Fluent material handling – with receiver or receiver coacting mea – Processes – Battery grid pasting
Patent
1979-09-26
1982-06-01
Schmidt, Frederick R.
Fluent material handling, with receiver or receiver coacting mea
Processes
Battery grid pasting
118323, 118DIG16, 141131, 222423, 427424, B05B 302, B65B 304
Patent
active
043322816
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
The present invention relates to a method and apparatus for spreading a foamable composition for forming a polyurethane foam.
The present invention especially relates to a method and apparatus for spreading a foamable composition on a surface which relatively moves to a spreader to form a uniform polyurethane foam layer.
BACKGROUND OF TECHNOLOGY
A polyurethane foam is prepared by foaming and setting a foamable composition comprising main components of an active hydrogen compound having at least two active hydrogen atoms and an isocyanate compound having at least two isocyanate groups. The foamable composition can comprise a blowing agent, a catalyst, a foam regulator etc. together with the two main components. Sometimes, it further comprises additional components such as flameproofing agent, a coloring agent, a stabilizer, a filler etc.
The foamable composition usually begins to cause foaming within at least several tens seconds after the blending and completes the foaming within several to ten and several minutes after the blending. Tackiness of the surface is lost to complete the setting at certain time after completing the foaming.
In the technical field, a period from the completion of the blending to the time just before blowing a white creamy liquid of the foamable composition in the initiation of foaming is called as a cream time, and a period for blowing the creamy liquid to grow a foam and to complete the blowing is called as rise time and a period for setting the surface of the foam after the rise is called as set time.
It is relatively difficult to form a uniform thin foamable composition layer by spreading a foamable composition obtained by mixing components from a feeding outlet to a surface which is relatively moved to the feeding outlet.
These surfaces for relatively moving include slab belt surface, a mold inner wall and a plate surface. The feeding outlet of a mixer is usually in a form of holes. Therefore, even though a foamable composition is fed on a surface which is relatively moved to the feeding outlet, the foamable composition is placed in the form of strips on the surface. In the conventional slab formation of a soft polyurethane foam, such process has been employed. Since the foamable composition has low viscosity, the foamable composition is spread on the surface of the slab belt by its dead weight and the three-dimentional blowing is resulted and the foamable composition is expanded to required width since the blowing rate is large. When the width of the slab belt is large, the feeding outlet is reciprocated in the transversal direction of the slab belt so as to place the foamable composition in zig-zag on the surface of the slab belt. It is difficult to employ said method when a foamable composition for a hard polyurethane foam has high viscosity or a foamable composition should be placed in thin thickness for forming a thin polyurethane foam or a blowing rate of a foamable composition is low.
A method for distributing a foamable composition on a whole surface which is relatively moved to a linear feeding outlet for the foamable composition which is arranged to a perpendicular direction to the moving direction of the relative movement has been known. For example, in the specification of U.S. Pat. No. 3,927,162, a method for feeding a foamable composition on a whole inner surface of a moving mold from a sector feeding outlet is described. However, in this method, in order to discharge uniformly a foamable composition from all part of the linear feeding outlet, a pressure being higher than certain degree is required. When the pressure is lower than this degree, a discharge from the top of the feeding outlet is difficult. When a width of the feeding outlet is narrower without varying its length to reduce a feeding rate of the foamable composition, the clogging of the foamable composition is easily caused to be difficult feeding uniformly. A foamable composition is foamed and set for a short time, whereby the clogging of the feeding outlet is caused by the f
REFERENCES:
patent: 1588062 (1926-06-01), Spivey
patent: 2209366 (1940-07-01), Vane
patent: 3193406 (1965-07-01), Mittelmans
patent: 3681485 (1972-08-01), Lieberman
patent: 3927162 (1975-12-01), Stalter, Sr.
patent: 3932980 (1976-01-01), Mizutani et al.
Asahi Glass Company Ltd.
Baba Seisakusho Co., Ltd.
Schmidt Frederick R.
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