Patent Application
20060288493
The present invention relates to methods for the production of leather, and more particularly to a process for producing leather suitable for use as a lining material in footwear.
Leather is used in a wide variety of applications. One of the most common uses of leather is in footwear. In the context of footwear, leather may be used to form nearly every element of the article of footwear. For example, the upper, sole and even the laces may be manufactured from leather. Leather may also be used to form a lining material for the article of footwear. In this context, a layer of leather may sewn or other be used to line the inside of the upper to provide a comfortable surface to engage the wearer's foot. Leather lining materials are typically soft and supple while at the same time being relatively durable.
It is often desirable to provide waterproof footwear. Waterproof footwear is used in variety of settings, such as hunting, fishing, hiking and other outdoor applications. One conventional technique for manufacturing waterproof footwear is to form a waterproof bootie that is removably fitted inside the upper. A conventional bootie is shaped much like a sock and is intended to fit snuggly within the upper and snuggly around the wearer's foot. These booties can be relatively expensive to manufacture and may adversely affect the comfort and weight of the article of footwear. They can also be inconvenient to use because they can be pulled from inside the boot when the wearer's foot is removed, thereby requiring repeated reinsertion. Another conventional technique for manufacturing waterproof footwear is to form the upper from a material that is waterproof and sufficiently durable for the intended application. This type of manufacture is complicated by the need to use relatively complex techniques for providing a waterproof seam or interface between the upper material and the sole.
Despite the widespread use of leather in footwear construction, the prior art is devoid of a leather tailored for use as waterproof footwear lining material. Leather production is a complex process in which efforts to enhance one desirable characteristic of the leather can have an unanticipated negative impact on other desired characteristics of the leather. As likely the result of the complexities associated with leather manufacture, there remains an unmet need for a waterproof and antimicrobial leather that is sufficiently soft, supple are durable enough to function as a lining material for footwear.
The aforementioned problems are overcome by the present invention wherein a process is provided for producing a lightweight leather that is waterproof and breathable. The material also includes antimicrobial characteristics and is highly perspiration resistant and colorfast. The production process generally includes the steps of: (a) providing wet blue, full grain skins, (b) applying a surfacant/degreasing agent to the skins, (c) applying an emulsifying agent to the skins, (d) neutralizing the skins to provide the skins with a pH level of in the range of about 7.0 or greater, (e) applying a waterproofing agent to the skins, (f) applying a tanning agent to the skins, (g) fixing the waterproofing agent and tanning agent in the skins without chrome or other metal salts while reducing the pH level to within the range of about 3.0 to 3.5, (h) applying an antimicrobial treatment to the skins, (i) applying a waterproofing agent to the skins, (j) applying a leather protectant to the skins and (k) fixing the skins without chrome or other metal salts while moving the pH level to within the range of about 3.0 to 3.5. If desired, the skins can also be subjected to additional treatments, such as flame resistant/flame proof treatments.
In one embodiment, the step of applying a waterproofing agent to the skins is further defined as applying both a silicone-based waterproofing agent and a paraffin-based waterproofing agent to the skins. In one embodiment the paraffin-based waterproofing agent is applied to the skins first and the silicone-based waterproofing agent is applied second. In another embodiment, the second step of applying a waterproofing agent to the skins includes applying a silicone-based waterproofing agent to the skins.
In one embodiment, the antimicrobial treatment and leather protectant are applied to the skins in a fluorchemical process. In another embodiment, the second step of applying a waterproofing agent is also carried out in fluorchemical process.
The present invention produces a breathable, yet water protective leather. The leather is lightweight and comfortable, yet durable to provide a long lasting lining material. The leather has desirable perspiration resistance, which among other things resists color transfer to other materials, such as the wearer's sock. The leather protectant step also provides the leather with a high degree of stain/oil resistance. The antimicrobial treatment also provides the leather with highly desirable anti-fungal characteristics. As a result of these characteristics, the process is particularly well-suited for use in producing leather to be use as a waterproof lining for footwear.
These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.
An embodiment of the present invention is described in connection with the flowchart of
The following description sets forth an embodiment of the present invention that is optimized to provide finished leather with a particular set of desired characteristics. Those skilled in the field will readily appreciate that the specified times and quantities are approximate and that some variation in a specified time or in a specified quantity will typically yield acceptable results in the finished leather, and adjustments can be used to intentionally adjust the characteristics of the finished leather. The amount of acceptable variation in a particular time or quantity will vary depending primarily on the amount of acceptable variance in the finished leather. For example, variations in the range of approximately ±20% in the quantity of a particular additive are likely to be acceptable for each of the additives, except for the acidic and caustic materials used to adjust the pH level of the float (i.e. formic acid, sodium formate, sodium bicarbonate and aqua ammonia). However, even with the acidic and caustic materials, variation in the quantity of a particular additive may be compensated for by adjustment in the strength (e.g. percent of composition) of the additive or in time that the mill is run with the additive in the float provided that the specified pH levels are obtained. It should further be noted that, in the following paragraphs, the percentages of various additives are specified in parentheses following the specified weight or volume quantities. These percentages refer to the weight of the additive with respect to the total weight of the wet blue skins being processed. Additionally, unless specifically set forth in the claims, the order of steps set forth in this description is intended to be exemplary and is not intended to require the steps of the present invention to be performed in any specific order.
In the illustrated embodiment, the process begins by loading the wet blue skins into a conventional mill. In this embodiment, approximately 500 lbs. of skins are loaded into the mill. Typically, the wet blue skins have a pH of 3.5 or lower. As a first step, the skins may be washed. Initially, approximately 400 gallons of water are added to the mill. The water may be at a temperature of approximately 140° Fahrenheit (F.), but the temperature may vary, for example, between 105°-150° F. The skins are washed and then the water is drained from the mill.
After the initial washing step, the skins undergo the degreasing and neutralizing phase 20, 30 (See
Following these steps, the skins are washed and neutralized 30 (See
In the second stage, 50 gallons of water is added 112 to the mill to establish the float. The water is preferably at a temperature of approximately 110° F., but the temperature may vary, for example, between 90-120° F. Following this, approximately 1.25 lbs. of Limenal PEW, 10.0 lbs. of sodium acetate (or 2%) is added 114 to the mill and 10.0 lbs. of sodium formate (or 2%) is added 116 to the mill. The mill is then run 120 for approximately 30 minutes. Limenal PEW is an emulsifying agent, and it may be replaced by other emulsifying agents of corresponding amounts.
In the third stage, approximately 10.0 lbs. of sodium bicarbonate (or 2%) is added 122 to the mill and 2.5 lbs. of sodium acetate (or 0.5%) is added 124 to the mill. The mill is then run 126 for approximately 90 minutes. The mill running time may vary, for example, between 90-120 minutes. The process is likely to provide the skins with a pH value of approximately 7.0 or higher.
The neutralized skins are next subjected to the waterproofing phase 40 (See
The skins next undergo a retanning process 50. In the desired embodiment, approximately 15.0 lbs. of Tanigan BN (or 3%) is added 140 to the mill and the mill is run 142 for approximately 30 minutes. Tanigan BN is synthetic tanning agent available from (available from Lanxess (formerly Bayer) of Pittsburgh, Pa.). This synthetic tanning agent may be replaced by other tanning agents—natural or synthetic.
The skins next pass into the fixation phase 60. To aid in fixing the waterproofing agents and retanning agent in the skins, formic acid is added to the mill in two sequential installments. First, approximately 5.0 lbs. (1%) of formic acid (90% concentration) is mixed 148 with approximately 5.556 gallons of water at approximately 100° F. The mixture is added 150 to the mill. The mill is run 152 for approximately 15 minutes. The runtime of the mill may vary, for example, between 10 to 40 minutes. Then, a second installment of approximately 5.0 lbs. (1%) of formic acid (90% concentration) and 5.556 gallons of water at approximately 100° F. are mixed 154 and added 156 to the mill. The mill is then run 158 for approximately 15 minutes. Finally, a third installment of approximately 5.0 lbs. (1%) of formic acid (90% concentration) and 5.556 gallons of water at approximately 100° F. are mixed 160 and added 162 to the mill. The mill is again run 164 for approximately 15 minutes. The runtime of the mill may vary, for example, between 10 to 40 minutes. This should bring the skins to a pH level below approximately 3.5.
The skins are next subjected to a fluorchemical process 70 in which an antimicrobial agent, a leather protectant and a waterproofing agent are introduced to the skins. To prepare for this process, the skins are washed 166 in approximately 1000 gallons of water at approximately 135° F., and the mill is drained. The temperature of the water may vary, for example, between 115 to 150° F. The fluorchemical process begins by adding 168 approximately 55.556 gallons of water at approximately 135° F. to the mill to establish the float. Next, approximately 2.0 lbs. (0.4%) of Amical WP is dry fed 170 into the mill, and the mill is run 172 for approximately 10 minutes. Amical WP is a conventional antimicrobial treatment that is available from Chemtan Company, Inc. of Exeter, N.H. This additive may be replaced or supplemented with other antimicrobial agents. The runtime of the mill may vary, for example, between 10 to 20 minutes. Following this step, the skins are subjected to a second waterproofing phase 80. In this phase, approximately 15.0 lbs. (3%) of Xeroderm S-AF (available from Lanxess (formerly Bayer) of Pittsburgh, Pa.) is mixed 174 with approximately 5.556 gallons of water at approximately 90° F. The mixture is added 176 to the mill. The mill is run 178 for approximately 20 minutes. The runtime of the mill may vary, for example, between 10 to 30 minutes. After, the skins undergo a leather protectant phase 90. In this phase, approximately 15.0 lbs. (3%) of PM 4700 is mixed 180 with approximately 5.556 gallons of water at approximately 120° F. The mixture is added 182 to the mill, and the mill is run 184 for approximately 30 minutes. The runtime of the mill may vary, for example, between 20 to 60 minutes. The PM 4700 is a conventional leather protectant that renders the skins oil resistant and water resistant, and is available from 3M under the trade name “Scotch Guard®.” This protectant can be replaced or supplemented by other conventional protectants, if desired.
The skins are next treated to fix 100 the various agents in the skins. Approximately 5.0 lbs. (1%) of formic acid (90% concentration) is mixed 186 with approximately 5.556 gallons of water at approximately 100° F. The mixture is added 188 to the mill. The mill is run 190 for approximately 15 minutes. The runtime of the mill may vary, for example, between 5 to 45 minutes). These steps should bring the skins to a pH level in the range of 3.0 to 3.5.
If desired, additional treatments may be applied to the skins. For example, antistatic, flame resistant or flame proof treatments may be applied. The flame resistant or flame proof treatment may be applied to the skins in a dry or dissolved state, as desired. Further, additional antimicrobial treatments may be applied. Additional antimicrobial treatments may also be applied in a dry or dissolved state.
Next, the skins are subjected to a final washing. Approximately 1000 gallons of water at 100° F. are added to the mill while the mill is running. The washing door of the mill may be left open, permitting the water to slosh from the mill. The mill is run until nearly all of the water has sloshed from the mill. Then, the skins or leathers are dumped from the mill.
The leathers are preferably dried using conventional vacuum dryers or other similar machinery. The dried leathers can be staked and finished as desired. Staking is a mechanical softening process that typically involves beating the leather repeatedly with small fingers. The leathers can also be sanded and milled, as appropriate. The leathers can undergo additional finishing, as desired. For example, oil can be applied to the leather to add to waterproofness and change the look and feel of the leather. In the described embodiment, the finished leather may have a thickness ranging between 0.8 to 1.0 millimeters, which corresponds to a weight of approximately 2.0 to 2.5 ounces.
The above description is that of a preferred embodiment of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.
This application is a continuation-in-part of U.S. application Ser. No. 11,166,760, which was filed on Jun. 24, 2005, by Franciscus Cornelis Marie Metsaars.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11166760 | Jun 2005 | US |
| Child | 11458846 | Jul 2006 | US |
