NZ227334A - Sheet material having laterally extending ribs formed therein - Google Patents

Description

Und«r the provisions of Regulation 23 (!) the Specification h*s been ante-dated to 13 *2 *6 Vj *;5 i : .0. Jo- I Initials Patents Form No. 5 NEW ZEALAND PATENTS ACT 195 3 COMPLETE SPECIFICATION "COMPOSITE SHEET MATERIAL" I/We, SCOTT & FYFE LIMITED, a British Company of Scotscraig Works, Tayport, Fife, Scotland, DD6 9DQ hereby declare the invention, for which #/we pray that a patent may be granted to $>^/us, and the method by which it is to be performed, to be particularly described in and by the following statement: (Followed by page la) cl 7 3 -lpi COMPOSITE SHEET MATERIAL This invention relates to composite sheet material and more particularly to a composite sheet material comprising rows of stitches formed in a base sheet.

This Application is divided from our co-pending Patent Application No. 218042.

The present Applicants previously developed a composite sheet material which is a stitched crepe paper and the manufacture of which is described and 10 claimed in U.K. Patent No. 1,422,940. This stitched crepe paper product has properties which make it particularly suitable as a backing for a carpet underlay, the product having dimensional stability and being capable of adhesion to a sheet of foamed 15 or sponge rubber.

The present Applicants have now developed an improved method of making a composite sheet material having longitudinal rows of stitches to provide dimensional stability. This method, which is claimed 20 in our co-pending Patent Application No. 218042 from which the present Application is divided, enables the product to be stronger and thicker than the product of U.K. Patent No. 1,422,940, and to have greater depth in the gaps between the stitches thus making 25 the product more suitable for adhering to materials other than rubber materials, for example synthetic resin materials in any suitable form.

In co-pending Patent Application No. 218042 30 there is described and claimed a method of producing composite sheet material comprising the steps of feeding a sheet material to a stitching machine, forming longitudinal rows of stitches in the fed sheet material, and, during the formation of each stitch, increasing 22 7 3 the length of the fed sheet material such that, when the stitches are formed, there is entrapped, within each stitch in each longitudinal row of stitches formed in the sheet material, a portion of fed sheet material 5 having a length greater than the length of the completed stitch.

As a result of entrapping within each stitch a portion of the fed sheet material having a length greater than the length of the completed stitch there 10 is formed a stitched corrugated product having laterally extending corrugations, ridges or ribs according to the additional amount of sheet material gathered within each stitch. These corrugations, ridges or ribs cause there to be a greater depth in the gaps between the 15 stitches than in the stitched crepe paper product of U.K. Patent No. 1,422,940. The product is therefore more suitable for adhering to other materials, for example in forming laminates. Also the product has greater lateral flexural rigidity than the known 20 stitched crepe paper product.

The method which is described and claimed in the co-pending Patent Application No. 218042 has particular application in the manufacture of composite sheet material from paper sheet material but it is 25 not limited to the use of paper. The method may be used to produce composite sheet materials from other flexible sheet materials than paper, for example plastics film may be employed. The method enables the composite sheet material to be formed from a base 30 sheet material which is either plain or creped. In addition the composite sheet material may be formed from a plurality of sheets of base sheet material fed simultaneously to a stitching machine which stitches through all the plurality of sheets to stitch them 35 together. Thus varying degrees of bulk may be obtained 22 7 3 3 4 in the resulting product, increasing from the case when the base sheet material is a plain sheet material through the case where crepe sheet material is used to the still greater bulk which is obtained using 5 two or more sheets of the base sheet material.

The increase in the length or lengths of base sheet material used per stitch in the said method may be effected by the needles, which are used to form the rows of stitches, themselves moving the sheet 10 materials without piercing thereof to withdraw the increased length of sheet material or sheet materials from a supply roll or rolls. In such case the needles employed are preferably round-headed needles.

Alternatively, the increase in the length or 15 lengths of sheet material used per stitch may be effected by advancing sheet materials to the needles, which are used to form the rows of stitches, at a rate faster than the rate required to match the rate of stitching. Slack sheet material, which is thereby 20 provided in the region of the needles, is moved by the needles through a predetermined distance without piercing the sheet material, the needles thereafter piercing the sheet material and forming the stitches.

When a crepe sheet material is used as a base 25 sheet material it is surprisingly found that the length of sheet material used per stitch may be increased using round-headed needles to increase the length of sheet material used per stitch. It is surprising that the action of the needles on, for example, a 30 crepe paper sheet material results in a withdrawal of a greater length of crepe paper sheet material from the feed roll rather than an opening of the crimps in the crepe paper. A bulkier product with increased lateral flexural rigidity as compared with the use 35 of plain paper sheet material is obtained as a result 22 7 3 3 4 of the superimposition of corrugations, ridges or ribs upon a sheet material which is already creped.

When a plurality of sheets of sheet material is employed, the lengths of all the sheet materials 5 used per stitch may be increased, in which case laterally extending corrugations, ridges or ribs are formed in all the sheet materials. Alternatively, however, the increase in length may be provided in some only of the sheet materials in which case there 10 is formed a composite product having, for example, a flat sheet material on one surface and a corrugated sheet material on the other surface. The corrugated sheet material in this product may be formed by increasing the length of sheet material used by either 15 of the methods described, that is to say either by the action of the needles on the base sheet material or by the act of feeding sheet material to the stitch bonding machine faster than the material is being stitched, and thus creating a quantity of the slack 20 sheet material in the stitching machine.

The composite sheet material may comprise three layers of, for example, paper sheet material, an increase in the length of sheet material entrapped within each stitch being provided for the two outer 25 sheets of sheet material but not for the central sheet of the three. Preferably, in such a case, the increase in length of the two outer sheets is provided by overfeeding these sheet materials, and the central sheet is advantageously a crepe paper sheet material.

Usually only two sheets of sheet material will be employed to form a product having stitches through the plurality of sheet materials. It is envisaged that, however many sheets are employed, the sheet materials may be any combination of plain and crepe 35 sheet materials. When two sheets are used, both sheets 22 7 3 may be plain paper sheet materials, both may be crepe paper sheet materials, or there may be one plain paper sheet material and one crepe paper sheet material. In this last case, either the plain paper sheet material 5 or the crepe paper sheet material may be first pierced by the needles.

The products obtained by the method of the copending Patent Application No. 218042 may include weft threads in order to increase further the transverse 10 tensile strength, and hence the longitudinal tear strength, of the resultant product. Such weft threads are retained in the composite sheet material by the stitching. When the product comprises a plurality of sheet materials the weft threads may be applied 15 either to the outside surface of one or other of the sheet materials or be laid between the two sheet materials before these are brought together for stitching so that the weft threads in the final product are concealed.

There are two types of stitching machine which include provision for laying weft threads. In one type of stitching machine the weft threads are laid at right-angles to the direction of advancement of the sheet material, which is also the direction of 25 the stitching. In the other type of machine the weft threads are laid obliquely to the direction of advancement. Either type of machine may be used to lay the weft threads which are concealed between the two sheets of sheet material. When the weft threads 30 are concealed in this manner, the appearance of the ultimate product is not affected by the choice of the type of stitching machine, but the appearance will be affected when the weft threads are laid on an outside surface of one of the sheet materials.

In accordance with the present invention weft 22 7 3 threads present on an exposed surface of the composite sheet material are largely obscured by making the composite sheet material using the type of stitching machine in which the weft threads are laid at right-5 angles to the direction of stitching. In such cases a weft thread may be laid for each stitch, and an upstanding hump or ridge of the sheet material, which is caused to lean at an angle to the general plane of the composite sheet material by the stitching yarn, 10 will at least partially obscure the weft thread.

In accordance with the present invention, therefore, there is provided a composite sheet material comprising a sheet material having a longitudinal series of laterally extending deformed tubular ribs 15 formed therein, the ribs being entrapped within and deformed by a series of side-by-side longitudinally extending rows of stitches formed in the sheet material, and a series of weft yarns, each weft yarn being laid adjacent to a laterally extending deformed tubular 20 rib and being at least partially obscured by the adjacent laterally extending deformed tubular rib.

Further in accordance with the present invention there is provided a composite sheet material comprising a plurality of sheets of sheet material, a series 25 of side-by-side longitudinally extending rows of stitches which extend through the plurality of sheets of sheet material, one of the sheets of sheet material having a longitudinal series of laterally extending deformed tubular ribs formed in an exposed surface 30 thereof, the ribs being entrapped within and deformed by the longitudinally extending rows of stitches, and a series of weft yarns, each weft yarn being laid adjacent to a laterally extending deformed tubular rib and being at least partially obscured by the 35 adjacent laterally extending deformed tubular rib. 22 733 In co-pending Patent Application No. 227333 which is also divided from co-pending Application No. 218042 there is claimed a composite sheet material comprising a crepe sheet material having a longitudinal 5 series of laterally extending tubular ribs formed therein, the ribs being maintained in tubular form in the crepe sheet material by a series of side-by-side longitudinally extending rows of stitches formed in the crepe sheet material.

The present invention will be further understood from the following detailed description which is made, by way of example, with reference to the accompanying schematic drawings, in which Figures 1 to 5 show one set of the main functional 15 elements of a stitch-bonding machine in positions adopted successively during the formation of a single stitch in a method according to co-pending Patent Application No. 218042, Figure 6 is a cross-sectional view on a greatly 20 enlarged scale of a portion of one embodiment of a composite sheet material according to the present invention encompassed by two stitches in a plain paper sheet material, Figure 7 is a diagrammatic representation of 25 a portion of a second embodiment of a composite sheet material according to the present invention encompassed by four stitches in a crepe paper sheet material, and Figure 8 is a diagrammatic representation of 30 a portion of a third embodiment of a composite sheet material according to the present invention including two sheets of a paper sheet material.

In the drawings the same or similar parts are designated by like reference numerals.

In the diagrammatic representations of Fis^grfes 1 d'^. f30JUNl989i 22 7 3 3 4 to 5 and the enlarged cross-sectional view of Figure 6 the hole in the paper through which stitching yarn passes is shown as a gap in the paper sheet material.

Figures 1 to 5 of the drawings each show a single 5 needle and stitching, but it will be appreciated that the machine contains a row of similar needles extending over the full width of the sheet material and performing the same movements simultaneously.

Referring to Figure 1 there is shown a sheet 1 10 of plain paper which is passing between an outer surface 2 of a knock-over bar 3 and a restraining surface 4 formed by a series of fingers comprising a sinker unit 5. A stitching yarn 6, which has already formed stitches 7 in the sheet 1 of plain paper passes 15 over a hood 8 of a round-headed stitching needle 9, and thence through the sheet 1 of plain paper and through an eyelet 10 which guides the feed of the stitching yarn 6.

The arrow 11 in Figure 1 indicates the action 20 of take-off rollers (not shown) in drawing the sheet 1 through the stitch-bonding machine. The sheet 1 is supplied on a feed-roller 12 from which it is drawn as a result of the tractive forces applied by the take-off rollers and the stitching needles, as will 25 be described.

In the position shown in Figure 1, the needle 9 is advancing in the direction of the arrow 13 to pass the upper surface 2 of the knock-over bar 3 towards the fingers of the sinker unit 5 with a loop of 30 stitching yarn 6 placed in the hook 8 of the needle 9 during the previous stroke. The needle hood 8 is closed by a closing wire 14.

The advance of the round-headed needle 9 in the direction of the arrow 13 causes the needle 9 22 7 3 34 to lift the sheet 1 rather than to pierce the sheet 1, thereby causing more of the sheet 1 to be withdrawn from the feed roller 12.

Referring now to Figure 2 the needle 9 has 5 advanced almost to the point of contact with the sinker unit 5, lifting the sheet 1 of plain paper while doing so. During this movement the closing wire 14 is retracted to open the needle hook 8 and allow the stitching yarn 6 to exit from the hook 8 as the needle 10 9 rises. This yarn now lies around the shank portion 16 of the needle 9. At the position shown in Figure 2 the extra length of the sheet 1 withdrawn from the feed roller 12 is shown draped over the round head of the needle 9, in the form of an upstanding ridge 15 in the sheet 1, which extends across the width of the sheet 1 under the action of the other needles in the row.

Referring to Figure 3, the needle 9 has advanced through the fingers of the sinker unit 5 which has 20 restrained the sheet 1 of plain paper with the result that the needle 9 has penetrated the sheet 1. In Figure 3 the needle 9 is shown at the top of its stroke and, with its hook 8 open, the needle 9 has received a futher loop of yarn 6 fed as a result of the shogging 25 action of the eyelet 10.

In Figure 4 the needle 9 is shown during the first part of the return stroke when the closing wire 14 has advanced to close the hook 8. The stitching yarn 6 is thus withdrawn through the sheet 1 of plain paper 30 by the needle 9, entrapping within the stitch which is in the process of being formed, a length of the sheet 1 greater than the length of the stitch, as a result of the sheet 1 having been lifted as described with reference to Figure 2 to form a ridge in the 35 sheet. 22 7 3 In Figure 5 the needle 9 with its hook 8 closed has been withdrawn below the sheet 1 of plain paper which is now retained by the upper surface 2 of the knock-over bar 3, which also ensures that the loop 5 of stitch yarn 6 previously lying around the shank 16 of the needle 9 passes over the closed hook and round the yarn now trapped in the hook 8. The stitch thus formed is pulled tight by the forward draw-off motion of the take-off rollers.

In pulling tight, the upstanding ridge in the sheet 1 is trapped within the stitch and is forced to form a roll or crinkle lying across the finished material within each lateral row of longitudinal stitches 7. This roll or crinkle, as may readily 15 be seen from the accompanying drawings and more particularly from Figure 6, is deformed by the stitch 7 in a forward direction, i.e. in the direction of travel of the sheet 1 through the stitch bonding machine.

The roll or crinkle 19 (Figure 6) formed across 20 the width of the sheet 1 by the stitching action constitutes a tubular rib extending across the width of the composite sheet material, giving the final stitched paper product effectively a greater thickness and a greater lateral flexural rigidity, i.e. a greater 25 resistance to lateral bending, than the stitched crepe paper product according to U.K. Patent No. 1,422,940 when paper of comparable weight is used in both methods. As shown in Figure 6, weft yarns 20 are laid on the sheet 1 and the deformed rolls or crinkles in the 30 sheet 1 of plain paper substantially cover the laid weft yarns 20 from view in the normal case where there is a single weft yarn 20 for each stitch and the weft yarn 20 is laid at right angles to the direction of stitching.

It has been found that a satisfactory stitched 2 2 7 3 3 4 paper product may be obtained by the method described with reference to the accompanying drawings when the spacing between the outer surface 2 of the knock-over bar 3 and the surface 4 constituted by the fingers 5 of the sinker unit 5 is of the order of 4 to 5 mm.

A gap of this dimension enables an upstanding ridge to be formed in the paper and contrasts with the arrangement .employed in manufacturing the product of U.K. Patent No. 1,422,940 in which the gap between 10 the knock-over bar and the sinker unit is just sufficient comfortably to pass the crimped or creped paper and the weft yarns alid thereon. The gap normally employed for this purpose is of the order of 1.5 mm.

In the successful practice of the method herein 15 described a plain paper of weight of approximately 40 grammes per square metre was employed and the stitch-bonding machine was run at a speed of 400 stitches per minute. The tractive force on the paper was provided by the take-off rollers and the stitching 20 action as described. It is envisaged that the machine can be run at higher speeds approaching the speed of 1000 stitches per minute used in the performance of the method of U.K. Patent No. 1,422,940, but it may then be desirable, in order to avoid premature 25 penetration of the paper by the needle, to include on the feed roller 12 a tension release device which can probably be a suitable gear drive or a slipping clutch.

The product in accordance with this embodiment 30 of the present invention formed with a suitably extensible stitching yarn, e.g. a polypropylene yarn, may be hot-stretched to almost twice its original length with a resultant flattening of the tubular rolls or crinkles constituting the laterally extending 35 ribs in the composite sheet material. Although paper 22 7 3 has been described as the sheet material, it is envisaged that other flexible materials, for example plastics film, may be employed.

The composite sheet material prepared from plain 5 paper sheet material by the method of the present invention as hereinbefore described is a more rugged material than the stitched crepe paper product of U.K. Patent No. 1,422,940. This product is thicker, and has greater depth in the gaps between the stitches 10 thus making the product more suitable for adhering to other materials in forming laminates since better anchor points of adhesive can be formed. In addition this product has, as already noted, greater lateral flexural rigidity.

One example of a composite sheet material made by the method of the present invention using a crepe paper sheet material will now be described with reference to Figure 7 of the accompanying drawings. A preferred method of making this product using the 20 crepe paper base sheet material is identical with the method described hereinbefore with reference to Figures 1 to 5 in relation to a plain paper sheet material.

In Figure 7 of the accompanying drawings the 25 crepe paper is denoted by the reference numeral 22 and a greater length of the crepe paper 22 than the length of a stitch 7 is contained within each stitch 7. A weft thread 20 is substantially covered and is largely obscured from view by the deformed roll or crinkle 19 30 in the crepe paper within each stitch.

In Figure 7 a break is shown in the crepe paper 22 in order to represent the hole formed in the crepe paper by the action of the needle in forming the stitch 7 through the crepe paper 22. 22 7 3 3 4 Good results have been obtained using crepe papers formed by reducing the lengths of plain paper, for example of 40 grammes weight per square metre, by about 507o and about 757o.

The product of Figure 7 has a substantially increased thickness as compared with the product of U.K. Patent No. 1,422,940 and is very much bulkier due to the longer lengths of the crepe paper which are trapped in the stitched loops giving a clear ridge 10 effect running transversely and distinguishing the product visually from the product of U.K. Patent No. 1,422,940.

As a result of the greater surface area of crepe paper trapped per stitch, the product of Figure 7 15has a potential for increased adhesion properties as compared with the product of both U.K. Patent No. 1,422,940 and the product of Figure 6. The product of Figure 7 also has an enhanced ability to be stretched longitudinally after stitching. It is found that 20whereas a product of U.K. Patent No. 1,422,940 may be stretched only to about 1.4 times its original length before the paper component tears, and the product of Figure 6 may be stretched to about twice its original length, the product of Figure 7 may be stretched to 25about 2.2 times its original length. This additional stretching ability is due to the presence in the product of both the initial paper crimp and the gross crimp resulting from the method of the present invention.

The freedom to apply a higher stretch enables 30the production of a final product of enhanced longitudinal dimensional stability.

The product of Figure 7, either as formed in the method claimed in co-pending Application No. 218042 or with additional subsequent stretching, may be 0 2 7 3 3 4 employed, for example, as a carpet underlay base fabric, a secondary carpet backing, a wall covering, or as a table covering.

As one alternative to the method described with 5 reference to Figures 1 to 5, means may be provided for overfeeding the sheet material, for example either plain paper or crepe paper, by advancing it at a rate such as to create a quantity of slack sheet material which is moved by the needles without the needles 10 piercing the sheet. The needles may then be of any profile, for example sharply pointed. When the movement of the sheet material by the needles is restrained, the needles pierce the sheet material and form the stitch through the sheet material thereby entrapping, 15 within each stitch in each longitudinal row of stitches formed in the sheet material, a portion of sheet material having a length greater than the length of the completed stitch.

As another alternative method, instead of 20 positively overfeeding the sheet material in order to create a quantity of slack sheet material in the region of the needles, the feed roll may be free of any braking or other restraining mechanism so that slack sheet material is readily made available by 25 the action of needles of any profile without piercing of the sheet material.

Any of the methods described may be employed in the manufacture of a composite sheet material in accordance with the present invention by stitching 30 together two or more sheets of sheet material. One example of a composite sheet material including two sheets of sheet material will now be described with reference to Figure 8 of the accompanying drawings.

In Figure 8 there is shown a portion of a 22 7 3 3 4 composite sheet material including two sheets of paper sheet material which may be either both plain or both crepe or any combination of plain and crepe paper sheet materials. An increase in the length of the 5 upper paper sheet material 23 entrapped within each stitch 24 has been created by one of the methods previously described while the lower paper sheet material 25 has been retained under tension so that there is no increase in the length of the lower paper 10 sheet material 25 entrapped within each stitch 24. The composite sheet material illustrated in Figure 8 is made using sharply pointed needles to pierce the lower paper sheet material 25 while the upper paper sheet material 23 is either positively overfed or 15 is provided from a feely rotatable feed roll so that the sharply pointed needles will raise the upper paper sheet material 23 until this upward movement by the needles is restrained by the sinker unit when the needles will pierce the upper paper sheet material 23 20 and thereafter form the stitch 24 which entraps the increased length of the upper paper sheet material 23 above the weft yarn 26 which has been laid on the surface of the upper paper sheet material 23.

The product of Figure 8 may be made from sheet 25 materials other than paper sheet materials, for example sheets of plastics film may be employed.

The product of Figure 8 may also be subjected to hot-stretching, as a result of which a product with excellent dimensional stability is produced with 30 a greater economy in the quantity of sheet material used than occurs in the manufacture of the un-stretched product of Figure 8.

Claims (7)

m 227334 WHRT^f/WE CDttM IS:- -16-

1. A composite sheet material comprising a sheet material having a longitudinal series of laterally extending deformed tubular ribs formed therein, the 5 ribs being entrapped within and deformed by a series of side-by-side longitudinally extending rows of stitches formed in the sheet material, and a series of weft yarns, each weft yarn being laid adjacent to a laterally extending deformed tubular rib and 10 being at least partially obscured by the adjacent laterally extending deformed tubular rib.

2. A composite sheet material comprising a plurality of sheets of sheet material, a series of side-by-side longitudinally extending rows of stitches which extend 15 through the plurality of sheets of sheet material, one of the sheets of. sheet material having a longitudinal series of laterally extending deformed tubular ribs formed in an exposed surface thereof and the ribs being entrapped within and deformed by 20 the longitudinally extending rows of stitches, and a series of weft yarns, each weft yarn being laid adjacent to a laterally extending deformed tubular rib and being at least partially obscured by the adjacent laterally extending deformed tubular rib. 25

3. A composite sheet material according to Claim 1 or Claim 2 wherein the sheet material in which the ribs are formed is a sheet of plain paper.

4. A composite sheet material according to Claim 1 or Claim 2 wherein the sheet material in which the 30 ribs are formed is a sheet of crepe paper. as claimed in Claim 1,

5. A composite sheet material / substantially as^-— N hereinbefore described with reference to Figu£% r* o 'I - % "^3 0 JUN1989'";/' (few 4 -17- 227334 of the accompanying drawings. as claimed in Claim 1,

6. A composite sheet material/ substantially as hereinbefore described with reference to Figure 7 of the accompanying drawings. as claimed in Claim 2, 5

7. A composite sheet material/ substantially as hereinbefore described with reference to Figure 8 of the accompanying drawings. BALDWIN. SON & CAREY a^9^:^ppucantS