US3420702A

US3420702A - Double bath treatment of cellulosic fabrics to impart crease resistance and high abrasion resistance thereto

Info

Publication number: US3420702A
Application number: US454985A
Authority: US
Inventors: Myrtle Joanne Spangler
Original assignee: Dan River Mills Inc
Current assignee: Dan River Mills Inc
Priority date: 1965-05-11
Filing date: 1965-05-11
Publication date: 1969-01-07
Anticipated expiration: 1986-01-07

Description

United States Patent 3,420,702 DOUBLE BATH TREATMENT OF CELLULOSIC FABRICS T0 IMPART CREASE RESISTANCE AND HIGH ABRASIGN RESISTANCE THERETO Myrtle Joanne Spangler, Danville, Va., assignor to Dan River Mills, Incorporated, Danville, Va., a corporation of Virginia N0 Drawing. Filed May 11, 1965, Ser. No. 454,985 US. Cl. 117-13.4 4 Claims Int. Cl. D06m 15/48 ABSTRACT OF THE DISCLOSURE Method of manufacturing fabrics capable of being formed into crease resistant articles having high abrasion resistance comprising the steps of impregnating the cellulosic fabric with a copolymer comprising about 49 to 50 weight percent polymerized ethyl acrylate, about 49 to 50 Weight percent polymerized butyl acrylate and about 2 to 2.7 weight percent methylol acrylamide, removing moisture from the impregnated fabric and thereafter impregnating with a crease proofing chemical and drying the resulting impregnated fabric.

The present invention relates to the manufacture of cellulosic textile fabrics capable of being permanently creased or shaped. In particular, this invention relates to such textile fabrics that are characterized by very high crease retention, very high appearance rating and greatly improved abrasion resistance and, more particularly, relates to allcotton fabrics having these properties.

A serious problem existing in the textile industry is the low abrasion resistance of cotton fabrics treated with crease resistant chemicals. This problem is particularly severe when aminoplast resins are applied to all-cotton fabrics and dried or partially cured thereon to produce a sensitized fabric which then is cut and sewn into garments or other textile articles, followed by pressing or other shaping procedure, and curing to make the shape of the garment durable to laundering and wrinkle resistant.

It has been found heretofore that garments made from sensitized all-cotton fabrics quickly wear out through use or laundering at weakened portions thereof, such as at the angle of creases and pleats.

At the present time a solution to the problem has been to use stronger fibers, such as polyester fibers blended with cotton fibers, as the base fabric which is treated to produce the sensitized fabric. The stronger synthetic fiber increases the abrasion resistance of the fabric and, in effect, extends the life of the garment or article made therefrom. While the use of polyester fibers has enabled the extensive application of sensitized fabrics made therefrom, the problem of lack of abrasion resistance of treated all-cotton fabrics remained to be solved. Also, While the use of synthetic fibers reduced the problem to a tolerable level, the problem still existed and became increasingly severe as the amount of synthetic fiber in the fabric was reduced.

Acrylic polymers have also been employed in small amounts in the past for the purpose of improving the abrasion resistance of cellulosic fabrics treated with aminoplast creaseproofing agents. It had been found, however, that when the acrylic polymer was employed in amounts of more than 3.5% by weight of the fabric, the crease resistance of the resulting treated fabric progressively diminished (United States Patent No. 2,952,892, col. 2, lines 6-13). It was also previously understood by skilled workers in the textile finishing industry that to increase the amount of acrylic polymer above 3 to 4% based on the Weight of the fabric does not provide any commensurate increases in abrasion resistance.

It is a principal object of this invention to provide a method for treating cellulosic textile fabrics whereby garments made from such treated fabrics are crease resistant and abrasion resistant.

Another object is the provision of a fabric treatment for sensitizing cellulosic textile fabrics whereby articles made from the sensitized fabric are greatly improved in appearance rating, crease retention and abrasion resistance.

Another object is the provision of sensitized all-cotton fabrics which are capable of being formed into garments having superior appearance ratings, crease retentions and abrasion resistances.

Another object is the provision of fabrics which are crease resistant, shape retentive, high in appearance rating and of superior abrasion resistance.

Further objects and advantages will be apparent from the following detailed description.

It has been unexpectedly found that when a cellulosic textile fabric is impregnated with an aqueous dispersion of an acrylic polymer and thereafter impregnated with an aqueous dispersion of a textile creaseproofing aminoplast and thereafter dried and/or cured, there results a wrinkle resistant fabric characterized by a greatly improved resistance to abrasion and having improved color retention. In those cases where the impregnated fabric is dried without curing or is dried with partial curing so as to leave a substantial reactivity in the fabric, there results a sensitized fabric which can be formed into garments or other textile articles which can be creased or otherwise shaped and then cured to render the crease or shape durable.

In its most important aspect, the present invention permits the use of all-cotton fabrics or fabrics having major amounts of cotton and minor amounts of synthetic or other fibers, as the base fabric in the production of sensitized fabrics for use in the manufacture of permanent press garments. The term synthetic or other fibers is intended to include rayon fibers, polyester fibers, such as Fortrel (registered trademark of Fiber Industries, Inc.), which is a polyester comprising a polymerized polycondensate of terephthalic anhydride and ethylene glycol; nylon; polymers containing at least percent polymerized acrylonitrile, such as those available commercially under the trade names Orlon and Acrilan, and so on. Staple synthetic fibers, or continuous synthetic filaments, as desired, can be employed in the Ways that are well known in the art. This invention, nevertheless, can be applied with advantage to any woven or knitted cellulosic fabric with or without any amount of synthetic or other fiber. The term cellulosic textile fabric as used herein means any of the above-described fabrics, including blends which contain cellulosic fibers such as cotton, rayon and the like.

Acrylic polymers which may be used herein include polymers of esters of acrylic acid or methacrylic acid with cyclohexanol or alkanols having 1 to 18 carbon atoms and include polymers of more than one acrylic monomer, such as the above-mentioned esters, acrylonitrile, acrylic acid, methacrylic acid, itaconic acid and the like. Especially preferred are the ethyl acrylate polymers.

In addition, other acrylic monomers, such as N-methylol acrylamide, acrylonitrile and the like, can be copolymerized with the ethyl acrylate in the presence or ab- Sence of the other said acrylic monomers and employed herein. Examples of suitable ethyl acrylate polymers include a polymer of ethyl acrylate, butyl acrylate and N- methylol acrylamide or a polymer of a major amount of ethyl acrylate and a minor amount of methyl meth- 3 acrylate. The particular ethyl acrylate polymer employed will depend upon the type of fabric, i.e., the type of weave of the fabric, employed and the type of hand desired on the fabric. For example, for softer hands, softer acrylics, such as ethyl acrylate-butyl acrylate copolymers would be employed, whereas for stiffer hands, polymers of ethyl acrylate and methyl methacrylate and the like would be employed. In general, the alkyl acrylates impart softness whereas the alkyl methacrylates impart stiffness or hardness. Other acrylic polymers equivalent to the ethyl acrylate polymers as defined above can be employed in place of such ethyl acrylate polymers.

The acrylic polymer is dispersed in a first treating bath in an amount of at least 4%, preferably at least 6.5%, by weight of the treating bath but amounts above about 18% do not appear to provide a commensurate advantage over lower amounts.

The aminoplast employed is any resin-forming condensate of formaldehyde or equivalent materials, such as paraformaldehyde, with urea, N,N-ethylene urea, N,N'- trimethylene urea, melamine, l,3-dimethylol-4,5-dihydroxy-2-imidazolidinone, also known as 1,3-dimethylol-4, S-dihydroxyethylene urea, acetylene diurea, tetrahydro-striazones having the formula HO CHa-N N-CHzOH HnC OH:

wherein R is selected from the group consisting of 2- hydroxyethyl, Z-methyl-Z-hydroxyethyl, and alkyl groups having 1 to 4 carbon atoms; and the like. 1,3-dimethylol- 4,5-dihydroxy-2-imidazolidinone is of especially important use in producing sensitized fabrics useful for the manufacture of garments and articles having durable creases or other durable shapes. The aminoplast treating bath contains from 1 to 20% of the aminoplast based on the weight of the treating solution.

In addition to the aminoplast, e.g., 1,3-dimethylol-4,5- dihydroxy-2-imidazolidinone, the treating bath also contains a sufficient amount of catalyst to induce the proper curing of the aminoplast. Amounts of catalyst will depend upon the type of catalyst, the type of aminoplast and the type of fabric being treated. Generally, the catalyst will be present in the treating bath in amounts ranging from 0.1 to by weight of the treating bath. Suitable catalysts include zinc nitrate, magnesium chloride, zinc fluoborate, magnesium perchlorate, zinc perchlorate, phosphoric acid, tartaric acid, oxalic acid, zinc chloride, aluminum chloride and other acidic curing catalysts including the amine hydrochlorides, such as the hydrochloric or other acid salts of hydroxyaliphatic amines, including monoethanol amine, diethanol amine and the like.

While the first and second treating baths can contain suitable amounts of other materials, e.g., softeners, wetting agents, anti-stick agents, etc., it is preferred that materials should not be added which would seriously deteriorate or destroy the yarn-penetrating qualities of the bath. The second treating bath containing the aminoplast condensate can also contain water repelling agents and the like for providing special effects to the fabric as desired.

The fabric, after impregnation in the first treating bath, can be directly immersed in the second treating bath or it can be squeezed and/or dried at ambient temperatures or at elevated temperatures to remove moisture prior to immersion in the second treating bath. The removal of moisture is important only when it is necessary to provide additional absorbing capacity for the second impregnation. It is possible to conduct the first impregnation in a manner which would provide suflicient pick-up of the first treating bath but allow to remain sufficient absorbability for the second treating bath. Present mill practices and capabilities, however, indicate the preference of adjusting moisture content by squeezing or drying after the first impregnation but before the second impregnation. Any method and/or means can be employed in assuring the disposition of the amounts of acrylic polymer and aminoplast as hereinafter set forth.

The impregnations can be performed in any suitable manner, preferably by padding techniques. The fabric should be impregnated with 50 to 100%, preferably 55 to of the treating baths based on the fabric weight. The amount of acrylic polymer disposed in the fabric should be at least 2.4% and the amount of aminoplast should be at least 3.0% based on the weight of cellulosic fibers in the fabric. Substantially higher amounts of acrylic polymer and aminoplast can be used, for example, as high as 6% or more of acrylic polymer and 8% of aminoplast based on the weight of cellulosic fibers in the fabric.

After the second impregnation, the fabric can be dried by air drying at normal room temperature or drying at elevated temperatures. The drying at elevated temperatures can be sufficiently severe as to cause partial or full curing. If it is desired to produce a sensitized fabric, the drying can be conducted so as to avoid any substantial curing whatever or it can be so conducted as to impart a partial curing leaving suflicient reactivity in the fabric to enable the formation of a crease or other shape in the fabric followed by curing to render the crease or shape permanent.

In general, time and temperature of drying and type of fabric determine the extent, if any, of partial curing. The higher the temperature and/or the longer the time, the gerater will be the extent of curing. Of course, when air drying at room temperature is employed, no substantial curing would be expected. At temperatures below about 200 F. very little, if any, curing would be expected to result. The impregnated fabric can be dried at temperatures of 250 F. or more for short periods of time without incurring any large amount of curing, if any at all. Temperatures of 250 F. and above for longer periods of time, for example, two minutes or more, will initiate partial curing. Higher temperatures, for example, about 340 F., and times of three or four mintues will result in extensive curing and, in some cases, complete curing. The precise conditions of drying and/or curing will be quite obvious to a skilled worker after having selected the specific desired end result. The drying and partial curing, if desired, can be carried out in a single operation utilizing a single temperature zone or a two-step operation employing two temperature zones. If desired, the fabric can be fully cured, in which event it has no substantial reactivity and is not a sensitized fabric.

When a sensitized fabric is produced according to this invention, it is stable to storage for many months without losing a substantial portion of its reactivity, if the proper aminoplast resins, e.g., 1,3-dimethylol-4,S-dihydroxyethylene urea, have been chosen. After shipment of the sensitized fabric to the garment manufacturer, it can be cut and sewn into a garment which is then creased or otherwise shaped by pressing or the like, and then cured to render the crease or shape permanent. Curing ovens for accomplishing the final cure are now available to many large garment manufacturers. It is possible, also, to effect the final curing through the use of specially made presses. Creased or shaped garments having appearance ratings in excess of 5, crease retentions in excess of 5 and Accelerotor abrasion losses of as low as 4.6 can be made in this way from sensitized fabrics according to this invention.

The following examples are presented. In these examples all percentages and parts are by weight, appearance ratings were determined in accordance with A.A.T.C.C. Tentative Test Method 884960, all crease retention values were determined in accordance with A.A.T.C.C. Tentative Test 88Cl96 2T, crease resistance values were determined by the Monsanto Crease Recovery Test (A.A.T.C.C. Tentative Test Method 66- 1955T) and all temperatures are in degrees Fahrenheit, unless otherwise specified. The Accelerotor abrasion tests were conducted by running a piece of the cloth in an Accelerotor according to A.A.T.C.C. Tentative Test Method 93- 1959T for four minutes at 3000 r.p.m. and comparing the weight of the cloth before and after running in the Accelerotor test. The percentages set forth hereinafter for the Accelerotor abrasion tests represent the weight loss of the fabric after undergoing the Accelerotor test. Destruction in the Accelerotor test is indicated when large tears appear in the fabric and when the fabric hangs up on the impeller of the Accelerotor. All treating baths are aqueous solutions or dispersions. Rhoplex B is made and sold by Rohm & Haas Company as an approximate 46% solids aqueous nonionic dispersion having a pH of about 6.5 and being miscible with water in all proportions. Analysis shows the solids content of B-15 to be predominantly polymerized ethyl acrylate and a small amount of polymerized methyl methacrylate. Rhoplex K-3 is made and sold by Rohm & Haas Company as a 45% solids nonionic aqueous dispersion having a pH of 2.8 to 3.0, having a specific gravity of 1.04 and being miscible with water in all proportions. Analysis shows the solids content of K-3 to be polymerized butyl acrylate and ethyl acrylate in the approximate amounts of about 50' weight percent butyl acrylate and about 50 weight percent ethyl acrylate containing a small amount of an amine-formaldehyde in an amount which, as methylolacrylamide, calculates 2.7 weight percent of the copolymer.

Example 1 Five treating baths were prepared as follows:

Treating Bath 1 contained of an aqueous solution containing three parts by weight of an approximately 50% solids aqueous solution of 1,3-dimethylol-4,S- dihydroxyethylene urea and 2 parts by weight of a 40% solids aqueous solution of a polymethylated polymethylol melamine having an average of about four and one-half methoxymethyl groups and about one-half methylol group bonded to nitrogen; and 3% of a 64% solids aqueous solution of magnesium chloride hexahydrate.

Treating Bath 2 contained 15% of an aqueous solution containing three parts by weight of an approximately 50% solids aqueous solution of 1,3-dimethylol-4,5- dihydroxyethylene urea and 2 parts by Weight of a 40% solids aqueous solution of a polymethylated polymethylol melamine having an average of about four and one-half methoxymethyl groups and about one-half methylol group bonded to nitrogen; and 3% of a 64% solids aqueous solution of magnesium chloride hexahydrate.

Treating Bath 3 contained 15% Rhoplex B-lS (previously identified).

Treating Bath 4 contained 20% of an aqueous solution containing three parts by weight of an approximately 50% solids aqueous solution of 1,3-dimethylol- 4,5-dihydroxyethylene urea and 2 parts by weight of a 40% solids aqueous solution of a polymethylated polymethylol melamine having an average of about four and one-half methoxyrnethyl groups and about one-half methylol group bonded to nitrogen; 3% of a 64% solids aqueous solution of magnesium chloride hexahydrate; and 15% Rhoplex B-15.

Treating Bath 5 contained 15% of an approximately 50% solids aqueous solution of 1,3-dimethylol-4,5-dihydroxyethylene urea; 3% of a 64% solids aqueous solution of magnesium chloride hexahydrate; and 15% Rhoplex B-15.

Six pieces of black, regular Weight, close weave, allcotton twill were treated as follows:

Fabric A was padded through Treating Bath 1 to an approximate 60% wet pick-up.

Fabric B was padded through Treating Bath 2 to an approximate 60% wet pick-up.

Fabric C was padded through Treating Bath 3 to an approximate 60% wet pick-up and then air dried and' pressed for 20 seconds. It was then padded through- Treating Bath 1 to an approximately 60% wet pick-up.

Fabric D was padded through Treating Bath 3 to an approximate wet pick-up of 60%. It was then air dried and pressed for 20 seconds. It was then passed through Treating Bath 2 to an approximate wet pick-up'of 60%.

Fabric E was padded through Treating Bath 4 to an approximate wet pick-up of 60%.

Fabric F was padded through Treating Bath 5 to an approximate wet pick-up of 60%.

All fabrics as' treated above were air dried, creased and pressed and then cured for 4 minutes at 170 C. The resulting treated fabrics had the following properties:

TABLE I Aceelerotor Fabric Crease retention Appearance rating abrasion (percent loss) 5 5 Destroyed 5 4-5 Destroyed 5 5 7. 3 5 4-5 7.0 5 5 14. 3 5 5 15. 4

is to be noted that Fabrics C and D had approximately one-half the abrasion loss as Fabrics E and F. Fabrics A and B, which contained no acrylic polymer, were destroyed in the A-ccelerotor abrasion test. Fabrics C and D, covered by the present invention, are thus far superior to the case where no acrylic polymer is employed and the case where the acrylic polymer is included in the same treating bath as the aminoplast condensate. Fabrics C and D retained far more color than did the remaining fabrics.

Example 2 A treating bath was prepared comprising 15% Rhoplex K3 as identified above and 1% of a 64% solids aqueous solution of magnesium chloride hexahydrate. An all-cotton fabric was padded through the treating bath to a 60% wet pick-up, air dried and then pressed for 10 seconds. The thus treated fabric was padded through a treating bath containing 20% of an approximately 50% solids aqueous solution of 1,3-dimethylol-4,S-dihydroxyethylene urea and 2%of a 64% solids aqueous solution of magnesium chloride hexahydrate, was air dried and partially cured for 70 seconds at C. Thereafter the fabric was creased by pressing and then cured 4 minutes at 340 F. The resulting cured, creased fabric had a crease retention of 5, an appearance rating of 5 and an Accelerotor abrasion value of 10.4% loss. The fabric also retained far more color on laundering or after the abrasion test than comparable fabrics treated by the same method but using Rhoplex B-15 in place of Rhoplex K-3.

Example 3 A treating bath was prepared comprising 31% of a 40% solids aqueous dispersion of an acrylic polymer containing 49% polymerized ethyl acrylate, 49% polymerized butyl acrylate, and 2% N-methylol acrylamide; 8% of a sodium salt of sulfated polyoxyethylated alkyl phenol and 52% water; and 1% of a 64% solids aqueous solution of magnesium chloride hexahydrate. An all-cotton fabric was padded through the treating bath to a 60% wet pick-up, air dried and then pressed for 10 seconds. The thus treated fabric was padded through a treating bath containing 20% of an approximately 50% solids aqueous solution of l,3-dimethyl0l-4,5-dihydroxyethylene urea and 2% of a 64% solids aqueous solution of magnesium chloride hexahydrate, was air dried and partially cured for 70 seconds at 110 C. Thereafter the fabric was creased by pressing and then cured 4 minutes at 340 F. The resulting cured, creased fabric had a crease retention of 5, an appearance rating of and an Accelerotor abrasion valve of 10.4% loss.

Example 4 Three treating baths were prepared as follows:

Treating Bath 1 contained Rhoplex B-; 1% Esbo 40, a 40% active epoxidized soyabean oil emulsion as an anti-stick agent; .15 of a nonionic wetting agent sold by Rohm & Haas Company under the trademark Triton X-IOO; and 0.1% of X-lSS, a wetting agent sold by Rohm & Haas Company.

Treating Bath 2 contained 15% Rhoplex B15; 1% Esbo 40; .15% Triton X-l00; and 0.1% X155.

Treating Bath 3 contained of an aqueous solution containing three parts by weight of an approximately 50% solids aqueous solution of 1,3-dimethylol-4,5-dihydroxyethylene urea and 2 parts by weight of a 40% solids aqueous solution of a polymethylated polymethylol melamine having an average of about four and one-half methoxymethyl groups and about one-half methylol group bonded to nitrogen; 3% of a solids aqueous emulsion of polyethylene; 1% of an acetic acid salt of a condensate of stearic acid and aminoethyl ethanolamine; 3% of a 64% solids aqueous solution of magnesium chloride hexahydrate; and 0.15% Triton X-100.

Fabrics A and B, all-cotton, regular weight, close weave twills, were padded as follows:

Fabric A was padded through Treating Bath 1 to an approximate wet pick-up of 60%. Fabric B was padded through Treating Bath 2 to an approximate wet pick-up of 60% and then both impregnated fabrics were padded through Treating Bath 3 to a 60% Wet pick-up. Thereafter both fabrics were calendered under 15 tons pressure and then dried and partially cured at 240 F. for 70 seconds. The resulting fabrics were creased, pressed and cured at 340 F. for 4 minutes.

Example 5 An all-cotton, regular weight, close weave twill was padded through a first treating bath containing 10% Rhoplex B-15; 10% Rhoplex K-3; 1% Esbo .2% X-l; and 0.15% Triton X-100 to an approximate wet pick-up of and then dried. Thereafter the fabric was padded through a second treating bath containing 24% of an approximately 50% solids aqueous solution of 1,3- dimethylol-4,S-dihydroxyethylene urea; 3% of a 25% solids aqueous emulsion of polyethylene; 3% of a 64% solids aqueous solution of magnesium chloride hexahydrate; 1% of an acetic acid salt of a condensate of stearic acid and aminoethyl ethanolamine; and 0.15% Triton X-l00 to a wet pick-up of about 60%. The thus impregnated fabric was then calendered under 15 tons pressure and dried and partially cured for seconds at 240 F. Thereafter it was creased by pressing and then finally cured for 4 minutes at 340 F. The resulting fabric had a crease retention and appearance rating after 2 home washes of 5 in each case and an Accelerotor abrasion percent loss of 167.

Example 6 Example 5 was repeated with the exception that 20% Rhoplex K3 was used in place of 10% Rhoplex B-l5 and 10% Rhoplex K-3. The resulting fabric had a crease retention and appearance rating after 3 home washes of 5 each and an Accelerotor abrasion per cent loss of 13.

An all-cotton, heavy weight, loose weave oxford was also treated in the same manner and had a crease retention and appearance rating after 3 home washes of 5 in each case and an Accelerotor abrasion per cent loss of 15.5.

Example 7 Example 8 A 15% aqueous solution of Rhoplex K-3 was padded on an all-cotton twill fabric at a 60% wet pick-up and dried. Then the impregnated fabric was padded with a second aqueous treating bath containing a 20% aqueous solution of the methylated 1,3-dimethylol-4,S-dihydroxyethylene urea prepared in the manner described in Example 7 and 3% of a 64% solids aqueous solution of magnesium chloride hexahydrate to a wet pickup of 60%. The fabric was then dried, partially cured at 235 F. for 70 seconds, then creased by pressing followed by a final cure of 4 minutes at 340 F. The resulting fabric, after machine washing and tumble drying, had an appearance rating of 5, a crease retention of 5 and an Accelerotor abrasion loss of 8.6% of its weight.

What is claimed is:

1. A method for manufacturing cellulosic textile fabrics capable of being formed into crease resistant textile articles having high abrasion resistance comprising (1) impregnating a cellulosic textile fabric with a yarnpenetrating aqueous solution of an acrylic polymer composed of about 49 to 50 weight percent polymerized ethyl acrylate, about 49 to 50 weight percent polymerized butyl acrylate and about 2 to 2.7 weight percent of methylol acrylamide to dispose on the fabric about 2.4 to about 6% acrylic polymer based on the weight of the cellulosic fibers in the fabric, (2) removing moisture there from, (3) thereafter impregnating the resulting fabric with an aqueous solution of a curable aminoplast resin-forming condensate, containing 1,3-dirnethy1ol-4,5-dihydroxy-2- imidazolidinone to dispose on the fabric about 3.0 to about 8 percent of said condensate based on the weight of cellulosic fibers in the fabric, and (4) thereafter drying the impregnated fabric.

2. The method claimed in claim 1 wherein the impregnated fabric resulting from step 3 is dried and substantially fully cured.

3. The method claimed in claim 1 wherein the impregnated fabric resulting from step 3 is dried and partially cured.

4. The method as claimed in claim 1 wherein the impregnated fabric resulting from step 3 is dried without substantial curing.

References Cited 60 UNITED STATES PATENTS 2,731,364 1/1956 Reibnitz et al. 117-64 2,764,573 9/1956 Reibnitz et al. 26067.5 2,987,421 6/ 1961 Sherwood.

5 3,116,967 1/1964 Goldstein et al. 1l7139.4 X 3,125,405 3/1964 Gardon 117139.4 X 3,220,869 12/1965 Ruemens et al. ll7139.4 X

WILLIAM D. MARTIN, Primary Examiner.

THEODORE G. DAVIS, Assistant Examiner.

US. Cl. X.R.

ll7l39.5, 143, 16], 138.8,