MXPA99005816A - Lamination of breathable film using a rubber-covered anvil roll - Google Patents

Abstract

The present invention relates to a process for producing an improved film/nonwoven laminate from a fibrous nonwoven web and a polymeric film wherein the nonwoven web and polymeric film are bonded together by passing the nonwoven web and the polymeric film through the nip between two rolls. One of the rolls is in contact with polymeric film. This roll has a surface that is made from a soft material that deforms under nip pressure.

Description

BREATHABLE FILM LAMINATION USING A RUBBER COATED ANODE ROLLER FIELD OF THE INVENTION The present invention relates to a process for laminating a breathable film using a yunker roller covered with a soft material. The invention also refers to the product produced therewith.

BACKGROUND OF THE INVENTION The present invention relates to a nonwoven laminate d / breathable film having an improved roughness (elongation) and a greater retention of barrier properties. The present invention also relates to the process for producing the same using an anvil roller covered with a soft material.

Laminated materials have a wide variety of uses, especially in the areas of absorbent articles and disposable articles. As used herein, the term "absorbent articles" refers to devices which absorb and contain body exudates and, more specifically, refer to devices that are placed against or in proximity to the user's body. absorb and contain the various exudates discharged from the body. The term "absorbent articles" is intended to include diapers, underpants, incontinence devices and the like. The term "disposable" was used herein to describe absorbent articles not intended to be washed or otherwise restored or reused as an absorbent article.

Film / nonwoven laminates can be produced using thermal point bonding. The thermal point union traditionally involves passing the tissues that are to be joined together through the pressure point of two steel rollers. Generally, one of the steel rollers is engraved or embossed, with a pattern. This roller is known as the "pattern roller". The non-engraved roller is known as the "anvil roller". During the rolling process, the pattern on the patterned roller is imparted to the laminated fabric. The use of steel anvil rollers tends to result in severe deformation of non-woven fibers, resulting in a weak laminate.

There is therefore a need for a method for producing a film / nonwoven laminate having improved strength without causing severe deformation to the non-woven fibers.

SYNTHESIS OF THE INVENTION It has been found that lamination of the breathable film using an anvil roller covered with a soft material produces laminations in the severe deformation of the non-woven fabric that frequently results from using two steel rolls. This reduced deformation of the non-woven fabric results in a laminate with improved tensile properties and improved rolling elongation. The elongation of greater laminate is important because it dictates a more resistant material, for example, one that is able to withstand pulling even more before breaking. The process of the present invention also maintains the integrity of the film through the complete bonding process.

The lamination process of the present invention requires a patterned roller, an energy source and an anvil roller that is covered with a soft material that deforms under the pressure of the fastening point but also has an adequate operational life.

The laminated materials produced according to the present invention can be used in absorbent articles for personal care and in surgical suits and covers and other forms of protective clothing such as laboratory suits and work clothes. The film / nonwoven laminates produced in accordance with the present invention are especially useful in the outer covers of absorbent articles for personal care, particularly diapers.

The foregoing and other features and advantages of the present invention will become apparent from the following detailed description of the currently preferred embodiments, when read in conjunction with the accompanying examples.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective and fragmentary view of a film laminate / not built in accordance with the present invention.

Figure 2 is a schematic side view of the rolling process of the present invention.

Figure 3 is a partially sectioned top view of an exemplary disposable garment which may use the laminate produced according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED INCORPORATIONS The present invention is directed to the lamination of non-woven fabrics and breathable film using an anvil roller covered with a soft material.

Referring now to the drawings in which like reference numbers represent the same or an equivalent structure, and in particular, Figure 1 of the drawings, there is illustrated a film / non-woven laminate 10 produced according to the present invention. The laminate 10 includes a fibrous nonwoven fabric 12 and a polymeric film 14 bonded thereto.

The fibrous nonwoven fabric 12 can be, for example, fabrics bonded with narrow polypropylene yarn, bonded with crimped, carded and bonded polypropylene yarn, meltblown or elastomeric yarn fabrics produced from elastomeric resins. Fibrous non-woven fabrics can impart additional properties such as a softer and more cloth-like feel to the polymeric film. A further cloth-type feel is particularly advantageous when the film is being used as a barrier layer in, for example, outer covers for absorbent articles for personal care, surgical gowns and covers, lab suits and other forms of protective clothing.

The manufacture of fibrous non-woven fabrics is known. Such fabrics can be formed from a number of processes including, but not limited to, spinning and meltblowing processes.

Meltblown fibers are fibers formed by extruding a melted thermoplastic material through a plurality of thin, usually circular, capillary vessels of a meltblown matrix such as melted threads or filaments into gas streams (e.g., air). ), usually hot and at high speed and converging which are flowing in the same direction as the extruded filaments or threads of the melted thermoplastic material so that the extruded filaments or strands are attenuated, for example, pulled or extended, to reduce their diameter. The yarns or filaments can be attenuated to a microfiber diameter which means that the yarns or filaments have an average diameter of no more than about 75 microns (μm), generally from about 0.5 microns to about 50 microns, and more particularly from about 2 microns to about 40 microns. Then, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collector surface to form a meltblown fabric and randomly disbursed. The meltblowing process is well known and is described in several patents and publications, including the 4364 naval research laboratory report, "Manufacturing of Super Fine Organic Fibers" by B.A. endt, E.L. Boone and D.D. Fluharty; the naval research laboratory report 5265, "An Improved Device for the Formation of Super Fine Thermoplastic Fibers" by K.D. Lawrence, R.T. Lukas and J.A. Young; U.S. Patent No. 3,676,242 issued to Prentice; and U.S. Patent No. 3,649,241 issued to Buntin et al. The above references are incorporated herein by this reference in its entirety. The meltblown fibers and microfibers which may be continuous or discontinuous, are generally smaller than 10 microns in average diameter and are generally sticky when deposited on a collecting surface.

Preferably the fibrous nonwoven fabric is bonded with polypropylene yarn. Spunbonded fibers are small diameter fibers that are formed by extruding a melted thermoplastic material as filaments from a plurality of usually circular and thin capillary vessels of a spinner organ with the diameter of the extruded filaments then being rapidly reduced such as by , for example, bonding mechanisms with non-eductive or eductive spinning yarns or other well-known ones. The production of non-woven spunbonded fabrics is illustrated in the patents such as, for example, U.S. Patent Nos. 4,340,563 issued to Appel et al .; 3,802,817 issued to Matsuki and others; 3,692,618 issued to Dorschner et al .; 3,542,615 granted to Dobo; 3,502,763 granted to Hartman; 3,502,538 issued to Peterson; 3,341,394 and 3,338,992 granted to Kinney; 3,276,944 granted to Levy; and Canadian patent number 803,714 granted to Harmon. The descriptions of these patents are incorporated herein by reference in their entirety. Spunbonded fibers are generally not sticky when deposited on a collecting surface. Spunbonded fibers are generally continuous and have average diameters (from a sample of at least 10) larger than 7 microns, and more particularly from about 10 microns to about 20 microns.

For the film 14 which is laminated to the non-woven fabric 12, a wide variety of thermoplastic films are useful. Such films include, but are not limited to polypropylene and / or polyethylene-based polyolefins in mono- or co-executions. Polypropylene films are preferred for lamination to polypropylene spunbonded.

A process for forming a polymer film 14 is shown in Figure 2 of the drawings. Referring now to this Figure, the polymeric film 14 is formed of an extrusion film apparatus 20 such as a blow or setting unit. Typically, the apparatus 20 includes an extruder 22. The polymeric material is prepared in a mixer 24 and is directed to the extruder 22. The film 14 is extruded into a pair of pressure point rolls 26 and 28 one of which can be pattern to share an engraving pattern to the newly formed film 14.

From the extrusion film apparatus 20, the film 14 is directed to a film stretching unit 30 such as a steering guidance machine which is commercially available from vendors such as The Marshall and Williams Company of Providence, Rhode Island. Such an apparatus 30 has a plurality of stretching rollers 32 that move at progressively faster speeds relative to the pair disposed before it. These rollers 32 apply a quantity of tension and therefore progressively stretch the film 14 to a second length in the machine direction of the film which is the direction of movement of the film 14 through the process as shown in the Figure 2. The stretching rollers 32 can be heated for better processing. The film stretching unit 30 may also include the rollers (not shown) facing up and / or downward of the stretching rollers 32 which can be used to preheat the film 14 before orienting and / or to cool the film 14 after stretch it.

Preferably, the second or stretched length e from about two to about six times, more preferably from about three times to about four times the original length of the film 14 before stretching.

The film 14 is then directed away from the stretching unit 30 so that the tension is removed and the film 14 is allowed to relax. Preferably, a permanent elongation length of from about 1.5 times the original length is retained after the stretched film is allowed to relax.

The lamination reinforces and protects the film. During the lamination process, the film 14 is attached to the non-woven fabric 12 to form a laminate 10.

Referring again to Figure 2, a side view of the lamination process of the present invention is also illustrated. A conventional fibrous nonwoven fabric forming apparatus 40, such as a pair of spinning knitting machines, was used to form the fibrous nonwoven fabric 12. The essentially continuous long fibers 42 are deposited on a forming wire 44 as a fabric unattached 46. Unbound fabric 46 is then sent through a pair of nip rolls 48 and 50 to join the fibers together and increase the tear strength of the resultant fabric 12. One or both of the rolls 48 and 50 they are frequently heated to aid in the joint. Typically, one of the rollers 48 and 50 also has a pattern such as to impart a discrete bonding pattern with a prescribed bonding area to the fabric 12. The other roll is usually a smooth anvil roll but this roll may also have a a pattern if desired. As used herein, the term "smooth" means that the roller does not have a pattern.

Once the film 14 has been stretched sufficiently and the fibrous nonwoven fabric 12 is formed, the two layers are put together and laminated using the thermal point joint. The thermal point attachment involves passing the film 14 and the fibrous nonwoven fabric 12 through the pressure point formed between a pair of rollers 52 and 54. As with the bonding rolls 48 and 50, at least one of the rolling rolls has a pattern for creating a discrete bonding pattern on the resulting laminate 10. If desired, the bonding rolls 48 and 50 can be omitted or used for light compaction and the rolling pressure point between the rolls 52 and 54 can serve to simultaneously join the non-woven fabric 12 as well as to form the laminate 10. Generally, the maximum bonding surface area for a given area of surface on one side of the laminate 10 will not exceed about 50% of the total surface area. Any of a number of discrete union patterns can be used. The examples are described in U.S. Patent No. 4,041,203 to Brock et al., Which is incorporated herein by reference. The patterned roller 52 is a metal roller, preferably made of steel.

During lamination, the film is oriented against the non-engraved roller 54 which is also known as the anvil roller. Such orientation helps to force the distribution and prevents damage to the film before during the bonding process.

The anvil roller 54 is also made of metal, again preferably steel. The anvil roller 54, however, is covered with a soft material which deforms under the pressure of the clamping point but which also has an adequate operational life. The soft material generally has a surface roughness (R-) of about 5 to about 250. The surface roughness is measured with a surface roughness tester such as, for example, the Surftest 211 produced by MTI Corporation. The soft material should be softer and more conformable than steel such as rubber. Rubber-containing compounds can also be useful such as, for example, a silicone rubber compound with a Shore A hardness of about 80-95. Preferably, a sleeve (not shown) slides on the metal anvil roll 54 to provide the conformable and smooth surface.

The sleeve is deformed under the pressure of the rolling fastening point thus creating a larger area on which a constant pressure point force is distributed. This in turn results in a lower pressure required for the lamination. The pressure used during lamination according to the present invention is from about 170 to about 230 pounds per square inch (11.95-16.17 kilograms / square centimeter), depending on the relative softness of the sleeve covering the anvil roller 54. The lower pressure, even when it is sufficient to laminate the incoming film 14 and the non-woven fabric 12, eliminates the severe deformation of the non-woven fabric 12 which It usually occurs during lamination. The resulting laminate 10 also exhibits improved tensile properties and rolling elongation, thus indicating a more resistant laminated material.

Preferably, the power source used to assist in the lamination are infrared heaters. Other sources, such as an air knife can also be used. The temperature on the pattern roller 52 is between about 110 degrees centigrade and about 126.67 degrees centigrade. The anvil roll 54 takes heat and runs at about 65.57 degrees Celsius during steady state processing.

Once the laminate 10 comes out, it can be wound onto a roll 58 for subsequent processing. Alternatively, the laminate 10 can continue online for further processing or conversion.

The process shown in Figure 2 can also be used to create a three layer laminate. The only modification to the previously described process is to feed a supply 60 of a second fibrous non-woven fabric 12a to the patterned roller 52 and to the anvil roller 54 on the side of the film 14 opposite that of the other non-woven fabric 12. One or both of the non-woven fabrics 12 and 12a can be formed directly in line, as illustrated with the non-woven fabric 12 in Figure 2. Alternatively, one or both of the non-woven fabrics 12 and 12a can be formed in the shape of a preformed roll 62 as illustrated in Figure 2 by the non-woven fabric 12a. In either case, the second nonwoven fabric 12a is fed between the pressure point of the pattern roller 52 and the anvil roller 54 and is laminated to the film 14 in the same manner as the first fibrous nonwoven fabric 12.

As previously stated, the laminate 10 produced according to the present invention can be used in a wide variety of applications including absorbent articles for personal care such as diapers, training pants, incontinence garments, gowns and covers surgical and protective clothing such as lab coats and other work clothes. A disposable garment 70, in this case a diaper, is shown in Figure 3. Although the diaper is shown in Figure 3, it is understood that the use of the laminate 10 produced according to the present invention is not limited to such articles. and can also be used in a wide variety of applications. Referring again to Figure 3, the disposable garment 70 includes a liquid-permeable top or liner sheet 72, an outer cover or lower leaf 74 and an absorbent core 76 positioned between and contained by the liner 72 and the outer cover 74. Disposable garment 70 may also include some form of fastening means 78 such as adhesive fastening tapes or mechanical hook-and-loop type fasteners and stretched region 80.

The laminate 10 can also be used to form various parts of the disposable garment 70 including, but not limited to the liner 72, the outer cover 74 and the stretch region 80. Preferably, the laminate 10 is used to form the outer cover 74 of the disposable garment 70.

The advantages and other features of the present invention are better illustrated by the following examples. It should be understood that the following examples are non-limiting illustrative.

Two sets of film / spunbonded laminates were produced using the steel and rubber anvil rollers. The laminates bonded with the rubber anvil roller exhibited a greater elongation compared to the laminates bonded with the steel anvil roller. An analysis of the resulting laminates by electron microscope examination indicated that the increase in elongation in the laminate material with the rubber anvil roller is due to the fact that the fibers joined with spinning in the area of the junction points in those Materials were flattened and indented in the film rather than melting into the film as shown in the samples attached with the steel anvil roller.

Claims (17)

R E I V I N D I C A C I O N S

1. A process for preparing an improved nonwoven / film laminate comprising the step of joining together a fibrous nonwoven fabric and a polymeric film by using a power source to heat the laminate and passing said fibrous nonwoven fabric and said polymeric film through the point of pressure between two rollers, where the surface of only one of the rollers is made of a soft material that deforms under the pressures of the pressure point of 170 to 130 pounds per square inch (11.95-16.17 kilograms / square centimeter) and the other roller is a metal surface roller.

2. The process as claimed in clause 1 characterized in that said soft material is selected from the group consisting of rubber and rubber-containing compounds.

3. The absorbent article for personal care comprising a liquid permeable liner and an outer cover with an absorbent core positioned therebetween, wherein said outer cover includes the laminate made of film as claimed in clause 2.

4. The absorbent article for personal care as claimed in clause 3, characterized in that said article is a diaper.

5. The absorbent article for personal care as claimed in clause 3, characterized in that said article is a training underpants.

6. The absorbent article for personal care as claimed in clause 3, characterized in that said article is an incontinence garment.

7. A personal protective garment comprising a liquid permeable liner and an outer cover, wherein said outer cover includes a film laminate made as claimed in clause 2.

8. The protective garment as claimed in clause 7 characterized in that said article is a lab coat.

9. The protective garment as claimed in clause 7 characterized in that said article is protective workwear.

10. A process for producing an improved film / nonwoven laminate comprising the steps of: forming a fibrous nonwoven fabric; providing a polymer film having an original length and being capable of having a stretch length at room temperature that is at least about two times said original length and an immediate release length essentially equal to said original length; stretching said polymer film to form a film having a second length; allowing said film to relax, thereby producing a film having a third length; Y passing said fibrous nonwoven fabric and said polymeric film through the pressure point between two rollers, wherein one of said rollers is covered with rubber or a rubber-containing compound so that the surface of said roller is smooth.

11. The process as claimed in clause 10 characterized in that said fibrous nonwoven fabric is selected from the group consisting of spun bonded polypropylene, crimped polypropylene bonded with spinning, bonded carded fabrics, meltblown fabrics and elastomeric yarn bonded produced from elastomeric resins.

12. The process as claimed in clause 11 characterized in that said fibrous nonwoven fabric is a polypropylene linked with spinning.

13. The process as claimed in clause 10 characterized in that said polymeric film is selected from the group consisting of polypropylene and / or polyolefins based on polyethylene.

14. The process as claimed in clause 13 characterized in that said polymer film is a polypropylene film.

15. A process for producing an improved film / nonwoven laminate comprising the steps of: forming a fibrous nonwoven fabric; providing a polymer film having an original length and being capable of having a stretched length at room temperature that is at least about two times said original length and an immediate release length essentially equal to said original length; stretching said polymer film by applying a quantity of tension to produce a film having a second length that is from about two times to about six times said first length; removing said tension amount from said polymer film to produce a film having a third length that is about 1.5 times said first length; Y passing said fibrous nonwoven fabric and said polymeric film through the point of pressure between two rollers, one of said rollers is in contact with said polymeric film having a smooth surface, wherein said surface of said roller is both smooth and is made of a soft material that deforms under the pressure of the fastening point.

16. The process as claimed in clause 15 characterized in that said soft material is rubber or a rubber-containing compound.

17. The process as claimed in clause 16 characterized in that the second length is from about three times to about four times said original length. SUMMARY The present invention relates to a process for producing an improved film / nonwoven laminate of a fibrous nonwoven web and a polymeric film wherein the nonwoven web and the polymeric film are bonded together by passing the non-woven fabric and the polymeric film through the pressure point between two rollers. One of the rollers is in contact with the polymeric film. This roller has a surface that is made of a soft material that deforms under the pressure of the clamping point.