PH27070A - Method of apparatus for making patterned belt bonded material - Google Patents

Description

, . CE “fof = : ! MeBion Ce 0 RATS Gd PARLHG EA or rr Tin aL,

Background of the Invention

Honeycomb currently markets an apparatus for heating and fusing thermoplastic fibers in a web. The apparatus is a modification of their thru-air bonder for drying and heat setting fibrous webs. In this apparatus, the web is i 10 carried about a rotating drum and heated air is blown onto the web. When starting with a high loft, low density web, such an apparatus yields a very high loft, low density fabric having limited strength. Copending Application No. (CHIC-653) discloses an apparatus and method wherein the web is carried about an open mesh structure which is substituted for the surface of the drum. This apparatus and method produces a unique fabric having patterned v regions of even higher loft where fibers are bent out of the plane of the fabric. Another method and apparatus for heat fusing thermoplastic fibers in a web set forth in copending Application No. (CHIC-654), the web is picked up ! by a first carrier belt, a second carrier belt is placed on top of the web and the double belt laminate is passed about heated rolls. A fabric made by the double belt bonder has good strength including good cross directional strength but is more dense and not as lofty as fabric made on the Honeycomb apparatus.

Summary of the Invention

The present invention comprises a method and apparatus for forming a fabric from a web comprising at least five per- cent low shrink thermoplastic fibers including conjugate fibers and the fabric formed thereby. The method com- prises heating a web comprising said low shrink thermo- plastic fibers to heat fuse the fibers in the web while

CHIC 655 . — - -

BAD ORIGINAL 2

Go oye

Poo v -2~ v the web is tensioned between a first carrier belt and an open nesh belt. When conjugate fibers are used, the method comprises fusing at least the low melting point component of the conjugate fibers. The apparatus of the present invention comprises heating means, a first carrier belt and means for causing said belt to travel in an arcu- ate path adjacent the heating means, an open mesh belt and means for causing said open mesh belt to travel along an initial path spaced from said first carrier belt and then along said arcuate path. The fabric formed by the method and apparatus of the present invention has a surface pat- tern on at least one surface thereof and patterned densi- . fied regions which are created by the open mesh belt. The fabric has high loft and low density as well as good strength. The open mesh belt may be overlaid by a second carrier belt sandwiching the web and open mesh belt \ between two carrier belts. The first carrier belt may comprise a second open mesh belt to form a fabric with a : pattern on both surfaces. The strength, cushioning, and absorbency of the fabric make it attractive for many end ' uses including as a diaper facing material. When used as a diaper facing, the fabric may comprise hydrophobic fibers. When only one surface of the fabric is patterned, the fabric displays a greater porosity on the patterned side and a lesser porosity on the unpatterned side providing enhanced wicking from the patterned surface and minimize strike back when used as, for example, a diaper : facing.

Brief Description of the brawings

Figure 1 is a schematic side view of one embodiment of the apparatus and method to the present invention.

Figure 2 is a plan view of a portion of the open mesh belt for use according to the present invention.

CHIC 655

: A Po . : -3- <

Figure 3 is a perspective view of one embodiment of a fabric according to the present invention.

Figure 3A is a fragmentary section of the fabric of Figure 3 illustrating schematically how the fabric was formed.

Figure 4 is a perspective view of another embodiment of a fabric according to the present invention.

Figure 4A is a fragmentary section of the fabric of Figure 4 illustrating schematically how the fabric was forned. : . Description of the Drawings

The present invention comprises an apparatus and a method for making a fabric from a web comprising low shrink . thermoplastic fibers, including conjugate fibers and the fabric formed thereby. It is preferred to employ sheath/ core conjugate fibers of polyethylene/polyester respec- tively. Sheath/core fibers of polyethylene/polypropylene ' may also be used, as well as low shrink thermoplastic such as Eastman 4BC crystalline copolyester monofil. Either : eccentric or concentric sheath/core fibers can he employed. }

Figure 1 illustrates, schematically, a side view of one embod inent of the apparatus of the present invention wherein the heating means comprises heated rolls or stean cans. Alternate heating means, such as a Honeycomb apparatus, may be used, including any other heating means where the belts can travel in tensioned arcuate paths adjacent the heating means.

In the method shown, a first endless carrier belt 3, is provided having means 5, for causing said first endless carrier belt to travel in a curvilinear path 6, adjacent

CHIC 655

< the heating means. Web 7 is superimposed on said first carrier belt 3. In its broadest aspect, the present invention includes the surface of a Honevcomb type dryer as the first endless carrier belt.

According to the present invention, an open mesh belt 9 is superimposed on the web prior to heating. The open mesh structure may comprise an endless belt provided with means 11 for causing said open mesh belt to travel along an initial path 13 spaced from said first endless carrier belt, and then along the curvilinear path 6 around the heating means. A second endless carrier belt 15 may be superimposed on top of the open mesh structure 9. When a second endless carrier belt is used, the open mesh belt may comprise belt segments. The second endless carrier belt is provided with means 17 for causing said belt to . travel along path 6. The conjugate fibers in the web, when heated, fuse to fibers in the web to provide a strong, high loft, low density fabric. , In a preferred embodiment of the method of the present invention the web is cocled before it is separated from . the first carrier belt and the open mesh belt. To facilitate cooling, the belts may be passed around at least one cooling roll shown at 19 in Figure 1. By maintaining the web between the belts until the web is cooled, the method avoids the loss in cross directional strength due to drafting as a web is removed from a roll on one carrier belt. Also the use of the two belts prevents sticking of the heated thermoplastic fibers of the web to the rolls and permits rapid handling of the web while heated, including immediately passing the web about cooling rolls.

Figure 2 illustrates a portion of an open mesh belt 20 used in the present invention. The open areas 22 and

CHIC 655

Lo i po | ofele -5- : ‘ depth 24 of the open mesh belt allow the web to maintain its high loft and low density through the heat bonding procedure. The depth 24 of the open mesh belt maintains the distance between the tensioned first and second carrier belts so that the web is not crushed therebetween.

The depth of the open mesh belt and the dearee of open area 22 determine the loft of the final fabric material.

Figure 3 illustrates a fabric formed according to the method of the present invention. As shown in Figure 3A, the fabric is formed using one open mesh structure as seen in Figure 2. The fabric shown generally at 30 has one surface thereof 32 which is patterned. The surface 32 consists of regions 34 of high loft, low density and good porosity and regions 36 that are densified between the open mesh structure 20 and carrier belt 3. Surface 38 formed against belt 3 is smooth. The fabric has a . porosity differential from the surface 32 to the opposite surface 38 and hence may be used advantageously in many applications, for instance, as a diaper facing fabric.

The fabric formed according to the method of the present ’ invention exhibits a high loft, lower density and better ‘ strength than fibers formed on a double belt bonder as described in copending application (CHIC 654) or with a thru-air bonder. }

In the following example, samples of a web formed with a dual rotor were fusion bonded according to the methods listed.

CHIC 655

Nh. = -6- 4

Example 1

PRESENT DOUBLE-

THRU-AIR ~~ INVENTION CELT

Weight oz/yd.? 3.0 3.1 3.2

Bulk inch .066 .060 .042

Density gm/cm3 .0613 .0694 .1002

Tensile 1b. 1.0 1.5 1.8

Tenacity lb./inch/100 grains .08 11 .13 10 . Absorbency % 1329 1155 896

Rate sec 3.1 3.1 9.9

Softness MD gram 135.5 133 162.7

CD gram 85.1 112 162.8

As can be seen, the fabric formed according to the present invention maintains a high bulk and lov density similar to that of the thru-air bonder but has a strength approxi- * mately that of a double belt bonded fabric. webs used in the present invention may be prepared by air laying or carding of the fibers. The weight of the web may range from 0.3 to 5 ozs./yd.?. The present invention preferably utilizes a conjugate fiber with an outer sheath of thermoplastic material. In a most preferred embodi- ment, the fiber. is capable of self-crimping when heated and the method involves heating to effect autogenous bond- ing of the web and self-crimping of the thermoplastic fibers. The web may further comprise synthetic wood pulp, wood pulp, cellulosic or other fibers. The percentage of the low shrink thermoplastic fibers in the web may vary from five to 100 percent.

CHIC 655 yoo I

Le So offen -7- s The open mesh belt is preferably formed of a material with easy release properties and/or good heat transmission.

The structure of the open mesh belt may vary according to the desired properties of the fabric; the more open mesh vielding more bulk, softness and absorbency; the tighter mesh yielding higher tensile strength as set forth in the following Example.

Example 2 . 10 Mesh = 3.0 4.7 5.3 5.8 6.0 6.8

Weight oz/yd.? 3.1 3.2 3.1 3.3 3.1 3.2

Bulk inch .060 .062 .060 .058 .053 .056

Density gm/cm?3 .0694 .0682 .0694 .0758 .0736 .0756

Tensile MD 1b. 1.5 1.7 1.5 1.8 1.8 1.8

Tenacity lb/ 11 .12 11 .12 .13 .13 inch/100 grains

Absorbency % 1155 1219 1 1155 1070 1038 1062 .

Rate sec 3.1 2.9 3.1 4.0 3.8 4.3

Softness:

MD gram 133 162.6 132.7 143.9 154.9 152.1

CD gram 112 109.5 112.4 138.6 123.1 129.7

Figure 4 illustrates another fabric formed by the method and apparatus of the present invention. As shown in

Figure 42, another open mesh belt is. substituted for the first carrier belt or interposed between the first carrier belt and the web. The fabric is shown generally at 40.

Both surfaces 42 and 44 of the fabric have a surface pattern. As the surfaces 42 and 44 are formed by means of separate open mesh belts 3' and 9, they need not have the same pattern and may be formed by different open mesh belts and belts out of registrv. Each of the surfaces 42 and 44 have regions 46 of high bulk and low density and good porosity and regions 48 that are densified. Though the fabrics made according to the method of the present invention. have many uses, they are particularly suited for those end uses requiring strength, bulk and absorbency.

CHIC 655

Claims (7)

Co. 9 | | : -— 1S - ~ 27070 I CLAIM:

1. Apparatus for forming a nen-woven fabric compris- ing thermoplatic fibers, said apparatus comprising: ta) a frame; (v3 first and second heated rolls rotatably mounted to said frame in cofiset relationship to each other, said rolls being spaced apart a sufficient distance to avoid a compression nip between said first and second rolls: : (c) a first endless carrier helt means mounted to said frame for travel in a path consscutively around substantial porticns of said first and second heated rolls; td) a second endless carrier belt means mounted to , eaid frame for travel along said path around substantial portions of said first and second heated rolls adjacent to said first helt means: (ee) at. least one of said carrier belt means having an open mesh structure formed by spaced, intersecting mesh elements so as to define open areas between said mesh elamente: (f) means for superimposing oo fibrous web, comprie- ing at least © percent thermoplastic fibkers, onto said J first belt means so that said first =and second belt means form a two helt laminate with said web sandwiched there- between, said two hall laminate being caussd Lo travel in said path consecutively =zrcund a substantial portion of eaid firet heated roll tc initially =zpply hest to a first cide of =aid web and thorehy fuse =t least the termoplas- tic fibers adjacent to said mesh elesmente to fibers ad- BAD OR!ICINAL 9d

> g . 29] - 9 = jacent the first cide therecf and then around a substan- : tial portion of said second heated roll to apply heat to a second side of said web and thereby fuse at least the thermoplastic fibers adjacent to said mesh elements to fibers adjacent the second side thereof. sc as tc form a web having a patterned surface defining regions corresponding to the open areas between said mesh elements that substantially maintain the high 1lcft end and low density of the web that are bordered by fused regions corresponding to the mesh elements; (g) the perirheral surfaces of said first and second heated rolls cooperating to provide a portion of said path whereby said two belt laminate travels cut of contact with said first and second heated rolls: and (h) means for cooling said two belt laminate after ' it has travelled around said first and second heated rolls x to copl the fibers in the web sandwiched between said first and second endless carrier belts.

2. Apparatus as set forth in claim 1. wherein said cocling means comprises at least one cooling roll.

3. Apparatus as set forth in claim 1, wherein third and fourth heated rolls are mounted to said frame in offset relationship tc each other, said third and fourth rolls being spaced apart a sufficient distance to avcid a compression nip between said first and second reclls.

4. Apparatus as set forth in claim 1, wherein said third roll is spaced vertically above said first rcll and zaid fourth roll is spaced vertically above said second roll.

. [ee . - 10 -

5. Apparatus as set forth in claim 3. wherein a further endless carrier belt means is mounted to said frame for travel along said path in superimposed relation- ship upon the carrier belt means having said open mesh structure.

8. Apparatus as set forth in claim 1, wherein said first and second endless belt carrier means both have an open mesh structure defined by intersecting mesh elements.

7. Apparatus as set forth in claim 6. wherein the mesh elements of said first endless helt carrier means are aligned with the mesh elements cof said second endless belt carrier means as said first and second endless helt car- rier means travel along said path. ALFRED T. MAYS / Inventor ,