NON-AQUEOUS SILOXANE SOLVENT COMPOSITIONS

Abstract

This invention relates to non aqueous non-volatile alkylated siloxane compositions having low VOC and vapor pressure of about 31 millimeters of mercury at 20° C. consisting essentially of a mixture of a linear or open-chain methyl alkylated siloxane having two silicon atoms and a siloxane having three silicon atoms alkylated with methyl groups.

Claims

1. Siloxane compositions having low VOC and a vapor pressure of about 31 millimeters of mercury at 20° C. consist essentially of from about 55 to 75 parts by weight of an alkylated open-chain siloxane having two silicon atoms and from about 25 to 45 parts by weight of an alkylated open-chain siloxane having three silicon atoms.

2. The siloxane composition of claim 1 wherein the alkylated open-chain siloxane having two silicon atoms is hexarnethyldisiloxane and the alkylated open-chain siloxane having three silicon atoms is octamethyltrisiloxane.

3. The siloxane composition of claim 2 wherein the hexamethyldisiloxane is present in the siloxane composition in an amount ranging from about 60 to 70 parts by weight and the octamethyltrisiloxane is present in the composition in an amount ranging from about 30 to 40 parts by weight.

4. A siloxane composition for cleaning metal having a low VOC and a vapor pressure of about 31 millimeters of mercury at 20° C. consisting essentially of from about 62 to 65 parts by weight of hexamethyldisiloxane and from about 35 to 38 parts by weight of octamethyltrisiloxane.

5. The siloxane composition of claim 4 wherein the hexamethyldisiloxane is present in the composition in an amount of about 63 parts by weight and the octamethyltrisiloxane is present in the composition in an amount of about 37 parts by weight.

6. A process for removing and cleaning oleaginous materials from a metal surface which comprises adding an effective amount of a siloxane composition onto said oleaginous-containing metal surface and subsequently cleaning the oleaginous material from the metal surface: said siloxane composition having a low VOC and a vapor pressure of about 31 millimeters of mercury at about 20° C. and consist essentially of from about 55 to 75 parts by weight of an alkylated open-chain siloxane having two silicon atoms and from about 25 to 45 parts by weight of an alkylated open-chain siloxane having three silicon atoms.

7. The process of claim 6 wherein the siloxane having two silicon atoms is hexamethyldisiloxane and the siloxane having three atoms is octamethyltrisiloxane.

8. The process of claim 7 wherein the hexamethyldisiloxane is present in the siloxane composition in an amount ranging from about 60 to 70 parts by weight and the octamethyltrisiloxane is present in the siloxane composition in an amount ranging from about 30 to 40 parts by weight.

9. The process of claim 7 wherein the hexamethyldisiloxane is present in the siloxane composition in the amount of about 63 parts by weight and the octamethyltrisiloxane is present in the siloxane composition in the amount of about 37 parts by weight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a bar graph which shows selected commercial solvent products.

[0013] Compositions of the linear or open-chain siloxanes of this invention (Wipe Solvent Formulations) are as follows:

TABLE-US-00001 EXAMPLE 1 Parts By Weight Hexamethyldisiloxane 55 to 75 Octamethyltrisiloxane 25 to 45

TABLE-US-00002 EXAMPLE 2 Hexamethyldisiloxane 60 to 70 Octamethyltrisiloxane 30 to 40

TABLE-US-00003 Example 3 Hexamethyldisiloxane 62 to 65 Octamethyltrisiloxane 35 to 38

TABLE-US-00004 Example 4 Hexamethyldisiloxane 63 (63%) Octamethyltrisiloxane 37 (37%)

Properties of the NAVWIPE (Wipe Solvent Formulation)

[0014] Several commercial exempt solvents were selected for testing and evaluation for wipe cleaning applications in accordance with the requiremnets of MIL-PRF-32295A Type III (Table 1). Drying times after cleaning with solvents play an important role in industrial cleaning applications. The drying process depends on several factors such as the vapor pressure of the cleaning solvent, temperature, humidity, and the velocity of the airflow. The Aerospace National Emission Standards for Hazardous Air pollutants (NESHAP) (40 CFR 63 Subpart GG) limits the vapor pressure values for wipe cleaning applications to equal or less than 45 mmHg at 20° C. The vapor pressure of this invention (Navwipe) was determined to be about 31 mmHg at 20° C. as shown in Table 1. Few of the selected commercial products have met NESHAP's vapor pressure requirements for wipe-cleaning applications.

TABLE-US-00005 TABLE 1 Comparison of Navwipe with Selected Commercial Solvent Products for Wipe-Cleaning Applications Vapor Pressure Manufacturer Product VOC mmHg at 20° C. DuPont Vertrel XF Exempt 226 Garrett High Sol-X Exempt NA Services, Inc. PPG Esol-146 Exempt NA aerospace PRC-DeSoto Micro Care Silicon Carrier Fluid Exempt 226 Sigma-Aldrich Acetone Exempt 184 Lyondell Ter-Butyl Acetate Exempt 42 NAVAIR (Navwipe) Exempt 31 Invention AGC Ashiklin AE 3000 Exempt 233 Chemicals America AGC Ashiklin AE 3100E Exempt 210 Chemicals America Kowa Dimethyl Carbonate Exempt 55 American Corp.

Effect on Plastics (Crazing Test)

[0015] The effect of the siloxane composition and selected commercial products on plastics was studied in accordance with ASTM F 484. The plastic materials used for this test are listed below: [0016] a. MIL-PRF-5425 cast acrylic (annealed in accordance with ASTM F 484) [0017] b. MIL-PRF-25690 stretch acrylic [0018] c. SAE AMS-P-83310 polycarbonate

[0019] The specimens were secured in the loading fixture. The product was applied onto the top surface of the plastic by spraying back and forth three times in ten seconds from a distance of six inches. The test coupons were allowed to air dry for one hour and then were examined for crazing and strength loss. Crazing is evident when a flashlight is used to illuminate the specimen from a direction tangent to the specimen bend. Strength loss is evident if, when removed from the fixture, it fails easily when bent by hand. The results of the crazing test for the selected commercial products and the new invention on the cast acrylic plastic are shown in Table 2. All tested products failed the crazing test with the exception of the siloxane composition of this invention, (Navwipe) which met the requirement. In addition, the siloxane composition (Navwipe) passed the test requirements of stretch acrylic and polycarbonate materials.

TABLE-US-00006 TABLE 2 Compatibility of Selected Commercial Products on Plastics (Crazing Test: ASTM F 484) Cast Acrylic Product MIL-PRF-5425 High Sol-X Fail Esol 146 Fail Dimethyl Carbonate Fail Acetone Fail Ashiklin 3100E Fail Ashiklin 3000 Fail Ter-Butyl Acetate Fail Navwipe PASS

[0020] The cleaning efficiency test for Navwipe cleaner was conducted in accordance with test method 4.5.9 in MIL-PRF-32295A Type III as described below.

[0021] Preparation of test specimens: Stainless steel coupons of 1 by 2 by 0.05 inches (25 by 50 by 1.3 mm) were polished with 240-grit aluminum oxide abrasive paper or cloth and solvent wiped with isopropyl alcohol. Coupons were weighed (weight=W1), coated on one side with 20-25 mg of soil, then reweighed (weight=W2). Soils used for testing were the following:

[0022] a. MIL-G-21164 (Grease, Molybdenum Disulfide, for Low and High Temperatures)

[0023] b. MIL-PRF-83282 (Hydraulic Fluid, Fire Resistant, Synthetic Hydrocarbon Base)

[0024] c. MIL-PRF-10924 (Grease, Automotive and Artillery)

[0025] Test Procedure.

[0026] Fresh solvent was used for each soil tested. Each test coupon was cyclically immersed and withdrawn from a 150-ml beaker containing 100 ml of the cleaner at a rate of 20 cycles per minute for 5 minutes. Each coupon dried for 10 minutes at 140±4° F. (60±2° C.), cooled to room temperature, and reweighed (weight=W3). Cleaning efficiency for the cleaner was calculated as follows for each coupon:

% Cleaning Efficiency=(W2−W3)/(W2−W1)×100

[0027] The cleaning efficiency of the siloxane composition (Navwipe) was conducted in accordance with the requirements of MIL-PRF-32295A Type III and the results are shown in Table 3. In addition, the results of cleaning efficiency of the selected products on one soil (MIL-G-21164) are shown in Table 4. As shown in FIG. 1, the results indicate that the siloxane compositions of this invention (Navwipe) is the only product that meets the requirements of MIL-PRF-32295A Type III.

TABLE-US-00007 TABLE 3 Cleaning Efficiency Test Results for a. Siloxane Composition (Navwipe) Product MIL-PRF-32295A Type III New Invention Soil Requirements (Navwipe) MIL-G-21164 70% 71% MIL-PRF-10924 85% 96% MIL-PRF-83282 95% 97%

TABLE-US-00008 TABLE 4 Cleaning Efficiency Test Results for the Selected Commercial Products in Accordance with MIL- PRF-32295A Type III (MIL-G-21164 Soil) Cleaning Efficiency Percentage (%) Product (MIL-G-21164 Soil) Vertrel-XF 62.1 High Sol-X 67.0 Esol 146 68.8 Silicon Carrier Fluid 67.0 LHB 66.95 Methyl Acetate 66.97 Dimethyl Carbonate 64.70 Ashiklin AE-3100E 65.40 Ashiklin AE-3000 60.40 Solkane 365 mfc 63.95 Acetone 64.80 Siloxanes (Navwipe) 71.00

[0028] The specific siloxanes of this invention consist essentially of linear or open-chain alternating silicon and oxygen atoms wherein the prefix denotes the number of silicon atoms alkylated with methyl groups. It was found that the di and trisiloxane mixtures alkylated with alkyl methyl groups (Navwipe) were the only products that met the requirements of MIL-PRF-32295A Type III as shown by the data in Table 3 and FIG. 1.

[0029] The benefits of the siloxane compositions of this invention are providing the fleet with effective, safe, environmentally-friendly wipe-solvent cleaner. Providing qualified cleaners to all levels of maintenance will avoid risk of use of improper materials, which may compromise performance, safety and health. In addition, the outcomes of this invention are improving the fleet readiness, and pollution prevention onboard ships and complying with the current environmental regulations. To meet the new environmental regulations, it is essential to identify and validate effective, safe, and environmentally friendly products for cleaning applications. The Navwipe will be used to clean weapon systems across Department of Defense (DOD) maintenance facilities as alternatives to the current high VOC products. The advantages of the Navwipe cleaner include: [0030] Exempt Solvent, [0031] Odorless properties, [0032] Free of HAPs, [0033] Compatible with metals and non-metals, [0034] Non-toxic, [0035] Dry fast, [0036] Contains no ozone-depleting substances (ODSs), [0037] Cleaning efficiency is equivalent to the high VOC control, [0038] Complies with EPA and the new environmental regulations, [0039] A new alternative for high VOC commercial products, and [0040] Provides a safer and environmentally friendly cleaner to the fleet.

[0041] The siloxane composition (Navwipe) will be used for cleaning aircraft structure (metal and composite) surfaces prior to painting, sealing, bonding, application of adhesion promoters. In addition, the Navwipe will be used as a replacement for hazardous chemicals currently used by the fleet such as methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK), and MIL-T-81772 for wipe-cleaning applications.

[0042] While various embodiments of the invention have been disclosed, the specific composition and methods described herein are not intended to limit the scope of the invention.