MXPA06007290A - Meltblown die having a reduced size - Google Patents

Abstract

The present invention provides a meltblown die which has a considerable smaller width in the machine direction of the meltblowing process compared to conventional and commercially used meltblown dies. The meltblown dieof the present invention has a. a die body;b. a die tip mounted to the die body;c. a first air plate mounted to the die body;and d. a second air plate mounted to the die body. In addition, the small size of the meltblown die of the present invention provides advantages over conventional meltblown die, including improved air entrainment.

Description

Published: - with international search report For two-letter codes and other refer to the "Guid-ance Notes on Codes and Abbreviations" appearing at the beginning-ning ofeach regular issue of the PCT Gazetle.

BLOWED MATRIX WITH FUSION THAT HAS SIZE OR REDUCED Field of the Invention The present invention relates to a meltblown matrix assembly and fiber formation using the meltblown matrix assembly in a meltblown process.

Background of the Invention The formation of fibers and non-woven fabrics by meltblowing is well known in the art. See, by way of example, US Pat. Nos. 3,016,599 issued to R. W. Perry, Jr .; 3,704,198 awarded to J. S. Prentice; 3,755,527 issued to J. P. Keller et al .; 3,849,241 granted to 3,849,241 granted to R. R. Butin and others; 3,978,185 granted to R. R. Butin and others; 4,100,324 issued to R. A. Anderson and others; 4,118,531 granted to E. R. Hauser; and 4,663,220 granted to T. J. Wisneski and others.

Briefly, meltblowing is a process developed for the formation of fibers and non-woven fabrics; the fibers are formed by extruding a molten thermoplastic polymeric material, or polymer, through a plurality of small holes. The resulting fused filaments or filaments pass into converging high velocity gas streams, which are often heated, which attenuate or pull the filaments of molten polymer to reduce their diameters. Then, the meltblown fibers are transported by the high velocity gas stream and deposited on a collection surface, or forming wire, to form a non-woven fabric of randomly dispersed meltblown fibers.

Generally, meltblowing uses a specialized apparatus to form blown fabrics with melting of a polymer. Often, the polymer flows from a matrix through narrow cylindrical outlets and forms the meltblown fibers. The narrow cylindrical outlets may be arranged in a substantially straight line and lie in a plane which is the bisector of a V-shaped matrix tip. Typically the angle formed by the walls or the outer faces of the shaped die tips of V is 60 ° and is placed next to a pair of air plates and, therefore, they form two grooved channels along each face of the die tip. Therefore, air can flow through these channels to bump into the fibers coming out of the die tip, thereby attenuating the fibers. As a result of several dynamic actions of the fluid, the air flow is capable of attenuating the fibers to diameters of from about 0.1 to 10 micrometers; such fibers they are generally referred to as "microfibers". Larger diameter fibers, of course, are possible, with the diameter in the range of from about 10 micrometers to about 100 micrometers. Generally, fibers having a top fiber diameter of about 40 microns are referred to as "macro fibers." The conventional meltblown die array has not changed since 1960. The most widely used configuration is the type of design which is described in U.S. Patent No. 3,825,380. A majority of commercially available MB systems are composed of a matrix body, a die tip and air plates. Over the years, there have been improvements to the mechanical and air distribution systems of the meltblown dies, but little has been achieved to change the physics of blown dies with standard melting.

One of the problems with current meltblowing dies is the large amount of space required by the meltblown die. Current fusion blow designs may require 1.0 to 1.5 meters (3 to 5 feet), often 1.25 to 1.5 meters (4 to 5 feet) in length in the machine direction per melt blow bench, which includes the air handling equipment. Because it is often advantageous to have more than one melting bank with melting in A production line, a relatively large amount of one-story space is needed to accommodate a production line that has no or more melt blown die assemblies.

Synthesis of the Invention The present invention provides a meltblown matrix which has a considerably smaller width in the machine direction of the meltblowing process compared to conventional and commercially used meltblown dies. The meltblown matrix of the present invention has to. a body of matrix; b. a die tip mounted to the die body; c. a first air plate mounted to the die body; and d. a second air plate mounted to the matrix body. The total width of the meltblown matrix in the machine direction is less than about 16 centimeters (6.25 inches). In the present invention, desirably the total width in the machine direction of the melt blown array assembly is generally in the range of 5 to 10 centimeters (2 to 4 inches).

In another embodiment of the present invention, a meltblown matrix is described as having to. a body of matrix; b. a die tip having an upper side, a lower side, a first side and a second side, wherein the top sides are mounted to the die body, the bottom side is opposite the top side, the first side and the second side each extend from the upper side to the lower side, and the first side and the second side are opposite each other. c. a first air plate, wherein a part of the first air plate is in contact with the first side of the tip of the die and a series of channels are formed by the first side of the die tip and the first air plate; and d. a second air plate, where a part of the second air plate is in contact with the second side of the tip of the matrix and a series of channels are formed by the second side of the matrix tip and the second air plate . In this embodiment of the present invention the channels are and may be desirably formed on the first side and on the second side of the tip of the die such that each of the first and second side of the die tip have a surface comprising a series of raised portions extending from the upper side of the tip of the die to the underside of the tip of the die. These elevated parts that define a series of channels between the parts raised on each side of the tip of the die extending from the upper side of the tip of the die so the lower degree of the tip of the die. The first air plate contacts at least a portion of the raised portions of the first side of the die tip and the second air plate contacts at least a portion of the raised portions of the second side of the die tip. The channels on the sides of the tip of the matrix and the air plates provide trajectories which allow the attenuation of the fluid to pass from the body of the matrix to an exit of the meltblown matrix.

In another embodiment of the present invention, a meltblown matrix is described as having to. a body of matrix; b. a die tip mounted to the die body; c. a first air plate mounted to the die body; d. a second air plate mounted to the die body; and e. a distribution chamber which provides a path for a material to be formed in a fiber of the body from the die to the tip of the die where the distribution chamber has a non-linear shape in the cross machine direction. By having a distribution chamber with a non-linear shape, the mounting means which mounts at the tip of the die to the play of the die body in a stepped manner, typically from side to side at the tip of the die. matrix, while providing a sufficiently firm mechanism to keep the tip of the matrix in place during use.

In each of the embodiments of the present invention, the die body may additionally have a mounting plate mounted to the body of the die. If present, the air plates and the tip of the die are mounted to the mounting plate.

Brief Description of the Drawings Figure 1 shows a schematic of a standard melt blowing process.

Figure 2 shows a cross-sectional view of a meltblown matrix of the present invention.

Figure 3 shows a partial top view of a portion of a tip of the meltblown die of Figure 2.

Figure 4 shows a cross-sectional view of a meltblown matrix of the present invention.

Figure 5 shows a partial inside view of the assembly plate of the meltblown die of Figure 4.

Figure 6 shows a partial top view of the mounting plate with a non-linear polymer distribution chamber.

Figure 7 shows a partial top view of the tip of the meltblown die of Figure 4.

Figure 8 shows a cross-sectional view of a melt blown die of a meltblown die of the present invention with a mounting plate used to maintain the tip of the die of the figure 4 in the body of the matrix.

Definitions As used herein, the term "comprising" is inclusive or open-ended and does not exclude elements, components of the composition, or additional non-recited method steps.

As used herein, the term "consisting essentially of" does not exclude the presence of additional materials which do not significantly affect the desired characteristics of a given composition or product. Exemplary materials of this type may include, without limitation, pigments, antioxidants, stabilizers, surfactants, waxes, flow promoters, particles, and aggregate materials to improve the process of the composition.

As used herein, the term "polymer" generally includes, but is not limited to, homopolymers, copolymers, such as, for example, block, graft, random and alternating copolymers, terpolymers, etc. and the mixtures and modifications thereof. In addition, unless otherwise specifically limited, the term "polymer" should include all possible geometric configurations of the module. These configurations include, but are not limited to, isotactic, syndiotactic and random symmetries.

As used herein, the term "non-woven fabric" means a fabric having a structure of individual fibers or threads which are interlocked, but not in an identifiable manner as a knitted fabric. Non-woven fabrics have been formed from many processes, such as, for example, meltblowing processes, yarn-linking processes, air laying processes, cofor processes and the processes of bonded carded fabric. The basis weight of the non-woven fabrics is usually expressed in ounces of material per square yard (osy) or in grams per square meter (gsm) and the diameters of the useful fibers are usually expressed in microns, or in the case of fibers basic, the denier. It is noted that to convert from ounces per square yard to grams per square meter, ounces per square yard are multiplied by 33.91.

"Blown with melting" refers to the fibers formed by extruding a molten thermoplastic material through a plurality of capillary, usually circular, thin vessels such as wires or filaments into streams (eg, air) of high velocity hot gas that converge which attenuate the filaments of molten thermoplastic material to reduce their diameters. After, the meltblown fibers are transported by the high velocity gas stream and are deposited on a collection surface to form a randomly dispersed meltblown fiber fabric. Meltblown processes can be used to make fibers of various dimensions, including macro fibers (with average diameters from about 40 to about 100 microns), textile type fibers (with average diameters between about 10 and around of 40 microns), and microfibers (with average diameters less than about 10 microns). The processes of melt blown are particularly suitable for making microfibers, which include ultra-fine microfibers (with average diameters of about 3 microns or less). The meltblown fibers may be continuous or discontinuous, and are generally self-adhesive when deposited on a collection surface. The meltblowing process is well known and is described by several patents and publications described above.

The term "machine direction" as used herein refers to the path direction of the forming surface in which the fibers are deposited during the formation of a material.

The term "transverse machine direction" as used herein refers to the direction in the same plane of the tissue that is formed which is perpendicular to the machine direction.

Detailed description of the invention In order to have a better understanding of the present invention, attention is directed to Figure 1, which generally shows a conventional fusion blowing process of the prior art. Generally described, in a meltblowing process, a hopper 10 provides polymer to the extruder 12 which is driven by a motor 11 heated to bring the polymer to the desired temperature and viscosity. The molten polymer is supplied to the matrix 14 which can also be heated by means of a heater 16. The matrix is connected via conduits 13 to a supply of attenuating fluid. At the outlet 19 of the die 14, the fibers 18 are formed and collected in a forming band 20 with the aid of an optional suction box 15 which forms a fabric 22 which can be compacted or otherwise joined by rollers 24 and 26. The band 20 can be rotated by means of an imposing roller which can be either 21 or 23, for example. In Figure 1, the direction of the arrow 28 shows the direction in which the fabric is formed, which is referred to as the machine direction and the date 30 shows a direction perpendicular to the machine direction, which is referred to as the cross machine direction.

Returning to Figure 2, this figure shows an incorporation of a meltblown matrix 100 of the present invention in a partial cross-sectional view. In Figure 2 a die tip 102 is mounted directly to the die body 103 (partially shown) through a mounting plate 104. Also mounted to the die body mounting plate 104 or there is a first air plate 106a and a second air plate 106b. The tip of the die 102 is mounted to the mounting plate 104 using any suitable means such as Bolts The bolts 110a and 110b are shown as the mounting means in Figure 2. In a similar manner, the air plates 106a and 106b are also shown to the mounting plate 104 using an appropriate mounting means, such as bolts. The bolts 112a and 112b are shown as the mounting means for the air plates in Figure 2. It is noted that a mounting plate 104 is not necessary and the tip of the die 102 and the air plates 106a and 106b can be It is desirable to mount the tip of the die 102 and the air plates 106a and 106b to the mounting plate 104, since it is easier to couple the tip of the die to the mounting plate 104 which the body of the die 103 using a mounting means (not shown).

The tip of the die 102 has an upper side 160, and two side sides 162a and 162b, which extend from the upper side to the lower side 161 of the tip of the die. Additionally, the tip of the die may have a tip apex of the die 128 and a breaker / shield plate assembly 130. The material which may be formed into fibers is supplied from the die body 103 to the tip of the die 102 by means of a path 132. The material passes through a distribution plate 131 of the path 132 to the circuit breaker / screen plate assembly 130. Once through the circuit breaker / filter plate assembly 130, the which serves to filter the material to prevent any impurities which can plug the tip of the die to pass further through the tip of the die 102, the material passes through a narrow path 133 to a cylindrical outlet narrow or another 129, which expels the material, so it forms the fibers. Typically, the outlet 129 may generally have a diameter in the range of about 0.1 to about 0.6 millimeters. The outlet 129 is connected to the narrow path 133 by means of capillary vessels 135, which have a diameter around the same outlet and the capillary vessels may have a length which is generally about 3 to 15 times the diameter of the vessels. capillaries of the tip of the matrix. The actual diameter and length of the outlet and capillary vessels may vary without departing from the scope of this invention.

A high velocity fluid, generally air, must be supplied at the outlet of the tip of the die 129 in order to attenuate the fibers. In the meltblown matrix of the present invention, the attenuating fluid is supplied through an inlet (not shown in Figure 2 but described in greater detail in Figure 8 below) in the body of the die 103, so it saves space in the machine direction. In many commercially used and conventional meltblown matrices, the attenuating fluid is supplied external to the die body, therefore requiring large amounts of space in the direction of machine. The attenuating fluid passes through the body of the die 103 through paths 140a and 140b in the mounting plate 104 into distribution chambers 141a and 141b, respectively. The distribution chambers allow the mixing of the attenuating fluid. From the distribution chambers 141a and 141b, the attenuating fluid is then passed between the air plates 106a and 106b, and the tip of the matrix 102 by means of the paths 120a and 120b. the air plates 106a and 106b are secured to the mounting plate 104 (alternatively to the body of the die 103) in such a manner that the air plates 106a and 106b and the tip of the die 102 of the paths 120a and 120b, which they allow the attenuating fluid to pass from the distribution chambers and 141a and 141b in the mounting data 104 to the exit opening 129 at the tip of the die. Additionally, the air plates 106a and 106b are close to the bottom of the tip of the die 161 in the channels 114a and 114b which allow the attenuating fluid to pass from the paths 120a and 120b to the outlet opening 149 of the matrix blow molding 100. The dampers 115a and 115b assist in the mixing of the attenuating air in the channels 114a and 114b so that scratching of the attenuating fluid does not occur.

The meltblown dies of the present invention have a reduced width in the machine direction.

Typically, the meltblown dies of the present invention have a width in the machine direction of less about 16 centimeters (6.25 inches). Most of the meltblowing matrices of the present invention have a width in the machine direction in the range of about 2.5 centimeters (1 inch) to about 15 centimeters (5.9 inches) and desirably about 5 centimeters (2 inches). inches) up to about 12 centimeters (4.7 inches). This reduced size is a direct result of any of the unique characteristics of meltblowing matrices which are described in more detail below.

A first feature of the meltblowing matrices of the present invention is that the attenuating fluid is introduced to the meltblown die assembly in the die body 103. In order to obtain attenuating air from the body of the 103 to outlet 149 of melt blown 100, the present invention provides paths or channels 120a and 120b created by the tip of die 102 and air plates 106a and 106b, respectively. Any means can be used to form pathways 120a and 120b. One method for providing these channels is to form the tip of the die such that the sides of the tip of the die 162a and 162b have grooves or channels (shown in FIG. 3) that extend from the upper side 160 to the side. lower 161 of the tip of the matrix. The grooves are formed by forming a series of raised portions on the sides 162a and 162b which are separated by a series of depressed areas or channels. In other words, the raised portions on the sides 162a and 162b of the tip of the die define the channels and these channels extend from the upper side 161 of the tip of the die to the lower side 161 of the tip of the die.

To obtain a better understanding of the structure and the channels formed on the sides of the tip of the matrix, attention is directed to Figure 3, which shows a top view of the tip of the matrix 102, looking down on the surface 160 along the section of line AA in Figure 2. A series of raised portions 201 on the sides 162a and 162b of the tip of the die 102 defines a series of whitewashed channels 202 (162a and 162b) of the tip of the matrix. The air plates 106a and 106b are set against the raised portions 201, such that the paths of the paths 120a and 120b (FIG. 2) are formed by the channels 202 in the air plates. This allows for the attenuating fluid to pass from the body of the die 103 or the mounting plate to the outlet 149 of the meltblown die 100. The channels created on the sides of the tip of the die may have a width , or the distance between the raised portions (w) and a depth, or the distance of the raised portions extend away from the recessed part that the channel (d). Depending on the total size of the meltblown matrix, the channels 202 formed can be from about 0.25 to about 4.0 millimeters in width (w) and from around 0.25 to about 4.0 deep (d). As an alternative, other methods for providing pathways 120a and 120b between the air plates and the tip of the die can be used, such as, for example, providing air plates with a series of raised portions defining a series of channels and in much the same way that the channels are supplied on the side of the tip of the array. However, from a cost point of view, it is preferred that the tip of the die, which is already produced by milling, be supplied with a series of raised parts.

Additionally, the raised portions 201 on the sides of the die tip also supply a line shape to the air plates 106a and 106b in the array assembly. The air plates can rest directly on the sides of the die tip 102 and are held in place by any appropriate means, generally bolts. This can avoid the need for separators or alignment plates which are generally used in conventional blow molding dies.

The pathways 120a and 120b formed from the series of the raised portions 201 on the sides of the tip of the die 102 and the pair of air plates 106a and 106b, already allow for the distribution of fluid that attenuates before the informed of the air nozzles converging on the outlets 149 of the meltblown matrix. The structure formed by the raised portions 201 and the plates 106a and 106 (b) is very similar to that of a perforated plate. Perforated plates tend to yield better or near-ideal air distribution to other structures used in air distribution.

Another feature of the present invention is that the tip of the material 102 is mounted to the assembly 104 using a mounting mechanism which extends from the mounting plate 104 (or die body 103) of the upper surface 160 of the tip 102. As shown in Figure 2, the tip of the die 102 is mounted on the mounting plate 104 with mounting means extending from the mounting plate 104, through the upper surface 160 of the tip of die and on tip of die 102. Fig. 3 shows mounting holes 210 for mounting tip of die 102 to mounting plate 104 are located on upper surface 160 of die tip 102.

Conventionally, the die tips are mounted with a mounting mechanism on the underside of the die tip, which exposes the mounting mechanism to the attenuating air. The fluid that attenuates which passes through the meltblown matrix is sometimes referred to as "primary fluid", in the case of air as the fluid that attenuates, "primary air". It has been discovered that when the mounting mechanism, usually bolts, are exposed to the Fluid stream that attenuates tend to cause scratches in the fluid it attenuates, thus adversely affecting the formation of the fibers. By mounting the tip of the die 102 to the mounting plate 104 using a mounting mechanism of the upper surface 160 of the tip of the die 102 below the lower surface 161 of the tip of the die, the formation of the improved fiber can performed due to the lack of scratches caused by the mounting means of the die tip 102 in the primary fluid flow. It has been found that the reduced size of the meltblown matrix improves the entrainment of fluid from the primary attenuating fluid.

Also shown in Figure 3 is the polymer distribution plate 131 and the circuit breaker plate / screen 130, as seen from the top of the tip of the die 102.

An alternate meltblown matrix within the present invention is shown in FIG. 4 in an amplified view. In Figure 4, this figure shows an alternate incorporation of a meltblown matrix 400 of the present invention in a partial cross-sectional view. In Figure 4 the tip of the die 412 is mounted on a mounting plate 404. Also mounted to the mounting plate 104 are a first air plate 406a and a second air plate 406b. The tip of the array 412 is mounted to the mounting plate 404 using any suitable mounting means previously described. Also shown in Figure 4 the bolts 410 are used as an appropriate mounting means. In a similar manner, the air plates 406a and 406b are also mounted to the mounting plate 404 using an appropriate means, such as the bolts 412a and 412b. It is noted that the mounting plate is optional, but desirably as mentioned above.

The tip of the array 402 has an upper side 460, and two sides 462a and 462b, which extend from the upper side towards the lower side 461 of the tip of the array 402. As with the meltblown array shown in FIG. Fig. 2, the air plates 406a and 406b of the meltblown die of Fig. 4 are secured to the mounting plate 404 in such a manner that the air plates 406a and 406b and the tip of the array 402 of the trajectories 420a and 420b, which allow the attenuating fluid to pass from the distribution chambers 441a and 441b present in the mounting plate 404 to the outlet opening of the meltblown matrix 449. The attenuating fluid system operates in in the same manner as previously described for Figure 2. The attenuating fluid passes from chambers 439a and 439b in the body of matrix 403 in paths 440a and 440b and in distribution chambers 441a and 441b, respectively. From the distribution chambers 441a and 441b, the attenuating fluid is then passed between the air plates 406a and 406b and the tip of the array 402 by means of the paths 420a and 420b.

Additionally, the digested plates 406a and 406b are close to the bottom of the tip of the die 461 such that the channels 414a and 414b which will allow the attenuating fluid to pass from the paths 420a and 420b to the outlet 449.

In the configuration of the matrix shown in Figure 4, a unique assembly of the tip of the matrix and a polymer distribution system (also called a polymer distribution chamber) are used. The used polymer distribution system has a non-linear course in the cross machine direction. Additionally, the mounting means 410 is alternated from side to side or stepped to allow the non-linear course of the polymer distribution system. To obtain a better understanding of the non-linear polymer distribution system and the alternating mounting medium, attention is directed to figure 5, which shows a partial bottom view, in the cross machine direction, the assembly to along the section cut from line AA in figure 4.

In operation of the meltblown matrix 400, the material which may be formed into fibers is supplied to and from the body of the die 403 to the tip of the die 402 by means of a path 432. The path 432 may narrow to a smaller path 433 which is directly connected to the polymer distribution chamber 470. The polymer distribution chamber 470 has a non-linear course in the cross machine direction, as shown in Figure 5. In Figure 5, the upper part of the polymer distribution chamber 470 finds the path 433 near the center of the mounting plate 404. The material to be formed in the fibers penetrates and flows through the polymer distribution chamber 470. As seen, the polymer distribution chamber 470 has a non-linear course in the cross machine direction. The polymer distribution chamber 470 weaves a path around the mounting means of the tip of the array 410 and the bypass ports 411. Although shown as a serpentine form, other non-linear courses can be used for the distribution chamber of polymer 470, for example a zigzag pattern. Also shown in Figures 5 are the fluid paths 440a and 440b of the bypass ports 413 for the air plate mounting means 412a and 412b. The mounting plate 404 is mounted to the body of the die by means of an appropriate coupling means by means of the bypass ports 417 shown in figures 5.

Once in the polymer distribution chamber 470, the material to be formed in the fibers is then passed on a path 471 to the polymer distribution plate 430 and the circuit breaker / filter plate assembly 431. As with the top of the the polymer attribution chamber 1470, the bottom of the polymer distribution chamber 470 has a non-linear course in the cross machine direction. The upper part of the camera and the bottom of the camera can generally have the same shape. Therefore, the distribution of the material to be formed in fibers of the chamber 470 to the tip of the matrix 412 may also have a unique configuration. This configuration is shown in Figure 6, which is a partial sectional view of the array set observed downstream of the sectional line B-B. As seen in Figure 6, the bottom of the polymer distribution chamber 470 has a shape similar to that of the upper part of the chamber. The outlet 437 of the polymer distribution chamber 470 is positioned around the mounting means of the tip of the die 410 and of the bypass opening of the mounting means of the tip of the die. This allows the material to pass at the tip of the array 402.

Additionally, the upper portion of the tip of the array 402 may have a unique structure. As shown in Figure 7 is a partial view of the tip of the array 402 observed down from the sectional line C-C, with the circuit breaker / filter plate assembly removed. Once through path 438, called the polymer port, material enters the tip of matrix 402 and into the area of the polymer distribution plate. Once in the polymer distribution plate, the polymer preferably passes through a circuit breaker plate / screen (not shown) to filter the material so that the impurities can not cover the exit 429 from the tip of the matrix 402. The material leaves the circuit breaker plate, the material can enter the path to take the material to the final capillaries to form the fibers. As shown in Figure 7, the tip of the die 402 can additionally have a series of raised portions 201 that define a series of channels 202 which are described in more detail above. Also shown in Figure 7 are the bypass ports 411 for the mounting means of the tip of the die 410.

Returning to Figure 4, from the polymer port 438, the material can optionally enter an optional polymer pond chamber of 434. The polymer pond chamber 434 can be the length of the melting blow matrix in the direction Transverse to the machine or the polymer stagnation chamber can be a series of cameras. Ideally, the polymer pond chamber is a series of chambers. The polymer pond chamber is not required, but allows the polymer passing through the polymer ports to be supplied to a common channel before being fed to the final capillary vessels 436. The final capillary vessels may be cylindrical or another shaped outlets and allow the polymer to be expelled the material into the outlet openings of the die tip 429, thereby forming the fibers.

By using a non-linear polymer distribution chamber 470, the overall width of the meltblown matrix can be reduced in the machine direction. Meltblowing matrices having this configuration can be made to have widths in the machine direction of about 5 centimeters (or more generally up to 14 centimeters). Larger melting blow matrices also use this configuration as a space-saving measure.

As can be seen in Figure 4, the die tip 402 can be formed in two pieces, the upper part 437 and the lower part 435. The upper part 437 houses the polymer ports of the breaker plate assembly 431 and is in contact with it. the mounting plate 404. The lower portion 435 of the die tip houses the polymer pond chamber 434 and the final capillary vessels 436 are shown as a separate section 435 of the die tip 402. The die tip is advantageously produced in two parts so that the polymer ports 438 can be easily machined at the die tip. This is essentially true since the polymer ports in Figure 4 are machined at the die tip 402 at an angle to obtain the polymer from the breaker plate / filter assembly 431 at the outlet of the die tip 429. When the two-part die tip 402 is used, the lower section 435 with the polymer stagnation chamber and the top section 437 can be together using known techniques such as the electronic beam soldier. Furthermore, it is noted that a two piece die tip can be prepared in the embodiment of Fig. 2; however, it is not necessary since the polymer ports and the final capillary vessels are perpendicular to the top of the matrix tip 102.

As can also be seen in Figure 4, the mounting plate 404 can be prepared in two or more pieces, such as for example the mounting plate can have an upper part 405 and a lower part 407. As with the die tip, the The non-linear polymer distribution chamber 470 needs to be machined into the mounting plate 402. One way to achieve this task is to form a two-piece mounting plate as shown in figure 4. The two pieces of mounting plate they can be joined together by any known technique, provided that the joining method supports the processing conditions applied to the meltblown matrix.

In order to obtain a complete and comprehensive understanding of the many characteristics of the blow matrices of the present invention, certain characteristics of the die body have not been discussed in detail above. The attention should be directed to Figure 8 which shows a cross-section of a global fusion blowing matrix of the present invention.

In Figure 8, a meltblown matrix 500 is shown in a cross-sectional view. The meltblown matrix 500, has the die body 503, an optional mounting plate 504. A die tip 502 and the air plates 506. The die body 503 is mounted to a support not shown, by an assembly suitable through the lid holes 601. In the die body 503, there is an attenuation fluid inlet 604 and a material inlet 606. The material to be formed in the meltblown fibers is typically a polymeric material.

The material is typically provided from a hopper (not shown) to an extruder (not shown) and is typically heated to bring the material to the desired temperature and viscosity. The melted material is provided to the meltblown matrix through the material inlet 610. The material can also be heated in the meltblown matrix by means of a heater (not shown). Once in the matrix body, the material passes through a 610 to the mounting plate 504. From there, the polymer passes through the mounting plate 504 to the matrix tip 502 and through the final capillary vessels and it forms the fibers when leaving the capillaries. As shown in Fig. 8, the mounting plate 504 and the die tip 502 are identical to the mounting plate and the die tip shown in Fig. 4. Therefore, the flow of the material to Through the mounting plate will not be repeated. For a full discussion please see the discussion of figure 4.

The attenuation fluid enters the meltblown matrix through the opening in the die body 604. The quench fluid may or may not be heated before entering the die body 503. Upon entering the quench fluid in the matrix body, the fluid enters a chamber 611. From this chamber, the attenuation fluid is sent through the conduits 613 on its way to the chambers 439a and 439b. From this point, the attenuation fluid passes through the mounting plate 504 and between the die tip 502 and the air plates 506 in a manner described above. The attention again addresses the discussion of the attenuation fluid associated with Figure 4.

The mounting plate 504 is mounted on the die body 503 through suitable mounting means 620. Any suitable means can be used, but it is generally preferred that the bolts be used to mount the mounting plate on the die body . As stated above, mounting plate 504 is optional. The die tip is mounted on the mounting plate 504 through the mounting means 510 which mount the die tip on the mounting plate through the cap of the die tip 502. Again, it is desirably that a bolt is used to mount the die tip on the mounting plate since the Bolts are easily removed if the disassembly of the melting blow mold is necessary. Finally, the air plates 506 are also mounted on the mounting plate using the mounting means, preferably a bolt.

As described above, the present invention is described in terms of having a mounting plate between the die tip and the die body. As stated above, the mounting plate is optional, but it is desired, since it is easier to mount the die tip and the air plate to the assembly in general and it is often easier to form the necessary conduits and channels in a Matrix plate against the matrix body itself.

As stated above, the present invention is directed to reducing the width in the machine direction of the meltblown die. Other ways of making a smaller melting blow matrix include, for example, reducing the size of the mounting apparatus, using a mounting apparatus with a smaller width in the machine direction, such as T bolts and reducing the size of filter in the breaker plate.

An additional feature which can be incorporated are means for activating and deactivating the polymer supply inside the die tip. The reduced size means that less polymer is present in the blowing matrix with fusion at any given moment. In conventional melt blowing matrices, it is difficult to activate or deactivate the polymer supply in a designated manner due to the high polymer content at a given time. However, with the reduced polymer content in the meltblown matrix of the present invention at a given time the polymer supply can be more easily stopped and can also be started without the problems encountered in conventional meltblowing matrices. due to the reduced volume of the polymer at the die tip.

The die tip itself can be manufactured from materials conventionally used to make the die tips such as stainless steel, aluminum, carbon steel or bronze. In the alternate incorporations, the matrix is made of insulating materials. The die tip may be constructed in one piece or may be a multi-piece construction, and the die openings may be perforated or otherwise formed. Given the size of the die tips of the present invention and the angles of some of the polymer ports, it is generally preferred but it is not required that the die tip be prepared in two pieces and the two pieces welded together. When a two part die tip is produced, the parts are welded together with electronic beam. Similarly, the mounting plate can also be prepared in more than one piece.

The fibers produced using the meltblown matrix of the present invention can be prepared from any polymer, in particular, any thermoplastic polymer. Polymers suitable for the present invention include the known polymers suitable for the production of non-woven fabrics and materials such as for example polyolefins, polyesters, polyaids, polycarbonates and copolymers and mixtures thereof. Suitable polyolefins include polyethylene, for example, high density polyethylene, medium density polyethylene, low density polyethylene, and linear low density polyethylene; polypropylene, for example isotactic polypropylene, syndiotactic polypropylene, mixtures of isotactic polypropylene and polypropylene. atactic; polybutylene, for example, poly (1-butene) and poly (2-butene) M polypentene, for example poly (1-pentene) and poly (2-pentene); poly (3-methyl-1-pentene); poly (4-methyl-1-pentene); and copolymers and mixtures thereof. Suitable copolymers include random and block copolymers prepared from two or more different unsaturated olefin monomers, such as ethylene / propylene and ethylene / butylene copolymers. Suitable polyamides include nylon 6, nylon 6/6, nylon 4/6, nylon 11, nylon 12, nylon 6/10, nylon 6/12, nylon 12/12, copolymers of caprolactam and alkylene oxide diamine and the like as well as mixtures and copolymers thereof. Suitable polyesters include polylactide and the polylactic acid polymers as well such as polyethylene terephthalate, polybutylene terephthalate, polytetramethyl terephthalate, polycyclohexylene terephthalate-1,4-dimethylene and isophthalate copolymers thereof as well as mixtures thereof. The particular polymer selected will depend on the intended use of the resulting non-woven fabric. In addition to the polymer, other additives, such as dyes, fillers and process aids may be present in the material which is to be formed in the fibers.

The selection of a particular attenuation fluid will depend on the polymer being extruded and other factors such as cost. In many cases, the attenuation fluid will be air. It is contemplated that the air available from a compressor can be used as the attenuation fluid. In some cases it may be necessary to cool the air in order to maintain a desired temperature difference between the heated polymer and the attenuation fluid. In all cases, however, it is essential that the minimum temperature difference desired be maintained in order to allow the reduced formation distances and obtain the advantages described above. In addition to air, other available inert gases can be used to attenuate in exceptional cases.

An insulating material can be used to protect the melted polymer from the attenuation fluid.

Any used material can be applied or fastened to the die tip in a desired manner and still withstand extrusion conditions. For example, materials such as porous silica borosilicate can be used. The thickness of the insulating layer will depend on the properties of the insulation material as well as the available space but will generally be at least about 0.5 millimeters and preferably at least 1 millimeter. When such insulating materials are used, lower polymer temperatures can be employed without increasing the danger of polymer solidification within the matrix. Conversely, when the insulating material is not used, increasing the temperature of the polymer or otherwise lowering the polymer viscosity will reduce the incidence of polymer solidification within the matrix.

The size of the meltblown matrix of the present invention also provides other advantages over conventional meltblown dies. The small width in the machine direction allows the meltblowing matrices to be placed in other non-woven fabric forming lines, so that new and different materials can be formed. Conventional melt blowing matrices have a width in the direction of the large machine, therefore the lines already having a non-woven production machine in place can not usually be modified to add a melt blowing process to the line. The reduced size improves entrapment of secondary air. The secondary air is the air which is not processed through the melting blow matrix. As a result, the blown nonwoven fabric produced from the fibers has improved qualities such as, for example, improved barrier properties and improved filtration properties. In addition, the small width in the machine direction allows several banks of blow molds to be placed in series along the machine direction. This can be beneficial to have several melt blow banks in the machine direction to produce a high weight basis material or to create a gradient fiber size structure, which is particularly useful in the production of filter materials .

Although the embodiments of the invention described herein are presently preferred, various modifications and improvements can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that fall within the meaning and range of equivalents are intended to be encompassed therein.

Claims (19)

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

1. A melt blowing matrix comprising: to. a body of matrix; b. a die tip comprising an upper side, a lower side, a first side and a second side, wherein the top side is mounted to the die body, the bottom side is opposite the top side, the first side and the second side side each extend from the upper side to the bottom side, the first side and the second side are opposite each other; c. a first air plate, wherein a part of the first air plate is in contact with the first side of the die tip and a series of ducts are formed by the first side of the die tip and the first air plate : Y d. a second air plate wherein a part of the second air plate is in contact with the second side of the die tip and a series of ducts are formed by the second side of the die tip and the second air plate.

2. The meltblown matrix as claimed in clause 1, characterized in that the die body further comprises a mounting plate, wherein the die tip and the first and second air plates are shown on the mounting plate .

3. The meltblown matrix as claimed in clause 1 or 2, characterized in that the first side of the matrix tip and the second side of the matrix tip each have a surface comprising a series of highlighted portions which extend from the upper side of the die tip towards the bottom side of the die tip defining a series of channels on each side of the die tip extending from the top side to the die tip towards the side bottom of the die tip and the first plate makes contact with at least a portion of the protruding portions of the first side of the die tip and the second air plate is in contact with at least a portion of the highlighted portions from the second side of the matrix tip.

4. The meltblown matrix as claimed in clause 2 or 3, characterized in that the die tip is mounted on the mounting plate with mounting means which extend from the mounting plate into the tip of the die. matrix.

5. The meltblown matrix as claimed in clause 2, characterized in that the first air plate and the second air plate are mounted with the mounting means on the mounting plate.

6. The meltblown matrix as claimed in clause 2 or 3, characterized in that the matrix body comprises an inlet for a material to be formed into fibers and an outlet for the attenuation fluid which attenuates the fibers.

7. The meltblown matrix as claimed in clause 2 or 3, characterized in that the mounting plate has a series of ducts which allow the attenuation fluid to flow from the matrix body to the series of ducts formed by the duct. the first and second air plates and the first and second sides of the die tip.

8. The meltblown matrix as claimed in clause 2 or 7, characterized in that the mounting plate comprises a distribution chamber which provides a path for a material to be formed into fibers from the matrix body to the tip of matrix where the distribution chamber has a non-linear course in the direction transverse to the machine.

9. The meltblown matrix as claimed in clause 8, characterized in that the non-linear course of the distribution chamber comprises a serpentine shape.

10. The meltblown matrix as claimed in clause 8, characterized in that the die tip further comprises a breaker plate / filter assembly, a series of polymer ports, and a pond chamber wherein the polymer ports they provide trajectories for a material to be formed into fibers from the breaker plate and a filtration assembly to the pond chamber.

11. The meltblown matrix as claimed in clause 10, characterized in that it also comprises a series of capillary vessels which connect the pond chamber to an outlet of the matrix tip.

12. The meltblown matrix as claimed in clause 11, characterized in that the die tip comprises two pieces, an upper part and a lower part, wherein the upper part comprises the filter / breaker plate assembly and the series of polymer ports and the lower part comprises the polymer pond chamber, the capillary vessel series and the matrix tip outlet.

13. The meltblown matrix as claimed in clause 1, characterized in that the meltblown tip has an overall width in the machine direction of between 5 and 12 centimeters.

14. A process for producing a non-woven fabric comprising generating fibers with the meltblown matrix of clause 1.

15. A melt blowing matrix comprising: to. a body of matrix; b. a die tip mounted on the die body; c. a first air plate mounted to the die body; d. a second air plate mounted on the die body; Y e. a distribution chamber which provides a path for a material to be formed in the fibers from the matrix body to the matrix tip in where the distribution chamber has a non-linear course in the direction transverse to the machine.

16. The meltblown matrix as claimed in clause 15, characterized in that it comprises a mounting plate, wherein the die tip and the first and second air plates are mounted on the mounting plate and the distributor chamber is located on the mounting plate.

17. The meltblown matrix as claimed in clause 16, characterized in that the non-linear course of distribution of the chamber comprises a serpentine shape.

A melt blowing matrix comprising: to. a body of matrix; b. a die tip mounted on the die body, c. a first air plate mounted on the die body; Y d. a second air plate mounted on the die body, where the meltblown matrix has a global width in the machine direction of less than 16 centimeters.

19. The meltblown matrix as claimed in clause 18, characterized in that the meltblown matrix has an overall width in the machine direction of between 5 and 12 centimeters. R E S U E N The present invention provides a meltblown matrix which has a considerably smaller width in the machine direction of the meltblown process as compared to commercially used and conventional meltblown dies. The meltblown matrix of the present invention has a. a body of matrix, b. a die tip mounted on the die body; c. a first of air mounted on the body of. matrix; and d. a second air plate mounted in the die body. In addition, the small size of the meltblown matrix of the present invention provides advantages over the conventional meltblown matrix including improved airborne.