Patent Application
20170127761
The present invention relates to a composite laminated structure for shoe stiffeners and the preparing methods thereof. More particularly, the present invention relates to a composite laminated structure using fabrics as its core.
In shoe industry, stiffeners are usually used in the toe part or the heel part, known as toe puffs and counters, respectively. The use of stiffeners is aimed at providing support to shoe upper materials. Thus, materials for toe puffs and counters usually require proper split tear strength and resilience. Split tear strength is defined to represent the desired durability of shoe uppers, while resilience is defined to represent the recovery of the original shape upon deformation for any factors.
There are various stiffeners used in shoe industry, including: impregnated stiffeners, premolded stiffeners, powder coated stiffeners, extruded stiffeners, or the like. Here, impregnated stiffeners can be made stiff, but the ones with high stiffness usually do not have high resilience and operability under low temperature or long time. Impregnated stiffeners, premolded stiffeners and extruded stiffeners all require expensive processing steps. For example, extruded stiffeners are made via extrusion of resins such as ionomers or other thermoplastic polymers, followed by extrusion coating of binders onto polymer sheets, so that the desired resilience and split tear strength can be achieved. Such a process leads to increased processing steps and cost. Furthermore, it takes long time if not forever for these materials to be decomposed. Lots of waste is generated accordingly. To improve, there is a strong need for cheaper, better, and environmentally friendly stiffeners, which provide good split tear strength, resilience, and bending stiffness while using less virgin plastic materials.
In light of the deficiencies in prior art, a composite laminated structure for a shoe stiffener is provided herein, comprising:
a fabric core layer;
a hot-melt-adhesive layer, covering and interpenetrating the fabric core layer;
wherein the fabric core layer comprises a fabric having a fabric count of about 61 to 13 warp yarns per inch (wpi) and about 60 to 30 filling yarns per inch (fpi) and a weight more than or equal to 100 g/m2.
A permanent interlocking structure will be formed among the fibers in the fabric core layer via interpenetration of the hot-melt-adhesive layer into the fabric core layer, and thus, the composite laminated structure will have excellent split tear strength and resilience.
In one embodiment, the composite laminated structure without a filler may have a split tear strength greater than or equal to 87.5 kgf/cm.
In another embodiment, the composite laminated structure may have a resilience greater than or equal to 5.0 kgf.
In one embodiment, the fabric core layer may have a bending stiffness greater than 2000 mg·cm. In one preferred embodiment, the fabric core layer may have a bending stiffness of about 2000 to about 25000 mg·cm.
In another embodiment, the bending stiffness for the fabric core layer can be determined by using standard ISO 9073 and GB 18318 test methods but not limited hereto.
In a specific embodiment, the fabric core layer may comprise, but is not limited to, fine cloth for cap interlining and cloth (40 (wpi)×40 (fpi)) for cap interlining, or the like.
In one embodiment, the hot-melt-adhesive layer may be a low application temperature hot-melt-adhesive layer having a softening temperature lower than 90° C. and a solidification time greater than one minute. In a specific embodiment, the low application temperature hot-melt-adhesive layer may comprise, but is not limited to, thermoplastic polyurethane (TPU), polycaprolactone (CAPA), or the like.
In one embodiment, the composite laminated structure may further comprise at least an adhesive layer to enhance its adhesion, such that the composite laminated structure can be connected to an upper or a lining and better laminated to more inert materials, e.g. greasy leathers.
In one embodiment, the composite laminated structure may further comprise a filler. And the percentage of the filler in the hot-melt-adhesive layer may be up to 90%. In another embodiment, the percentage of the filler in the hot-melt-adhesive layer may be up to 80%.
In a specific embodiment, the filler may comprise, but is not limited to, an inorganic filler material, such as inorganic mineral powders (e.g. calcium carbonate powders, silica powders, or the like); an organic polymer material, such as recycled plastic materials; or a combination thereof. One skilled in the art can optionally select the filler material as needed.
In a specific embodiment, the recycled plastic material may comprise, but is not limited to, polycarbonate (PC), thermoplastic polyurethane (TPU), polyethylene terephthalate (PET), phenol-formaldehyde resin, urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin, unsaturated polyester resin, polyurethane, a mixture thereof, or the like.
A method for preparing the composite laminated structure is also provided herein, including steps of:
providing a first hot-melt-adhesive material in a molten state;
providing a fabric, wherein the fabric is placed onto the first hot-melt-adhesive material in the molten state;
providing a second hot-melt-adhesive material in a molten state, wherein the second hot-melt-adhesive material in the molten state is placed onto the fabric; and
co-extruding and laminating the first hot-melt-adhesive material in the molten state, the fabric and the second hot-melt-adhesive material in the molten state to form the composite laminated structure.
The present invention further provides a method for preparing the composite laminated structure, including steps of:
providing a first hot-melt-adhesive material in a preheated mold;
providing a fabric, wherein the fabric is placed onto the first hot-melt-adhesive material;
providing a second hot-melt-adhesive material, wherein the second hot-melt-adhesive material is placed onto the fabric;
forming the first hot melt adhesive material and the second hot melt adhesive material to be in a molten state in the mold, and pressing the first hot melt adhesive material in the molten state, the second hot melt adhesive material in the molten state and the fabric together to form the composite laminated structure.
In one embodiment, the first hot-melt-adhesive material and the second hot-melt-adhesive material may be the same. Optionally, in another embodiment, the first hot-melt-adhesive material and the second hot-melt-adhesive material may be different.
In one embodiment, the method for preparing the composite laminated structure may further comprise a step of coating an adhesive layer onto a surface of the composite laminated structure.
The present invention provides another method for preparing the composite laminated structure, including steps of:
providing a hot-melt-adhesive material in a molten state;
providing a fabric, wherein the fabric is placed onto the hot-melt-adhesive material in the molten state; and
extruding and laminating the hot melt adhesive material in the molten state and the fabric to form the composite laminated structure.
The present invention provides still another method for preparing the composite laminated structure, including steps of:
providing a hot-melt-adhesive material in a preheated mold;
providing a fabric, wherein the fabric is placed onto the hot-melt-adhesive material;
forming the hot melt adhesive material to be in the molten state in the mold, and pressing the hot melt adhesive material in the molten state and the fabric together to form the composite laminated structure.
In one embodiment, the method for preparing the composite laminated structure may further comprise a step of coating an adhesive layer onto a surface of the composite laminated structure.
The present invention further provides a composite laminated structure for a shoe stiffener, comprising:
a fabric core layer;
a first hot-melt-adhesive layer and a second hot-melt-adhesive layer, which cover opposite surfaces of the fabric core layer and interpenetrate the fabric core layer;
wherein the fabric core layer comprises a fabric having a fabric count of about 61 to 13 warp yarns per inch (wpi) and about 60 to 30 filling yarns per inch (fpi) and a weight more than or equal to 100 g/m2.
Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Other objectives, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
In this example, the first hot-melt-adhesive layer 11 and the second hot-melt-adhesive layer 13 are low application temperature hot-melt-adhesive layers of TPU, having a softening temperature lower than 90° C. and a solidification time greater than one minute. The first hot-melt-adhesive layer 11 and the second hot-melt-adhesive layer 13 may optionally comprise a filler of up to 90% or 80%, such as an inorganic filler material, an organic polymer material or the like. One skilled in the art may optionally select the filler material as needed. In this example, the organic polymer material used is a recycled plastic material, comprising, but not limited to, polycarbonate (PC), thermoplastic polyurethane (TPU), polyethylene terephthalate (PET), phenol-formaldehyde resin, urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin, unsaturated polyester resin, polyurethane or a mixture thereof.
The above-mentioned fabric core layer 12 may be made of a fabric having a fabric count of about 61 to 13 warp yarns per inch (wpi) and about 60 to 30 filling yarns per inch (fpi) and a weight more than or equal to 100 g/m2, for instance, fine cloth for cap interlining, cloth (40 (wpi)×40 (fpi)) for cap interlining, or the like, and its characteristics will be detailed with the tests described below.
In addition, the composite laminated structure 1 as in Example 1 may optionally comprise two adhesive layers 14, which are provided onto the surfaces of the first hot-melt-adhesive layer 11 and the second hot-melt-adhesive layer 13 respectively, to enhance its adhesion, such that the composite laminated structure 1 can be adhered to an upper or a lining and better laminated to more inert materials, e.g. greasy leathers.
The above-mentioned composite laminated structure 1 may be prepared via extrusion molding, but is not limited to this method. Any suitable plastic processing method may be used as well. In the present example, the composite laminated structure 1 is prepared via a co-extrusion/lamination process. Particularly, the hot-melt-adhesive materials and the optional recycled plastic material are added into the extruders, where the hot-melt-adhesive material is melted to a molten state. The co-extrusion process is followed by lamination of the hot-melt-adhesive material onto the fabric to form the composite laminated structure 1. After the composite laminated structure 1 is cooled and solidified, it is cut to the desired shape and size.
The above-mentioned composite laminated structure 1a may be prepared via a molding process, but is not limited to this method. In this example where a molding process was adopted, the mold had a upper die and a corresponding lower die (not shown), and part of the hot-melt-adhesive material was flattened in the mold cavity of the lower die of the preheated mold. The fabric is then placed onto the hot-melt-adhesive material in the mold. Next, the remainder of the hot-melt-adhesive material is placed onto the fabric and flattened in the mold. Then, the upper die is placed on top and followed by heating and pressing. After the process is done by a hand press, the upper die was removed. Then, the molded products are taken out after they are cooled and solidified. By the molding process, different mold shapes can be designed depending on users' needs. That is, the product may be molded into the final shape without additional cutting, and thus the waste from cutting the product into a specific shape can be reduced and the manufacturing cost may be reduced.
The samples of the fabric core layer 12, 12a are fine cloth for cap interlining, cloth for cap interlining 40 (wpi)×40 (fpi) and oxford. These samples are cut to strips of 2 cm×20 cm, held onto a clamp of a fully automatic fabric stiffness tester (Model YG022D, Wenzhou Jigao Testing Instrument Co. Ltd) and moved forward in the rate according to the operational manual of the tester. The tests are conducted by the test methods of ISO 9073 and GB 18318. When each sample passed through a bending angle, the bending stiffness (mg·cm) is automatically calculated. These data are shown in the following Table 1.
It is noteworthy that the bending stiffnesses of the spandex fabric sold under the trademark Lycra® and muslin are lower than the detection limit of the tester, thus the bending stiffnesses of the spandex fabric sold under the trademark Lycra® and muslin are shown as <500 mg·cm, which is the detection limit of the tester.
1. Process of Manufacturing the Composite Laminated Structure for a Shoe Stiffener without Recycled Plastics
A mold having an upper die and a lower die is placed on an electric hot plate and heated to 100° C. Part of the TPU hot-melt-adhesive powder was positioned in the mold cavity of the lower die, and then scraped flatly back and forth with a scraper. After the TPU powder is scraped evenly, samples of the fabric core layer are cut into smaller pieces (i.e. a fringe 111a of each sample was tapered-off) and positioned at a proper position in the mold cavity. Furthermore, the TPU powder is added evenly onto the fabric core layer in the mold cavity and scraped flatly again. A release paper is put in after the TPU powder became flat, followed by covering the upper die on top. At the time, the TPU powder is in a molten state and flattened by a hand press. After the pressing is done, the upper die and the release paper were removed. Each product is taken out after sufficient cooling.
2. Tests for Strength of Split Tear Strength
The above-mentioned composite laminated structures are cut to strips of 2 cm (width)×8 cm (length) with a thickness of 0.12 cm. Each of the strips is further cut at the middle to form a slit of 1.5 cm, and is then fixed between the upper retaining clamp and the lower retaining clamp of a universal tensile testing machine (SATRA TM65, at a rate of 100 mm/min). The maximum value measured by the machine is recorded as the strength of split tear strength. The test results are shown in Table 2.
3. Tests for Collapse Force and Compression Resilience
A pneumatic cylinder having a diameter of 16 mm is stood upright and comprises a gas pressure regulator having a ball head of 10 mm at the front. For making samples of proper size and shape, an outer frame having a diameter of 60 mm and a hemispherical fixture having an upper die and a lower die with a diameter of 47 mm and a height of 9.5 mm are prepared. Each sample of the composite laminated structure is cut into a 70 mm-diameter circle, which is further softened in hot water and shaped into a hemisphere by the hemispherical fixture. The hemispherical sample is placed under the pneumatic cylinder. The ball head at the front of the pneumatic cylinder is pointed at the central convex point of the hemispherical sample at a distance about 1 cm to start the tests.
The gas pressure regulator is set to zero, and then adjusted with visual observation of the value on the gas pressure regulator. When the ball head of the pneumatic cylinder collapses the hemispherical sample, the maximum value is recorded as the collapse pressure or collapse force. The rebound height is also measured, wherein the ratio of the rebound height to the initial height represented the shape retention. The experiment is repeated ten times. The ratio of the final to the initial pressure/force represents the resilience. The test results are shown in Table 2.
As shown in the table above, better split tear strength and collapse force could be achieved depending on the fabric used. Particularly, the composite laminated structures comprising the fabric core layers having a fabric count of about 61 to 13 wpi and about 60 to 30 fpi and a weight more than or equal to 100 g/m2, such as fine cloth for cap interlining and cloth for cap interlining 40×40 (wpi×fpi), are provided with higher split tear strength and resistant to the collapse, i.e. requiring more force to collapse the laminate structure, by the ball head of the pneumatic cylinder. Namely, with the fabric core layers having a fabric count of about 61 to 13 wpi and about 60 to 30 fpi and a weight more than 100 g/m2, for example, No. 2 and 3 in Table 2, the strength of the composite laminated structures is stronger comparing to No. 1 and 4-6 for that more force is needed to collapse the composite laminated structure.
In fact, the present application provides a composite laminate structure to keep shoes in good shape by preventing toe and counter from collapse under pressure. If the toe and counter collapse, they need to bounce back to the original shape to maintain their function, which is shown in the tests of the force for collapses and the resilience for the dome in the Tests for compression resilience described above.
Those effects may be due to the formation of interlocking structures in the fabric core layers via the interpenetration of the hot-melt-adhesive through the fabric core layer having a fabric count of about 61 to 13 wpi and about 60 to 30 fpi and a weight more than or equal to 100 g/m2. The production method for the composite laminated structures is simple, and thus the cost for shoe stiffeners could be lowered. Materials for the fabric core layer are cheap and readily available. With different fabric, one can achieve different split tear strength, collapse force and resilience. Furthermore, in the preferred examples as provided herein, the cutting step is no longer needed since the stiffeners were prepared via molding. Wastes generated from cutting the stiffeners to a specific shape could be greatly reduced.
1. Process of Manufacturing the Composite Laminated Structure for a Shoe Stiffener with Recycled Plastics
Recycled plastics are grounded into particles of about 30 to about 50 meshes in size. The hot-melt-adhesive (i.e. TPU powder) and the recycled plastic powder are weighed respectively according to the ratio shown in the following Table 3. The weighed powders are put into plastic bags, and then shaken for well mixing. A mold having an upper die and a lower die is placed onto an electric hot plate and heated to 100° C. Part of the TPU powder and the recycled plastic powder are positioned in the mold cavity of the lower die and then flattened back and forth with a scraper. After the mixture powder is scraped evenly, samples of the fabric core layer are cut to smaller pieces (i.e. a fringe 111a of each sample was tapered-off) and positioned on top. The remainder of the mixture powder is added evenly onto the fabric core layer and scraped flat again. A release paper is put in after the mixture powder became flat, followed by covering the upper die on top. At the time, the mixture powder is in a molten state and is then flattened by a hand press. After the pressing was done, the upper die and the release paper are removed. Each product is then taken out after cooled down. Tests for split tear strength and resilience are conducted respectively according to the above-mentioned method, which is not repeated here. The test results are shown in Table 3.
As shown in the above table, the composite laminated structures with the fabric core layer having a fabric count of about 61 to 13 wpi and about 60 to 30 fpi and a weight more than or equal to 100 g/m2, for example No. 1-2, 4-5, 7-8 and 10-13 in Table 3, have a significantly better split tear strength and resilience as compared to those without fabric core layer (see data for No. 3 and 6 of Table 3) or those with nonwoven as the fabric core layer (see data for No. 9 and 14 of Table 3). The composite laminated structures are environmentally friendly since the virgin material usage could be drastically reduced. The examples indicate that the desired split tear strength and resilience could be obtained by a simple process without the need of complicated treatments. The cost for shoe stiffeners could be lowered as well. In addition, in the preferred examples as provided herein, the cutting step is no longer needed since the stiffeners were prepared via molding. Wastes generated from cutting the stiffeners to specific shapes could be greatly reduced.
The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102105063 | Feb 2013 | TW | national |
This application is a continuation-in-part of U.S. patent application Ser. No. 14/024,762, filed on Sep. 12, 2013, which claims foreign priority to Taiwan Patent Application No. 102105063, filed on Feb. 8, 2013. All of the above-referenced applications are hereby incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14024762 | Sep 2013 | US |
| Child | 15415449 | US |
