HK1191366A - N-propyl bromide based solvent compositions and methods for cleaning articles - Google Patents

Description

N-propyl bromide-based solvent compositions and methods for cleaning articles

Technical Field

The present invention relates generally to the field of cleaning articles using n-propyl bromide based solvent compositions.

Background

Various methods and solvent compositions are known for cleaning articles such as metals, aerospace parts, medical devices, photographic and motion picture films, electronic and mechanical parts, molds for casting plastics, surfaces prepared for painting, and various substrates that require degreasing, including plastic and elastomeric surfaces. While chlorine-containing solvents are technically suitable for cleaning articles, many of them have now been severely limited due to environmental and/or health considerations. The need for non-chlorinated high performance detergents that can be used in a safe and effective manner has led to the development of n-propyl bromide solvent compositions.

N-propyl bromide (also known as 1-bromopropane, propyl bromide, or NPB) is now considered an environmentally friendly solvent. It is a commercial product particularly useful in cold cleaning and/or vapor degreasing processes. Solvent compositions comprising n-propyl bromide and additives/stabilizers are well known in the art. Some commonly used additives/stabilizers include naphthas, nitriles, ketones, esters, glycols, ethers, carbonates, glycolic acid, basic hydroxides, amines, epoxides, nitroalkanes, and mixtures thereof. However, these and other methods are not suitable for removing at least one of water or water-soluble contaminants.

Water has very low solubility in n-propyl bromide. Thus, when cleaning items having water and/or water-soluble surface contaminants, n-propyl bromide-based solvents are typically mixed with water by agitation in an attempt to remove the surface contaminants. However, mixtures of NPB with water tend to form emulsions that are difficult to separate. The decomposition of n-propyl bromide is another problem with existing solvent systems based on n-propyl bromide. N-propyl bromide readily reacts with water, and if an excess of water is present in a solvent based on n-propyl bromide, n-propyl bromide decomposes at a rate of more than five times its normal decomposition rate. Furthermore, waste treatment of emulsions of n-propyl bromide, water, and surfactant requires a lot of energy and is equipment intensive.

Thus, there is a need for n-propyl bromide-based solvents for removing water and/or water-soluble surface contaminants that have good separation characteristics and relatively low decomposition rates upon reaction with water.

Summary of The Invention

The present invention provides these solvent compositions comprising from about 50 to about 99 weight percent n-propyl bromide, from about 0.5 to about 50 weight percent alcohol, and at least 0.005 weight percent surfactant.

The present invention provides a method for removing at least one of water or water-soluble contaminants from an article. The method utilizes a solvent composition comprising about 50 to about 99 weight percent n-propyl bromide, about 0.5 to about 50 weight percent alcohol, and at least 0.005 weight percent surfactant.

The solvent compositions and methods of the present invention are useful for removing at least one of water or water soluble contaminants from metal products, glass products, plastics, polymer substrates, electronic components, and combinations thereof.

The solvent compositions and methods of the present invention are useful for cleaning. The term "cleaning" as used herein means cold cleaning and/or hot rinsing; the term "cold clean" means rinsing with a solvent at ambient temperature; and the term "hot rinse" means rinsing with condensed solvent. Herein, the terms "solvent" and "solvent composition" are used interchangeably.

Further features and advantages of the invention are described in detail below with reference to the accompanying examples.

Detailed Description

The present invention provides n-propyl bromide-based solvent compositions and methods for cleaning articles. The solvent composition of the present invention comprises about 50 to about 99 weight percent n-propyl bromide, about 0.5 to about 50 weight percent alcohol, and at least about 0.005 weight percent surfactant. The solvent compositions and related cleaning methods of the present invention can be used to remove at least one of water or water soluble contaminants from an article. In various aspects of the invention, cleaning is performed by either a cold cleaning or a hot rinsing process.

The amount of n-propyl bromide used in the solvent compositions of the present invention may be from about 80 weight percent to about 98 weight percent, or from about 88 weight percent to about 95 weight percent.

The alcohol used in the solvent composition of the present invention is an aliphatic monohydric alcohol. The alcohol may be selected from the group consisting of: 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-heptanol, 1-hexanol, and pentanol, including mixtures thereof.

The surfactant used in the solvent composition of the present invention may be selected from the group consisting of: the products of the reaction between the nonionic surfactant, the fatty acid reactant, and the amine reactant (fatty acid-amine), including mixtures thereof. The fatty acid reactant may be selected from the group consisting of: containing C₆To C₁₂Including mixtures thereof. The fatty acid may be caproic acid or capric acid. The amine reactant for use in the present invention may be selected from the group consisting of: containing C₆To C₁₂Including mixtures thereof. The amine may be laurylamine. The fatty acid amine resulting from an equivalent reaction between fatty acid and amine may be a compound resulting from an equivalent reaction between caproic acid and oleylamine, or a compound resulting from an equivalent reaction between capric acid and oleylamine, or a compound resulting from an equivalent reaction between caproic acid and laurylamine, or a compound resulting from an equivalent reaction between capric acid and laurylamine.

The nonionic surfactant for use in the present invention may be selected from the group consisting of: polyoxyethylene alkyl ethers, polyoxyethylene secondary alcohol ethers, and polyoxyethylene alkylphenyl ethers, including mixtures thereof. For example, SOFTANOL may be used.

Biodegradable nonionic surfactants such as polyoxyethylene secondary alcohol ethers may be used in the present invention. The concentration of the nonionic surfactant in the solvent composition of the present invention may be about 0.5 weight percent, or about 0.5 weight percent to less than 1 weight percent.

The solvent composition of the present invention is suitable for use in removing at least one of water or water soluble contaminants from an article using a cold cleaning process. The article is contacted with the solvent of the present invention to remove contaminating residues. Immersing the article in a solvent of the invention or spraying a jet of a solvent of the invention onto the article.

The methods presented herein can be used to clean a wide variety of articles. Non-limiting examples of articles include metal products, glass products, plastics, polymer substrates, electronic components or articles, and combinations thereof.

In the method of the present invention, cleaning may be achieved by contacting the article in a bath containing the solvent composition. The article may optionally be subjected to ultrasonic agitation, or contacted with a jet of the solvent composition. In another aspect, the solvent composition is sprayed on the article prior to degreasing.

The method of the present invention is suitable, for example, for removing at least one of water or water-soluble contaminants from the article in cold cleaning applications. Cold cleaning of articles is typically carried out at ambient temperature, e.g. at up to about 55 ℃. Cold cleaning is generally characterized by immersing and soaking the item to be cleaned in the solvent composition with or without agitation. Items that are too large to be dipped may be sprayed with the solvent composition. Ultrasonic waves may be used in conjunction with cold cleaning to remove at least one of water or water-soluble contaminants from deep recesses or other inaccessible areas.

In another aspect, the method of the present invention is suitable for use in hot washing for drying. Ultrasound may optionally be used in conjunction with a hot rinse to remove at least one of water or water soluble contaminants from deep recesses or other inaccessible areas.

In another aspect, a flusher for hot flush applications is provided with a set of cooling coils near the top thereof. The cooling coils are in contact with the solvent vapor before it escapes the unit, which causes the vapor to cool and condense. The vapor condensate flows back to the clean tank where the solvent is present. At least one of the water or water-soluble contaminants is separated by using various separation methods including, but not limited to, membrane separation and/or gravity separation.

The process of the present invention provides several advantages over existing processes and these advantages will be described in more detail by specific examples. The following examples are provided for illustrative purposes and are not intended to limit the invention in any way.

One of the advantages of the present invention is that the solvent composition used in the process of the present invention does not form an emulsion even in the presence of excess water, which allows the process of the present invention to provide for the removal of at least one of water or water soluble contaminants, and at the same time, good separation between the aqueous phase and the solvent phase.

Another advantage is that the solvent composition of the present invention can easily and quickly remove water or water-soluble contaminants from an article without undergoing rapid decomposition in the presence of water.

Examples

The following examples are illustrative of the principles of the present invention. It should be understood that this invention is not limited to any one particular embodiment exemplified herein, whether in the examples or elsewhere in this patent application.

Example 1

Experiments were conducted at room temperature to assess the rinsability of the solvent compositions of the present invention. The solvent composition of the present invention is prepared by combining n-propyl bromide in weight percent shown in table 1 with an alcohol to form a first composition, and then by adding a surfactant in weight percent shown in table 1 to the first composition. In these experiments, newly prepared glass beads having a diameter of 2mm were put into a 25ml measuring cylinder, and 2ml of water was added to the glass beads. Each of the solvents of the present invention shown in table 1 was then added to a measuring cylinder containing glass beads and water. The volume of the aqueous phase was measured after 5 minutes. A volume of the aqueous phase of 0.5ml or more is considered a positive test for the flushing capacity, while a larger volume indicates a better flushing capacity. The results of this test are summarized in table 2.

Example 2

An experiment was performed at room temperature as in example 1 in order to evaluate the separation ability of the solvent of the present invention. In these experiments, 10ml of each solvent shown in table 1 was injected into a 100ml glass bottle. 2ml of water was added to the solvent, and then the bottle was capped and shaken to mix the solvent with the water. No emulsion was considered a positive test for separation ability. The results of this test are also summarized in table 2.

TABLE 1

TABLE 2

¹Is = no emulsion formation

Example 3

The decomposition rate of a mixture of 90 weight percent n-propyl bromide and 10 weight percent n-propanol was measured by determining the consumption rate of 1, 2-butylene oxide. 1, 2-butylene oxide was added to a mixture of n-propyl bromide and n-propanol to reach a final concentration of 0.5 weight percent and was injected into two 100ml sample vials in equal volumes. 2g and 0.1g of water were injected into each sample bottle. The sample was kept at 35 ℃. An aliquot was taken out of the sample bottle and analyzed for the consumption of 1, 2-epoxybutane by gas chromatography. The results are presented in table 3.

TABLE 3

While the invention has been described in terms of one or more embodiments, it will be appreciated that other modifications may be made without departing from the scope of the invention, which is set forth in the claims below.

Claims (19)

1. A solvent composition, comprising:

a. about 50 weight percent to about 99 weight percent n-propyl bromide;

b. about 0.5 weight percent to about 50 weight percent alcohol; and

c. at least 0.005 weight percent surfactant.

2. The solvent composition of claim 1 wherein the concentration of n-propyl bromide is about 80 weight percent to about 98 weight percent.

3. The solvent composition of claim 1 wherein the concentration of n-propyl bromide is about 88 weight percent to about 95 weight percent.

4. The solvent composition of claim 1 wherein the alcohol is an aliphatic monohydric alcohol.

5. The solvent composition of claim 4, wherein the alcohol comprises 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-heptanol, or 1-hexanol and pentanol.

6. The solvent composition of claim 1, wherein the surfactant comprises a non-ionic surfactant, or a product of a reaction between a fatty acid reactant and an amine reactant.

7. The solvent composition of claim 6, wherein the non-ionic surfactant comprises a polyoxyethylene alkyl ether, a polyoxyethylene secondary alcohol ether, or a polyoxyethylene alkylphenyl ether.

8. The solvent composition of claim 6 wherein the non-ionic surfactant is biodegradable.

9. The solvent composition of claim 7, wherein the fatty acid reactant comprises a fatty acid containing C₆To C₁₂An aliphatic monocarboxylic acid of (2).

10. The solvent composition of claim 7, wherein the amine reactant comprises a compound comprising C₆To C₁₂The aliphatic monoamine of (1).

11. A method of cleaning an article, the method comprising contacting the article with a solvent composition for removing at least one of water or water-soluble contaminants, wherein the solvent composition comprises from about 50 weight percent to about 99 weight percent n-propyl bromide, from about 0.5 weight percent to about 50 weight percent alcohol, and at least about 0.005 weight percent surfactant.

12. A method of removing at least one of water or water-soluble contaminants from an article, the method comprising:

a) contacting the article in a bath filled with a solvent comprising:

i. about 50 weight percent to about 99 weight percent n-propyl bromide;

from about 0.5 weight percent to about 50 weight percent alcohol; and

at least 0.005 weight percent surfactant;

b) introducing a mixture comprising the solvent and water or water-soluble contaminants into a tank for separation; and

c) returning the separated solvent to the pool.

13. The method of claim 11 or 12, wherein the alcohol is an aliphatic monohydric alcohol comprising 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-heptanol, or 1-hexanol and pentanol.

14. A process as set forth in claim 11 or 12 wherein the surfactant comprises a nonionic surfactant or a product of a reaction between a fatty acid reactant and an amine reactant.

15. The method of claim 14, wherein the non-ionic surfactant comprises a polyoxyethylene alkyl ether, a polyoxyethylene secondary alcohol ether, or a polyoxyethylene alkylphenyl ether.

16. The method of claim 14, wherein the fatty acid reactant comprises a fatty acid containing C₆To C₁₂An aliphatic monocarboxylic acid of (2).

17. A process as set forth in claim 14 wherein said amine reactant comprises a compound comprising C₆To C₁₂Including mixtures thereof.

18. The method of claim 11 or 12, wherein the article comprises a metal product, a glass product, a plastic, a polymer substrate, or an electronic component or article.

19. The method of claim 11 or 12, wherein the method comprises cold cleaning or hot rinsing.