US5077319A — Cyanate resin-based foams

Claim 1

Independent Claim 70 words

A mixture capable of being simultaneously cured and formed into a structural foam, comprising: (a) 5-63.38% by weight cyanate ester, (b) 34.13-90% by weight thermoplastic polymer selected from the group consisting of polysulfones, polyethersulfones, polyimides, polyacrylates, polyetherethylketones, polyetherimides, polyvinylformals and mixtures thereof, (c) 0.1-15% by weight blowing agent selecting from the group consisting of 5-phenyltetrazole, p-toluenesulfonyl semicarbazide, azodicarbonamide, urea, dimethylurea, formamide and mixtures thereof, and (d) 0.1-5.0% by weight surfactant.

Claim 2

Dependent Claim 70 words

A mixture capable of being simultaneously cured and formed into a structural foam, comprising: (a) 5-63.38% by weight cyanate ester, (b) 34.13-90% by weight thermoplastic polymer selected from the group consisting of polysulfones, polyethersulfones, polyimides, polyacrylates, polyetherethylketones, polyetherimides, polyvinylformals and mixtures thereof, (c) 0.1-15% by weight blowing agent selecting from the group consisting of 5-phenyltetrazole, p-toluenesulfonyl semicarbazide, azodicarbonamide, urea, dimethylurea, formamide and mixtures thereof, and (d) 0.1-5.0% by weight surfactant.

Claim 3

Dependent Claim 10 words

The mixture of claim 1, wherein said catalyst is azodicarbonamide.

Claim 4

Dependent Claim 24 words

The mixture of claim 1, wherein said thermoplastic is comprised, at least partially, of molecules terminated in an end group having an active hydrogen.

Claim 5

Dependent Claim 25 words

The mixture of claim 3, wherein said end group is selected from the group consisting of NH 2 , COOH, phenol, OH and mixtures thereof.

Claim 6

Dependent Claim 13 words

The mixture of claim 4, wherein said end group is comprised of OH.

Claim 7

Dependent Claim 18 words

The mixture of claim 1, wherein said thermoplastic is micropulverized, having an average particle diameter of 5-100 microns.

Claim 8

Dependent Claim 14 words

The mixture of claim 6, wherein said thermoplastic is substantially dissolved in said mixture.

Claim 9

Dependent Claim 46 words

A B-staged film precursor of a structural foam, prepared by heating the mixture of claim 1 at a temperature of 15°-150° C. for a period of 5-60 minutes, preparing a film of said heated mixture, and heating it to a temperature sufficient to B-stage said film.

Claim 10

Dependent Claim 23 words

The precursor of claim 8, wherein said film is B-staged by heating at a temperature of 80°-150° C. for period of 5-50 minutes.

Claim 11

Dependent Claim 30 words

The precursor of claim 8, wherein said surface is sufficiently tacky that a plurality of said precursors may be layered together, and subsequently foamed to form a monolithic structural foam.

Claim 12

Dependent Claim 17 words

The film precursor of claim 8, wherein substantially all of said thermoplastic is dissolved in said film.

Claim 13

Dependent Claim 69 words

A structural foam comprised of polycyanurate in an amount of 5-63.38% by weight, with thermoplastic added thereto in an amount of 34.13-90% by weight, said thermoplastic being selected from the group consisting of polysulfones, polyethersulfones, polyimides, polyacrylates, polyetherethylketones, polyetherimides, polyvinylformals and mixtures thereof, said foam having a uniform fine cell structure, a compressive strength of at least about 50 psi, and a density of at least about 3.0 pcf.

Claim 14

Dependent Claim 69 words

A structural foam comprised of polycyanurate in an amount of 5-63.38% by weight, with thermoplastic added thereto in an amount of 34.13-90% by weight, said thermoplastic being selected from the group consisting of polysulfones, polyethersulfones, polyimides, polyacrylates, polyetherethylketones, polyetherimides, polyvinylformals and mixtures thereof, said foam having a uniform fine cell structure, a compressive strength of at least about 50 psi, and a density of at least about 3.0 pcf.

Claim 15

Dependent Claim 15 words

The structural foam of claim 12, wherein said thermoplastic is present in 30-50%, by weight.

Claim 16

Dependent Claim 17 words

The structural foam of claim 12, wherein said thermoplastic comprises a terminal group having a reactive hydrogen.

Claim 17

Dependent Claim 19 words

The foam of claim 12, wherein said thermoplastic is a polyether sulfone thermoplastic with terminal groups an OH moiety.

Claim 18

Dependent Claim 88 words

The structural foam of claim 12, wherein said polycyanurate is comprised of cyanate esters of the formula ##STR3## wherein each R may be the same or different and is selected from the group consisting of H, C 1-6 alkyl, C 1-6 alkoxy, phenyl and mono, di and tri-substituted phenyl wherein the substituents may be drawn from the non-phenyl identities for R, halogen, aryl, aryloxy, nitro or thio groups bearing an alkyl, aryl or alkyloxy group, and a carboxylic acid group, and wherein x is any bisphenol linking group.

Claim 19

Independent Claim 128 words

A method of preparing a structural foam, comprising mixing a cyanate ester with a thermoplastic resin, said cyanate ester being present in an amount of 5-95%, by weight, and said thermoplastic being present in an amount of 1-90%, by weight, together with a surfactant in an amount of 0.01-5.0%, by weight, and a catalyst and blowing agent, totaling up to 15%, by weight, said mixing being conducted at a temperature of 15°-150° C. for a period of 5-60 minutes to form a foam precursor, thereafter casting the resultant mixture as a thin film and B-staging said thin film at 120°-150° C. for a period of 5-50 minutes, heating said B-staged foam precursor to a temperature of 150°-230° C. for a period of 1-2 hours, and recovering said foam.

Claim 20

Independent Claim 128 words

A method of preparing a structural foam, comprising mixing a cyanate ester with a thermoplastic resin, said cyanate ester being present in an amount of 5-95%, by weight, and said thermoplastic being present in an amount of 1-90%, by weight, together with a surfactant in an amount of 0.01-5.0%, by weight, and a catalyst and blowing agent, totaling up to 15%, by weight, said mixing being conducted at a temperature of 15°-150° C. for a period of 5-60 minutes to form a foam precursor, thereafter casting the resultant mixture as a thin film and B-staging said thin film at 120°-150° C. for a period of 5-50 minutes, heating said B-staged foam precursor to a temperature of 150°-230° C. for a period of 1-2 hours, and recovering said foam.

Claim 21

Dependent Claim 22 words

The process of claim 17, further comprising post-curing said foam at a temperature of 200°-220° C. for a period of 2-8 hours.

Claim 22

Dependent Claim 24 words

The process of claim 17, wherein said thermoplastic is added in the form of micropulverized particles having an average particle dimension of 5-100 microns.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-12-30	1995-07-01	1995-12-31	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-12-30	1999-07-01	1999-12-31	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-12-30	2003-07-01	2003-12-31	$7700.00	Window Closed / Lapsed

Cyanate resin-based foams

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