US3354486A - Mulling process - Google Patents

Description

United States Patent M 3,354,486 MULLING PROCESS Arthur Bradshaw, Kenneth Lee, Norman Swales, and Peter Wilfred Voyle, Leicester, England, assignors to United Shoe Machinery Corporation, Flemington, N.J., a corporation of New Jersey No Drawing. Filed Sept. 23, 1964, Ser. No. 398,751 Claims priority, application Great Britain, Oct. 26, 1963, 42,301/63 4 Claims. (Cl. 12142) This invention relates to a method of conditioning leather and, more specifically, to a process of mulling or tempering an article of leather to distribute moisture therethrough.

The shoemaking industry has been involved throughout its history in a constant and penetrating search for technical improvements and, in recent years, for methods and apparatus which facilitate increased automation. One of the principal operations in the shoemaking cycle which has impeded the advancement toward complete automation is the mulling or tempering of the leather. The purpose of mulling or tempering is to render the leather more workable thereby to permit flexing and stretching thereof. Thus, mulling or tempering is an important prerequisite to a large number of shoemaking procedures.

Heretofore, a common method employed for mulling or tempering leather has been to house the leather in a moist atmosphere for an extended period of time thereby to ensure the distribution of Water throughout the leather. Another method of tempering leather was accomplished by dipping it in cold water for a period of hours and allowing it to drain. The result of these operations was uniformly moistened leather which was easily Worked. The procedure was, however, time consuming and, therefore, costly. Further, it did not lend itself to automation and diluted the value of the automation of appurtenant operations. The need for a method of mulling or tempering leather which would facilitate the integration of these operations into an automated shoemaking cycle has been long felt and desired. Adequate mulling or tempering could not be sacrificed for increased automation due to the detrimental efiects on operations dependent thereon. To do so would be to thwart the purpose of automation.

In view of the foregoing, an object of the present invention is to provide an improved method of conditioning leather which materially decreases the time required for the mulling or tempering thereof.

To this end and in accordance with a feature of the present invention, there is provided a method of conditioning leather shoe parts comprising subjecting the shoe part to a high temperature moist atmosphere and directing a spray of relatively cold water onto the shoe part one or more times during the exposure of the shoe part to the high-temperature moist atmosphere.

The above and other features of the invention will now be described; it being clearly understood that the method to be described and claimed is equally applicable to materials used as a substitute for leather.

In order to appreciate the technological advantages and novelty of the present invention an understanding of the phenomenon which facilitates the implementation of the method is necessary. When a leather article is introduced to a high-temperature moist atmosphere having a dew point above the initial temperature of the article, a film of water is precipitated on the surface of the article so that condensation forms on the surfaces of the article. If the article is permeable and if the article has not previously been moistened to a level which results in moisture equilibrium, the film of water will be absorbed and pass into the interior of the article. The result is a rapid absorption of moisture by the article. However, since the article is exposed to the high temperature of the atmos- Cir 3,354,486 Patented Nov. 28, 1967 phere and the heat of condensation generated by the water film, the temperature of the article will be gradually elevated until it reaches and passes the dew point of the atmosphere. When the temperature of the article passes the dew point of the atmosphere, evaporation of moisture from the article will result.

In the application of the method of the subject invention, a leather shoe part is introduced to a relatively hightemperature moist atmosphere. In the preferred embodiment, the atmosphere comprises saturated water vapor in a temperature range of F. to F. The preferred period of exposure is approximately five minutes, i.e. when the other parameters stated to be preferred are present. This period of exposure facilitates integration of the mulling or tempering operations into an automated shoemalring cycle and provides adequate mulling without requiring the use of extreme humidity and/or temperature conditions.

When the leather shoe part initially is introduced to the atmosphere, the dew point of the atmosphere is above the temperature of the shoe part. Accordingly, condensation will initially form on the shoe part and rapidly will be absorbed thereby. This phenomenon will continue at a rapid rate until the temperature of the shoe part closely approaches the dew point of the atmosphere.

At a predetermined time during the exposure interval of the shoe part to the high-temperature humid atmosphere, a spray of relatively cold water is directed onto the surface areas of the shoe part, i.e. water below the dew point of the atmosphere. The exact point during the exposure interval at which the cold spray is applied is that point at which the temperature of the shoe part has been elevated to the dew point of the atmosphere. That is, the point at which the formation of condensation will stop and evaporation will begin. The spray of cold water lowers the temperature of the shoe part relative to the dew point of the atmosphere thereby to effect continued disposition of condensation onto the shoe part. The process may be repeated as many times as is necessary to maintain continuity in condensation formation. The exact points during a given exposure interval at which the cold spray must be directed onto the shoe part is determined by the initial temperature of the shoe part and the dew point of the atmosphere.

In the preferred embodiment of the invention, the water is sprayed onto the shoe part at relatively low temperature, viz. tap water. Further, it is preferred that the spray of cold water be obtained by atomizing the water to minimize the disturbance of the high-temperature moist atmosphere. When practicing the method in the preferred embodiment, a single spray three to four minutes after introduction for from 3 to 15 seconds is suflicient to ensure continuous formation of condensation on the shoe part.

The cold water spray can also be utilized to lower the temperature of a shoe part when it is initially introduced to the high-temperature moist atmosphere or before it is introduced. When the invention is practiced in this embodiment, the shoe part is sprayed with cold water before introduction or just after it is introduced to the atmosphere and may be sprayed a second time when the five minute exposure interval has been approximately half completed, i.e. assuming the other parameters conform to the requirements of the preferred embodiment.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. A method of conditioning leather comprising subjecting a leather article to a high temperature moist atmosphere and directing relatively cold water onto the article during the period of exposure of the leather article to said atmosphere, thereby to lower the temperature of said article below the dew point of said atmosphere, wherebytoetfectcontinued disposition of condensation on said article.

2. A method of conditioningleather comprising subjecting a leather article to a high-temperature moist atmosphere having a dew point above the initial temperature of the leather article and directing a spray of relatively cold water onto the surface areas of the article at least once during the period of exposure of the leather article to said *atmosphere, thereby to lower the temperature of said article below the dew point of said atmosphere, whereby to eflfeet continued disposition of condensationon said article.

3. A method of conditioningleather comprising subjecting a leatherlarticle to a high temperature moist atmos: phere, said atmosphere being in the temperature range, of 130 F. to- 150 F. and having a dew point above the initialtemperature of the leather article, and directing a spray of relatively cold water onto the article during the period of exposure thereof to said atmosphere, thereby to lower the temperature of'said article below the dew point of said atmosphere, whereby to effect continued disposi: tion of condensation on said article.

4. A method of conditioning leather comprising subiecting a leather article to a high temperature moist atmosphere for a period of approximately five minutes, said atmosphere being'inthe temperature range of F. to F. and having a dewpoint above the initial temperature of leather article, and directing a spray of relatively cold water onto the leather article at least once during the period of'exposure thereof to said atmosphere.

ReferencessCited UNITED STATES PATENTS 2,973,53l 3/1961 Bromfield 12-l42 3,176,333 4/196'5 Maeser a l2l42 3,203,018 8/1965 Klein 12-142 X PATRICK D. LAWSON, Primary Examiner.

Claims (1)

1. A METHOD OF CONDITIONING LEATHER COMPRISING SUBJECTING A LEATHER ARTICLE TO A HIGH TEMPERATURE MOIST ATMOSPHERE AND DIRECTING RELATIVELY COLD WATER ONTO THE ARTICLE DURING THE PERIOD OF EXPOSURE OF THE LEATHER ARTICLE TO SAID ATMOSPHERE, THEREBY TO LOWER THE TEMPERATURE OF SAID ARTICLE BELOW THE DEW POINT OF SAID ATMOSPHERE, WHEREBY TO EFFECT CONTINUED DISPOSITION OF CONDENSATION ON SAID ARTICLE.