NO863637L - WATERWARE SHEET FOR DELIVERY OF TOEYWASH ADDITIVES, AND PROCEDURE FOR THE PREPARATION OF SUCH ADDITIVE PRODUCT. - Google Patents

Description

This invention relates to a polymeric sheet or carrier material which is able to store and deliver corrosive additives for laundry to a washing device. It relates - in particular - to a storage-stable sheet for packaging additives for laundry which are soluble in aqueous solutions or solutions of synthetic detergents.

It has long been desired to provide a simple aid adapted to allow the pre-packaging of a desired amount of additives for laundry and to deliver such additives to a washing machine or other water for laundry by simple addition of a package formed by this aid to laundry the facility. Typical additives for washing machines include corrosive bleaches, enzymes, fabric softeners, fabric conditioners, wrinkle-inducing additives, and additives to provide a special feel or "grip." for laundry and synthetic detergents. Since many such additives are not compatible with the skin and degrade during storage without protection, there has been a persistent problem in storing such additives and in

put them in a washing machine or similar.

It has been proposed to use packages comprising water-soluble bags containing synthetic detergents for use in washing clothes. Such bags are particularly attractive for home use where a measured amount of laundry additive, such as a bleach or synthetic detergent, can be added directly into a washing machine without spillage or spillage. Such packages are intended to provide the required amount of laundry additive for a single load of this machine.

So far, however, such packages or other delivery systems have not proven to be completely satisfactory. The difficulties in producing satisfactory packages have frustrated those skilled in the art for many years. Sheet material to carry a laundry additive must simultaneously satisfy many conflicting requirements. The material must form a self-supporting film that quickly dissolves or disperses in washing water at temperatures that are typically from approx. 15.5 to 60°C.

It is proposed in, for example, US patent 3 322 6 74 to use polymer materials which have water-solubilizing groups or hydrophilic groups for this purpose. However, such soluble film-forming materials, such as poly(vinyl alcohol) or cellulose derivatives, were found to be oxidized by and rendered insoluble by strong laundry additives such as chlorine bleaches. Consequently, it has been proposed to use a barrier coating on the inside surface of the laundry package to protect the package material from the chlorine bleach. However, such packages have not been satisfactory since the barrier coatings, upon prolonged storage, tend to break or tear and allow the bleaching agent to contact the package material. After prolonged contact, the packing material oxidizes and becomes water-insoluble and the chlorine bleach loses its activity.

Conventional solution polymers that provide high water solubility and contain 25-50% alkali-soluble monomers were once considered unsuitable as laundry packing materials. Films formed from such polymers are usually hygroscopic and, upon storage at relatively high humidity, tend to lose dimensional stability and become unduly tacky. Moreover, at the low temperatures and low relative humidity often encountered during storage, such films are prone to becoming unduly brittle. Rolls of tear-off packages formed from such sheet material cannot therefore be easily separated by tearing. Furthermore, conventional water-soluble polymers often lose their flexibility during storage at low temperatures of -17.7°C or lower. With the present invention, these difficulties are overcome, and they remain relatively stable under these conditions.

Other water-soluble film-forming materials, such as cellulosic materials, are not easily formed into sheets and cannot be easily closed by heat. It can therefore be difficult and time-consuming to utilize such materials economically.

The purpose of this invention is to provide a polymeric carrier in sheet form which is capable of retaining a pre-selected amount of reactive additive for laundry, which carrier is inert and stable to said additive during storage.

The present invention provides a water-soluble sheet for dispensing additives for laundry which is characterized as a self-supporting film of an addition polymer formed by: (a) from approx. 0 to 85% by weight of a water-insoluble soft monomer, (b) from approx. 15 to 100% by weight of a water-soluble anionic monomer, (c) from approx. 0 to 25% by weight of a water-soluble nonionic monomer and (d) from about 0 to 40% by weight of a water-insoluble hard monomer,

where said addition polymer is neutralized up to approx. 100% with a group IA metal base or a salt of a group IA metal base.

The water-soluble sheet according to this invention will easily dissolve or disperse in aqueous solutions or solutions of synthetic detergent at temperatures from approx. 15.5 to approx. 60°C.

The sheet has sufficient strength to withstand the harshness of mechanical packaging processes, but it still retains sufficient flexibility so that it can be handled without hasty breakage or crumbling. The sheet also resists the destabilizing effects of high humidity. Furthermore, the sheet is resistant to brittleness at low relative humidity or at low temperatures.

The addition polymer is neutralized up to 100% of theory using a group IA metal base or a salt of a group IA metal base, when anionic monomer is present in amounts of 15 to 100%. The polymer has a molecular weight of at least 25,000, preferably above 50,000, and most preferably above 100,000.

It has been found that such acrylic polymers have unusual stability towards reactive additives for laundry, including especially chlorine bleaches. Such polymers also have sufficient mechanical strength to be mixed into sheets for laundry products, and they can be mixed so that they retain their integrity over wide temperature and humidity ranges.

The polymers according to the invention are easily produced by conventional free radical polymerization. Sheets formed from acrylic polymers are easily heat-sealed to provide shelf-stable products. Moreover, the polymer sheet is not substantive to conventional fibers and is inert to conventional laundry additives.

A laundry product is provided which has a particulate laundry additive carried in the sheet according to the invention, or the laundry product may be a quantity of small wafers distributed in the sheet. In one aspect, the product is a uniformly dispersed particulate layer of laundry additive contained in a unit formed by the sheet of the invention, and in others it occupies the wafers in the sheets. For example, the product is manufactured by forming a unit including a dispersed layer of laundry additive and at least one sheet according to the invention, and then closing the unit.

Since the sheet formed by the laundry product contains the bleach as physically separated particles, or wafers, this invention provides the following advantages over water-soluble bags:

(1) clumping of the active ingredient is not possible,

(2) there may be more regulated measurement of the dissolving bleach, and

(3) stain damage to the fabric is reduced to a minimum.

For the addition polymers according to the invention, a soft, water-insoluble monomer is used. Suitable polymerizable monomers that form soft, water-insoluble polymers in the presence of free radical catalysts include primary and secondary alkyl acrylates having alkyl substituents of up to 18 or more carbon atoms, and primary or secondary alkyl methacrylates having alkyl substituents of 5 to 18 or more carbon atoms or other ethylenically unsaturated compounds that are polymerizable with free radical catalysts to form soft, solid polymers. Other typical soft monomers according to the invention include: vinyl esters of saturated monocarboxylic acids, olefin monomers such as ethylene and propylene, and conjugated dienes that form rubbery latexes such as butadiene, chloroprene, isobutene and isoprene.

The preferred soft monomers include alkyl acrylates in which the alkyl group has from 1 to 8 carbon atoms and alkyl methacrylates in which the alkyl group has from 5 to 18 carbon atoms. Examples of such compounds include: amyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, n-amyl methacrylate, hexyl methacrylate, octyl methacrylate, dodecyl methacrylate and such acrylates or methacrylates having substituted alkyl groups, such as butoxyethyl acrylate or methacrylate.

The best results are obtained with, and consequently it is particularly preferred to use, alkyl acrylates in which the alkyl group has from 1 to 4 carbon atoms. Typical compounds include: methyl acrylate, ethyl acrylate, propyl acrylate and butyl acrylate, and preferably butyl acrylate.

The water-soluble anionic monomer which is combined with the water-insoluble soft monomer to form an addition polymer of the invention includes monomers having water- or alkali-solubilizing anionic functionalities, including carboxyl groups, sulfonic acid groups, sulfate groups, phosphate groups, and the like. If desired, monomeric precursors such as acrylamides, maleic anhydride, acrylic esters, acrylic nitrite and the like can be used in the addition reaction under conditions where they form ionizable groups, such as carboxyl groups, in the copolymer.

Carboxylic acid containing monomers are preferred and include: maleic acid, fumaric acid, β-carboxyethyl acrylate, itaconic acid and the like. The best results are obtained with methacrylic acid or acrylic acid, and it is therefore preferred to use these as the anionic monomer.

A preferred addition polymer includes an acrylic copolymer formed from a water-insoluble soft monomer such as methyl acrylate, ethyl acrylate or butyl acrylate and an anionic monomer selected from methacrylic acid, acrylic acid or maleic acid.

The water-soluble nonionic monomer of the invention is used, when desired, to increase the solubility of the polymer and allow a reduction in the amount of anionic functionality present in the polymer. Accordingly, monomers for providing increased water solubility but free of ionizable functionalities include hydroxyalkyl acrylates and methacrylates containing an alkylene group having from 2 to 6 carbon atoms to which the hydroxy group is attached. Examples of such monomers include 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate and, more preferably, 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. Other water-soluble nonionic monomers include N-vinyl pyrrolidone, vinyl acetate (hydrolyzed), 3-chloro-2-hydroxypropyl acrylate, 6-hydroxyhexyl acrylate, 5,6-dihydroxyhexyl methacrylate, and the like.

Addition polymers according to the invention which incorporate a non-ionic monomer include, for example, ethyl acrylate/hydroxyethyl methacrylate/methacrylic acid, methyl acrylate/hydroxyethyl acrylate/methacrylic acid, butyl acrylate/hydroxypropyl methacrylate/methacrylic acid, ethyl acrylate/N-vinylpyrrolidone/methacrylic acid, butadiene/hydroxyethyl methacrylate/ methacrylic acid and methyl acrylate/acrylamide/maleic acid.

Preferred polymers according to the invention containing nonionic monomers include: ethyl acrylate/hydroxyethyl methacrylate/methacrylic acid, ethyl acrylate/hydroxyethyl acrylate/methacrylic acid, ethyl acrylate/hydroxyethyl acrylate/acrylic acid, ethyl acrylate/hydroxyethyl methacrylate/acrylic acid and ethyl acrylate/acrylamide/methacrylic acid.

In order to reduce the tendency to develop stickiness at high relative humidity, it may be desirable to include a small amount of a water-insoluble hard monomer in the addition polymer according to the invention. Water-insoluble hard monomers of the invention which include polymerizable ethylenically unsaturated monomers include: benzyl acrylate or methacrylate, vinyl chloride, chlorostyrene, vinyl acetate and α-methylstyrene. A preferred group of water-insoluble hard monomers includes: acrylonitrile, methacrylonitrile and styrene.

Improved results have been obtained with, and it is consequently preferred to use as hard monomer, a C-1 to C4-alkyl methacrylate. Typical examples of such monomers include ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate and sec-butyl methacrylate. A particularly preferred hard monomer is methyl methacrylate.

Examples of preferred polymers according to the invention which contain such hard monomers include: butyl acrylate/methyl methacrylate/methacrylic acid, ethyl acrylate/methyl methacrylate/methacrylic acid and methyl acrylate/methyl methacrylate/acrylic acid.

When sufficient water solubility is to be given to the polymer, the degree of neutralization of the anionic groups with a cation such as ammonia or a metal cation from group IA, used as a base or a basic salt, will vary depending on the proportion of anionic monomer used in the polymer. The metal cation can be sodium, potassium, lithium or the like. The base can be a hydroxide and the basic salt a bicarbonate, a carbonate or the like. Polymers with a high proportion of anionic monomer may only need a low degree of neutralization and conversely polymers with a small proportion of anionic monomer may need a high degree of neutralisation, and it is possible to have 0 to 100% neutralization of the anionic monomer. Furthermore, it is not necessary to over-neutralize the anionic monomer.

It may be possible to use other metal cations in the neutralization compound. The metal cations from group II have been found to be somewhat less effective than the metal cations from group IA in providing solubility in aqueous solutions and solutions of synthetic detergents for the polymer.

The proportions of monomers used in the polymer sheet according to the invention should be suitable to provide balanced properties for rapid water solubility and satisfactory mechanical properties, such as flexible tearing and dimensional stability at low and high relative humidity and low temperature.

It is usually used at least approx. 40% by weight of the soft monomer to give sufficient flexibility at low temperature to the polymer sheet. It may be possible to use less than 40% of soft monomer. In this case, it is often necessary to use plasticizers to get the necessary flexibility in the sheet. Usually, it can be used up to approx. 8 5% by weight of soft monomer. It is preferably used from approx. 40 to 85% by weight of soft monomer, and it is most preferred to use approx. 60 to 80% by weight of soft monomer.

Usually, in order to provide the minimally desirable water solubility for the polymer in the washing liquid for washing clothes containing synthetic detergents or the like, at least approx. 15% by weight and up to approx. 100% by weight of water-soluble anionic monomer. As the amount of anionic monomer used is increased, it has been found that the neutralized polymer can become increasingly brittle, especially at low relative humidity or low temperature. In order to provide improved flexible tearing properties at low humidity for the sheet, it is preferred to use from approx. 15 to 50% and more preferably from approx. 15 to 40% of the water-soluble anionic monomer. To achieve the best results, the ionizable groups in the anionic monomer after polymerization should be neutralized up to 100% to achieve solubility. Polymers with a low proportion of anionic monomer usually need a high degree of neutralization, and conversely polymers with a high proportion of anionic monomer usually need a low degree of neutralization.

When the soft monomer used contains higher alkyl groups, such as butyl groups, larger amounts, within the range indicated above, of anionic monomer are usually used to provide satisfactory dissolution of the polymer. Under such circumstances, it can be used from approx. 40 to 60% of anionic monomer. If desired, part of the anionic monomer can be replaced by a water-soluble non-ionic monomer in the invention.

The water-soluble non-ionic monomer of the invention can increase the water solubility of the addition polymer of the invention by adding ionizable functionalities thereto. It is usually arbitrary to use the water-soluble non-ionic monomer, especially when the polymer sheet is not exposed to low relative humidity and/or low temperature.

Usually, it is the particular amount of non-ionic monomer

which is used, not critical. It is usually used from approx. 0

to 40% by weight, and amounts from approx. 0 to 15% by weight. It is best to use significant amounts of nonionic monomer within the wide range when using soft acrylates having longer alkyl chains, such as butyl groups or 2-ethylhexyl groups.

The water-insoluble hard monomer of the invention is used, as desired, within the general broad limits. The hard monomer has been found to be useful in reducing the stickiness of the resulting polymer at high relative humidity. No significant amounts of hard monomer are used, since such tend to reduce flexibility at low temperature for the polymer in sheet form. Consequently, from 0 to 20% by weight of hard monomer is used.

Preferred addition polymers capable of forming self-supporting films are prepared from the following monomers having the indicated properties:

Among the factors that affect the solubility and mechanical properties of the film is the molecular weight. Generally, as the molecular weight is reduced, the mechanical properties of the polymer tend to become less desirable. It has also previously been thought that when the molecular weight of the polymer increases and other factors, such as anionic monomer quantity and degree of neutralization etc., are kept constant, the degree of dissolution is reduced. However, it has now been found that polymers with 15% by weight or more of anionic monomer are soluble even at very high molecular weight, even if they are neutralized up to 100% or less. At over 15% of anionic monomer, the polymer dissolves to a reasonable extent even at cold wash temperatures of approx. 15.5°C. It is also now possible, if desired, to improve mechanical properties by using a polymer with a higher molecular weight without sacrificing solubility.

At high relative humidities (RH), usually above approx. 75%

RH, which is sometimes encountered during storage or use, it has been found that the polymer film of the invention can become more tacky. Polymer sheets may be prone to stick together, especially when stored in a roll or other type of dispenser form at high relative humidity. It may therefore be desirable, in order to reduce and/or eliminate this tendency, to apply a barrier coating to the outer surface of the polymer sheet. The barrier layer tends to insulate the sheet with respect to the effects of moisture penetration under humid storage conditions.

The barrier coating used should dissolve easily or break up when the sheet is introduced into water. In one aspect, suitable barrier coatings typically contain a film-forming hard component, a plasticizer component, and an emulsifier. Typical film-forming barrier coatings include paraffin wax and glyceryl monostearate. Typical emollient components include lanolin and petrolatum. Typical emulsifiers include stearic acid and the like. The materials referred to above can perform several functions. Glyceryl monostearate, for example, can act both as an emulsifier and as a film-forming material, while lanolin can act both as an emulsifier and as a plasticizer. In another aspect, suitable barrier coatings typically contain a film-forming component, a softening component, and a component to reduce cross-linking. A typical film-forming component is polyvinyl alcohol. Typical softening components include ethoxylated acrylate nonionic surfactants. Typical components to reduce cross-linking include ethoxylated phosphate ester anionic surfactants.

Typical barrier coatings, methods of making them and methods of applying them to a surface are disclosed in US Patent No. 3,322,674, issued May 30, 1967, US Patent No. 4,390,436, issued June 28, 1983 and US Patent No. 3,257,348, issued June 21, 1966. The disclosures in these patents are expressly incorporated herein by reference to the components, manufacture and use of the barrier coating.

It should be understood that one does not need to apply the barrier coating to the inner surface of the polymer sheet, which comes into contact with the laundry additives, such as a chlorine bleach. The film-forming polymer according to the invention resists the oxidizing effects of reactive laundry additives and does not require any internal barrier coating to protect either itself or the additive from deterioration.

To assist in providing sufficient flexibility for the polymer sheet at low temperature and/or low humidity, to prevent the polymer from drying out and becoming brittle, it may be desirable to use a plasticizer in the polymer preparation. Softeners are used which are resistant to oxidizing and other reactive effects of the additives for laundry, especially chlorine bleaches. A suitable plasticizer is glyceryl triacetate.

Such a plasticizer can be used in conventional amounts, usually approx. 5 to 40% by weight. Alternatively, to reduce brittleness, it may be desirable to use, in the polymer, small amounts of monomers that have a relatively low glass transition temperature. Such monomers as butyl acrylate, 2-ethylhexyl acrylate or hydroxyethyl acrylate can be used for this purpose.

The polymer film may optionally contain fillers to improve the physical properties, improve dissolution, reduce stickiness, increase modulus etc. Examples are talc, calcium carbonate, polymeric polystyrene or fibres.

It has been found that the optional inclusion of a small amount of a solubilizer or surfactant can sometimes assist in achieving dissolution of the sheet in use. Suitable surfactants can be added to the polymer sheet to aid dissolution during the wash cycle, and they can conventionally include one that is stable to bleaches and other reactive laundry additives.

The active laundry additive used in the laundry product according to the invention can be selected from a wide range of typical washing machine additives, including enzymes, bleaches, fabric softeners, builders, fabric conditioners, water softeners, wrinkle release agents additives and additives that give a special feel or grip to the laundry and the synthetic detergents. A particularly useful active component is a bleaching material which may be in particulate or wafer form.

Sufficient amounts of such laundry additives are used to provide an effective level of release to the wash liquor. It is usually found necessary to deliver from approx. 2 to 20 grams of additive, especially bleaching compound, to a typical washing liquid, depending on, for example, the amount of available bleaching species in the bleaching material. The actual percentage content of additive in the final sheet will depend on many factors, including the size and thickness of the sheet. For typical sheets, the ratio of chlorine bleach to polymer should be from approx. 10:1 to 1:2.

The bleaching preparation according to the invention is a dry bleaching agent of the chlorine type. The chlorine bleach may include alkali metal and alkaline earth metal hypochlorites, hypochlorite adducts, dimethyldihalogenhydantoin, chloramines, chlorimines, chloramides and chlorimides. Specific examples of such compounds include calcium hypochlorite, chlorinated trisodium phosphate dodecahydrate, chloramine T, and sodium dichloroisocyanurate. The preferred bleaching agents used are the chlorinated isocyanurates.

Other suitable bleaching agents include the inorganic peroxy bleaches and the organic peroxy bleaches. Typical inorganic peroxy bleaches are the alkali metal salts of perborates, persilicates, percarbonates and perphosphates. Suitable organic peroxy bleaches include urea peroxides or an organic peroxy acid or anhydride. Suitable aromatic peroxy acids and/or salts thereof include monoperoxyphthalic acid and diperoxyterephthalic acid•

The most preferred dry bleaches are the sodium and potassium dichloroisocyanurates or dichloroisocyanurate dihydrates, sodium perborate monohydrate, sodium perborate tetrahydrate, sodium percarbonate and mixtures thereof.

The addition polymer according to the invention is produced by comonomer-free radical polymerization, such as emulsion polymerization, solution polymerization and photo-polymerization.

Conventional emulsion polymerization techniques are well known and are described in US Patent Nos. 2,754,280 and 2,795,564. The comonomers can be emulsified, if necessary, with an anionic or nonionic dispersant, of which approx. 0.5 to 10%, based on the weight of the total monomers. A polymerization initiator of the free radical type, such as ammonium or potassium persulfate, can be used alone or in conjunction with an accelerator, such as potassium metabisulfite or sodium thiosulfate. The initiator and accelerator, usually referred to as the catalyst system, can be used in proportions from approx. 0.1 to 2%, each based on the weight of monomers to be polymerized. The polymerization temperature maintained during the reaction can be from room temperature to approx. 90°C or higher.

Examples of dispersants, surfactants and emulsifiers which are suitable for the polymerization process according to the invention include alkali metal and ammonium salts of alkyl, aryl, alkaryl and aralkyl sulphonates, -sulphate-ter and -polyether sulphates, and the corresponding phosphates and phosphonates and ethoxylated fatty acids, esters, alcohols, amines, amides and alkylphenols.

In order to regulate the molecular weight of emulsion polymers, it is preferred to use a chain transfer agent, such as a mercaptan, polymer captan or polyhalogen compound, in the polymerization mixture. Esters of mercaptoalkanoic acids are particularly preferred as chain transfer agents, and especially butylated mercaptopropionic acid (BMPA). The chain transfer agents are used in amounts that are typically from approx. 0.2 i.e. il 2% by weight.

Conventional solution polymerization techniques are well known. Monomers and initiators are brought together in a solvent-containing reactor. The solvent can be, for example, methanol for a relatively low reaction temperature, and methyl isobutyl ketone or glycol ether for a high reaction temperature. The temperature can be kept up to the boiling point of the chosen solvent. A typical polymerization initiator can be of the nitrile type, and it can be used in amounts of from approx. 0.1 to 5%, based on the weight of monomers to be polymerized.

Conventional photo-chemical polymerization techniques have also become well known. Monomers and photoinitiators are brought together, usually together with little or no solvent. The photo-initiator is a chemical compound that absorbs electromagnetic energy, usually ultraviolet or visible light, and produces one or more free radicals capable of initiating polymerization. The monomer solution, with added photo-initiator, can be converted directly into polymer film by drawing the solution to the desired thickness and then passing it under a source of ultraviolet light to initiate polymerisation. Typical photo-initiators can be benzophenone or derivatives, with or without added amine synergists, or acetophenone derivatives,

and it can be used from approx. 0.01 to 5% by weight, based on the monomers to be polymerized. A typical source of ultraviolet light is a medium pressure mercury vapor lamp with a power of 300 watts per 2.54 cm.

Example of polymer preparation The addition polymers according to the invention can be prepared as follows: A reactor is partially filled with deionized water and heated under nitrogen feeding to a temperature from approx. 85-95°C.

An aqueous solution of the initiator and, optionally, emulsifiers are then introduced. The reactor is then reheated to the reaction temperature, as required, and the addition of the comonomers is initiated. The comonomer feed includes all the comonomers of the invention and the chain transfer agent. The comonomer feed is preferably a slow feed over a period of 1 to 2 hours. During this time, the desired reactor temperature is maintained.

After all the monomers have been introduced into the reactor, the polymerization mixture is kept for approx. 45 minutes at the reaction temperature to ensure completion. The reaction mixture is then cooled and the latex is filtered off. A neutralized polymer composition is prepared by adding thereto a sodium hydroxide solution or the like to neutralize the polymer to up to 100% of theoretical.

If desired, the addition polymers of the invention can also be produced by suitable solution polymerization techniques. Such techniques may include a slow two-hour addition of co-monomers containing initiator to a Cellosolve (reaction solvent) containing reactor at reaction temperatures of about 115°C. After the monomer feed is complete, additional initiator is added to complete the polymerization.

Neutralized polymer films are prepared from neutralized solutions of the high solids polymer by casting or extrusion techniques. A polymer film according to the invention can, for example, be produced by drawing down a neutralized polymer with a high non-volatile (N.V.) content (25% N.V.) onto a polyethylene film with a Gardner knife or the like, and then drying the polymer film for 1 hour at 95°C. The dried polymer film is peeled off the polyethylene backing and then used as a polymer sheet to retain a laundry additive according to the invention.

The solid polymer can, if desired, be recovered from a latex or a solution using a film-drying evaporator or the like. The solid polymer can be treated with base in a Banbury type mixer, extruded, and then residual water can be removed by venting and the molten ionomer extruded as a sheet. A laundry additive is dispensed onto the sheet, another sheet is placed on top of the first to form a sandwich, or the first sheet is folded over the additive, and the resulting package is heat sealed.

If desired, the polymer according to the invention can also be produced by suitable photo-polymerization techniques. The selected monomers are brought together, in the desired proportions, with added solvent, if desired. The neutralizing base, for example sodium, lithium or potassium hydroxide, is added in the necessary amount to achieve the desired degree of neutralization for the anionic monomer. If necessary, water can be added to help dissolve monomer salts in the monomer solution. A surfactant, for example sodium lauryl sulfate, may be added if necessary to solubilize or emulsify any of the components of the monomer solution. Plasticizers, for example glyceryl triacetate, can be added if desired to improve the mechanical properties of the polymer. The photo-initiator is dissolved in the monomer solution. The comonomer solution is cast to the required wet-film thickness to achieve the desired dry-film thickness, and it is then passed under a source of ultraviolet light for a sufficient time to ensure complete polymerization. A laundry additive is dispensed onto the sheet, another sheet is placed on top of the first to form a sandwich, or the first sheet is folded over the additive, and the resulting package is heat-sealed.

It is important that the laundry additive forms a relatively thin, preferably monoparticulate layer, which is retained within the polymer sheets. If some pockets of additive remain on the laundry product, the pockets may cause the sheet material to break during handling. The product should therefore be formed so that additive pockets or cells are prevented from forming, and that the formation of a thin, monoparticulate layer of additive anchored within the product is promoted.

For this purpose, the laundry additive is distributed evenly on a polymer sheet, either as particles or as wafers. The polymer sheet can then be folded over itself or another sheet can be applied over the dispensed additive. Then, under relatively mild conditions of heat and pressure, the layers of sheet material containing dispensed additive are united with each other and with the dispensed particulate or wafer additive therein to form a uniform monolithic matrix. It is a key advantage of the present invention that the laundry product is a uniform matrix or a laminate which thoroughly anchors and retains the additive particles or wafers, and thus prevents the formation of pockets or cells of additive.

During closure, the polymer sheet softens and at least partially flows into the spaces or voids between the additive particles or wafers, thus anchoring it and keeping them from moving, uniting the polymer sheet and the particles or wafers into a single unit.

In a preferred embodiment, the closing conditions and the thickness of the sheet used are regulated to allow the film to flow substantially into the spaces between the dispersed particles or wafers. In another aspect of this invention, if desired, the closing conditions are adjusted so as to allow the film to completely fill the voids and thus encapsulate the particles or wafers. In another embodiment, the closing conditions are chosen so that the film is only allowed to become sticky and bind the particles or wafers in the unit so that little film flows into the spaces.

When laundry additives are used that are not water sensitive, such as certain fabric softeners and synthetic detergents, such additives may, if desired, be dispersed or mixed into the latex or solution at any stage before or after polymerization is complete , and the entire mixture of polymer and additive can be formed into a uniform sheet by extrusion, film casting or the like. In this embodiment, the additive can be embedded in the surface of, or even completely into, the sheet matrix.

To achieve the best results, the product is formed by

to unite an overfolded sheet or two sheets, which therein contain additive, at temperatures which are preferably from approx. 80-120°C. The pressure and temperature chosen will partly depend on the identity of the monomers used in the polymer film.

In general, a laundry product according to the invention is usually from approx. 32 to 516 cm o in area, preferably 64 to 129 cm , to provide sufficient storage space for the additive, although larger and smaller sheets may be used. The laundry product should be sufficiently thin to dissolve or disperse in warm water for approx. 20 minutes or less. However, the product should be sufficiently thick to provide a proper support.

For these and other purposes, it is preferred that the individual polymer sheets have a thickness of from approx. 0.00254 - 0.025.4 cm, preferably 0.00508 - 0.01524 cm. If desired, several layers of polymer films can be combined to form a single sheet.

The following examples are provided for illustrative purposes only, and should not be considered as limiting the scope.

In the following examples, parts and percentages are based on weight unless otherwise stated.

Example 1

A polymer was prepared from the following material: 94% ethyl acrylate/6% acrylic acid, neutralized to 150% of stoichiometric with 1.1 equivalents of sodium hydroxide and 0.4 equivalents of sodium bicarbonate.

Add 900 g of deionized water to a 2-liter flask. The water is heated under a nitrogen atmosphere to 85°C. Dissolve 1.5 g of ammonium persulphate in 50 g of deionized water and add to the flask. The solution is reheated to 85°C. A monomer feed is prepared from 470 g of ethyl acrylate, 30 g of acrylic acid and 5 g of butylated mercaptopropionic acid. This measure is added to the flask over a period of 90 minutes, with continuous stirring and maintenance of a temperature of 85°C. The latex is stirred for a further 60 minutes at 85°C, and then set aside to cool to room temperature. The latex has approx. 34% of non-volatile constituents. 18.32 g of sodium hydroxide is dissolved in 250 g of deionized water, and then slowly added to the latex. 13.99 g of sodium bicarbonate are added and stirred until this is dissolved. The latex now has approx. 29% of non-volatile constituents, and the polymer is 150% neutralized.

The neutralized latex was drawn onto a sheet of polyethylene film and air-dried. The dry film had a thickness of approx. 0.02032 cm. A bleach sheet was formed by cutting two pieces of film (7.62 cm x 10.16 cm). One piece of film was placed on a sheet of silicone release paper. 3 g of sodium dichloroisocyanurate dihydrate (ACL 56, from Monsanto) was showered evenly over the film. Another piece of film was placed over the ACL 56, and another sheet of silicone release paper was placed on top to form a sandwich. The sandwich was placed between the plates in a heated press, and then heated for 30 seconds on each side at 90°C and 1.05 kg/cm 2 , to form the bleach sheet by heat-sealing the polymer film layers around the granules of ACL 56. The silicone release paper was removed. The bleaching sheet was coated on both sides with a thin moisture-blocking coating of 4 parts stearic acid: 1 part

paraffin, and then lightly dusted with talc.

The bleach sheet was stored at 32.2°C and a relative humidity of 75%. After one week, the sheet had lost 11.4% of its available chlorine. The loss after 4 weeks was 28.3%.

Example 2

Polymer films were prepared as in Example 1, except that the polymers were neutralized to 110%, 130% and 150% respectively with lithium hydroxide. Bleaching sheets were produced from these films as in example 1, using 5 g of ACL 56 per sheet (7.62 cm x 10.16 cm). The sheets were stored at 32.2°C and 75% relative humidity. The sheet neutralized to 110% lost 14.4% of its available chlorine after 7 days, the 130% - sample lost 14.1% after 6 days (or about 16.4% at 7 days) and the 150% - sample lost 17, 4% after 7 days. The chlorine stability of the bleaching sheet clearly decreased with increasing pH and degree of neutralization.

Example 3

A series of polymers with the composition 84% ethyl acrylate/10% hydroxyethyl methacrylate/6% acrylic acid was prepared by the method from example 1. The amount of BMPA was varied to thus vary the molecular weight. All the polymers were neutralized to 120% with sodium hydroxide. The following results were recorded:

These results clearly show that polymer film properties improve as molecular weight increases. They also clearly show that, even with over-neutralization of the polymer, it is almost impossible to maintain polymer solubility with increasing molecular weight at low proportions of water-soluble anionic monomer.

Example 4

A polymer with the following composition was prepared:

40% ethyl acrylate/40% butyl acrylate/20% acrylic acid, neutralized to 95% of stoichiometric with sodium hydroxide. 750 g of methanol, 40 g of ethyl acrylate, 40 g of butyl acrylate and 20 g of acrylic acid are added to a 3-liter flask, equipped with a dropping funnel and cooler. It is started with heating under a nitrogen atmosphere to reflux. While heating, but before reflux, 0.2 g of 2,2'-azobis(isobutyronitrile) (Vazo 64, DuPont) dissolved in 50 g of methanol is added. Reflux is maintained for 15 minutes, then the dropwise addition of monomer feed consisting of 200 g of methanol, 160 g of ethyl acrylate, 160 g of butyl acrylate, 80 g of acrylic acid and 0.7 g of Vazo 64 is begun. The monomers should be added over a period of 90- 100 minutes. Reflux is maintained for a further 90 minutes, and then 0.5 g of Vazo 64 in 10 g of methanol is added. Stirring and reflux under nitrogen are continued for a total of 24 hours, 90 g of methanol are added and cooled to room temperature. The polymer solution now has approx. 31.2% non-volatile substances. The polymer is neutralized by the slow addition of 52.7 g of sodium hydroxide in 400 g of deionized I 2 O. The polymer solution now has approx. 25% non-volatile substances. The weight average molecular weight is 217,830.

A polymer film and a bleaching sheet are prepared as in example 1 with 2.5 g of ACL 56 per sheet (5.08 x 7.6 2 cm). No coating is applied. The film is strong and flexible, and is soluble in tap water (15.6°C). The bleaching sheet is stored at 32.2°C and 75% relative humidity. After one week it has lost 0.8% of its available chlorine and after 4 weeks it has lost only 3.3%.

It is clear that the use of larger proportions of anionic monomer has provided clear improvements over previous polymers:

higher molecular weight gives good film properties,

- the polymer is, surprisingly, very soluble even though it has a high molecular weight and is less than completely neutralized,

the bleach sheet is dramatically improved in terms of chlorine stability compared to previous polymers.

Example 5

A series of polymers were prepared, as outlined in the table below. Emulsion polymers were prepared following the techniques of Example 1, and solution polymers were prepared as in Example 4. All polymers were neutralized, as specified in the table below, by dissolving the base in sufficient deionized water to reduce the final polymer concentration to 20-25 wt. %, and adding the base solution to the polymer solution. Polymer films were prepared as in Example 1, with a thickness of 0.0127-0.0254 cm. Some of the bleaching sheets were prepared as in Example 1, with 5.0 g of ACL 56 granules per sheet (7.62 cm x 10.16,-\cm) . Other bleaching sheets were heat-sealed in the same way, but ACL 56 was used as six 0.95 gram portions per (7.62 cm x 10.16 cm) sheet, where each portion had been pressed in a tablet press into a wafer of 25 mm diameter and 1.2 mm thickness, and the wafers were evenly distributed over the sheet. None of the bleaching sheets had any moisture barrier coating.

These results clearly demonstrate the hitherto unrecognized benefits

in the formation of bleaching sheets from polymers having more than 15% of anionic monomers. These polymers are completely soluble, even at 15.5°C, regardless of molecular weight, although they may be less than 100% neutralized. Furthermore, by using such polymers, a significant reduction in the loss of chlorine during storage, especially at high temperature and humidity, has been achieved.

Example 6

A polymer was prepared with this composition: 60% butyl acrylate/40% acrylic acid, neutralized to 50% of the stoichiometric with sodium hydroxide.

To a 3-liter flask, equipped with a dropping funnel and condenser, add this initial monomer mixture: 60 g of butyl acrylate, 40

g acrylic acid, 575 g methanol and 0.12 g Vazo 64. It is heated to reflux under a nitrogen atmosphere. It is agitated at reflux for 15 minutes, and then, over a period of 90 minutes, this monomer feed is added: 240 g of butyl acrylate, 160 g of acrylic acid, 250 g of methanol and 0.50 g of Vazo 64. It is agitated at reflux run under nitrogen for an additional 90 minutes and then, over a final 30 minute period, add the final initiator feed: 100 g methanol and 0.20 g Vazo 64. Agitation at reflux is continued for 20 hours after the final allowance, and then cool to room temperature. The non-neutralized polymerization will then have approx. 35% solids. The weight average molecular weight is 145,800.

The polymer is neutralized to 50% of stoichiometric by slow addition of 1387.7 g of a 4.0% aqueous solution of sodium hydroxide. The partially neutralized polymer solution now has approx. 18% solids. A plasticizer is added by adding 50 g of glyceryl triacetate to the solution.

Polymer film and bleaching sheet were prepared as described in Example 1, using 5.0 g of granules of ACL 56 per sheet (7.62 cm x 10.16 cm). The film is flexible at room temperature,

and is completely soluble in tap water (15.5°C). The bleach sheets were stored at 32.2°C and R.H. of 75%. After 2 weeks there was a loss of 6.0% of available chlorine.

Additional bleach sheets were formed, using wafers of ACL 56 rather than granules. Each sheet (7.62 cm x 10.16 cm) had 6 wafers, each containing 0.93 g of ACL 56 and measuring 25 mm in diameter and 1.2 mm thick. The wafers are formed in a conventional rotary tablet press. Wafer-containing bleaching sheets are heat-sealed as in Example 1, with sealing for 5 seconds at 121.1°C and 2.81 kg/cm 2 . The bleach sheets were stored at 32.2°C and a R.H. of 75%. After 4 weeks, 3.4% of available chlorine had been lost, and after 8 weeks the loss was 7.0%.

Example 7

A polymer was prepared using the same composition and technique as in Example 6, except that it was formed with an overall batch size of 43.36 with 35% solids. The resulting non-neutralized polymer had a weight average molecular weight of approx. 350,000. It was neutralized to 50% of the stoichiometric with sodium hydroxide solution using the method of Example 6. 3.17 kg of glyceryl triacetate was added as a plasticizer. Film was cast and air-dried as in Example 1, to a dry film thickness of 0.027 cm. The film was completely soluble in tap water (15.5°C).

An anti-stick coating was applied to one side of the film to prevent stickiness that can develop at high temperature and humidity. The coating consisted of 75% partially hydrolyzed polyvinyl alcohol (Vinol 205, from Air Products), 10% nonionic polyoxyethylene arylates (Pycal 94 from I.CI.) and 15% anionic phosphate ester (Gafac LO 529, from G.A.F.). It was prepared as a 25% solution in water, rolled onto the film with a #16 wire-wound bar, and air-dried.

Wafer-containing bleach sheets containing 6 wafers in each bleach sheet (7.62 cm x 10.16 cm) were formed as in Example 6, except that each wafer contained 0.833 g of ACL 56, 0.151 g of sodium acid phosphate, 0.010 g of magnesium stearate. and 0.006 g of a fluorescent whitening agent (Tinopal CBS-X, from Ciba-Geigy). The sheets were formed so that the coating on the film was on the outside of the bleaching sheet.

Both the film and the bleaching sheet were completely soluble in tap water (15.5°C), and were very flexible even after 24 hours in a refrigerator at 4.4°C. Bleach sheets were stored at 32.2°C and R.H. of 75%. After 1 week, the loss of available chlorine was 0.8%, and

after 2 weeks the loss was only 3.0%.

Example 8

A polymer with the following composition was prepared:

60% butyl acrylate/40% acrylic acid, neutralized to 70% of stoichiometric with potassium hydroxide.

An initial monomer solution was prepared by mixing together 60 g of butyl acrylate, 40 g of acrylic acid, 20 g of methanol, 21.7 g of potassium hydroxide, 3.0 g of lauryl sulfate and 0.10 g of 2,2-dimethoxy-2-phenyl-acetophenone. (a photo-initiator, Irgacure 651 from Ciba-Geigy). To 50 g of this solution was added, as a thickener, 15 g of the non-neutralized polymer solution prepared in Example 7 (except that it was formed with 45% solids), and 1.4 g of additional potassium hydroxide . The monomer solution became quite viscous. The monomer solution was drawn with a Gardner knife on a glass plate to a film thickness of approx. 0.0101 cm, and then passed under a medium-pressure mercury vapor lamp with 300 watts per 2.54 cm with a speed of 13.7 meters per second. minute to produce a fully cured film. The resulting film had a thickness of 0.0101 cm and was very tough and flexible, and was completely soluble in tap water (15.5°C).

Claims (14)

1. Water-soluble sheet for dispensing additives for laundry, characterized by a self-supporting film of an addition polymer formed by: (a) from approx. 0 to 85% by weight of a water-insoluble soft monomer, (b) from about 15 to 100% by weight of a water soluble anionic monomer, (c) from approx. 0 to 25% by weight of a water-soluble non-ionic monomer and (d) from approx. 0 to 40% by weight of a water-insoluble hard monomer, where said addition polymer is up to approx. 100% neutralized with a group IV metal base or a salt of a group IA metal base. 2. Sheet according to claim 1, characterized in that the addition polymer is a terpolymer of from approx. 40 to 85% by weight of said water-insoluble soft monomer, from approx. 15 to 60% by weight of said water-soluble anionic monomer and from approx. 0 to 15% by weight of said water-soluble non-ionic monomer, and is neutralized up to approx. 100%. 3. Sheet according to claim 1 or 2, characterized in that the water-insoluble soft monomer is a C-1 - to C-16 alkyl acrylate or methacrylate. 4. Sheet according to claim 1, 2 or 3, characterized in that the anionic monomer is selected from methacrylic acid and acrylic acid. 5. Sheet according to claim 2, characterized in that the non-ionic monomer is selected from hydroxyalkyl acrylates or methacrylates which have an alkylene group with from 2 to 6 carbon atoms to which the hydroxy group is attached. 6. Laundry product, characterized in that a wafer additive for laundry is carried by the sheet according to claim 1. 7. Laundry product, characterized by a particulate additive for laundry that is carried by the sheet according to claim 1. 8. Laundry product, characterized by a unit formed by the sheet according to claim 1, which contains a uniformly dispersed particulate layer of laundry additive. 9. Laundry product, characterized by a unit formed by the sheet according to claim 1, which contains a uniformly dispersed wafer layer of additive for laundry. 10. Laundry product, characterized by a pair of opposite sheets formed by the film according to claim 1, which in between contain an additive for laundry. 11. Product according to claim 10, characterized in that the outer surface of each opposite sheet is provided with a moisture-resistant barrier coating. 12. Product according to claim 10, characterized in that the additive for laundry is a dry chlorine bleach. 13. Product according to claim 12, characterized in that the weight ratio between said bleaching agent and said polymer is from approx. 10:1 to 1:2. 14. Method for producing a laundry product, characterized by: (a) forming a unit including a dispersed layer of laundry additive and at least one sheet according to claim 1, and (b) close said entity.