Textile product, textile press mold, and press molding method for textile product

Abstract

The present invention relates to a method for pressing a textile product using a press pad device (2) and stamp devices (3, 4) at high pressure and temperature, characterized in that the textile product (1) comprises a bottom portion (11) and an edge portion (10), and the stamp device (3, 4) comprises two stamp members (3, 4), a first stamp member (3) forming at least the bottom portion (11) and a second stamp member (4) forming the edge portion (10). The present invention also relates to the textile press molds (2, 3, 4) and the textile product (1).

Description

[Technical Field]

[0001] The present invention relates to a method for pressing textiles at high pressure and temperature, using a press pad device and a stamp device to carry out the method. [Background technology]

[0002] Textile products can be made by pressing a web or sheet of fibers. Combinations of natural fibers (e.g., wood pulp fibers), synthetic fibers (e.g., polyolefin fibers, such as those made from polyethylene), and other additives, such as binders or dyes, are typically considered. For many applications, it is preferred that such webs essentially comprise only natural fibers, with or without additives. Typical processing conditions are 150-250°C and pressures of 100-10,000 bar (200-2,000 bar). The moisture content can typically be less than 20%.

[0003] The textile product may be in the form of a hollow product, for example a package or closure (lid, screw cap, etc.), but may also be a flat product. The product may be formed from a web of material and punched / cut in connection with the formation. For example, it may be completely or partially separated from the web to allow for deeper molding. This exposure is usually done by cutting the material into a shape that corresponds to the final shape. Typically, for example, a circle is cut to form a circular package.

[0004] Press forming is usually performed using two tools, both the outer tool (pad) and the inner tool (stamp) which can consist of several parts that allow the ejection of the finished product. Usually, the pad opens while the stamp contracts. The piston, part of the piston, or part of the pad can also be made of a compressible material, which usually allows for a greater vertical compressive force against the sides of the cavity due to the tool material taking shape during compression.

[0005] Examples of the known methods described above are given in EP 3736099 and WO 2020 / 165780.

[0006] A rigid board container is also known from US Pat. No. 4,606,496. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European Patent No. 3736099 [Patent Document 2] International Publication No. 2020 / 165780 [Patent Document 3] U.S. Patent No. 4,606,496 [Patent Document 4] Swedish Patent Application Publication No. 2151225-6 Summary of the Invention

[0008] The object of the present invention is to optimize in at least some applications the production of cup-shaped press mold textile products, which is achieved by the method defined in claim 1 and / or the textile press mold defined in claim 12.

[0009] With the present invention, a more homogeneous product can be achieved which can result in obtaining a more uniform quality of the cup-shaped press mold textile product.

[0010] In the following, the invention will be explained with reference to schematic preferred embodiments of a press tool according to the invention by describing a preferred example press tool in a schematic manner. [Brief explanation of the drawings]

[0011] [Figure 1] 1 shows a schematic cross-sectional view of a fiber press mold when carrying out the method according to claim 1 as described above. [Figure 2]A further preferred embodiment is highlighted when threaded press mold textiles with protrusions are created. Figure 2 provides a cross-sectional view of the mold product from the side. This preferred embodiment provides the possibility of sealing, for example, by using a screw-on cap with a groove (compatible with the protrusion, i.e., thread, which may be present on the inside or outside) to provide a sealed or partially sealed container, such as a cup. Also, a screw-on cap that can fit onto a container can be provided using an approach similar to that shown in Figure 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] In Figure 1, a textile press mold is shown, which comprises a press pad device 2 and a stamp device 3 for forming a cup-shaped textile product 1. The cup-shaped textile product 1 comprises a side wall 12 between a top edge 10 and a bottom 11. The stamp device 3 may be a one-piece solid structure or may be separable into two or more pieces. The device may also be foldable.

[0013] The press pad device 2 comprises a body 20 in which a cavity (or recess) 22 is disposed. The cavity 22 includes a bottom 23 and a sidewall 24. The body 20 may be a solid structure or may be divisible into two or more pieces.

[0014] The stamp member 3 has a body 30 adapted to fit within the cavity 22 so that a gap can be formed between its side 34 and the side wall 24 of the cavity, thereby achieving the desired thickness t12 of the side wall 12 of the textile product.

[0015] The press molding method described in claim 1 also includes positioning the upper edge (10) of the textile product (1) within the cavity (22) of the press pad device (2) after forming at least the bottom part (11), and preferably positioning the entire upper edge (10) below the upper surface of the body (20) of the press pad device (2).

[0016] The material of the textile product 1 may comprise wood, natural fibres made from straw, natural fibres such as bagasse, and / or recycled fibres, and / or recycled wood fibres or a combination thereof, preferably natural wood fibres, most preferably virgin natural wood fibres, or recycled wood fibres may be preferred when sustainability is important.

[0017] Furthermore, the amount of water in the pre-cut blanks (eg, circles) before pressing will not exceed 20% of the weight of the fibers.

[0018] The material of the textile 1 may also include pre-expanded microspheres and / or expandable microspheres.

[0019] The material of the textile product 1 may also include a fiber mat produced by airlaid technology and / or a fiber mat produced by wetlaid technology.

[0020] The material of the textile product 1 may also include a paper sheet, preferably having a moisture content of about 4 to about 25%, most preferably about 7 to about 15%.

[0021] When using a mold to press-mold the textile 1, a pre-cut blank (not shown) is introduced into the cavity 22 of the press pad device 2. The stamp member 3 is then subjected to a force F1, lowering it into the cavity 22, which then forms the textile. During production, high temperatures are used, and high pressure is applied by the press pad device 2 and stamp device 3, and optionally by an additional stamp device 4, which may be a separate stamp device or may be part of the stamp device 3 (i.e., creating a single entity), to form the textile 1. The mold temperature may be about 80 to about 250°C, preferably about 150 to about 250°C, and the pressure applied by the stamp 3 and additional stamp device 4 is at least 200 bar. Furthermore, the pressure may be applied so as to be about 500 to about 1000 bar. The press pad device 2 may also be one piece, or it may be made from two or more pieces, with one piece being preferred.

[0022] Preferably, the first stamp member 3 is positioned (e.g., controlled by a sensor) to stop pressing at a given distance relative to the position of the press pad device 2 so that the bottom 11 reaches a given thickness t11.

[0023] As is generally known, the cup-shaped product has a substantially vertical wall 12, the term "substantially vertical" being interpreted broadly.

[0024] As shown in FIG. 1 , the substantially vertical wall 24 of the pad device 2 is positioned such that the angle α relative to the vertical is greater than the corresponding angle β of the substantially vertical wall of the stamp device 3, thereby forming a gap that branches (at least partially) upward to form the substantially vertical wall 12.

[0025] In Fig. 1, when α and β are indicated, they also indicate the mean surface lines that give rise to the angles α and β. The angle β may even be parallel to the y-axis of Fig. 1. In Fig. 2, the mean surface lines also appear as protruding threads 35, as mentioned above. At the same time, depressions 36 corresponding to the threads are formed, giving rise to valleys. As explained above, when a container is threaded using the method of claim 1, these mean surface lines are more pronounced (as can be seen in Fig. 2).

[0026] With this design, a more uniform density can be achieved in the generally vertical wall portion 12 due to the dynamics that occur during pressing.

[0027] The dynamics described above are explained in more detail below. When forming a similar cup-like or other 3D shape from a flat object, the material is forced into a new shape. Specifically, when forming an object that resembles something between a circular or oval cylinder with a bottom and sides and a box from a flat blank, the material must stretch or compress. If the bottom of the structure does not stretch but essentially retains its original shape, the sides must compress.

[0028] Specifically, in the forming operation, where a felt-like soft material is formed into a shape similar to that described above, for subsequent sintering to form the shape, the forming process includes three main steps: a folding step, a forming step, and a sintering step.

[0029] Draping is the process by which the material is folded into the cavities 22 of the pad 2, for example by using a stamp 3 or another tool, i.e. by pressing down on the material, hence the operation is called draping.

[0030] The forming step is when the product is given its shape as the stamp 3 pushes the material towards the sides 24 and bottom 23 of the cavity 22. Here, the material moves within the plane of the formed object, locally transferring mass from areas with more material to areas with less material, thus locally homogenizing the density of the material.

[0031] In a sintering process, materials are typically fused in place using heat, high pressure, sintering, and / or chemical reactions.

[0032] If the movement of the material is restricted, for example, the density may vary depending on the material accumulated by particles or fibers (rather than the degree of melting for low viscosity), the density change of the material will depend on the amount of material that was originally folded into a given section of the cavity 22 that forms the object, and in terms of volume, made possible by the open space between the pad 2 and the stamp 3.

[0033] There are several reasons to aim for a uniform distribution of density in the formed product: on the one hand, the mechanical properties depend on the density of the sintered material; on the other hand, the pressure exerted by the forming process also depends on the local density; low density can risk an insufficient sintering process, and high pressure reactions can create friction in the forming operation, risking tearing or distorting the material.

[0034] Local density and density variations can act by allowing more volume to pass through as needed and / or by controlling the folding process.

[0035] In one example, a circular blank is formed into a cup-shaped object, accumulated by its base 11 and wall 12. The average amount of material at a given location on the wall 12 is a function of its height from the bottom of the cylinder. If a constant gap size is used, as the height increases, the original protrusion of the blank is distorted into a new protrusion on the formed object according to its geometric location. By compensating for this, the increase in volume between the sides 24, 34 of the two parts of the forming tool 2, 3 allows the density to be monitored and maintained more constant. In this way, the mechanical properties of the object, the process functionality, and the effectiveness of the sintering pressure can be improved. Typically, all of these functions are significantly improved when the density of all parts of the formed product is maintained within + / - 30% of the average density, or ideally + / - 10%.

[0036] For any given object and shape, the ideal function for the desired volume of the sidewall 12 can be calculated using the geometry, lateral position, and height from the bottom. According to the present invention, the average wall volume increases from the portion near the bottom 11 to the portion near the top edge 10. Thus, the wall thickness t122 ​​near the bottom 11 is smaller than the wall thickness t121 adjacent to the edge 10. At the top of the wall t121, it can preferably fall within a range of + / - 30% of t122(d+h) / d, where d is the width (e.g., diameter) of the bottom 11 and h is the height, i.e., the distance from the bottom 11 to the top edge 10. For low structures whose height (d+h) is approximately equal to d, the effect is negligible. For high structures, the effect is significant; for example, for d=30 and h=15 mm, the ideal average t121 can preferably be approximately 1.5 times larger than t122.

[0037] In one embodiment, design features such as indentations or protruding structures may be used to create volumetric changes in the structure wall. An example may be a screw-on cap in the general form of a cylinder, where the threads create indentations and protruding structures on the inside of the cap, while small grooves for gripping may create localized changes on the outside of the cap.

[0038] In such cases, the volume of the average cross-sectional area across the height of the wall can be used, and then the average cross-sectional area is compensated to achieve the increase in volume leading to the same density.

[0039] In the first part of the forming operation, i.e., when the blank is lowered into the mold cavity, the draping is folded and then compressed in sections along these folds. If the distance between the folds is too large, high-density areas may occur far from each other, and during the generation of sintering forces, internal movement of the material may make it impossible to achieve a sufficiently uniform density profile. In this context, basis weight may also be an important factor.

[0040] Several measures can be applied to improve the control of the folding structure, for example: -Make an indentation or crease in the blank to allow the fold to begin. -Make a cut in the blank so that the fold can begin. -Holds folds in place at critical locations when starting the draping portion of the process; - shaping the rim of the blank where the folding begins, -Shape the top of the cavity rim so that the fold starts where you want it.

[0041] Furthermore, in some applications, the present invention may be advantageously combined with the use of a second stamping element (not shown), as described in more detail in previously filed Swedish Patent Application No. 2151225-6, which is hereby incorporated by reference. Thus, when using this process, the entire pre-cut blank is pressed into the pad 2 and below its upper surface, and in a subsequent step, a second press tool can form the upper edge 10, resulting in a product with a predetermined upper edge 10. The second stamping element can be seen as creating a kind of reshaping. It can also help form inward or outward features with varying gap thickness or shape, such as embossments, reinforcements, or threads. An additional benefit is the ability to form surfaces with precise patterns or profiles. For example, it can achieve shapes that would be impossible if cutting were required to form the final product.

[0042] According to a preferred embodiment of the pressing method described above with respect to claim 1, a pressure (F2) may also be applied to the edge (10), preferably the same or different from F1, i.e. the pressure acting on the bottom (11).

[0043] According to a preferred embodiment of the press-molding method described above with respect to claim 1, protrusions, preferably threads and / or gripping bars, are embossed into the textile by embossing with a press pad device (2) and / or by using a stamp member (3). By doing so, a screw-on cap with a matching groove on the inside of a container made according to the method of claim 1 can be used for sealing. Alternatively, if a matching groove is present on the outside of a container made according to the method, this can be used for sealing. It may be preferred to use only the stamp member (3) to emboss the threads into a container made using the method. When such embossing is performed, the press pad device 2 and / or the stamp device 3 are adapted to provide the threads when using pressure and temperature as described above.

[0044] According to a preferred embodiment of the press-molding method described above with reference to claim 1, it also comprises a gasket member (not shown in any of the figures) applied to the bottom (23) of the stamp device (3), which forms an interior on top of the bottom (11). Preferably, the gasket member is at least partially elastic and compressible. At the same time, it may be the second stamp member (4) which forms the edge (10).

[0045] According to a preferred embodiment of the method described above with respect to claim 1, pre-expanded microspheres and / or expandable microspheres are added during the pressing or before the pressing begins, preferably the pre-expanded microspheres and / or expandable microspheres are added to the material before the pressing begins.

[0046] According to a preferred embodiment of the method described above with respect to claim 1, the pre-expanded and / or expandable microspheres are treated at about 50 to about 150°C, preferably about 50 to about 120°C, most preferably about 60 to about 100°C, thus providing a dry content of about 50 to about 70% and thus providing an expanded or foamed product.

[0047] According to a preferred embodiment of the method as described above with reference to claim 1, steam is added during the step for expanding the material.

[0048] The moisture content (described with respect to the specific embodiments above) provides advantages during pressing (see the first aspect of the invention, i.e. claim 1). Preferably, the moisture is added before pressing of the materials (i.e. raw materials) is achieved.

[0049] Important features of caps, lids, or similar structures made from fibers include compressibility and shape stability. By adding pre-expanded and / or expandable microspheres to the fiber network, the ability of the material to recover its shape after compression, the so-called bounce-back force, is increased. This can also be expressed as influencing the viscoelastic characteristics of the material. As a result, the tendency for time-dependent deformation, the so-called "creep deformation," is reduced. The sealing spheres can be added in different ways, for example, to paper sheets (materials). Pre-expanded and / or expandable microspheres can be added.

[0050] The microspheres can be added at different stages of the manufacturing process. The microspheres can be added before the fiber mat is manufactured, but preferably they are added in connection with the fiber mat's manufacture. This can be done while the fiber mat is dry or wet. Alternatively, the microspheres can be added directly to the fiber mat's forming press. If the product is used in the form of a container closure or sealing member, additional fibers are added after the forming press. The material can be a fibrous material, preferably a cellulosic material, a polymeric material, or a combination thereof.

[0051] Microspheres can be added in expanded or unexpanded form, or a combination of both. Non-expanded spheres can be expanded, completely or partially, by heating during the fiber mat manufacturing process (wet or dry). Spheres can also be expanded by heat imparted to the pressing operation. Alternatively, they can be expanded before or just before the filling or closing process (see dairy manufacturing processes in which dairy products are filled into containers made essentially of cellulosic fibers and subsequently sealed).

[0052] The final product may then comprise fully or partially expanded microspheres, or alternatively, may comprise spheres that are expanded and then compressed in a pressing operation.

[0053] According to a preferred embodiment of the method described above with respect to claim 1, the expandable microspheres are thermally expandable thermoplastic microspheres or pre-expanded thermally expandable thermoplastic microspheres, or a combination thereof. The expandable thermoplastic microspheres may be fossil or biopolymer materials. Examples of such expandable microspheres include those sold by Nouryon under the name "Expancel Microspheres."

[0054] According to a preferred embodiment of the above-mentioned textile press mould, the textile press mould comprises a releasable gasket member applied to the bottom (23) of the stamp device (3), said gasket member forming an interior on top of said bottom (11) of the formed textile product (1), preferably said gasket member being at least partially elastic and compressible.

[0055] The present application also provides a textile product obtainable by the method according to claim 1 above or by the method according to any one of the preferred embodiments described above.

Claims

1. A method for pressing a textile product at high pressure and temperature using a press pad device (2) and a stamp device (3), wherein the press pad device (2) comprises a cavity (22) having a substantially horizontal bottom (23) of substantial height and substantially vertical walls (24), and the stamp device (3) comprises a substantially horizontal bottom (31) and substantially vertical walls (34), and the textile product (1) is produced from a substantially flat blank (5) with a gap formed between the bottom (23, 31) and the walls (24, 34), whereby the blank (5) has a cup shape after pressing and has a substantially flat shape.

1. A press-molding method comprising: providing the substantially vertical wall (24) of the pad device (2) at an angle (α), the angle (α) being greater than the corresponding angle (β) of the substantially vertical wall (34) of the stamp device (3) relative to the vertical, thereby forming an at least partially upwardly diverging gap and shaping the substantially vertical wall (12); and wherein the material of the textile product (1) comprises wood, natural fibers made from straw, natural fibers such as bagasse, and / or recycled fibers, or a combination thereof.

2. 2. The press-molding method according to claim 1, wherein the upper edge (10) of the textile (1) is positioned in the cavity (22) of the press pad device (2) after forming at least the bottom part (11), and preferably the entire portion of the upper edge (10) is positioned below the upper surface of the body (20) of the press pad device (2).

3. 3. The press-molding method according to claim 1, wherein the final position of the first stamp member (3) is stopped at a given distance relative to the position of the press pad device (2), so that the bottom (11) reaches a given thickness (t11).

4. 4. The press-molding method according to claim 1, wherein a pressure is applied to the top edge (10), preferably said pressure being different from the pressure acting on the bottom (11), more preferably said pressure being applied by a separate additional stamp device (4).

5. 5. The press-molding method according to any one of claims 1 to 4, wherein protrusions, preferably screws and / or gripping bars, are embossed into the textile by embossing with the press pad device (2) and / or by using the stamp device (3).

6. 6. The press-molding method according to any one of claims 1 to 5, further comprising a gasket member applied to the bottom part (23) of the stamp device (3), said gasket member forming an interior on top of said bottom part (11) after pressing.

7. 7. The press-molding method of claim 6, wherein the gasket member is at least partially resilient, preferably compressible.

8. 2. The press-molding method according to claim 1, wherein the mold temperature is about 80 to about 250°C, preferably about 150 to about 250°C, and the pressure on the bottom (11) is at least 200 bar.

9. 2. The press-molding method according to claim 1, wherein the amount of water in the material does not exceed the amount of fibers, and preferably the weight of water in the material does not exceed 20% of the weight of the fibers.

10. 2. The press-molding method of claim 1, wherein pre-expanded microspheres and / or expandable microspheres are added during the pressing or before the pressing begins, preferably the pre-expanded microspheres and / or expandable microspheres are added to the material before the pressing begins.

11. 11. The press molding method of claim 10, wherein the pre-expanded and / or expandable microspheres are processed at about 50 to about 150°C, preferably about 50 to about 120°C, and most preferably about 60 to about 100°C, thus providing a dry content of about 50 to about 70%, and thus providing an expanded or foamed product.

12. 12. The press-molding method according to claim 10 or 11, wherein steam is added during the step for expanding the material.

13. A textile product obtainable by the method according to any one of claims 1 to 12.

14. 1. A textile press mould comprising a press pad device (2) and a stamp device (3) configured to form a cup-shaped textile product (1) comprising a bottom (11) and a substantially vertical wall (12), characterized in that the substantially vertical wall (24) of the pad device (2) has an angle (α) with respect to the vertical that is greater than the corresponding angle (β) of the substantially vertical wall (34) of the stamp device (3), thereby forming an at least partially upwardly diverging gap (22) and shaping the substantially vertical wall (12).

15. 15. The textile press tool according to claim 14, further comprising an additional stamp device (4), said additional stamp device (4) preferably being independent from said first stamp member (3).

16. 16. The textile press mould according to claim 14 or 15, comprising a releasable gasket member applied to the bottom (23) of the stamp device (3), said gasket member forming an interior on top of the bottom (11) of the formed textile product (1), preferably said gasket member being at least partly elastic and compressible.

17. 1. A textile product comprising a bottom portion (11) and an edge portion (10), characterized in that the edge portion (10) has a higher density than the bottom portion (11) and / or a higher density than a portion of a side wall (12) closer to the bottom (11) than the edge portion (10).

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