US4039609A — Method for the manufacture of thin-walled shaped …

Claim 1

Independent Claim 140 words

A method of manufacturing thin-walled synthetic plastic articles which comprises the sequential steps of (2) extruding a continuous web of hot thermoplastic material at a relatively high temperature in the upper limits of the range wherein said material is in substantially fluid but extrudable plastic condition, (2) substantially immediately rapidly precooling the opposite surfaces of said web to form along said surfaces thin supportive layers having a temperature in the range wherein said material is substantially solid and not elastically deformable while the hotter core material between said layers remains in substantially fluid condition, (3) allowing said layers to be partially reheated by heat conducted from the core whereby the temperature at said layers is such that the material is said layers achieves an elastically deformable condition, and (4) then thermally forming said web to an article of desired shape.

Claim 2

Independent Claim 140 words

A method of manufacturing thin-walled synthetic plastic articles which comprises the sequential steps of (2) extruding a continuous web of hot thermoplastic material at a relatively high temperature in the upper limits of the range wherein said material is in substantially fluid but extrudable plastic condition, (2) substantially immediately rapidly precooling the opposite surfaces of said web to form along said surfaces thin supportive layers having a temperature in the range wherein said material is substantially solid and not elastically deformable while the hotter core material between said layers remains in substantially fluid condition, (3) allowing said layers to be partially reheated by heat conducted from the core whereby the temperature at said layers is such that the material is said layers achieves an elastically deformable condition, and (4) then thermally forming said web to an article of desired shape.

Claim 3

Dependent Claim 57 words

The method defined in claim 1, wherein the web is subjected to a forming tool operation wherein the respective layers are deformed and or displaced relatively according to one or more shaped tool surfaces acting thereon and the still hot fluid core material distributes itself in accord with tool pressures to occupy the space between said layers.

Claim 4

Independent Claim 163 words

A method of manufacturing thin-walled synthetic plastic articles which comprises the sequential steps of extruding a continuous hot plastic web of thermoplastic material at a temperature wherein said material is in substantially fluid condition and substantially immediately stabilizing said web by passing the opposite surfaces of said web in contact with heat exchange areas maintained at substantially constant cooling temperature materially below the extrusion temperature and below the temperature range in which said material is elastically deformable for precooling opposite surfaces of the web to provide therealong continuous relatively thin outer supportive layers while the core remains in hot fluid condition, allowing said outer layers to be partially reheated by heat conducted from the core so that said layers become sufficiently elastic and deformable to permit shaping, and subsequently subjecting said web to a shaping tool operation wherein said layers are positively displaced relative to each other while the hot plastic material between said layers remain sufficiently fluid for redistribution between said layers.

Claim 5

Independent Claim 163 words

A method of manufacturing thin-walled synthetic plastic articles which comprises the sequential steps of extruding a continuous hot plastic web of thermoplastic material at a temperature wherein said material is in substantially fluid condition and substantially immediately stabilizing said web by passing the opposite surfaces of said web in contact with heat exchange areas maintained at substantially constant cooling temperature materially below the extrusion temperature and below the temperature range in which said material is elastically deformable for precooling opposite surfaces of the web to provide therealong continuous relatively thin outer supportive layers while the core remains in hot fluid condition, allowing said outer layers to be partially reheated by heat conducted from the core so that said layers become sufficiently elastic and deformable to permit shaping, and subsequently subjecting said web to a shaping tool operation wherein said layers are positively displaced relative to each other while the hot plastic material between said layers remain sufficiently fluid for redistribution between said layers.

Claim 6

Dependent Claim 36 words

The method defined in claim 3, wherein during said shaping tool operation said layers are shaped substantially by stretching and at least one of the layers is further cooled by contact with a shaping tool surface.

Claim 7

Dependent Claim 37 words

The method defined in claim 3 wherein during said shaping tool operation corresponding opposite portions of said outer web layers are relatively displaced substantially in their respective planes, as permitted by the relatively fluid plastic material therebetween.

Claim 8

Dependent Claim 22 words

The method defined in claim 3 wherein the hot plastic material between said layers remains at substantially extrusion temperature during web stabilization.

Claim 9

Dependent Claim 62 words

The method defined in claim 3 wherein the material is polystyrene, the extrusion temperatures are in the range of 200°-220° C, and the web entering the shaping tool operation has a core temperature in the range of 140°-170° C and an outer layer temperature in the range of 115°-140° C, a minimum difference of about 25° C being maintained within the range.

Claim 10

Dependent Claim 71 words

The method defined in claim 3, wherein the material is substantially equal parts of polyestyrene and high impact polystyrol, the extrusion temperatures are in the range of 200°14 220° C, and the web entering the shaping tool operation has a core temperature in the range of 140°-170° C and an outer layer temperature in the range of 115°-140° C, a minimum difference of about 25° C being maintained within the range.

Claim 11

Dependent Claim 24 words

The method defined in claim 3, wherein temperature distribution during reheating is effected by proportional reflection of radiant heat from the hot plastic web.

Claim 12

Dependent Claim 26 words

The method defined in claim 3, wherein air at controlled temperature is circulated over the layer surfaces at said areas for effecting temperature distribution during reheating.

Claim 13

Dependent Claim 17 words

The method defined in claim 3, wherein said web consists essentially of a single extruded web component.

Claim 14

Dependent Claim 43 words

The method defined in claim 3, wherein said web is a composite that consists essentially of at least two extruded web components of thermoplastic material superposed in the hot plastic state, and said supportive layers are formed on the two outermost surfaces thereof.

Claim 15

Dependent Claim 50 words

The method defined in claim 12, wherein said composite web is formed by superposing hot plastic web components of a first material upon opposite sides of a hot plastic web component of a core material, and said supportive layers are formed on the outer surfaces of said first material components.

Claim 16

Dependent Claim 20 words

The method defined in claim 12, wherein said composite web is formed of extruded web components of different thermoplastic materials.

Claim 17

Dependent Claim 28 words

The method defined in claim 12, wherein one of said web components is a standard polystyrene and a superposed component is an impact resistant polystyrene reacted with butadiene-rubber.

Claim 18

Dependent Claim 34 words

The method defined in claim 15, wherein said web components are extruded at temperatures of about 170°-1/2° C and said surface layers are cooled to a temperature within the range of about 130°-140° C.

Claim 19

Dependent Claim 41 words

The method defined in claim 14, characterized in that the thermoplastic material of one web component is polystyrene or polystyrene reacted with butadiene-rubber, and that the thermoplastic material of the other web component is a polyolefin, for example polypropylene or polyethylene.

Claim 20

Dependent Claim 38 words

The method defined in claim 14, characterized in that the thermoplastic material of one web component is a polystyrene or a polystyrene reacted with butadiene-rubber and that the thermoplastic material of the other web component is a polycarbonate.

Claim 21

Dependent Claim 32 words

The method defined in claim 13, characterized in that the thermoplastic material of the core component is polyalpha-methyl-styrene while the outer web components are of polystyrene or a polystyrene reacted with butadiene-rubber.

Claim 22

Dependent Claim 30 words

A method as defined in claim 3, including the step of precooling the stabilized web prior to the shaping operation outside the areas that are to be shaped into articles.

Claim 23

Dependent Claim 27 words

A method as defined in claim 20, wherein the web is intermittently advanced to subject sections of predetermined length successively to precooling and shaping operations in snychronism.

Claim 24

Dependent Claim 28 words

The method defined in claim 21, wherein said precooled web is intermittently advanced to subject each said web section to two successive stages of precooling prior to shaping.

Claim 25

Dependent Claim 32 words

A method as defined in claim 22 wherein in each succeeding precooling stage, smaller areas move closely approximating the areas to those to be formed into articles are not subjected to precooling.

Claim 26

Dependent Claim 31 words

A method as defined in claim 20, characterized in that precooling is sufficient to provide a framelike stiffening structure in those parts of the web not to be shaped into articles.

Claim 27

Dependent Claim 70 words

A method as defined in claim 3, wherein (a) the stabilized web at the shaping temperature is passed through a thermal forming station in an essentially vertical direction and the shaped articles are formed out of the web in an essentially horizontal direction; and (b) the shaped articles are separated from the web simultaneously with thermal shaping and are cooled further for a predetermined period after separation from the web.

Claim 28

Dependent Claim 21 words

A method as defined in claim 25, characterized in that the web is intermittently moved longitudinally downwardly through the forming station.

Claim 29

Dependent Claim 27 words

A method as defined in claim 25, characterized in that the web is precooled in the areas outside those to be shaped and prior to thermal forming.

Claim 30

Dependent Claim 19 words

A method as defined in claim 25, characterized in that the shaped articles are post-cooled in cooled shaping tools.

Claim 31

Independent Claim 174 words

A method of manufacturing thin-walled synthetic plastic articles which comprises the sequential steps of forming as by extrusion a continuous hot plastic web of substantially fluid thermoplastic material and substantially immediately stabilizing said web by contacting opposite surfaces of the web with heat exchange surfaces maintained at a predetermined cooling temperature appreciably lower than the forming temperature to initially provide along the said web continuous cooled outer supportive layers that are not sufficiently deformable to permit their shaping in a subsequent shaping tool operation while the hot plastic material between said layers remains as a fluid core heated close to the extrusion temperature at forming; heating said layers to elastically deformable condition by heat derived from said core; and during said shaping tool operation displacing and stretching said layers relative to each other, and further cooling at least one of said layers by contact with a cooled shaping tool surface that corresponds with a desired end product; said fluid core being distributed between said two opposite shell-like outer surfaces in response to shaping pressure.

Claim 32

Independent Claim 174 words

A method of manufacturing thin-walled synthetic plastic articles which comprises the sequential steps of forming as by extrusion a continuous hot plastic web of substantially fluid thermoplastic material and substantially immediately stabilizing said web by contacting opposite surfaces of the web with heat exchange surfaces maintained at a predetermined cooling temperature appreciably lower than the forming temperature to initially provide along the said web continuous cooled outer supportive layers that are not sufficiently deformable to permit their shaping in a subsequent shaping tool operation while the hot plastic material between said layers remains as a fluid core heated close to the extrusion temperature at forming; heating said layers to elastically deformable condition by heat derived from said core; and during said shaping tool operation displacing and stretching said layers relative to each other, and further cooling at least one of said layers by contact with a cooled shaping tool surface that corresponds with a desired end product; said fluid core being distributed between said two opposite shell-like outer surfaces in response to shaping pressure.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1980-08-01	1981-01-31	1981-08-02	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1984-08-01	1985-01-31	1985-08-02	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1988-08-01	1989-01-31	1989-08-02	$7700.00	Window Closed / Lapsed

Method for the manufacture of thin-walled shaped articles of thermoplastic material

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