US3151483A

US3151483A - Method and apparatus for testing the relative softness of sheet materials

Info

Publication number: US3151483A
Application number: US120413A
Authority: US
Inventors: Charles H Plummer
Original assignee: Johnson and Johnson
Current assignee: Johnson and Johnson
Priority date: 1961-06-28
Filing date: 1961-06-28
Publication date: 1964-10-06
Anticipated expiration: 1981-10-06

Description

Oct. 6, 1964 c. H. PLUMMER 3,151,433

METHOD AND APPARATUS FOR TESTING THE RELATIVE SOFTNESS OF SHEET MATERIALS 2 Sheets-Sheet 1 Filed June 28. 1961 ATTO R N EY Oct. 6, 1964 c. H. PLUMMER 3,151,483

METHOD AND APPARATUS FOR TESTING THE RELATIVE SOFTNESS OF SHEET MATERIALS Filed June 28, 1961 2 Sheets-Sheet 2 INVENTOR 074F155 flaw/v51? BY dam W4- ATTORNEY 2910 spa/w r United States Patent 3,151,483 METHGD AND APPARATUS FOR TESTWG THE RELATEVE SGFTNESS 9F SEEET MATERIALS Charles H. Plummet, Princeton, NJ assignor, by mesne assignments, to Johnson & lohnson, New Brunswick, NJ a corporation of New .lerscy Filed June 28, 1961, Ser. No. 126,413

it? Claims. (Cl. 73-159) The present invention relates to improved methods and apparatus for determining the relative over-all softness of sheet materials. More particularly, the present invention is concerned with improved methods and apparatus for determining the relative over-all softness of fibrous textile materials, notably woven, knitted and non- Woven fabrics, as Well as felts, paper and paper products.

The relative softness of sheet materials has previously been determined in many ways, one of the most popular being by means of apparatus wherein the sheet material is placed over a relatively small opening and is forced into and through the opening by a rod having a ball point with a diameter less than the diameter of the opening. In so doing, the sheet material is forced to crumple and to wrap around the ball point and the resistance offered by the sheet material to such crumpling action is deemed indicative of the softness thereof. The results of such tests are readily reproducible and are apparently accurate. However, when the results are compared to subjective tests by persons physically handling the sheet materials, there is a great disparity between the objective apparatus results and the subjective personal tests. The results of such apparatus tests, therefore, have not been completely accepted by the industry as truly indicative of the softness of the sheet materials tested.

It has now been determined that such prior tests actually measured only the fiexural softness, that is, the

pliability and flexibility of the sheet material, and did.

not measure other equally important properties, such as the tactile softness, that is, the textile hand and surface lubricity thereof.

It is therefore a principal purpose of the present invention to provide improved methods and apparatus for determining not only the flexural softness of sheet materials but also the tactile softness thereof whereby the over-all subjective softness can be determined.

Specifically, it has been discovered that, if a sample of the sheet material to be tested is placed over a rela tively small opening which tapers sonically to a relatively narrow, elongated cylindrical chamber and the sheet material is forced into the opening and through the chamber by means of a ball point having a diameter less than that of the opening, (1) the resistance offered by the sheet material to its being crumpled and forced into the opening is indicative of the flexural softness of the sheet material and (2) the subsequent frictional resistance offered by the internal walls of the relatively narrow, elongated chamber to the passage of the sheet material is indicative of the tactile softness, textile hand and surface lubricity of the sheet material. When a graph showing the total resistance offered to the passage of the sheet material into and through thetapered opening and the elongated chamber is studied, the overall subjective softness of the sheet material can be determined.

The relationship of the diameter of the ball point to the diameter of the opening and that of the elongated chamber is critical and depends upon many factors, the

most important being the weight, thickness, and other physical properties of the sheet material being tested. For very light-weight materials, the cross-sectional area of the ball point may be as much as about 30% of the area of the opening. For heavier weight materials, the cross- 3,151,43 Patented get. 6, I964 "ice 30% or less of the area of the opening. Within the more commercial aspects of the present invention, however, the cross-sectional area of the ball point should be from about 40% to about 70% of the area of the opening.

Although the present invention will be described with reference to ball points Which are spherical, openings which are circular, and elongated chambers which are cylindrical, it is to be appreciated that such is done because of the ease of Working with such geometric figures. Other geometric figures may be employed provided they do notpossess too great eccentricity. For example, the spherical ball point could be an ellipsoid (with the long axis preferably vertical) or other figures, preferably having a horizontal circular or nearcircular cross-section, or a cross-section of low eccentricity. Similarly, the opening and the elongated chamber could be circular, near-circular or elliptical in cross-section corresponding to the cross-section of the ball point. Such other noncircular shapes and figures occasionally yield results which are not completely reproducible and consequently the spherical ball point, the circular opening and the cylindrical chamber are preferred.

The materials of which the ball point, the circular ring forming the opening, and the walls of the elongated chamber are made are preferably selected from metallic or plastic sources so that they can be polished relatively smooth. If desired, the metallic surfaces may be iron or steel which may be nickel plated or chrome plated, as desired. If a plastic material is used, either a thermosetting resin, such as phenol formaldehyde, or a thermoplastic resin, such as polyamide nylon, may be used.

Although the present invention will be described with particular reference to a nonwoven fabric as the sheet material, it is to be appreciated that such as done primarily for illustrative purposes and that such is not to be construed as limitative of the broader aspects of the present invention. It is to be appreciated that other sheet materials are applicable to the present invention. Examples of other sheet materials include woven, knitted, and braided fabrics; felts, plastic films, paper and paper products.

In the following specification and accompanying drawings, there are described and illustrated preferred embodiments of the invention but it is to be understood that the inventive concept is not to be considered limited to the embodiments disclosed except as determined by the scope of the appended claims. In the drawings:

FIGURE 1 is a diagrammatic and schematic drawing in side elevation showing apparatus capable of carrying out the methods of the present invention;

FIGURE 2 is a graph of Pounds (Force) vs. Displacement (Inches) obtained in testing an 8" x 8" sample of sheet material in a ring tester such as used in the prior art, the ring tester having an axial length of about onehalf inch; 7

FIGURE 3 is a graph of Pounds of (Force) vs. Displacement (inches) obtained in testing an 8" x 8 sample of sheet material in a funnel tester of the present invention,,wherein the axial length of the tapered opening portion of the funnel is 1 inch and the axial length of the cylindrical bore of the funnel is 4 inches; and

FIGURE 4 is a graph of the Pounds (Force) vs. Displacement (Inches) obtained in testing an 8" x 8" sample of sheet material in a. funnel tester of the present in-,

10 upon which a sample S of the sheet material may be placed in order that its relative over-all softness can be determined. The sample mounting plate 10 is preferably substantially square and is supported at each of its four corners by rotatable screw-threaded support rods 12 which are rotatably mounted within sockets 14 located at each of the corners of the sample mounting plate 19.

The rotatable screw-threaded support rods 12 are threaded into fixed, internally-threaded annular bushings 16 provided in a fixed, base plate 18. The rotatable screw-threaded support rods 12 are adapted to be rotated in the same direction at the same rate by any desired mechanical means (not shown) and are adapted to raise or lower the sample mounting plate ill at a desired rate.

An opening is provided in the central portion of the sample mounting plate l and is adapted to removably receive the funnel tester 29 which is the essence of the present invention.

The funnel tester comprises an annular mounting block 21 having a flared or tapered portion 22 and a substantially cylindrical bore portion 24 consisting of a cylinder 23 which is forced into a bore in the lower portion of the mounting block 21. As noted in FIGURE 1, the surface of the flared portion 22 and the internal portion of the cylindrical bore 24 smoothly converge into each other in substantially one continuous curve.

Vertical supporting brackets 30 are provided at each of the four corners of t e fixed base plate 18 and rigidly support an upper plate 32 upon which is mounted a conventional dial indicator 34. The sensing arm 35 of the dial indicator 3% is attached to an elongated testing rod 36 provided with a substantially spherical ball point end 38. The dial indicator 34 is, of course, fixed and stationary; the sensing arm 35 and the ball point 38 may be urged upwardly by force applied upwardly against the ball point 38. Such force is reflected in the readings of the dial indicator, which readings can be inversely related to softness through arbitrarily designed linear or non-linear relationships. If desired, a more permanent record may be obtained by means of a conventional stylus and recording paper type of testing instrument.

The operation of the testing device is as follows: a sample S of the sheet material is placed on the sample mounting plate and is so positioned that the ball point end 33 of the testing rod 36 is positioned substantially directly above the geometric center of the sample. The mechanical drive means for rotating the screw-threaded support rods 12 is then activated and the screw-threaded support rods 12 slowly rotate within the internally threaded annular bushings 16 to slowly elevate the sample mounting plate 10.

When the sample 8 is elevated sufliciently so initially contacts the ball point end 38 of the testing rod 36, the ball point end 38 is urged upwardly with a force depending upon the resistance offered by the sample S to the crumpling action thereon by the ball point end 38.

As the tapered upper portion 22 of the funnel tester Z9 surrounds the ball point 33 more and more, the sample S is gradually crumpled completely about the testing rod as. The resistance offered to this crumpling action is translated into a reading on the dial indicator 34 that it which indicates the relative fiexural softness or resistance to crumpling of the sample S.

As the ball point end 38 enters the substantially cylindrical bore 24 of the funnel tester 29, the crumpled sample S begins to be additionally retarded by the friction offered by the internal surface of the cylindrical bore 24. This frictional resistance is additive to the resistance to crumpling and the reading on the dial indicator 34 is increased correspondingly. As the crumpled sample enters more and more into the cylindrical bore 24, the area of frictional contact between the sample S and the internal walls of the cylindrical bore 24 increases and the readings on the dial indicator 34 increase correspondingly.

The readings on the dial indicator 34- increase until there is a maximum of area contact between the sample S and the internal walls of the cylindrical bore 24. When the ball point end 38 of the testing rod 36 emerges completely through the cylindrical bore 24, the area of contact between the crumpled sample S and the internal walls of the cylindrical bore 24 decreases until the trailing end of the sample S completely emerges through the cylindrical bore 24. At that point, the resistance noted on the dial indicator falls to 0.

In the event that the cylindrical bore 24 of the funnel tester 20 is not long enough so as to provide complete frictional con-tact between its internal walls and the full length of the doubled test sample, it will be appreciated that the maximum resistance will not be ofiered to the passage of the test sample. In other words, the length of the cylindrical bore should be at least equal to approximately half the minimum dimension of the test sample in order that a maximum reading is obtainable.

In the event that the length of the cylindrical bore is considerably greater than half the minimum dimension of the test sample and the test sample slides therein for a considerable distance, no error results inasmuch as the maximum resistance is reached when all of the test sample is within the cylindrical bore. Continued passage of the doubled test sample within the cylindrical bore merely leads to an approximately horizontal dwell in the reading on the dial indicator.

However, if the length of the cylindrical bore is considerably less than half the minimum dimension of the test sample, it is apparent that it cannot accommodate the length of the doubled sample. As a result, some of the trailing length of the test sample will not have entered the cylindrical bore when the leading end emerges from the other end of the cylindricalbore. As a result, a true maximum softness reading is not obtained and inaccuracy results.

But, if the length of the cylindrical bore is only slightly less than half the minimum dimension of the test sample, it will accommodate mostly all of the length of the doubled sample and readings are obtained which, although not maximum readings and therefore not completely accurate, are sufliciently close to maximum readings and are reasonably accurate. At least, they are sufiiciently accurate as to permit extrapolation and reasonable prediction of maximum values.

Although it is preferred to define the length of the cylindrical bore of the funnel tester of the present invention in terms of the minimum dimension of the test sample of sheet material, namely, that the cylindrical bore be at least about half the minimum dimension of the test sample, such is not always possible or practical due to the varying sizes, shapes, weights and thicknesses of test samples available. It is therefore more desirable in some cases to define the length of the cylindrical bore in terms of a more constant standard. It has been established that, in order to provide enough length of test sample to create sufiiciently measurable frictional resistance, the minimum dimension of the test sample must be at least greater than twice the diameter of the cylindrical bore. Since the minimum dimension of the test sample must be at least equal to twice the length of the cylindrical bore, it naturally follows that in all cases, the length of the cylindrical bore must always be greater than the diameter thereof. This is, of course, an absolute minimum. In actual practice, it-is' found more desirable to have the length of the cylindrical bore four or six times the diameter thereof to insure enough length to provide sufficient measurable frictional resistance.

The size and shape of the test sample S should be maintained Within certain desired criteria. The minimum physical dimension (width) of the test sample should be sufficiently long as to provide a considerable length for frictional resistance to the internal bore of the funnel tester. By minimum dimension is meant the lesser of the two dimensions of length and width of the test sample. In the case of a circular test sample, which is preferable in many instances, the diameter is, of course, the minimum dimension. In the case of a square sample, the side thereof is the minimum dimension. In the case of a rectangular test sample, the width is the minimum dimension and care should be taken that the minimum and maximum dimensions, that is the width and the length dimensions, respectively, should not be too different.

In FIGURE 2 there is illustrated a graph of the Pounds '(Force) vs. Displacement (Inches) obtained by testing an 8" x 8" sample by a half-inch long ring tester of the prior art. As the ball point of the test rod contacts the test sample and begins to crumple it (Point A), the resistance in Pounds (Force) rises essentially linearly to a maximum (Point B) after about 4 /2 inches of Displacement, at which point the trailing end of the 8" x 8" sample penetrates completely through the ring and opens to a relatively uncrumpled configuration whereat the resistance in Pounds (Force) abruptly collapses to 0 (Point C). Such a graph measures only the flexural softness of the sample.

In FIGURE 3 there is illustrated a graph of the Pounds (Force) vs. Displacement (Inches) obtained by testing and 8" x 8" sample by a funnel test of the present invention. Such a funnel has .a tapered bore length of 1 inch and a cylindrical bore charnber of 4 inches. As the ball point of the test rod contacts the test sample and begins to crumple it (Point D), the resistance rises essentially linearly for about 1 inch of Displacement. At that time, the leading end of the sample begins to enter the cylindrical bore chamber of the funnel and additional resistance is oifered by the friction of the internal Walls of the cylindrical bore of the funnel. As a result the Pounds (Force) rises with increased steepness, being the sum of the resistance to the crumpling action and the frictional resistance. The Pounds (Force) rises steadily to a maximum (Point E) until the leading end of the sample begins 'to penetrate completely through the cylindrical bore of the funnel. As the sample continues to emerge from the cylindrical bore of the funnel, the frictional resistance steadily falls oli until at 9 inches Displacement, the sample completely penetrates through the cylindrical bore and the Pounds (Force) is then 0 (Point E). The difference between the curve obtained with the funnel tester is strikingly different than the curve obtained with a ring tester. The curve obtained by the funnel tester measures not only the flexural softness but also the tactile softness.

In FIGURE 4 there is illustrated a graph of the Pounds (Force) vs. Displacement (Inches) obtained bytesting an 8" x 8" sample by a funnel tester in which the length of the tapered bore is still 1 inch but the cylindrical bore is increased from 4 inches to 11% inches. The initial part of the curve, all the way from the initial contact (Point G) up to the maximum (Point H), is basically the same as the curve obtained with the apparatus of FIGURE 4. However, due to the increased length of the cylindrical bore, a horizontal dwell (line H1) is obtained corresponding to the increased length of the cylindrical bore. Then, when the leading end of the sample begins to penetrate completely through the end of the funnel, the resistance in Pounds (Force) drops steadily in precisely the same way as it would with the appratus of FIGURE 3. Finally, at 16%, inches Displacement, the trailing end penetrates completley through the funnel tester and the resistance in Pounds (Force) is 0 (Point I). Analysis of the curve obtained in FIGURE 4 reveals that the increased length of bore adds nothing materially to the information available in the curve of FIG- URE 3.

The invention will be further illustrated in greater detail by the following specific examples. It should be understood,-however, that although these examples may describe in particular detail some of the more specific features of the invention, they are given primarily for purposes of illustration and the invention in its broader aspects is not to be construed as limited thereto.

Example I The test sample is an 8 x 8" sample of a bonded nonwoven fabric prepared from viscose rayon fibers having a staple length of 1% inches and a denier of 1.5. The Weight of the nonwoven fabric is approximately 250 grains per square yard. A ball point having a diameter of 0.62 inch is used to force the sample through a ring The test sample is an 8" x 8" sample of a bonded nonwoven fabric prepared from 100% viscose rayon fibers having a staple length of 1% inches and a denier of 1.5. The weight of the nonwoven fabric is approximately 250 grains per square yard. This sample is passed through a funnel tester of the present invention, such as illustrated in FIGURE 1, and a curve such as noted in FIGURE 3 is obtained. The diameter of the ball point is 0.62 inch; the tapered ring opening tapers from an entrance opening of 2.4 inches to a minimum opening of 0.865 inch. The axial length of the tapered opening portion of the funnel is 1 inch and the axial length of the cylindrical bore (0.865 inch) of the funnel is 4 inches. The maximum reading on the dial indicator is 0.51 and indicates not only the flexural softness but also the tactile softness.

' Example III The test sample is an 8" x 8" sample of a bonded nonwoven fabric prepared from 100% Viscose rayon fibers having a staple length of 1% inches and a denier of 1.5. The weight of the nonwoven fabric is approxi-. mateiy 250 grains per square yard. This sample is forced through a funnel tester of the present invention by 'a ball point having a diameter of 0.62 inch and Wherein the length of the tapered opening portion of the funnel is again 1 inch as in Example II but the length of the cylindrical bore (0.865 inch) is 11 /2 inches. A curve, such as noted in FIGURE 4, is obtained with a maximum reading of 0.51. Such indicates not only the flexural softness but also the tactile softness.

The horizontal dwell obtained at the reading of 0.51 indicates that the cylindrical bore of the funnel was longer than necesary. Such increased length, however, does not affect the accuracy of the results. Asa matter of fact, it is desirable that the length of the cylindrical bore be slightly greater than M. the minimum dimension of the test material in order that there be a short dwell which will accentuate the maximum reading.

An analysis of the results of Examples I, II and III shows that, although the material tested in the same in all three examples, the first example dealing with the use of a ring tester yields an abnormally low reading which would lead one to believe that this sample is the softest. Actually, all three samples are alike.

The results of these three examples establish that the use of a ring tester determnies only the flexural softness whereas the funnel testers of Example .11 and III determines not only the flexural softness but also the tactile softness. t

Further tests on related textile materials such as nonwoven fabrics and gauze reveal that, if the ring tester of the prior art is used, it is quite possible to obtain identical readings for the two samples. However, upon a subjective personal test, the gauze is found to be considerably harsher than the nonwoven fabric.

If these samples of nonwoven fabrics and gauze are tested in the funnel tester of the present invention, however, it can be determined that their flexural softness is approximately the same in that substantially identical readings are initially obtainable. However, when these samples are forced into the cylindrical bore portion of the funnel tester of the present invention which additionally determines the tactile softness, it is established that the tactile softness of the nonwoven fabric is very much lower than the tactile softness of the gauze and hence is far more desirable when over-all softness, that is, a combination of flexural softness and tactile softness, is desired. The results of the funnel tester therefore relate accurately and directly to the subjective personal tests.

Although several specific examples of the inventive concept have been described, the same should not be construed as limited thereby nor to the specific features mentioned therein but to include various other equivalent features as set forth in the claims appended hereto. It is understood that any suitable changes, modifications and variations may be made without departing from the spirit and scope of the invention.

What is claimed is:

l. A method of determining the flexural and tactile softness of sheet material which comprises: placing the sheet material over an opening leading to an elongated chamber; forcing the sheet material (l) into the opening which is sufficiently small as to constrict the sheet material entering therein and (2) through the elongated chamber which is sufficiently small throughout its length as to resist frictionally the passage of the constricted sheet. material therethrough; and measuring the resistance offered by the sheet material to its passage into the opening and through the elongated chamber whereby the fiexural and tactile softness thereof is determinable.

2. A method of determining the flexural and tactile softness of sheet material which com rises: placing the sheet material over an opening leading to an elongated chamber; forcing the sheet material into the opening which is sufiiciently small as to constrict the sheet material entering therein; measuring the resistance to constriction offered by the sheet material whereby the flexural softness thereof is determinable; forcing the constricted sheet material into and through the elongated chamber which is sufficiently small throughout its length as to resist frictionally the passage of the constricted sheet material therethrough; and measuring the resistance offered by the constricted sheet material to its passage through the elongated chamber whereby the tactile softness thereof is determinable.

3. Apparatus for determining the flexural and tactile softness of sheet material which comprises: a surface upon which sheet material may be placed; said surface having an opening leading to an elongated chamber; means for forcing the sheet material (1) into the opening which is sufficiently small as to constrict the sheet material entering therein and (2) through the elongated chamber which is sufiicien-tly small throughout its length as to resist frictionally the passage of the constricted sheet material thcrethrough; and means for measuring (1) the resistance to constriction offered by the sheet material and (2) the frictional resistance offered by the constricted sheet material to its passage through the elongated chamber, whereby the flexural softness and the tactile softness thereof is determinable.

4. Apparatus for determining the flexural and tactile softness of sheet material which comprises: a surface upon which sheet material may be placed; said surface having an opening leading to an elongated chamber; means for forcing the sheet material (1) into the opening which is sufficiently small as to .constrict the sheet material entering therein and (2) through the elongated chamber which is sufliciently small throughout its length as to resist frictionally the passage of the constricted sheet material therethrough, the length of said chamber being softness of sheet material which comprises: a surface upon which sheet material may be placed; said surface having an opening leading to an elongated chamber; means for forcing the sheet material (1) into the opening which is sufficiently small as to constrict the sheet material entering therein and (2) through the elongated chamber which is, sufliciently small throughout its length as to resist frictionally the passage of the constricted sheet material therethrough, the length of said chamber being atleast equal to about half the minimum dimension of the sheet material; and means for measuring (1) the resistance to constriction offered by the sheet material and 2) the frictional resistance offered by the constricted sheet material to its passage through the elongated chamber, whereby the fiexural softness and the tactile softness thereof is determinable.

6. Apparatus for determining the flexural and tactile softness of sheet material which comprises: a surface upon which sheet material may be placed; said surface having a circular opening leading to an elongated cylindrical chamber; means having a circular cross section for forcing the sheet material (1) into the circular opening which has a sufiiciently small diameter as to constrict the sheet material entering therein and (2) through the elongated cylindrical chamber which has a sufficiently small diameter throughout its length as to resist frictionally the passage of the constricted sheet material therethrough; and means for measuring (1) the resistance to constriction offered by the sheet material and (2) the frictional resistance offered by the constricted sheet material to its passage through the elongated cylindrical chamber, whereby the flexural softness and the tactile softness thereof is determinable.

7. Apparatus for determining the flexural and tactile softness of sheet material which comprises: a surface upon which sheet material may be placed; said surface having a circular opening leading to an elongated cylindrical chamber; a rod having a spherical ball point end for forcing the sheet material (1) into the circular opening which has a sufliciently small diameter as to constrict the sheet material entering therein and (2) through the elongated cylindrical chamber which has a sufiiciently small diameter throughout its, length as to resist frictionally the passage of the constricted sheet material therethrough; and means for measuring (1) the resistance to constriction offered by the sheet material and (2) the frictional resistance offered by the constricted sheet material to its passage through the elongated cylindrical chamber, whereby the flexural softness and the tactile softness thereof is determinable.

8. A method of determining the flexural and tactile softness of sheet material which comprises: placing the sheet material on a surface having an opening; forcing the sheet material (1) initially into the opening which is sufliciently narrow as to constriot resistingly the sheet material entering therein and 2) subsequently through a passage which is (a) sufficiently narrow throughout its length as to resist frictionally the movement of the sheet material therethrough and (b) sufficiently long as'to accommodate at least substantially all of thelength of the constricted sheet material; and measuring the resistance offered by the sheet material to its entry initially into the opening and subsequently through the passage whereby the flexural and tactile softness thereof is determinable.

ciently small as to constrict resistingly the sheet material entering therein; measuring the resistance to constriction offered by the sheet material whereby the flexural softness thereof is determinable; subsequently forcing the constricted sheet material into a passage which is (a) sufiiciently narrow throughout its length as to resist frictionally the movement of the sheet material therethrough and (b) sufficiently long as to accommodate at least substantially all of the length of the constricted sheet material; and measuring the resistance uttered by the con- 10 stricted sheet material to its movement through the passage whereby the tactile softness is determinable.

10. Apparatus for determining the fiexural and tactile softness of sheet material which comprises: a surface upon which sheet material may be placed; said surface having an opening leading to an elongated chamber; means for forcing the sheet material (1) into the opening which is sufiiciently small as to constriet the sheet material entering therein and (2) through the elongated chamher which is (a) sufficiently small throughout its length as to resist frictionally the passage of the constricted sheet material therethrough and (b) sufficiently long as to accommodate at least substantially all of the length of the constricted sheet material; and means for measuring (1) the resistance to constriction oifered by the sheet material and (2) the frictional resistance offered by the constricted sheet material to its passage through the elongated chamber, whereby the flexural softness and the tactile softness thereof is determinable.

References Cited in the file of this patent UNITED STATES PATENTS Wharton May 6, 1958 2,930,229 Sobota Mar. 29, 1960 3,026,726 Reading Mar. 27, 1962

Claims

3. APPARATUS FOR DETERMINING THE FLEXURAL AND TACTILE SOFTNESS OF SHEET MATERIAL WHICH COMPRISES: A SURFACE UPON WHICH SHEET MATERIAL MAY BE PLACED; SAID SURFACE HAVING AN OPENING LEADING TO AN ELONGATED CHAMBER; MEANS FOR FORCING THE SHEET MATERIAL (1) INTO THE OPENING WHICH IS SUFFICIENTLY SMALL AS TO CONSTRICT THE SHEET MATERIAL ENTERING THEREIN AND (2) THROUGH THE ELONGATED CHAMBER WHICH IS SUFFICIENTLY SMALL THROUGHOUT ITS LENGTH AS TO RESIST FRICTIONALLY THE PASSAGE OF THE CONSTRICTED SHEET MATERIAL THERETHROUGH; AND MEANS FOR MEASURING (1) THE RESISTANCE TO CONSTRICTION OFFERED BY THE SHEET MATERIAL AND (2) THE FRICTIONAL RESISTANCE OFFERED BY THE CONSTRICTED SHEET MATERIAL TO ITS PASSAGE THROUGH THE ELONGATED CHAMBER, WHEREBY THE FLEXURAL SOFTNESS AND THE TACTILE SOFTNESS THEREOF IS DETERMINABLE.