US4806294A — Method of making a foam injection molded article

Claim 1

Independent Claim 128 words

A method of making a foam injection molded article, said method comprising the steps of: dispersing into a polymer resin (a) an effective amount of a primary chemical blowing agent comprising sodium borohydride and (b) an activation system comprising a first mixture of effective amounts of sodium bicarbonate and citric acid, to form a second mixture of said resin, primary chemical blowing agent and activation system, said sodium borohydride and said activation system being isolated from direct contact with each other until gas production is desired; heating said second mixture whereby said activation system releases water and said sodium borohydride reacts with said water to produce hydrogen gas; and subsequently injecting said second mixture into a mold obtaining expansion of said polymer resin into a molded foam article.

Claim 2

Independent Claim 128 words

A method of making a foam injection molded article, said method comprising the steps of: dispersing into a polymer resin (a) an effective amount of a primary chemical blowing agent comprising sodium borohydride and (b) an activation system comprising a first mixture of effective amounts of sodium bicarbonate and citric acid, to form a second mixture of said resin, primary chemical blowing agent and activation system, said sodium borohydride and said activation system being isolated from direct contact with each other until gas production is desired; heating said second mixture whereby said activation system releases water and said sodium borohydride reacts with said water to produce hydrogen gas; and subsequently injecting said second mixture into a mold obtaining expansion of said polymer resin into a molded foam article.

Claim 3

Dependent Claim 21 words

The method of claim 1 wherein said first mixture comprises an approximately equimolar mixture of said citric acid and sodium bicarbonate.

Claim 4

Dependent Claim 28 words

The method of claim 1 wherein no more than about 8 parts by weight of said first mixture are present per part by weight of said sodium borohydride.

Claim 5

Dependent Claim 25 words

The method of claim 3 wherein about 5 parts by weight of said first mixture are present per part by weight of said sodium borohydride.

Claim 6

Dependent Claim 18 words

The method of claim 1 wherein said sodium borohydride comprises about 0.01-5 wt % of said second mixture.

Claim 7

Dependent Claim 23 words

The method of claim 5 wherein said sodium borohydride dispersed in said polymer resin comprises about 0.1-0.3 wt % of said second mixture.

Claim 8

Dependent Claim 23 words

The method of claim 1 wherein said sodium borohydride and said first mixture are each encapsulated in a carrier resin prior to heating.

Claim 9

Dependent Claim 22 words

The method of claim 7 wherein said carrier resin is a polymer selected from the group consisting of polyethylene, polystyrene and polypropylene.

Claim 10

Dependent Claim 20 words

The method of claim 8 wherein said sodium borohydride comprises approximately 10 wt % of said polymer encapsulated sodium borohydride.

Claim 11

Dependent Claim 23 words

The method of claim 8 wherein said sodium bicarbonate and citric acid comprise approximately 50 wt % of said polymer encapsulated first mixture.

Claim 12

Dependent Claim 37 words

The method of claim 7 wherein about 0.2 to about 3 parts by weight of said carrier encapsulated sodium borohydride and said carrier encapsulated first mixture are present per 100 parts by weight of said polymer resin.

Claim 13

Dependent Claim 34 words

The method of claim 11 wherein about 2 parts by weight of said carrier encapsulated sodium borohydride and said carrier encapsulated first mixture are present per 100 parts by weight of said polymer resin.

Claim 14

Dependent Claim 22 words

The method of claim 1 wherein said mold comprises a material which undergoes corrosive reactions when subjected to an aqueous acidic environment.

Claim 15

Dependent Claim 12 words

The method of claim 13 wherein said material comprises a ferrous metal.

Claim 16

Dependent Claim 21 words

The method of claim 1 wherein said molded foam article has a density of at least about 25 lbs/ft 3 .

Claim 17

Independent Claim 161 words

A method of making a foam injection molded article, said method comprising the steps of: dispersing into a polymer resin to be foamed (a) an effective amount of a primary chemical blowing agent consisting essentially of sodium borohydride and (b) no more than about 8 parts by weight, per part by weight of said sodium borohydride, of an activation system comprising a first mixture of effective amounts of sodium bicarbonate and citric acid, to form a second mixture of said resin, sodium borohydride and activation system with said sodium borohydride comprising about 0.01-5 weight percent of said second mixture, said sodium borohydride and said activation system being isolated from direct contact with each other until gas production is desired; heating said second mixture whereby said activation system releases water and said sodium borohydride reacts with said water to produce hydrogen gas; and subsequently injecting said second mixture into a mold obtaining expansion of said polymer resin into a molded foam article.

Claim 18

Independent Claim 161 words

A method of making a foam injection molded article, said method comprising the steps of: dispersing into a polymer resin to be foamed (a) an effective amount of a primary chemical blowing agent consisting essentially of sodium borohydride and (b) no more than about 8 parts by weight, per part by weight of said sodium borohydride, of an activation system comprising a first mixture of effective amounts of sodium bicarbonate and citric acid, to form a second mixture of said resin, sodium borohydride and activation system with said sodium borohydride comprising about 0.01-5 weight percent of said second mixture, said sodium borohydride and said activation system being isolated from direct contact with each other until gas production is desired; heating said second mixture whereby said activation system releases water and said sodium borohydride reacts with said water to produce hydrogen gas; and subsequently injecting said second mixture into a mold obtaining expansion of said polymer resin into a molded foam article.

Claim 19

Dependent Claim 21 words

The method of claim 16 wherein said first mixture comprises an approximately equimolar mixture of said citric acid and sodium bicarbonate.

Claim 20

Dependent Claim 25 words

The method of claim 16 wherein about 5 parts by weight of said first mixture are present per part by weight of said sodium borohydride.

Claim 21

Dependent Claim 18 words

The method of claim 16 wherein said sodium borohydride comprises about 0.1-0.3 weight percent of said second mixture.

Claim 22

Dependent Claim 23 words

The method of claim 16 wherein said sodium borohydride and said first mixture are each encapsulated in a carrier resin prior to heating.

Claim 23

Dependent Claim 22 words

The method of claim 20 wherein said carrier resin is a polymer selected from the group consisting of polyethylene, polystyrene, and polypropylene.

Claim 24

Dependent Claim 20 words

The method of claim 21 wherein said sodium borohydride comprises approximately 10 weight percent of said polymer encapsulated sodium borohydride.

Claim 25

Dependent Claim 23 words

The method of claim 21 wherein said sodium bicarbonate and citric acid comprise approximately 50 weight percent of said polymer encapsulated first mixture.

Claim 26

Dependent Claim 39 words

The method of claim 20 wherein from about 0.2 to about 3 parts by weight of said carrier resin encapsulated sodium borohydride and carrier resin encapsulated first mixture are present per 100 parts by weight of said polymer resin.

Claim 27

Dependent Claim 36 words

The method of claim 24 wherein about 2 parts by weight of said carrier resin encapsulated sodium borohydride and said carrier resin encapsulated first mixture are present per 100 parts by weight of said polymer resin.

Claim 28

Dependent Claim 22 words

The method of claim 16 wherein said mold comprises a material which undergoes corrosive reactions when subjected to an aqueous acidic environment.

Claim 29

Dependent Claim 12 words

The method of claim 26 wherein said material comprises a ferrous metal.

Claim 30

Dependent Claim 21 words

The method of claim 16 wherein said molded foam article has a density of at least about 25 lbs/ft 3 .

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-02-21	1992-08-22	1993-02-21	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-02-21	1996-08-22	1997-02-21	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-02-21	2000-08-22	2001-02-21	$7700.00	Window Closed / Lapsed

Method of making a foam injection molded article

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