Pulp for Odor Control

Abstract

A wood pulp useful for odor control in absorbent products. It incorporates a biocide or a biocide and essential oils.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is entitled to and claims the benefit of priority under 35 U.S.C. §119 from U.S. Provisional Patent Application Ser. No. 61/218612 filed Jun. 16, 2009, and titled “PULP FOR ODOR CONTROL” the contents of which are incorporated herein by reference.

This application is directed to pulps containing additives which will reduce the odor in absorbent products.

Odor has always been a problem with absorbent garments such as diapers, adult incontinent products and feminine hygiene products. Each of these products is designed to contain body or physiological waste materials. These may take the form of fluids or excrement. There are odors associated with these waste materials and there is a long history of attempts to mask these odors. Most of these attempts have been to apply additives to the products.

It would be advantageous to provide a pulp treated with an additive which would mask or reduce a variety of odors which emanate from body or physiological waste materials. This would treat the absorbent product without the need for treatment of individual converted products.

It has been discovered that pulp treated with certain additives can be used to mask or neutralize odors that originate in body waste material. The additives are biocides or a combination of biocides and essential oils. The pulp can be treated at the pulp manufacturing plant and provided to the absorbent manufacture for incorporation into the absorbent product. The pulp comes into contact with the body waste material so there can be interaction between the additives and the body waste material.

Absorbent hygienic products employing fiberized wood pulp have been available for many years. However, the tonnage used for this purpose was relatively modest until the advent of disposable diapers, first for infants and later for incontinent adults. The advent of these products and their worldwide use created an explosion in demand. The basic product leaving the pulp mill is most usually termed a “fluff pulp”. In the United States it is most typically a fully bleached southern pine kraft process pulp produced in relatively heavy caliper, high basis weight sheets. The product is rewound into continuous rolls for shipment to the customer. Since the rolled product is intended to be later reprocessed into individual fibers, low sheet strength is desirable and typically little or no refining is used prior to sheeting. The requirements for surface uniformity and formation are similarly moderate.

The pulp products of the present invention are clearly differentiated from products intended as letter, book, magazine, or similar papers. These are usually relatively highly refined to develop web strength and most have basis weights under about 100 g/m². Some specialty papers, such as cover stocks, may have basis weights that are significantly higher. Good strength is essential. Papers are normally sized to improve ink holdout and other printing properties. The products of the present invention are unsized and the strength properties such as tensile, burst, and tear strength, which are considered essential in papers, are generally much lower.

The basis weight of the products of the present invention may be as low as about 250 g/m² and are preferably at least about 550 g/m² and are typically in the range of 680 g/m² to 800 g/m². The fiber will most usually be unrefined or only lightly refined although the invention is not so limited. Where a high surface area product is desired the fiber will normally be significantly refined. Although some cellulose wood pulps may contain fillers, these pulps do not contain fillers.

The cellulose pulp of the invention may be made using conventional kraft, sulfite, chemithermomechanical or other well known processes. The furnish can be from any of various cellulose containing raw materials. Most usually these will be deciduous hardwoods; coniferous species, usually termed softwoods; or mixtures of these materials. A preferred pulp is a bleached softwood kraft pulp that would normally be intended for ultimate use as absorbent fluff. While so-called “dissolving pulps” may be used these are not preferred because of their low yield and resultant much greater cost.

Typically, in pulp sheet manufacturing wood chips are digested with chemicals to form cellulosic wood pulp fibers which can then be washed and bleached if desired. The fibers are then formed into an aqueous slurry which is deposited on a wire from a source, such as a headbox, dewatered and formed into a web or sheet of fibers and the fiber sheet is dried. The sheet or mat is formed by a wet laying process. The fibers have a hydrogen bonding capability which allows them to bond together in a wet laying process.

The pulp slurry is delivered from a headbox onto a Fourdrinier wire. Water is drawn from the pulp deposited on wire by conventional vacuum system leaving a deposited pulp sheet which is further dewatered by pressure rolls. The pulp sheet is then dried and then rolled up into a roll for shipment. The roll may have a moisture content of no more than 10% by weight of the fibers and usually no more than about 6% to 8% by weight. By wet forming is meant preparation of the sheet or web from a suspension of pulp fibers in water by conventional papermaking techniques.

At the customer's plant, the rolls are continuously fed into a device, such as a hammermill, to be reduced as much as reasonably possible to individual fibers. The fiberized product is generally termed a cellulose “fluff”. This is then continuously air laid into pads for inclusion in the intended product. U.S. Pat. No 3,975,222 to Mesek is exemplary of such a process.

The fibers are formed into the core of a disposable diaper, disposable incontinent product or feminine hygiene product. These products will usually have a top sheet through which urine or menstrual fluid will flow, a core material, and a fluid impermeable back sheet. The core material may be of one or more layers. It can have an acquisition layer, a distribution layer and a storage layer. The layers may have different amounts and types of fibers. Each of the layers will have the individualized pulp fibers along with other material such as cross-link cellulose fibers, and superabsorbent particles. U.S. Pat. No. 6,436,418 describes a disposable diaper having certain features.

The pulp is treated with the additive material either at the wet end by addition of the additives into the head box before formation of the pulp sheet to incorporate the additives into the pulp sheet, or by applying the additives to the formed pulp sheet either before or after the pulp sheet is dried.

The additives can be biocide or biocide and essential oils.

Biocides that can be used are quaternary amines such as benzalkonium chloride, benzethonium chloride, methylbenzethonium chloride, cetalkonium chloride, cetylpyridinium chloride, cetrimonium, cetrimide, dofanium chloride, tetraethylammonium bromide, didecyldimethylammonium chloride and domiphen bromide; Isothiazolones such as methylisothiazolinone, chloromethylisothiazolinone, benzisothiazolinone, octylisothiazolinone, and dichlorooctylisothiazolinone; biguanides such as polyaminopropyl biguanide; and triazoles such as propiconazole and tebuconazole.

The biocide is a stable suspension with the active component being 10% to 30% of the weight of the total suspension. In one embodiment it is approximately 20% of the weight of the suspension. If the biocide is used by itself then the suspension can be applied in amounts from 0.05 to 2.5% by weight on oven dry pulp. In one embodiment the suspension is used in a range of 0.25% to 0.32% by weight on oven dry pulp. If the suspension is used at 0.25% then the active ingredient is at 0.05% by weight on oven dry pulp. The active ingredient, if the biocide is used by itself, can be in the range of 0.01% to 0.5% of the weight of the oven dry pulp.

If the biocide is used with an essential oil then the amount of biocide can be less. When used with the essential oil the biocide suspension would be used in a range of 0.1 to 0.2% by weight of the weight of the oven dry pulp. In one embodiment the suspension would be used in a range of 0.12 to 0.13%. If the amount of suspension is 0.125% then the amount of active ingredient is 0.025%. When used with essential oils the amount of active ingredient is usually 0.005 to 0.05%.

Examples of essential oils that can be used are: ajowan, angelica root, angelica root himalayan, angelica seed, aniseed china star, anise seed, aniseed, armoise, artemisia, asafoetida, backhousia anisata, lemon myrtle oil certified, basil, basil australian, basil sweet linalool, basil methyl chavicol, bay west indies, bergamot calabrian, bergamot ivory coast, bergamot mint, bergamot non-phototoxic, borneo camphor, buchu, cabreuva, cajeput ambon, camphor white oil, cananga, caraway, cardamon, carrot seed, carrot seed european, cassia, cedarwood atlas, cedarwood chinese, cedarwood himalayan, cedar leaf, cedarwood texas, cedarwood virginian, celery seed, chamomile german extra blue, chamomile wild moroccan, chamomile matricaria, chamomile roman, cinnamon bark, cinnamon leaf, cistus, citronella ceylon, citronella java, clary sage french, clary sage bulgarian, clary sage, clove bud, clove bud madagascar extra, clove leaf, clove stem, copaiba, coriander, cubeb, cumin, cypress provence, cypress wild, cypress white wood, dill seed, elemi, eremophila, buddawood, eucalyptus australiana, eucalyptus blue mallee bush still, eucalyptus blue gum, eucalyptus dives “c”, eucalyptus radiata, eucalyptus staigeriana, everlasting oil, fennel sweet, fennel wild tasmanian, fir needle, siberian, fir needle, canada, fir needle, silver, frankincense, frankincense somalia, galbanum, garlic, geranium, geranium bourbon reunion, geranium bourbon china, geranium egyptian, ginger, ginger fresh, grapefruit australian, grapefruit pink, guaiacwood, gurjun balsam oil, ho leaf, hyssop, juniper branch, juniperberry extra, juniperberry wild himalayan, juniperberry wild tyrol, kanuka, laurel leaf, lavender, lavender french alpine, lavandin, lavender bulgarian, lavender french population, lavender true oil, lavandid absolute, lavender spike spanish, lavender tasmanian, lemon cold pressed, lemongrass cochin, lemongrass guatemalan, lemongrass nepal, lemon scented eucalyptus, lemon scented tea tree, lemon verbena genuine, lime cold pressed, lime distilled, lime west indian distilled, litsea cubeba, lovage root, mace east indian, mandarin cold pressed, mandarin australian, cold pressed, mandarin sicilian premium, manuka, marjoram majorana, marjoram spanish, melaleuca ericifolia, melissa genuine, melissa oil, melaleuca quinquenervia linalool, melaleuca quinquenervia nerolidol, myrrh, myrtle dalmation, nagarmotha, neroli bigarade, niaouli pacific islands, niaouli australian, nutmeg, olibanum, orange bitter, orange navel, orange sweet, orange valencia, origanum, palmarosa, parsley herb, parsley seed, patchouli, patchouli aceh, patchouli clear, pennyroyal, peppermint arvensis complete, peppermint australian, peppermint eucalyptus, peppermint mitcham, pepper black, peppermint yakima, peru balsam oil, petitgrain bigarade, petitgrain bigarade italian, petitgrain mandarin, petitgrain paraguay, pimento leaf, pine needle, pine extract, pine white, austrian, pinus pumilio, pinus sylvestris, rose otto bulgarian, rose otto moroc, rose otto turkish, rosemary, rosemary verbenone australian, rosemary moroccan, rosemary spanish, rosemary tunisian, rosemary verbenone oil, rosewood brazilian sustainable, sage dalmatian, sage spanish, sandalwood east indian, sandalwood west indian, sandalwood pacific islands, sandalwood west indian, sandalwood western australian, savory summer, savory winter, spearmint, spearmint premium mid west, spikenard, tagette, tagetes, tangerine, tarragon, tea tree bush still, tea tree oil certified, tea tree premium, thuja, thyme red, thyme linalool oil, thyme thymol oil, thyme wild, tocopherol alpha, turmeric, turpentine, valerian european, valerian indian, vanilla, vetiver, vetiver bourbon, vetiver haiti, vetiver java, wintergreen natural chinese, wintergreen natural gaultheria, yarrow, yarrow high chamazulene ct, ylang ylang 1st, ylang ylang 3rd, ylang ylang complete, ylang ylang extra, ylang ylang super extra.

Similarly, essential oil components that reduce odors such as ammonia, sulfur and mercaptans can be readily selected. Where a broad spectrum of odors is to be treated, a broad-spectrum mix of essential oils and/or essential oil components can be used, thus combining the reactivity of a number of components.

One broad spectrum mixture of components and/or essential oils and includes:

Oil/terpene       Concentration range (%)
Rosemary oil      10-20
Cedarwood oil     8-12
Pine Needle oil   20-30
Eucalyptus oil    10-20
Clove oil         5-10
Thyme oil         8-12
Vetiver oil       1-6
Vanilla oleoresin 1-6
Lavender oil      5-10
Tea Tree oil      3-7

Another odor reducing additive includes:

Oil/terpene    Concentration range (%)
α-pinene       2-7
β-pinene       2-7
d 3 carene     2-7
dipentene      15-25
p-cymene       5-15
cineole        5-15
camphor        10-20
terpineol      7-13
bornyl acetate 2-6
cedrene        2-6
cedrol         5-10
thymol         2-16

The essential oils should be diluted in a vegetable based carrier oil. The essential oil is 10% or less of the total weight of the blend of essential oil and carrier oil. Usually the essential oil is from 0.5% to 3% of the weight of the blend of essential oil and carrier oil. The carrier oil should not have any odor of its own. Standard carrier oils are almond oil, grapeseed oil, hazelnut oil and olive oil.

The essential oil can also be diluted in a water emulsion. Again, the essential oil is 10% or less of the total weight of the blend of essential oil and water emulsion. Usually the essential oil is from 0.5% to 3% of the weight of the blend of essential oil and water emulsion.

In one embodiment the amount of essential oil emulsion used in conjunction with biocides was 0.1 to 0.2% of the weight of the pulp In another embodiment the amount of essential oil emulsion was 0.12% to 0.13% of the weight of the pulp. In one embodiment the amount of essential oil on pulp is 0.002 to 0.05% of the weight of the pulp. In another embodiment the amount of essential oil on the pulp is 0.004 to 0.01% of the weight of the pulp.

In a panel test panels of people were asked to rate the odor of samples after the odiferous material had been on the sample for 4 hours and after the odiferous material had been on the sample for 12 hours.

In each of the tests the samples were treated with human urine inoculated with bacteria for the odor. The samples were incubated at body temperature for 4 hours and for 12 hours. The control had no treatment.

One set of samples was treated with a biocide only. The biocide was 1,2-benzisothiazolein-3-one and was applied in suspension in amounts of 0.25, 0.30 and 0.32% by weight of the weight of the pulp. The biocide was 20% of the weight of the suspension.

The panel results are:

Biocide amount	4 hour preference		12 hour preference
% on pulp	Control	Biocide	Control	Biocide
0.25	23	41	17	47
0.30	8	12	5	15
0.32	6	8	7	7

There was a preference for the biocide treated sample over the control samples.

A statistical analysis, using both the normal approximations test and Fisher's exact test indicated there was no significant statistical difference in the panel preferences among the three biocide dosages at either 4 hours or 12 hours.

Another set of samples was treated with biocide and essential oils. The biocide was 1,2-benzisothiazolein-3-one and was applied in suspension in amounts of 0.125 to 0.25% by weight of the weight of the pulp. The biocide was 20% of the weight of the suspension. The essential oil was EcoSorb 606. The suspension was applied in the amount of 0.125% by weight of the pulp. The essential oil was 3% by weight of the suspension. The control had no treatment. The samples were treated with human urine inoculated with bacteria for the odor.

The panel results were:

Biocide +
essential oil	4 hour preference	12 hour preference
% on pulp	Control	Biocide & oil	Control	Biocide & oil
0.125 + 0.125	12	32	6	38
0.25 + 0.125	5	19	5	19

There was a preference for the biocide and essential oil treated samples over the control sample.

A statistical analysis, using both the normal approximations test and Fisher's exact test indicated there was no significant statistical difference in the panel preferences between the two biocide dosages at either 4 hours or 12 hours

The panel preferences of the biocide alone and the biocide with essential oil were compared and it was found the panels did prefer the biocide with essential oil at both 4 and 12 hours by a significant statistical difference.

The results were:

	4 hour preference	12 hour preference
		biocide +		biocide +
	biocide	essential oil	biocide	essential oil
preferred	61	51	69	57
not preferred	37	17	29	11

These numbers show a clear preference for the biocide and essential oil over the biocide alone.

Claims

1. A cellulosic wood pulp comprising a wet formed wood pulp sheet having from 0.01 to 0.5% biocide by weight of the air dry pulp.

2. The wood pulp of claim 1 wherein the biocide is selected from benzalkonium chloride, benzethonium chloride, methylbenzethonium chloride, cetalkonium chloride, cetylpyridinium chloride, cetrimonium, cetrimide, dofanium chloride, tetraethylammonium bromide, didecyldimethylammonium chloride and domiphen bromide, Isothiazolones, methylisothiazolinone, chloromethylisothiazolinone, benzisothiazolinone, octylisothiazolinone, dichlorooctylisothiazolinone; biguanides, polyaminopropyl biguanide, triazoles, propiconazole or tebuconazole.

3. The wood pulp of claim 1 wherein the biocide is 1,2-benzisothiazolein-3-one.

4. The wood pulp of claim 1 further comprising an essential oil in the amount of 0.002 to 0.05% of the weight of the pulp.

5. The wood pulp of claim 4 wherein the essential oil is in an aqueous emulsion.