Polyurethane foam molding with zones of different indentation hardness and a process for its production

• US 4,379,856 A
• Filed: 01/15/1982
• Issued: 04/12/1983
• Est. Priority Date: 01/23/1981
• Status: Expired due to Term

• Current Assignee: Hennecke GmbH (Hennecke Group GmbH)
• Original Assignee: Bayer AG
• Inventors: Samaritter, Reinhard, Volland, Robert, Schoberth, Winfried
• Primary Examiner(s): WELSH JR, MAURICE
• Application Number:
  US06/339,595
• Time in Patent Office: 452 Days
• Field of Search: 521/51, 521/159, 521/160, 521/917, 521/79, 264/45.1, 264/45.5, 264/45.8, 264/46.2, 264/46.3, 296/63
• US Class Current: 521/51
• CPC Class Codes: B29C 44/0461 by having different chemical compositions in different places, e.g. having different concentrations of foaming agent, feeding one composition after the other
• CPC Class Codes: B60N 2/70 Upholstery springs ; Upholstery
• CPC Class Codes: C08G 18/14 Manufacture of cellular products
• CPC Class Codes: C08G 18/7664 containing alkylene polyphenyl groups
• CPC Class Codes: Y10S 521/917 Specialized mixing apparatus utilized in cell forming process
• CPC Class Codes: Y10T 428/249981 Plural void-containing components

Abstract

A deformable and durable polyurethane foam molding is made from the reaction product of a polyether polyol component and a polyisocyanate component. The polyether polyol component is a polyether having at least two hydroxyl groups, a molecular weight of from 400 to 10,000 and at least 10 wt. % hydroxyl groups which are primary hydroxyl groups. The polyisocyanate component is a mixture of from 60-90 wt. % 4,4'"'"'-diphenyl methane diisocyanate and from 3-30 wt. % 2,4'"'"'-diphenyl methane diisocyanate. Such reaction mixture is prepared in each of at least two mixing heads. The index of reaction mixture is different from that in the other mixing head. The mixture is then introduced into associated zones of a mold cavity where the mixture is allowed to foam. The molding is subsequently removed from the mold cavity. These polyurethane foam moldings are particularly useful in making seat cushions.

Claims

1. A polyurethane molding having zones of different hardness in which the polyurethane foam molding is a reaction product of:

a a polyether polyol component containing at least two hydroxyl groups and having a molecular weight of from 400 to 10,000 in which at least 10 wt. % of the hydroxyl groups are primary hydroxyl groups; and

b a polyisocyanate component which is a mixture of diphenyl methane diisocyanates and oligomeric polyphenyl polymethylene polyisocyanates which mixture contains from 60-90 wt. % 4,4'"'"'-diphenyl methane diisocyanate and from 3 to 30 wt. % 2,4'"'"'-diphenyl methane diisocyanate,

said reaction product having (i) zones of different hardness as indicated by a difference between the indices of the reaction mixture for those zones and (ii) transition zones between said zones (i) which transition zones are free from any hardening.

2. The molding of claim 1 wherein the polyisocyanate component is a mixture of 65-80 wt. % 4,4'"'"'-diphenyl methane diisocyanate and 10-30 wt. % 2,4'"'"'-diphenyl methane diisocyanate.

3. The molding of claim 1 which is a cushion for a vehicle seat having a relatively soft stress zone and relatively firm lateral support zones wherein the lateral support zones are made up of ridges extending into the stress zones.

4. The molding of claim 3 wherein the ridges are in the form of tapering lobes.

5. The molding of claim 3 wherein the ridges are in the form of collars.

6. The molding of claim 1 which is a cushion for a vehicle seat having a relatively soft stress zone and relatively firm lateral support zones in which the soft stress zone is made up of ridges extending into the lateral support zones.

7. The molding of claim 6 wherein the ridges are in the form of tapering lobes.

8. The molding of claim 6 wherein the ridges are in the form of collars.

9. A process for the production of a polyurethane foam molding having zones of different hardness comprising:

a introducing a foamable reaction mixture into associated zones of a mold cavity by means of at least two mixing heads in each of which the reaction mixture has a different index from that of the reaction mixture in the other mixing head;

b allowing the reaction mixture to foam; and

c removing the mold after foaming is substantially complete wherein the foamable reaction mixture is made up of

(i) a polyether polyol component having at least two hydroxyl groups and a molecular weight of from 400 to 10,000 in which at least 10 wt. % of the hydroxyl groups are primary hydroxyl groups; and

(ii) a polyisocyanate component which is a mixture comprising from 60-90 wt. % 4,4'"'"'-diphenyl methane diisocyanate and from 3-30% wt. % 2,4'"'"'-diphenyl methane diisocyanate.

10. The process of claim 9 wherein the reaction mixture is introduced into the zones of the mold in a manner such that streams of the mixture are introduced from the mixing heads flow against and into one another.

11. Polyurethane foam molding, produced by use of the process according to claim 9.