US 3323959 A
Description (OCR text may contain errors)
June 6, 1967 I A. KRECKL. 3,323,959-
METHOD OF MANUFACTURING INSULATING TEXTILE MATERIAL Filed Dec. 28, 1964 INVENTOR: ALOI S KR ECK L.
ATT'YS United States Patent s Claims. (ci. s- 155) This invention'relates to an insulating textile article and its method of manufacture. More particularly, the invention is directed to the fabrication of a multilayer insulating textile material composed of a sheet, band or blanket of voluminous fibrous fleece which is backed on both sides and which may be further provided with a waterproof covering or coating.
Multilayer Vinsulating sheets are known in which a foamed plastic is lined on either side with `a fabric. This covering of the foamed sheet mate-rial with fabrics is intended to provide a textile product which can 'be formed into articles of clothing or protective blankets such as various outer garments, sleeping `bags or the like. However, such articles are satisfactory only to the extent that they have the appearance of a textile fabric. As distinguished from true textile articles, such foamed plastic sheets backed with fabrics are relatively dense and stiff and do not bend or fold easily. As a result, this type of structure is useful as an insulating material only in very limited or special cases. In order to avoid stiffness in articles of clothing or the like, it is generally necessary to use very thin foamed plastic sheets, thereby substantially reducing any insulating effect. In most instances, it is necessary to greatly reduce the thickness of the foamed plastic or remove it entirely at those points where the insulating fabric must bend or where edges are sewed or stitched together. Attempts have been made to improve the softness and flexibility of the foamed plastic sheet, but the mechanical strength and the abrasion and resistance of the material is then reduced.
It is therefore much more desirable to Imake multilayer insulating textiles from la voluminous fibrous fleece which is quite flexible 'because it is easily compressed when folding or bending. However, unlike foamed plastic sheets, it is quite diflicult to attach a fabric lining or backing to both sides of the fibrous fleece except by stitching at least one of the fabrics to the fleece in a crosswise quilted pattern or along the borders of the two fabrics. A quilting type of stitch is particularly preferred in order to prevent the rather loosely joined and uniformly distributed fleece from shifting or bunching during use. Gne drawback of protective garments or sheet materials fabricated in this manner is that the large number of thin seams along the lines of stitching or quilting greatly reduce the heat retention capacity of the insulating fabric. Without such stitching, the "bunching or agglomeration of the fleece also tends to cause areas of low heat retention. A further disadvantage resides in the fact that water or moisture can penetrate through the stitching, even where the outer fabric is impregnated with a substance making it water repellent. Also, quilted fabrics do not lend themselves to the application of a separate waterproof coating.
It is further known that fiber fleeces can Vbe cemented or 'bonded into a relatively rigid and non-compressible structure which is not useful for textile insulating purposes because the fleece loses its flexibility and its capacity to be easily compressed and expanded. This technique of solidifying or bonding the fiber structure is normally used in making very compact and dense fiber felts or in making composite structures in which a network of fibers are bonded by an organic resin binding agent to forni an inflexible and solid three-dimensional article.
One object of the present invention is to provide a `multilayer insulating textile fabric containing a voluminous fibrous fleece which does not require stitching or quilting and which is readily adapted to be fabricated into many different types of protective garments or coverings.
Another object of the invention is to provide a fleece lined textile fabric which has improved insulating and moisture-proofing characteristics.
Still another o'bject of the invention is to provide a novel method of applying a cloth or fabric backing on both sides of a voluminous and readily compressible fibrous fleece so as to yield a unitary multilayer laminated structure having the essential flexibility and lightness required of an insulating textile.
Other objects and advantages of this invention will become more apparent from the following detailed specification.
It yhas now been found, in accordance with the present invention, that a highly satisfactory insulating textile material is provided by a voluminous fibrous fleece composed of two outer layers of bonded fleece fibers enclosing a core layer of non-bonded compressible fleece fibers, this core layer being substantially thicker than the outer layers, and a fabric backing adhered over each outer layer of the fleece. Either or both of the fabric backings can be made resistant to moisture or Water by applying a waterproof coating in the form of an additional outer layer or an impregnation of the fabric with any suitable waterrepellent or waterproof substance, e.g., rubber, neoprene or polyvinylchloride (PVC). In a preferred embodiment of the invention, the fibrous fleece is composed of .polyethylene terephthalate fibers and the cloth backing is composed of woven or knitted fabrics of nylon filaments or threads.
The method of manufacturing the insulating material of the invention essentially requires the steps of first bonding the fibers in the outer surface portions of a band of fleece While retaining an essentially non-bonded cornpressible fleece core between these outer portions, and then adhering a fabric onto each Iof the bonded outer surface portions of the fleece band. The fibers in the outer sur-face portions of the fleece can be readily bonded by means of a curable organic resin bonding agent so as to form a relatively rigid three-dimensional network or lattice. However, this bonding can also be accomplished by employing a fleece consisting of a mixture of fibers of different melting points, such that a rapid heat treatment of the outer surfaces of the fleece causes the lower melting fibers to soften or melt and then coalesce onto the higher melting fibers Where they touch lor overlap each other, thereby connecting the higher melting fibers into the desired network. These techniques of bonding fibers are generally Well known in the art and do not require any extensive explanation. The more rigid network of bonded fibers on either side of the fleece acts as a relatively stable base or framework for the adherence of the fabric backing, without depriving the entire fleece of its essential voluminosity and compressibility. Any suitable adhesive, preferably an adhesive which is resistant to Washing and dry cleaning, can then be applied to the fleece band and/ or to the fabric along the surfaces to lbe joined, the fabric and the fleece band being arranged in smooth juxtaposition, and the desired adherence between the fabric and fleece then being obtained by applying a uniform pressure to compress the fleece band against the fabric. Surprisingly, this method leads to a fabric backed fleece which is substantially free of wrinkles Without tearing the fleece apart or permitting it to shift or bunch together in the finished article.
' In the drawings:
YFiG. 1 is a schematic cross-sectional view of one embodiment of the multilayer insulating sheet material according to the invention, illustrating a fleece backed on either side by a fabric; and
FIG. 2 is a similar cross-sectional view of another embodiment in which the multilayer insulating sheet material is provided with a waterproof covering or coating on one side.
In FIG. 1, a voluminous fibrous fleece 1 consisting of natural or synthetic fibers or mixtures of such fibers has two outer surface layers 2 in which the bers are bonded together into a rigid or at least semi-rigid' structure :by`
means of any suitable organic resin bonding agent or other bonding means. Over these outer layers 2 by means of a continuous or discontinous film of an adhesive 3, there are adhered woven or knitted fabric backings 4 and 5.
The adhesive, which is preferably resistant to Washing and dry cleaning, can be sprayed or dipped in liquid form onto the outer surfaces of t-he fleece and/ or onto the inner surfaces of the fabricvbackings. Each fabric backing is then preferably adhered to the eece in separate or sequential steps in which one fabric is placed in smooth and even alignment with the rigidified or Ibonded outer surface layer of the fleece with the adhesive on adjoining surfaces. In order to ensure good contact and adhesion of the fabric to the fleece, the smooth sheet of fleece backed on one side with fabric should then be conducted through a calendar or similar means for applying uniform pressure on opposing surfaces of the sheet structure so that the fleece and fabric are compressed together. In order to cure or solidify the adhesive, the calendar rolls can be heated or else a self-curing adhesive composition can be employed. Such variations will be apparent to those skilled in this art.
The other fabric backing is then applied in exactlyY the same manner, e.g., in a second run through another set of calendar rolls after reversing the sheet so that the fabric is alwaysrapplied to the top surface of the fleece. If the adhesive is not immediately cured, it is advisable to collect or take up the fleece backed on both sides with vfabric on a winding reel having as large a diameter as possible in order to avoid wrinkling or creasing before the adhesive completely sets the fabric backings in place.
In FIG. 2, the multilayer sheet material has the same structure as in FIG. l except that an additional layer or coating 6 of a waterproof substance such as neoprene or PVC has been applied to the top or outer fabric layer. This waterproof coating can also be applied to the other fabric, representing the inner surface of the sheet, e.g., where the insulating sheet is to be employed in diving suits or the like. The fabric can be impregnated with a waterrepellent substance before or after attaching the fabric to the fleece, or else a thin layer or sheet of a solid waterimpervious elastomeric substance can be adhered to the fabric backed fleece. Y
During the application of the fabric backings to the fleece, there may be sufficient compression to partly crush or break down the network of bonded fibers in the outer surface layers 2 surrounding the non-bonded and compressible core of the fleece 1. This is not harmful since the outer layer of bonded fibers primarily serves to hold the fabric in a smooth surface condition which is free of Wrinkles, creases or folds during the initial application of the fabric up to a point where there is a relatively firm adhesion between the fabric and the fleece. Thereafter, it is not necessary for the bonded bers to provide the same degree of rigidity, and an increased capacity to be compressed or folded is even desirable in the finished insulating textile.
As will be readily understood, the exact dimensions of the various layers of fleece, fabric backings and any waterproof coating will depend on numerous factors, including the particular fibers being employed in the fleece and fabric as well as the voluminosity, bulk density, insulating capacity and other properties desired in the finished product. However, for use as a textile product,
the finished insulating sheet should have a fleece withthe compressible core being as thick as possible and the outer layer of bonded fibers being as thin as possible in order to achieve maximum flexibility. In general, the core should represent at least 60% of the total thickness of the fleece and in most applications should be or more. It is especially preferred to have a structure in which each outer layer of bonded fibers amounts to no more than approximately 5% of the total thickness of the fleece. The outer layer of bonded fibers need only be of suflicient depth or thickness to provide a substantially smooth and flat surface capable of supportinga smooth wrinkle-free piece of fabric during adhesion of the fabric to the fleece.
Wool, nylon and/or polyester fibers, and particularly polyethylene terephthalate fibers are especially useful as a voluminous fleece material, although other fibers such as polyacrylonitrile, polyvinyl chloride and the like are Yalso feasible. The physical characteristics of these bers can vary over a wide range. For example, it is possible to use fibers having a denier of about 1 to 25, a lament length in the range of approximately 10 to 100 mm., and crimping-are numbers on the order of 20 to 250 arcs/ l0 cm. or more. More specifically, polyethylene terephthalate or similar preferred polyester fibers can be employed with a titer of at least 3 denier/ 30 mm. up to about 9 denier/ 60 mm. and crimping-arc numbers of about 50 to 200 arcs/ 10 cm.
Mixtures of different fibers can also be employed in the fleece, and special bonding fibers having a low melting point are especially useful in such mixtures so that the outer surface layers of the fleece can be subjected to a thermal treatment sufiicient to melt these bonding fibers which then act as the bonding agent forV the remaining fibers having a normally higher melting point. Thus, it is possible to use known polyester fibers, e.g., modified polyethylene terephthalate fibers, having a melting point of about l65 and to expose the outer surfaces of the fleece to such temperatures by means of infrared radiation or contact with heated rolls.
The fibers in the outer surface layer of the fleece are bonded or glued to each other by incorporating any suitable bonding agent into that surface portion of the fleece which must be at least partly solidified for the purposes of the invention. While solid bonding agents such as the above-noted bonding fibers or similar solid glues or adhesives can be brought into the surface of the fleece and then melted and fused by subsequent heat-treatment, it is preferable to employ one of the many known organic resin bonding agents which can be readily dispersed in water or some other liquid or solvent system. This organic resin bonding agent can then be spray coated onto the surface of the fleece or the fleece can be dipped for a short distance into a liquid containing the bonding agent, thereby permitting a more accurate and uniformly controlled depth of impregnation.
There isa wide range of organic resinous materials, other than bonding fibers, which can be selected as a bonding agent for producing the cohesive outer surface layer of the |fleece. The primary object is to achieve a sandwich structure of the fleece in which the voluminous compressible core of eece fibers is enclosedrby two thin, stiff and relatively porous outer layers of the fleece fibers. In other words, these outer layers should not be fully impregnated and formed into a continuously solid mass, but instead the bonding agent should be applied in an amount suflicient to join the individual fibers to each other at their points of intersection in the fleece network. Therefore, it is advisable to employ a resinous material which can be cured or set by heat and/ or a catalyst after application to the outer layers of the fleece, so that the fibers are bonded rigidly to each other in an open or porous three-dimensional structure of ilbers corresponding substantially to the position of the same bers in the normal non-bonded fleece.
Suitable thermosetting or curable organic resins for use as the bonding agent include those which can be applied to the fleece in liquid form, especially those resins which are easily emulsied or dispersed in Water so as to be sprayed onto the surface of the fleece. Especially good results have been achieved with aqueous spraying compositions which provide cross-linkable polyacrylic acid or polymethacrylic acid derivatives as the bonding agent for the outer layers of fleece fibers, especially where resistance to washing and dry cleaning is a necessary factor to be considered. These resins can be sprayed onto the surface of the fleece in the form of an aqueous emulsion to a predetermined depth, preferably not more than about 5% of the thickness of the fleece band, and then cured at temperatures of about 80 C. to 130 C. in the presence of a catalyst such as the usual peroxide cross-linking catalysts, e.g., benzoyl peroxide.
Other suitable thermosetting or curable organic resins include unsaturated polyester or alkyd resins, self-curing epoxy resins, or aminoplasts such as urea-formaldehyde, phenol-formaldehyde and the like. However, many such resins are excluded for purposes of this invention because they are not resistant to washing Vand dry cleaning or because they tend to form a rigid layer of the resin itself in the form of an impregnated binder rather than an open or porous network of bonded fibers.
Among those resins suitable as bonding agents for producing the outer surface layer of the eece the amide of the polymethacrylic acid is especially useful. It is to be had in the trade under the trade names Plex 4673D and Plex 4653D (Rhm and Haas) and corresponds to the following formula: v
This compound has still some free carboxy groups and is interlaced with about 1% ammonium chloride at temperatures over 80 C. forming imide-bridges.
Good results in the process of curing the outer surface layers of the fleece are likewise obtained when the amide vof the polyacrylic acid is interlaced together with a urea formaldehyde resin in the presence of ammonium chloride.
Bonding agents of this kind when used to cure the outer layers of the eece have proved to be especially resistant to solvents.
The fibers with a low melting point used to solidify the outer layers of the fleece are preferably made of polyesters with a low melting point which are produced by mixing terephthalic acid with an aliphatic di-carbonic acid e.g., adipic acid and then polymerizing with ethylene glycol. The melting point of the copolymer is variable in wide ranges (see `W. H. Carothers and I W. Hill, l. Amer. Chem. Soc., 54
(1932), 1559, 1579, U.s. Pat. 2,130,958. R. Hill and E. E. Walker, I. Polymer Sci., 3 (1948),.609. E. F. Izard, J. Polymer Sci., 9 (1952), 35. H. Batzer and G. Fritz, Makromolekulare Chem., 14 (1954), 179-232. H. Batzer, Makromolekulare Chem., (1953), 1.3-29.)
. Any suitable fabric can be adhered to the fleece band as a backing on both sides of the fleece, and it is particularly advantageous to use a nylon fabric which may be further coated with a waterproof substance. Thus, wool or polyester fiber fleeces backed on both sides with a knitted fabric of polyamide (nylon) threads are particularly suitable for use as a sleeping blanket or in sleeping bags, in contrast to the known plush or tufted blankets in which the exposed fiber pile is easily soiled or through so-called pilling loses its open texture and thereby its insulating effect. In making diving suits, sea rescue suits or similar garments for underwater work, it is advantageous to ernploy polyester lleeces backed on both sides with a nylon fabric, each backing being further coated with neoprene or PVC. Finally, polyester eeces backed on one side with a nylon fabric having an exposed velour surface and on the other side with a nylon fabric which may also be waterproofed are adapted to be used in manufacturing light- Weight Winter clothing having a high Wearing comfort. Multiple layers of fabrics or other backing materials such as rubber sheets, glass fiber fabrics, foils and the like can be adhered without difllculty to the initial fabric backing in order to achieve special effects.
In all cases, it is advisable to employ fabrics or other backin-gs on opposite sides of the fleece so that the stretch value of the two opposed or paired backings is substantially the same. Otherwise, there is tendency of one or the other of the backings to wrinkle or form creases.
A wide variety of known adhesives are available for the purpose of firmly connecting one or more fabric or other backings onto the bonded outer layerV of the fiber fleece. Isocyanate adhesives are especially useful because of their resistance to washing and dry cleaning. Also, it is advantageous to employ the so-called elastomeric adhesives so that the fabric backing retains its stretch value or elasticity after being adhered to the fleece. Suitable diisocyanate adhesives, commonly used for adhesion of natural or synthetic rubber to fibers, are disclosed in standard references such as Polyurethanes, by B. A. Dombrow, Reinhold Publishing Corp., New York (1957), chapter 7.
Isocyanate based adhesives are suitable for firmly connecting the fleece to a textile fabric as well as the textile fabrics to waterproof layers made of, eg., polyvinyl-chlo ride or rubber.
To cover the fleece the outer layers of which have been cured with textile fabrics the amides of the polyacrylic acid or of the polymethacrylic acid can be used if they are applied as a paste. Generally, they have the following formula In covering the said lleeces with textile fabrics the same methods can be applied which are used for covering foam products (see `H. Bergs, W. Blume and W. Heiderhoff, Textilindustrie,
E. Rickenbacher, SVF-Fachorgan, 18 (1963), No. 3, 157- O. Glenz, F. Kassack and G. Berndt, Melliand-43,
A. Grom, Zeitschrift fr die gesamte Textilindustrie,
64 (1962), vol. 2, 77-84).
The invention is further illustrated by the following examples of multilayer insulating materials having specie applications.
Example 1 A polyester ilber fleece composed of 6 denier fibers with a staple length of 40 mm. and having a weight of about grams/m.2 was joined on both sides by means of ad adhesive resistant to washing and dry cleaning with a knitted nylon fabric. The upper or outer side of the fleece was backed with a voluminous velour on the exposed surface of the fabric, as produced by the usual velouring process from a warp knitted fabric in the familiar types of nap patterns of 40/ 10 or 60/12 denier nylon threads. In this velouring process, the individual filaments are not torn up or cut but merely raised. On the under or inner side of the fleece, there was applied a smooth warp knit fabric of and 3() denier nylon threads, 'the fabric having a weight of about 40-50 gram/m.2 and a pattern yielding the same stretch or expension values as the velour fabric on the opposite side of the fleece. Regardless of whether the velour denierV was 40/ 10 or 60/ 12 denier, the smooth surface of the velour knitted fabric consisted of threads which were not stronger than 40 denier.
An insulating sheet material produced in this manner from the polyester fleece (polyethylene terephthalate fibers) backed on both sides with nylon knitted fabrics has a total Weight of 307 grams/m.2 and a thermal efficiency of 71%. The insulating capacity was tested as follows:
Testing temperature C-- 63 Room temperature C-- 23 Heat gradient C 40 Wind velocity m./sec 3.4 Consumption kcal./hr.m.2- 281 Saving kcal./hr.m.2 677 Thermal efliciency percent 71 This result is clearly superior to other comparable insulating materials, e.g., it was found that Ya polyester eece quilt stitched with nylon knitted fabrics and weighing 3,60 grams/m.2 had a thermal efciency of 65%, and the same polyester fleece stitched tov backings of a polyacrylonitrile plush fabric and weighing 380 grams/m.2 had a thermal etliciency of 67%. y
The excellent heat-retention capacityand low weight of the insulating fabric of this example make it ideally suited as a lining for cold weather clothing such as all types of coats, jackets and the like used in outdoor activities.
Example 2 In other embodiments of the polyester fleece backed `on both sides, the same fleece as in the preceding example was backed on one side with the same veloured nylon fabric but on the other side with various fabrics consisting of natural or synthetic woven fabrics, including lightweight nylon fabrics with a linen weave and fabrics which are further coated or impregnated with a waterproof -or water-repellant substance, this other side forming the outer portion of the multilayer fabric away from the body being protected. This combination provides a single or unitary insulating fabric with a knitted velour lining and outer protective fabric and offers an advantage in tailoring in that it can be cut in one piece and sewed together. It is thus adapted to be easily manu- Y factured into lightweight winter clothing such as coats,
jackets, ski or skating pants, anoraks and the like.
Example 3 A polyester fleece composed of polyethylene terephtha-late bers of 6 denier and 40 mm. staple length `and having a weight of about 200 grams/m.2 was adhered on both sides to a nylon fabric by means of an adhesive resistant to washing and dry cleaning. The nylon fabric corresponding to the outer side of a protective garment was further coated with a polyvinyl chloride so as to be completely watertight. This outer nylon fabric consisted of a high-strength nylon fabric of 210/36 denier threads with a card setting of the threads of 18/ 18. The weight of this fabric was about 100 grams/ m.2 (uncoated) and it had a breaking strength in warp and weft of at least 100 kg.
, The inner liningor fabric next to the body being protected consisted of a nylon fabric composed of 60 denier threads in both warp and weft and had la weight of about 60 grams/m.2. This fabric was coated on the inner exposed surface with 20-30 grams/m.2 of a polyvinyl chloride so as also to be waterproof.
The coating of the fabrics can-also be accomplished with a'synthetic rubber sheet such as neoprene In this case, it is necessary to use one of the known adhesives having good adhesion for rubber as well as the nylon fabric. In Vthe case of the PVC coating, e.g. as would be used in sea diving suits or the like, the PVC coating composition should be selected for `its resistance to heat, cold, abrasion, seawater and oils or other chemicals as well as such properties as color trueness and fastness and weldability in making seamless suits.
An insulating material of this type has high strength, is watertight on both sides, and has a relatively low Weight of about 650 grams/m.2. It also exhibits a high capacity for heat retention: for example, a glass flask filled with lwater at about 44 C. and enclosed by this material can be placed in flowing water of 16 C., and the temperature of the water in the flask then drops slowly as an approximately linear function of time to about 32 C. after four hours.
By means of this adherent fabric backing on both sides of the fleece, whether permeable to air or moisture or coated so as to be watertight, the inner core of fleece functions to provide the desired insulating effect. Furthermore this is accomplished without losing the essential flexibility, voluminosity and lightness of weight required in satisfactory protective garments or blankets. The thermal efficiency of the multilayer insulating textile materials of the invention is not substantially reduced by the penetration or collection of water, dirt or other contaminants, and there is no disturbance of the uniform distribution of the fleece. The manner in which the fabric backings are adhered to the fleece Vprevents the formation of wrinkles or creases so as to give a high quality product suitable for the manufacture of clothing or other textile products having a smooth and even texture on both sides of the multilayer fabric. At the same time, the unitary bondedwand adhered structure of the multilayer fabric permits rapid cutting and piecing together of a Wide Va- Vrity of textile insulating garments or protective coverings.
In the above examples, the polyester fleece was first sprayed on one side with an aqueous emulsion of a polymethacrylic resin identified as an amide of polymethacrylic acid in an amount sufficient to bond the'bers after heating at about C. to la depth of about 5% of the total thickness of the fleece. This same procedure was then repeated on the other side of the fleece to provide two outer bonded layers of fibers on which the Vfabrics were adhered, first on one side and then on the other side. The adhesive used in applying the fabrics was a paste consisting of an amide of polymethacrylic acid.
The invention is claimed as follows:
1. A method of manufacturing an insulating textile material composed of a synthetic thermoplastic fibrous fleece band backed on either side by a textile fabric, which method comprises: applying an emulsion of a vcrosslinkable thermosetting organic resin bonding agent to the fibers solely in both outer surface portions of said lieece band without fully impregnating the porous structure of said outer portions; cross-linking said resin to bond the fibers at their points of intersection in said outer portions while retaining an essentially non-bonded cornpressible fleece core between said outer portions, said core being substantially thicker than said outer portions; adhering a fabric onto one of the bonded outer portions of said fleece band; and subsequently adhering another fabric onto the other of said bonded outer portions of said fleece band.
2. A method as claimed in claim l-wherein each fabric is adhered to the fleece band by applying an adhesive to at least one of the surfaces to be joined, arranging the fabric and fleece band in smooth juxtaposition, and applying uniform pressure to compress the fieece band against the fabric.
9 3. A method as claimed in claim 2 wherein Iche stretch Value of each fabric backing is substantially the same.
References Cited UNITED STATES PATENTS 1,458,008 l6/1923 Sexton ll-82 2,164,499 7/ 1'939 Coughlin 161-82 2,619,705 12/1952 Foster 16'1--90 10 2,689,199 9/1954 Pesce -161-72 3,081,917 3/1963 Driesch 5 343 X OTHER REFERENCES Linton: The Modern Textile Dictionary, Duell, Sloan and Pearce, N.Y., 1963, p. 991 relied on.
ALEXANDER WYMAN, Primary Examiner.
G. D. MORRIS, Assistant Examiner.
UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No 3 ,323 ,959 June 6 1967 Alois Kreckl It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column l, line 40, strike out "and"; column 5, line 6l,
for "2,130,958" read 2,130,948 column 6, line 68, for "ad" read an column 7, line 6, for "pension" read pansion Signed and sealed this 26th day of November 1968.
EDWARD J. BRENNER Edward M. Fletcher, Jr.
Commissioner of Patents Attesting Officer