FIELD OF THE INVENTION
- BACKGROUND OF THE INVENTION
This invention relates to the bleaching of laundry and is especially concerned with bleach products designed for the delivery of a premeasured amount of organic peroxyacid bleach to the laundering bath.
Peroxyacids and their utility as laundry bleaches are well-known in the art. See Canadian Pat. No. 635,620, McCune, issued January 30, 1962, and U.S. Pat. No. 4,100,095, Hutchins, issued July 11, 1978.
It is known that straight chain aliphatic peroxyacids form adducts (inclusion complexes) with urea and that in the adducted form, the peroxyacid has improved stability against loss of available oxygen during storage. See U.S. Pat. No. 3,167,513, van Emden et al., issued January 26, 1965.
The addition of premeasured amounts of peroxyacid bleach precursors to a laundry solution which contains an inorganic persalt is disclosed in U.S. Pat. No. 4,179,390, Spadini et al., issued December 18, 1979. According to this patent, the peroxyacid bleach precursor is coated onto a substrate (such as a nonwoven cloth). The coated substrate article is then added to the laundry bath where the precursor is released and reacts with the persalt to form the highly reactive peroxyacid bleach. The precursor is coated onto the substrate by forming a melt of the precursor or a dispersion of unmelted precursor in a melt of another organic material such as a surfactant or water-soluble polymer, applying molten material to the substrate, and then cooling the substrate to solidify the melt. According to the patent, the-precursor and the inorganic persalt can both be coated onto the substrate, if desired, so long as they are disposed on the substrate in a manner so as to keep them spatially separated from - each other, for example as discrete bands on the substrate
The addition of premeasured amounts of peroxyacid bleach to a wash solution by means of a permeable pouch containing said bleach is disclosed in U.S. Ser. No. 282,483, Bossu, and U.S. Ser. No. 282,562, Bacon et al., both filed July 13, 1981.
It is an object of the present invention to provide a storage-stable article for direct addition of a premeasured amount of organic peroxyacid bleach to the laundry bath.
- SUMMARY OF THE INVENTION
A further object is to provide a process for preparing an article comprising a substrate which carries a peroxyacid bleach and maintains the stability of said bleach.
According to one aspect of the invention, there is provided a laundry additive bleach product comprising:
- a. a substrate in the form of a nonparticulate solid article having disposed thereon,
- b. a urea adduct of an organic peroxyacid compound having the formula:
wherein R is a linear alkylene group of from 4 to - 16 carbon atoms and Y is hydrogen, halogen or a radical selected from
wherein M is hydrogen, alkali metal or ammonium, preferably hydrogen. Preferably R contains from 7 to 12 carbon atoms and Y is hydrogen,
- DETAILED DESCRIPTION OF THE INVENTION
The Peroxyacid Bleach
. A further aspect of the invention is a method of making a laundry additive product, comprising the steps of:
- a. forming a slurry of a urea adduct of a peroxyacid, as defined above, in an aqueous surfactant mixture which contains from 0.5% to about 5% of a surfactant based on weight of adduct;
- b. applying the slurry of (a) to a nonparticulate substrate; and
- c. removing substantially all of the water by evaporation.
The peroxyacid bleaches used in the present invention have the general formula
wherein R is a linear alkylene group of from 4 to 16 carbon atoms and Y is hydrogen, halogen or a radical selected from
wherein M is hydrogen, alkali metal or ammonium. Preferably M is hydrogen
- The Adducts
Representative compounds of the above formula are peroxydodecanoic acid, peroxyhexanoic acid, peroxy- octanoic acid, monoperoxydodecanedioic acid, diperoxydodecanedioic acid, 12-chloroperoxydodecanoic acid, sodium-12-sulfonatoperoxydodecanoic acid. Preferred compounds for use herein are peroxydodecanoic acid and diperoxydodecanedioic acid and mixtures thereof.
For use in the bleach product of the present invention, the peroxyacid bleaches are converted to adducts (also called inclusion complexes) with urea. These adducts can be prepared by treating the peroxyacid bleaches with urea in any known way-for preparing adducts, for example, by mixing them with the urea dissolved in a solvent such as methanol and'isolating the adduct which is formed by crystallization or evaporation. The adduct which is obtained is a crystalline solid. Normally the adduct will comprise 20% to
- The Substrate
25% by weight of the peroxyacid. Preferably the amount of peroxyacid in the adduct will be 25%. All percentages and proportions herein are "by weight" unless specified otherwise.
The present invention requires that the peroxyacid bleach compound be disposed on a substrate which is a nonparticulate solid article. The substrate may itself be water-soluble or water-insoluble and in the latter case it should possess sufficient structural integrity under laundering conditions to be recovered from the laundered fabrics at the end of the laundering process, which may include drying in a hot air clothes dryer. Structures which are water-disintegrable, i.e., that break down in aqueous media to individual fibers or insoluble particles, or structures which disintegrate in a hot air clothes dryer, are not considered satisfactory for the purposes of the present invention.
Water-soluble materials include certain cellulose ethers, alginates, polyvinyl alcohol and water-soluble polyvinyl pyrrolidone polymers, which can be formed into nonwoven and woven fibrous structures or onto films.
Suitable water-insoluble materials include, but are not restricted to, natural and synthetic woven and nonwoven fabrics, foams, sponges and films.
The substrate may have any one of a number of physical forms such as sheets, blocks, rings, balls, rods or tubes. Such forms should be amenable to unit usage by the consumer, i.e., they should be capable of addition to the laundry bath in measured amounts, such as individual sheets, blocks or balls and unit lengths of rods or tubes. Certain of these substrate types can also be adapted for single or multiple uses, and can be provided with loadings of peroxyacid bleach adduct up to an adduct:substrate ratio of 15:1 by weight.
One such article comprises a sponge material releasably enclosing enough peroxyacid bleach adduct to provide bleaching action during several washing cycles. This multi-use article can be made by impregnating a sponge ball or block with 30-60 grams of the adduct. In use, the peroxyacid leaches out through the pores of the sponge into the wash liquor. Such a filled sponge can be used to treat several loads of fabrics in conven-. tional washing machines, and has the advantage that it can remain in the washer after use.
Other devices and articles that can be adapted for use in dispensing the organic peroxyacid bleach in a washing liquor include those described in Dillarstone, U.S. Pat. No. 3,736,668, issued June 5, 1973; Compa et al., U.S. Pat. No. 3,701,202, issued October 31, 1972; Furgal, U.S. Pat. No. 3,634,947, issued January 18, 1972; Hoeflin, U.S. Pat. No. 3,633,538, issued January 11, 1972; Rumsey, and U.S. Pat. No. 3,435,537, issued April 1, 1969.
A highly preferred article herein comprises the adducted organic peroxyacid bleach compound in combination with a sheet and this should be flexible so as to make it compatible with the movement of the fabrics in the washing machine and to facilitate its handling during manufacture of the product. Preferably the sheet is water pervious,.i.e., water can pass from one surface of the sheet to the opposite surface.
If the substrate is a film-type material, perforation of the sheet is desirable. The most preferred form-of the substrate is a sheet of woven or nonwoven fabric or a thin sheet of cellular plastic material (e.g., polyurethane foam). Woven fabric sheets can take the form of a plain weave natural or synthetic fiber of low fiber count/unit length, such as is used for surgical dressings, or of the type known as cheesecloth. Loading limitations of nonwoven sheet type substrates limit the amount of adduct that can be applied to the sheet. Typically the weight ratio- of adduct:sheet is 8:1. Generally a ratio of from - 3:1 to 12:1 is preferable. For a one-time-use article, the size of the article and the amount of adduct disposed thereon should be chosen such that the article contains from . O.lg to ` 2.5g, preferably from 0.2g to l.Og available oxygen.
A desirable feature of a substrate to be utilized in the present invention herein is that it be absorbent in nature. It is known that most substances are able to absorb a liquid substance to some degree; however, the term "absorbent", as used herein, is intended to mean a substance with an absorbent capacity (i.e., values representing a substrate's ability to take up and retain a liquid) of up to approximately 25 times its weight of water.
Determination of absorbent capacity values is made by using the capacity testing procedures described in U.S. Federal Specification UUT-595b modified as follows:
- 1. Tap water is used instead of distilled water;
- 2. The specimen is immersed for 30 seconds instead of 3 minutes;
- 3. Draining time is 15 seconds instead of 1 minute; and
- 4. The specimen is immediately weighed on a torsion balance having a pan with turned-up edges.
Absorbent capacity values are then calculated in accordance with the formula given in said specification. Based on this test, one-ply, dense, bleached paper (e.g., kraft or bond having a basis weight of 52 g/m2, -- has an absorbent capacity of 3.5 to 4; commercially available household one-ply towelling paper has a value of 5 to 6; and commercially available two-ply household towelling paper (a paper structure preferred herein) has a value of - 7 to 9.5. See U.S. Pat. No. 3,686,025, Morton, issued August 22, 1972.
The substrate of this invention can also be defined in terms of "free space." Free space, also called "void volume," as used herein is intended to mean that space within a structure that is unoccupied. For example, certain multi-ply paper structures comprise plies embossed with protuberances, the ends of which are mated and jointed; such a paper structure has a void volume of free space between the unembossed portion of the plies, as well as between the fibers of the paper sheet itself. A nonwoven cloth also has such space between each of its fibers. The free space of nonwoven cloth or paper, having designated physical dimensions, can be varied by modifying the density of the paper or nonwoven cloth. Substances with a high amount of free space generally have low fiber density; high density substrates generally have a low amount of free space. Preferred substrates of the invention herein have up to 90% free space based on the overall volume of the substrate's structure.
As stated above, suitable materials which can be used as a substrate in the invention herein include, among others, sponges, foamed.cellular plastic sheets, paper, and woven and nonwoven cloth.
A preferred paper substrate is a compressible, laminated, calendered, multi-ply absorbent paper structure. Preferably, the paper structure has 2 or 3 plies and a total basis weight of from 23 to 146 g/m2 and absorbent capacity values within the range of 7 to 10. Each ply of the preferred paper structure has a basis weight of 11 to 49 g/m2 and the paper structure can consist of plies having the same or different basis weights. Each ply is preferably made from creped, or otherwise extensible, paper with crepe percentage of 15% to 40% and a machine direction (MD) tensile and cross-machine (CD) tensile of from 15.5 to 232.5 grams per square cm. of paper width. The two outer plies of a 3-ply paper structure of each ply of a 2-ply paper structure are embossed with identical repeating patterns consisting of 2 to 310 discrete protuberances per square cm. raised to a height of from 0.25-mm to 1.00 mm above the surface of the unembossed paper sheet. From 10% to 60% of the paper sheet surface is raised. The distal ends (i.e., the ends away from the unembossed paper sheet surface) of the protuberances on each ply are mated and adhesively joined together, thereby providing a preferred paper structure exhibiting a compressive modulus of from 31 to 124-g/cm3 and Handle-O-Meter (HOM) MD and CD values of from 10 to 130.
The compressive modulus values which define the compressive deformation characteristics of a paper structure compressively loaded on its opposing surfaces, the HOM values which refer to the stiffness or handle of a paper structure, the MD and CD HOM values which refer to HOM values obtained from paper structure samples tested in a machine and cross-machine direction, the methods of determining these values, the equipment used, and a more detailed disclosure of the above paper structure, as well as methods of its preparation, can be found in Wells, U.S. Pat. No. 3,415,459, issued December 3, 1968.
The preferred nonwoven cloth substrates usable in the invention herein can generally be defined as adhesively bonded fibrous or filamentous products, having a web or carded fiber structure (where the fiber strength is suitable to allow carding) or comprising fibrous mats, in which the fibers or filaments are distributed haphazardly or in random array (i.e., an array of fibers in a carded web wherein partial orientation of the fibers is frequently present, as well as a completely haphazard distributional orientation) or substantially aligned. The fibers or filaments can be natural (e.g., wool, silk, jute, hemp, cotton, linen, sisal, or ramie) or synthetic (e.g., rayon, cellulose, or polyesters) or blends thereof.
Methods of making nonwoven cloths are not a part of this invention and being well-known in the art, are not described in detail herein. Generally, such cloths are made by air or water laying processes in which the fibers or filaments are first cut to desired lengths from long strands, passed into a water or air stream, and then deposited onto a screen through which the fiber-laden air or water is passed. The deposited fibers or filaments are then adhesively bonded together, dried, cured and otherwise treated as desired to form the nonwoven cloth. Nonwoven cloths made of polyesters, polyamides, vinyl resins, and other thermoplastic fibers can be spunbonded, i.e., the fibers are spun out onto a flat surface and bonded (melted) together by heat or by chemical reactions.
The absorbent properties desired herein are particularly easy to obtain with nonwoven cloths and are provided merely by building up the thickness of the cloth, i.e., by superimposing a plurality of carded webs or mats to a.thickness adequate to obtain the desired absorbent properties, or by allowing a sufficient thickness of the fibers to deposit on the screen. Any diameter or denier of the fiber (generally up to about 10 denier) can be used, inasmuch as it is the free space between each fiber that makes the thickness of the cloth directly related to the absorbent capacity of the cloth, and which further makes the nonwoven cloth especially suitable for impregnation with an adducted peroxyacid bleach by means of intersectional or capillary action. Thus, any thickness necessary to obtain the required absorbent capacity can be used.
The choice of binder-resins used in the manufacture of nonwoven cloths can provide substrates posessing a variety of desirable-traits. For example, the absorbent capacity of the cloth can be increased, decreased, or regulated by respectively using a hydrophilic binder-resin, a hydrophobic binder-resin or a mixture thereof in the fiber bonding step. Moreover, the hydrophobic binder-resin, when used singly or as the predominant .compound of a hydrophobic-hydrophilic mixture, provides nonwoven cloths which are especially useful as substrates when the precursor-substrate combinations disclosed herein are used in an automatic washer.
When the substrate herein is a nonwoven cloth made from fibers, deposited haphazardly or in random array on the screen, the compositions exhibit excellent strength in all directions and are not prone to tear or separate when used in the washer. Apertured nonwoven substrates are also useful for the purpose of the present invention. The apertures, which extend between opposite surfaces of the substrate can be in a pattern which can be formed during laydown of the fibers to produce the substrate, or by machine-aperturing of the substrate after it is formed. Exemplary apertured nonwoven substrates are disclosed in U.S. Pat. Nos. 3,741,724, Harmon, issued June 26, 1973; 3,930,086, Harmon, issued December 30, 1975; 3,750,237 Kalwaites, issued August 7, 1973; and 3,956,556, McQueary, issued May 11, 1976,
Preferably, the nonwoven cloth is water-laid or air-laid and is made from cellulosic fibers, particularly from regenerated cellulose or rayon, which are lubricated with standard textile lubricant. Preferably, the fibers are from 4.75 mm to 5.1 mm in length and are from 1.5 to 5 denier (Denier is an internationally recognized unit in yarn measure, corresponding to the weight in grams of a 9,000 meter length of yarn). Preferably, the fibers are at least partially oriented haphazardly, particularly substantially haphazardly, and are adhesively bonded together with hydrophobic or substantially hydrophobic binder-resin, particularly with a nonionic self-crosslinking acrylic polymer or polymers. Conveniently, the cloth comprises 70% fiber and 30% binder-resin polymer by weight and has a basis weight of from 12 to 120 , preferably 24 to 36 g/m2.
One preferred example is an air-laid nonwoven cloth comprising 70% regenerated cellulose (American Viscose Corporation) and 30% hydrophobic binder-resins (Rhoplex HA-8 on one side of the cloth, Rhoplex HA-16 on the other; Rohm and Haas Co.). The cloth has a thickness of 4 to 5 mils., a basis weight of 28.7 g/m2
and an absorbent capacity of 6. 30 cm length of the cloth 23 cm wide, weighs 2.0 grams. The fibers are 6.5 mm in length, 1.5 denier, and are oriented substantially haphazardly. The fibers are lubricated with sodium oleate.
A further preferred substrate is a mechanically laid, nonwoven cloth commercially available from Chicopee Mills, Inc., New Brunswick, New Jersey 08903. The fibers are rayon of 1.5 denier and the composition of the nonwoven fabric is 78% rayon and 22% binder. The fabric is uniformly patterned with diamond-shaped holes at 6.45 holes per square cm. The substrate has a basis weight of 34.6 g/m2. 30 cm length of the substrate, 23 cm wide, weighs 2.4 grams. The cloth is sold under the name "Chicopee Keyback 147" by Chicopee Manufacturing Co., Milltown, New Jersey.
A further class of substrate material that can be used in the present invention comprises an absorbent foam-like material in the form of a sheet. The term "absorbent foam-like material" is intended to encompass three dimensional absorptive materials such as "gas blown foams, natural sponges and composite fibrous based structures such as are disclosed in U.S. Pat. Nos. 3,311,115, Mueller et al., issued March 28, 1967, and 3,430,630, Megison et al., issued March 4, 1969,
Synthetic organic polymeric plastics material such as polyether, polyurethane, polyester, polystyrene, polyvinylchloride, nylon, polyethylene and polypropylene are most often employed and a particularly preferred material of this type is a hydrophilic polyurethane foam in which the internal cellular walls of the foam have been broken by reticulation. Foams of this type are described in detail in U.S. Pat. No. 3,794,029, Dulle, issued Feb. 26, 1974, A specific example of this foam type comprises a hydrophilic polyurethane foam of density 0.036 g/cm3 with a cell count of between 8 and 40 cells per cm ., preferably 24 to 32 per cm available from the Scott Paper Company, Eddystone, Pennsylvania, USA, under the Registered Trade Mark "Hydrofoam."
The size and the shape of the substrate sheet are a matter of choice and are determined principally by factors associated with the convenience of its use. Thus the sheet should not be so small as to become trapped in the crevices of the machine or the clothes being washed or so large as to be awkward to package and dispense from the container in which it is sold. For the purposes of the present invention sheets ranging in area from 129 cm2 to 1290 cm2 are acceptable, the preferred area lying in the range of from 516to 1032 cm2 for nonwoven substrates and 193 to 322 cm2 for foamed sheets. Such a size has the additional advantage of being too large to be swallowed by, e.g., small children, thereby minimizing the risk of internal tissue damage from ingestion of the materials absorbed on the substrate.
- Article Manufacture
Preferably, the adduct herein is present on the substrate in combination with a surfactant, the amount of surfactant being from . 0.5% to 5% by weight of the adduct.
In the manufacture of the products of the present invention an aqueous slurry of the urea-adducted peroxyacid bleach compound is first prepared. This can be done by simply mixing the granular adduct with water which contains a surfactant. The amount of surfactant should be from 0.5% to 5% of the weight of adduct. The granules of adduct should have a size of from 0.16 mm to 1.4 mm.. The concentration of adduct in the slurry can be from 20% to 80% based on the total weight of slurry. The concentration of adduct should be chosen so as to use the least amount of water necessary to provide good coating and efficient operation of the coating process, since water must be removed from the coated article in .the final step of the process.
The slurry can be applied to the substrate by any conventional method used to apply a fluid composition to a substrate, e.g.,-by spraying, brushing, spreading with a doctor blade, etc.
A particularly preferred mode of application when the substrate is an absorbent sheet-type material (e.g., absorbent paper or nonwoven cloth) is that which is known as padding. In this method, the slurry of adducted peroxyacid bleach (and any optional materials) is placed into a pan or trough. To the liquid mixture is then added any optional ingredients. A roll of absorbent substrate is then set up on an apparatus so that it can unroll freely. As the substrate unrolls, it travels downwardly and, submersed, passes through the pan or trough containing the slurry at a slow enough speed to allow sufficient impregnation. The absorbent substrate then travels, at the same speed, upwardly and through a pair of rollers which squeeze off excess slurry. The impregnated substrate is then passed through a drying atmosphere to remove most or all of the water. After the drying step, the substrate can be folded, cut or perforated at uniform lengths, and subsequently packaged and/or used.
The rollers used resemble "squeeze rolls" used by those in the paper and papermaking art; they can be made of hard rubber or steel. Preferably, the rollers are adjustable, so that the orifice between their respective surfaces can be adjusted to control the amount of the slurry on the substrate.
In-another exemplary execution of the invention, the slurry of adducted peroxyacid bleach is sprayed onto absorbent substrate as it unrolls. The unrolled substrate web is arranged to move under the spray nozzle at a predetermined speed so as to receive a uniform coating of the slurry.
After the coating steps, the article is subjected to an evaporative drying step (preferably via a moving stream of air) to remove substantially all of the water. By removal of "substantially all of the water" is meant that the article is dried to the point where it is no longer damp to the touch. Generally, the amount of water left on the article will be less than about 0.5% by weight of the article.
- Optional Ingredients
Any of the various known surfactants can be used in preparing the slurry. See McCutcheon's Detergents and Emulsifiers, North American Ed., (1980), incorporated by reference herein. Preferred surfactants are of the anionic type. Typical anionic surfactants are the alkali metal salts of C8-C15 alkyl benzene sulfonates and of C8-C20 alkyl sulfates, C8-C20 alkyl- ethyleneoxide sulfates or paraffin sulfonates. Nonionic surfactants such as fatty alcohol ethoxylates, although operable, are preferably not used since the chemical stability of the peroxyacid bleach'is not as good in the presence of these surfactants.
Various optional ingredients can be included in the products herein. These include perfumes, optical brighteners, germicides, chelators, pH control agents, stabilizers, etc. Such optional ingredients can most conveniently be included by adding them to the aqueous slurry of the adducted peroxyacid bleach prior to application of the slurry to the substrate.
When an optional ingredient is inherently incompatible with the peroxyacid when in intimate contact with peroxyacid during storage, the said ingredient should be separated from the peroxyacid on the substrate. Means for separating incompatible ingredients on a substrate are known. See U.S. Pat. No. 4,179,390, Spadini et al., issued December 18, 1979.
- EXAMPLE I
The invention will be further illsutrated by the following example.
A substrate bleach product designed to deliver about 6 ppm of available oxygen (AvO) from peroxydodecanoic acid to the wash is prepared in the following manner:
- Peroxydodecanoic acid-urea adduct is prepared by mixing a 70% aqueous mixture of peroxydodecanoic acid with finely ground urea, followed by removal of the water by air drying at 50°C . The weight ratio of urea to peroxyacid is 3:1. The dried granular adduct is ground until the particle size is less than 0.42-mm. The adduct contains 1.6% AvO. The coating slurry is prepared at room temperature with 250 grams of the peroxyacid adduct, 15 grams of a 30% solution of sodium lauryl sulfate, - and 150 grams of distilled water. The pH of the slurry is adjusted to 3.0 with the addition of either dilute sodium hydroxide or dilute sulfuric acid solution. 40 grams of the slurry is then applied to a 25 cm by 35 cm sheet of apertured substrate (Chicopee Keyback 147) with a cloth roller. The coated substrate is then fan dried at ambient conditions for about 16 hours. The coated substrate is trimmed to a size of 23 cm by 35 cm and is found to weigh 24.8 grams. The coated substrate contains 1.4% AvO. This article when added to a typical 64 litre laundry detergent solution totally releases the bleach to the solution, providing 6 ppm available oxygen.