US3287092A - Apparatus for processing polyurethane - Google Patents

Description

NOV. 22, 1966 J SCUDDER APPARATUS FOR PROCESSING POLYURETHANE Original Filed March 14. 1962 INVENTOR.

United States Patent APPARATUS FOR PROCESSING POLYURETHANE John A. Scudder, Chicago, Ill., assiguor to Chemechanical, Inc., South Holland, 11]., a corporation of Illinois Original application Mar. 14, 1962, Ser. No. 179,750.

Divided and this application Mar. 5, 1965,Ser. No.

6 Claims. (Cl. 23-485) This application is a division of my application Serial No. 179,750, filed March 14, 1962 and now abandoned.

The invention relates to improvements in apparatus for processing polyurethane.

Polyurethane, as commercially available, to be useful as a free flowing coating material for forming up wheel treads, roller surfaces and belting, preferably is degassed and catalyzed. This is accomplished by means of the apparatus of the present invention, which is designed to process the polyurethane in small quanties. Specifical- 1y, a container of pre-heated commercial liquid urethane prepolymer, such as for example, a product known commercially as Du Pont Adiprene L315 and the like, is placed in a sealed chamber which is evacuated at a regulated rate and to a temperature that is under constant surveillance so as to etlect degasification. When the material is completely degassed, and while still contained in the apparatus, its temperature is lowered and a measured quantity of a diamine curing :agent or like catalyst is admitted into the evacuated chamber while the mass is beingdisturbed by an impeller so as to blend the mixture for a proper length of time to insure uniform blending. The apparatus is such that the exact catalyzing temperature, pressure and chemical reaction is made known at all times during processing. Du Pont Adiprene L-315 is comprised of isocyanate terminated liquid elastomer having a specific gravity of about 1.0 at 25 C., and a viscosity of about 15,000 centipoise at about 30 C. Its NCO content is about 9.45%

It is therefore an object of the invention to provide a novel apparatus for degasifying and catalyzing polyurethane.

Another object is to provide apparatus that is not expensive to manufacture or maintain in service, and one that is extremely eflicient and which may be operated at low cost.

The structure by means of which the above noted and other advantages and objects of the invention are attained will be described in the following specification, taken in conjunction with the accompanying drawings, showing a preferred illustrative embodiment of the invention, in which:

FIG. 1 is an elevational view of a representative apparatus of the type disclosed herein.

FIG. 2 is a vertical central sectional view of the apparatus, showing parts in elevation.

FIG. 3 is a sectional plan view of the apparatus, taken substantially on line 33 of FIG. 1.

FIG. 4 is an enlarged fragmentary detail sectional view of the chamber wall and sealing pad.

The apparatus disclosed herein in exemplary from and embodying the invention comprises a support surface 11 having a plurality (3 shown) of upstanding supports 12 mounting, as by means of radial fins or webs 13, a cylindrical chamber wall 114. Also mounted on and extending below the support surface 11 and in axial alignment with chamber wall 14, is a cylinder-piston assembly 15, the piston 16 of which mounts on its upper end a rigid floor plate 17 having seated thereon a resiliently compressible pad 18. The pad 18, which preferably is rubber, is of a size to overly and embed the bottom peripheral edge 19 of chamber wall 14 when the pad and its support or' floor plate 17 are carried into abutment with said edge in a manner to be described presently.

Also mounted on one or more of the upstanding supports 12, and spaced above chamber wall 14, is radially extending arm or platform 21 which supports a power operated motor 22 having its driven shaft 23 extending downwardly axially into the interior of the chamber 24 defined by chamber wall 14. Preferably, the shaft extends through a sleeve 25 and upon which is mounted for vertical movement, a sheet 26 of suitable transparent material, such as for example, Plexiglas. The sheet 26 is adapted normally to be seated upon the upper peripheral edge of chamber wall 14, a sealing ring 27 being interposed therebetween, and affords means for observing the degassing operation.

The shaft 23 within chamber 24 mounts a pair of axially spaced impellers 28. A temperature gauge 29 is mounted on the top surface of the transparent sheet 26 with its effective stem 30 extending downwardly therefrom for a suitable distance.

In so far as the apparatus has been described, it is placed in use by initially positioning a can or other container 31 of commercial polyurethane on pad 18 while the latter is in the lowered position illustrated in FIG. 1. As is well understood in this art, the polyurethane is pre-heated to a temperature of about 187 F. to 250 F. so as to reduce its viscosity and insure maximum workability. Pressurized fluid generated, for example, by any conventional air compressor of the requisite rating, is admitted to the lower end of the piston-cylinder assembly 15 through a line 32 upon' opening of a control valve 33, so as to elevate the piston and carry the pad 18 into substantially the FIG. 2 position, wherein the pad is shown in sealing engagement with the bottom peripheral edge 19 of chamber wall 14. Obviously, the plate and pad 18 may be elevated by other means than the hydraulic means illustrated and described above.

A suitable negative pressure source such as a vacuum pump 34 is connected, as by conduit 35, in flow communication with the interior of chamber 24. When the pad 18 is engaged with the chamber wall as aforesaid, a valve 36 in said conduit 35 is opened so as to evacuate air from said chamber to about 29 in. mercury. This negative pressure is maintained for about two minutes during which time the polyurethane in the container boils and is degassed. The degassing can be observed through the transparent sheet 26. Implosion is avoided by providing escape ports 37 in pad 18.

At the expiration of the degassing operation, a diamine curing agent or catalyst, is introduced into the mass of polyurethane through a conduit 38 which includes a valve 39 and a downwardly turned discharge nozzle 41. In the present embodiment, a container of a predetermined quantity and mixture of the catalyst is connected with conduit 38 and when the valve 39 is opened, the negative pressure in chamber 24 permits free flow of the catalyst through conduit 38. As best shown in FIGS. 2 and 3, the discharge end of nozzle 41 is disposed closely adjacent to the upper one of the impellers 28 which are placed in operation simultaneously with opening of valve 39. As a result, the mass of polyurethane is disturbed by the impellers 28 while the catalyst is disbursed therein consequently, there is a uniform blending of the catalyst and polyurethane while under a pressure of about 15 in, of mercury. This blending requires about two minutes and when completed, the impeller motor 22 is shut OE and valve 39 is closed. The fluid to piston-cylinder assembly 15 is then cut off and the pad 18, and its floor plate 17, is returned to its lowered (FIG. 1) position and the container 31 of catalyzed degassed polyurethane is removed and immediately used.

One of the advantages arising from use of the present apparatus is that the exact catalyzing temperature is known at all times, it being indicated on gauge 29, and the chemical reaction is under constant surveillance as is also the vacuum pressure which is indicated on gauge 42., Although the machine disclosed may be of any size within the limits of workability, it is preferred that the chamber 24 be of a size to accommodate a container 31 havinga capacity'of approximately one gallon. As a consequence,

tory quality urethane on a production line basis when a plurality of apparatus of the character'herein disclosed are used in sequence.

Although. an exemplary embodiment of the invention has been illustrated in the accompanying drawings and described hereinabove, it is to be understood that the apparatus may vary in many respects from the disclosure and that the invention is to be limited by the spirit and scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United States is:

1. Apparatus for degassing and catalyzing a mass of polyurethane which comprises a firmly mounted upstanding open ended cylinder, a vertically adjustable closure for the bottom end of said cylinder, an open topped .container of polyurethane seated on said closure, means to raise the closure into tight sealing position against the open bottompf the cylinder to. locate the container in said cylinder, a movable closure for sealing the upper end immersed in the material in-the container, means connected with the interior of the cylinder effective to lower the atmospheric pressure in said cylinder sutficiently to degas said mass of polyurethane, and an inlet to admit a catalyst into said mass while it is disturbed by the impeller. 2. The apparatus recited in claim 1, in which a resilient sealing element is provided on the bottom end closure.

'3. The apparatus recited in claim 1, in which a resilient pad is arranged on the bottom end closure.

4. The apparatus recited in claim 1, in which a perforated resilient pad is arranged on the bottom end closure.

5. The apparatus recited in claim 4, in which the perforations are closed normally by the container.

6. The apparatus recited in claim 1, in which the upper end closure is transparent.

References Cited by the Examiner UNITED STATES PATENTS 3,098,640 7/1963 Rossman 259-122,

3,160,477 12/1964 Wasilewski 23 2s3 FOREIGN PATENTS 730,016 1/1943 Germany.

MORRIS O. WOLK, Primary Examiner.

JAMES H. TAYMAN, JR., Examiner.

Claims (1)

1. APPARATUS FOR DEGASSING AND CATALYZING A MASS OF POLYURETHANE WHICH COMPRISES A FIRMLY MOUNTED UPSTANDING OPEN ENDED CYLINDER, A VERTICALLY ADJUSTABLE CLOSURE FOR THE BOTTOM END OF SAID CYLINDER, AN OPEN TOPPED CONTAINER OF POLYURTHANE SEATED ON SAID CLOSURE, MEANS TO RAISE THE CLOSURE INTO TIGHT SEALING POSITION AGAINST THE OPEN BOTTOM OF THE CYLINDER TO LOCATE THE CONTAINER IN SAID CYLINDER, A MOVABLE CLOSURE FOR SEALING THE UPPER END OF SAID CYLINDER, AN IMPELLER ARRANGED IN SAID CYLINDER AND IMMERSED IN THE MATERIAL IN THE CONTAINER, MEANS CONNECTED WITH THE INTERIOR OF THE CYLINDER EFFECTIVE TO LOWER THE ATMOSPHERIC PRESSURE IN SAID CYLINDER SUFFICIENTLY TO DEGAS SAID MASS OF POLYURETHANE, AND AN INLET TO ADMIT A CATALYST INTO SAID MASS WHILE IT IS DISTURBED BY THE IMPELLER.

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