阅读说明：本技术 一种超纤合成革及其制备方法 (Microfiber synthetic leather and preparation method thereof ) 是由 郑重 刘爱明 罗志清 梁勇劲 刘格 于 2019-11-01 设计创作，主要内容包括：本发明公开了一种超纤合成革,包括基布、海岛纤维和聚氨酯,所述海岛纤维和聚氨酯紧密连接在基布中,且海岛纤维和聚氨酯之间紧密连接在一起,所述海岛纤维的三维相互交联在一起形成真皮胶原纤维结构,所述聚氨酯分布在海岛纤维的四周,所述聚氨酯在海岛纤维形成的骨架中为圆形的发泡结构,所述基布、海岛纤维和聚氨酯整体呈立体网状。本发明还公开了其制备方法。本发明通过同步改进产品原材料及工艺设计,以降低制造成本和提高产品综合性能,使革体具有良好的透气以及透湿性能,而且经过干法贴面和表面处理工序,使合成革表面的耐磨性能好、附着力强,具有优良的抗磨损效果。(The invention discloses microfiber synthetic leather which comprises base cloth, sea-island fibers and polyurethane, wherein the sea-island fibers and the polyurethane are tightly connected in the base cloth, the sea-island fibers and the polyurethane are tightly connected together, the three dimensions of the sea-island fibers are mutually crosslinked to form a dermis collagen fiber structure, the polyurethane is distributed around the sea-island fibers, the polyurethane is in a circular foaming structure in a framework formed by the sea-island fibers, and the base cloth, the sea-island fibers and the polyurethane are integrally in a three-dimensional net shape. The invention also discloses a preparation method of the composition. The invention reduces the manufacturing cost and improves the comprehensive performance of the product by synchronously improving the raw materials and the process design of the product, so that the leather body has good air permeability and moisture permeability, and the surface of the synthetic leather has good wear resistance, strong adhesive force and excellent wear resistance effect through the dry facing and surface treatment procedures.)

1. A microfiber synthetic leather comprises a base cloth (1), sea-island fibers (2) and polyurethane (3), and is characterized in that: the base cloth is characterized in that the sea-island fibers (1) and the polyurethane (2) are tightly connected in the base cloth (1), the sea-island fibers (1) and the polyurethane (2) are tightly connected together, the three dimensions of the sea-island fibers (1) are mutually crosslinked to form a dermis collagen fiber structure, the polyurethane (2) is distributed around the sea-island fibers (1), the polyurethane (2) is in a circular foaming structure in a framework formed by the sea-island fibers (1), and the base cloth (1), the sea-island fibers (2) and the polyurethane (3) are integrally in a three-dimensional net shape.

2. The microfiber synthetic leather of claim 1, wherein: the skeleton formed by the polyurethane (2) on the sea-island fiber (1) is a needle-shaped foaming structure.

3. The preparation method of the microfiber synthetic leather is characterized by comprising the following steps:

firstly, preparing sea-island fibers;

secondly, post-spinning the sea-island fiber: bundling, drafting and oil-dipping, curling, heat setting, cutting and packaging, wherein 4 continuous processes, namely primary drafting, secondary drafting, tertiary drafting and curling, are adopted in the process from drafting to curling;

step three, weaving the non-woven fabric, namely weaving the post-spun sea-island fibers together to form a base fabric;

step four, wet impregnation: preparing polyurethane slurry in a soaking tank, then sending the base cloth, entering the soaking tank through a cloth storage rack, squeezing water in the base cloth by using a squeezing roller, ironing the base cloth by using an ironing wheel to be half-dried, ironing the base cloth at the same time, coating the matched slurry on a coating machine, entering a coagulating tank to form a membrane, fully washing, drying and shaping to obtain the microfiber synthetic leather;

step five, alkali decrement: dissolving sodium hydroxide, a cation accelerator and a carrier for dyeing the polyester disperse dye in water to prepare an alkali liquor, and putting the microfiber synthetic leather obtained in the fourth step into the alkali liquor, wherein the alkali decrement bath ratio is 1: 5-100 ℃, heating to 60-80 ℃ at a heating rate of 5 ℃/min, preserving heat for 60-120 min, taking out the base fabric after heat preservation is finished, washing for 3-8 times, and drying at 70-85 ℃;

step six, splitting the skin:

firstly, splitting the microfiber synthetic leather on a splitting machine, wherein the speed of the splitting machine is 3-6 m/min, and the rotating speed of a blade of the splitting machine is 1000-1500 rpm, so that the split microfiber synthetic leather is obtained.

4. The preparation method of microfiber synthetic leather according to claim 3, wherein: it also includes the following steps:

step six, buffing:

secondly, grinding the bottom of the microfiber synthetic leather on a leather grinding machine by taking the top of the microfiber synthetic leather as a reference surface, wherein the number of sand meshes of the leather grinding machine is 150-240 meshes, the rotating speed of the sand is 1000-1300 rpm, the vehicle speed is 3-5 m/min, and the leather grinding thickness is 0.03-0.08 mm; then, taking the bottom of the microfiber synthetic leather as a reference surface, and grinding the top of the microfiber synthetic leather to obtain a ground leather with the number of sand meshes of 240-480 meshes, the rotating speed of the ground leather of 1000-1300 rpm, the vehicle speed of 3-5 m/min and the grinding thickness of 0.01-0.02 mm; and obtaining the microfiber synthetic leather after buffing.

5. The method for preparing microfiber synthetic leather according to any one of claims 1 to 4, wherein: it also includes the following steps:

step seven, dry process veneering:

firstly, selecting release paper, uniformly coating colorless film mixed slurry with the viscosity of 1200-1800 cps/25 ℃ on the front surface of the release paper, and drying at the temperature of 110 ℃ to prepare colorless film release paper;

uniformly coating mixed slurry with the viscosity of 1500-2000 cps/25 ℃ and fluorescent color on the surface of the colorless film release paper, and drying for 2-5 minutes by using an oven at 120-130 ℃ to obtain the fluorescent film release paper;

step eight, surface treatment:

uniformly coating an adhesive layer containing pigment with the viscosity of 2500-3500 cps/25 ℃ on the fluorescent film release paper;

and secondly, attaching the superfine fiber synthetic leather to the synthetic leather, drying the synthetic leather for 5 minutes at 120-150 ℃ by using an oven, and directly stripping the leather from release paper to obtain the finished product of the superfine fiber synthetic leather.

6. The preparation method of microfiber synthetic leather according to claim 3, wherein: in step one, an island fiber is prepared comprising the steps of:

s1, respectively carrying out pre-crystallization and drying treatment on the PBT polymer and the PA6 polymer;

s2, melting and extruding in screw machine presses with respective temperature control, filtering, metering and feeding into a spinning manifold;

s3, a special composite spinning assembly is arranged in the spinning manifold, the paths of two spinning components from the screw extrusion melting to the spinning manifold are independent, and then the spinning components reach the composite spinning assembly to realize the composite process instantly;

s4, cooling and solidifying the composite fiber filaments to obtain primary fibers;

s5, directly oiling, stretching, shaping and winding into finished yarn to obtain the sea-island fiber.

7. The preparation method of microfiber synthetic leather according to claim 3, wherein: in the third step, after the non-woven fabric is woven into a finished product, a post-treatment process is required, and the process flow comprises dipping, coating, printing, dyeing, tentering and setting, singeing, hot rolling, water repellency, flame retardance and slitting into rolls.

8. The preparation method of microfiber synthetic leather according to claim 3, wherein: in the fourth step, the preparation method of the polyurethane slurry comprises the following steps:

s1, adding quantitative DMF (dimethyl formamide) into a stirring cylinder, then adding wood powder, stirring to disperse the wood powder in the DMF, and stopping stirring;

and S2, sequentially adding C-70, S-80, water, a defoaming agent and a flatting agent into a stirring cylinder, continuously stirring for 5min, adding polyurethane resin and a coloring agent, stirring at a high speed for about 20min, and simultaneously carrying out vacuum defoaming to obtain the polyurethane slurry.

Technical Field

The invention relates to the technical field of microfiber synthetic leather manufacturing, in particular to microfiber synthetic leather and a preparation method thereof.

Background

The ultrafine fibers are also called microfibers, fine denier fibers, and ultrafine fibers, and fibers having a fineness of 0.3 denier (diameter of 5 μm) or less are generally called ultrafine fibers.

The superfine synthetic leather is a new high-grade artificial leather made of superfine fibre, can be used in various fields of shoes, bags, furniture, automotive interior and the like, and has the characteristics of genuine leather and indexes superior to genuine leather. Polyurethane synthetic leather using a three-dimensional network structure ultrafine fiber non-woven fabric as a base fabric is a new generation of synthetic leather developed in recent years, and is called fourth generation artificial leather, which is comparable to high-grade natural leather, has the inherent moisture absorption and air permeability of natural leather, and is superior to natural leather in chemical resistance, water resistance, mildew resistance and the like.

Although the prior superfine fiber synthetic leather has excellent properties, the prior superfine fiber synthetic leather also has some defects, firstly, the preparation process of the product is complex and the cost is high; secondly, the air permeability and the moisture permeability of the product still have good limitations and are easy to mildew or age; thirdly, after the product is used for a long time, the surface of the synthetic leather is easy to wear, so that the leather surface is stripped and the surface is faded, the service performance of the product is reduced, and the quality of the product is seriously influenced.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects in the prior art, the invention provides the microfiber synthetic leather and the preparation method thereof, which synchronously improve the raw materials and the process design of the product so as to reduce the manufacturing cost and improve the comprehensive performance of the product. The polyurethane is in a circular or needle-shaped foaming structure in a framework formed in sea-island fibers, and the hair ditch structures are communicated in a staggered mode to form a fine permeable structure, so that the leather body has good air permeability and moisture permeability, and the wear resistance and the adhesive force of the surface of the synthetic leather are good and the color and the transparency of the surface are kept unchanged through dry-process veneering and surface treatment processes, so that the product quality is greatly improved, the excellent abrasion resistance effect can be achieved, and the durability of the synthetic leather is improved.

(II) technical scheme

In order to realize the technical problem, the invention provides the following technical scheme:

the microfiber synthetic leather comprises base cloth, sea-island fibers and polyurethane, wherein the sea-island fibers and the polyurethane are tightly connected in the base cloth, the sea-island fibers and the polyurethane are tightly connected together, the three dimensions of the sea-island fibers are mutually crosslinked to form a dermis collagen fiber structure, the polyurethane is distributed around the sea-island fibers, the polyurethane is in a circular foaming structure in a framework formed by the sea-island fibers, and the base cloth, the sea-island fibers and the polyurethane are integrally in a three-dimensional net shape.

Further, the skeleton formed by the polyurethane on the sea-island fiber is a needle-shaped foaming structure.

A preparation method of microfiber synthetic leather comprises the following steps:

firstly, preparing sea-island fibers;

secondly, post-spinning the sea-island fiber: bundling, drafting and oil-dipping, curling, heat setting, cutting and packaging, wherein 4 continuous processes, namely primary drafting, secondary drafting, tertiary drafting and curling, are adopted in the process from drafting to curling;

step three, spinning the non-woven fabric, and spinning the post-spun sea-island fibers together to form a base fabric;

step four, wet impregnation: preparing polyurethane slurry in a soaking tank, then sending the base cloth, entering the soaking tank through a cloth storage rack, squeezing water in the base cloth by using a squeezing roller, ironing the base cloth by using an ironing wheel to be half-dried, ironing the base cloth at the same time, coating the matching slurry on a coating machine, entering a coagulating tank to form a skin membrane, fully washing, drying and shaping to obtain the microfiber synthetic leather.

Step five, alkali decrement: dissolving sodium hydroxide, a cation accelerator and a carrier for dyeing the polyester disperse dye in water to prepare an alkali liquor, and putting the microfiber synthetic leather obtained in the fourth step into the alkali liquor, wherein the alkali decrement bath ratio is 1: 5-100 ℃, heating to 60-80 ℃ at a heating rate of 5 ℃/min, preserving heat for 60-120 min, taking out the base fabric after heat preservation is finished, washing for 3-8 times, and drying at 70-85 ℃;

step six, splitting and grinding the skin: firstly, carrying out leather stripping on the microfiber synthetic leather on a leather stripping machine, wherein the speed of the leather stripping machine is 3-6 m/min, and the rotating speed of a blade of the leather stripping machine is 1000-1500 rpm, so as to obtain the microfiber synthetic leather after leather stripping;

secondly, grinding the bottom of the microfiber synthetic leather on a leather grinding machine by taking the top of the microfiber synthetic leather as a reference surface, wherein the number of sanded leather meshes of the leather grinding machine is 150-240 meshes, the rotating speed of the sanded leather is 1000-1300 rpm, the vehicle speed is 3-5 m/min, and the grinding thickness is 0.03-0.08 mm, and then grinding the top of the microfiber synthetic leather by taking the bottom of the microfiber synthetic leather as the reference surface, wherein the number of the sanded leather meshes is 240-480 meshes, the rotating speed of the sanded leather is 1000-1300 rpm, the vehicle speed is 3-5 m/min, and the grinding thickness is 0.01-0.02 mm; obtaining the microfiber synthetic leather after buffing;

step seven, dry process veneering

Firstly, selecting release paper, uniformly coating colorless film mixed slurry with the viscosity of 1200-1800 cps/25 ℃ on the front surface of the release paper, and drying at the temperature of 110 ℃ to prepare colorless film release paper;

uniformly coating mixed slurry with the viscosity of 1500-2000 cps/25 ℃ and fluorescent color on the surface of the colorless film release paper, and drying for 2-5 minutes by using an oven at 120-130 ℃ to obtain the fluorescent film release paper;

step eight, surface treatment

Uniformly coating an adhesive layer containing pigment with the viscosity of 2500-3500 cps/25 ℃ on the fluorescent film release paper;

and secondly, attaching the superfine fiber synthetic leather to the synthetic leather, drying the synthetic leather for 5 minutes at 120-150 ℃ by using an oven, and directly stripping the leather from release paper to obtain the finished product of the superfine fiber synthetic leather.

(III) advantageous effects

The microfiber synthetic leather and the preparation method thereof provided by the invention have the following beneficial effects:

1. the invention reduces the manufacturing cost and improves the comprehensive performance of the product by synchronously improving the raw materials and the process design of the product. Specifically, the polyurethane is in a circular or needle-shaped foaming structure in a framework formed in sea-island fibers, and the hair ditch structures among the polyurethane are communicated in a staggered mode to form a fine permeable structure, so that the leather body has good air permeability and moisture permeability, and the surface of the synthetic leather is good in wear resistance and strong in adhesive force through dry-process veneering and surface treatment procedures, and meanwhile, the color and the transparency of the surface are kept unchanged, so that the product quality is greatly improved, the synthetic leather has an excellent anti-abrasion effect, and the durability of the synthetic leather is improved.

2. According to the method and the product provided by the invention, the surface of the superfine fiber generates corrosion peeling effect by carrying out alkali deweighting treatment on the synthetic leather, so that the diameter is thinned, the hand feeling is softened, and the gaps between warps and wefts are enlarged after deweighting, so that the fiber has increased activating degree and the drapability is obviously improved, therefore, the method and the product have good rebound resilience and hand feeling, and meanwhile, the wear resistance of the surface of the product is obviously improved.

3. The product provided by the invention adopts the sea-island fibers as the framework, the fineness of the sea-island fibers is extremely small, the leather can be soft and smooth in hand feeling, the product has obvious advantages in comfort, high tightness, moisture absorption and water repellency can be obtained, the product has unique aesthetic property, the whole product has excellent waterproof and vapor permeability, and the microporous structure among the fibers allows more static air to be contained in the leather, so that the product can obtain better heat insulation and warm keeping effects.

4. The product provided by the invention not only has a microstructure similar to that of natural leather, but also has good moisture permeability and dimensional stability, and various fastnesses are superior to those of the natural leather, and the defects of large unevenness and small effective utilization rate of natural products caused by differences of animal types, sizes and parts are overcome, and in addition, the phenomena that the natural leather is easy to become damp, mildewed and smelly due to the fact that own protein fibers are easy to suffer from dampness are overcome, so that the product has obvious high-quality performance.

Drawings

FIG. 1 is a schematic structural diagram of a microfiber synthetic leather product according to the present invention.

In the figure: 1. a base cloth; 2. an island in the sea fiber; 3. a polyurethane.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, the microfiber synthetic leather provided by the present invention comprises a base cloth 1, sea-island fibers 2 and polyurethane 3, wherein the sea-island fibers 1 and the polyurethane 2 are tightly connected in the base cloth 1, the sea-island fibers 1 and the polyurethane 2 are tightly connected together, the three dimensions of the sea-island fibers 1 are cross-linked together to form a dermal collagen fiber structure, the polyurethane 2 is distributed around the sea-island fibers 1, the polyurethane 2 is a circular foam structure in a framework formed by the sea-island fibers 1, the base cloth 1, the sea-island fibers 2 and the polyurethane 3 are integrally in a three-dimensional net shape, and the framework formed by the sea-island fibers 1 by the polyurethane 2 can also be in a needle-shaped foam structure.

A preparation method of microfiber synthetic leather comprises the following steps:

firstly, preparing sea-island fibers;

the method for manufacturing the sea-island fiber comprises the following steps:

s1, respectively carrying out pre-crystallization and drying treatment on the PBT polymer and the PA6 polymer;

s2, melting and extruding in screw machine presses with respective temperature control, filtering, metering and feeding into a spinning manifold;

s3, a special composite spinning assembly is arranged in the spinning manifold, the paths of two spinning components from the screw extrusion melting to the spinning manifold are independent, and then the spinning components reach the composite spinning assembly to realize the composite process instantly;

s4, cooling and solidifying the composite fiber filaments to obtain primary fibers;

s5, directly oiling, stretching, shaping and winding into finished yarn to obtain the sea-island fiber.

Secondly, post-spinning the sea-island fiber, wherein the post-spinning process of the sea-island fiber comprises bundling, drafting and oil immersion, curling, heat setting, cutting and packaging, and 4 continuous processes, namely primary drafting, secondary drafting, tertiary drafting and curling, are performed in the process from drafting to curling;

step three, spinning the non-woven fabric, spinning the post-spun sea-island fibers together to form a base fabric, and performing a post-treatment process after the non-woven fabric is spun into a finished product, wherein the process flow comprises impregnation, coating, printing, dyeing, tentering and setting, singeing, hot rolling, water repellency, flame retardance and slitting into rolls;

step four, wet impregnation: preparing polyurethane slurry in a soaking tank, then sending the base cloth, entering the soaking tank through a cloth storage rack, squeezing water in the base cloth by using a squeezing roller, ironing the base cloth by using an ironing wheel to be half-dried, ironing the base cloth at the same time, coating the matching slurry on a coating machine, entering a coagulating tank to form a skin membrane, fully washing, drying and shaping to obtain the microfiber synthetic leather.

The preparation method of the polyurethane slurry comprises the following steps:

s1, adding quantitative DMF (dimethyl formamide) into a stirring cylinder, then adding wood powder, stirring to disperse the wood powder in the DMF, and stopping stirring;

and S2, sequentially adding C-70, S-80, water, a defoaming agent and a flatting agent into a stirring cylinder, continuously stirring for 5min, adding polyurethane resin and a coloring agent, stirring at a high speed for about 20min, and simultaneously carrying out vacuum defoaming to obtain the polyurethane slurry.

Step five, alkali decrement: dissolving sodium hydroxide, a cation accelerator and a carrier for dyeing the polyester disperse dye in water to prepare an alkali liquor, and putting the microfiber synthetic leather obtained in the fourth step into the alkali liquor, wherein the alkali decrement bath ratio is 1: 5-100 ℃, heating to 60-80 ℃ at a heating rate of 5 ℃/min, preserving heat for 60-120 min, taking out the base fabric after heat preservation is finished, washing for 3-8 times, and drying at 70-85 ℃.

Step six, splitting and grinding the skin:

firstly, carrying out leather stripping on the microfiber synthetic leather on a leather stripping machine, wherein the speed of the leather stripping machine is 3-6 m/min, and the rotating speed of a blade of the leather stripping machine is 1000-1500 rpm, so as to obtain the microfiber synthetic leather after leather stripping;

secondly, grinding the bottom of the microfiber synthetic leather on a leather grinding machine by taking the top of the microfiber synthetic leather as a reference surface, wherein the number of sanded leather meshes of the leather grinding machine is 150-240 meshes, the rotating speed of the sanded leather is 1000-1300 rpm, the vehicle speed is 3-5 m/min, and the grinding thickness is 0.03-0.08 mm, and then grinding the top of the microfiber synthetic leather by taking the bottom of the microfiber synthetic leather as the reference surface, wherein the number of the sanded leather meshes is 240-480 meshes, the rotating speed of the sanded leather is 1000-1300 rpm, the vehicle speed is 3-5 m/min, and the grinding thickness is 0.01-0.02 mm; and obtaining the microfiber synthetic leather after buffing.

Step seven, dry process veneering

Firstly, selecting release paper, uniformly coating colorless film mixed slurry with the viscosity of 1200-1800 cps/25 ℃ on the front surface of the release paper, and drying at the temperature of 110 ℃ to prepare colorless film release paper;

uniformly coating mixed slurry with the viscosity of 1500-2000 cps/25 ℃ and fluorescent color on the surface of the colorless film release paper, and drying for 2-5 minutes by using an oven at 120-130 ℃ to obtain the fluorescent film release paper;

step eight, surface treatment

Uniformly coating an adhesive layer containing pigment with the viscosity of 2500-3500 cps/25 ℃ on the fluorescent film release paper;

and secondly, attaching the superfine fiber synthetic leather to the synthetic leather, drying the synthetic leather for 5 minutes at 120-150 ℃ by using an oven, and directly stripping the leather from release paper to obtain the finished product of the superfine fiber synthetic leather.

The invention reduces the manufacturing cost and improves the comprehensive performance of the product by synchronously improving the raw materials and the process design of the product. Particularly, the framework formed by polyurethane in the sea-island fiber is a circular or needle-shaped foaming structure, the hair channel structures are communicated in a staggered way to form a fine transparent structure, so that the leather body has good air permeability and moisture permeability, and the dry process veneering and surface treatment processes are carried out, so that the synthetic leather surface has good wear resistance and strong adhesive force, meanwhile, the color and the transparency of the surface are kept unchanged, the quality of the product is greatly improved, the wear-resistant effect is excellent, thereby improving the durability of the synthetic leather, the invention generates the corrosion peeling effect on the surface of the superfine fiber by carrying out alkali decrement treatment on the synthetic leather, so the diameter is thin, the hand feeling is soft, and the gaps between the warps and the wefts are enlarged after the weight is reduced, so that the loose degree of the fibers is increased, and the drapability is obviously improved, so that the fiber has good rebound resilience and hand feeling.

The invention adopts the sea-island fiber as the framework, the fineness of the sea-island fiber is very small, the leather can be enabled to have soft and smooth hand feeling, the comfort is obvious, the leather has high tightness, hygroscopicity and water repellency, the appearance is unique, the whole leather has excellent waterproof and vapor permeability, the microporous structure among the fibers allows more static air in the leather, and therefore, the invention can obtain better heat insulation and warm keeping effects, therefore, the invention not only has the characteristics of non-ironing, good dimensional stability, small shrinkage rate and the like of the synthetic leather, but also has the advantages of good drapability, moisture permeability and the like of the natural leather, the invention not only has a microstructure similar to the natural leather, but also has good moisture permeability and dimensional stability, and each fastness is superior to the natural leather, and the problem that the natural product has large unevenness caused by the difference of the animal types, the sizes and the parts is avoided, The defect of low effective utilization rate, and in addition, the phenomenon that the natural leather is easy to become damp, mildewed and smelly due to self protein fiber is also overcome, so that the natural leather has obvious high-quality performance.

The method and the product provided by the invention can enable the leather body to have good air permeability and moisture permeability, and through the dry veneering and surface treatment processes, the wear resistance of the surface of the synthetic leather is good, the adhesive force is strong, meanwhile, the color and the transparency of the surface are kept unchanged, the quality of the product is greatly improved, and the product has an excellent wear resistance effect, so that the durability of the synthetic leather is improved.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.