WO2003091642A1

WO2003091642A1 - Colling of extruded and compression molded materials

Info

Publication number: WO2003091642A1
Application number: PCT/US2003/012990
Authority: WO
Inventors: Herbert L. Hutchison; Jeffrey R. Brandt
Original assignee: Crane Plastics Company Llc
Priority date: 2002-04-24
Filing date: 2003-04-24
Publication date: 2003-11-06
Also published as: US20020174663A1; US6637213B2; AU2003231127A1

Abstract

The present invention relates to a system and a method for cooling extruded and molded materials. The present invention is especially useful to thoroughly cool an extrudate by directing a cooling fluid toward a surface of the extrudate (e.g., an interior surface that defines a hollow portion of an extrudate). Hollows may be created in order to reduce material, weight, and/or processing time. A cooling fluid is diverted toward the surface of the extrudate so as to cool the material and assist in solidification. A baffle may serve to divert the cooling fluid in the desired direction. Increases in production line throughput may result by rapidly cooling the molded material. In addition, the more efficient cooling may be achieved with a lesser amount of the cooling fluid, and the velocity and temperature of the cooling fluid may be reduced. Other uses for the present invention include injection molding, compression molding, gas assist molding, and co-extrusion.

Description

COOLING OF EXTRUDED AND COMPRESSION MOLDED MATERIALS

This is a continuation-in-part of U.S. Application No. 10/025,432, filed

December 19, 2001 , which is a continuation-in-part of U.S. Application No.

09/766,054, filed January 19, 2001, each of which is hereby incorporated by

reference in its entirety.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates generally to a system and method for cooling

manufactured articles and, more particularly, to a system and method for cooling

extruded and molded materials with a fluid that is below about 80 degrees Fahrenheit. The present invention may also be used in other types of manufacturing

techniques in which the output or material must be cooled from a heated state. The present invention includes a system and method for cooling synthetic wood composite materials including, but not limited to, cellulosic-filled plastic composites.

In addition, the present invention may also be used to cool other types of pure or mixed materials including, but not limited to, plastics, polymers, foamed plastics,

plastic compositions, inorganic-filled plastic compositions, metals, metallic compositions, alloys, mixtures including any of the aforementioned materials, and

other similar, conventional, or suitable materials that need to be cooled after being

processed. For instance, the present invention may be used to cool polyvinyl

chloride (PVC) products and products made from other plastics.

For several reasons, there is a need to find materials that exhibit the look and

feel of natural wood. The supply of wood in the world's forests for construction and

other purposes is dwindling. Consequently, the supply of wood from mature trees has become a concern in recent years, and the cost of wood has risen. As a result,

several attempts have been made by others to find a suitable wood-like material.

Cellulosic/polymer composites have been developed as replacements for all-

natural wood, particle board, wafer board, and other similar materials. For example,

U.S. Patent Nos. 3,908,902, 4,091 ,153, 4,686,251 , 4,708,623, 5,002,713,

5,055,247, 5,087,400, 5,151,238, 6,011 ,091 , and 6,103,791 relate to processes

and/or compositions for making wood replacement products. As compared to

natural woods, cellulosic/polymer composites offer superior resistance to wear and

tear. In addition, cellulosic/polymer composites have enhanced resistance to moisture, and it is well known that the retention of moisture is a primary cause of the

warping, splintering, and discoloration of natural woods. Moreover, cellulosic/polymer composites may be sawed, sanded, shaped, turned, fastened, and finished in the same manner as natural woods. Therefore, cellulosic/polymer

composites are commonly used for applications such as interior and exterior decorative house moldings, picture frames, furniture, porch decks, deck railings, window moldings, window components, door components, roofing structures,

building siding, and other suitable indoor and outdoor items. However, many

attempts to make products from cellulosic/polymer composite materials have failed

due to poor or improper manufacturing techniques. In the present invention, a product or article is manufactured by a desired

technique such as, but not limited to, extrusion, compression molding, injection

molding, or other similar, suitable, or conventional manufacturing techniques. The

product is then cooled by subjecting it to a cooling fluid. The present invention can

be used alone or in conjunction with other known or later developed cooling methods. Accordingly, the present invention can more thoroughly and efficiently

cool the manufactured product or article to a desired level. This can lead to faster

production times as well as a product having improved structural, physical, and

aesthetic characteristics.

In addition to the novel features and advantages mentioned above, other

objects and advantages of the present invention will be readily apparent from the

following descriptions of the drawings and exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross sectional view of an extrudate.

Figure 2 is a view of an extrusion die showing an exemplary location of a

cryogenic nozzle.

Figure 3 is an elevation view of one embodiment of a system implementing

the present invention.

Figure 4 is a partial cross sectional view along the line A-A of Figure 3.

Figure 5 is a partial elevation view of another embodiment of a system of the

present invention.

Figure 6 shows a sectioned schematic of an extruder line used in accordance

with the practice of one embodiment of the present invention.

Figure 7 is a cross sectional view from a lateral side angle of an exemplary

die of the present invention.

Figure 8 is a cross sectional view from a top side angle of the die of Figure 7.

Figure 9 is a cross sectional view from an exit side angle of the die of Figure

7. Figure 10 is a cross sectional view from a lateral side angle of an exemplary

die of the present invention that includes a baffle.

Figure 11 is a cross sectional view from a lateral side angle of another

exemplary die of the present invention that includes a baffle.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT S)

The present invention is directed to a system and method for cooling

manufactured articles or products. It is not intended to limit the present invention to particular manufacturing techniques or particular materials. The present invention

may be used to cool articles or products made by variety of different manufacturing

techniques. Examples of manufacturing techniques that may utilize the present invention include, but are not limited to, extrusion (including co-extrusion),

compression molding, injection molding, and other known, similar, or conventional techniques for manufacturing products or articles from plastic, wood, metal, mixtures of these materials, or other materials used to make products.

The present invention is particularly useful for cooling plastics, polymers, and cellulosic/polymer composite materials that have been extruded or molded. The

materials that may be used to make cellulosic/polymer composites include, but are not limited to, cellulosic fillers, polymers, plastics, thermoplastics, inorganic fillers,

cross-linking agents, lubricants, process aids, stabilizers, accelerators, inhibitors, enhancers, compatibilizers, blowing agents, foaming agents, thermosetting

materials, and other similar, suitable, or conventional materials. Examples of

cellulosic fillers include sawdust, newspapers, alfalfa, wheat pulp, wood chips, wood fibers, wood particles, ground wood, wood flour, wood flakes, wood veneers, wood

laminates, paper, cardboard, straw, cotton, rice hulls, coconut shells, peanut shells, bagass, plant fibers, bamboo fiber, palm fiber, kenaf, flax, and other similar

materials. In addition to PVC, examples of polymers include multilayer films, high

density polyethylene (HDPE), polypropylene (PP), low density polyethylene (LDPE),

chlorinated polyvinyl chloride (CPVC), acrylonitrile butadiene styrene (ABS), ethyl-

vinyl acetate, other similar copolymers, other similar, suitable, or conventional

thermoplastic materials, and formulations that incorporate any of the aforementioned

polymers. Examples of inorganic fillers include talc, calcium carbonate, kaolin clay,

magnesium oxide, titanium dioxide, silica, mica, barium sulfate, acrylics, and other similar, suitable, or conventional materials. Examples of thermosetting materials

include polyurethanes, such as isocyanates, phenolic resins, unsaturated polyesters,

epoxy resins, and other similar, suitable, or conventional materials. Combinations of the aforementioned materials are also examples of thermosetting materials. Examples of lubricants include zinc stearate, calcium stearate, esters, amide wax,

paraffin wax, ethylene bis-stearamide, and other similar, suitable, or conventional materials. Examples of stabilizers include tin stabilizers, lead and metal soaps such as barium, cadmium, and zinc, and other similar, suitable, or conventional materials.

In addition, examples of process aids include acrylic modifiers and other similar,

suitable, or conventional materials.

Figure 1 shows one example of an extrudate 100 that may be cooled by the

present invention. The extrudate 100 includes an exterior surface 102, a hollow

104, an interior surface 106, and two ends 108. The exterior surface 102 may be

cooled by a traditional method such as using a warm water bath or water mist.

However, the interior surface 106 may not be sufficiently cooled by many traditional

methods because the surface may not be available for contact with the cooling medium. The interior surface 106 defines the boundary of the hollow 104. The

interior surface 106 may be accessed from either end 108. The interior surface 106

may not be cooled to a desired level within a desired amount of time by externally

applied coolants.

Figure 2 shows one example of an extrusion die 200 adapted with the present

invention. The extrusion die 200 defines the cross section of the extrudate by the shape of the profile form/flow channel 206. Hollows in the cross section of the

extrudate are each formed with a standing core 202. The standing core 202 is fitted

with a nozzle 204. The nozzle 204 is adapted to connect with a source of the cooling fluid (not shown). The nozzle 204 is oriented to spray into the hollow formed

in the extrudate cross section by the standing core 202.

Figure 3 shows one example of a system 300 that may utilize the present

invention. The system 300 includes an extruder 302 and an extruder 304. In this example, a crosshead die 306 puts a cap layer from the extruder 304 on the material extruded by the extruder 302. A container 308 may be used to hold a cooling fluid of

the present invention. The fluid is used to cool the extruded product or article 312 after it exits the die 306. In this embodiment, a valve is used to control the release

of gas, e.g., vapor, from the fluid. A hose, conduit, tube, or any other suitable

transfer device 310 may be used to direct the gas from the container 308 to the

desired location for cooling the extruded product 312. The transfer device 310 may

be formed by one integral component or a plurality of interconnected components.

For instance, a portion of the transfer device 310 may be a passage through the die

306. In this example, the transfer device 310 extends through the die 306 so that

the gas is released in the hollow of the extruded product 312 after it exits the die 306. In this manner, the present invention can provide efficient and thorough

cooling of the extruded product 312. Moreover, the extruded product 312 may be

further introduced into a liquid bath 314, a spray mist chamber 316, and/or any other

desired cooling system to achieve additional cooling of the extruded product 312 if

desired. Examples of the liquid bath 314 and the spray mist chamber 316 are

provided in U.S. Patent No. 5,827,462.

Depending on the type of cooling fluid and the desired expulsion rate of the

cooling fluid, the container 308 may be pressurized. The container 308 may be

connected to a compressor, e.g., an air compressor or any other similar, suitable, or conventional compressing device, in order to maintain the desired pressure in the

container 308. Additionally, the container 308 may be in fluid communication with a blower or a pump to obtain the desired expulsion rate of the cooling fluid from the container 308. A blower in fluid communication with the container 308 may also be

utilized to accelerate the cooling fluid to a desired velocity after it has been expelled. Figure 4 is a cross section view along the line A-A of Figure 3. The extruded

product 312 includes a cap layer 404. The transfer device 310 may extend through the die 306 to a nozzle 406 that releases gas from the cooling fluid into a hollow of

the extruded product 312. In this instance, gas vapor 402 permeates through the

hollow of the extruded product 312, thereby providing much improved cooling of the

extruded product 312. In fact, the inventors have surprisingly discovered that using

the present invention to inject the cooling fluid into a hollow portion of a product may be sufficient to thoroughly cool the entire product, i.e., the inside and the outside of

the product. As a result, the present invention may eliminate the need to provide

another cooling system to cool the outer surface of the product. It should be recognized that Figures 3 and 4 are merely one example of a

manufacturing system that may utilize the present invention. As noted above, the

present invention may be used in any manufacturing system in which the processed

material needs to be cooled to a desired level. For example, the present invention

may be used in an extrusion system consisting of a single extruder that is in-line with

a die. Also, the present invention may be used to cool any type of material

including, but not limited to, injection molded materials and compression molded

materials.

It should also be recognized that the cooling fluid of the present invention

may be expelled elsewhere relative to the manufactured product (i.e., other than in a

hollow portion of the product). For example, Figure 5 shows an embodiment in

which the gas vapor 500 is dispersed by the transfer device 502 onto the exterior of

the product 504. The present invention also includes dispersing multiple streams of

the cooling fluid onto the same or different portions of the manufactured product.

For instance, flows of the cooling fluid may be simultaneously dispersed onto the

exterior and interior surfaces of the manufactured product.

Turning to Figure 6, this Figure shows a sectioned schematic of an extruder

line 600 used in accordance with the practice of one embodiment of the present

invention. Figure 6 shows an extruder line 600 which includes co-extrusion

apparatus 602. Co-extrusion apparatus 602 includes insulated transport tube 604

that is adapted to carry cooling fluid 606. The cooling fluid 606 may be gas that may

be delivered from a supply of cryogenic fluid. Co-extrusion apparatus 602 also

includes a cross head extruder 608 which is adapted to prepare the thermoplastic

material 610 for extrusion through a die which forms a hollow, rectangular profile and urges it along longitudinal direction 612. Further layers of thermoplastic material

such as layer 614 may be added through the use of additional extruders such as

extruder 616. Such additional layers of thermoplastic material may include layers of

material with specific characteristics for exterior use, such as fluoropolymers and

PVC having greater or lesser durability and resistance to changes in aesthetic

appearance resulting from exposure to weather and environmental/atmospheric

conditions, as dictated by the desired end user. The thermoplastic material 610 is

formed by the forming die 618 into the desired final shape, such as a rectangular

cross-section. The cooling fluid 606 permeates through the hollow space created in thermoplastic material 610. The cooling fluid 606 may be at a significantly lower

temperature than the surrounding thermoplastic material 610. The cooling fluid 606 cools the thermoplastic material 610, assisting the thermoplastic material to "skin" or

solidify.

Figures 7 through 9 show a cross sectional view of one example of a die 700 that is configured to be in-line with an extruder. The extruded material flows through the die in the direction indicated by arrow 702. In this example, the resultant

extrudate 704 defines three hollow portions that are separated by webs 706 and 708. The cooling fluid enters the die 700 through passages 710. In some

embodiments, it should be recognized that a tube, conduit, or any other type of transfer device may extend through the passages 710 for directing the flow of the

cooling fluid through the passages 710. The cooling fluid exits the die 700 through

passages 710 in the direction indicated by arrows 712. In such an embodiment, the

passages 710 intersect the path of flow of the extruded material through the die 700.

In other words, the passages 710 intersect the flow channel in the die 700. The die 700 may be heated to a sufficient level to facilitate extrusion and limit

premature curing of the extrudate in the die 700. In this example of an in-line

system, the passages 710 actually extend through the die 700, intersecting the path

of flow of the extruded material through the die 700. In such embodiments, it may

be preferable to limit cooling of the die 700 by the cooling fluid in the passages 710.

Accordingly, the passages 710 may be insulated by a suitable material. For example, the passages 710 may be lined with ceramic insulation, putty ceramics, or

any other similar, suitable, or conventional insulating material in order to limit

undesired heat loss by the die 700. In fact, it should be recognized that the transfer

device for the cooling fluid in any type of embodiment may be insulated in order to limit undesired cooling of surrounding items.

As best seen in the example of Figure 9, the passages 710 may be

substantially surrounded by die material 714 even where the passages 710 intersect the path of flow of the extruded material. In this manner, direct contact between the extruded material and the passages 710 may be avoided, if desired. The die

material 714 surrounding the passages 710 may be heated to facilitate the extrusion process. Also, air gaps may be provided between the die material 714 and the

passages 710 for additional insulation.

Any desired cooling fluid may be used in the present invention. In one exemplary embodiment, the cooling fluid, e.g., gas or liquid, may have a temperature

below about 80 degrees Fahrenheit, more preferably below about 68 degrees

Fahrenheit, still more preferably below about 32 degrees Fahrenheit, even more preferably below about minus 100 degrees Fahrenheit. On the other hand, the

temperature may be above about minus 325 degrees Fahrenheit, more preferably above about minus 300 degrees Fahrenheit, still more preferably above about minus

275 degrees Fahrenheit, even more preferably above about minus 250 degrees

Fahrenheit. However, in some embodiments of the present invention, the cooling

fluid may be above about 80 degrees Fahrenheit or below about minus 325 degrees

Fahrenheit. Examples of the cooling fluid are air and water. Another example of the

cooling fluid is gas or vapor that is produced from a cryogenic fluid. For instance, a

cryogenic fluid may have a temperature below about minus 250 degrees Fahrenheit.

Examples of cryogenic fluids include, but are not limited to, liquid oxygen, liquid

nitrogen, liquid neon, liquid hydrogen, liquid helium, and other similar, suitable, or

conventional cryogenic fluids.

In addition to the temperature, the velocity of the cooling fluid may also impact

its effectiveness. By selecting a suitable velocity and temperature of the cooling fluid, the inventors have discovered that an entire product can be thoroughly cooled just by injecting the cooling fluid into a hollow portion of the product. The velocity of the cooling fluid may be greater than about 10 miles per hour, more preferably

greater than about 40 miles per hour, and it may be less than about 100 miles per

hour, more preferably less than about 50 miles per hour. However, it should be recognized that the velocity of the cooling fluid may be less than about 10 miles per

hour or greater than about 100 miles per hour in some embodiments.

The efficiency of the present invention may be further increased by diverting

the flow of the cooling fluid toward the surface of the extruded product as it exits the

die. By concentrating the cooling fluid on a surface of the extrudate, the desired amount of cooling may occur more quickly resulting in the use of less cooling fluid as

compared to non-diversion methods. Moreover, the increased cooling efficiency enables the use of warmer cooling fluids and a reduction in the velocity of the

cooling fluid as compared to non-diversion methods. For example, this embodiment

of the present invention may be particularly useful if it is desired to use a cooling

fluid that is warmer than about 80 degrees Fahrenheit. However, it should be

recognized that, in many embodiments, it may be desirable to use a cooling fluid

below about 80 degrees Fahrenheit for optimal cooling efficiency.

Figure 10 shows one example of a die that is adapted to divert a cooling fluid

toward a surface of an extruded project. The die 800 of this embodiment may

include any of the optional or preferred features of the die 700 shown in Figures 7 through 9. The cooling fluid may enter the die 800 through a passage 810. A baffle

820 is in fluid communication with the passage 810 such it receives the cooling fluid. The baffle 820 is adapted to then divert the flow of the cooling fluid such that it is

directed to a desired surface of the extrudate. By directing the cooling fluid toward a surface of the extrudate, the baffle 820 may also create a more turbulent flow of the cooling fluid (as compared to a straight line flow that is not directed toward a surface

of the extrudate) which further enhances the efficiency of the cooling process. The baffle 820 may be any device or structure that is suitable for diverting the flow of the

cooling fluid to the desired location (e.g., an interior or exterior surface of a product).

In this particular example, the baffle 820 is adapted to divert the cooling fluid in the

direction of arrows 830 toward an interior surface of a hollow portion of the

extrudate. For this purpose, the baffle 820 includes an inner conical portion 840 that forces the cooling fluid in the direction of arrows 830.

Figure 10 shows one example of a design of a baffle 820. It should be

recognized that the design of a baffle of the present invention may vary so as to divert the cooling fluid in the desired direction. Of course, the desired direction will

vary according to the type of product being extruded and the location of the baffle

relative to the extruded product.

The baffle 820 may be placed in fluid communication with the passage 810 in

any suitable manner. In the example of Figure 10, the baffle 820 is secured to an

end portion of a conduit 850 that extends through the passage 810. The baffle 820

may be secured to the end portion of the conduit 850 in any desired manner. For

example, the baffle 820 may be threaded, i.e., screwed, onto the end portion of the

conduit 850. For other examples, the baffle 820 may be secured to the conduit 850

using other mechanical means (e.g., screws, pins, and other types of mechanical

fastening devices) and/or adhesives. As previously noted, the conduit 850 may be

insulated. The baffle 820 may also be insulated, if desired. The baffle 820 is offset

from the heated portion 860 of the die 800 in this particular example. Optionally,

there may be an insulated layer 870 on an exit end of the die 800. The insulated

layer 870 may be useful to prevent the cooling fluid from cooling the heated portion

860 of the die 800.

Figure 11 shows another example of a die which may include any of the

optional or preferred features of the other embodiments of the present invention. In

this embodiment, the die 900 includes a passage 910 that is in fluid communication

with the baffle 920. The baffle 920 is not offset from the heated portion 930 of the

die 900 in this example. In order to limit undesired cooling of the heated portion

930, it may be preferred to use an insulated baffle 920 or otherwise provide a layer

of insulation between the baffle 920 and the heated portion 930. As in the previous

example, the baffle 920 may be connected to a conduit 940 that lines that passage 910. It should also be recognized that the baffle 920 may be placed in fluid

communication with the passage 910 in any other suitable manner. For example,

the baffle 920 may have a threaded connection with the heated portion 930. In other

examples, the baffle 920 may be connected to the heated portion 930 using other

mechanical means (e.g., screws, pins, and other types of mechanical fastening

devices) and/or adhesives. As in the previous example, an exit end of the die 900 may include a layer of insulation 950.

The exemplary embodiments herein disclosed are not intended to be

exhaustive or to unnecessarily limit the scope of the invention. The exemplary

embodiments were chosen and described in order to explain the principles of the present invention so that others skilled in the art may practice the invention. Having shown and described exemplary embodiments of the present invention, those skilled

in the art will realize that many variations and modifications may be made to affect the described invention. Many of those variations and modifications will provide the

same result and fall within the spirit of the claimed invention. It is the intention, therefore, to limit the invention only as indicated by the scope of the claims.

Claims

WHAT IS CLAIMED IS:

1. A method for cooling a product, said method comprising:

providing a die, said die having a passage;

extruding a material through said die to form said product, said product

having a surface;

directing a cooling fluid through said passage; and

diverting said cooling fluid such that said cooling fluid is directed toward said

surface of said product.

2. The method of claim 1 wherein said passage is lined with an insulating

material.

3. The method of claim 2 wherein said insulating material is selected from the

group consisting of ceramic insulation and putty ceramics.

4. The method of claim 1 wherein said material is selected from the group

consisting of plastics, metals, cellulosic/polymer compositions, inorganic-filled plastic

compositions, and foamed plastics.

5. The method of claim 1 wherein said cooling fluid has a temperature between about 80 degrees Fahrenheit and about minus 325 degrees Fahrenheit.

6. The method of claim 5 wherein said cooling fluid has a temperature between

about 68 degrees Fahrenheit and about minus 300 degrees Fahrenheit.

7. The method of claim 6 wherein said cooling fluid has a temperature between about 32 degrees Fahrenheit and about minus 275 degrees Fahrenheit.

8. The method of claim 7 wherein said cooling fluid has a temperature between

about minus 100 degrees Fahrenheit and about minus 250 degrees Fahrenheit.

9. The method of claim 1 wherein said cooling fluid is selected from liquid

oxygen, liquid nitrogen, liquid neon, liquid hydrogen, liquid helium, and air.

10. The method of claim 1 wherein said cooling fluid is selected from the group

selected from liquids, gases, and vapors.

11. The method of claim 1 wherein said die is in-line with an extruder.

12. The method of claim 11 wherein said passage intersects a path of flow of said

material through said die.

13. The method of claim 1 wherein said surface is an interior surface that defines

a hollow portion of said product.

14. The method of claim 1 wherein said surface is an exterior surface of said

product.

15. A die adapted to be used with an extruder to form a product, said die

comprising:

a flow channel adapted to be in fluid communication with said extruder such

that an extruded material is forced through said flow channel to form said product;

a passage extending through said die, said passage adapted to be in fluid

communication with a source of a cooling fluid; and

a baffle in fluid communication with said passage, said baffle adapted to

divert said cooling fluid toward a surface of said product as said product exits said

die.

16. The die of claim 15 wherein said passage is lined with an insulating material.

17. The die of claim 16 wherein said insulating material is selected from the group

consisting of ceramic insulation and putty ceramics.

18. The die of claim 15 wherein said die is adapted to be in-line with said

extruder.

19. The die of claim 15 wherein said baffle is situated relative to said flow channel

such that said baffle is adapted to divert said cooling fluid toward said surface which

is an interior surface that defines a hollow portion of said product.

20. The die of claim 15 wherein said baffle is situated relative to said flow channel

is an exterior surface of said product.

21. The die of claim 15 wherein said baffle has an inner conical portion adapted to divert said cooling fluid toward said surface of said product.

22. The die of claim 15 further comprising a layer of insulating material on an exit end of said die.

23. A die adapted to be used with an extruder to form a product having an interior

surface that defines a hollow portion, said die comprising: a flow channel adapted to be in fluid communication with said extruder such

that an extruded material is forced through said flow channel to form said product; a passage extending through said die and intersecting said flow channel, said

passage adapted to be in fluid communication with a source of a cooling fluid; and

a baffle in fluid communication with said passage, said baffle adapted to divert said cooling fluid toward said interior surface of said product as said product

exits said die.

24. The die of claim 23 wherein said passage is lined with an insulating material.

25. The die of claim 24 wherein said insulating material is selected from the group

consisting of ceramic insulation and putty ceramics.

26. The die of claim 23 wherein said die is adapted to be in-line with said

extruder.

27. The die of claim 23 wherein said baffle has an inner conical portion adapted

to divert said cooling fluid toward said interior surface of said product.

28. The die of claim 23 further comprising a layer of insulating material on an exit

end of said die.