Method of treating uncured thermosetting resin matrices
AssigneeHexcel Composites Limited
InventorsEsteban Villalon, Jimmy Grondin
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Abstract
Treating an uncured resin to impart energy to the resin enables a stable Tg to be achieved whereby the resin may be stored and has a low tack enabling subsequent processing and handling. The invention provides a method of achieving a stable Tg without the resin starting to cure and a method of determining the treatment regime by which a resin with a stable Tg may be obtained. The resin may be fresh or reused uncured resin and may contain fibrous reinforcement.
Claims22
A method of producing a stabilised uncured resin matrix composition comprising providing an uncured resin matrix composition having an initial glass transition temperature (Tg) and subjecting the resin matrix composition to:
- i. a first regime comprising imparting energy to the uncured resin matrix composition to raise the Tg by at least 5% to provide a raised Tg whereby the residual cure of the resin matrix is reduced by a maximum of 20%, preferably a maximum of 10% and more preferably a maximum of 5%;
- and
- ii. a second regime comprising storing the uncured resin matrix composition to provide a stabilised uncured resin matrix composition wherein the Tg of the stabilised uncured resin matrix composition is such that it does not increase by more than 10% from the raised Tg when stored for 14 days.
A method according to claim 14 wherein the fibrous reinforcement material pre-impregnated with an uncured resin matrix composition comprises an unused or uncured composite.
A method of determining a treatment regime for stabilising the glass transition temperature (Tg) of a curable resin matrix composition comprising:
- i. providing a resin matrix composition wherein the resin matrix composition may be uncured having an initial Tg and selecting a first regime comprising an elevated temperature to impart energy to the uncured resin matrix composition whereby the residual cure of the resin matrix is reduced by a maximum of 20%, preferably a maximum of 10% and more preferably a maximum of 5%;
- ii. imparting energy to the resin matrix composition in the first regime so as to increase the Tg of the resin matrix composition;
- iii. selecting a second regime comprising storing the resin matrix composition wherein the second regime is different to the first regime;
- iv. subjecting the resin matrix composition to the second regime whereby the residual cure of the resin matrix is reduced by a maximum of 10%;
- vi) measuring the Tg of the resin matrix composition periodically until over a selected period of time ranging from 12 hours to 144 hours or periods thereof either:
- a. the periodically measured Tg does not increase by more than 1%, or 2%, or 4%, or 5% or 10% from the raised Tg thereby determining the conditions of the first regime and the second regime;
- or
- b. where the periodically measured Tg increases by more than 1%, or 2%, or 4%/o, or 5% or 10% from the raised Tg, modifying the first regime and/or second regime and repeating steps ii), iv) and v) until the periodically measured Tg does not increase by more than 1%, or 2%, or 4%, or 5% or 10% from the raised Tg.
A treated uncured or unused resin matrix composition having a stable glass transition temperature (Tg) at ambient temperature wherein the uncured resin matrix composition has a raised Tg after being treated and the Tg of the treated uncured resin matrix composition remains within 10% of the initial raised Tg when stored for at least 1 day.
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Dependencies are inferred from the claim text.