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US 6,787,237 B2Granted
Room temperature stable epoxy prepregs
AssigneeHexcel Corporation
InventorsMartin Simmons, John Cawse, John Ellis
Life of this patent
Estimating the term…
Abstract
Uncured composite materials (prepreg) are provided that are stable at room temperature over relatively long periods of time. The prepreg includes a solid epoxy resin matrix composed of a crystalline epoxy resin and a solid curing agent. The curing agent is preferably crystalline. The prepreg may include one or more property enhancement layers that increase the tackiness of the prepreg, increase the flexibility of the prepreg and/or reduce the amount of solid resin matrix that flakes from the prepreg during handling.
Claims29
An uncured composite material comprising:
- an uncured composite body having at least one side, said composite body comprising fibers and a substantially crystallized solid matrix, said solid matrix comprising a solids mixture of a crystallized epoxy resin and a solid curing agent, wherein said side of said uncured composite body has a certain level of tackiness and said uncured composite body has a certain degree of flexibility;
- and
- one or more property enhancement agents located on said side of said uncured composite body, said property enhancement agent or agents present in a sufficient amount to provide an increase in the tackiness of said uncured composite body and an increase in the flexibility of said uncured composite body.
A method for storing an uncured composite material, said method comprising the steps of:
- providing an uncured composite body having at least one side, said composite body comprising fibers and a substantially crystallized solid matrix, said solid matrix comprising a solids mixture of a crystallized epoxy resin and a crystallized curing agent wherein said epoxy resin has a crystal melting point and said curing agent has a crystal melting point wherein said side of said uncured composite body has a certain level of tackiness and said uncured composite body has a certain degree of flexibility, said uncured composite material further comprising a property enhancement layer located on said side of said uncured composite body, said property enhancement layer comprising a sufficient amount of a property enhancement agent to provide an increase in the tackiness of said uncured composite body and an increase in the flexibility of said uncured composite body;
- and
- storing said uncured composite body at a temperature that is below the crystal melting points of both said epoxy resin and said curing agent.
A method for storing an uncured composite material comprising the steps of:
- providing an uncured composite body having at least one side, said composite body comprising fibers and a substantially crystallized solid matrix, said solid matrix comprising a solids mixture of a crystallized epoxy resin and a solid curing agent wherein said epoxy resin has a crystal melting point and said solid curing agent has a melting point, wherein said side of said uncured composite body has a certain level of tackiness and said uncured composite body has a certain degree of flexibility such that a certain amount of said solid matrix flakes from said uncured composite body when said uncured composite body undergoes flexing, and wherein said composite material further includes a property enhancement layer located on said side of said uncured composite body, said property enhancement layer comprising a sufficient amount of a property enhancement agent to provide an increase in the tackiness of said uncured composite body, an increase in the flexibility of said uncured composite body and/or a reduction in the amount of said solid matrix flaking from said uncured composite body;
- and
- storing said uncured composite body at a temperature that is below the crystal melting point of said epoxy resin and below the melting point of said curing agent.
A method for making an uncured composite material comprising the steps of:
- forming an uncured composite body having at least one side, said composite body comprising fibers and a substantially crystallized solid matrix, said solid matrix comprising a solids mixture of a crystallized epoxy resin and a solid curing agent, wherein said side of said uncured composite body has a certain level of tackiness and said uncured composite body has a certain degree of flexibility wherein a certain amount of said solid matrix flakes from said uncured composite body when said uncured composite body undergoes flexing;
- and
- forming a property enhancement layer located on said side of said uncured composite body, said property enhancement layer comprising a sufficient amount of a property enhancement agent to provide an increase in the tackiness of said uncured composite body, an increase in the flexibility of said uncured composite body and/or a reduction in the amount of said solid matrix flaking from said uncured composite body.
Dependencies are inferred from the claim text.