阅读说明：本技术 一种具备氢爆结构的超轻鞋底制备方法、鞋底及运动鞋 (Preparation method of ultralight sole with hydrogen explosion structure, sole and sports shoe ) 是由 吴荣照 林秀欣 袁雄文 钟素丹 于 2021-09-11 设计创作，主要内容包括：本发明涉及鞋材技术领域,具体指一种具备氢爆结构的超轻鞋底制备方法、鞋底及运动鞋。该超轻鞋底制备方法中的原料包括以下质量份数的原料制成：聚氨酯预聚体60-70份,晶须3.5-7.5份,扩链剂2.5-3.5份,抗菌聚酰胺14-24份,聚硅氧烷-聚酰亚胺嵌段共聚物7-12份,成核剂1.5-2.1份,交联剂1.5-1.8份。本发明将TPU与PA进行复合,并通过超临界发泡工艺制备得到该复合材料,该复合材料主要应用在鞋底的中底中,通过在TPU中添加晶须,进一步增强其机械强度和韧度,并通过添加抗菌改性PA,使得鞋底具有一定抗菌性,其制备的运动鞋耐用性和弹性均较为优良。(The invention relates to the technical field of shoe materials, in particular to a preparation method of an ultra-light sole with a hydrogen explosion structure, the sole and a sports shoe. The preparation method of the ultralight sole comprises the following raw materials in parts by weight: 60-70 parts of polyurethane prepolymer, 3.5-7.5 parts of whisker, 2.5-3.5 parts of chain extender, 14-24 parts of antibacterial polyamide, 7-12 parts of polysiloxane-polyimide block copolymer, 1.5-2.1 parts of nucleating agent and 1.5-1.8 parts of cross-linking agent. The TPU and the PA are compounded, the composite material is prepared by a supercritical foaming process, the composite material is mainly applied to the middle sole of the sole, the mechanical strength and toughness of the TPU are further enhanced by adding the crystal whiskers into the TPU, the PA is modified by adding the antibacterial agent, the sole has a certain antibacterial property, and the prepared sports shoe has excellent durability and elasticity.)

1. A preparation method of an ultralight sole with a hydrogen explosion structure is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: weighing raw materials of a polyurethane prepolymer and whiskers, adding the whiskers into the raw materials of the polyurethane prepolymer, and forming the polyurethane prepolymer containing the whiskers under the conditions of a certain time and temperature;

step two: the polyamide slices and the antibacterial agent are uniformly mixed according to a proportion, melted and Gong mixed by a conical double-screw base machine and then extruded to form the antibacterial polyamide;

step three: mixing the polyurethane prepolymer obtained in the step one with a chain extender, and conveying the mixture into an internal mixer to be internally mixed for 60-90min at the temperature of 130-;

step four: adding the antibacterial polyamide obtained in the step two and the polysiloxane-polyimide block copolymer into an internal mixer, and continuously mixing for 20-30 min;

step five: adding a nucleating agent and a cross-linking agent into an internal mixer, and carrying out internal mixing at the temperature of 120-;

step six: adding the copolymer into an extruder, wherein the temperature of the extruder is 180-205 ℃, drying after extrusion, and pelletizing;

step seven: sending the particles obtained in the step six into an electron beam radiation chamber for radiation crosslinking;

step eight: placing the crosslinked particles into a supercritical reaction kettle, adding water and pentane into the kettle, then introducing gas fluid, starting stirring, heating, fully pressurizing for a certain time, and decompressing to obtain foamed particles;

step nine: and (3) putting the foamed particles into a mold, introducing steam for secondary molding, wherein the steam pressure is 0.15-0.4MPa, the hot-pressing time is 50-80s, the cooling time is 110-130s, and cooling to obtain the foamed insole.

2. The method for preparing an ultra-light sole with a hydrogen explosion structure according to claim 1, is characterized in that: the preparation method also comprises the following step ten: and carrying out hot-pressing bonding or adhesive bonding on the obtained insole and the shoe outsole to obtain a finished product of the sole.

3. The method for preparing an ultra-light sole with a hydrogen explosion structure according to claim 2, is characterized in that: the shoe outsole is a rubber outsole, and the specific bonding process comprises the following steps: and (3) melting the rubber of the shoe outsole, placing the rubber into an outsole mold, then placing the shoe insole on the outsole, carrying out compression molding, and cooling to room temperature to obtain a finished shoe sole.

4. The method for preparing an ultra-light sole with a hydrogen explosion structure according to claim 1, is characterized in that: the preparation raw materials of the ultralight sole comprise the following raw materials in parts by weight: 60-70 parts of polyurethane prepolymer, 3.5-7.5 parts of whisker, 2.5-3.5 parts of chain extender, 14-24 parts of antibacterial polyamide, 7-12 parts of polysiloxane-polyimide block copolymer, 1.5-2.1 parts of nucleating agent and 1.5-1.8 parts of cross-linking agent.

5. The method for preparing an ultra-light sole with a hydrogen explosion structure according to claim 4, is characterized in that: the polyurethane prepolymer is prepared from poly epsilon-caprolactone and diphenylmethane diisocyanate.

6. The method for preparing an ultra-light sole with a hydrogen explosion structure according to claim 2, is characterized in that: the whisker is CaSO4 whisker or SiC whisker.

7. The method for preparing an ultra-light sole with a hydrogen explosion structure according to claim 4, is characterized in that: the mass content of the whisker is 6-8% of that of the polyurethane prepolymer.

8. The method for preparing an ultra-light sole with a hydrogen explosion structure according to claim 2, is characterized in that: the dosage of the silane coupling agent is 0.8-1.2% of the mass of the whisker.

9. The utility model provides an ultralight sole that possesses hydrogen and explodes structure which characterized in that: the shoe sole is manufactured by the method for manufacturing the ultra-light shoe sole according to any one of claims 1 to 8.

10. An athletic shoe, characterized by: the sole of the sports shoe is the ultra-light sole with hydrogen explosion structure according to claim 9.

Technical Field

The invention relates to the technical field of shoe materials, in particular to a preparation method of an ultra-light sole with a hydrogen explosion structure, the sole and a sports shoe.

Background

The TPU is named as thermoplastic polyurethane elastomer rubber and mainly comprises polyester type and polyether type, HAs wide hardness range (60HA-85HD), wear resistance, oil resistance, transparency and good elasticity, and is widely applied to the fields of daily necessities, sports goods, toys, decorative materials and the like, and HAs the main characteristics that the hardness range is wide, products with different hardness can be obtained by changing the proportion of each reaction component of the TPU, and the products still keep good elasticity and wear resistance along with the increase of the hardness; the mechanical strength is high, and the bearing capacity, the impact resistance and the shock absorption performance of the TPU product are outstanding; the cold resistance is outstanding, the glass transition temperature of the TPU is lower, and the TPU still keeps good elasticity, flexibility and other physical properties at minus 35 ℃.

TPU foamed materials are also increasingly known as insole materials, and compared with the traditional EVA foamed soles, the TPU foamed soles have the advantages of low density, light weight, high resilience, compression resistance, compression permanence, low deformation rate and the like. However, the mechanical properties and the service performance of the TPU foaming material such as tensile strength, tearing strength and the like are still improved.

The PA is named as polyamide, and the foaming material has the advantages of high mechanical strength, good toughness, excellent tensile and compression resistance, outstanding fatigue resistance, high softening point, smooth surface, corrosion resistance and the like, but has poor rigidity, and the application of the single PA foaming material in the fields of shoe materials and the like is less.

Furthermore, with the increasing health awareness of consumers, the selection of functional materials such as comfort and antibacterial materials is becoming one of the important considerations for the selection of consumers, and especially, the selection of shoe materials is necessary to have mechanical properties, comfort and antibacterial properties.

Disclosure of Invention

In order to solve at least one of the above technical problems, a first aspect of the present invention provides a method for manufacturing an ultra-light shoe sole having a hydrogen explosion structure, including the steps of:

the method comprises the following steps: weighing raw materials of a polyurethane prepolymer and whiskers, adding the whiskers into the raw materials of the polyurethane prepolymer, and forming the polyurethane prepolymer containing the whiskers under the conditions of a certain time and temperature;

step two: the polyamide slices and the antibacterial agent are uniformly mixed according to a proportion, melted and Gong mixed by a conical double-screw base machine and then extruded to form the antibacterial polyamide;

step three: mixing the polyurethane prepolymer obtained in the step one with a chain extender, and conveying the mixture into an internal mixer to be internally mixed for 60-90min at the temperature of 130-;

step four: adding the antibacterial polyamide obtained in the step two and the polysiloxane-polyimide block copolymer into an internal mixer, and continuously mixing for 20-30 min;

step five: adding a nucleating agent and a cross-linking agent into an internal mixer, and carrying out internal mixing at the temperature of 120-;

step six: adding the copolymer into an extruder, wherein the temperature of the extruder is 180-205 ℃, drying after extrusion, and pelletizing;

step seven: sending the particles obtained in the step six into an electron beam radiation chamber for radiation crosslinking;

step eight: placing the crosslinked particles into a supercritical reaction kettle, adding water and pentane into the kettle, then introducing gas fluid, starting stirring, heating, fully pressurizing for a certain time, and decompressing to obtain foamed particles;

step nine: and (3) putting the foamed particles into a mold, introducing steam for secondary molding, wherein the steam pressure is 0.15-0.4MPa, the hot-pressing time is 50-80s, the cooling time is 110-130s, and cooling to obtain the foamed insole.

As a preferable embodiment of the present invention, the preparation method further includes the step ten: and carrying out hot-pressing bonding or adhesive bonding on the obtained insole and the shoe outsole to obtain a finished product of the sole.

As a preferred scheme of the invention, the shoe outsole is a rubber outsole, and the specific bonding process of the shoe outsole is as follows: and (3) melting the rubber of the shoe outsole, placing the rubber into an outsole mold, then placing the shoe insole on the outsole, carrying out compression molding, and cooling to room temperature to obtain a finished shoe sole.

As a preferred scheme of the invention, the shoe outsole is a rubber outsole, and the specific bonding process of the shoe outsole is as follows: and (3) melting the rubber of the outsole of the shoe, placing the rubber into an outsole mold for compression molding, then coating a chemical adhesive on the upper surface of the molded outsole, placing the insole of the shoe on the outsole, carrying out hot pressing, and cooling to room temperature to obtain a finished sole.

As a preferred scheme of the invention, the preparation raw materials of the ultralight sole comprise the following raw materials in parts by weight: 60-70 parts of polyurethane prepolymer, 3.5-7.5 parts of whisker, 2.5-3.5 parts of chain extender, 14-24 parts of antibacterial polyamide, 7-12 parts of polysiloxane-polyimide block copolymer, 1.5-2.1 parts of nucleating agent and 1.5-1.8 parts of cross-linking agent.

As a preferable scheme of the invention, the polyurethane prepolymer is prepared from poly epsilon-caprolactone and diphenylmethane diisocyanate.

In a preferred embodiment of the present invention, the whisker is a CaSO4 whisker or a SiC whisker.

As a preferable scheme of the invention, the mass content of the whiskers is 6-8% of that of the polyurethane prepolymer.

In a preferable embodiment of the present invention, the amount of the silane coupling agent is 0.8% to 1.2% by mass of the whisker.

As a preferred scheme of the invention, the whisker is pretreated, and the pretreatment process comprises the following steps: preparing 10% KH-550 acetone solution, mixing with vacuum dried CaSO4 crystal whisker, adding silane coupling agent, taking out, and drying at 75-85 deg.C for 1.5-2.5 h.

As a preferable scheme of the invention, the banburying temperature in the third step is 140 ℃ and the banburying time is 80 min.

In a preferred embodiment of the present invention, the banburying time in the fourth step is 25 min.

In a preferred embodiment of the present invention, the temperature of the extruder in the sixth step is 185 ℃.

As a preferable embodiment of the present invention, the gaseous fluid in step eight is CO2 and/or N2.

In a preferred embodiment of the present invention, the saturation time in step eight is 0.5 to 4 hours.

In a preferred embodiment of the present invention, the antibacterial agent in the antibacterial polyamide is a chitosan-silver/titanium dioxide (CA/T) composite antibacterial agent.

In a preferred embodiment of the present invention, the antibacterial agent in the antibacterial polyamide is betaine sulfate.

As a second aspect of the present invention, an ultra-light shoe sole with a hydrogen explosion structure is provided, which is prepared by the above-mentioned method for preparing an ultra-light shoe sole.

In a preferred embodiment of the present invention, the sole includes a midsole and an outsole, the midsole includes midsole lateral sides and a midsole bottom, wherein the midsole lateral sides are wavy and have a height greater than the midsole bottom.

As a preferable scheme of the present invention, a hollow structure is disposed in a region of the midsole corresponding to the heel of the human body, an elastic air bag is disposed in the hollow structure, and the elastic air bag is filled with the foamed particles prepared by the above preparation method.

As a preferable scheme of the invention, the upper surface of the outsole is provided with a plurality of concentric geometric grooves, the lower surface of the midsole is provided with a plurality of geometric bulges matched with the shapes of the concentric geometric grooves, and when the outsole is connected with the midsole, the geometric bulges are embedded into the concentric geometric grooves to enhance the connection fastness of the outsole and the midsole.

As a third aspect of the present invention, there is provided a sports shoe having a sole that is an ultra-light sole having the hydrogen explosion structure as described above.

Compared with the prior art, the invention has the beneficial effects that:

the TPU and the polyamide PA are compounded, and the composite material is prepared by a supercritical foaming process, and the composite material is mainly applied to the middle sole of a sole, and the mechanical strength and toughness of the composite material are further enhanced by adding whiskers into the TPU.

2, the polyamide PA material after antibacterial treatment is adopted, so that the obtained composite material has certain antibacterial property, when the composite material is applied to the shoe insole, the shoe sole has certain antibacterial property, the limitation that only the vamp or the insole is subjected to antibacterial treatment in the field of traditional shoe materials is broken, and the sole with the antibacterial effect is researched initiatively.

The 3 polyamide PA material has higher mechanical strength, is compounded with the TPU material, can enhance the mechanical strength of the TPU material, can adjust the addition amount of the polyamide PA according to the requirement, can properly improve the content of the polyamide PA when the shoe midsole with higher mechanical strength is required, and can reduce the addition amount of the PA to obtain the shoe midsole with higher softness.

4, the upper surface of the rubber outsole is connected with the lower surface of the midsole through the embedding of the concentric geometric grooves and the geometric bulges, so that the connection fastness of the rubber outsole and the midsole is enhanced.

5 the region of the insole corresponding to the heel of the human body is provided with the elastic air bag, so that the elasticity of the heel part can be enhanced, the wearing comfort level is improved, and the function of elastic assistance is achieved.

Drawings

FIG. 1 is a schematic flow chart of a method for manufacturing an ultralight shoe sole with a hydrogen explosion structure according to an embodiment of the invention;

FIG. 2 is a schematic view showing the overall structure of a midsole of an ultra light sole having a hydrogen explosion structure according to an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view illustrating a midsole of an ultra light sole having a hydrogen explosion structure according to an embodiment of the present invention;

FIG. 4 is a schematic structural view of a midsole and an outsole of an ultra light shoe sole having a hydrogen explosion structure according to an embodiment of the present invention;

fig. 5 is a schematic structural view of an athletic shoe having an ultra-light sole with a hydrogen explosion structure according to an embodiment of the present invention.

The novel shoe sole comprises a midsole 1, geometric bulges 10, a midsole side wall 11, a midsole bottom surface 13, an elastic air bag 12, an outsole 2 and concentric geometric grooves 20.

Detailed Description

[ first embodiment according to the present invention ]

The invention provides a supercritical TPU composite material as a first implementation mode, which is prepared from the following raw materials in parts by mass: 60-70 parts of polyurethane prepolymer, 3.5-7.5 parts of whisker, 2.5-3.5 parts of chain extender, 14-24 parts of antibacterial polyamide, 7-12 parts of polysiloxane-polyimide block copolymer, 1.5-2.1 parts of nucleating agent and 1.5-1.8 parts of cross-linking agent. Specifically, the mass content of the whisker is 6-8% of that of the polyurethane prepolymer.

Example 1 according to the first embodiment of the present invention

A supercritical TPU composite material is prepared from the following raw materials in parts by mass: 68.0 parts of polyurethane prepolymer, 4.0 parts of whisker, 2.6 parts of chain extender, 15.0 parts of antibacterial polyamide, 7.0 parts of polysiloxane-polyimide block copolymer, 1.8 parts of nucleating agent and 1.6 parts of cross-linking agent. The polyurethane prepolymer can be prepared from poly-epsilon-caprolactone and diphenylmethane diisocyanate, the average molar mass of the poly-epsilon-caprolactone is 2300, (R (NCO/OH) in the formed polyurethane elastomer is 3; the nucleating agent can be a mixture of TMC-328 nucleating agent and zinc acrylate, the chain extender can be 4-hydroxyethyl oxyethyl-1-hydroxyethyl benzene diether, and the crosslinking agent is an isocyanate crosslinking agent).

In this example, the whisker is CaSO4 whisker, the antibacterial polyamide is antibacterial PA6, and the antibacterial agent used in the antibacterial polyamide is a chitosan-silver/titanium dioxide (CA/T) composite antibacterial agent.

Example 2 according to the first embodiment of the present invention

A supercritical TPU composite material is prepared from the following raw materials in parts by mass: 62.0 parts of polyurethane prepolymer, 4.5 parts of whisker, 2.4 parts of chain extender, 18.2 parts of antibacterial polyamide, 9.3 parts of polysiloxane-polyimide block copolymer, 1.9 parts of nucleating agent and 1.7 parts of cross-linking agent. The polyurethane prepolymer can be prepared from poly-epsilon-caprolactone and diphenylmethane diisocyanate, the average molar mass of the poly-epsilon-caprolactone is 1993, and R (NCO/OH) in a formed polyurethane elastomer is 10; the nucleating agent can be sorbitol nucleating agent, the chain extender can be hydroquinone di- (beta-hydroxyethyl) ether, and the cross-linking agent is isocyanate cross-linking agent.

In this example, the whisker is SiC whisker, the antibacterial polyamide is antibacterial PA66, and the antibacterial agent used in the antibacterial polyamide is betaine sulfate.

[ second embodiment according to the present invention ]

As a second embodiment of the present invention, the present invention provides a method for preparing a supercritical TPU composite material, comprising the steps of:

the method comprises the following steps: weighing raw materials of a polyurethane prepolymer and whiskers, adding the whiskers into the raw materials of the polyurethane prepolymer, and forming the polyurethane prepolymer containing the whiskers under the conditions of a certain time and temperature;

step two: the polyamide slices and the antibacterial agent are uniformly mixed according to a proportion, melted and Gong mixed by a conical double-screw base machine and then extruded to form the antibacterial polyamide;

step three: mixing the polyurethane prepolymer obtained in the step one with a chain extender, and conveying the mixture into an internal mixer to be internally mixed for 60-90min at the temperature of 130-;

step four: adding the antibacterial polyamide obtained in the step two and the polysiloxane-polyimide block copolymer into an internal mixer, and continuously mixing for 20-30 min;

step five: adding a nucleating agent and a cross-linking agent into an internal mixer, and carrying out internal mixing at the temperature of 120-;

step six: adding the copolymer into an extruder, wherein the temperature of the extruder is 180-205 ℃, drying after extrusion, and pelletizing;

step seven: sending the particles obtained in the step six into an electron beam radiation chamber for radiation crosslinking;

step eight: and (3) placing the crosslinked particles into a supercritical reaction kettle, adding water and pentane into the kettle, then introducing gas fluid, starting stirring, heating, fully pressurizing for a certain time, and decompressing to obtain the foamed particles.

As a preferred scheme of the invention, the whisker is pretreated, and the pretreatment process comprises the following steps: preparing 10% KH-550 acetone solution, mixing with vacuum dried CaSO4 whisker, adding silane coupling agent, taking out, and drying at 75-85 deg.C for 1.5-2.5h, wherein in the embodiment, the silane coupling agent can be commercially available type HK550, HK560 or HK 570.

Specifically, the amount of the silane coupling agent is 0.8% to 1.2% by mass of the whisker, and may be, for example, 1.0%.

Specifically, the banburying temperature in the third step is 140 ℃, and the banburying time is 80 min.

Specifically, the banburying time in the fourth step is 25 min.

Specifically, the extruder temperature in the sixth step is 185 ℃.

Specifically, the gaseous fluid CO2 and/or N2 in the step eight.

Specifically, the pressure saturation time in the step eight is 0.5 to 4 hours.

[ third embodiment according to the present invention ]

As a third embodiment of the present invention, the present invention provides an ultra-light sole with hydrogen explosion structure, which is made of the above-mentioned supercritical TPU composite material, and the sole comprises a midsole 1 and an outsole 2, wherein the midsole 1 is made of the above-mentioned TPU composite material, and structurally, as shown in fig. 2 and 3, in order to increase the stability of the upper, the bottom side upper 11 is in a wave shape, and the height of the midsole side upper 11 is higher than the height of the midsole bottom 13, so as to increase the support of the sides of the upper.

As another embodiment of the present invention, as shown in FIGS. 2 and 3, the heel of the midsole 1 has a hollow structure, wherein the hollow structure is connected with an elastic bladder 12, and the TPU composite particles are distributed in the elastic bladder 12. The arrangement of the elastic air bag 12 can increase the elasticity of the heel of the sole.

As shown in fig. 5, the present invention further provides a sports shoe, the sole of the sports shoe adopts the sole as described above, preferably, the wave shape is a wave shape, wherein the wave crest portions correspond to two sides of the heel, the arch and the toe portion, the wave trough portions correspond to two sides of the sole portion, the arrangement of the wave crest portions can increase the contact area when the midsole and the upper are adhered, increase the adhesion fastness, and the wave trough portions prevent the sole bending resistance caused by the too high midsole side 11 on the two sides of the sole portion, so that the sole is more comfortable.

In order to increase the connection fastness between the outsole and the midsole, as shown in fig. 4, the outsole 2 of the sole is made of a rubber layer with excellent anti-slip performance, wherein the upper surface of the outsole is provided with a plurality of concentric geometric grooves 20, the lower surface of the midsole 1 is provided with a plurality of geometric protrusions 10 matched with the concentric geometric grooves 20 of the outsole, the outsole 2 is bonded with the midsole 1 or connected by hot pressing, the concentric geometric grooves 20 and the geometric protrusions 10 are embedded into each other, so that the contact area and the bonding fastness between the outsole 2 and the midsole 1 can be increased, the shape of the concentric geometric grooves 20 can be regular geometric shapes, such as circular, triangular, rectangular, pentagonal, hexagonal, oval and the like, and can also be irregular shapes, and the shapes can be set arbitrarily according to needs.

[ fourth embodiment according to the present invention ]

As a fourth embodiment of the present invention, the present invention provides a preparation method of an ultralight shoe sole with a hydrogen explosion structure, as shown in fig. 1, the preparation method is based on the preparation method of the supercritical TPU composite material, after obtaining the foamed particles, putting the foamed particles into a mold, introducing steam for secondary molding, wherein the steam pressure is 0.15-0.4MPa, the hot pressing time is 50-80s, and the cooling time is 110-130s, and cooling to obtain a finished foamed shoe midsole product. And carrying out hot-pressing bonding or adhesive bonding on the obtained insole and the shoe outsole to obtain a finished product of the sole.

Example 1 according to embodiment four of the present invention

In this embodiment, after obtaining the foamed particles, the foamed particles are placed in a mold and steam is introduced to perform secondary molding, the steam pressure is 0.3MPa, the hot pressing time is 60s, the cooling time is 120s, and a foamed insole finished product is obtained after cooling.

Example 2 according to embodiment four of the present invention

In this embodiment, after obtaining the foamed particles, the foamed particles are placed in a mold and steam is introduced to perform secondary molding, the steam pressure is 0.25MPa, the hot pressing time is 75s, the cooling time is 115s, and a foamed insole finished product is obtained after cooling.

Carrying out hot-pressing bonding or adhesive bonding on the obtained insole and the shoe outsole to obtain a finished sole, wherein the bonding process can be as follows: the shoe outsole is a rubber outsole, and the specific bonding process comprises the following steps: and (3) melting the rubber of the shoe outsole, placing the rubber into an outsole mold, then placing the shoe insole on the outsole, carrying out compression molding, and cooling to room temperature to obtain a finished shoe sole.

In addition, the bonding process of the insole and the outsole can also be as follows: and (3) melting the rubber of the outsole of the shoe, placing the rubber into an outsole mold for compression molding, then coating a chemical adhesive on the upper surface of the molded outsole, placing the insole of the shoe on the outsole, carrying out hot pressing, and cooling to room temperature to obtain a finished sole.

While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.