Method and composition for controlled thickening of thermosetting resins using microencapsulated thickeners

• US 4,876,296 A
• Filed: 04/27/1987
• Issued: 10/24/1989
• Est. Priority Date: 04/27/1987
• Status: Expired due to Fees

• Current Assignee: OLIN Corporation
• Original Assignee: OLIN Corporation
• Inventors: Miller, J. Stanley, Bowles, Thomas J.
• Primary Examiner(s): Kight, John
• Assistant Examiner(s): Nutter, Nathan M.
• Application Number:
  US07/043,055
• Time in Patent Office: 911 Days
• Field of Search: 523/201, 523/202, 523/448, 523/200, 427/213.3, 427/213.36, 524/401, 524/433, 524/40, 428/402.24
• US Class Current: 523/200
• CPC Class Codes: B01J 13/025 Applications of microcapsules not provided for in other subclasses
• CPC Class Codes: C08K 9/10 Encapsulated ingredients
• CPC Class Codes: Y10T 428/2989 Microcapsule with solid core [includes liposome]

Abstract

A method and composition employing microencapsulated thickeners for providing controlled thickening of thermosetting resins, including sheet molding compositions.

Claims

1. A composition comprising at least one unsaturated polyester, at least one thermoplastic low-profile additive, at least one binder selected from the group consisting of reinforcing agents, fillers, and combinations thereof, at least one microencapsulated thickener, and a catalyst selected from the group consisting of peroxyesters, peroxyketones, peroxyketals, and mixtures thereof, and wherein said microencapsulated thickener comprises microcapsules having a capsule shell of at least one thermoplastic polymer and a capsule core containing a thickener selected from the group consisting of magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, and combinations thereof, and wherein said capsule shells comprise a thermoplastic polymer selected from the group consisting of polyethylene, polystyrene, cellulose acetate butyrate, and combinations thereof, and wherein said microcapsules have a particle size of between about 5 and about 30 microns, said low-profile additive being a polyurethane oligomer having a molecular weight of between about 10,000 and about 30,000.

2. A method for fabricating a composition characterized by a controlled thickening capability which comprises adding rupturable microcapsules of at least one microencapsulated thickener to a composition comprising at least one unsaturated polymer, at least one thermoplastic low-profile additive, at least one binder selected from the group consisting of reinforcing agents, fillers, and combinations thereof, and a catalyst selected from the group consisting of peroxyesters, peroxyketones, peroxyketals, and mixtures thereof, and wherein said microencapsulated thickener comprises microcapsules having a capsule shell of at least one thermoplastic polymer and a capsule core containing a thickener selected from the group consisting of magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, and combinations thereof, and wherein said capsule shells comprise a thermoplastic polymer selected from the group consisting of polyethylene, polystyrene, cellulose acetate butyrate, and combinations thereof, and wherein said microcapsules have a particle size of between about 5 and about 30 microns, said low-profile additive being a polyurethane oligomer having a molecular weight of between about 10,000 and about 30,000.

3. A method of forming a microcapsules having a shell of thermoplastic polymer and a core of at least one microcapsuled thickener which comprises coating thickener particles of said thickener selected from the group consisting of magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, and mixtures thereof with a thermoplastic polymer to form said microcapsules containing a core of said thickener particles, wherein said method is effected by the in situ polymerization of monomers in a dispersion of said particles of said thickener in an aqueous or organic solvent, or mixture thereof, thereby forming said microcapsules having a thermoplastic polymer shell and a core of thickener particles, and wherein said microencapsulated thickener comprises microcapsules having a capsule shell of at least one thermoplastic polymer and a capsule core containing a thickener selected from the group consisting of magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, and combinations thereof, and wherein said capsule shells comprise a thermoplastic polymer selected from the group consisting of polyethylene, polystyrene, cellulose acetate butyrate, and combinations thereof, and wherein said microcapsules have a particle size of between about 5 and about 30 microns.