Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors

Definitions

• the present invention relates to the prevention of corrosion of metals by solutions of organic acid esters of cellulose in halogen-containing organic solvents. More particularly, it relates to novel processes for preventing such corrosion by incorporation in the solution of special stabilizing agents.
• these esters may be dissolved in halogen-containing organic solvents.
• cellulose triacetate is dissolved in methylene chloride which may also contain minor amounts of co-solvents for the ester such as methanol, ethanol, isopropanol or the like, as well as small amounts of water.
• This solution or dope is then dry spun into filamentary cellulose triacetate, the solvent being evaporated by a current of warm air followed by recovery and purification prior to re-use.
• the spinning is effected by passage of the solution through one or more orifices in a metallic member in the art referred to as a jet. It has been found that these jets as well as other metal equipment contacted by the solvent during use and recovery c rrode rapidly and require frequent replacement.
• Another object is to provide a solution of cellulose triacetate in methylene chloride, which solution can be dry spun without rapid corrosion of the spinning jet.
• a stabilizer which inhibits corrosion of metallic members.
• the stabilizers must satisfy certain requirements in order to be suitable for. use, viz., they must themselves be non-corrosive, they.
• the solvent. of the cellulose ester solution can be any Patented Mar. 1, 1960 systems, e.g., organometal salts or acid binding agents such as triethylamine and triethanolamine, are ineffective 'in'the instant situation. Moreover, the corrosion of the spinning jets is apparently independent of temperature,
• the stabilizers will exert some beneficial action even in the smallest amountsbut for appreciable inhibition they should be present in at least about 0.005% by weight ofthe solution. Generally, at least about 0.01% by weight is employed and preferably about 0.05%. As much as 0.5% or even more can be used but since corrosion is substantially completely eliminated with lesser :amounts there is no point in adding more stabilizer than is neceshalogenated organic solvent but the preferred solvents are chloLne-substituted lower alkanes such as methylene chloride, ethylene dichloride, and the like. contain minor amounts of co-solvents or non-solvents for the esters, depending upon the properties desired for the composition and the subsequent treatments to which it will be subjected. When a methylene chloride solution is to be used for'dry-spinning, for example, the methylene chloride solvent may contain as much as 20% 'by weight stabilizing action will be realized even in the presence of water.
• Organic acid esters of cellulose which can be' used are preferably the lower alkanoic acid esters such as the acetate, propionate, butyrate, acetate-propionate, acetatebuty rate, and the like. While the invention is applicable to any esters which will dissolve in the indicated solvents,
• esters are substantially fully acetylated, i.e., free of unreacted hydroxy groups, and are hereinafter referred to as cellulose triacetate although a small residue of unreacted hydroxy-groups may be present.
• the present invention is particularly useful in the dry spinning of solutions of cellulose triacetate in methylene chloride-methanol, such as are disclosed in copending US. application Serial No. 566,088,..filed February 17, 1956, by Robert K. Davies and'Arnold J. Rosenthal.
• the solutions there described comprisecellulose acetates having an acetyl value in excess of 59.5% by weight expressed as acetic acid (herein referred to as cellulose triacetate) dissolved in methylene chloride-methanol to These may a concentration of above 15% and preferably from 17 to 27%.
• the methylene chloride can range upwards from 80% of the combined weights of methylene chloride and methanol 'with about 90% or more preferred.
• These solutions generally contain small amounts of water, from about 0.3% of the weight of the solution up to the amount which will create turbidity, although preferably water is present in no more than 60% by weight of the amount which will create turbidity. The amount of water which will create turbidity will vary with the composition of the solution. With the minimum concentration of 15% by weight of cellulose triacetate in the solution and about of methanolin the solvent the turbidity point will correspond to about 1.7% of water.
• the amount of stabilizer adhered to the cellulose triacetate is extremely small and any small residual amounts will be removed during the wet treatments to which fabrics made from said filamentary materials are normally subjected.
• EXAMPLE II To compare quantitatively the corrosive action of dopes of different composition, strips of hot rolled mild steel measuring inch by /s inch by 2% inches are immersed in the dopes for 14 days at 50 C. without agitation and the extent of corrosion of the strips is determined. The dopes in this comparison all are initially 15% by weight solutions of cellulose acetate (61.5% acetyl value) in a 91/9 weight mixture of methylene chloride/methanol. Where water or inhibitor is indicated, the percentage is based on the total weight of the dope. The results are shown in the following table:
• the dopes containing the Z-hydroxypropylamine nitrite and the cadmium 2-ethyl hexoate are suitable for spinning and solvent recovery with little or no corrosion of metal equipment contacted therewith.
• a stable composition of matter, non-corrosive on metals contacted therewith comprising a solution in a 4 halogen-containing organic solvent of a lower alkanoic acid ester of cellulose and a stabilizing proportion of a member selected from the group consisting of a hydroxy lower alkyl amine nitrite and a cadmium salt of a waterinsoluble fatty acid.
• composition ofmatter according to claim 1 wherein said solvent contains up to about 20% by weight of a lower alkanol
• a stable composition of matter, non-corrosive on iron contacted therewith comprising a solution in a chlorine-containing organic solvent of a lower alkanoic ester of cellulose, said solution containing at least about 0.005% by weight of a hydroxy lower alkyl amine nitrite as a stabilizer.
• a stable composition ,of matter, non-corrosive on iron contacted therewith comprising a solution of cellulose triacetate in methylene chloride, said solution containing about 0.005 to 0.5% by weight of a hydroxy lower alkyl amine nitrite as a stabilizer.
• a stable composition of matter, non-corrosive on iron contacted therewith comprising a solution of cellulose triacetate in a concentration of at least 15% by weight in a solvent comprising methylene chloride and a lower alkanol, the methylene chlorideconstituting at least about by weight of thesolvent, said solution containing about 0.005 to 0.5 by weight of Z-hydroxypropylamine nitrite as a stabilizer.
• a stable composition of matter, non-corrosive on iron contacted therewith comprising a solution of cellulose triacetate in a concentration ranging from about 17 to 27% by weight in a solvent comprising about by weight of methylene chloride and about 10% by weight of methanol, said solution containing water in an amount between a minimum of about 0.3% by weight and a maximum of the amount which will bring the solution to the turbidity point, said solution further containing about 0.005 to 0.5% by weight of 2-hydroxypropylamine nitrite as a stabilizer.
• a stable composition of matter, non-corrosive on metals contacted therewith comprising a solution of cellulose triacetate in methylene-chloride, said solution containing a stabilizing proportion of 2-hydroxypropy1 amine nitrite.
• a stable composition of matter, non-corrosive on iron contacted therewith comprising a solution in a chlorine-containing organic solvent of a lower alkanoic ester of cellulose, said solution containing at least about 0.005% by weight of a cadmium salt of a water-insoluble fatty acid as a stabilizer.
• a stable composition of matter, non-corrosive on iron contacted therewith comprising a solution of cellulose triacetate in methylene chloride, said solution containing about 0.005 to 0.5% by weight of a cadmium salt of a water-insoluble alkanoic acid as a stabilizer.
• a stable composition of matter, non-corrosive on iron contacted therewith comprising a solution of cellulose triacetate in a concentration of at least 15% by weight in a solvent comprising methylene chloride and a lower alkanol, the methylene chloride constituting at least about 80% by weight of the solvent, said solution containing about 0.005 to 0.5% by weight of cadmium 2-ethyl hexoate as a stabilizer.
• a stable composition of matter, non-corrosive on iron contacted therewith comprising a solution of cellulose triacetate in a concentration ranging from about 17 to 27% by weight in a solvent comprising about 90% by weight of methylene chloride and about by weight of methanol, said solution containing water in an amount between a minimum of about 0.3% by Weight and a maximum of the amount which will bring the solution to the turbidity point, said solution further containing about 0.005 to 0.5% by weight of cadmium 2-ethyl hexoate as a stabilizer.
• a stable composition of matter, non-corrosive on metals contacted therewith comprising a solution of cellulose triacetate in methylene chloride, said solution containing a stabilizing proportion of cadmium 2-ethy1 hexoate.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Artificial Filaments (AREA)

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Cited By (3)

Citations (4)

• 0
  • BE BE634681D patent/BE634681A/xx unknown
• 1957
  • 1957-05-31 US US662602A patent/US2927031A/en not_active Expired - Lifetime

Patent Citations (4)

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