HK1036640A - Dry cleaning method and modified solvent - Google Patents

Description

Dry cleaning method and improved solvent

The present invention belongs to the general field of dry cleaning of garments, fabrics, textiles and the like, and is a more unique method and apparatus for dry cleaning fabrics using a modified solvent that has not been used before.

Background of the invention

Dry cleaning is an important industry throughout the world. There are 4 thousands of dry cleaners in the united states alone (many of which have chains), which are an indispensable industry in today's economy. Many garments (and other articles) must be dry cleaned to remove body oils and keep clean while preventing shrinkage and discoloration.

The dry cleaning agent generally used so far is Perchloroethylene (PERC). Its use presents a number of disadvantages including its own toxicity and odor.

Another problem that exists in the art is that different fabrics require different systems to prevent the fabrics from being damaged during dry cleaning.

Previous dry cleaning processes have involved the use of various solvents and suitable machinery to accomplish the washing. As previously mentioned, the most commonly used solvent in the past was perchloroethylene. Perchloroethylene has a very good washing effect, but has the main defects of health hazard and environmental pollution. Its use can lead to many types of cancer, contamination of groundwater, damage to aquatic life. In some areas, perchloroethylene is banned due to its hazardous nature. In addition, other solvents such as petroleum-based solvents, glycol esters, ethers have also been tried in the past. The cleaning effect of the various solvents and the suitability for use with fabrics can be analogized to perchloroethylene.

The dry cleaning industry has long relied on petroleum-based solvents, and notably chlorinated hydrocarbons, perchloroethylene and trichloroethylene, to clean textiles and garment materials. Since the twenty-century and the forty years, perchloroethylene has been praised as nonflammable, powerful decontamination and ideal washing effect, and is particularly suitable for the synthesis of dry cleaning industry. In the early seventies of the twentieth century, perchloroethylene was found to be causative of animal liver cancer. This is a panic finding because of the discharge of sewage, the accumulation of waste products, in the dry cleaning industry, which can cause the infiltration of pollutants into the soil and groundwater.

Increasingly stricter regulations are being applied by environmental protection agencies, eventually in 1996 requiring all dry cleaners to adopt a "dry-to-dry" cycle, i.e. the textiles and garments are fed in and out of the machine in a dry state. This requires closed loop system operation to recover most liquid and gaseous perchloroethylene. This "cycling" process involves placing the fabric items and items into a specially made washing machine that can hold 15-150 pounds of fabric items and items with a circular viewing window. Before being put into a washing machine, the dirt of the fabric or the clothes needs to be manually checked. If the fabric is of a very unusual or difficult to handle texture, the label is inspected to determine if the product is deemed suitable for dry cleaning by the manufacturer. If this is not done, permanent stains may result. For example, a sugar stain is not easily detected, but is oxidized to become brown upon dry cleaning. If the stain is oily, water will not work, and perchloroethylene can dissolve the oil. In fact, the main reason for the dry-cleaning method used for some garments, which are not suitable for conventional washing machines, is to remove the accumulated body-secreted oils (such as fatty acids), which are prone to oxidation and thus generate foul odors.

The grease accumulated in the solvent is removed by a filter, and perchloroethylene is recovered. In other words, the contaminated perchloroethylene is distilled and condensed into a cleaning liquid. A small amount of detergent, usually 1% to 1.5% of the total volume of the mixture, is typically mixed with perchloroethylene to aid in the dissolution of the stain and/or pre-stain removal.

The washing machine becomes a dryer before the laundry is taken out of the machine. The hot air is blown into the box body, and is not exhausted outwards any more, but instead, the air flow enters a condenser to liquefy perchloroethylene steam for recycling. After washing and drying, the clothes are ironed flat.

The dry cleaning process has removed most of the perchloroethylene from the garments, but a small amount remains. Some clothing fibers retain more solvent than other types of fabrics. For example, natural fibers such as cotton and wool, heavy fabrics such as sleeping bags, velvets, shoulder pads, etc., have more residual solvent than light and thin fabrics or rayon.

Another important problem related to dry cleaning of garments is the fastness of the coloration of the dyes used. Perchloroethylene is a very aggressive detergent and typically dyes used by garment manufacturers are susceptible to discoloration in perchloroethylene or other dry cleaning solvents. Sometimes, the fabric is provided with a label which can only be dry-cleaned, but the printing or surface dye of the fabric is easy to fade and is not durable. When certain fabrics fade during washing, other fabrics become colored.

Another problem related to dry cleaning of fabrics is the re-precipitation of water-soluble soils dislodged from the garments or fabrics, which can precipitate onto other garments or fabrics being cleaned. Silicone-based detergents, which are volatile only, are very effective in dissolving fats, oils and other organic materials from laundry and keep them suspended, but do not keep water-soluble materials suspended without the aid of suitable cleaning aids.

The same problem exists for perchloroethylene and other hydrocarbon-based solvents. Special cleaning agents have been developed to solve the problem of water-soluble materials being suspended in organic solvents and re-precipitating therefrom. The cleaning aids used for perchloroethylene are different from those used for volatile silicone detergents.

The only cyclic siloxane component described for washing purposes is disclosed by Kasprzak in U.S. patent No. 4,685,930. However, the disclosure is filed only for spot cleaning. There is neither disclosure of soaking laundry in cyclic siloxanes nor any suggestion of using cyclic siloxanes in dry cleaning machines. Furthermore, there is no suggestion of a continuous process such as soaking the textile in cyclic siloxane, agitating, spinning, partially vacuuming and heating to dry, clean the laundry in a batch manner, and remove fats, grease and other soils from a large volume of laundry.

The present invention comprises a dry cleaning system and method, and in the present invention, the dry cleaning machine is used in combination with a specialized solvent derived from an organic/inorganic hybrid (silicone). Among such silicone resins are a group known as cyclic siloxanes. The cyclic siloxane-based detergent makes the system more environmentally friendly and more effective in washing fabrics, etc. The silicone component is used in a dry cleaning machine to carry out the method of the present invention. To improve the detergency of the cyclic siloxane-based detergent, the solvent is modified with a chemical selected from the group consisting of 2-ethylhexyl acetate, esters, alcohols and ethers. In a preferred embodiment, the process comprises the steps of: placing the laundry in a wash basket; agitating the laundry, and the laundry is soaked in the modified siloxane component; removing a substantial portion of the siloxane component; centrifugally drying the clothes; after cooling, the laundry is taken out of the basket.

Brief description of the drawings

The foregoing advantages of the invention, as well as additional objectives and related advantages, will be readily understood by reference to the following detailed description of the preferred embodiments when read in conjunction with the accompanying drawings.

Fig. 1 is a block diagram illustrating an embodiment of the present invention.

Detailed Description

The present invention comprises a method and apparatus for dry cleaning fabrics which are washed with a silicone-based detergent having a flash point value (in excess of 140F DEG), which does not damage the fabrics (does not discolor, does not shrink) and which has excellent solvency for fatty acids, greases during dry cleaning.

The dry cleaning process, which uses a liquid cyclic siloxane, is commonly used in cosmetics and pharmaceuticals. The following cyclic siloxanes are more unique: octamethylcyclotetrasiloxane (tetramer), decamethylcyclopentasiloxane (pentamer), dodecamethylcyclohexasiloxane (hexamer).

The solvent of the present invention is environmentally friendly, does not precipitate or accumulate in clothing, has low allergenicity, and is unique in flammability. In use, the solution has a flash point and a fire point that are at least ten degrees Fahrenheit apart, so that the solvent self-extinguishes between the flash point and the fire point. Further, the solvent can be heated (above 100 degrees Fahrenheit) without causing fabric damage, further increasing the washing speed. Finally, the solvent has a tension of less than 18 dynes per square centimeter, better penetrates the fabric fibers, removes stains, and more easily removes residual solvent from the fabric.

The present invention discloses volatile silicone resins as alternative solvents to the common petroleum-based aliphatic compounds and halogenated hydrocarbons. Silicone resin does not exist in nature, and the silicone resin must be prepared manually. The initial material is sand (silica), or other inorganic silicates, which account for 75% of the proportion in the crust. Silicone resins were first synthesized in 1863 from Firedel and Crafts, which first produced tetraethylsilane. In the next few years, despite the synthesis of many other derivatives, until the fortieth of the twentieth century, there has been widespread interest in silicone resin chemistry.

Silicon is an electropositive element capable of forming covalent bonds with carbon and other elements, including halogens, nitrogen, oxygen, and the like. The strength and activity of the silicone depends on the nature of the electronegative elements that form the covalent bonds of the silicone. The polysilane is hydrolyzed according to certain conditions to form polysiloxane. These cyclic and linear polymers are commercially known as silicone fluids (silicone fluids).

Silicone fluids are non-polar, insoluble in water and lower alcohols, completely soluble in typical aliphatic and aromatic solvents, including halogenated solvents, but only partially soluble in petroleum middle distillates such as naphthenes. The silicone fluid is insoluble in higher hydrocarbons, lubricating oils, paraffin, fatty acids, vegetable oils, animal oils, and the like. While volatile cyclic silicone fluids (tetramers and pentamers) are slightly soluble in higher hydrocarbons.

In fact, it has been unexpectedly found that the use of cyclic siloxanes reduces discoloration and cross-staining when the cyclic siloxanes are applied as dry cleaning agents to conventional dry cleaning equipment. The applicant has further found that the problem of discoloration caused by the usual solvents is virtually eliminated, thereby gaining a great economic benefit to the dry-cleaning operator. This benefit is expressed in that the dry cleaner does not have to consider the color of the laundry in the mixed washing, thereby greatly improving the washing productivity.

Alternatively, volatile silicone resins (cyclic) may be combined with ester additives, with 2-ethylhexyl acetate (EHA) being particularly preferred to provide strong solvency and detergency.

In the degreasing force test of the volatile cyclic silicone resin/2-ethyl acetate mixture, the effect is better than that of a petroleum-based aliphatic solvent and is comparable to perchloroethylene. Perchloroethylene is a good deep degreaser, but it is too effective for ordinary dry cleaning. The main purpose of dry cleaning is to remove dirt and fatty acids that accumulate during wearing and produce unpleasant odors. An ideal dry cleaning agent should not discolor the material being cleaned, dissolve the plastic, or change its color or texture due to too strong an effect.

The volatile cyclic silicone resin, in combination with certain organic esters, ethers, and alcohols, can achieve many unique physical and chemical properties that are not comparable to conventional solvents. Decamethylcyclopentasiloxane, and 2-ethylhexyl acetate are preferred, which are particularly desirable degreasing agents for a number of reasons, said degreasing agents being chemically inert to the dyed textile fibers, whether natural or synthetic. This means that the solvents do not cause the problems of cross-staining and discoloration that are associated with the prior art solvents.

The balanced molecular weight of the volatile cyclic siloxane and the ester compound gives it the desired surface tension, which is very important for washing. Another important aspect is that the volatile cyclic silicone fluid imparts a "soft, soft hand" to virtually all fabrics. This property is important because perchloroethylene degreases natural fibers, making the fabric feel rough.

The cyclic molecular structure makes the oxidation resistance of the material superior to that of petroleum-based materials. This makes distillation of the cyclic siloxanes more reliable. The ring structure facilitates the penetration of liquid into the fibers of the clothing material for the removal of dirt.

The two major cyclic siloxanes, tetramer and pentamer, have a wide freezing point range, ranging from the tetramer freezing point of 53 degrees fahrenheit to the pentamer freezing point of-40 degrees fahrenheit, with a temperature differential of nearly 100 degrees fahrenheit. Each of the materials described has unique physical properties and is not suitable for use alone as a dry cleaning degreasing solvent. For example, the flash point of the tetramer is 140 degrees Fahrenheit but the ignition point is 169 degrees Fahrenheit, and the flash point of the pentamer is 170 degrees Fahrenheit and 190 degrees Fahrenheit but the ignition point is 215 degrees Fahrenheit. The tetramer and pentamer can be mixed together to produce a desired composition or formulation having desired combustion characteristics and freezing point. The preferred ester additive, 2-ethylhexyl acetate, also has a high flash point and a very low freezing point.

Thus, a preferred mixture is less than 40% 2-ethylhexyl acetate, and more than 50% pentamer. This range is suitable for most dry cleaning operations. While 2-ethylhexyl acetate is the preferred material, it can be selected from a wide variety of materials, such as esters, ethers and alcohol families, which have similar properties to the materials described above. The following list of compounds may be used to replace 2-ethylhexyl acetate in the preferred mixture:

esters as pesticides

Dibasic esters

Glycol ether DPM acetate

Glycol ether EB acetate

Alcohols

2-ethylhexyl alcohol

Cyclohexanol

Hexanediol

Ethers

Glycol ether PTB

Glycol ether DPTB

Glycol ether DPNP

Although only a limited number of volatile organocyclic siloxane additives are listed above, none are within the scope of the invention.

It should be noted that certain additives, such as petroleum-based derivatives, i.e., solvent oils, halogenated hydrocarbons, should be added to the above formulations to achieve certain cleaning and/or degreasing effects that are not possible using the above components alone.

The following are listed as the above-mentioned various material components:

component 1:

tetramer-75% by weight

2-ethylhexyl acetate (EHA) -25% by weight

And (2) component:

2-ethylhexyl acetate (EHA) -50% by weight

Pentamer-50% by weight

And (3) component:

2-ethylhexyl acetate (EHA) -30% by weight

Pentamer-70% by weight

And (4) component:

tetramer-15% by weight

Pentamer-55% by weight

2-ethylhexyl acetate (EHA) -30% by weight

And (5) component:

2-ethylhexyl acetate (EHA) -85% by weight

Pentamer-15% by weight

Although the above components are based primarily on volatile organocyclosiloxane and 2-ethylhexyl acetate (EHA), the following component compounds are also within the scope of the present invention:

2-ethylhexyl acetate (EHA) -1-99% by weight

Pentamer-1-99% by weight

Tetramer-accounts for 1-99% of the weight

The combination with the aforementioned solvents, or itself, may be modified or enhanced in one embodiment of the dry cleaning process of the present invention. The improved form is as follows: adding sand suspension additive to prevent dirt such as dust from re-precipitating in the washing and rinsing processes; adding a water-soluble stain cleaning agent; and a sterilizing and disinfecting agent to eliminate all microorganisms and bacteria present in the laundry. The additive may be a solvent component or may be a separate formulation.

A suitable cleaning agent, compatible with silicone solvents, is disclosed and forms part of the present invention. The cleaning agent consists of an amphiphilic molecular structure, has a highly lipophilic straight chain or cyclic organosiloxane main chain and a hydrophilic polar side chain, can replace and form a pure organic molecule or is mixed with organosiloxane molecules, and has 1-300 mol of polar finger-shaped particles. The polar finger particles may be in the form of ions. Further, an ionic surfactant may be used in combination with a solvent.

The preferred cleaner formulation for the volatile silicone solvent should have the following molecular characteristics, either in whole or in combination with other components:

1. an amphiphilic molecular structure consisting of a highly lipophilic linear or cyclic organosiloxane backbone substituted with hydrophilic polar side chains or with an array of finger-like particles on the backbone.

2. Each molecule having 1-300 moles of polar finger particles.

3. The polar finger particles comprise 20% to 90% by weight.

4. Hydrophilic substance: the lipophile ratio (HLB) was 4 to 18.

5. By reaction with ethylene oxide and/or propylene oxide, polyethers are produced which constitute the hydrophilic finger-like particle substituents on the lipid backbone.

Examples of the use of organosilicate backbones as material components are as follows:

1. finished cyclic organosiloxanes available from the general electric siloxanes department, new york, waterburry, known under the product names:

SF-1288 (Cyclic organosiloxane backbone; 66% by weight ethylene oxide polar finger particles)

SF-1528 (cyclic organosiloxane backbone, 24% by weight of ethylene oxide and propylene oxide polar finger particles; dissolved (10% to 90%) in pentamer).

SF-1328 (organosiloxane backbone; 24% by weight of ethylene oxide and propylene oxide polar finger particles; dissolved (10% to 90%) in a mixture of tetramer and pentamer).

SF-1488 (organosiloxane backbone; 49% by weight ethylene oxide polar finger particles).

2. Finished organosilicones are available from sinugonin corporation under the midland mi product name:

3225C (organosiloxane backbone; ethylene oxide and propylene oxide polar finger particles, dissolved in chloromethicone).

3. A series of linear organic polyethers with ethylene oxide polar finger particles are available from air products and Chemicals under the product name Allentown PA:

surfynol 420 (ethylene oxide polar finger particles, 20% by weight).

Surfynol440 (ethylene oxide polar finger particles, 40% by weight).

Surfynol 465 (ethylene oxide polar finger particles, 65% by weight).

The preferred cleaning agent is an 80: 20 ratio of GE SF-1528 and Surfynol 440.

The above categories are the basic preferred cleaning agents used in conjunction with volatile silicone solvents.

This disclosure is intended to illustrate that volatile silicone solvents should be used in conjunction with the cleaning agent to meet the industry-required dry cleaning parameters.

Preferred detergent parameters are as follows:

SF-1328 (50% -90% by weight), and Surfynol 420 (50% -10% by weight)

SF-1328 (70% -95% by weight), and Surfynol440 (30% -5% by weight)

SF-1328 (60% -95% by weight), and SF-1488 (40% -5% by weight)

SF-1528 (60% -95% by weight), and Surfynol 420 (40% -5% by weight)

SF-1528 (70% -95% by weight), and Surfynol440 (30% -5% by weight)

SF-1528 (60% -95% by weight), and SF-1488 (40% -5% by weight)

SF-1528 (50% -85% by weight), Surfynol440 (49% -5% by weight) and SF-1288 (1% -10% by weight)

SF-1528 (50% -70% by weight), Surfynol440 (49% -5% by weight) and SF-1488 (1% -25% by weight)

It should be noted that the formulations and materials described above are merely examples of cleaning agents that may be used to achieve the desired results. Any organic and/or organo-siloxane based cleaning agent, such as the aforementioned plurality of organic and/or inorganic organo-siloxane compounds, may be used and may be used in conjunction with other related cleaning agents, provided that it is compatible with the volatile siloxane dry cleaning solvents, removes water soluble dirt from the fibers, and prevents re-precipitation during dry cleaning.

The following steps are described with particular reference to dry cleaning process embodiments.

In step 1, garments, or other items to be dry cleaned, are placed in a vertical washing and drying machine with a horizontal agitated wash basket (well known to those skilled in the art). The basket has a plurality of holes, preferably 1/8-1/2 inches in diameter per hole. The reason for this size is to utilize the low surface tension characteristic of cyclic siloxanes by direct spin drying by centrifugal force.

In step 2, a wash cycle is introduced into the solvent consisting of the cyclic siloxane tetramer and pentamer. The preferred combination is 80% tetramer and 20% pentamer by weight. Additionally, the cyclic siloxane solvent can comprise any of the compositions previously described. The additives used to condition the mixture may be added prior to the wash cycle and need not be part of the solvent. The additives, i.e., the detergent and suspending agent, allow the solvent to complete the entire washing process of the garment. Solvent and detergent (if used) are pumped from the storage tank into the wash basket. The washings are agitated, the laundry is mechanically rubbed and the penetrating solvent removes dirt and body fat from the fabric fibres, said agitation being continued for 1-15 minutes. During the wash cycle, solvent and detergent (if used) are pumped out of the wash basket through a valve and then through a filter. The filter system helps remove particulates and contaminants from the mixture. When "batch" is selected, the solvent stream is reused and the mixture is not passed into the filter system and is pumped from the valve directly back into the wash basket. Alternative forms are: any type of cartridge, disk, hose, or tube, used alone or in combination. Alternatively, the filter structure is additionally constructed of activated carbon or diatomaceous earth.

In step 3, the clothes, etc. are washed, the mixture is pumped from the wash basket into a work tank, or retort, where the clothes, etc. are centrifuged to remove as much of the mixture as possible, and the remaining mixture is pumped, or gravity fed, into the destination device. The centrifugal force process lasts for 1-7 minutes according to specific conditions, and the rotating speed is more than 350 Revolutions Per Minute (RPM); preferably 450 rpm to 750 rpm. This process results in residual solvent in the wash not exceeding 2-5%, typically 3%. The higher the rotation speed, the more centrifugal force acts on the rotating basket and the faster the solvent removal speed. The low surface tension of the solvent maximizes the effectiveness of the solvent removal during centrifugation.

In steps 4 and 5, the garment is tumbled in a basket and heated to 110 and 170 degrees Fahrenheit. The measured temperature is the pre-condensation point temperature of the steam-containing air present in the wash basket. Pressurized steam is injected through the coiled pipe, and a circulating ventilator is used for heating air in the clothes containing basket to complete the heating process. At the same time, a partial vacuum can be created in the machine, providing a negative pressure of 50-600 mmhg (760 mmhg atmospheric pressure), thus lowering the vaporization point of the components and reducing the time. In this heating cycle, the solvent mixture is vaporized and carried by the circulating air into the condensing coil, and the vapor in the main gas stream is condensed into a liquid state for collection. The gas stream may be reheated in a closed loop system. Generally, the solvent mixture is removed from the washings for 10-55 minutes and recycled.

In step 6, the heating cycle is stopped and the cooling cycle is started. The cooling cycle may take 1-10 minutes. The temperature will drop from 110 f to 170 f to 100 f, with a preferred range of 70-100 f. The process is to circulate air in the cooling pipe by removing heat until the cooling process is completed. The air is simply circulated through the heating tubes, except that no steam is passed through the heating tubes. After cooling, the clothes are taken out, and wrinkling can be reduced. When the temperature is high, the film is taken out, and wrinkles are caused.

In step 7, the soiled siloxane is reprocessed and cleaned by liquid ring pump (liquid ring pump) or venturi with additional fans. This process is accomplished by: the dirty solvent is pumped into the vacuum still and the vacuum still process of draining the tank is the process of assisting drying. The heat energy is provided by the steam heating pipe contacting with the expansion slot, and the temperature range is 230-300 degrees Fahrenheit.

Cyclic siloxanes have boiling points in excess of 150 degrees fahrenheit. For example, tetramers have boiling points in excess of 175 degrees fahrenheit and pentamers have boiling points in excess of 209 degrees fahrenheit. Distillation of the siloxane at normal boiling points without vacuum results in decomposition of the chemical species, i.e., above 150 degrees fahrenheit, the cyclic structure is cleaved to a linear structure resulting in the formation of formaldehyde. In one embodiment of the invention, the device for purifying and recovering the used cyclic siloxane is provided with great economic benefits, and can keep the cyclic structure complete and recover the regenerated solvent. The used cyclic siloxane solvent is vacuum distilled to remove low boiling impurities, including residual water, as well as high boiling impurities.

It has been found that cyclic siloxanes, i.e., tetramers and pentamers, form azeotropic mixtures at low temperatures, such as 209 degrees fahrenheit, resulting in pure water, pure solvent, and soluble impurities in the solvent collectively constituting a residue.

While various embodiments have been described above, it should be noted that the invention is not limited thereto. Thus, the scope of the preferred embodiments should not be limited by the examples described above, but should be defined by the following claims and their equivalents

Claims (14)

1. A method for dry cleaning articles comprising the acts of: (a) immersing articles to be dry cleaned in a composition comprising a silicone solvent and a chemical selected from the group consisting of 2-ethylhexyl acetate, esters, alcohols and ethers; (b) agitating said article in said composition; and (c) excluding the composition from said article.

2. The method of claim 1, wherein the composition comprises a siloxane solvent selected from the group consisting of pentamers, tetramers, and hexamers of cyclic siloxanes.

3. The method as recited in claim 1, wherein said chemical comprises 2-ethylhexyl acetate.

4. The method of claim 3, wherein said siloxane solvent comprises a tetrameric cyclic siloxane.

5. The method of claim 4, wherein the tetrameric cyclic siloxane is expressed at 75% by weight and the 2-ethylhexyl acetate is expressed at 25% by weight.

6. The method of claim 3, wherein said siloxane solvent comprises a pentamer cyclic siloxane.

7. The method of claim 6 wherein the pentamer cyclic siloxane is expressed as 60% and 80% by weight and the 2-ethylhexyl acetate is expressed as 20% and 40% by weight.

8. The method of claim 6, wherein the pentamer cyclic siloxane is expressed as 50% by weight and the 2-ethylhexyl acetate is expressed as 50% by weight.

9. The method of claim 6 wherein said pentamer cyclic siloxane comprises 15% by weight and said 2-ethylhexyl acetate comprises 85% by weight.

10. The method of claim 3, wherein the siloxane solvent comprises a pentamer cyclic siloxane and a tetramer cyclic siloxane.

11. The method of claim 10, wherein said tetrameric cyclic siloxane is 15% by weight, said pentamer cyclic siloxane is 55% by weight, and said 2-ethylhexyl acetate is 30% by weight.

12. The method of claim 1, wherein the chemical comprises an ester selected from the group consisting of dibasic esters, glycol ether DPM acetate, and glycol ether EB acetate.

13. The method of claim 1 wherein said chemical comprises an alcohol selected from the group consisting of 2-ethylhexyl alcohol, cyclohexanol, and hexylene glycol.

14. The method of claim 1, wherein the chemical comprises an ether selected from the group consisting of glycol ether PTB, glycol ether DPTB, and glycol ether DPNP.