SE191482C1 - Razor blade and procedure for its manufacture - Google Patents

Abstract

The cutting edge of a safety razor blade is coated with a solid fluorocarbon polymer as defined. The coating is baked. The blade may be made of hardened carbon or stainless steel, other metals or metal alloys. The fluorocarbon polymers, which are solid polymers containing a plurality of (-CF2-CF2-) groups with or without terminal carboxyl groups, hydrogen and chlorine atoms, e.g. P.T.F.E., may be applied by sublimation, electrophoresis from charged liquid dispersions thereof, dipping in a dispersion of the particulate fluorocarbon polymer in a volatile liquid or spraying or brushing such dispersions. The volatile liquid may be water, dichlorodifluoromethane, dichlorotetrafluoroethane, trichlorotrifluoroethane and mixtures thereof. In the examples, steel blades are washed and dried and then coated by one of the above methods. If a dispersion is used then the volatile liquid is evaporated before carrying out the baking step. The baking step may be carried out simultaneously with the depositing step.ALSO:A dispersion of solid fluorocarbon polymer, as defined, p contains as dispersing agent water, dichlorodifluoromethane, dichlorotetrafluoroethane, trichlorotrifluoroethane or mixtures thereof. The fluorocarbon polymer contains a plurality of (-CF2-CF2-) groups with or without terminal carboxyl groups, hydrogen and chlorine atoms, e.g. P.T.F.E. The dispersion is used to coat razor blades.

Description

CLASS INTERNATIONAL SWEDISH B 26 b69: 21/02 PATENT AND REGISTRATION AGENCY Ans. 12 678/11160 was received on 30/12 1960 published on 27/1 1964 THE GILLETTE Co., BOSTON, MASS., USA Razor blades for its production Inventors • IW Fisebbein Priority requested (rob on 31 December 1959 (USA) Existing The invention further relates to razor blades having one or two edges, and more particularly to a razor blade which is improved by having its cutting edge provided with an adhesive coating containing a fluorocarbon which improves the shaving ability of the blade.The invention further relates to a method of making such razor blades.

Usual steel razor blades, p0. which the present invention can be filampased, have a thickness of 0.075 to 0.375 mm and have wedge-shaped cuttings, the angle of which encloses the material, is greater than 14 ° and less than 35 °. The facets or sides of some such cut edges stretch: themselves, shaved frail front edge and baked, over a stretch of 2.5 mm and more. Each edge of the edge does not necessarily consist of a single continuous flat facet, but may consist of two or more facets, which are formed by successive grinding or honing and which intersect along zones which are usually parallel to the actual edge of the edge. The last facet, ie. the fa-set, which examines immediately next to the actual edge of the edge, may have a width, as in comparison with diameter. of a skaggstra, which on average amounts to about 0,10,125 mm, Sr small and amounts to about 0,0075 mm, while the thickness of the actual edge itself itself is usually less than 0.6 / 2 and preferably less than 0, / L . The razor blade is made of either carbon steel or hardenable stainless steel. In this case, the blade hardens through a suitable heat treatment. The degree to which the blade can be heated afterwards, Sr limited, because a repeated, alai & vigorous heating leads to a loss of hardness. As Oman's rule states, the hardened metal blade edges must not be exposed to the effects of a temperature above 205 ° C for more than four minutes, otherwise unites & Wet anneals and becomes soft, which is why with a type of Dupl. at 22 g: 7/01; 69:25; 75 c: 5/01 fluorocarbon granules are set for the mine and set by the treatment. The coating can, however, Sven pifora's leaves, whose cuttings apart frail sta. ' or stainless steel.]. best. of other metals or metal alloys or are coated therewith, the highest temperature to which these other metals or metal alloys may be exposed without name change of the physical properties, as is known, may be within a wide range. & As is well known, the usual steel razor blades, despite their sharpness, can only be used during pain and discomfort for shaving a dry shag, Tad & in general a shaving softener, for example water and / or a shaving frame or shaving choice must be used. The discomfort and the pain caused by dry shaving is due to the excessive force required to pull the blade's scarlet edge through the unsoftened shaggy strands, this force being transmitted to the nerves in the skin near the hair follicles from which the shaving strands emerge. ; As is well known, the smartness which is achieved by excessive pulling in these strands can continue for quite some time after the pulling has ceased.

Attempts have certainly not been lacking to achieve a facilitation of shaving and in particular a reduction of this attraction, not only through a pre-treatment of the shavings, but Sven through the application of coatings of various kinds. the magazine; However, the coatings known on razor blades do not lead to a significant improvement in the cutting properties of the razor blade. Coatings on razor blades have served other purposes, such as raising the rust resistance, determining the leaf's crush condition, etc. Coatings of liquid, especially oily, materials, soap, wax, camphor, plasticizers, such as cellulose derivatives, graphite are known. , alumina, nickel, rhodium, etc. None of these coating materials have given the same results as the invention. Especially when using graphite as a coating material. assumed that it has a very low coefficient of friction; against the expectations, however, rapid coatings of graphite and other materials mentioned above of a softer and frictionless nature have shown that they give a. in comparison with the coating according to the invention only insignificant or joke any improvement ails towards coating-free leaves.

The downside is that it has also already been proposed to impose on the cutting edge an adherent coating of an organic gel of the silicon type, which is polymerized in superheated steam. In contrast to other proposals, to start from such a basic substance for the coating, which is relatively soft (gel-like), the invention stands out, according to which coating compounds of solid fluorocarbon polymers are used, which are known to be hard and tough, e.g. a. of a simplification of the production process by making the polymerization conditions less critical.

The invention relates to a razor blade with the feature that it has a coating of solid fluorocarbon polymers which adheres to a cutting edge, which contain a chain of carbon atoms with a number of (-CF2-CF2-) groups.

A razor blade with such a skareggsbelfiggping in the form of a solid fluorocarbon polymer has, quite surprisingly, a remarkably longer lingering, higher shaving shape than all hitherto known razor blades with skareggsbelfiggning. This improvement is noticeable through a reduction in the pull, ie. by a reduction of the force required for cutting the shaggy strands, whereby the shaving is easier and more comfortable, said that if said. If desired, the usual softening of the beard can be shortened, since the softening of the beard is not of such importance as when using ordinary razor blades. The blades according to the invention, when examined under carefully controlled conditions, cut off water-softened strands required much less force than the same blade without coating. This reduction in traction can last for several consecutive shaves but does not last indefinitely.

Coatings of the fluorocarbons and also of those with the above structure on various objects, also of metallic kind, are already in place. kanda. However, only the lower coefficient of friction, the heat resistance and the property of these fluorocarbons have been used. sticky * span on the side surfaces of the teeth and saw blade, f Or that mom bakery technology bear-beta sticky sugary material without risk of sticking to the work tool, f Or that in medical needles facilitate insertion into the linden, to coat scalps, so that nothing sticks to them , etc. If the bakery is made of fluorocarbon material completely existing, ie uncoated knives with straight or round edges are used for the distribution of sugar mass, dough or other sticky materials. Not: If any of the aforementioned areas of use, it is a question of an improvement of the cutting properties. these kanda usesoinraden differ folj actual actually pri ncipially fan the invention, which relates to a completely different and peculiar problem, namely to shorten, by cutting, a formation formed in it in only one spirit. type, as a skaggstra constitutes and on the basis of these, these known forms of use joke the painter gives some guidance for solving the problem of the invention. The person skilled in the art could also read something from the general instructions on friction in and lubrication of solid materials in a laro book, which contains information on the coefficients of friction of various non-metallic substances, hi. a. Graphite and polymer compounds of the fluorocarbon, polyethylene, polystyrene, etc. type As already stated above, the comparative experiments with similar substances concerning their ability to improve the shaving properties of a razor blade have shown that there is no apparent correlation between coefficient of friction and shaving properties. Dail & could the expert joke also get some male reference from the general 151.0135cker, that a razor blade with the above type of coating of the fluorocarbons has extremely favorable shaving properties.

The fluorocarbon coating or stripping can extend from the actual cutting edge and bake over the entire wedge-shaped surface and even longer or only thank the part of the final facet adjacent to the actual cutting edge. The exact thickness of the coating is apparently not critical and a thinner continuous, adherent coating of a thickness of the same order of magnitude as a layer of oriented molecules has been found to be effective for the spirit of the present invention. The coating does not need to have a uniform thickness throughout. extent.

The fluorocarbon materials which can be used according to the invention constitute solid substances and comprise various solid polymers of tetrafluoroethylene, which contain a chain of carbon atoms with a number of (-CF2-CF2 -) - - —3 groups. The molecular weight of these polymers, in the form in which they are pafora, can range from 2000 to even less than 2,000,000 and above. Even with very high molecular weight polytetrafluoroethylene in non-degraded form, advantages are obtained when used as a coating on razor blades of carbon steel, although the results are not so satisfactory, since this coating material is better suited for blades made of other metals or metal alloys. The duct groups in the carbon chains can also vary in pH and size, depending on the process used in the preparation of the polymer. Polymers prepared in aqueous media have carboxyand groups, while in other polymers vate and / or chlorine atoms are attached to the duck carbon atoms in the chain.

When using the high molecular weight fluorocarbon, the material on the blade's cutting edge is preferably ground on its salt, that the cutting edge is placed near a supply of fluorocarbon, while this is heated, whereby a coating of degraded fluorocarbon is precipitated on the cutting edge by sublimation. Electrophoresis can also be used for precipitation of a high molecular weight material from charged liquid dispersions or the cutting edge can simply be dipped into the dispersion and then left to dry.

Solid fluorocarbons of relatively low molecular weight can likewise be formed into the salt on the salt, which is immersed in a dispersion of the special fluorocarbon, in a volatile liquid medium or that the dispersion is sprayed on the scar or palores with a brush, after which the liquid medium is evaporated. Volatile, liquid usable media constitute hi. a. water and under the tradename Freoner kanda compounds, such as dichlorodifluoromethane, dichlorotetrafluoroethane, trichlorotrifluoroethane and their mixtures.

Regardless of the manner in which the solid fluorocarbon is applied to the cutting edge, the blade with the predetermined solid fluorocarbon must be cured at an elevated temperature of about 90400 ° C, for such a period of time that the fluorocarbon becomes firmly adhered to the substrate. High-molecular-weight fluorocarbons must be heated almost to the upper limit of the temperature range, while relatively low-molecular-weight fluorocarbons do not require their high temperatures. The time can vary from less than 2 minutes and up to 48 hours depending on the particular fluorocarbon used, the nature of the substrate, the rate at which the coated sheet is heated, and the temperature reached. Stable leaves should not be heated for more than four minutes at a temperature of at most 205 ° C, so that the leaves, as already mentioned, should not be touched or softened. In the case of blades of certain other materials, in particular stainless steel, a limited grinding or tarnishing of the blades, since the associated impurities can more than possibly be offset by the improved shaving effect achieved according to the invention. In general, the steel blades must be heated for at least N minutes at 150-160 ° C in order to obtain the best results, even if a prolonged heating does not damage the coating. In some cases it is possible to heat the blade before or during the application of the solid fluorocarbon, whereby the curing is carried out at the same time as the application.

Although, as already mentioned, the coating on the cutting edge of the blade, which is ready for use, is extraordinarily thin, for the production of such a coating, it is desirable that the coating at the beginning of the hardening is considerably thicker. All the excess material remaining in the pH scar, which does not bond to the substrate during curing, is in the form of a loose film which can be easily removed by brushing or rubbing. However, it is important to remove this excess material before using the blade.

Since it is not possible to ascertain exactly the nature of the formation of the coating, it is assumed, without limiting the invention, that a coalescence of at least some solid fluorocarbon particles occurs and that a mutual effect occurs between the fluorocarbon and the underlying surface, e.g. thereby creating a strong bond between the fluorocarbon and the substrate. The resulting thin adhesive coating, which was mechanically carried up throughout its extent by the underlying blade, reduces the pull during shaving and makes shaving easier and more comfortable.

The invention is further illustrated by the following examples. It was found that all the treated leaves in actual shaving tests have remarkably improved shaving properties in comparison with the same kind of blades which are not treated according to the invention.

Example 1. 500 mg of solid tetrafluoroethylene polymer (in the form of pieces, cut from a trade name Teflon kand folic) was filled into a ceramic tube lined with stainless steel (the thickness of the stainless steel layer was 0.75 mm; the length of the ceramic tube was 50.8 mm, its diameter 11.11 mm and its cradle thickness 1.6 mm) The ceramic tube was heated by a. electric current was passed through a helical tungsten wire, with a thickness of 1 nun, which was wound around the ceramic tube with 30 vary per 50.8 mm. A razor blade of hardened carbon steel with a thickness of 0.125 mm and which has been pre-cleaned by washing with trichlorethylene and dried, was placed with its cutting edge against the open edge of the tube at a distance of 4 cm from it. The whole was then placed in a vacuum cabinet, which was evacuated to a pressure of -4 mm Hg. The tungsten coil was then electrically heated until the crucible temperature reached 370,100 ° C. was then regulated so that a pressure of 3X-4 mm Hg was maintained during the heating, which was continued for four hours. The blade was then removed and showed a precipitated layer on the cutting edge, which showed interference characteristics in the light microscope. The blade was then placed in an air oven at 160 ° C for 40 minutes.

Example 2. A stainless steel razor blade, purchased at the Open Market, was thoroughly cleaned by washing with trichlorethylene and dried. Its cutting edge was then immersed in a colloidal aqueous dispersion containing 25% by weight of finely divided solid tetrafluoroethylene polymer (Teflon Clear Finish, sold by E. I. DuPont de Nemours and Co., Inc., Wilmington, Delaware, A.f.s.). When removed from the dispersion, a coating of the aqueous dispersion was present on the blade edge, which was dried for one hour at about 50 ° C in air, after which the coating was cured for seven minutes at 400 ° C.

Example 3. A finely divided solid fluorocarbon polymer comprising a chain of carbon atoms having a number of (--CF2-CF2 -) groups and also a smaller number (about 1% by weight) of chlorine atoms and an equal number of hydrogen atoms and having a melting range of 265 -295 ° C (Fluorowax TLT-17, Lot No. 2, flan the American company listed in Example 2) was dispersed in a mixed mug of Freon 12 (dichlorodifluoromethane) and Freon 114 (dichlorotetrafluoroethane) in a weight ratio of 40:60, a dispersion was formed which contained 1% by weight of dry matter. This dispersion was sprayed from a pressure vessel onto the cutting edge of a razor blade of the type described in Example 1, which razor blade was pre-cleaned on salt described in the previous example, after which the blade was cured for seven hours in an air oven at a temperature of 165 ° C.

Example 4. The fluorocarbon polymer described in Example 3 was dispersed in Freon 113 (trichlorotrifluoroethane) to a dispersion with a content of 1% by weight of dry matter. The cutting edge of a razor blade of the type described in Example 1, which razor blade was cleaned in the manner described above, was immersed in this dispersion and then allowed to dry in the air. The blade was then heated for 10 hours at 160 ° C. Similar results were also obtained using similar dispersions with one. content of up to 11% by weight of fluorocarbon polymer.

Example 5. The solid fluorocarbon described in Example 3 was applied to the cutting edge on a razor blade as described in Example 1 in the same manner described in the same example except that the crucible temperature was maintained at about 165 ° C and that heating was continued for 10 minutes. The blade was then removed from the vacuum cabinet and showed interference colors on the cutting edge. Similar results can be obtained by heating at a temperature of about 120 ° C for a long time. The coated sheets according to one of these were then placed in an air oven and stored for 15 minutes in it at a temperature of 160 ° C. Similar results are obtained when the heating is carried out for 16 hours at the same temperature in the air oven.

Example 6. The solid fluorocarbonate described in Example 1 was heated in air at atmospheric pressure in a silica crucible to a temperature of about 2 ° C, until a thick white smoke continuously developed from the crucible. A razor blade of the type described in Example 1, cleaned in the manner described above, is held with its edge in the white rim at a distance of 75 mm from the crucible for 10 minutes. Due to the proximity of the crucible, the blade assumed a temperature of about 150 ° C during the precipitation of the fluorocarbon on the cutting edge of the blade, whereby a further hardening was unnecessary.

Claims (12)

Patent claim: Razor blades, characterized by a coarse-grained coating of solid fluorocarbon polymers, which contain a carbon chain with a number of (-CF2-CF2-) groups. Blade according to claim 1, characterized in that the coating consists of a solid tetrafluoroethylene polymer. Blade according to claim 1 or 2, characterized in that the polymer has andp-upper, which consist of carboxy groups, hydrogen atoms and chlorine atoms. Blade according to one of claims 1 to 3, characterized in that the razor blade is made of hardened steel. Blade according to any one of patent claims 1-4, characterized in that the razor blade is made of stainless steel. 6. A method of making a razor blade according to any one of claims 1-5, characterized in that the solid fluorocarbon is ground to a hardened cutting edge of the blade and that it is heated under conditions in which no excessive loss is made of the hardness of the blade and wherein a adhesive coating is formed on the edge. 7. A method according to claim 6, characterized in that a dispersion of individual particles of the solid fluorocarbon in a volatile liquid is pafores the sheet, after which the liquid is evaporated. 8. A method according to claim 7, characterized in that the volatile liquid used is water. 9. A process according to claim 7, characterized in that the volatile liquid used is dichlorodifluoromethane, dichlorotetrafluoroethane, trichlorotrifluoroethane or their mixtures. 10. A method according to claim 6, characterized in that the fluorocarbon is polished to the edge of the salt so that it is affected by the fluorocarbon. A method according to any one of claims 6-10, characterized in that the heating is carried out for at least 30 minutes at a temperature of 150-160 ° C. 12. A method according to any one of claims 6-11, characterized in that the heating and pafing of the coating is carried out simultaneously. Request Publications: U.S. Patent Nos. 2,855,669.