US3846158A

US3846158A - Flushable,pre-moistened wipers

Info

Publication number: US3846158A
Application number: US00263145A
Authority: US
Inventors: K Vasilyadis
Original assignee: Scott Paper Co
Current assignee: Kimberly Clark Tissue Co
Priority date: 1972-06-15
Filing date: 1972-06-15
Publication date: 1974-11-05
Anticipated expiration: 1991-11-05

Abstract

1. A FLUSHABLE, PRE-MOISTENED WIPER CAPABLE OF BEINB PACKAGED IN A WET CONDITION FOR A LONG PERIOD OF TIME WITHOUT DISINTEGRATING, SAID WIPER COMPRISING: A. A WEB OF SOFT, FLEXIBLE, ABSORBENT FIBROUS MATERIAL HAVING OPPOSED MAJOR SURFACES, SAID WEB INCLUDING A FIBER WEIGHT OF AT LEAST 50% OF SHORT CELLULOSIC FIBERS OF A PAPERMAKING LENGTH LESS THAN 1/4 INCH; B. TWO WATER-INSOLUBLE ADHESIVE DISTRIBUTIONS ASSOCIATED WITH SAID WEB; (1) ONE WATER-INSOLUBLE ADHESIVE DISTRIBUTION BEING DISTTIBUTED OVER ONE MAJOR SURFACE OF THE WEB IN A PATTERN OF DISCRETE ISLANDS SEPARATED BY CORRIDOR REGIONS, SAID ISLANDS COVERING MORE THAN 50 PERCENT OF THE SURFACE AREA OF SAID WEB AND EXTENDING AT LEAST PARTIALLY THROUGH THE THICKNESS OF THE WEB FOR ENHANCING THE WETTENSILE STRENGTH OF SAID WEB TO PERMIT USE OF SAID WEB IN A WET CONDITION WITHOUT MECHANICAL DISINTEGRATION AND FOR AIDING IN STABILIZING SURFACE FIBERS OF SAID WEB, SAID WEB MECANICALLY DISINTEGRATING SUBSTANTIALLY IN SAID CORRIDOR REGIONS WHEN FLUSHED WITHIN THE VORTEX OF A CONVENTIONAL HOUSEHOLD TOILET SYSTEM; AND FING-01 (2) THE OTHER WATER-INSOLUBLE ADHESIVE DISTRIBUTION DISPOSED UNIFORMLY OVER THE PLANAR EXTENT OF THE WEB AND ASSOCIATED WITH AT LEAST THE OTHER MAJOR SURFACE OF SAID WEB WHICH IS OPPOSED TO SAID ONE MAJOR SURFACE, SAID OTHER WATER-INSOLUBLE DISTRIBUTION EXTENDING AT LEAST PARTIALLY THROUGH THE THICKNESS OF SAID WEB AND HAVING A SOLUBLE DISTRIBUTION EXTENDING AT LEAST PARTIALLY DRY WEIGHT OF THE FIBERS IN SAID WEB; WHEREBY SAID OTHER ADHESIVE DISTRIBUTION AIDS IN PROVIDING STRUCTURAL INTEGRITY TO SAID WEB DURING USE, PERMITS MECHANICAL DISTINTEGRATION OF THE WEB ONCE SAID WEB IS SUBJECTED TO MECHANICAL AGITATION OF THE TYPE ENCOUNTERED IN CONVENTIONAL HOUSEHOLD TOILET SYSTEMS, AND STABILIZES THE FIBERS ON AT LEAST SAID OTHER MAJOR SURFACE OF SAID WEB TO ENHANCE THE ABRASION RESISTANCE OF SAID OTHER NAJOR SURFACE; AND C. A MOISTURE CONTENT IN SAID WEB OF FROM BETWEEN ABOUT 100% AND ABOUT 350% BY WEIGHT BASED ON THE DRY WEIGHT OF THE FINISHED WEB.

Description

Nov 5, 1974 K. o. VASILYADIS FLUSHABLE PRE-MOISTENED WIPERS Filed June 15 1972 United States Patent Office 3,846,158 Patented Nov. 5, 1974 3,846,158 FLUSHABLE, PRE-MOISTENED WIPERS Kosta 0. Vasilyadis, Newark, Del., assignor to Scott Paper Company Filed June 15, 1972, Ser. No. 263,145 Int. Cl. B05c 9/04 US. Cl. 117-685 11 Claims ABSTRACT OF THE DISCLOSURE Flushable, pre-moistened wipers include an adhesively bonded web of soft, flexible, absorbent fibrous material having a moisture content of from between about 100% and about 350% by weight based on the dry weight of the finished web, and a fiber composition comprising at least 50% by weight of short cellulosic fibers of a papermaking length less than one-quarter inch. A first waterinsoluble adhesive distribution is substantially uniformly distributed over the planar extent of the web and at least partially through the thickness of the web for enhancing the abrasion resistance of at least one surface of the web; for providing structural integrity to the web for long periods of time in its pre-moistened condition and for permitting mechanical disintegration of the web when the web is subjected to mechanical agitation of the type encountered within the vortex of a conventional household toilet system. A second water-insoluble adhesive distribution is disposed in the web in a pattern of discrete islands to form bonded web regions which are not substantially mechanically disintegratable upon the application of forces thereto of the type encountered within the vortex of a conventional household toilet system. These islands cover more than 50% of the surface area of the web and extend at least partially through the thickness of the web for enhancing the wet-tensile strength of the web and for aiding in stabilizing surface fibers of the web. The islands are separated by corridor regions along which the web mechanically breaks up under mechanical forces of the type encountered within the vortex of a conventional toilet system. I

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to fiushable, pre-moistened wipers.

Description of the Prior Art Pre-moistened wipers are extremely popular for cleansing many portions of the human body. For example, such wipers have provided the means for cleansing parts of the human body under conditions where water, towels, and the like are not available. One specific use for premoistened wipers is for cleansing excreta from the human anus, and usually after toilet paper has been used in the normal manner. In such an application, the wiper is not a substitute for toilet paper, but provides the final cleansing operation after the bulk of the excreta has been re moved in the usual manner.

Pre-moistened wipers have many other applications. For example, they can be used to cleanse parts of the body other than the anus, such as under the arms, face and/or neck.

A long period of time, i.e. one-half to two years, often elapses from the time of manufacture of pre-moistened wipers until the time of use. Therefore, to remain functional, the pre-moistened wipers must have sufficient structural integrity for their intended wiping function after such a long period of time. In addition, flushability of the wiper is an extremely desirable property, especially when the pre-moistened wiper is intended for use as an anal wipe as part of the normal cleansing function after a bowel movement.

Prior art pre-moistened wipers have included large percentages (i.e. 1%. to 4%) of a wet strength resin, such as melamine resin. Such wipers usually have such a high wet strength that they will not disintegrate or break up into small fiber clumps when flushed within the vortex of a conventional household toilet system. Therefore, such pre-moistened wipers, if consistently flushed, will tend to plug the drainage systems associated with such toilet systems. Also wipers including a large percentage of wet strength resin tend to be somewhat harsh and inflexible, and therefore, such wipers are not the most suited for use in wiping sensitive parts of the human body. Prior art wet wipers of the type described above are disclosed in US. Pat. Nos. 3,129,811 and 3,057,467 issued to Willinms; and 2,840,080, issued to Clark.

Prior art nonwoven fabrics have relied upon chemical disintegration, or breakdown of either the fibers in the web or an adhesive component in the web in order to achieve flushability. US Pat. Nos. 3,554,788; 3,561,447 and 3,616,797 disclose nonwoven fabrics bonded with an adhesive having a water-soluble component which is dissolved when exposed to excessive moisture. US. Pat. No. 3,521,638 discloses a fabric which includes a chemically modified cellulosic fiber which is water sensitive to dis integrate when exposed to excessive moisture. US. Pat. No. 3,536,563 relates to a laminated product which includes a water-soluble film disposed between opposed layer of crepe paper wadding. The film will disintegrate when exposed to excessive moisture. All of the above fabrics are packaged in a dry condition, and allegedly will retain their structural integrity for a short period of time after use. The above fabrics will not retain sufiicient structural integrity for the long periods of time required of wet wipers when such fabrics include a moisture content of from between about to about 350% by weight based on the dry weight of fibers in the web.

SUMMARY OF THE INVENTION Reference throughout this application to the dry Weigh of fibers and webs refers to the weight of the fibers and webs under equilibrium conditions in an environment of 50% relative humidity and 6870 F.

This invention relates to fiushable, pro-moistened wipers which have sufiicient wet strength for their intended wiping function for a long period of time, i.e. one-half to two years, and yet are fiushable within a conventional household toilet system. The Wiper is an adhesively bonded web of soft, flexible absorbent fibrous material. The fibrous material includes short cellulosic fibers of a papermaking length less than one-quarter inch having a dry weight constituting over 50% of the dry Weight of the fibrous material within the web.

The web has a moisture content of from between about 100% and about 350% by weight based on the dry weight of the finished web. The web includes first and second water-insoluble adhesive distributions therein. The first adhesive distribution is present in an amount of no more than about 5% by weight solids based on the dry weight of fibers in the web; and is distributed substantially uniformly over the planar extent of the web and at least partially through the thickness of the web. This first adhesive distribution permits mechanical disintegration of the web when the web is subjected to mechanical agitation of the type encountered within the vortex of conventional household toilet systems. In addition, the first adhesive distribution stabilizes the fibers of at least one surface of the web to enhance the abrasion resistance of said surface, and aids in maintaining structural integrity of the web for long periods of time in the presence of the moisture content within the web. In the preferred embodiments of this invention the first adhesive distribution is substantially continuous over the planar extent of the web and is achieved by either wet-end bonding in a wet web formation process, or by spraying the web after formation.

The second water-insoluble adhesive distribution is in a pattern of discrete islands to form bonded web regions which are not substantially mechanically disintegratable when agitated within the vortex of a conventional household toilet system. These islands cover more than 50% of the surface area of the web for stabilizing surface fibers of the web and for enhancing the wet strength of the web to permit its use in a wet condition without mechanically disintegrating. The web will mechanically disintegrate along corridor regions separating the islands when the web is subjected to mechanical agitation of the type encountered within a conventional household toilet system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a flushable, pre-moistened diaper with a part broken away to show details of adhesive distribution;

FIG. 2 is a sectional view along line 22 of FIG. 1;

FIG. 3 is a sectional view along line 22 of FIG. 1 showing an alternative embodiment of the invention; and

.FIG. 4 is an enlarged view of the blocked portion of FIG. 1 which is identified as 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring to FIGS. 1 and 2, a fiushable, pro-moistened wiper 10 according to a first embodiment of this invention includes a fibrous web 12 having a first water-insoluble adhesive distribution 14 disposed substantially uniformly and continuously throughout the web, and a second waterinsoluble adhesive distribution in the form of discrete islands 16. The discrete islands 16 are not substantially mechanically disintegratable upon the application of forces thereto of the type encountered within the vortex of conventional household toilet systems. The islands 16 are separated by corridor regions 18 which are mechanically disintegratable upon the application of such forces thereto. The fibrous web 12 has a minimum moisture content therein to permit moisture to drip therefrom when the web is subjected to crushing or crinkling forces; and a maximum moisture content equivalent to all the moisture the web will hold without dripping under the infiuence of gravitational force. A moisture content of from between about 100% and about 350% by weight based on the dry weight of the finished web normally meets the above requirements. In the most preferred embodiments of this invention, the moisture content is maintained in the range of from between about 175% and about 250%. This latter moisture content range is perceived to be most acceptable to the tactile sense of a user.

The fibrous web 12 includes at least 50% by weight of short cellulosic fibers of a papermaking length less than one-quarter inch, such as wood pulp fibers and cotton linters. These short fibers are preferred because they are inexpensive, readily available and highly absorbent. If desired, the web 12 can be formed from 100% of such short fibers; however, some reinforcing fibers having an average fiber length of one-quarter inch or longer can be utilized to enhance the softness and strength of the web. Exemplary reinforcing fibers are rayon, cotton, polyester, polyamide, polyamine, etc. A typical fibrous web according to this invention has from between about 75% and about 90% by weight of lignocellulosic short fibers, and from between about 10% and about 25% by weight of longer reinforcing fibers.

The first water-insoluble adhesive distribution 14 in this first embodiment of the invention is effected by wet end addition of said adhesive in papermaking-type equipment, i.e. in the fiber furnish prior to said furnish being directed onto a drainage member for forming the fibrous web 12. In this manner, the first adhesive distribution 14 is substantially uniformly and continuously distributed throughout the web 12 (FIG. 2). The amount of adhesive added to the wet end is chosen such that the formed web has from between about .75 and about 4% solids weight based on the dry weight of fibers in the web. Below .75 the product is too weak to perform its normal wiping function, and tends to break up along the corridor regions during use. Above 4% solids weight the fibrous web will not break up, or disintegrate, in a sufficiently short period of time when flushed within a conventional household toilet system. Most acceptable results have been achieved with a first adhesive distribution not exceeding 3% solids weight based on the dry weight of the fibers in the web.

The second water-insoluble adhesive distribution, in the form of discrete islands 16, in this first embodiment of the invention, is effected by a print bonding operation (e.g. gravure printing). The discrete islands 16 must cover more than 50% of the surface area of the web to prevent pilling (fiber separation) on the surface during use. Preferably, the discrete islands 16 cover more than of the surface area of the web. The adhesive defining the island 16 is present in an amount of up to about 8% solids weight based on the dry Weight of fibers in the web. The addition of 8% adhesive renders the product somewhat harsh, and 6% is a more preferred upper limit. In adidtion to preventing .pilling of the surface, the waterinsoluble discrete islands 16 define bonded regions which enhance the wet tensile strength of the product to insure that its structural integrity is maintained during its use in wiping. The permissible upper limit of adhesive solids in islands 16 is dictated primarily by the softness requirements of the web.

The cross-machine direction wet tensile strength of the wiper 10 is maintained at over 3.5 ounces per inch, and preferably over 4.0 ounces per inch. The tensile strength is determined by gripping a 1" wide sample with opposed jaws of Instron Tensile Tester, Model No. 2128. The starting jaw span is 2 inches, and therefore, the dimension of the sample in the test direction is greater than 2 inches to permit gripping of the sample. The jaws are separated at a speed of 2 inches/minute until the sample breaks and the maximum force applied to the sample is recorded as the tensile strength.

As stated above, the adhesive defining the islands 16 is of an amount which does not permit substantial mechanical disintegration in the islands. Therefore, the dimensions of the islands must be sufiiciently small to permit them to be received within drainage systems without plugging such drainage systems when the web breaks up along the corridor regions 18. In the preferred embodiment of this invention, each island 16 is square, and is no greater than one square inch in area. Islands of other geometric configurations can be utilized, the particular configuration not constituting a limitation on the invention.

The spacing between discrete islands 16 to define the corridor regions 18 is chosen to permit the web to break up along the corridor regions when the web 12 is subjected to mechanical forces of the type encountered in a conventional household toilet system. This spacing will vary depending upon the length and orientation of the fibers utilized in the web. The spacing between islands is chosen such that a substantial number of fibers disposed in the corridors 18 will not bridge the corridors to be bonded by adjacent islands. In this manner, the corridor regions 18 remain sufiiciently weak (i.e. retaining the structural integrity imparted to the web by the first adhesive distribution 14) to permit the fibrous web 12 to mechanically break up along the corridor regions under mechanical forces of the type encountered within the vortex of conventional household toilet systems.

Referring to FIG. 4, the discrete islands 16 include regions 20, in the form of sub-corridors which are free of the adhesive defining said islands. These sub-corridors permit the moisturizing ingredient to penetrate through the surface of the web in the island regions to permit transfer of such ingredient from the web to the area being wiped. The dimensions of sub-corridors are dictated by the lengths and orientation of the fibers in the web to assure that most of the fibers within the confines of the islands 16 are bonded by the water-insoluble adhesive defining said islands. In the wet wiper the dimensions of the sub-corridors between adjacent sub-islands 21 is from between about 3 mils and 8 mils.

The configuration of the regions 20 within each island that is free of the second adhesive distribution is not critical. For example, the regions 20 could be in the form of discrete islands, as opposed to continuous corridors. However, the dimensions of the regions 20 must be such as to insure that most of the fibers within the confines of the islands 16 are bonded by the adhesive defining said islands.

Reference in this application to the percent of the surface area covered by the islands 16 neglects the presence of regions 20 within each island which do not include the adhesive defining each of said islands. These regions 20 are neglected because they are dimensioned to assure bonding of most of the fibers within the islands by the adhesive defining said islands, and therefore, do not adversely effect the abrasion resistance and/ or the stability of the web.

The moisturizing ingredient in the fibrous web includes a major proportion of water, and other ingredients which are not limiting on the present invention. For example, such other ingredients can include alcohol, glycerine, propylene glycol, lanolin, fungicides, bacteriocides, bacteriostats, etc.

The water-insoluble adhesives utilized in this invention are high polymers which are not hydrolyzable in the wet wiper environment. The adhesive in the first distribution 14 must be of a type which will permit mechanical disintegration of the web when the web is subjected to mechanical forces of the type encountered in conventional toilet systems. Latices are the preferred water-insoluble adhesives utilized in both

adhesive distributions

14 and 16 since they are elastomeric, and impart soft flexible properties to the web. Preferably, the acrylic latices are utilized, and these are commercially available from many sources. For example, acrylic latices supplied by Rohm & Haas under the trademarks HA-8, E- 485 and P-339 have been utilized successfully in the wet wipers 10 of this invention. The adhesive in the first and

second distributions

14 and 16 can be the same or different.

Other water-insoluble adhesives can be utilized in the nonwoven wipers of this invention, and such adhesives are well known to those skilled in the art. For example, the water-insoluble adhesives disclosed in US. Pat. No. 3,616,797, referred to earlier in this application, can be utilized.

Referring to FIG. 3, a second embodiment of a wet wiper 10A has a first water-insoluble adhesive distribution 14A which is formed by spraying a water-insoluble adhesive on one surface of a formed fibrous web 12A. According to this bonding technique, the solids weight of the latex in the first adhesive distribution in the web is maintained from between about 2% and about 5% by weight based on the dry weight of fibers in the web. When the first adhesive distribution 14A is effected by spraying, a heavier adhesive concentration exists on the surface of the web, than in interior portions thereof, and the concentration of adhesive gradually decreases with increased de th of penetration. In all other respects, the second embodiment is identical to the first.

The solids weight range of the first adhesive distribution in wiper 10A, which is achieved by spraying, overlaps the solids weight range in wiper 10, which is achieved by wet end bonding and has a higher minimum and maximum value than the solids weight range achieved by wet end bonding. This higher minimum and maximum value assures that the adhesive sutficiently penetrates into the interior of the web to sustain the structural integrity of the web during use.

If desired, the wet wipers of this invention can be creped, embossed or otherwise texturized to enhance softness of the product. Normally, working the Web to enhance its softness tends to reduce the wet tensile strength of the web. Therefore, the conditions of forming the web; such as curing time and temperature, amount of adhesive, fiber composition and print bonding pattern must be controlled such that the wet tensile strength in the web is maintained at a sufiiciently high level to withstand usage without mechanical disintegration.

The following examples are illustrative of the present invention, but are not to be construed as limiting the invention; the limits of the invention being described in the claims.

EXAMPLE I A fibrous web was wet formed from a furnish in which the fibers were 100% pictou a bleached sulfate softwood). The furnish contained P-339, 45% solids by weight, in an amount such that the dried Web contained 1% adhesive solids by weight based on the dry weight of fibers in the web. The web was dried, and 15-485, 50% solids by weight, was print bonded on the dried web in islands of a square configuration having sides which were 78" in length. The islands were oriented with their diagonals in the machine-direction of web formation, and had sub-corridors and sub-islands, as described above. The islands were spaced to define /s" wide corridor regions. The adhesive added in the islands was 4% solids by weight, based on the dry weight of the fibers in the web, and covered approximately 76.5% of the surface area of the web. The web was heated for two minutes at approximately 325 F. to dry the web and cure the adhesive. A moisturizing ingredient was added to the web in an amount of approximately 200% by weight, based on the weight of the adhesively bonded and cured web. The web had a basis weight of 30 pounds per ream of 2,880 square feet. The web had a machine direction wet tensile strength of 7.7 oz./in., and a cross-machine direction wet tensile strength of 4.3 oz./in. This web mechanically disintegrated along the corridor regions when flushed within the vortex of a conventional household toilet system.

EXAMPLE II A fibrous web was wet formed from a furnish in which the fibers were 80% by weight southern pine and 20% by weight viscose rayon, 1.5 denier, A" length. The formed web was print bonded on one surface with the square island pattern described in Example I, but with sides of 1" in length and a spacing of A" to define the corridors. The adhesive in the islands had a 4% solids weight based on the dry weight of the fibers in the web, and covered approximately 80% of the surface area of the web. The web was then sprayed on its opposite surface with E-485, 10% solids by weight, in an amount such that the web retained 4% solids by weight, based on the dry weight of fibers in the web. The web was heated at 300 F. for tWo minutes to dry the web and cure the adhesive. A moisturizing ingredient was added to the web in an amount of approximately 250% by weight, based on the weight of the adhesively bonded and cured web. The web has a basis weight of 48 pounds per ream of 2,880 square feet. The web had a machine direction wet tensile strength of 8.16 oz./in., and a cross-machine direction wet tensile strength of 6.99 oz./in. This web mechanically disintegrated along the corridor regions when flushed within the vortex of a conventional household toilet system.

What is claimed is:

1. A flushable, pre-moistened wiper capable of being packaged in a wet condition for a long period of time without disintegrating, said wiper comprising:

A. a web of soft, flexible, absorbent fibrous material having opposed major surfaces, said web including a fiber weight of at least 50% of short cellulosic fibers of a papermaking length less than inch;

B. two water-insoluble adhesive distributions associated with said web;

(1) one water-insoluble adhesive distribution being distributed over one major surface of the web in a pattern of discrete islands separated by corridor regions, said islands covering more than 50 percent of the surface area of said web and extending at least partially throughthe thickness of the Web for enhancing the wettensile strength of said web to permit use of said web in a wet condition without mechanical disintegration and for aiding in stabilizing surface fibers of said web, said web mechanically disintegrating substantially in said corridor regions when flushed within the vortex of a conventional household toilet system; and

(2) the other water-insoluble adhesive distribution disposed uniformly over the planar extent of the web and associated with at least the other major surface of said web which is opposed to said one major surface, said other water-insoluble distribution extending at least partially through the thickness of said web and having a solids weight of no more than 5% based on the dry weight of the fibers in said web; whereby said other adhesive distribution aids in providing structural integrity to said web during use, permits mechanical distintegration of the web once said web is subjected to mechanical agitation of the type encountered in conventional household toilet systems, and stabilizes the fibers on at least said other major surface of said web to enhance the abrasion resistance of said other major surface; and

C. a moisture content in said web of from between about 100% and about 350% by weight based on the dry weight of the finished web.

2. The wiper according to claim 1, wherein the adhesive in 'both said distributions is a latex.

3. The wiper according to claim 2, wherein said one latex distribution has a solids weight which does not exceed 8% based on the dry weight of the fibers in said web.

4. The wiper according to claim 2, wherein said one latex distribution has a solids weight which does not 8 exceed 6% based on the dry weight of the fibers in said web.

5. The wiper according to claim 2, wherein the latex in both said distributions is the same.

6. The wiper according to claim 3, wherein said other latex distribution is substantially uniform and continuous along the planar extent of the web and has its greatest concentration on one surface of the web and extends partially through the thickness of said web.

7. The wiper according to claim 6, wherein said other latex distribution has a solids weight of from between about 2% and about 5% based on the dry weight of fibers in the web.

8. The wiper according to claim 3, wherein said other latex distribution is substantially uniform and continuous along the planar extent of the web and extends substantially throughout the thickness of the web and has a solids Weight of from between about 0.75% and about 4% based on the dry weight of fibers in the web.

9. The wiper according to claim 3, wherein said other latex distribution is substantially uniform and continuous along the planar extent of the web and extends substantially throughout the entire web and has a solids Weight of from between about 0.75% and about 3% based on the dry weight of the fibers in the web.

10. The wiper according to claim 1, wherein all of the fibers in the web are short cellulosic fibers of a papermaking length less than one-quarter inch.

11. The wiper according to claim 1, wherein said web includes reinforcing fibers having an average fiber length of at least one-quarter inch in length.

References Cited UNITED STATES PATENTS 2,840,080 6/ 1958 Clark 117-45 3,044,895 7/ 1962 Isaacson 117-60 3,057,467 10/1962 Williams 117-76 P 3,078,849 2/1963 Morse 128-290 3,123,075 3/ 1964 Stamberger 128-287 3,129,811 4/1964 Williams 128-284 3,142,609 7/1964 Deretchin et a1. 161-39 3,536,563 10/1970 Brandts et al. 156246 3,554,788 1/1971 Fechillas 117-140 A 3,561,447 2/ 1971 Alexander 128-290 W 3,616,797 11/1971 Champaigne et al. 128-290 W WILLIAM D. MARTIN, Primary Examiner M. R. LUSIGNAN, Assistant Examiner U.S. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,846,158 Dated November 5, 1974 Inventor) Kosta O. Vasilyadis It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 30, add -s to "layer". 0 Column 4, line 39, change "Instron" to -Instrom--.

Column 5, line 9, change "dimensions" to dimension-. Column 6, line 23, add before "a bleached sulfate soft" 0 Signed and Scaled this Twenty-sixth D3) Of October 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Office Commissioner nfParenrs and Trademarks