A physically stable, concentrated isotropic liquid detergent composition comprises (a) from 10 to 70% of an anionic, nonionic, cationic, zwitterionic active detergent material or mixtures thereof, (b) from 0.0001 to 10% of protease; (c) from 2 to 40% of at least one carbohydrate selected from oligosaccharides, polysaccharides and derivatives thereof, wherein n=1-5, and (d) less than 3% of an antioxidant selected from the group consisting of alkalimetalsulphites, alkalimetalbisulphites, alkalimetabisulphites or alkalimetalthiosulphates.

The present invention relates to an enzymatic liquid detergent composition with good enzyme-stability. In particular, the present invention concerns a concentrated and physically stable isotropic liquid detergent composition with good protease stability suitable for cleaning textile articles.
In general, isotropic compositions are clear liquids wherein all the ingredients are dissolved. Concentrated isotropic liquid detergent compositions are very efficient in use and require less package and transport costs per wash. However, the high concentration of cleaning-effective ingredients is often problematic. One problem is to formulate a composition that is physically stable over a prolonged period of time as the highly concentrated surfactants tend to aggregate and separate out. This causes the composition to become hazy and physically unstable. Moreover, because other ingredients in the composition are also present in high concentrations, these ingredients may also separate out themselves or cause other ingredients to become insoluble.
Yet another problem is to ensure a sufficient storage-stability of the enzyme in concentrated liquid detergent compositions, particularly when protease is used. The prior art has already described various ways in which this problem can be overcome, e.g. by encapsulating the enzymes or by inclusion of enzyme-stabilising systems in such liquid detergent compositions. For example, glycerol/borax is a well-known enzyme stabilising system but, unfortunately, it is rather costly.
WO-A-98/40471 describes a method to improve the storage stability of dissolved laccase, an enzyme that catalyses the oxidation of phenol of which the reaction products can be used for dyeing hair or fabrics. The laccase is dissolved in water and sorbitol. There is no mention of the effect of carbohydrates on protease deactivation and the descriptions does not relate to isotropic liquid detergent compositions for the cleaning of fabrics.
U.S. Pat. No. 5,288,746 relates to liquid laundry detergent composition wherein glucose and glucose oxidase are used for the generation of hydrogen peroxide. To prevent premature hydrogen peroxide generation in the composition Cu2+ or Ag+ ions are incorporated in the composition. Therefore, glucose is not used as enzyme stabilising system but as a substrate for the enzyme.
EP-A-381 262 relates to the stabilisation of lipase in liquid detergent compositions with sorbitol and borax. Sorbitol is relatively expensive and there is a need for more economic alternatives.
U.S. Pat. No. 4,462,922 describes a liquid detergent wherein a mixture of glycerol, boron compound and an antioxidant containing sulphur is used to produce an enzyme-stabilising effect. For this mixture the antioxidant must be present above a certain level, as well as the boric acid or the alkali metal borate. The antioxidant should be present in the mixture in an amount of at least 5% by weight of the final enzymatic aqueous liquid detergent composition, and the boric acid or alkali metal borate in an amount of at least 2% by weight of the final enzymatic aqueous liquid detergent composition. The antioxidant is an alkalimetalsulphites, alkalimetalbisulphites, alkalimetabisulphites or alkalimetalthiosulphates.
However, this prior art composition is less desirable because sulphite salts tend to produce an unpleasant odour. Furthermore, applicants have found that it is problematic to incorporate the enzyme stabilising system of U.S. Pat. No. 4,462,922 in a concentrated isotropic liquid detergent because this leads to a hazy liquid which is no longer isotropic.
Surprisingly, we have now found that one or more of these problems can be overcome by the present invention while maintaining good protease stability.
Accordingly, the present invention provides a physically stable concentrated isotropic liquid detergent composition comprising
(a) from 10 to 70% of surfactant selected from anionic, nonionic, cationic, zwitterionic active detergent material or mixtures thereof,
(b) from 0.001 to 10% of protease;
(c) from 2 to 40% of at least one carbohydrate selected from oligosaccharides, polysaccharides and derivatives thereof; and
(d) less than 3% of an antioxidant selected from the group consisting of alkalimetalsulphites, alkalimetalbisulphites, alkalimetabisulphites or alkalimetalthiosulphates.
Furthermore, the present invention encompasses a method for the stabilisation of protease in a physically stable concentrated isotropic liquid detergent composition comprising the steps of
(I) formulating an said composition comprising
(a) from 10 to 70% of an anionic, nonionic, cationic, zwitterionic active detergent material or mixtures thereof,
(b) from 0.0001% to 10% of protease; and
(c) less than 3% of an antioxidant selected from the group consisting of alkalimetalsulphites, alkalimetalbisulphites, alkalimetabisulphites or alkalimetalthiosulphates, and
(II) adding 2 to 40% of at least one carbohydrate selected from oligosaccharides, polysaccharides and derivatives thereof, to the composition prepared in step (1).
One of the advantages of the present invention is that it provides a stable isotropic detergent composition that is simple to formulate and offers a significant cost advantage compared to glycerol/borax system.
A further advantage of the inventive composition is that the carbohydrate can be incorporated up to at least 20 wt % without causing physical stability problems.
The inventive composition comprises less than 3 wt %, more preferably less than 2 wt %, most preferably less than 1 wt % of the antioxidant selected from the group consisting of alkalimetalsulphites, alkalimetalbisulphites, alkalimetabisulphites or alkalimetalthiosulphates.
Isotropic liquid detergent composition are defined for the present purpose as liquid detergent compositions wherein the surfactants do not form liquid crystalline phases, like multi-lamellar droplets of surfactant material. Isotropic liquids are generally not birefringent under static conditions but may be birefringent under flow.
For the purpose of this invention a composition is physically stable when less than 2% phase separation occurs after 2 week storage at 37xc2x0 C. With isotropic liquids this can be phase separation generally starts with the liquid becoming hazy.
Carbohydrate
The carbohydrate is selected from oligosaccharides and polysaccharides e.g. having up to 30 carbon atoms, and derivatives thereof. The term xe2x80x9coligomerxe2x80x9d is usually taken to encompass dimers, trimers and tetramers. Oligosaccharides and their derivatives are especially preferred carbohydrates for use in the present invention, disaccharides, trisaccharides and derivatives thereof, being especially preferred.
One preferred class of preferred carbohydrates comprises the group comprising trisaccharides with a free hemiacetal group. Typical examples of this category are: Cellotriose (xcex2-D-glucopyranosyl-(1xe2x86x924)-xcex2-D-glucopyranosyl-(1xe2x86x924)-D-glucopyranose. Even more preferred are the trisaccharides without a free hemiacetal group (the so-called non-reducing trisaccharides). Typical example of this category is raffinose (xcex2-D-Fructofuranosyl xcex1-D-galactopyranosyl-(1xe2x86x926)-xcex1-(-D-glucopyranoside).
The most preferred carbohydrate comprises the disaccharides of non-mammalian origin. This does not include milk sugar lactose. More specifically the disaccharides with a free hemiacetal group (the so-called reducing disaccharides. Typical examples of this category are: Cellobiose (xcex2-D-glucopyranosyl-(1xe2x86x924)-D-glucose) xcex2-maltose (xcex1-D-glucopyranosyl-(1xe2x86x924)-xcex2-D-glucopyranose).
The most preferred disaccharides are compounds without a free hemiacetal group (the so-called non-reducing disaccharides. Typical disaccharides of the last category, are: Sucrose (xcex2-D-Fructofuranosyl xcex1-D-glucopyranoside) Trehalose (xcex1-D-Glucupyranosyl xcex1-D-glucopyranoside).
The composition herein preferably comprises 5-30%, more preferably 8-25% of at least one carbohydrate.
Additional Enzyme Stabilising System
In most cases the inventive composition will not need an additional measure to stabilise the enzyme. However, if needed small amounts of additional stabilising systems can be added, for example, those comprising, boric acid, propylene glycol, short chain carboxylic acids, boronic acids, and mixtures thereof, designed to address different stabilisation problems depending on the type and physical form of the detergent composition.
Another stabilising approach is by use of borate species. See Severson, U.S. Pat. No. 4,537,706. Borate stabilisers, when used, are preferably present in an amount of more than 0.1 and less than 5%, preferably less than 3%, more preferably less than 2.5% by weight of boric acid. Other borate compounds may be used such as borax or orthoborate suitable for liquid detergent use. Substituted boric acids such as phenylboronic acid, butaneboronic acid, p-bromophenylboronic acid or the like can be used in place of boric acid and reduced levels of total boron in detergent compositions may be possible though the use of such substituted boron derivatives.
Enzymes
xe2x80x9cDetersive enzymexe2x80x9d, as used herein, means any enzyme having a cleaning, stain removing or otherwise beneficial effect in a laundry application. Enzymes are included in the present detergent compositions for a variety of purposes, including removal of protein-based, carbohydrate-based, or triglyceride-based stains, for the prevention of refugee dye transfer, and for fabric restoration. Suitable enzymes include proteases, amylases, lipases, cellulases, peroxidases, and mixtures thereof. The enzyme may be of any suitable origin, such as vegetable, animal, bacterial, fungal and yeast origin. Preferred selections are influenced by factors such as pH-activity and/or stability optima, thermostability, and stability to active detergents, builders and the like. In this respect bacterial or fungal enzymes are preferred, such as bacterial amylases and proteases, and fungal cellulases.
Enzymes are normally incorporated into detergent or detergent additive compositions at levels sufficient to provide a xe2x80x9ccleaning-effective amountxe2x80x9d. The term xe2x80x9ccleaning effective amountxe2x80x9d refers to any amount capable of producing a cleaning, stain removal, soil removal, whitening, deodorising, or freshness improving effect on substrates such as fabrics. In practical terms for current commercial preparations, typical amounts are up to about 5 mg by weight, more typically 0.01 mg to 3 mg, of active enzyme per gram of the detergent composition. Stated otherwise, the compositions herein will typically comprise from 0.0001% to 10%, preferably from 0.001% to 5%, more preferably 0.005%-1% by weight of a commercial enzyme preparation.
The protease enzymes utilised in the present invention are usually present in such commercial preparations at levels sufficient to provide from 0.005 to 0.1 Anson units (AU) of activity per gram of composition. Protease enzymes are usually present in such commercial preparations at levels sufficient to provide from 0.005 to 0.1 Anson units (AU) of activity per gram of composition.
Suitable examples of proteases are the subtilisins, which are obtained from particular strains of B. subtilis and B. licheniformis. One suitable protease is obtained from a strain of Bacillus, having maximum activity throughout the pH range of 8-12, developed and sold as ESPERASE(trademark) by Novo Industries A/S of Denmark, hereinafter xe2x80x9cNovoxe2x80x9d. The preparation of this enzyme and analogous enzymes is described in GB 1,243,784 to Novo. Other suitable proteases include ALCALASE(trademark) and SAVINASE(trademark) from Novo and MAXATASE(trademark) from International Bio-Synthetics, Inc., The Netherlands; as well as Protease A as disclosed in EP 130,756 A, and Protease B as disclosed in EP 303,761 A and EP 130,756 A. See also a high pH protease from Bacillus sp. NCIMB 40338 described in WO 9318140 A to Novo. Enzymatic detergents comprising protease, one or more other enzymes, and a reversible protease inhibitor are described in WO 9203529 A. Other preferred proteases include those of WO 9510591 A. When desired, a protease having decreased adsorption and increased hydrolysis is available as described in WO 9507791. A recombinant trypsin-like protease for detergents suitable herein is described in WO 9425583.
Useful proteases are also described in PCT publications: WO 95/30010, WO 95/30011, WO 95/29979.
Preferred proteolytic enzymes are also modified bacterial serine proteases, such as those described in EP-A-251446 (particularly pages 17, 24 and 98), and which is called herein xe2x80x9cProtease Bxe2x80x9d, and in EP-A- 199404, which refers to a modified bacterial serine proteolytic enzyme which is called xe2x80x9cProtease Axe2x80x9d herein, Protease A as disclosed in EP-A-130756.
Amylases suitable herein include, for example, alpha-amylases described in GB 1,296,839 to Novo; RAPIDASE(trademark), (International Bio-Synthetics, Inc.) and TERMAMYL(trademark), (Novo). FUNGAMYL(trademark) from Novo is especially useful.
See, for example, references disclosed in WO 9402597. Stability-enhanced amylases can be obtained from Novo or from Genencor International. One class of highly preferred amylases herein have the commonality of being derived using site-directed mutagenesis from one or more of the Baccillus amylases, especially the Bacillus cc-amylases, regardless of whether one, two or multiple amylase strains are the immediate precursors.
Oxidative stability-enhanced amylases vs. the above-identified reference amylase are preferred for use, especially in bleaching, more preferably oxygen bleaching, as distinct from chlorine bleaching, detergent compositions herein. Such preferred amylases include (a) an amylase according to WO 9402597, known as TERMAMYL(trademark),
Particularly preferred amylases herein include amylase variants having additional modification in the immediate parent as described in WO 9510603 A and are available from the assignee, Novo, as DURAMYL(trademark). Other particularly preferred oxidative stability enhanced amylase include those described in WO 9418314 to Genencor International and WO 9402597 to Novo or WO 9509909 A to Novo.
Cellulases usable herein include both bacterial and fungal types, preferably having a pH optimum between 5 and 9.5. U.S. Pat. No. 4,435,307 discloses suitable fungal cellulases from Humicola insolens or Humicola strain DSM1800 or a cellulase 212-producing fungus belonging to the genus Aeromonas, and cellulase extracted from the hepatopancreas of a marine mollusk, Dolabella Auricula Solander. Suitable cellulases are also disclosed in GB-A-2.075.028; GB-A-2.095.275 and DE-OS-2.247.832. CAREZYME(trademark) (Novo) is especially useful. See also WO 9117243.
Suitable lipase enzymes for detergent usage include those produced by micro-organisms of the Pseudomonas group, such as Pseudomonas stutzeri ATCC 19.154, as disclosed in GB 1,372,034. See also lipases in Japanese Patent Application 53,20487. This lipase is available from Amano Pharmaceutical Co. Ltd., Nagoya, Japan, under the trade name Lipase P xe2x80x9cAmano,xe2x80x9d or xe2x80x9cAmano-P.xe2x80x9d Other suitable commercial lipases include Amano-CES, lipases ex Chromobacter viscosum, e.g. Chromobacter viscosum var. lipolyticum NRRLB 3673 from Toyo Jozo Co., Tagata, Japan; Chromobacter viscosum lipases from U.S. Biochemical Corp., U.S.A. and Disoynth Co., The Netherlands, and lipases ex Pseudomonas gladioli. LIPOLASE(trademark) enzyme derived from Humicola lanyginosa and commercially available from Novo, see also EP 341,947, is a preferred lipase for use herein. Lipase and amylase variants stabilised against peroxidase enzymes are described in WO 9414951 A to Novo. See also WO 9205249. Cutinase enzymes suitable for use herein are described in WO 8809367 A to Genencor.
The preferred liquid laundry detergent compositions according to the present invention further comprise at least 0.001% by weight, of a protease enzyme. However, an effective amount of protease enzyme is sufficient for use in the liquid laundry detergent compositions described herein. The term xe2x80x9can effective amountxe2x80x9d refers to any amount capable of producing a cleaning, stain removal, soil removal, whitening, deodorising, or freshness improving effect on substrates such as fabrics. In practical terms for current commercial preparations, typical amounts are up to about 5 mg by weight, more typically 0.01 mg to 3 mg, of active enzyme per gram of the detergent composition. Stated otherwise, the compositions herein will typically comprise from 0.001% to 5%, preferably 0.01%-1% by weight of a commercial enzyme preparation.
Peroxidase enzymes may be used in combination with oxygen sources, e.g., percarbonate, perborate, hydrogen peroxide, etc., for xe2x80x9csolution bleachingxe2x80x9d or prevention of transfer of dyes or pigments removed from substrates during the wash to other substrates present in the wash solution. Known peroxidases include horseradish peroxidase, ligninase, and haloperoxidases such as chloro- or bromo-peroxidase.
Peroxidase-containing detergent compositions are disclosed in WO 89099813 A, Oct. 19, 1989 to Novo and WO 8909813 A to Novo.
A range of enzyme materials and means for their incorporation into synthetic detergent compositions is also disclosed in WO 9307263 A and WO 9307260 A to Genencor International, WO 8908694 A to Novo, and U.S. Pat. No. 3,553,139, Jan. 5, 1971 to McCarty et al.
Surfactant
The compositions herein comprise from 10 to 70% by weight of an anionic, nonionic, cationic, zwitterionic active detergent material or mixtures thereof. Preferably the compositions herein comprise 12 to 60% of surfactant, more preferably 15 to 40%.
Non-limiting examples of other surfactants useful herein typically at levels from about 10% to about 70%, by weight, include the conventional C11-C18 alkylbenzene sulphonates (xe2x80x9cLASxe2x80x9d), the C10-C18 secondary (2,3) alkyl sulphates of the formula CH3(CH2)x(CHOS03-M+)CH3 and CH3(CH2)y(CHOS03-M+)CH2CH3 where x and (y+1) are integers of at least about 7, preferably at least about 9, and M is a water-solubilising cation, especially sodium, unsaturated sulphates such as oleyl sulphate, C10-C18 alkyl alkoxy carboxylates (especially the EO 1-7 ethoxycarboxylates), the C10-C18 glycerol ethers, the C10-C18alkyl polyglycosides and their corresponding sulphated polyglycosides, and C12-C18 alpha-sulphonated fatty acid esters. If desired, the conventional nonionic and amphoteric surfactants such as the C12-C18 alkyl ethoxylates (xe2x80x9cAExe2x80x9d) including the so-called narrow peaked alkyl ethoxylates and C6-C12 alkyl phenol alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), C12-C18 betaines and sulphobetaines (xe2x80x9csultainesxe2x80x9d), C10-C18 amine oxides, and the like, can also be included in the overall compositions. The C10-C18 N-alkyl polyhydroxy fatty acid amides can also be used. Typical examples include the C12-C18 N-methylglucamides. See WO 9,206,154. Other sugar-derived surfactants include the N-alkoxy polyhydroxy fatty acid amides, such as C10-C18 N-(3 -methoxypropyl) glucamide. C10-C20 conventional soaps may also be used. If high sudsing is desired, the branched-chain C10-C16 soaps may be used.
Mixtures of anionic and nonionic surfactants are especially useful. Other conventional useful surfactants are listed in standard texts.
Other anionic surfactants useful for detersive purposes can also be included in the compositions hereof. These can include salts (including, for example, sodium potassium, ammonium, and substituted ammonium salts such a mono-, di- and triethanolamine salts) of soap, C9-C20 linear alkylbenzenesulphonates, C8-C22 primary or secondary alkanesulphonates, C8-C24 olefinsulphonates, sulphonated polycarboxylic acids, alkyl glycerol sulphonates, fatty acyl glycerol sulphonates, fatty oleyl glycerol sulphates, alkyl phenol ethylene oxide ether sulphates, paraffin sulphonates, alkyl phosphates, isothionates such as the acyl isothionates, N-acyl taurates, fatty acid amides of methyl tauride, alkyl succinamates and sulphosuccinates, monoesters of sulphosuccinate (especially saturated and unsaturated C12-C18 monoesters) diesters of sulphosuccinate (especially saturated and unsaturated C6-C14 diesters), N-acyl sarcosinates, sulphates of alkylpolysaccharides such as the sulphates of alkylpolyglucoside, branched primary alkyl sulphates, alkyl polyethoxy carboxylates such as those of the formula RO(CH2CH20)kCH2COOxe2x80x94M+ wherein R is a C8-C22 alkyl, k is an integer from 0 to 10, and M is a soluble salt-forming cation, and fatty acids esterified with isethionic acid and neutralised with sodium hydroxide. Further examples are given in Surface Active Agents and Detergents (Vol. I and II by Schwartz, Perry and Berch).
The compositions of the present invention preferably comprise at least about 5%, preferably at least 10%, more preferably at least 12% and less than 70%, more preferably less than 60% by weight, of an anionic surfactant.
Alkyl sulphate surfactants, either primary or secondary, are a type of anionic surfactant of importance for use herein. Alkyl sulphates have the general formula ROS03M wherein R preferably is a C10-C24 hydrocarbyl, preferably an alkyl straight or branched chain or hydroxyalkyl having a C10-C20 alkyl component, more preferably a C12-C18 alkyl or hydroxyalkyl, and M is hydrogen or a water soluble cation, e.g., an alkali metal cation (e.g., sodium potassium, lithium), substituted or unsubstituted ammonium cations such as methyl-, dimethyl-, and trimethyl ammonium and quaternary ammonium cations, e.g., tetramethyl-ammonium and dimethyl piperdinium, and cations derived from alkanolamines such as ethanolamine, diethanolamine, triethanolamine, and mixtures thereof, and the like.
Typically, alkyl chains of C12-C16 are preferred for lower wash temperatures (e.g., below about 50xc2x0 C. and C16-C18 alkyl chains are preferred for higher wash temperatures (e.g., about 50xc2x0 C.).
Alkyl alkoxylated sulphate surfactants are another category of preferred anionic surfactant. These surfactants; are water soluble salts or acids typically of the formula RO(A)mSO3M wherein R is an unsubstituted C10-C24 alkyl or hydroxyalkyl group having a C10-C24 alkyl component, preferably a C12-C20 alkyl or hydroxyalkyl, more preferably C12-C18 alkyl or hydroxyalkyl, A is an ethoxy or propoxy unit, m is greater than zero, typically between about 0.5 and about 6, more preferably between about 0.5 and about 3, and M is hydrogen or a water soluble cation which can be, for example, a metal cation (e.g., sodium, potassium, lithium, calcium, magnesium, etc.), ammonium or substituted-ammonium cation. Alkyl ethoxylated sulphates as well as alkyl propoxylated sulphates are contemplated herein. Specific examples of substituted ammonium cations include methyl-, dimethyl-, trimethyl-ammonium and quaternary ammonium cations, such as tetramethyl- ammonium, dimethyl piperdinium and cations derived from alkanolamines, e.g., monoethanolamine, diethanolamine, and triethanolamine, and mixtures thereof. Exemplary surfactants are C12-C18 alkyl polyethoxylate (1.0) sulphate, C12-C18 alkyl polyethoxylate (2.25) sulphate, C12-C18 alkyl polyethoxylate (3.0) sulphate, and C12-C18 alkyl polyethoxylate (4.0) sulphate wherein M is conveniently selected from sodium and potassium.
The compositions of the present invention preferably comprise at least about 5%, preferably at least 10%, more preferably at least 12% and less than 70%, more preferably less than 60% by weight, of a nonionic surfactant.
Preferred nonionic surfactants such as C12-C18 alkyl ethoxylates (xe2x80x9cAExe2x80x9d) including the so-called narrow peaked alkyl ethoxylates and C6-C12 alkyl phenol alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), block alkylene oxide condensate of C6 to C12 alkyl phenols, alkylene oxide condensates of C8-C22 alkanols and ethylene oxide/propylene oxide block polymers (Pluronic(trademark)-BASF Corp.), as well as semi polar nonionics (e.g., amine oxides and phosphine oxides) can be used in the present compositions. An extensive disclosure of these types of surfactants is found in U.S. Pat. No. 3,929,678.
Alkylpolysaccharides such as disclosed in U.S. Pat. No. 4,565,647 are also preferred nonionic surfactants in the compositions of the invention.
Further preferred nonionic surfactants are the polyhydroxy fatty acid amides.
A particularly desirable surfactant of this type for use in the compositions herein is alkyl-N-methyl glucamide.
Other sugar-derived surfactants include the N-alkoxy polyhydroxy fatty acid amides, such as C10-C18 N-(3-methoxypropyl) glucamide. The N-propyl through N-hexyl C12-C18 glucamides can be used for low sudsing. C10-C20 conventional soaps may also be used. If high sudsing is desired, the branched-chain C10-C16 soaps may be used.
Another preferred anionic surfactant is a salt of fatty acids. Examples of fatty acids suitable for use of the present invention include pure or hardened fatty acids derived from palmitoleic, safflower, sunflower, soybean, oleic, linoleic, linolenic, ricinoleic, rapeseed oil or mixtures thereof. Mixtures of saturated and unsaturated fatty acids can also be used herein.
It will be recognised andat the fatty acid will be present in the liquid detergent composition primarily in the form of a soap. Suitable cations include, sodium, potassium, ammonium, monoethanol ammonium diethanol ammonium, triethanol ammonium, tetraalkyl ammonium, e.g., tetra methyl ammonium up to tetradecyl ammonium etc. cations.
The amount of fatty acid will vary depending on the particular characteristics desired in the final detergent composition. Preferably 0 to 30%, more preferably 1-20 most preferably 5-15% fatty acid is present in the inventive composition.
Optional Ingredients
The compositions herein can further comprise a variety of optional ingredients. However, preferably they are substantially free of amine. A wide variety of other ingredients useful in detergent compositions can be included in the compositions herein, including other active ingredients, carriers, hydrotropes, processing aids, dyes or pigments, solvents for liquid formulations, solid fillers for bar compositions, etc. If high sudsing is desired, suds boosters such as the C10-C16 alkanolamides can be incorporated into the compositions, typically at 1%-10% levels. The C10-C14 monoethanol and diethanol amides illustrate a typical class of such suds boosters. Use of such suds boosters with high sudsing; adjunct surfactants such as the amine oxides, betaines and sultaines noted above is also advantageous. If desired, soluble magnesium salts such as MgC12, MgSO4, and the like, can be added at levels of, typically,0.1%-2%, to provide additional suds and to enhance grease removal performance.
Various detersive ingredients employed in the present compositions optionally can be further stabilised by absorbing said ingredients onto a porous hydrophobic substrate, then coating said substrate with a hydrophobic coating. Preferably, the detersive ingredient is admixed with a surfactant before being absorbed into the porous substrate. In use, the detersive ingredient is released from the substrate into the aqueous washing liquor, where it performs its intended detersive function.
By this means, ingredients such as the aforementioned enzymes, bleaches, bleach activators, bleach catalysts, photo-activators, dyes, fluorescers, fabric conditioners and hydrolysable surfactants can be xe2x80x9cprotectedxe2x80x9d for use in detergents, including liquid laundry detergent compositions.
Liquid detergent compositions can contain water and other solvents as carriers.
Low molecular weight primary or secondary alcohols exemplified by methanol, ethanol, propanol, and isopropanol are suitable. Monohydric alcohols are preferred for solubilising surfactant. The compositions may contain from 5% to 90%, typically 10% to 50% of such carriers.
The clarity of the compositions according to the present invention does not preclude the composition being coloured, e.g. by addition of a dye, provided that it does not detract substantially from clarity. Moreover, an opacifier could be included to reduce clarity if required to appeal to the consumer. In that case the definition of clarity applied to the composition according to any aspect of the invention will apply to the base (equivalent) composition without the opacifier.
The detergent compositions herein will preferably be formulated such that, during use in aqueous cleaning operations, the wash water will have a pH of between about 6.0 and about 11, preferably between about 7.0 and 10.0. Laundry liquid products are typically at pH 7-9. Techniques for controlling pH at recommended usage levels include the use of buffers, alkalis, acids, etc., and are well known to those skilled in the art.
Builders
Detergent builders can optionally be included in the compositions herein to assist in controlling mineral hardness. Inorganic as well as organic builders can be used.
Builders are typically used in fabric laundering compositions to assist in the removal of particulate soils.
The level of builder can vary widely depending upon the end use of the composition and its desired physical form. When present, the compositions will typically comprise at least about 1% builder. Liquid formulations typically comprise from about 5% to about 50%, more typically about 5% to about 30%, by weight, of detergent builder. Lower or higher levels of builder, however, are not meant to be excluded.
Inorganic or P-containing detergent builders include, but are not limited to, the alkali metal, ammonium and alkanolammonium. salts of polyphosphates (exemplified by the tripolyphosphates, pyrophosphates, and glassy polymeric meta-phosphates), phosphonates, phytic acid, silicates, carbonates (including bicarbonates and sesquicarbonates), sulphates, and aluminosilicates. However, non-phosphate builders are required in some locales. Importantly, the compositions herein function surprisingly well even in the presence of the so-called xe2x80x9cweakxe2x80x9d builders (as compared with phosphates) such as citrate, or in the so-called xe2x80x9cunderbuiltxe2x80x9d situation that may occur with zeolite or layered silicate builders.
Examples of silicate builders are the alkali metal silicates, particularly those having a SiO2:Na2O ratio in the range 1.6:1 to 3.2:1 and layered silicates, such as the layered sodium silicates described in U.S. Pat. No. 4,664,839.
Examples of carbonate builders are the alkaline earth and alkali metal carbonates as disclosed in German Patent Application No. 2,321,001 published on Nov. 15, 1973.
Organic detergent builders suitable for the purposes of the present invention include, but are not restricted to, a wide variety of polycarboxylate compounds. As used herein, xe2x80x9cpolycarboxylatexe2x80x9d refers to compounds having a plurality of carboxylate groups, preferably at least 3 carboxylates. Polycarboxylate builder can generally be added to the composition in acid form, but can also be added in the form of a neutralised salt. When utilised in salt form, alkali metals, such as sodium, potassium, and lithium, or alkanolammonium salts are preferred.
Included among the polycarboxylate builders are a variety of categories of useful materials. One important category of polycarboxylate builders encompasses the ether polycarboxylates, including oxydisuccinate, as disclosed in Berg, U.S. Pat. No. 3,128,287 and Lamberti et al, U.S. Pat. No.3,635,830.
See also xe2x80x9cTMS/TDSxe2x80x9d builders of U.S. Pat. No. 4,663,071, issued to Bush et al, on May 5, 1987. Suitable ether polycarboxylates also include cyclic compounds, particularly alicyclic compounds, such as those described in U.S. Pat. Nos. 3,923,679; 3,835,163; 4,158,635; 4,120,874 and 4,102,903.
Other useful detergency builders include the ether hydroxypolycarboxylates, copolymers of maleic anhydride with ethylene or vinyl methyl ether, 1,3,5-trihydroxy benzene-2,4,6-trisulphonic acid, and carboxymethyloxysuccinic acid, the various alkali metal, ammonium and substituted ammonium salts of polyacetic acids such as ethylenediamine tetraacetic acid and nitrilotriacetic acid, as well as polycarboxylates such as mellitic acid, succinic acid, oxydisuccinic acid, polymaleic acid, benzene 1,3,5-tricarboxylic acid, carboxymethyloxysuccinic acid, and soluble salts thereof Citrate builders, e.g., citric acid and soluble salts thereof (particularly sodium salt), are polycarboxylate builders of particular importance for heavy duty liquid detergent formulations due to their availability from renewable resources and their biodegradability. Oxydisuccinates are also especially useful in such compositions and combinations.
Also suitable in the detergent compositions of the present invention are the 3,3-dicarboxy-4-oxa-1,6-hexanedioates and the related compounds disclosed in U.S. Pat. No. 4,566,984, Bush, issued Jan. 28, 1986. Useful succinic acid builders include the C5-C20 alkyl and alkenyl succinic acids and salts thereof. A particularly preferred compound of this type is dodecenylsuccinic acid. Specific examples of succinate builders include: laurylsuccinate, myristylsuccinate, palmitylsuccinate, 2-dodecenylsuccinate (preferred), 2-pentadecenylsuccinate, and the like. Lauryl succinates are the preferred builders of this group, and are described in European Patent Application 86200690.5/0,200,263, published Nov. 5, 1986.
Fatty acids, e.g., C12-C18 monocarboxylic acids, can also be incorporated into the compositions alone, or in combination with the aforesaid builders, especially citrate and/or the succinate builders, to provide additional builder activity. Such use of fatty acids will generally result in a diminution of sudsing, which should be taken into account by the formulator.
In situations where phosphorus-based builders can be used, and especially in the formulation of bars used for hand-laundering operations, the various alkali metal phosphates such as the well-known sodium tripolyphosphates, sodium pyrophosphate and sodium orthophosphate can be used. Phosphonate builders (see, for example, U.S. Pat. Nos. 3,159,581; 3,213,030; 3,422,021; 3,400,148 and 3,422,137) can also be used.
Chelating Agents
The detergent compositions herein may also optionally contain one or more iron and/or manganese chelating agents. Such chelating agents can be selected from the group consisting of amino carboxylates, amino phosphonates, polyfunctionally-substituted aromatic chelating agents and mixtures therein, all as hereinafter defined.
If utilised, these chelating agents will generally comprise from about 0.1% to about. 10% by weight of the detergent compositions herein. More preferably, if utilised, the chelating agents will comprise from about 0.1% to about 3.0% by weight of such compositions.
Clay Soil Removal/Anti-Redeposition Agents
The compositions of the present invention can also optionally contain water-soluble ethoxylated amines having clay soil removal and anti-redeposition properties.
Liquid detergent compositions typically contain about 0.01% to about 5%.
One preferred soil release and anti-redeposition agent is ethoxylated tetraethylenepentamine. Exemplary ethoxylated amines are further described in U.S. Pat. No. 4,597,898,
Another type of preferred anti-redeposition agent includes the carboxy methyl cellulose (CMC) materials. These materials are well known in the art.
Polymeric -Dispersing Agents
Polymeric dispersing agents can advantageously be utilised at levels from about 0.1% to about 7%, by weight, in the compositions herein. Suitable polymeric dispersing agents include polymeric polycarboxylates and polyethylene glycols, although others known in the art can also be used. It is believed, though it is not intended to be limited by theory, that polymeric dispersing agents enhance overall detergent builder performance, when used in combination with other builders (including lower molecular weight polycarboxylates) by crystal growth inhibition, particulate soil release peptisation, and anti-redeposition.
Unsaturated monomeric acids that can be polymerised to form suitable polymeric polycarboxylates include acrylic acid, maleic acid (or maleic anhydride), fumaric acid, itaconic acid, aconitic acid, mesaconic acid, citraconic acid and methylenemalonic acid.
Particularly suitable polymeric polycarboxylates can be derived from acrylic acid. Such acrylic acid-based polymers that are useful herein are the water-soluble salts of polymerised acrylic acid. The average molecular weight of such polymers in the acid form preferably ranges from about 2,000 to 10,000, more preferably from about 4,000 to 7,000 and most preferably from about 4,000 to 5,000. Water-soluble salts of such acrylic acid polymers can include, for example, the alkali metal, ammonium and substituted ammonium salts.
Acrylic/maleic-based copolymers may also be used as a preferred component of the dispersing/anti-redeposition agent. Such materials include the water-soluble salts of copolymers of acrylic acid and maleic acid. The average molecular weight of such copolymers in the acid form preferably ranges from about 2,000 to 100,000, more preferably from about 5,000 to 75,000, most preferably from about 7,000 to 65,000. Still other useful dispersing agents include the maleic/acrylic/vinyl alcohol terpolymers. Such materials are also disclosed in EP 193,360, including, for example, the 45/45/10 terpolymer of acrylic/maleic/vinyl alcohol.
Another polymeric material that can be included is polyethylene glycol (PEG). PEG can exhibit dispersing agent performance as well as act as a clay soil removal-anti-redeposition agent. Typical molecular weight ranges for these purposes range from about 500 to about 100,000, preferably from about 1,000 to about 50,000, more preferably from about 1,500 to about 10,000.
Polyaspartate and polyglutamate dispersing agents may also be used. Dispersing agents such as polyaspartate preferably have a molecular weight (avg.) of about 10,000.
Brightener
Any optical brighteners or other brightening or whitening agents known in the art can be incorporated at levels typically from about 0.05% to about 1.2%, by weight, into the detergent compositions herein. Commercial optical brighteners which may be useful in the present invention can be classified into subgroups, which include, but are not necessarily limited to, derivatives of stilbene, pyrazoline, coumarin, carboxylic acid, methinecyanines, dibenzothiphene-5,5-dioxide, azoles, 5- and 6-membered-ring heterocycles, and other miscellaneous agents. Examples of such brighteners are disclosed in xe2x80x9cThe Production and Application of Fluorescent Brightening Agentsxe2x80x9d, M. Zahradnik, Published by John Wiley and Sons, New York (1982).
Suds Suppressors
Compounds for reducing or suppressing the formation of suds can be incorporated into the compositions of the present invention. Suds suppression can be of particular importance in the so-called xe2x80x9chigh concentration cleaning processxe2x80x9d as described in U.S. Pat. Nos. 4,489,455 and 4,489,574 and in front-loading European-style washing machines.
A wide variety of materials may be used as suds suppressors, and suds suppressors are well known to those skilled in the art. See, for example, Kirk Othmer Encyclopedia of Chemical Technology, Third Edition, Volume 7, pages 430-447 (John Wiley and Sons, Inc., 1979). One category of suds suppressor of particular interest encompasses monocarboxylic fatty acid and soluble salts therein. See U.S. Pat. No. 2,954,347. The monocarboxylic fatty acids and salts thereof used as suds suppressor typically have hydrocarbyl chains of 10 to about 24 carbon atoms, preferably 12 to 18 carbon atoms. Suitable salts include the alkali metal salts such as sodium, potassium, and lithium salts, and ammonium and alkanolammonium salts.
The detergent compositions herein may also contain non-surfactant suds suppressors. These include, for example: high molecular weight hydrocarbons such as paraffin, fatty acid esters (e.g., fatty acid triglycerides), fatty acid esters of monovalent alcohols, aliphatic C18-C40 ketones (e.g., stearone), etc.
The preferred category of non-surfactant suds suppressors comprises silicone suds suppressors. This category includes the use of polyorganosiloxane oils, such as polydimethylsiloxane, dispersions or emulsions of polyorganosiloxane oils or resins, and combinations of polyorganosiloxane with silica particles wherein the polyorganosiloxane is chemisorbed or fused onto the silica. Silicone suds suppressors are well known in the art and are, for example, disclosed in U.S. Pat. No. 4,265,779.
For any detergent compositions to be used in automatic laundry washing machines, suds should not form to the extent that they overflow the washing machine.
Suds suppressors, when utilised, are preferably present in a xe2x80x9csuds suppressing amountxe2x80x9d.
By xe2x80x9csuds suppressing amountxe2x80x9d is meant that the formulator of the composition can select an amount of this suds controlling agent that will sufficiently control the suds to result in a low-sudsing laundry detergent for use in automatic laundry washing machines.
The compositions herein will generally comprise from 0.1% to about 5% of suds suppressor.
Fabric Softeners
Various through-the-wash fabric softeners, especially the impalpable smectite clays of U.S. Pat. No. 4,062,647 as well as other softener clays known in the art, can optionally be used typically at levels of from about 0.5% to about 10% by weight in the present compositions to provide fabric softener benefits concurrently with fabric cleaning. Clay softeners can be used in combination with amine and cationic softeners as disclosed, for example, in U.S. Pat. Nos. 4,375,416 and 4,291,071.
Dye Transfer Inhibiting Agents
The compositions of the present invention may also include one or more materials effective for inhibiting the transfer of dyes from one fabric to another during the cleaning process. Generally, such dye transfer inhibiting agents include polyvinyl pyrrolidone polymers, polyamine N-oxide polymers, copolymers of N-vinylpyrrolidone and N-vinylimidazole, manganese phthalocyanine, peroxidases, and mixtures thereof. If used, these agents typically comprise from about 0.01% to about 10% by weight of the composition, preferably from about 0.01% to about 5%, and more preferably from about 0.05% to about 2%.
Other than in the examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term xe2x80x9caboutxe2x80x9d. Similarly, all percentages are weight/weight percentages of the composition unless otherwise indicated. Where the term xe2x80x9ccomprisingxe2x80x9d is used in the specification or claims, it is not intended to exclude any terms, steps or features not specifically recited.
The invention is more fully illustrated by the following non-limiting examples showing some preferred embodiments of the invention.

Concentrated liquid detergent composition

Unilever Home and Personal Care USA, division of Conopco, Inc.


The formation of leachable mercury upon disposal or during TCLP testing of mercury vapor discharge lamps is substantially prevented by maintaining the amount of elemental iron at a level which is at least about 100 to about 1000 milligrams per kilogram of the total weight of lamp material.

This invention is directed to mercury vapor arc discharge lamps in which the arc discharge takes place in mercury vapor, including conventional phosphor fluorescent lamps and more particularly to avoidance of mercury pollution of landfills and ground eater upon disposal of such lamps and during testing for leaching of toxic materials from such lamps and to prevention of the formation of leachable mercury in disposal and testing procedures. The lamps provided herein are characterized by reduced solubilization and leaching of mercury when the lamp is pulverized for testing or upon disposal.
Low pressure mercury arc discharge lamps are standard lighting means which include electrodes sealed in a glass envelope, the interior of which may be coated with a phosphor. The lamp also contains a small amount of mercury and an inert gas at low pressure, of about 1 to 5 torr. The term lamp, as used herein, means the complete unit including the glass envelope and the end pieces and plugs for mounting in a lamp fixture, and wires which connect the internal components of the envelope with the end pieces.
During manufacture of fluorescent or low pressure mercury arc lamps an amount of elemental mercury (Hg.sup.0) is sealed in the lamp envelope. Most of the mercury adheres to the phosphor coating, a small amount being in the vapor phase.
During operation, alkali metal carbonates from the electrodes decompose and form free oxygen in the lamp. The oxygen may react with a portion of the mercury to form soluble mercury oxide (HgO). Soluble mercury oxide is leachable from land fills and other disposal facilities. Soluble mercury oxides or other oxidized forms of mercury formed in the course of the test are detrimental to the accuracy and reliability of the standard test for determination of the leachability of toxic materials from lamp waste. This test is generally referred to as the Toxicity Leaching Characteristic Procedure or TLCP test.
There is concern about the environmental impact of soluble mercury compounds which can leach into ground water sources, rivers, streams, and the like.

Control of leachable mercury in fluorescent lamps by iron addition


A microcapsule capable of thoroughly encapsulating environmentally-sensitive or volatile core materials and capable of releasing said core material on contact with water. A process for manufacture of water soluble microcapsules comprising the admixture of a water soluble cellulosic material, a water soluble glucopyranosidyl material, at least two surfactants and core material, subjecting said mixture to an abrupt pressure change and drying the pressure-treated mixture.

The present invention relates to water soluble microcapsule compositions, processes for their preparation and their uses in various applications including the food, nutriceutical and pharmaceutical industries.
Capsules have been developed to serve a variety of functions. One general purpose of encapsulation is to preserve or isolate the core material from its environment until an appropriate time or condition is present. In these situations, the core material is protected from the environment by the shell. Such protection is not always easily achieved since the core material may be able to penetrate or diffuse through the shell. On the other hand, use can be made of the xe2x80x9cleakyxe2x80x9d feature of some shells to control the release rate of the core material into the surrounding environment.
Encapsulation can protect compounds from environmental conditions such as temperature, pH, or chemically reactive surroundings such as oxidizing and reducing environments. Such oxidizing and reducing environments may consist of chemicals to which the capsule has been added. In other cases, it is desirable to encapsulate certain chemical compounds not only for protection of the core but also to protect or shield the external environment from reaction with the chemical compound forming the core. One common example of this use for encapsulation is the masking of the taste and/or odor of a chemical composition. In such a case, encapsulation may offer protection against detection of a bitter, toxic or otherwise undesirable taste or odor. Encapsulation of skin and respiratory irritants and toxins is one important way to protect the handlers of such materials from exposure.
A variety of micro-encapsulation methods and compositions are known in the art. These compositions are primarily used in food, agricultural and pharmaceutical formulations, for example, to flavor products, to mask the taste of bitter drugs, formulate prolonged dosage forms, separate incompatible materials, protect chemicals from moisture or oxidation, or modify the physical characteristics of the material for ease of handling and/or processing.
Many liquids, such as flavors and fragrance oils for example, contain a mixture of volatile alcohols and aromatics, which evaporate when exposed to even minimal heat. Indeed, many such substances often lose as much as 45% of their original weight during the encapsulation process due to volatilization. Such losses are wasteful and expensive. Additionally, resulting end-products of these methods often taste less poignant or smell less desirable than the original liquids.
Many of the techniques used to microencapsulate involve the polymerization or setting of a resin, such as a polyurea, to form the outer shell of the microsphere. Typical pharmaceutical encapsulation compositions include, e.g., gelatin, polyvinyl alcohol, ethylcellulose, cellulose acetatephthalate and styrene maleic anhydride. See Remington""s Pharmaceutical Sciences, Mack Publishing Co., Easton Pa. (1990). Other techniques use primarily fats, waxes or polymers to film form the outer shell.
The use of fats as a retention media for volatiles is disclosed in U.S. Pat. No. 3,949,094 of Johnson, et al. issued Apr. 6, 1976, wherein volatile flavorings, seasonings, colorants, flavor enhancers and the like are blended with lipoidal material under super atmospheric conditions for subsequent handling or conversion into particulates by a spray chilling process. While retention of the volatiles within fat under pressure reduces vaporization before processing, excessive losses are still experienced during the Johnson spray chilling encapsulation method.
Redding, U.S. Pat. No. 5,460,756 describes the entrapping of liquids within a stable lipid or wax shell using pressure pulse techniques.
Lim, et al., U.S. Pat. No. 4,389,419 describes the formation of an emulsion consisting of a continuous phase aqueous solution of an alkali metal alginate, and optionally, water-soluble alcohol-insoluble filler such as a polysaccharide, and a dispersed phase of an oleophilic substance. The emulsion thus produced is then formed into droplets, which are immersed into an alcoholic solution of multi-valent cations, to produce a water-insoluble shape-retaining alginate matrix filled with precipitated polysaccharide and enclosing plural oil droplets.
Another markedly different approach employed for encapsulating vitamin or mineral nutrients, such as thiamine, is described by Hall, et al., U.S. Pat. No. 4,182,778 issued Jan. 8, 1980. Hall, et al. describe encapsulation by fluidizing the nutrient in a gaseous stream and contacting the nutrient with finely atomized droplets of a coating solution.
Boyle et al, U.S. Pat. No. 5,925,381, describe the microencapsulation of oleophilic substances by forming an emulsion out of the oleophilic substance and a polymer, and then using heat setting and/or cross-linking of the polymer to encapsulate the oleophilic composition. This process is then repeated with a second polymer or third polymer, and with or without cross-linked via the same or different mechanism to further protect the oleophilic substance.
U.S. Pat. No. 4,353,962 discloses the in-flight encapsulation of materials for herbicidal, insecticidal and the like uses, for example, with film-forming polymers, in particular acrylic polymers from aqueous emulsion that may include a surfactant. The emulsion is spray dried onto the target in the form of a material encapsulated in a hardened x-linked acrylic encapsulating shell.
There is a need in the art for a microcapsule encapsulating active ingredients such as pharmaceuticals, herbicides, pesticides, flavors and fragrances, where the encapsulating shell is highly water soluble. Such a microcapsule would function to protect the encapsulated core material until placed into contact with an aqueous environment, when the active would be released instantly into the aqueous environment.
Water soluble microcapsules have been reported in the patent literature for many years for the preparation of storage stable flavors and fragrances using starch materials of one type or another as water soluble shell materials.
U.S. Pat. No. 3,455,838 discloses encapsulating lemon oil in a shell consisting of a dextrinized starch acid-ester of a substituted dicarboxylic acid. The encapsulate is prepared by mixing the lemon oil and an aqueous solution of the modified dextrin, passing it through a colloid mill, and spray drying the emulsion.
U.S. Pat. No. 3,499,962 discloses the encapsulation of water insoluble materials with a high amylose-containing starch material by mixing the insoluble material with an amylose solution at a temperature above 140 degrees F. and spray drying the mixture.
U.S. Pat. No. 5,370,881 discloses a micronized dispersion of flavor oil in a matrix of water soluble sucrose derivative such as isomalt. The matrix is formed in a flash flow process and the product is described as providing a rapid release of flavor.
U.S. Pat. No. 5,976,575 discloses encapsulated carotenoid oil prepared by emulsifying the oil with an aqueous solution of sugar, a starch encapsulating agent and an anti-oxidant, homogenizing the dispersion using a high pressure homogenizer and spray drying the resulting finely dispersed emulsion.
The use of other hydrophilic polymers such as cellulosic materials as the outer shell has also been described for encapsulated flavors as well as drug substances.
U.S. Pat. No. 3,664,963 discloses a lemon oil microcapsule encapsulated in a water soluble shell prepared from water soluble hydrophilic polymers including water soluble cellulosic compounds such as alkali cellulose, cellulose ethers and esters. The capsules are prepared from an oil in water emulsion of the lemon oil and polymer, which may include other ingredients including anti-oxidants and surfactants. The emulsion may be dispersed by a pressure homogenizer, and sprayed over polyethylene glycol to remove the water from the water soluble shell. The resulting capsules are coated with a layer of polyethylene glycol. The polyethylene glycol coated microcapsules are described as dissolving rapidly in cold water and which retain their fresh lemon flavor for an extended period of time in storage in the presence of air.
U.S. Pat. No. 4,540,602 discloses the encapsulation of scarcely soluble drugs with a water-soluble high molecular substance which can be one or a combination of materials such as cellulose derivatives such as hydroxypropyl methylcellulose, the sodium salt of carboxymethyl cellulose and other polymeric substances such as starches, gum arabic and the like. The drug and aqueous solution of high molecular weight substances are spray dried to form the microcapsules. The ""602 patent states the emulsion may contain a surface active agent, such as polysorbate 80, HCO-60, an addition polymer of hydrogenated castor oil with ethylene oxide but that such use can result in hemolysis. Later on in the disclosure, the ""602 patent discloses that small amounts of surfactants such as dioctyl sulfosuccinate, sucrose fatty acids and the like could be used because of their lack of hemolysis effect.
Other systems including the use of protein based materials and phospholipids have also been used as shell materials.
U.S. Pat. No. 5,601,760 discloses the microencapsulation of orange oil using a whey protein-based shell material which is dispersed in water with a starch or sugar, mixed with the orange oil, emulsified using a low and high speed homogenizer and spray dried.
U.S. Pat. No. 5,989,583 discloses liposomal composition described as quick dissolving powders prepared by homogenizing a solid fat and phospholipid and a surfactant, and spray drying the liposomal composition.
U.S. Pat. No. 5,317,004 discloses the microencapsulation of low melting herbicidal materials by admixing of a molten water insoluble core material with an aqueous solution of a water-soluble film forming polymer plus surfactant heated to a temperature that permits the core to remain molten and then spray drying the emulsion. Exemplary polymers include PVA, PVP and sodium carboxymethylcellulose. Exemplary surfactants include sodium dioctylsulfosuccinate.
While the methods of encapsulating water-insoluble materials with water soluble shell materials vary, there exists a need for an instant dissolvable microcapsule system that is storage stable for months under normal conditions, that may be prepared under conditions that minimize the oxidative and/or vapor loss impact on sensitive core materials such as flavors, fragrances, agricultural and drug substances.
The present invention relates to a water soluble microcapsule comprising a water insoluble core material and an encapsulating water soluble shell comprising a water soluble glucopyranosidyl material, at least two surfactants, and a water soluble cellulosic material.
The invention also relates to a process for the preparation of a water soluble microcapsule comprising subjecting an aqueous mixture of a water insoluble core material, a water soluble glucopyranosidyl material, a water soluble cellulosic material and an emulsifying composition to a pressure force to form an aqueous micro-emulsion, and removing the water from said micro-emulsion. This invention also relates to the water soluble microcapsule produced by the aforesaid process.
The primary advantages of the present invention include the preparation of a microcapsule that prevents environmental contact with an encapsulated water insoluble core material that is released from its encapsulating shell instantly on contact with an aqueous environment at ambient temperature. A further explanation of the unexpected advantages and benefits of the present invention are more fully described hereinbelow.
The following terms as defined hereinbelow are used throughout the present specification.
Encapsulation is applied to the formation from suitable materials of a shell that encloses a core material. The capsule that is formed may have a core material that is solid, liquid, gas, or a multi-phasic. Capsules having sizes ranging from approximately a micron to a few millimeters are generally referred to as microcapsules; although that term is not specifically defined in the literature. Capsules and/or microcapsules need not be uniformly spherical but may consist of irregularly-shaped objects such as those having a shell surrounding an irregular shaped solid crystalline core.
As used herein, the terms xe2x80x9cshellxe2x80x9d and xe2x80x9cwallxe2x80x9d are used interchangeably to denote the barrier surrounding the core material separating it from the environment. The shell or wall may likewise be complex having multiple walls of different composition. Thus, it is possible to have a first capsule having its own core and shell, which forms the core for a second capsule having a shell formed from the same or a different material.
The term xe2x80x9ccore materialxe2x80x9d is meant to define a material, preferably an organic material, which may comprise a single chemical compound or a mixture of chemical compounds and which is coated or encapsulated by the shell or wall material of the capsule. A capsule core may be a single solid crystal, a chemical compound, an emulsion, a liquid, a mixture of different solid materials or other suspensions, or it may be a combination of smaller capsules. A special embodiment of core materials include water insoluble compounds dissolved in a volatile organic medium, such as a low boiling point alcohol, or a low boiling point alkylene halide such as methylene chloride, or a non-volatile carrier oil, such as a low melting point fatty acid or fatty alcohols. Generally, any material that retains its shape and configuration in an aqueous medium, such as in the form of a suspended particle, colloid or emulsion, can be used as a core material.
The term xe2x80x9cwater insolublexe2x80x9d means that a material does not readily dissolve in water at room temperature. A material is considered water insoluble herein if a material is a mixture of chemical compounds, a minor fraction of which may be partially miscible in water.
The term xe2x80x9cambient temperaturexe2x80x9d means from about 5 degrees C. to about 35 degrees C. A most preferred ambient temperature is from about 15 degrees C. to about 25 degrees C.
The term xe2x80x9cinstantly releasedxe2x80x9d means that substantially all of the core material is released into its environment within less than about 5 seconds. A preferred instant release time is less than about 3 seconds, with the most preferred time less than about 2 seconds.
The term xe2x80x9cemulsifying compositionxe2x80x9d means a composition comprising one or more a non-toxic surfactants, preferably organic surfactants. The preferred emulsifying composition is capable of forming an aqueous emulsion in admixture with a water insoluble core material.
The term xe2x80x9cpressure forcexe2x80x9d means an abrupt pressure change, a pressure shock wave, shear force, and/or cavitation resulting from the rapid change in pressure experienced by a composition subjected to a high pressure pumping or ultrasonic apparatus. The preferred pressure force is believed to occur in either or both of the high pressure compression chamber and during subsequent depressurization in baffle or shear chambers present in commercially available apparatus.
The term xe2x80x9cspray dryingxe2x80x9d means the removal of water from an aqueous composition by forcing the composition through a narrow nozzle at high pressure into a volume of air or vacuum into which the water evaporates.
The microcapsule shell of the present invention is water soluble at ambient temperature conditions. In a preferred aspect, the microcapsule of the present invention dissolves instantly in water at ambient temperature thereby releasing its core material into the aqueous environment.
The advantages of the present invention to the food and beverage industry include the ability to provide flavors and fragrances that may be mixed in water without heating and that release their encapsulated flavors or fragrances immediately. The most preferred microcapsule dissolves instantly in cold water, that is at a temperature slightly above the freezing point, with only modest stirring. A further preferred water soluble microcapsule comprises an aromatic core material, preferably an organic composition including one or more compounds that have a low vapor pressure and are volatile at ambient temperature and pressure of about 1 atmosphere, the vapor pressure of which suppressed at ambient temperature.
The advantages of the present invention extend into many industries including pharmaceuticals, where active ingredients capable of mucosal absorption such as nitroglycerin may be formulated as microcapsules and compressed into tablets for oral administration, or used as powders for nasal or bronchial inhalation administration. Upon contact with the moist body temperature mucosa in the mouth, nasal passages or aveoli of the lung, the active ingredient would instantly be released for absorption into the patient""s bloodstream
Other industries also could benefit from the present invention. For example, herbicides and pesticides could be formulated such that they are applied to vegetation as dry granules that release on application of water, either by nature""s rain or the hand of man.
The present microcapsule comprises a core material, preferably an organic material, that is water insoluble or only slightly water soluble, and that is encapsulated or coated with a water soluble shell comprising a matrix of a water soluble glucopyranosidyl compound and an emulsifying composition.
xe2x80x9cGlucopyranosidyl materialxe2x80x9d means a composition including a compound containing a glucopyranosidyl ring structure, and mixtures thereof. A special embodiment of the glucopyranosidyl materials comprises the dissacharrides including the naturally occurring disaccharides and the enantiomers thereof; while another special embodiment comprises the enzymatically and/or chemically modified derivatives of the naturally occurring disaccharides, including hydrogenated, methylated, oxidized, acetylated, aminated and enzymatically rearranged derivatives thereof.
xe2x80x9cDisaccharidexe2x80x9d as used herein means an organic dimeric material considered as derived from the hydrolysis of polysaccharides that are branched or straight-chained, looped or coiled polymers of repeating monosacharride units formed from aldose or ketoses by condensation polymerization. An exemplary polysaccharide derived from hexoses has the general formula (C6H10O5)n. Disaccharides are glucopyranosidyl compounds made up of two monosacharride units. The trivial names of exemplary naturally derived disaccharides are maltose, sucrose, lactose, cellobiose, trehalose, gennobiose, isomaltose, melibiose, prieverose, and rutinose.
Exemplary glycopyranosidyl compounds that comprise the derivatives of the natural disaccharides, include maltobionic acid, octa-O-methyl-D-maltobionic acid, cellubiose octaacetate, lactobionic acid, isomaltulose(6-O-D-glucopyranosido-D-fructose), 1,2;4,5-di-O-isopropylidene-beta-D-fructopyranose, 1,2:5,6-di-O-isopropylidene-alpha-D-glucofurnaose, 2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranose, lactitol monohydrate; (+)-turanose, kojibiose, lactosamine, lactosediamine, laminarabiose, ngerose, sopharose, trehalosamine, alpha-D-glucopyranosyl-1,1-D-mannitol and alpha-D-glucopyranosyl-1,6-D-sorbital, and isomalt, an equimolar mixture of alpha-D-glucopyranosyl-1,1-D-mannitol and alpha-D-glucopyranosyl-1,6-D-sorbital, among others.
A particularly preferred subgroup of these derivatives comprises the compounds based on the 1-O- or 6-O-polyhydroxyalkylethers of glucopyranoside having a alkyl group containing about 5 to 6 carbon atoms ring and a total of about 12 to 14 carbon atoms, and wherein the side chain comprises about 4 to about 6 hydroxyl groups and optionally, about 1 to 2 carbonyl groups. The disaccharide derivatives may also be described as the result of the 1-O- or 6-O ether linkage of glucose to a conventional sugar alcohol, sugar carboxylic acid, or sugar dicarboxylic acid, examples of which include hexitols such as glucitol, galactitol, mannitol and gulitol; pentitols such as arabinitol, ribitol and xylitol; tetritols such as threitol and erythritol or glycerol, and derivatives of such sugar alcohols can be mono- or multiply-desoxygenated sugar alcohols such as L-rhamnitol, ribonic acid, gluconic acid and gulonic acid, and tartaric acid, galactaric acid and glucaric acid.
These sugar alcohols and sugar carboxylic acids can be present in the D- or L-form or as racemates, with the naturally occurring form or the form which corresponds to the basic, naturally occurring sugar being preferred.
The most preferred glucopyranosidyl materials are 1-polyhydroxyalkylethers of glucopyranoside that may be prepared by the selective Raney nickel hydrogenation of the corresponding reducing disaccharides, which comprise all the naturally occurring disaccharides excluding sucrose and trehalose, and include the enzymatically rearranged products of the non-reducing disaccharides such as sucrose and trehalose. A special embodiment of this invention utilizes as the glucopyranosidyl material, an equimolar mixture of alpha-D-glucopyranosyl-1,1-D-mannitol and alpha-D-glucopyranosyl-1,6-D-sorbital, sold under the tradename Isomalt.
A preferred microcapsule includes from about 2 to about 60 weight percent of said disaccharide or derivative thereof and about 1 to about 35 percent, or more preferably from about 10 to about 30 percent, of said core material. A special embodiment of the microcapsule includes about 50 percent of said disaccharide and about 20 percent of said core material. A most preferred microcapsule includes about 20 percent of said disaccharide and about 10 percent of said core material. The emulsifying composition comprises about 0.5 to about 3 percent of the dry microcapsule by weight, while a preferred microcapsule includes the emulsifying composition in about 1 percent by weight.
The emulsifying composition preferably includes at least two non-toxic surfactants. There are a great many surfactants, anionic, cationic, non-ionic or amphoteric in character, which may be employed, depending upon the hydrophobic substance to be employed. Among the well-known surfactants useful in the process of the present invention are the sorbitan esters of fatty acids having 10 to 22 carbon atoms; polyoxyethylene sorbitan esters of C10 to C22 fatty acids having up to 80% ethylene oxide; polyoxyethylene sorbitol esters of C10 to C22 fatty acids, polyoxyethylene derivatives of fatty phenols having 6 to 20 carbon atoms and up to 80% ethylene oxide; fatty amino and amido betaines having 10 to 22 carbon atoms; fatty alcohols of 5 to 16 carbon atoms, polyoxyethylene condensates of C10 to C22 fatty acids or fatty alcohols having up to 80% ethylene oxide; polyoxyethylene-polyoxypropylene block polymers; ionic surfactants such as the alkylaryl sulfonates of 6 to 20 carbons in the alkyl group; C10 to C22 fatty acid soaps; C10 to C22 fatty sulfates; C10 to C22 alkyl sulfonates; C10 to C22 fatty amine oxides; fatty imidazolines of C6 to C22 carbon atoms; fatty amido sulfobetaines having 10 to 22 carbon atoms; quaternary surfactants such as the fatty ammonium compounds having 10 to 22 carbon atoms; C10 to C22 fatty morpholine oxides, alkali metal salts of carboxylated ethoxylated C10 to C22 alcohols having up to 80% E.O., ethylene oxide condensates of C10 to C22 fatty acid monoesters of glycerins having up to 80% E.O. and the mono- or diethanol amides of C10 to C22 fatty acids, etc. As is well known in the field of surfactants, the counter ion in the case of anionic surfactants may be any of the alkali metals, ammonia, or substituted ammonias such as trimethylamine or triethanol amine. Usually ammonium, sodium and potassium are preferred. In the case of cationic surfactants, the counter ion is usually a halide, sulfate or methosulfate, the chlorides being the most common industrially available compounds. The foregoing compounds have been described with particular reference to fatty derivatives. It is the fatty moiety usually forming the lipophilic moiety. A common fatty group is an alkyl group of natural or synthetic origin. In most instances, the alkyl group may be replaced by the corresponding ethyleneically saturated group having one or more ethylene linkages such as commonly occur in nature. Common unsaturated groups are oleyl, linoleyl, decenyl, hexadecenyl, dodecenyl, etc. In appropriate cases, as known in the art, the alkyl group may be cyclic, i.e., cycloalkyls, or may be straight or branched chain.
Among the surfactants found particularly useful in accordance with the present invention are nonylphenol-polyoxyethylene condensates, the sorbitan and sorbital mono esters C12 to C18; fatty acids, and their ethylene oxide condensates.
Other representative primary surfactants are: sorbitol monolaurate-ethylene oxide condensates; sorbitol monomyristate-ethylene oxide condensates; sorbitol monostearate-ethylene oxide condensates; dodecylphenol-ethylene oxide condensates; myristylphenol-ethylene oxide condensates; octylphenyl-ethylene oxide condensates; stearylphenol-ethylene oxide condensates; lauryl alcohol-ethylene oxide condensates; stearyl alcohol-ethylene oxide condensates; secondary alcohol-ethylene oxide condensates such as commercial C14 to C15 secondary alcohols condensed with ethylene oxide (commercially available as xe2x80x9cTergitolxe2x80x9d); decyl amino betaine; coco amino betaine; cetyl amino betaine; coco amido betaine; coco amido sulfobetaine; oleyl amido betaine, coco imidazoline; coco sulfoimidazoline, cetyl imidazoline, 1-hydroxyethyl-2-heptadecenyl imidazoline; 1-hydroxyethyl-2-mixed heptadecenyl heptadecadienyl imidazoline; n-coco morpholine oxide; decyl dimethyl amine oxide; coco amido dimethyl amine oxide; sorbitan tristearate condensed with ethylene oxide; sorbitan trioleate condensed with ethylene oxide; sorbitan trioleate; sodium or potassium dodecyl sulfate; sodium or potassium stearyl sulfate; sodium or potassium dodecyl benzene sulfonate; sodium or potassium stearyl sulfonate; triethanol amine salt of dodecyl sulfate; trimethyl dodecyl ammonium chloride; trimethyl stearyl ammonium methosulfate; polyoxyethylene/polyoxypropylene block polymers having 10%-80% ethylene oxide (by weight) and a molecular weight of 900 to 16,000; sodium laurate; sodium or potassium myristate; and sodium or potassium stearate.
The polyoxyethylene condensates are particularly convenient in this invention because the HLB of the polyoxyethylene surfactants can be made to vary in a regular fashion depending upon the amount of ethylene oxide condensed onto the hydrophilic portion of the molecule. This facilitates the selection of a primary surfactant having the correct HLB.
While the use of a single surfactant can, in many instances, be sufficient to serve as the primary surfactant in accordance with the process of this invention, the use of a mixed primary surfactant is particularly important in achieving the quick dissolving aspects of the present invention. When selecting a primary or secondary surfactant from a series of polyoxyethylene condensates of nonylphenol, the commercially available condensates may contain, for example, 1, 4 or 9 ethylene oxide units condensed with the nonylphenol. In such a sequence of compounds, a mixture of one part of nonylphenol.multidot.4EO and 1 part nonylphenol.multidot.9EO may prove more effective as the primary surfactant than either nonylphenol.multidot.4EO or nonylphenol.multidot.9EO alone.
As indicated above, the suitability for the primary surfactant for any given oil phase may be tested by a simple procedure. Most conveniendy, a series of related surfactants are considered, such as a series of alkyl alcohols, condensed with varying amounts of ethylene oxide. A small quantity, for example, xc2xc gram of a gram of the putative primary surfactant, is dissolved in several millilters (for example 10 ml) of the oil phase to be dispersed. Where the oil phase to be dispersed is a solution of hydrophobic substance to be dispersed in a solvent, the test should be carried out on that solution. If a clear solution results, a primary surfactant, from the series having a higher HLB (i.e., more ethylene oxide) is selected and the test repeated. When the new surfactant has a sufficiently high HLB, addition of the surfactant will result in a cloudy suspension rather than a clear solution. In this manner, a surfactant (or surfactant mixture) for the oleophilic phase is selected having an HLB not substantially lower than required to render the surfactant soluble in the oil phase.
In practice the surfactants of a series differ by discrete values of HLB. Therefore, in the selection of a surfactant the practical HLB of the first and second members of a series may be too high, and the HLB of the fourth and fifth members of the series will be too low. The third member would be selected, in that case, even though it may not be completely soluble in the oleophilic phase as shown by the simple test.
The hydrophilic-lipophilic balance of a compound is a concept well established in the surfactant field, and generally is used to describe the relative affinities of the hydrophilic and lipophilic moieties that make up the amphoteric molecule. A substance having a high HLB usually has a relatively strong polar group readily soluble in water and a relatively weak lipophilic group. Typically, such substances are soluble in water but not in oils. Conversely, a substance with a low HLB is usually dominated by a large lipophilic group and is soluble in oils. While there have been some attempts to define an HLB scale on the basis of arbitrary solvents, it more practical for purposes of the present invention to test the HLB of the amphoteric surfactants to be used with the particular oil and water phases to be emulsified.
The preferred surfactants useful in the practice of the present invention include a combination of at least one fatty acid ester of a polyoxyalkyleneoxide as the first surfactant, and a fatty acid ester of a monosacharride as the second surfactant.
The emulsifying composition comprises about 5-30 percent of the first polyoxyalkyleneoxide surfactant and about 70 to about 95 percent of the second monosacharride surfactant. The most preferred surfactants useful in the present invention are polysorbate 60, also known as polyoxyethylene 20 sorbitan monostearate, sold under the mark, Tween 60 and sorbitan monostearate, sold under the trademark, Span 60, both of which are commonly used in the food and pharmaceutical industry. The most preferred ratio of polymeric surfactant to monosacharride surfactant is about 1 to about 9.
The preferred microcapsule also comprises in its shell a cellulosic material that facilitates the preferred method of drying the composition, for example by spray drying. The cellulosic material is included in an amount from about one to about 15 percent of the weight of the microcapsule, while the preferred weight is about two to about ten percent. The preferred cellulosic materials include hydroxyl alkyl alkylcellulose and the metal salts of a carboxyalkylcellulose. The most preferred cellulosic materials include hydroxyl propyl methylcellulose and the metal salts of carboxymethylcellulose. The most preferred cellulosic material is the sodium salt of carboxymethylcellulose.
The disaccharide material, the cellulosic material and the emulsifying composition surfactants are all preferably non-toxic, generally accepted as safe for ingestion and pharmaceutically acceptable.
The microcapsule is produced by subjecting a aqueous mixture of the core material, water soluble disaccharide material, emulsifying composition and preferably the spray enhancer to an abrupt pressure change, preferably followed by the removal of the aqueous medium by spray drying.
The mixing of the shell and core material to form a dispersion, or a micro-dispersed or homogenized state, may be accomplished by any of the conventionally known apparatuses including those known as batch mixers, static mixers, motionless mixtures, homogenizer and fluidization equipment. The core and shell materials should be adequately mixed to form a fairly homogenous dispersion of the core and shell materials in the aqueous medium. The micro-dispersion is, on a macroscopic level, generally homogeneous, though not perfectly so.
In order to form capsules by the method of this invention, a homogenized dispersion of core and shell material in an aqueous medium is passed through a pressure pulse apparatus, which can be a microfluidizer, ultra-homogenizer or other high pressure pulse apparatus that impart an abrupt pressure pulse, high shear and/or cavitation forces to the mixture sufficient to promote microencapsulation of the core material. The application of the pressure-pulse may be accomplished by means of a hydraulic pump as described in U.S. Pat. No. 5,271,881, herein incorporated by reference. A preferred apparatus includes a baffle chamber through which the suspension is forced and in which shear and/or cavitation forces impact the suspension.
The function of the pressure pulse apparatus used to form the microcapsules is described briefly as follows. The dispersion of core and shell material is placed in the pump reservoir, and may be conveniently fed under the force of gravity to the open inlet valve permitting the dispersion of core and shell material to flow into the compression chamber. The inlet valve is then closed and high pressure air supplied to a pneumatic motor that drives the piston down into the compression chamber thereby applying an abrupt pressure change to the dispersion of core and shell material contained therein. One or several stroke cycles, consisting of a compression followed by a rarefaction stroke, of the piston may be applied to the dispersion of core and shell in the compression chamber before the exit valve is opened. The impact and withdrawal of piston upon the virtually non-compressible material in compression chamber produces abrupt pressure changes resulting in pressure shock waves, shear forces, and, perhaps, cavitation within the liquid medium. After the dispersion is subjected to these forces, exit valve is opened and the liquid medium flows out of compression chamber into capsule discharge line that leads to the baffle chamber.
A preferred embodiment of the pressure pulse apparatus uses a baffle chamber comprising a section of decreased diameter leading to an inner chamber having baffles that interrupts and delays and increases the turbulence of the flow of the capsule containing mixture.
The baffle chamber is sometimes called the xe2x80x9cstabilization tubexe2x80x9d. As the pump forces the capsule mixture through the stabilization tube, the fluid encounters a reduced diameter channel that increases the velocity of the fluid.

Instant water dissolvable encapsulate and process


A platen has a main body of one material of relatively high durometer elastomeric material having good wear resistance and a low coefficient of friction for sliding on support tubes, and an integral upper support surface of an elastomeric material having a lower durometer and higher coefficient of friction for gripping transported articles. Preferably, the two materials are co-molded to provide an integral platen. Preferably a bead filler is entrained in the main body of the material increasing slidability. Platen apparatus and methods of making the platen apparatus are disclosed.

The present invention pertains to platens used in diverting conveyor systems and more particularly to an improved, longer lasting platen which securely transports a load and is wear resistant.
Diverting conveyors are well known in the art and are frequently used for the sorting or rejection of a series of articles that are being transported along a moving conveyor line. Diverting conveyors are also referred to as diverter tables or slat sorters. Typical diverting conveyors are described in U.S. Pat. No. 5,590,758 to Wilkins et al. and U.S. Pat. No. 3,986,596 to Hamilton. These generally utilize either push blocks or platens to carry articles along the conveyor. Platens utilized in such conveyors are slidably mounted to a series of moving tubes or rails extending between and carried by conveyor side-chains. The platens move with and selectively slide along the tubes in a direction transverse to the motion of the conveyor to define a path in a machine direction for a load thereon. In particular, the tubes are long enough to accommodate platens disposed in at least two paths as they move with the tubes. A follower pin located on the underside of the platen engages a cam, or guide track. A series of switches located at various points along the track are utilized to divert the pins and their associated platens and thus selectively direct successive platens and articles thereon laterally to one or more branches of the track as the platens move with the tubes in a machine direction. The flow of articles along various conveyor paths according to selected or detected parameters is thus provided.
Prior platens have been molded from a single type of plastic and have employed elongated non-skid elements, such as belts or tubes, pressed into grooves on a top surface of the platen for increased friction to better grip transported articles. Other prior platens have utilized a flat non-skid panel that is glued to an ultra-high molecular weight (UHMW) plastic platen body. A drawback of these prior platens is that the pressed belts or tubes tend to become unseated from the grooves and the panels tend to become unglued after a period of use. Such conditions allow articles to slide off the platens, creating the potential for jamming or binding which can damage both the article and the conveyor.
Accordingly, there is a need for a durable platen capable of providing extended service life and which has good wear-resistance and low frictional resistance for sliding on the conveyor tubes, yet also has a higher friction surface for gripping transported articles. Thus, it is an object of the invention to provide an improved diverting conveyor platen. It is another object of the invention to provide an improved diverting conveyor platen that has increased wear resistance, yet easily slides along the support tubes of a diverting conveyor. It is a further object of the invention to provide an improved diverting conveyor platen that does not come apart while in use.
The present invention provides an improved platen for use in diverting conveyor systems. The platen is formed from at least two different types of elastomeric material that are integrally co-molded, co-extruded, or otherwise processed together so as to provide a single unitary component which will not separate under operating conditions. The invention provides an advantage over prior platens in that the high friction support surface will not become unseated or unglued during service, thereby reducing the potential for damage and increasing the service life of the platen, while the body portion easily slides on supporting tubes and is resistant to wear.
The present invention contemplates an integral co-molded platen of two distinct materials. A main body portion is comprised of a relatively high durometer elastomeric material having good wear-resistance and a low friction coefficient for durability and ease of sliding on conveyor tubes. A preferred material is urethane with a hardness in the range of about 70 to 75 Shore-D durometer. A co-molded, integral support surface of the platen is integrally formed with the main body. The support surface is comprised of an elastomeric material which has a lower hardness than the main body and the support surface also has a higher friction coefficient for gripping transported articles. A preferred material is urethane with a hardness in the range of about 70 to 75 Shore-A durometer.
A platen diverting pin or cam follower is located on a bottom surface of the platen for engaging the guide track on a diverting conveyor. The pin can be molded into the body. In a preferred embodiment, however, an insert with a tapped hole is molded into the body and a threaded metallic pin is installed in the insert after the platen has been molded. In this way the pin may easily be replaced in the event that it becomes damaged or worn in service.
In another aspect of the invention, the platen body has beveled edges formed along the leading and trailing edges of the platen to reduce binding against a conveyed article, thereby reducing the potential for damage to the article or the conveyor.
In a further aspect of the invention, the surface of the body is contoured to positively engage the conveyor tubes.
In another aspect of the invention, the support surface includes contours that are formed into it to provide increased gripping of transported articles.
In yet another aspect of the invention, the main body is formed with an elastomeric filler that has lubricating qualities for providing increased slidability and wear-resistance as the surface of the body becomes abraded during use while sliding on the conveyor tubes. In a preferred embodiment, the filler consists of UHMW poly-beads in a matrix of urethane.
A preferred method for making an improved diverting conveyor platen in a mold includes the steps of: (a) positioning a tapped insert in a mold cavity; (b) filling the mold cavity with urethane in the range of 70-75 durometer, Shore D; (c) filling a second mold cavity with urethane in the range of 70-75 durometer, Shore A; (d) closing the mold; (e) applying heat and pressure, (f) opening the mold; and (g) removing the formed integral platen.
Accordingly, the invention provides a durable, integral platen which has a support surface made from a high friction material for gripping transported loads, and which has a main body made from a wear-resistant, low friction material for improved slidability on diverting conveyor tubes. The support surface and the main body are formed into a single, integral unit which will not separate under operating conditions. These and other aspects of the invention will be apparent from the following description, the claims, and the attached drawings.