System, method and composition for forming composite sprayed polyurethane skins having an expanded polyurethane layer

1 . A method for making a composite polyurethane skin, said method comprises:

providing a source of liquid polyol;

providing a source of liquid isocyanate;

providing a source of liquid blowing agent;

providing a spray mold tool having a mold surface;

providing a spraying device for spraying liquid material at the spray mold tool;

directing polyol and isocyanate to the spraying device to form a polyurethane composition;

spraying the polyurethane composition towards the spray mold tool to form a polyurethane skin layer on the spray mold tool;

directing polyol, isocyanate and blowing agent to the spraying device to form an expandable polyurethane composition; and

spraying the expandable polyurethane composition onto the skin layer to form a resilient expanded polyurethane layer on the skin.

2 . The method of claim 1 wherein the resilient layer has a density of 0.1 to 0.75 g/cm 3 .

3 . The method of claim 1 wherein the expandable polyurethane composition comprises polyol present in an amount of 50 to 90 weight percent, isocyanate present in an amount of 15 to 45 weight percent and blowing agent in an amount of 0.1 to 6 weight percent.

4 . The method of claim 3 wherein the blowing agent comprises an agent selected from the group consisting of a delayed-action catalyst and water.

5 . The method of claim 4 wherein the blowing agent comprises both catalyst and water.

6 . The method of claim 3 wherein the polyol in the expandable composition is provided to the spraying device in a first stream, the isocyanate in the expandable composition is provided to the spraying device in a second stream and the blowing agent in the expandable composition is provided to the spraying device in a third stream.

7 . The method of claim 3 wherein a first portion of the polyol in the expandable polyurethane composition is provided to the spraying device in a first stream, a second portion of the polyol in the expandable polyurethane composition is provided to the spraying device in a second stream, separate from the first stream, and the blowing agent is provided to the spraying device in the second stream.

8 . The method of claim 7 wherein the streams are delivered to the spraying device in the following manner:

STREAM

WEIGHT PER SECOND

Polyol

8 to 14

grams per second

Isocyanate

3.5 to 6.0

grams per second

Blowing Agent

0.1 to 2

grams per second

9 . The method of claim 2 wherein the polyurethane skin has a thickness of 0.4 to 2 mm.

10 . The method of claim 9 wherein the resilient layer has a thickness of 0.1 to 15 mm and a shore A hardness of 30 to 50.

11 . The method of claim 5 wherein the expandable polyurethane composition comprises:

COMPONENT

WEIGHT %

Polyol

50 to 90%

Isocyanate

15 to 45%

Delayed-Action Amine Catalyst

0.1 to 5%  

Water

0.05 to 5.0%

12 . A sprayable expandable polyurethane composition for forming a sprayed skin, said composition comprising:

polyol;

isocyanate; and

blowing agent, wherein the components are present in an amount such that a resulting layer of polyurethane, when cured, will have a density in the range of 0.1 to 0.75 g/cm 3 .

13 . The composition of claim 12 wherein the expandable polyurethane composition comprises polyol in an amount of 50 to 90 weight percent, isocyanate present in an amount of 15 to 45 weight percent and blowing agent present in an amount of 0.1 to 6 weight percent.

14 . The composition of claim 13 wherein the blowing agent comprises at least one component selected from the group consisting of catalyst and water.

15 . The composition of claim 14 wherein the blowing agent comprises a delayed-action amine catalyst and water.

16 . The composition of claim 15 wherein the composition comprises:

COMPONENT

WEIGHT %

Polyol

50 to 90%

Isocyanate

15 to 45%

Catalyst

0.1 to 5%  

Water

0.05 to 5.0%

17 . A system for making a composite polyurethane skin, system comprising:

a source of liquid polyol;

a source of liquid isocyanate;

a source of liquid blowing agent;

a spray mold tool having a mold surface; and

a spraying device for spraying liquid material at the spray mold tool;

the spraying device being able to receive polyol from the polyol source and isocyanate from the isocyanate source to form a polyurethane composition for spraying towards the spray mold tool to form a polyurethane skin layer on the spray mold tool;

the spraying device being able to receive isocyanate from the isocyanate source, blowing agent from the blowing agent source, and polyol to form an expandable polyurethane composition for spraying onto the skin layer to form a resilient expanded polyurethane layer on the skin.

18 . The system of claim 17 wherein the polyol in the expandable composition is provided to the spraying device in a first stream, the isocyanate in the expandable composition is provided to the spraying device in a second stream and the blowing agent in the expandable composition is provided to the spraying device in a third stream.

19 . The system of claim 17 wherein a first portion of the polyol in the expandable polyurethane composition is provided to the spraying device in a first stream, a second portion of the polyol in the expandable polyurethane composition is provided to the spraying device in a second stream, separate from the first stream, and the blowing agent is provided to the spraying device in the second stream.

20 . The system of claim 19 wherein the streams are delivered to the spraying device in the following manner:

STREAM

WEIGHT PER SECOND

Polyol

8 to 14

grams per second

Isocyanate

3.5 to 6.0

grams per second

Blowing Agent

0.1 to 2

grams per second