tocopherol from example 9 was added. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all acetone was evaporated and then it was manually torn to pieces. To the other sheet a solution of 0.13 g sodiumdodecyl sulphare, delivered by the company Sigma Aldrich, in about 2 g distilled water, was added. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all water was evaporated and then it was manually torn to pieces. These pieces from the pulp impregnated with oxidized oil and surfacant were placed in a kitchen mixer with the trade name Coline. It was then run at maximum speed for about 1 minute and a fluffed pulp was formed. The dosage of anionic surfactant was 20 % of the added amount of oxidized oil.

Example 15. Preparation of fluffed pulp with 15 % oxidized sunflower oil and low dosage of cationic surfactant A pulp sheet with a weight of 3 g was cut from a roll pulp produced by the company International Paper. The pulp sheet into two pieces with the a weight of 1,5 g. To one of these sheets a solution of 0.53 g of the oxidized sunflower oil with 0.5 % a- tocopherol from example 9 was added. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all acetone was evaporated and then it was manually torn to pieces. To the other sheet a solution of 0.061 g Silastol PHP 26 with a concentration of 18 %, delivered by the company Schill+Seilacher, in about 2 g acetone, was added. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all acetone was evaporated and then it was manually torn to pieces. These pieces from the pulp impregnated with oxidized oil and surfacant were placed in a kitchen mixer with the trade name Coline. It was then run at maximum speed for about 1 minute and a fluffed pulp was formed. The dosage of cationic surfactant was 2 % of the added amount of oxidized oil.

Example 16. Preparation of fluffed pulp with 15 % oxidized sunflower oil and high dosage of cationic surfactant

A pulp sheet with a weight of 3 g was cut from a roll pulp produced by the company International Paper. The pulp sheet into two pieces with the a weight of 1,5 g. To one of these sheets a solution of 0.53 g of the oxidized sunflower oil with 0.5 % a- tocopherol from example 9 was added. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all acetone was evaporated and then it was manually torn to pieces. To the other sheet a solution of 0.72 g Silastol PHP 26 with a concentration of 18 %, delivered by the company Schill+Seilacher, in about 2 g acetone, was added. The solution was distributed as evenly as possible by a pipette on the upper surface of the pulp sheet. The pulp sheet was then stored at room temperature until all acetone was evaporated and then it was manually torn to pieces. These pieces from the pulp impregnated with oxidized oil and surfacant were placed in a kitchen mixer with the trade name Coline. It was then run at maximum speed for about 1 minute and a fluffed pulp was formed. The dosage of cationic surfactant was 20 % of the added amount of oxidized oil.

The non-ionic surfactant Triton X-100 is soluble in acetone and could therefore be mixed with oil + acetone before addition to the pulp. The anionic surfactant sodium dodecyl sulphate is not soluble in acetone and was therefore added in the form of a water solution to half of the amount of pulp. To the other half amount of pulp the oil + acetone was added. The two treated pulp sheets were combined as disclosed above in Examples 12 and 13. The addition of the cationic surfactant SILASTOL PHP 26 was made in a corresponding way as for the anionic surfactant. The effect of addition of surfactant on penetration of the oil into the pulp was visually significant. When only oil in acetone was added the distribution of the liquid was poor and there were initially dry zones in the sample. When a surfactant was added the distribution of the liquid (oil + acetone + surfactant) in the sample was much improved.

Tests with respect to odour reduction were performed for all samples according to Examples 8-15 and the result is shown in Table 11 below. The tests were performed according to the method disclosed in Example 2. Table 11 gives the results as relative concentrations of DMS, IVAL and DMDS in % in the samples with respect to the untreated reference sample (Example 8).

Table 11. Odour reduction (%) with and without surfactant

DMS IVAL DMDS

Ref. Untreated pulp (Ex. 8) 0 0 0

Example 9 (without surfactant) 99.7 83.3 67.7

Example 1 1 (with 2% non-ionic surfactant) 99.7 92.7 91.3

Example 12 (with 20% non-ionic surfactant) 99.4 89.6 81.6

Example 13 (with 2% anionic surfactant) 99.8 86.1 78.9

Example 14 (with 20% anionic surfactant) 100 98.2 98.3

Example 15 (with 2% cationic surfactant) 99.9 93.2 93.2

Example 16 (with 20% cationic surfactant) 99.9 91.3 93.5

The results show that the addition of surfactant did not have any negative influence on the odour reduction. There was rather a positive influence, which may be due to an improved distribution of the oxidized oil in the samples.

EMBODIMENTS OF PRODUCT CONCEPTS

Below some examples will be given of concepts of hygiene articles comprising oxidized lipids as odour control substance. Reference is made to Figure 1 illustrating the various layers that may be comprised in a hygiene absorbent article like a sanitary napkin, panty liner, diaper, pant diaper or adult incontinence guard.

The hygiene absorbent article usually comprises a liquid-pervious topsheet 1 , a liquid impermeable backsheet 2 and an absorbent core or storage layer 3 disposed

therebetween. The liquid impermeable backsheet 2 may be moisture vapour permeable. A liquid acquisition layer 4 may be located between the topsheet 1 and the absorbent core/storage layer 3. In one embodiment an additional layer 5 of absorbent material is located between the liquid acquisition layer 4 and the absorbent core/storage layer 3. This additional layer 5 may be impregnated with an oxidized lipid containing an antioxidant according to the invention and optionally also comprising a surfactant. Said additional layer 5 comprising oxidized lipid as odour control agent may, for example, be a tissue paper, a foam layer, a nonwoven layer or an airlaid tissue layer.

Optionally a film 6 of water soluble polymer, for example polyethylene oxide, polyvinyl alcohol, polysaccharide such as modified starch, sugar or sugar alcohol, polyacryl amide, polyvinyl amine, polyvinyl pyridine, polyvinyl pyrrolidone, or a mixture thereof, may be disposed between said additional layer 5 comprising the oxidized lipid and the absorbent core 3 in order to prevent migration of the oxidized oil to the absorbent core/storage layer 3. The film 6 will be dissolved when the hygiene article is wetted by body fluid. The film layer 6 can be excluded. If no surfactant is present in the additional layer 5 comprising oxidized lipid said layer 5 may, due to the hydrophobic nature of the oxidized lipid, be provided with apertures or cuts to secure rapid passage of body fluid to the underlying absorbent core/storage layer 3. In another embodiment the liquid acquisition layer 4 is treated with oxidized lipid containing an antioxidant according to the invention and optionally also a surfactant. The liquid acquisition layer 4 may be treated with the oxidized lipid and optional surfactant on the garment facing side only. The additional layer 5 may in this embodiment be absent. A film layer 6 of water soluble polymer may optionally be disposed between the liquid acquisition layer 4 treated with oxidized lipid and the absorbent core/storage layer 3. The film layer 6 can be excluded.

If no surfactant is present in the acquisition layer 4 comprising oxidized lipid said layer 4 may, due to the hydrophobic nature of the oxidized lipid, be provided with apertures or cuts to secure rapid passage of body fluid to the underlying absorbent core/storage layer 3.

In a further embodiment the absorbent core/storage layer 3 contains oxidized lipid containing an antioxidant according to the invention and optional surfactant. The absorbent core/storage layer 3 may comprise between 10 and 15% by weight oxidized lipids calculated on the total amount of hydrophilic fibres, for example pulp fibres, contained in the absorbent core/storage layer 3. In a still further embodiment the oxidized lipid is disposed in the tophseet 1. The topsheet 1 may comprise an apertured polymeric film which on the wearer-facing side is laminated to a nonwoven layer. A tissue paper impregnated with the oxidized lipid containing an antioxidant according to the invention and optionally a surfactant is laminated to the garment facing side of the aperture film.

An acquisition layer 4 and optionally a water soluble polymeric film 6 may be disposed between the multilayer topsheet 1 and the absorbent core/storage layer 3.

The oxidized lipid may in addition to the antioxidant contain further additives, for example essential oils. It may also contain a viscosity increasing agent, for example petrolatum, in order to reduce migration of the lipid in the structure. Examples of other viscosity regulating agents are polyethylene glycol (PEG) and glycerol. Petrolatum will dissolve in the lipid, while polyethylene glycol (PEG) and glycerol will give two phases when added to the lipid, e g oil, and the possibility to create an emulsion.

Claims

An absorbent hygiene article such as a sanitary napkin, panty liner, diaper, pant diaper, adult incontinence guard, or underlay, said absorbent hygiene article containing an odour control substance in the form of an oxidized lipid characterized in that said oxidized lipid has a peroxide value as measured by AOCS Official Method Cd 8-53 between 100 and 1000 meq/kg and contains an antioxidant in an amount of at least 0.15 wt% as calculated on the weight of the oxidized lipid.

An absorbent hygiene article as claimed in claim 1 , characterized in that the oxidized lipids have a peroxide value as measured by AOCS Official Method Cd 8-53 of at least 150, preferably at least 200 and not more than 350, preferably not more than 325 meq/kg.

3. An absorbent hygiene article as claimed in claim 1 or 2, characterized in that the antioxidant is an oil soluble antioxidant.

An absorbent hygiene article as claimed in claim 3, characterized in that the oil soluble antioxidant is chosen from vitamin E, gum guaiac, propyl gallate, butylated hydroxyanisol, butylated hydroxytoluene or 2,4,5-trihydroxy hydro- quinone, vitamin K, vitamin A, vitamin D or carotenoids.

An absorbent hygiene article as claimed in claim 4, characterized in that the oil soluble vitamin is a-tocopherol.

An absorbent hygiene article as claimed in any of the preceding claims, characterized in that the oxidized lipid contains at least 0.2 wt% and more preferably at least 0.5 wt% antioxidant.

7. An absorbent hygiene article as claimed in claim 6, characterized in that the oxidized lipid contains up to 5 wt%, preferably up to 3 wt% and more preferably up to 2 wt% antioxidant.

8. An absorbent hygiene article as claimed in any of the preceding claims, characterized in that said absorbent hygiene article further comprises a surfactant mixed with the oxidized lipid.

9. An absorbent hygiene article as claimed in claim 8, characterized in that the amount of surfactant is between 0.5 and 30 weight% as calculated on the amount of oxidized lipid.

10. An absorbent hygiene article as claimed in any of the preceding claims, characterized in that the lipids are fatty acids or derivatives thereof.

1 1. An absorbent hygiene article as claimed in claim 10, characterized in that the fatty acid derivatives are esters of fatty acids, especially triglycerides.

12. An absorbent hygiene article as claimed in claiml O or 1 1 , characterized in that at least part of the fatty acids and/or fatty acid derivatives are unsaturated.

13. An absorbent hygiene article as claimed in any of the preceding claims, characterized in that said oxidized lipids are oxidized by treatment with oxygen.

14. A method of producing an absorbent hygiene article such as a sanitary napkin, panty liner, diaper, pant diaper, adult incontinence guard or underlay, , said absorbent hygiene article containing an odour control substance as claimed in any of claims 1-1 1 , characterized in oxidizing a lipid so that it will have a peroxide value as measured by AOCS Official Method Cd 8-53 between 100 and 1000 meq/kg, subsequently adding an antioxidant to the oxidized lipid and adding said oxidized lipid containing the antioxidant to said hygiene article or to a component which is to be incorporated in said hygiene article.

15. A method as claimed in claim 14, characterized in oxidizing the lipid with oxygen gas.

16. A method as claimed in claim 14 or 15, characterized in exerting the lipid to UV radiation during oxidation.

17. A method as claimed in any of claims14-16, characterized in adding the antioxidant in an amount of at least 0.15 wt% as calculated on the weight of the oxidized lipid.

18. A method as claimed in any of claims 14-17, characterized in adding a

surfactant to the oxidized lipid.

19. A method as claimed in claim 18, characterized in adding the surfactant in an amount between 0.5 and 30 weight% as calculated on the amount of oxidized lipid.