US2739128A

US2739128A -

Info

Publication number: US2739128A
Authority: US
Priority date: 1951-03-23
Publication date: 1956-03-20
Anticipated expiration: 1973-03-20
Also published as: CH300096A; BE510135A

Description

purposes.

2,7s9,12s= FIiLM FORMLQECoii IPESTTENS Nicholas M'." A'd'am's; Chicago; 111.. Nb Drawing; rip i aaaliimiitn '23, 1951', set-isms. 217,305 5 Claims; c1; 252 -495 The invention'is"concernedwith film-forming compositioris, and m'or'eparticularly itrelatesto the-forming'of films on. metal surfaces, which films have'a protective action and are excellently adapted for use'in metalcori figurating operations.

In cold drawing; forrning*an'd other cold shaping. operations on'metal bodies such as sheet, plat'e,.rod'. and wire, it is important that the operation beso' conducted that no scoring or tearing of .the' metal occurs under the high pressures employed.- In conventional practiceboth' the worlrpieceand the tools'such as' dies orrolls are. coated with some film-forming composition or'lubric'ant' throughout the configurating' operation. Many types'i'of film-' forming compositions and lubricants are employed in industry for this purpose? Long experience has shown, however, that a givencomposition, while excellent with certain operations and metals, often is wholly. unsuitable when the Work' conditions or nreta'l'ischan'ged. Although no universally. satisfactory composition hasbeenr' found for general use" in cold forming operations; there are certain w'e'll known characteristics which such a. com'posh t'ionslio'uldhave. Theiutility" of the composition of: the present inventionv caii be evaluated-in part by'th'e extent to which itfisshown to possess these characteristics.

For maximumiover=all"utilify the film-formingcom position should greatly reduce the friCtiQn'be'tWeen-the' ice , to provide film-compositions of highlytenacious adhere ence to surfaces," andof other exceptional qualtities.

These films can beapplied-uniformly to -metal or other.

surfaces through-themediumiof a suitable solvent forthe two components, or by means'of an emulsion in another carrier material. A solventof low temperature.volatility, is preferable; Whereformationof a fast-dryingfilm is. desired, but for some purposes a solvent. of slower evaporationrate may be more suitable.

Thepolymericsilicones or polyorganosiloxanes are,

ordinarily prepared in a partiallypolymerized formby.

thehydrolysis of organosilanes which contain .at least two hydrolyzable substituentson their silicon atoms, such as hydrogen, halogens and alkoxy radicals, the. remainingvalances of thesilicon atoms being satisfied by organic radicals joined to the siliconthrough carbon atoms. The intermediate products ,of hydrolysis. are. organosilanols, with hydroxy groups directly attached to the silicon, and these condense immediately, or very readily; toform the partially polymerized silicones with the characteristic SiO Sibond structure.

,Amonga great many polysiloxane derivatives which may be operative for the purpose of this invention, my investigations to date indicate a preferred action in. alkyl: polysiloxanes. as derived from hydrolysis of the corresponding alkyl halogenosilanes or mixtures of thesewith alkoxysilanes. For example, a composition made by hydrolyzing and condensing a mixture of amyl trichlorosila'ne and triethoxysilane, in relative proportions respectively of about 5 to vlparts by-Weighn'has given excellent results for thepurpose intended. This. polysiloxane was condensed: to the'point of forming a viscous liquid, of a chemical structure containing certain Si+H- bonds, as

well as similarly bondedalkyl groups, the former bondfrom ethyl dichlorosilane as the sole starterjmateriah This sliding surfaces of the workpiece and the tool. "This:

property is dependent. not alone on the lubricating properties of the composition under the prevailing conditions; but also upon the filth strength as well. The. film'strengt'h must be sufficient to avoid mechanical breakdown under the high pressures employed; and to maintain the desired properties under the rise in temperature on the surfaces of thesliding metal members during the coiifigurating operation. I

Aside from these essential requisites, there are other propertieswhich are desirablein'film-forming compositior'is of this nature. Among these are the easeiofits application to, and removal from, the workpiece and tool, its spreading power and its adhesiveness to metal surfaces. Also the composition should be "stable-and .maintainaits useful properties without deterioration from chemical other uniquepropertieswhich render them particularly suitable for use in cold forming operations, and for other l The nvention lies iinarilygin e han that certain 'silioones exert a eoepeisevq efiectin combination with particular materials "of extremepres'sure"characteristics,

be described later. Of ma'ny solvents tested my: present product was completely hydroyzed, and partially con densed, so that the final composition was essentially a mixture of the groupings [(C2H5)HSiO]n and The presence of Si-H bonds is also evident in this polysiloxane, and there is some evidence that this internal structure in the polymer molecule may in part account for theetfectiveness in the invention of both materials as described.

The second important component of the new composition comprises a material, as already indicated which has been known and used in extreme pressure lubrication, usually as an additive to mineral oils. Among a great many of such compounds now available, halogenated aliphatic materials, such as the chlorinated parafiin waxes and fatty acid derivatives have proven especially useful. Preferably the extreme pressure component should be one which may tend to decompose at the metal temperaturesencountered in deep drawing, such temperatures often being in the neighborhood of 250 C. to 300 C 'Paraffin waxes chlorinated to an extent of 30% to 40% by weight have been used successfully in'many formulations.

jThe solvent oremulsifyingingredient of the completely 'hliei'idedjnixturefseryes essentiallyas' a carrier to enable ready application of a' thin, and uniform, layer of the essential film components tothe metal surface. Many known solvents may be useful in this capacity, provided they are compatible with the other ingredients, and produce a homogeneous liquid solution. A volatile solvent is desirable for a rapid dry film application, and a compound solvent to greases and oils has advantages, as will preference is'for compou'ndslike trichloroethylene,'petro- Mar 29,..-

leum ether, or mineral spirits of about 105 F. flash point.

With regard to the relative proportions in the final filmforming composition, this too can be varied considerably, but in general about one part by weight of the polysiloxane to three or four parts or more of the chlorinated aliphatic compound will produce the desired effect, this mixture in turn being incorporated in the solvent in a total weight amount of from about 5% to A more specific satisfactory formula has consisted of grams of the previously-described copolymer of amyl trichlorosilane and triethoxysilane, 70 grams of a 40% chlorinated paraffin wax, and 1000 cc. (1455 grams) of trichloroethylene. Substitution for the polysiloxane of the product made directly from ethyl dichlorosilane, in the same relative proportion, also has provided a very effective filmforming composition. Additives of various sort, for in hibitory or other purposes, may be incorporated in the formulae described, and in working with wet films, an oil, like hydrogenated castor oil, or fatty acids and their derivatives, may be added in small amounts to improve slippage.

As previously indicated, a most valuable present-known use for the films of the invention is in metal forming operations which now will be described more in detail.

The blended composition, as it will normally be used,

may readily be applied to metal members, as by wiping it on the work piece just prior to the forming operation. Due to the fast evaporation of the solvent, the film is formed in a matter of seconds and there is no objectionable delay between application of the composition and the subsequent shaping operation. If desired, and for many operations it may be preferred, the film may be applied long prior to the shaping operation, and because of its high tenacity and adhesiveness it will remain unimpaired for extended periods. The pro-applied film will also serve to protect the surface of the metal and keep it in such condition that the shaping operation may be performed without additional treatment. In large scale operations, the metal to be shaped may be advantageously coated with the film-forming compositionof the invention at the sheet rolling mill, and subsequently used by the cold forming plant as received from the mill, without further treatment. Due to the oil dissolving properties of the solvent component of the composition, the coating of metal sheet at the mill is greatly facilitated. Oil coated sheets as normally prepared at the mill need only be dipped or continuously passed through a bath of the film-forming composition, in which step the oil on the surface of the sheets is dissolved and combined with a coating of the film-forming composition. Upon evaporation of the solvent, an almost instantaneous occurrence, a lasting film forms on the surface of the metal sheet, which film protects the sheet so effectively that e en after prolonged storage the sheet is in an entirely satisfactory condition for cold shaping operations without further treatment or lubrication.

The new film composition is economical to use because of its excellent spreading properties. In many tests it has been found that surface areas of 550 square feet and larger may be satisfactorily coated with a single pound of the composition. Due to the extreme thinness of the applied film. subsequent cleaning of the sheet after the shaping operation is unnecessary and often undesirable. This factor improves housekeeping and effects further economies in the use of the composition. However, since thefilm is a non-conductor of electricity it may be desirable in some operations, as for example electroplating, to remove the film. This may be done by any Well-known dissolving process, as, for example, by dissolving the film in a bath of the solvent in the film-forming composition of the invention.

The film has been employed in comparative cold shaping tests with standard procedures in full scale commercial operations. In all of these tests the composition of the invention has been found to be entirely satisfactory, and equal, or superior, in performance to the materials heretofore employed. In those instances wherein the customary procedure, due to long experience, was satisfactory from the cold shaping aspects of the problem, the composition of the invention was also equally satisfactory, and in addition was easier in its method of application, as well as more desirable and economical, in that no cleaning operation was required subsequent to the cold forming operation.

Under the particularly severe conditions of cold drawing operations an important property of the film-forming material lies in its ability to prevent firing of the die. Firing of the die occurs when a small flake of metal Welds itself to the die. On each successive draw the welded flake scores the work piece and becomes larger, thus necessitating a shutdown to clean the die. Another property of considerable importance in the cold drawing of metals is the degree of hold back exhibited by the film-forming compound or lubricant employed. The effect of hold back can be readily shown by employing the film on a work piece or blank whereon a flange is obtained in the drawing operation. The greater the degree of hold back exhibited by the film the larger the flange will be. Excessive hold back will cause the blank to fracture. In practically all but easy drawing operations on light'sheet there is a pressure pad associated with the die, which clamps the outer edge of the blank to the die prior to the punch contacting the blank. The purpose of the pad is to prevent wrinkling of the edges of the blank. However, by varying the pressure on the pad the width of the flange formed in the operation may be varied. Accordingly, the hold back of the film must be within the range which can be controlled by adjustment of the pressure pad.

The film of the invention was employed in comparative tests on a commercial scale on the cold drawing of stainless steel coffee pots, wherein dry soap was the conventional lubricant. In the first three tests the polysiloxane component of the composition was a copolymer of mol per cent amyl trichlorosilane and 20 mol per cent triethoxysilane. In the fourth tests the polysiloxane employed was an ethyl dichlorosilane polymer. In all four tests the extreme pressure additive was a chlorinated paraflin wax containing about 40% chlorine and the solvent was trichloroethylene. The ratio of the silicone to the extreme pressure component was 1 to 2 in test No. l; l to 5 in test No. 2; l to 15 in test No. 3; and l to 5 in test No. 4. After evaporation of the solvent the film formed in all tests had excellent anchorage to the metal surface. Upon heating test strips of the metal the film held firm to the metal in tests Nos. 1 and 2 but had a tendency to run off the metal in tests Nos. 3 and 4. The wetting and tenacity of the film was satisfactory in all tests but was exceptionally high in tests Nos. 1 and 2. Under standard operating conditions the drawing characteristics of the film-coated metal in each of the four tests was excellent. In none of the tests was there any galling or seizure and the surface finish on the completed articles was bright and unmarred. The soap used in the prior standard practice is soluble in water and somewhat hygroscopic, whereas the film of the invention is not. For this reason the steel coated with soap had to be drawn soon after its application, but blanks coated with the film of the invention, for periods of up to four months and longer, have been drawn satisfactorily. In addition the soap used in the prior practice had to be washed off subsequent to the drawing operation. This step is entirely eliminated with the metal coated with the film of the invention.

In many cold forming operations it is necessary to anneal the metal blank between successive working stages. With some materials used in the prior art such as oil and soap this intermediate annealing operation results in carbonizing and staining the metal unless a cleaning tions, it has been found that sheet coated with the composition of the invention exhibits superior cold rolling characteristics over sheet not so treated. In a specific application 0.097 inch thick hot rolled carbon steel was coated with the composition of the invention and cold rolled to a thickness of 0.010 inch in seven passes through the rolls. Normally ten to twelve passes have been required in standard practice. In addition the film coated sheet had a cleaner and brighter surface than sheet rolled by the standard practice.

The examples herein given of the methods of employing the film-forming composition of the invention are intended as illustrative examples only and not intended in any manner to limit the scope of the invention as defined in the appended claims.

What is claimed is:

l. A composition adapted to form strongly adherent films on metal surfaces comprising a polyorganosiloxane having alkyl substituents and hydrogen bonded to the silicon atoms, a chlorinated paraifin wax of extreme pressure lubrication characteristics, and a readily volatile solvent carrier for the aforesaid components, the first two components being in relative proportions respectively of one part to at least three parts, by weight, with the total amount of both components constituting from to by weight, of the entire solution.

2. A composition adapted to form strongly adherent films on metal surfaces comprising a polyorganosiloxane which is a copolymer of arnyl trichlorosilane and triethoxysilane, a chlorinated parafiin wax containing about 30911110 40% chlorine, and a readily volatile solvent carrier for the aforesaid components, the first two components being in relative proportions respectively of one part to at least three parts, by weight, with the total chlorinated parafiin wax containing about 30% to 40% t 6 amount of both components constituting from 5% to 10% by Weight, of the entire solution.

3. A composition adapted to form strongly adherent films on metal surfaces comprising a polyorganosiloxane derived from the condensation of ethyl dichlorosilane, a

chlorine, and a readily volatile solvent carrier for the aforesaid components, the first two components being in relative proportions respectively of one part to at least' three parts, by weight, with the total amount of both components constituting from 5% to 10%, by weight, of the entire solution.

4. A composition adapted to form strongly adherent films on metal surfaces comprising a polyorganosiloxane which is a copolymer of amyl trichlorosilane and triethoxysilane, a chlorinated parafiin wax conitaining about chlorine, and a solvent of trichloroethylene, the first two components being in relative proportions respectively of one part to at least three parts by weight, with the total amount of both components constituting from 5% to 10% by weight of the complete solution.

5. A composition adapted to form strongly adherent films on metal surfaces comprising one part of a polyorganosiloxane derived from the condensation of ethyl dichlorsilane, to at least three parts of a chlorinated parafiin wax containing about 40% chlorine, and a solvent of trichloroethylene in amounts to produce a 5% to 10% total weight solution of the first two components.

References Cited in the file of this patent UNITED STATES PATENTS 1,991,395 Kocour Feb. 19, 1935 2,126,590 Valentine Aug. 9, 1938 2,223,037 Ihrig Nov. 26, 1940 2,329,731 Spring Sept. 21, 1943 2,406,971 Sowa Sept. 3, 1946 2,470,062 Whitbeck May 10, 1949 2,471,850 Wilcock May 31, 1949 2,613,626 Whitney 'Oct. 14, 1952 2,623,019 Wilcock et al. Dec. 23, 1952 OTHER' REFERENCES The Modern Industrial Press, pages 6, 8, 20, September 1947.

Claims

1. A COMPOSITION ADAPTED TO FORM STRONGLY ADHERENT FILMS ON METAL SURFACES COMPRISING A POLYORGANOSILOXANE HAVING ALKYL SUBSTITUENTS AND HYDROGEN BONDED TO THE SILICON ATOMS, A CHLORINATED PARAFFIN WAX OF EXTREME PRESSURE LUBRICATION CHARACTERISTICS, AND A READILY VOLATILE SOLVENT CARRIER FOR THE AFORESAID COMPONENTS, THE FIRST TWO COMPONENTS BEING IN RELATIVE PROPORTIONS RESPECTIVELY OF ONE PART TO AT LEAST THREE PARTS, BY WEIGHT, WITH THE TOTAL AMOUNT OF BOTH COMPONENTS CONSTITUTING FROM 5% TO 10%, BY WEIGHT, OF THE ENTIRE SOLUTION.