Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2001-04-18
2003-06-10
Boyer, Charles (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S444000, C510S445000, C510S446000, C510S276000
Reexamination Certificate
active
06576601
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods of reducing fines in powdered products, and more particularly to a method of reducing fines in powdered textile treating compositions, and powdered textile treating compositions prepared by the method.
2. Description of the Related Art
Household cleaning compositions are often supplied in a liquid or a powdered form. For example, carpet cleaning compositions have been widely available for some time in both liquid and powdered form. Liquid carpet cleaning compositions have typically been the first choice of many consumers. However, because of drawbacks in the liquid compositions, such as a tendency to cause shrinking, matting or wicking of carpet fibers, dry powdered carpet cleaning compositions have become quite popular. Examples of dry powdered carpet cleaning compositions can be found in U.S. Pat. Nos. 4,666,940, 4,552,777, 4,493,781, 4,395,347 and 4,161,449.
However, dry carpet cleaners and certain other powdered household products have a tendency to lose their free flowing properties during storage. For instance, powdered products may become compacted or “caked” due to settling and/or their tendency for absorbing moisture from the ambient air. Caked product is difficult to fill as well as dispense from containers. Therefore, flow agents (also known as anti-caking agents) are often added to powdered compositions in order to keep the powder free flowing.
Flow agents typically contain particles of small size and low density known as “fines” that can readily become airborne. Fines can be very irritating to nasal passages. In addition, a large number of fines in the ambient air can build up a static charge.
In consumer products such as a dry powdered carpet cleaner, fines may be difficult to vacuum. Also, the fines that are removed may not remain trapped inside a typical paper vacuum cleaner bag. As a result, a dust cloud of fines may developed during vacuuming that can be irritating to the nasal passages. In addition, the fines may leave an unsightly residue on shoes, clothing and surfaces in the home.
In the field of dry carpet cleaners, efforts at reducing fines have previously focussed on the incorporation of additional components into the cleaning formulation or the use of screening techniques. For instance, U.S. Pat. Nos. 4,161,449 and 4,552,777 disclose a conventional process for preparing a dry carpet cleaning composition from dry powdered components. These patents mention that a typical dry powdered carpet cleaning composition may include a dry powder inorganic salt carrier, a dry powder anti-caking agent, a liquid fragrance and a liquid dedusting agent. Typical inorganic salt carriers include sodium sulfate, sodium chloride, sodium carbonate, sodium bicarbonate, sodium borate, sodium citrate, sodium tripolyphosphate and sodium nitrate; suitable anti-caking agents include starch, silica powders, grain flours, wood flour, talc, pumice, clays, and calcium phosphates; conventional fragrances are liquid volatile odorous agents including essential oils and aromatic chemicals; and typical liquid dedusting agents may be alkyl phthalates, mineral oil, glycols, ethoxylated alcohols, alcohols, glycol ethers, vegetable oils, naphtha, mineral spirits and naphthalene sulfonates.
In preparing a dry carpet cleaning composition in according with the prior methods described in U.S. Pat. Nos. 4,161,449 and 4,552,777, (1) the dry powders, such as the carrier and the agglomerating agent, are dry blended in a first step, (2) the liquid components, such as the fragrance and any dedusting agent, are separately mixed together in a second step, (3) the mixtures prepared in steps (1) & (2) are admixed, and (4) if necessary, the final product is screened to remove undesirable lumps and fines.
Therefore, it is apparent that the methods described in these patents rely on liquid dedusting agents and screening to control fines in the final dry carpet cleaning product. These extra ingredients (i.e., dedusting agents) or process steps (i.e., screening) increase manufacturing costs, and in the case of screening, may call for measures to control the fines removed by screening.
Thus, further advances are desired to provide a solution to the problem of fines.
SUMMARY OF THE INVENTION
It is envisioned that improved methods of blending and agglomerating powdered products can be used to reduce fines in a final powdered product without the need for dedusting agents or screening techniques. Accordingly, these improved methods can be used to produce a particulate textile fiber or fabric cleaning composition that satisfies the need for a dry textile cleaning composition that has a minimal level of fines.
Agglomeration is the process of bringing together fine powders or particulates into larger masses with pressure, agitation and/or other mechanisms. Agglomerating techniques include: (1) pressure compacting, such as briquetting, tableting and using a pellet mill; (2) tumbling or granulation; and (3) spray congealing. In the context of dry powdered or particulate household cleaning chemicals, tumbling or granulation is typically the process of choice.
A method is disclosed for producing a particulate textile fiber or fabric cleaning composition that includes the steps of introducing at least one particulate material into a mixing vessel, introducing at least one liquid material into the mixing vessel to form a mixture, blending the mixture for a first time period, chopping the mixture for at least a portion of the first time period, and thereafter blending the mixture without chopping for a second time period. The method produces a particulate fabric cleaning composition having acceptable flow characteristics yet results in a reduced level of fines without the need for a screening step to remove fines. For the purposes of this patent, fabric includes natural and/or synthetic fiber products such as carpets, upholstery, drapes, and even clothing.
Without intending to be bound by theory, it is believed that chopping creates greater surface area (which is otherwise lessened by mixing liquid with solids) and that the greater area permits fine particles of the particulate materials (such as silica fines in a dry carpet cleaning composition) to become attached to the larger particles in the mix by agglomeration. Note that this is surprising as chopping might have been expected to increase dust/fines. Also, in the method of the present invention, the inclusion of a time period of blending and chopping the mixture serves to agglomerate particles and at the same time break up any large agglomerated particles that might clog the container. In other words, the blending serves to agglomerate smaller particles while the chopping serves to breakup larger oversized agglomerations. This helps to distribute any liquid materials and to create additional exposed sticky surfaces to which fines may attach. It is particularly desirable to reduce particles in the size range of 200 mesh (0.074 mm opening) and finer.
The chopping process is a high shear mixing that generally shears large agglomerated particles at the liquid interface between particles. However, individual particles may shear through the particule body. Therefore, as used herein, the term “chopping” refers to an action that can shear particle agglomerations at a liquid-solid interface or a solid-solid interface.
The step of introducing liquid material into the mixing vessel and the step of blending and chopping the mixture for a first period of time may all be performed simultaneously. Although the liquid material may be added to the mixing vessel in any manner, it is preferred that the liquid materials be introduced into the mixing vessel at a uniform flow rate, most preferably by a sprayer that provides a spray in order to produce a uniform powder.
As used herein, the term “acceptable flow characteristics” for a fabric cleaner means that the composition may be dispensed without clogging from conventional shaker-type containers that are widely used for packaging household cleani
Mikic Thomas
Rodriguez Dolores T.
Schramm Heather R.
Weitkuhn Hans J.
Boyer Charles
S. C. Johnson & Son Inc.
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