KR0158457B1 - Non-woven web and method of forming the same - Google Patents

Abstract

Nonwoven webs for barrier layer applications are specified in SMS fabric laminates. The web is formed at commercial polymer melt emissions (greater than 3 PIH) by using reactor granulated polyolefins, preferably polypropylene, and modified by the addition of up to 3000 ppm of peroxide, resulting in an initial molecular weight distribution of 2.2 to 4.0 to 4.5 Mw / Mn. Reduce to the range of 3.5 Mw / Mn. In addition, peroxide is added to increase the melt flow rate (lower viscosity) in the range of 800 to 5000 g㎳ / 10 min at 230 ° C. The resulting web has an average particle size of 1 to 3 microns, a pore size mainly distributed within 7 to 12 microns, a small amount of pores of 12 to 25 microns, substantially no pores exceeding 25 microns and a peak of pore size distribution. Less than 10 microns.

Description

Nonwoven web with improved barrier properties

1 is a schematic diagram of a former for use in the manufacture of a nonwoven laminate comprising a meltblown barrier layer of the present invention.

2 is a cross-sectional view of the nonwoven laminate of the present invention showing a layer arrangement comprising an inner meltblown barrier layer made by the present invention.

3 shows a meltblown web (Sample 1) produced by the present invention, an SMS fabric laminate (Sample 2) incorporating the meltblown web as a barrier layer, a typical meltblown web (Sample 3), and conventional Graph showing pore size distribution for SMS fabric laminate (Sample 4).

* Explanation of symbols for main parts of the drawings

10: Forming Machine 12: SMS Fabric Laminate

14; Forming Belt 16,18: Roller

20,24: spun bonding station 22: melt blowing station

26: spun adhesive filament 28,36: spun adhesive nonwoven web

30: micro fiber 31: die

32: melt blown barrier layer 34: spun adhesive filament

38,40: adhesive roll 41: separated area

The present invention generally relates to nonwoven webs having a small pore size distribution with fine fibers and methods of forming such webs. The process of the present invention employs reactor granule resins initially having a wide molecular weight distribution, whose molecular weight is distributed within a narrow range and modified to increase its melt flow rate. As a result, the nonwoven web can be formed by melt blowing with a high raw material amount. Such nonwoven webs are particularly useful as barrier layers for woven laminates.

Nonwoven laminates have a wide range of applications. Such nonwoven laminates are useful for wipers, towels, industrial garments, medical garments, medical drapes, and the like. Disposable fabric laminates have been used extensively in drapes, gowns, towels, foot covers, sterile wraps and the like, especially in hospital operating rooms. Such surgical fabric laminates are typically spun adhesive / meltblown / spun adhesive (SMS) laminates that consist of a nonwoven layer of spun adhesive polypropylene on the outside and a barrier layer of meltblown polypropylene on the inside. In particular, Kimberly-Clark Corporation, the assignee of the present invention, has been a trademark of Spunguard for many years. ) And Evolutin Surgical SMS Nonwoven Laminate has been manufactured and marketed. Such SMS fabric laminates have a durable spun adhesive layer on the outside and a meltblown barrier layer that is porous on the inside but inhibits the passage of fluid from the outside to the inside of the fabric laminate. In order for such surgical fabrics to be used properly, the meltblown barrier layer needs to have a fiber size and a pore size distribution that provides breathability to the fabric and prevents the passage of fluid.

Kimberly-Clark Evolution Meltblown webs used in the manufacture of medical fabric laminates have a pore size whose peaks in the pore size distribution are greater than 10 microns and are predominantly distributed in the range of 10 to 15 microns. Such meltblown webs have advantages as barrier layers, but have average fiber sizes of 1 to 3 microns, pore size distribution peaks of less than 10 microns, and most voids range from 7 to 12 microns. The use of meltblown webs can further improve porosity and passthrough inhibition. More specifically, the pore size of the meltblown web is measured in the Coulter Porometer, mainly in the range of 7 to 12 microns, with a small amount of pores in the range of 12 to 25 microns and in excess of 25 microns. When substantially free of silver, the properties regarding porosity and passage can be improved. Therefore, it is an object of the present invention that the average fiber diameter is in the range of 1 to 3 microns and the pore size is predominantly in the range of 7 to 12 microns, and the small amount of pores are in the range of 12 to 25 microns, and the pores are greater than 25 microns. Is substantially free and has a peak of pore size distribution below 10 microns, providing a nonwoven web to be used as a barrier layer in a fabric laminate. It is also an object of the present invention that the pore size is mainly distributed in the range of 5 to 10 microns, the small amount of pores is 10 to 15 microns, substantially no pores exceeding 22 microns, and the peak of the pore size distribution melts It is to provide a non-woven laminate having a small pore size distribution and a barrier layer of fine fibers, down to 5 microns or less from the peak of a new web only.

The object is preferably obtained by forming a meltblown web from a resin having a wide molecular weight distribution and having a high melt flow rate, modified by adding a small amount of peroxide prior to processing to obtain a faster melt flow rate (low viscosity). . In general, the present invention starts with a polymer in the form of reactor granules, having a molecular weight distribution of 4.0 to 4.5 Mw / Mn and a melt flow rate of about 400 g㎳ / 10 min at 230 ° C. This molecular weight reactor granular polymer was then modified such that the distribution of the molecular weight of the polymer was reduced and limited in the range of 2.2 to 3.5 Mw / Mn by adding up to 3000 ppm of peroxide. During the meltblowing process, the modified reactor granular polymer has an increased melt flow rate in the range of 800 to 500 g㎳ / 10 min at 400 g㎳ / 10 min at 230 ° C.

In particular, a polypropylene resin in the form of reactor granules having a starting molecular weight distribution of 4.0 to 4.5 Mw / Mn and a melt flow rate of 1000 to 3000 g㎳ / 10 min at 230 ° C. is combined with a small amount of peroxide of less than 500 ppm 5000 g㎳ / 10 min at 230 ° C. Modified polypropylene is produced having a very high melt flow rate of below and a narrower molecular weight distribution of 2.8 to 3.5 Mw / Mn.

Alternatively, the improved meltblown web for barrier layer applications has a narrower molecular weight distribution and a lower melt flow rate resin, specifically poly, modified by adding a large amount of peroxide prior to meltblowing to obtain a high melt flow rate. It can be formed using propylene. The starting reactor granular polypropylene resin has a molecular weight distribution of 4.0 to 4.5 Mw / Mn and a melt flow rate of 300 to 1000 gPa / 10min at 230 ° C. The polypropylene resin is modified by adding an amount of 500 to 3000 ppm of peroxide (higher amounts of peroxide are used at lower initial melt rates). The modified polypropylene resin has a melt flow rate of about 3000 g㎳ / 10 min or less at 230 ° C and a narrower molecular weight distribution of 2.2 to 2.8 Mw / Mn.

Most preferably, the starting polypropylene resin for the meltblown web of the present invention is a polypropylene reactor granule having a molecular weight distribution of 4.0 to 4.5 Mw / Mn and a melt flow rate of about 2000 g㎳ / 10 min at 230 ° C. The resin is treated with about 500 ppm of peroxide to produce a modified resin having a melt flow rate greater than 3000 g㎳ / 10 min and a molecular weight distribution of 2.8 to 3.5 Mw / Mn at 230 ° C. The wider molecular weight distribution at high melt flow rates minimizes the production of lint cloth and polymer droplets.

Other objects and advantages of the present invention will become apparent with reference to the following detailed description and drawings.

The invention will be illustrated by the preferred embodiments, but the invention is not limited to this embodiment. On the other hand, the invention includes all modifications, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the claims.

1 schematically shows the former 10 used in the manufacture of an SMS fabric laminate 12 having a meltblown barrier layer 32 according to the present invention. In particular, the former 10 consists of a continuous forming belt 14 surrounding the rollers 16 and 18 and the belt 14 is driven in the direction indicated by the arrow. The former 10 has three stations, namely a spun bonding station 20, a meltblowing station 22, and a spun bonding station 24. More than three forming stations may be used to build a higher basis weight layer. Alternatively, each laminate layer is individually formed and rotated, followed by conversion to a non-direct SMS fabric laminate. In addition, the fabric laminate 12 may be formed of three or more or fewer layers, depending on the needs of the particular end use of the fabric laminate 12.

Spun gluing stations 20 and 24 are conventional extruders with spinnerets that form continuous filaments and attach these filaments onto a forming belt 14 in a random interlaced fashion. Spun gluing stations 20 and 24 may include one or more spinnerets, depending on process speed and the particular polymer used. The spun adhesive materials formed are conventional in the art, and the form of such spun adhesive forming stations is known to those of ordinary skill in the art. Spun-bonded nonwoven webs 28 and 36 are made by conventional methods, as described in the following patents; United States Patent No. 3,692,618 to Dorschner et al .; US Pat. Nos. 3,338,922 and 3,341,394 to Kinney; Levi's US Patent No. 3,502,538; Hartmann, US Pat. Nos. 3,502,763 and 3,909,009; US Patent No. 3,542,615 to Dobo et al .; Canadian Patent No. 803,714 to Harmon; And US Pat. No. 4,340,563 to Appel et al. Other methods of forming nonwoven webs with continuous filaments of polymers may also be used in the present invention.

Spun adhesive materials made from continuous filaments have at least three things in common. First, the polymer is extruded continuously through spinnerets to form separated filaments. Secondly, the filaments are mechanically or pneumatically tensioned without breakage to molecularly align the polymer filaments and achieve tack. Finally, continuous filaments are attached to the transport belt in an almost arbitrary manner to form a web. In particular, the spun adhesion station 20 produces a spun adhesive filament 26 from a fiber forming polymer. The filaments are optionally placed on belt 14 to form spunbonded outer layer 28. Fiber forming polymers are described in more detail below.

The meltblowing station 22 consists of a die 31 used to form the microfibers 30. Emission of die 31 is described as molten polymer pounds per inch (PIH) of die width per hour. When the thermoplastic polymer exits the die 31, the high pressure fluid (typically air) weakens and diffuses the polymer stream to form the microfibers 30. Microfiber 30 is optionally attached on top 28 of the spun adhesive layer and forms meltblown layer 32. The structure and method of operating the meltblowing station 22 forming the microfiber 30 and the meltblown layer 32 are conventional, and the form and method of operation thereof are known to those skilled in the art. . Such techniques are described by VA Went, EL Boon, and CD Fluharty (NRL Report 4364, Manufacture of Super-Fine Organic Fibers); NDl Report 5265, An Improved Device for the Formation of Super-Fine Thermoplastic Fibers, by KD Lawrence, RT Lukas, and JA Young; Described in US Pat. No. 3,849,241, filed November 19, 1974 to Buntin et al. Other methods of forming nonwoven webs of microfibers may also be used in the present invention. Meltblowing station 22 produces microfibers 30 from the fiber forming polymers described below. The fibers 30 are optionally attached on top of the spun adhesive layer 28 to form the meltblown inner layer 32. For SMS fabric laminates, for example, the meltblown barrier layer 32 preferably has a basis weight of about 0.01187-0.01695 kg / m 2 (0.35-0.50 oz./yd. ² ).

After the inner layer 32 is attached onto the layer 28 by the meltblowing station 22, the spun bonding station 24 is attached in any orientation on top of the meltblown layer 32 to form a spunbonded outer layer 36. To create a spun adhesive filament 34 that produces). In the case of an SMS medical fabric laminate, for example, each of layers 28 and 36 is preferably from about 0.01017 kg / m 2 (0.30 oz./yd. ² ) to about 0.04069 kg / m 2 (1.2 oz./yd. ² ) has a basis weight of.

The resulting SMS fabric laminate web 12 (FIG. 2) is then fed through adhesive rolls 38 and 40. The adhesive rolls 38 and 40 are provided with protrusion patterns such as spots or grids. The adhesive roll is heated to the softening temperature of the polymer used to form a layer of web 12. As the web 12 passes between the heated adhesive rolls 38 and 40, the material is compressed and heated in an adhesive roll according to the pattern on the roll to separate it as shown in (41) shown in FIG. An area pattern is created, and these areas are bonded between layers and bonded to specific filaments and / or fibers in each layer. Such area separation or spar adhesion is known in the art and is performed as described by heated rolls or by ultrasonic heating of the web 12 to form areas where the filaments, fibers, and layers are thermally adhesive separated. can do. According to the conventional method described in U.S. Patent No. 4,041,203 to Brock et al., In order to obtain excellent strength properties, melting the fibers of the meltblown layer in the fabric laminate in the bonding area while maintaining the filament of the spun adhesive layer as it is. desirable.

According to the present invention, the discharge head (PIH) of the die head 22 has a molecular weight distribution of 4.0-4.5 Mw / Mn and a flow rate of about 400 g㎳ / 10 min at 230 ° C., rather than a pellet type. By providing at the same time. This molecular weight reactor granular polymer is then modified such that the molecular weight distribution of the polymer is limited to 2.2 to 3.5 Mw / Mn by adding up to 3000 ppm peroxide. During the meltblowing process, the modified reactor granular polymer has a melt flow rate increased from 400 g㎳ / 10 min at 230 ° C. to 800 to 5000 g㎳ / 10 min. By modifying the starting polymers, the resulting polymers have lower limiting viscosities, resulting in less force to thin the fibers as they exit the die 31. Therefore, higher melt flow polymers produce finer fibers with commercially available emissions at the same air flow. Commercially available emissions are at least 3 PIH. However, less emissions further reduce the pore size of the fibers and meltblown layer 32.

The resulting meltblown web 32 with fine fibers and small pore size distribution has better barrier properties when incorporated into the fabric laminate. In particular, the unlaminated meltblown web 32 has an average fiber size of 1 to 3 microns, a pore size mainly distributed in the range of 7 to 12 microns, and a small amount of voids of 12 to 25 microns and greater than 25 microns. There are virtually no pores, and the peak of the pore size distribution is less than 10 microns.

When the meltblown web 32 is incorporated into the SMS fabric laminate 12, the peak of the pore size distribution of the resulting SMS fabric laminate shifts down to 5 microns or less. The SMS fabric laminate 12 has a pore size mainly distributed in the range of 5 to 10 microns, a small amount of pores 10 to 15 microns, substantially no pores exceeding 22 microns, and the peak of the pore size distribution is lowered to 5 microns or less. Is moved.

3 shows meltblown webs prepared in accordance with the present invention (Sample 1), SMS fabric laminates prepared using the meltblown webs of the present invention (Sample 2), conventional meltblown (Sample 3), and conventional Evolution of Kimberly-Clark Manufactured Using Meltblown Web ) Pore size distribution of SMS fabric laminate (Sample 4), such as SMS medical fabric laminate. In particular, the meltblown web of the present invention and the SMS fabric laminate of the present invention were prepared by Example 1 below.

The present invention can be carried out with polypropylene, polyolefins including polyethylene, or other alpha olefins polymerized with Ziegler-Natta catalyst technology, and copolymers, terpolymers, or combinations thereof. Polypropylene is preferred.

Two methods can be used to obtain high melt flow polymers useful for making nonwoven webs of fine fibers at commercial production rates. The first preferred method starts from reactor granular polypropylene resin having a molecular weight distribution of 4.0 to 4.5 Mw / Mn and a high melt flow rate of 1000 to 3000 g㎳ / 10 min at 230 ° C. A small amount of peroxide is added to the starting resin to modify the molecular weight distribution in the range of 2.8 to 3.5 Mw / Mn and to increase the melt flow rate to 230 g 5000 g / 10 min at 230 ° C.

The second method for producing nonwoven webs of fine fibers according to the invention starts from reactor granular resins having a molecular weight distribution of 4.0 to 4.5 Mw / Mn and having a lower melt flow rate. Adding more peroxide to the starting resin increases the melt flow rate and broadens the molecular weight distribution. The starting reactor granular polypropylene resin has a molecular weight distribution in the range of 4.0 to 4.5 Mw / Mn and a melt flow rate in the range of 300 to 1000 gPa / 10min at 230 ° C. The polypropylene resin is modified by adding 500-3000 ppm amounts of peroxide (lower initial melt flow rate and higher amounts of peroxide used). The modified polypropylene resin has a melt flow rate of about 3000 g 3000/10 min at 230 ° C. and has a narrower molecular weight distribution of 2.2 to 2.8 Mw / Mn. This second method has a narrower molecular weight distribution of 2.2 to 2.8 Mw / Mn than the first preferred method to form more lint and polymer droplets.

Example 1

To illustrate the invention, the modified blowers of the present invention were used to form meltblowing webs on conventional celbloblowing lines. SMS fabric laminates were also formed using the meltblown web of the present invention as an internal barrier layer. SMS fabric laminates have a spun adhesive layer formed in a conventional manner by polypropylene. The SMS fabric laminate is preferably formed at one time with the multi-station former shown in FIG. Meltblown webs and meltblown barrier layers in SMS fabric laminates were formed from reactor granules of polypropylene having a starting molecular weight distribution of 4.0 to 4.5 Mw / Mn and a melt flow rate of about 2000 g㎳ / 10 min at 230 ° C. The starting polypropylene resin was prepared with a resin of about 500 ppm peroxide with a melt flow rate of greater than 3000 g / 10 min at 230 ° C. and a molecular weight distribution of 2.8 to 3.5 Mw / Mn. The wider molecular weight distribution at high melt flow rates minimizes the formation of lint cloth and polymer droplets.

The meltblown web prepared according to the above had a basis weight of 0.016953 kg / m 2 (0.50 oz./yd. ² ) and is represented as sample 1. The SMS fabric laminate with meltblown inner barrier layer prepared according to the present invention has a spun adhesive layer with a basis weight of 0.01865 kg / m 2 (0.55 oz./yd. ² ) and the meltblown barrier layer has a basis weight of 0.016952 kg. / M 2 (0.50 oz./yd. ² ). The SMS fabric laminate of the present invention is shown in Sample 2. In addition, conventional meltblown webs having the same basis weight as the web and SMS fabric laminates of the present invention and conventional SMS fabric laminates (Evolution fabric laminate from Kimberly-Clark ) Was prepared for control. A control meltblown web is shown as Sample 3 and a control SMS fabric laminate is shown as Sample 4. Samples 1 to 4 have the properties shown in Tables 1 and 2 below.

The pore size distributions shown in Table 1 were measured with coulter porometers. The pore size distribution shown in Table 1 is shown graphically in FIG. The float shown in FIG. 3 shows that Samples 1 and 2 each have a finer pore size distribution compared to Samples 3 and 4. The pore size distribution of the web and SMS fabric laminates of the present invention is narrower than conventional meltblown webs and conventional SMS fabric laminates. The pore size distribution of the SMS fabric laminate of the present invention has a curved peak shifted down to 5 microns from the peak of the meltblown web before lamination. Clearly, the lamination process and additional spun adhesion layers increase the barrier properties of the resulting fabric laminate by bringing the pore structure into close contact.

The distribution of the predominant pore size of 5 to 10 microns indicates that finer fabric laminates (Sample 2) have improved barrier properties in their structure than conventional fabric laminates (Sample 4).

The improved barrier properties of the inventive fabric laminate (Sample 2) compared to conventional fabric laminates (Sample 4) are shown in Table 2 below.

Blood passage was measured by the following method. One piece of each specimen of 7 in. X 9 in. (17.78 cm x 22.86 cm) was placed on top of one sheet of blotter paper of similar size. The blotter was supported on a pouch filled with water and alternately supported on a jack. Jack has an instrument to measure the force received, and calculates the pressure in the pouch on the blotter paper. 1.4 gm of bovine blood sample was placed on top of the fabric sample and covered with one plastic film. The stationary plate was placed on a plastic film. The water bag was then lifted up until the pressure at the bottom of the blotter was maintained at 1 psi. As soon as the desired pressure was reached, the pressure was held for the desired time. After that time, the pressure was released, the blotter paper was removed, and weighed. Percentage of passage was determined based on the before and after difference in blotter weight.

The test results show that the SMS fabric laminates produced by the present invention have particularly good passage properties over a short time. Short course of time refers to a situation that is commonly encountered in medical applications where blood typically does not remain on the drape or gown for a long time before it can be wiped off.

Filterability was measured to determine the ability of SMS fabric laminates to prevent invasion of aerobic bacteria. The samples were Mil. Spec. 36954-C Tested according to 4.4.1.1.1 and 4.4.1.2. A 3.5% increase in efficiency within the + 90% range indicates a significant improvement in the ability to filter and inhibit the passage of aerobic bacteria.

Claims (45)

A nonwoven web of fine fibers formed from reactor granules of modified polymer having a molecular weight distribution of 2.2-3.5 Mw / Mn and a melt flow rate of greater than 800 g㎳ / 10 min at 230 ° C. The nonwoven web of claim 1 wherein the web is formed when the polymer emissions exceed 3PIH. The nonwoven web of claim 1 wherein the web has an average fiber size of 1 to 3 microns, a pore size is distributed primarily in the range of 7 to 12 microns, and a peak of the pore size distribution is less than 10 microns. A nonwoven web formed from reactor granules of modified polymer having a molecular weight distribution of 2.8 to 3.5 Mw / Mn and a melt flow rate of greater than 3000 g㎳ / 10 min at 230 ° C. The nonwoven web of claim 4 wherein the modified polymer is produced by adding up to 500 ppm of peroxide to the reactor granules before forming the web. 6. The nonwoven web of claim 4 or 5 wherein the web is formed when the polymer emissions exceed 3PIH. 6. The nonwoven web of claim 4 or 5 wherein the web has an average fiber size of 1 to 3 microns and a pore size is distributed primarily in the range of 7 to 12 microns and less than 10 microns of the peak of the pore size distribution. A nonwoven web formed from reactor granules of modified polymer having a molecular weight distribution of 2.2 to 2.8 Mw / Mn and a melt flow rate of greater than 800 g㎳ / 10 min at 230 ° C. 9. The nonwoven web of claim 8 wherein the modified polymer is produced by adding 500-3000 ppm peroxide to the reactor granules before forming the web. 10. The nonwoven web of claim 8 or 9, wherein the web is formed when the polymer emissions exceed 3PIH. 10. The nonwoven web of claim 8 or 9, wherein the web has an average fiber size of 1 to 3 microns, a pore size mainly in the range of 7 to 12 microns, and a peak of the pore size distribution is less than 10 microns. Nonwoven with small pore size distribution with fine fibers, consisting of meltblowing the reactor granules of the modified polymer having a molecular weight distribution of 2.2 to 3.5 Mw / Mn and a melt flow rate of greater than 800 gmin / 10 min at 230 ° C. How to form a web. The method of claim 12, wherein the polymer has an emission greater than 3PIH. Nonwoven with fine pore and small pore size distribution, consisting of meltblowing reactor granules of modified polymer having a molecular weight distribution of 2.8 to 3.5 Mw / Mn and a melt flow rate of greater than 3000 g㎳ / 10 min at 230 ° C. How to form a web. 15. The process of claim 14, wherein the modified polymer is produced by adding up to 500 ppm of peroxide to the reactor granules before forming the nonwoven web. 16. The method of claim 14 or 15, wherein the polymer has an emission greater than 3PIH. Nonwoven web with fine porosity and small pore size distribution, consisting of meltblowing reactor granules of modified polymer having a molecular weight distribution of 2.2 to 2.8 Mw / Mn and a melt flow rate of greater than 800 g㎳ / 10 min at 230 ° C. Method of formation. 18. The process of claim 17, wherein the modified polymer is produced by adding 500-3000 ppm peroxide prior to forming the nonwoven web. 19. The method of claim 17 or 18, wherein the amount of polymer released is greater than 3PIH. A nonwoven laminate having a barrier layer formed from reactor granules of modified polymer having a molecular weight distribution of 2.2 to 3.5 Mw / Mn and a melt flow rate at 230 ° C. of greater than 800 gm / 10 min. The nonwoven laminate of claim 20 wherein the polymer is a polyolefin. The nonwoven laminate of claim 21 wherein the polymer is polypropylene. The nonwoven laminate of claim 20 wherein the pore size of the woven laminate is distributed primarily in the range of 5 to 10 microns and the peak of the pore size distribution is less than 10 microns. 24. The nonwoven laminate of claim 23, wherein the pore size of the nonwoven laminate is predominantly distributed in the range of 5 to 10 microns, a small amount of pore is distributed in the range of 10 to 15 microns, and there are substantially no pores having a pore size of at least 22 microns, 10 micron nonwoven laminate with a peak of pore size distribution. A nonwoven laminate having a barrier layer formed from a polymer having a molecular weight distribution of 2.8 to 3.5 Mw / Mn and a melt flow rate at 230 ° C. of greater than 3000 gm / 10 min. The nonwoven laminate of claim 25 wherein the polymer is a polyolefin. 27. The nonwoven laminate of claim 26 wherein the polymer is polypropylene. 27. The nonwoven laminate of claim 25 wherein the pore size of the fabric laminate is predominantly distributed in the range of 5 to 10 microns and the peak of the pore size distribution is less than 10 microns. 29. The nonwoven laminate of claim 28, wherein the pore size of the nonwoven laminate is predominantly distributed in the range of 5 to 10 microns, a small amount of pore is distributed in the range of 10 to 15 microns, and there are substantially no pores having a pore size of at least 22 microns, Nonwoven laminate with a peak in pore size distribution of less than 10 microns. The nonwoven laminate of claim 20 wherein the molecular weight distribution of the modified polymer is from 2.2 to 2.8 Mw / Mn. 31. The nonwoven laminate of claim 30 wherein the polymer is a polyolefin. 32. The nonwoven laminate of claim 31 wherein the polymer is polypropylene. A nonwoven SMS fabric laminate having a barrier layer formed from a polymer having a molecular weight distribution of 2.2 to 3.5 Mw / Mn and a melt flow rate at 230 ° C. of 800 gm / 10 min. 34. The nonwoven SMS fabric laminate of claim 33, wherein the polymer is a polyolefin. 35. The nonwoven SMS fabric laminate of claim 34, wherein the polymer is polypropylene. The nonwoven SMS fabric laminate of claim 33 wherein the modified polymer has a molecular weight distribution of 2.8 to 3.5 Mw / Mn and a melt flow rate at 230 ° C. of greater than 3000 gm / 10 min. 37. The nonwoven SMS fabric laminate of claim 36, wherein the polymer is a polyolefin. 38. The nonwoven SMS fabric laminate of claim 37, wherein the polymer is polypropylene. The nonwoven SMS fabric laminate of claim 33 wherein the molecular weight distribution of the modified polymer is from 2.2 to 2.8 Mw / Mn. Sterile wrap comprising the laminate of claim 20. A welfare fabric comprising the laminate of claim 20. A sterile wrap comprising the laminate of claim 33. A welfare fabric comprising the laminate of claim 33. Surgical fabric comprising the laminate of claim 20. A surgical fabric comprising the laminate of claim 33.