US4173608A — Process and apparatus for the manufacture of expa…

Claim 1

Independent Claim 120 words

A process for the pre-expansion of particles of thermoplastic resin material containing an inflating or expanding agent, said process comprising the steps of: continuously mixing small particles of said thermoplastic resin material with a polar liquid; continuously introducing said mixture into a resonant chamber communicating with a source of ultra-high frequency electro-magnetic or microwave energy; introducing said ultra-high frequency electro-magnetic microwave energy into said resonant chamber to vaporize said polar liquid on said plastic particles whereby said particles are caused to expand; introducing hot air into said chamber to pulse or agitate said vapor whereby condensation of said vapor on said pre-expanded particles is prevented and said particles are dried; and extracting said dried pre-expanded particles from said resonant chamber.

Claim 2

Dependent Claim 120 words

A process for the pre-expansion of particles of thermoplastic resin material containing an inflating or expanding agent, said process comprising the steps of: continuously mixing small particles of said thermoplastic resin material with a polar liquid; continuously introducing said mixture into a resonant chamber communicating with a source of ultra-high frequency electro-magnetic or microwave energy; introducing said ultra-high frequency electro-magnetic microwave energy into said resonant chamber to vaporize said polar liquid on said plastic particles whereby said particles are caused to expand; introducing hot air into said chamber to pulse or agitate said vapor whereby condensation of said vapor on said pre-expanded particles is prevented and said particles are dried; and extracting said dried pre-expanded particles from said resonant chamber.

Claim 3

Dependent Claim 29 words

Process of claim 1, wherein said polar liquid is composed of water and is introduced in the proporation of 10-40% of the weight of said particles to be pre-expanded.

Claim 4

Dependent Claim 24 words

Process of claim 1, wherein two wave polarizations are crossed so as to improve the distribution of ultra-high frequency energy in said resonant chamber.

Claim 5

Dependent Claim 28 words

Process of claim 1, wherein said resonant chamber is kept at a constant temperature, preferably between 70° C. and 100° C., during the entirety of said pre-expansion operation.

Claim 6

Dependent Claim 154 words

An installation for the manufacture of pre-expanded thermoplastic resin particles, said installation comprising: an insulated resonant chamber; a source of ultra-high frequency electromagnetic microwave energy; at least one waveguide for communicating said electromagnetic energy between said source and the base of said resonant chamber; a ferrite circulator connected between said source and each said waveguide; screw feed means communicating with said resonant chamber downstream of said wave guide and also communicating with a source of unexpanded particulate thermoplastic resin material; hot air blower means adapted to introduce air at a temperature of 50° C. to 100° C. into the base of said resonant chamber for agitating and drying said material; polar liquid pump means communicating with said screw means for moistening said unexpanded particulate thermoplastic resin material with a polar liquid prior to its introduction into said resonant chamber; and means at the upper extremity of said resonant chamber for extracting said pre-expanded particles.

Claim 7

Dependent Claim 154 words

An installation for the manufacture of pre-expanded thermoplastic resin particles, said installation comprising: an insulated resonant chamber; a source of ultra-high frequency electromagnetic microwave energy; at least one waveguide for communicating said electromagnetic energy between said source and the base of said resonant chamber; a ferrite circulator connected between said source and each said waveguide; screw feed means communicating with said resonant chamber downstream of said wave guide and also communicating with a source of unexpanded particulate thermoplastic resin material; hot air blower means adapted to introduce air at a temperature of 50° C. to 100° C. into the base of said resonant chamber for agitating and drying said material; polar liquid pump means communicating with said screw means for moistening said unexpanded particulate thermoplastic resin material with a polar liquid prior to its introduction into said resonant chamber; and means at the upper extremity of said resonant chamber for extracting said pre-expanded particles.

Claim 8

Dependent Claim 27 words

Installation of claim 5, wherein said ultra high frequency generator functions between 900 and 10,000 MHz and is of a strength of between 1 and 200 Kw.

Claim 9

Dependent Claim 51 words

Installation of claim 5, wherein said resonant chamber is truncated, with a circular cross-section, and is equipped with an agitator downstream of the screw feed means and has a grid at the upper extremity of said chamber and adapted to permit escape of the hot air and the evaporated polar liquid.

Claim 10

Dependent Claim 23 words

Installation of claim 5, wherein said installation comprises two waveguides offering a transverse-electric mode TE 01 and a transverse-magnetic mode TM 01 .

Claim 11

Dependent Claim 16 words

Installation of claim 5, wherein said pre-expanded particle extraction means is constituted by a depression system.

Claim 12

Dependent Claim 21 words

Installation of claim 7, wherein said pre-expanded particle extraction means is a mechanized extractor coupled to the axis of said agitator.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1982-11-05	1983-05-07	1983-11-06	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1986-11-05	1987-05-07	1987-11-06	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1990-11-05	1991-05-07	1991-11-06	$7700.00	Window Closed / Lapsed

Process and apparatus for the manufacture of expanded plastics materials

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