Tube for multi-row coaxial melt-blowing system

Abstract

There is provided a tube (1) for a multi-row coaxial meltblown system, the tube defining a development axis (1a) and comprising at least one closed inner surface (2) extending around the development axis (1a) and defining a plurality of mutually identical profiles (3) arranged in succession along the development axis (1a); wherein the cross-section (3) is defined in a cross-sectional plane (1b) perpendicular to the development axis (1a), the cross-section defining a first extension region on the cross-sectional plane (1b) and being inscribed to a circle defined on the cross-sectional plane (1b), and the circle defining a second extension region on the cross-sectional plane (1b); and wherein the first extension region is less than 90% of the second extension region.

Description

Technical Field

[0001] The invention relates to a tube for a multi-row coaxial melt-blown system.

[0002] In particular, the invention relates to an element that is part of a system designed to enable the manufacture of extruded polymer filaments intended to produce, directly or indirectly, nonwovens (also called TNTs). Background Art

[0003] As we all know, non-woven fabric or TNT is an industrial product similar to fabric, but its production process is different from weaving and knitting.

[0004] Thus, in nonwovens, the fibers are randomly arranged without any discernible ordered structure, whereas in woven fabrics, the fibers typically have two main orthogonal directions, often called weft and warp.

[0005] Currently, a variety of products containing TNT are produced, depending on the production technology used, which is mainly related to the intended use of the product.

[0006] In particular, high-quality TNT is used in hygiene and cleaning products, while low-quality TNT is mainly used in geotextiles.

[0007] From a technical point of view, nonwoven fabrics (the English term is called "nonwoven fabric") can generally be divided into spunlace fabrics, spunbond fabrics and meltblown fabrics.

[0008] In meltblowing technology, multi-row coaxial meltblowing systems or multi-row coaxial meltblowing systems are particularly known.

[0009] Generally, these systems draw the polymer out of a row of tubes by passing air coaxially through the outside of the tubes and pushing the fibers downward.

[0010] In particular, the multi-row coaxial meltblowing system includes components defining coaxial holes arranged in a row and adapted to receive at least a portion of the above-mentioned tubes, which pass coaxially within the holes to allow diffusion of polymer fluid while allowing air or gas to diffuse from at least a portion of the holes.

[0011] Typically, these systems include a device called a spin pack, which is composed of several different components designed to interact with each other. Typically, the spin pack consists of a spinneret and a diffuser, which includes one or more components called air plates.

[0012] Furthermore, the spinneret itself may be connected to the cone and / or the interrupter plate.

[0013] If present, the interrupter plate is also connected to the extrusion head, which is designed to deliver at least the polymer fluid and possibly air or gas under pressure to the spin pack. The interrupter plate and cone have essentially the same features as the interrupter plates and cones used in spunbond and meltblown technologies.

[0014] However, a multi-row coaxial meltblowing system including a spin pack does not include a diffuser having a support adapted to support an air knife, does not have a tip, and does not have a simple die designed only for polymer outflow.

[0015] In a multi-row coaxial meltblowing system, the spinneret is essentially a support device that holds the tubes through which the polymer filaments are discharged. Therefore, a diffusion device is connected to the spinneret and includes an intermediate plate or air plate that allows the tubes to pass and allows air or other pressurized gas to flow out, and an outer hood or outer air plate that is usually divergent in shape, through which the polymer filaments flow out and are pushed downward by the air before reaching the conveyor belt present in any nonwoven manufacturing plant.

[0016] The prior art described has some significant disadvantages.

[0017] In particular, the tubes present in the prior art multi-row coaxial meltblown systems comprise only circular outlets, which does not allow the production of nonwoven fabrics having different mechanical properties.

[0018] Thus, the only function of the conventional tube is to guide the polymer along the axis. Summary of the invention

[0019] In this case, the technical task of the present invention is to design a tube for a multi-row coaxial meltblown system which is able to overcome at least some of the listed disadvantages.

[0020] As part of this technical task, an important object of the present invention is to provide a tube for a multi-row coaxial meltblown system that is capable of producing nonwoven fabrics with different mechanical properties.

[0021] Another important object of the present invention is to produce a tube for a multi-row coaxial meltblowing system that has increased functionality associated with conventional tubes.

[0022] Furthermore, another task of the present invention is to make a tube for a multi-row coaxial meltblowing system that allows to apply internal stress to the polymer exiting from the die without using additional components.

[0023] Technical tasks and specific goals are achieved with tubes for multi-row coaxial meltblown systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The features and advantages of the present invention will become apparent through a detailed description of preferred embodiments of the present invention with reference to the accompanying drawings, in which:

[0025] Figure 1 A tube for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the shape of the outer surface is similar to the inner surface;

[0026] Figure 2a A cross-sectional view on a cross-sectional plane of a tube of a multi-row coaxial meltblowing system according to the present invention having a first concave profile is shown, wherein the convex portion is shown in dotted lines;

[0027] Figure 2b is a cross-sectional view on a cross-sectional plane of a tube of a multi-row coaxial meltblowing system according to the present invention having a second concave profile, wherein a convex portion is shown in dotted lines;

[0028] Figure 2c A cross-sectional view on a cross-sectional plane of a tube of a multi-row coaxial meltblowing system according to the present invention having a third concave profile is shown, wherein the convex portion is shown in dotted lines;

[0029] Figure 2d A cross-sectional view on a cross-sectional plane of a tube of a multi-row coaxial meltblown system according to the present invention having a fourth convex profile is shown;

[0030] Figure 2e A cross-sectional view on a cross-sectional plane of a tube of a multi-row coaxial meltblown system according to the present invention having a fifth convex section is shown;

[0031] Figure 2f is a cross-sectional view on a cross-sectional plane of a tube of a multi-row coaxial meltblowing system according to the present invention having a sixth concave profile, wherein a convex portion is shown in dotted lines;

[0032] Figure 2g A cross-sectional view on a cross-sectional plane showing a seventh concave section of a tube for a multi-row coaxial meltblowing system according to the present invention, wherein the convex portion is shown in dotted lines;

[0033] Figure 2h A cross-sectional view on a cross-sectional plane of a tube of a multi-row coaxial meltblowing system according to the present invention having an eighth concave profile is shown, wherein the convex portion is shown in dotted lines;

[0034] Figure 2i A cross-sectional view on a cross-sectional plane of a tube of a multi-row coaxial meltblowing system according to the present invention having a ninth concave profile is shown, wherein the convex portion is shown in dotted lines;

[0035] Figure 2jis a cross-sectional view on a cross-sectional plane of a tube of a multi-row coaxial meltblowing system according to the present invention having a tenth concave profile, wherein a convex portion is shown in dotted lines;

[0036] Figure 3a A perspective view of a tube for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the outer surface is cylindrical and the cross section has Figure 2a The shape shown;

[0037] Figure 3b A perspective view of a tube for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the outer surface is cylindrical and the cross section has Figure 2b The shape shown;

[0038] Figure 3c A perspective view of a tube for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the outer surface is cylindrical and the cross section has Figure 2c The shape shown;

[0039] Figure 3d is a perspective view of a tube for a multi-row coaxial meltblown system according to the present invention, wherein the outer surface is cylindrical and the cross section has Figure 2d The shape shown;

[0040] Figure 3e A perspective view of a tube for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the outer surface is cylindrical and the cross section has Figure 2e The shape shown;

[0041] Figure 3f A perspective view of a tube for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the outer surface is cylindrical and the cross section has Figure 2f The shape shown;

[0042] Figure 3g A perspective view of a tube for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the outer surface is cylindrical and the cross section has Figure 2g The shape shown;

[0043] Figure 3h is a perspective view of a tube for a multi-row coaxial meltblown system according to the present invention, wherein the outer surface is cylindrical and the cross section has Figure 2h The shape shown;

[0044] Figure 3i A perspective view of a tube for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the outer surface is cylindrical and the cross section has Figure 2i The shape shown;

[0045] Figure 3jA perspective view of a tube for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the outer surface is cylindrical and the cross section has Figure 2j The shape shown;

[0046] Figure 4a A cross-sectional view of a tube bank comprising a plurality of tubes for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the shape of the outer surface is similar to the inner surface, and the tubes have the same shape in the same column and alternating shapes in the same row;

[0047] Figure 4b is a cross-sectional view of a tube bank including a plurality of tubes for a multi-row coaxial meltblowing system according to the present invention, wherein the shape of the outer surface is similar to the inner surface, and the tubes have the same shape;

[0048] Figure 4c showing a cross-sectional view of a tube bank comprising a plurality of tubes for a multi-row coaxial meltblowing system according to the present invention, the tubes being arranged in columns with one another and alternating with columns of tubes defining a circle wherein the outer surface is shaped similarly to the inner surface;

[0049] Figure 4d A cross-sectional view of a tube bank comprising a plurality of tubes for a multi-row coaxial meltblowing system according to the present invention is shown, wherein the shape of the outer surface is similar to the inner surface, and the tubes have the same shape in the same column and have alternating concave and convex shapes in the same row, respectively;

[0050] Figure 5a shows a cross-sectional view of a tube stack according to the present invention, the tube stack comprising a plurality of tubes for a multi-row coaxial meltblowing system, wherein the outer surface is cylindrical and the tubes have the same concave shape;

[0051] Figure 5b is a cross-sectional view of a tube bank comprising a plurality of tubes for a multi-row coaxial meltblowing system according to the present invention, wherein the outer surface is cylindrical and the tubes have the same triangular convex shape;

[0052] Figure 5c Represents a cross-sectional view of a tube bank comprising a plurality of tubes for a multi-row coaxial meltblowing system according to the present invention, wherein the outer surface is cylindrical and the tubes have the same convex rectangular shape;

[0053] Figure 5d shows a cross-sectional view of a tube bank comprising a plurality of tubes for a multi-row coaxial meltblowing system according to the present invention, wherein the outer surface is cylindrical and the tubes have the same concave star shape;

[0054] Figure 6ashows a cross-sectional view of a tube stack according to the present invention, the tube stack comprising a plurality of tubes for a multi-row coaxial meltblowing system, wherein the outer surface is cylindrical, the tubes have the same concave shape, and the tubes are arranged alternately with tubes having a circular shape in a checkerboard pattern;

[0055] Figure 6b is a cross-sectional view of a tube bank including a plurality of tubes for a multi-row coaxial meltblowing system according to the present invention, wherein the outer surface is cylindrical, the tubes have two different concave shapes, and the tubes of different shapes are arranged alternately in a checkerboard pattern;

[0056] Figure 6c A cross-sectional view showing a tube stack according to the present invention, the tube stack comprising a plurality of tubes for a multi-row coaxial meltblowing system, wherein the outer surface is cylindrical, the tubes have two different shapes, concave and convex, and the tubes of different shapes are arranged alternately in a checkerboard pattern; and

[0057] Figure 6d A cross-sectional view of a tube stack according to the present invention is shown, the tube stack comprising a plurality of tubes for a multi-row coaxial meltblowing system, wherein the outer surface is cylindrical, the tubes have two different shapes, concave and convex, and the tubes of different shapes alternate in a checkerboard pattern. DETAILED DESCRIPTION

[0058] In this document, dimensions, values, shapes and geometrical references (such as perpendicularity and parallelism) when associated with terms such as "approximately" or other similar terms such as "substantially" or "essentially" should be understood to be within measurement errors or inaccuracies due to production and / or manufacturing errors, especially within slight deviations of the values, measurements, shapes or geometrical references associated with them. For example, when associated with a value, these terms preferably represent a deviation of no more than 10% of the value itself.

[0059] Furthermore, terms such as “first,” “second,” “upper,” “lower,” “primary,” and “secondary” when used do not necessarily indicate an order, relationship priority, or relative position, but may simply be used to distinguish different components.

[0060] Unless otherwise indicated, as will appear from the following discussion, terms such as "process," "compute," "determine," "calculate," and "compute" are considered to refer to the action and / or process of a computer or similar electronic computing device that manipulates and / or transforms data represented as physical quantities (e.g., electrical quantities in a computer system's registers and / or memories) into other data similarly represented as physical quantities in a computer system, registers, or other storage, transmission, or display device.

[0061] Unless otherwise stated, the measurements and data reported in this article should be deemed to have been made in International Standard Atmosphere (ICAO Standard Atmosphere ISO 2533:1975).

[0062] With reference to the accompanying drawings, a tube for a multi-row coaxial meltblowing system according to the present invention is generally indicated by numeral 1.

[0063] The tube 1 is essentially an element of substantially elongated shape comprising a cavity through which liquid polymer can flow to allow, for example, extrusion from a die.

[0064] The tube 1 thus defines a development axis 1 a.

[0065] The development axis 1a is substantially the axis about which the tube 1 develops. Furthermore, the development axis 1a is the axis along which the liquid polymer can flow and, therefore, the development axis is the axis along which the cavity defined by the tube 1 develops.

[0066] The tube 1 thus comprises at least one inner surface 2 .

[0067] The inner surface 2 is substantially closed. Furthermore, the inner surface develops around the development axis 1a, and in fact faces the development axis.

[0068] The inner surface 2 thus closes the cavity.

[0069] Furthermore, the tube 1 defines a plurality of sections 3. The sections 3 are identical to one another. Furthermore, the sections are arranged successively along the development axis 1a.

[0070] The section plane 3 is thus substantially formed by the inner surface 2 along the development axis 1 a and determines the general shape of the cavity.

[0071] In particular, preferably, the section 3 is defined on the sectional plane 1 b.

[0072] Preferably, the section plane 1 b is perpendicular to the development axis 1 a. The section plane 1 b is thus substantially a virtual plane defining the section 3 formed by the inner surface 2 on itself by cutting the tube 1 perpendicularly to the development axis 1 a.

[0073] Furthermore, the section 3 defines a first extension area. The extension area is a two-dimensional spatial portion contained within the section 3.

[0074] Therefore, preferably, the section 3 can be inscribed in a circle. The circle is also defined on the section plane 1b. Naturally, the circle is a simple virtual geometric element, in which the section 3 can be geometrically inscribed.

[0075] Furthermore, the circle defines a second extension area on the cross-sectional plane 1b. Therefore, since the second extension area is determined by the two-dimensional space contained within the circle, the formula A=π*r can be used as known. 2 to calculate.

[0076] Advantageously, the section 3 does not correspond to the shape of this circle.

[0077] In fact, advantageously, the first area of ​​extension is less than 90% of the second area of ​​extension. Even more particularly, preferably, the first area of ​​extension is less than 60% of the second area of ​​extension.

[0078] Therefore, the profile 3 can be made according to different embodiments.

[0079] For example, the cross section 3 may be a convex figure. As is well known, a convex figure refers to a figure in which a line segment connecting any two points in the figure is completely contained within the figure itself.

[0080] Thus, if the cross section 3 is convex, preferably the cross section defines a first dimension 3a and a second dimension 3b.

[0081] The first dimension 3a is substantially the largest dimension determined in one direction of the cross section 3. The second dimension 3b is also the largest dimension in a direction perpendicular to the first dimension 3a.

[0082] Preferably, the second dimension 3b is smaller than 90% of the first dimension 3a.

[0083] More specifically, the second dimension 3b may be smaller than 60% of the first dimension 3a.

[0084] Furthermore, dimensions may refer to well-defined geometric sections 3 .

[0085] For example, Figure 2d As shown, the convex cross section 3 can have a shape approximately equal to an equilateral triangle, or as Figure 2e As shown, it can have an approximately rectangular shape, the sides of which may be slightly curved.

[0086] Naturally, in the case of a triangle, the first dimension 3a may be given by the height, while the second dimension 3b may be given by the base where the height lies. In the case of a rectangle, the dimensions 3a and 3b may correspond to the respective sides.

[0087] In other embodiments, the cross-section 3 may instead be concave. Contrary to convexity, concavity of a figure is evident when there is at least one line segment connecting a pair of points of the figure, which line segment is not completely contained within the figure itself.

[0088] Thus, if the profile 3 is concave, preferably the profile comprises at least one convex portion 30. The convex portion 30 is a portion of the concave profile 3 which can be identified within the profile 3 so as to be at least partially delimited and present a convex character.

[0089] Thus, like the convex profile 3, the convex portion 30 may define a third dimension 30a and a fourth dimension 30b.

[0090] The third dimension 30a is substantially the maximum dimension determined in one direction of the raised portion 30. The fourth dimension 30b is also the maximum dimension in a direction perpendicular to the third dimension 30a.

[0091] Preferably, the fourth dimension 30b is less than 90% of the third dimension 30a.

[0092] More specifically, the fourth dimension 30b may be less than 60% of the third dimension 30a.

[0093] As previously mentioned, the size may refer to a well-defined geometric projection 30. For example, Figure 2h As shown, the raised portion 30 of the cross section 3 may have a substantially triangular shape, or may be substantially triangular in shape. Figure 2g and 2j As shown, it has an approximately rectangular shape, which may be Figure 2a One side is tilted as shown, or even as Figure 2b-Figure 2c Trapezoid shape shown.

[0094] Naturally, in the case of a triangle, the first dimension 3a may be given by the height, while the second dimension 3b may be given by the base where the height lies. In the case of a rectangle, the dimensions 3a and 3b may correspond to the respective sides.

[0095] More generally, the concave profile 3 may be formed by two or more convex portions 30 intersecting each other. Thus, the concave profile 3 may define a cross shape having three to five apexes. Figure 2a and Figure 2c Three of them, or Figure 2f and Figure 2i Four of them, or even Figure 2b and Figure 2j Five of them.

[0096] In addition to what has been described, the tube 1 may also comprise an outer surface 4 .

[0097] The outer surface 4 is also closed. In addition, the outer surface 4 develops around the inner surface 2. Therefore, the outer surface 4 surrounds the inner surface 2.

[0098] Furthermore, preferably, the outer surface 4 facing the outside of the tube 1 and therefore not in contact with the cavity is connected to the inner surface 2 by a wall 5 .

[0099] The wall 5 is therefore surrounded by the surface 2 and the surface 4 , which surfaces thus define a face opposite the wall 5 .

[0100] Therefore, if Figure 3a-3j , Figure 5a-5d and Figure 6a-6d As shown, the outer surface 4 can be cylindrical, or the outer surface 4 can be similar to the shape of the inner surface 2. In this way, for example Figure 1 and Figure 4a-4d As shown, the surfaces 2 and 4 determine a constant thickness of the wall 5 .

[0101] Naturally, the tube 1 can be used together with other tubes to form a tube set for use in a system.

[0102] Therefore, the present invention also comprises a tube group comprising a plurality of tubes 1 .

[0103] In various embodiments, such as Figure 5a-5d As shown, the set may comprise a plurality of tubes 1 , all defining the same cross section 3 .

[0104] Or, if Figure 4a-4d and Figure 6b-6d As shown, the set may comprise a plurality of said tubes 1 defining respective cross-sections 3 that are different from one another.

[0105] Optionally, again, as Figure 4c and Figure 6a As shown, the set may comprise a plurality of tubes 1 and a plurality of tubes defining a circular cross-section, ie having a conventional cross-section according to the prior art.

[0106] Naturally, the present invention also comprises a multi-row coaxial meltblowing system comprising the tube bank described above according to various possible embodiments.

[0107] As described above in terms of structure, the operation of the tube 1 for a multi-row coaxial meltblowing system is substantially similar to that of any tube of the prior art in that it allows the polymer fluid to be conveyed along the development axis 1a.

[0108] However, the tube 1 for a multi-row coaxial meltblowing system according to the present invention achieves important advantages.

[0109] In fact, the tube 1 used in a multi-row coaxial meltblowing system allows the production of nonwoven fabrics having different mechanical properties than those produced with conventional tubes.

[0110] Thus, the tube 1 for a multi-row coaxial meltblown system has increased functionality associated with conventional tubes.

[0111] In particular, the tube 1 for a multi-row coaxial meltblowing system allows for the introduction of internal stresses into the polymer exiting the die without the use of additional components.

[0112] The present invention is susceptible of various modifications which are within the scope of the inventive concept.

[0113] Within this scope, all the details may be replaced by equivalent elements and the materials, shapes and dimensions may be of any kind.

Claims

1. A tube (1) for a multi-row coaxial meltblown system, the tube (1) defining a development axis (1a) and comprising at least one closed inner surface (2), the inner surface (2) extending around the development axis (1a) and defining a plurality of mutually identical cross sections (3), the cross sections (3) being arranged in sequence along the development axis (1a); - the section (3) is defined on a cross-sectional plane (1b) perpendicular to the development axis (1a), the section (3) defines a first extension area on the cross-sectional plane (1b) and can be inscribed in a circle defined on the cross-sectional plane (1b), and the circle defines a second extension area on the cross-sectional plane (1b); The tube (1) is characterized in that - said first area of ​​extension is less than 90% of said second area of ​​extension.

2. The tube (1) according to claim 1, wherein The first extension area is less than 60% of the second extension area.

3. A tube (1) according to claim 1 or 2, wherein: The cross section (3) is convex and defines at least a first dimension (3a) and a second dimension (3b) perpendicular to the first dimension (3a), wherein the second dimension (3b) is less than 90% of the first dimension (3a).

4. The tube (1) according to claim 3, wherein: The second dimension (3b) is less than 60% of the first dimension (3a).

5. The tube (1) according to claim 1 or 2, wherein: The cross section (3) defines an approximately equilateral triangle shape or an approximately rectangular shape.

6. The tube (1) according to claim 1 or 2, wherein: The cross-section (3) is concave and includes at least one raised portion (30) identifiable within the cross-section (3), such that the raised portion (30) is at least partially bounded by the cross-section (3), and the raised portion (30) defines at least a third dimension (30a) and a fourth dimension (30b) perpendicular to the third dimension (30a), wherein the fourth dimension (30b) is less than 90% of the third dimension (30a).

7. A tube (1) according to claim 6, wherein The fourth dimension (30b) is less than 60% of the third dimension (30a).

8. A tube (1) according to claim 6 or 7, wherein: The cross section (3) is formed by two or more intersecting raised portions (30).

9. The tube (1) according to claim 1 or 2, wherein: The cross section (3) defines a cross having three to five points.

10. A tube (1) according to claim 1 or 2, comprising at least one closed outer surface (4), which extends around the inner surface (2) and is connected to the inner surface (2) via a wall (5), so that the inner surface (2) and the outer surface (4) define opposite faces of the wall (5), and the outer surface (4) is cylindrical, thereby determining a constant thickness of the wall (5).

11. A tube stack (10) for a multi-row coaxial meltblowing system, the tube stack (10) comprising at least one tube (1) according to any one of the preceding claims.

12. A tube group (10) according to claim 11, comprising a plurality of said tubes (1) all defining one and the same cross section (3).

13. A tube group (10) according to claim 11 or 12, comprising a plurality of said tubes (1) defining mutually different cross sections (3).

14. The tube group (10) according to claim 11 or 12, comprising a plurality of said tubes (1) and a plurality of tubes, each tube of said plurality of tubes defining a circular cross-section.

15. A multi-row coaxial meltblowing system comprising a tube group (10) according to any one of claims 11-14.

Images