PRODUCT AND METHOD OF MANUFACTURE

This invention relates to the production of plastics materials.

Certain polymers, such as polyurethanes are made from a polyol and a polyisocyanate. Polyols commonly used include polyethers, such as polyethylene glycol and polypropylene glycol, and polyesters. Usually, these components are of mineral origin. Proposals have been made in the last couple of decades to substitute bio-derived materials, primarily of vegetable origin. WO90/05148 discloses the use of lactose in making polyurethane foams.

The present invention provides a new bio-derived polyol component for the manufacture of plastics materials, particularly, but not exclusively, rigid foam materials such as rigid foam polyurethane.

The invention comprises, in one aspect, a polyol, as a component of a polyol- polyisocyanate reaction polymer producing process, comprising a chemically unmodified milk product.

Suitable milk products comprise waste milk, such as antibiotic milk waste - this is milk that cannot be introduced into the food chain because of a high antibiotic content - and milk residue products, which include skim milk powder, whey permeate, whey protein concentrate, and delactose whey permeate. A residue is what is left after one or more useful products have been removed from whole milk - there is often no useful purpose to which such resides can be put currently.

The milk products above-mentioned can be used individually or mixed together.

Antibiotic milk waste used for present purposes need only be skimmed to remove its cream. Delactose whey permeate is what is left after lactose has been extracted from whey permeates. It may still have a major lactose content, and may comprise some 70% lactose, 9-10% damaged protein, and the balance minerals, including calcium phosphate.

The component may be comprised in powder form, and may comprise less than 2%, preferably less than 1%, water by weight. Aside from controlling water content, the materials may be used essentially unmodified.

Prior art proposals to use lactose and sucrose as components in the manufacture of polymer materials have required them to be chemically modified.

The polyol component of the invention may include at least one additive, which may be a free flow additive, which may comprise tricalcium phosphate. The phosphate content imparts fire retardant properties to the finished product. Further mineral may be added, which may also be derived from milk, e.g. from demineralisation of whey powder in the production of baby formula, or from any other source, to impart desired properties, e.g. fire retardancy, to the finished product.

The milk product may comprise a substantial proportion of a total polyol component of the polymer producing process, replacing, say, between 5% and 60% of the conventionally used polyol in the mix, but it may also be possible, at least for certain end uses of the polymer, to replace up to 100% of the conventional polyol

The powder form of the milk product may be obtained in any convenient way, as by spray drying, vacuum drying or freeze-drying - generally speaking, any method of drying that does not degrade the material can be used.. The powder will generally be hygroscopic, and, if produced with controlled moisture content suitable for use directly in the polymer producing process, will, according to another aspect of the invention, be stored and transported sealed against ingress of moisture.

The invention also comprises a method for making polymer material comprising reacting a polyol and a polyisocyanate, in which the polyol comprises a chemically unmodified milk product.

The waste milk product may be added as a powder, dried to comprise less than 2%, preferably less than 1% water.

The waste milk product may comprise, or have added, phosphate, particularly calcium phosphate, more particularly tricalcium phosphate, the latter present as a free running agent, and may comprise added mineral content e.g. from demineralisation of whey powder.

The waste milk product may comprise a substantial proportion of total polyol component for the reaction, and may comprise between 5% and 100% by weight of the total, preferably between 20% and 100%.

The method may be used to make a foam material, particularly a rigid foam material. The polyol and polyisocyanate may be reacted together with a foaming agent in the presence of a catalyst. The foaming agent may comprise water.

The invention also comprises a polymer material made from reacting polyol and polyisocyanate components of which the polyol component comprises a waste milk product.

The polymer material may comprise mineral content from the waste milk product, and may comprise calcium phosphate, particularly tricalcium phosphate. The polymer material may have fire retardant properties stemming from the phosphate content. The polymer material may comprise added mineral content derived from demineralising milk powder.

A polyol component of a polymer producing process, a method for making the same, a method for storing and transporting the same, manufacture of polymer material using the same and polymer material manufactured thereby, all according to the invention, will now be more particularly described.

A polyol component is prepared from antibiotic milk waste by skimming the milk to remove cream and then spray drying to a final moisture content of 1% by weight, as may be determined, for example, by an infra-red or microwave moisture sensor. To the spray dried powder is added tricalcium phosphate as a free running agent.

The powder is bagged in lined bags to prevent ingress of moisture during storage and transportation.

The polymer is made by reacting, in the usual way, the thus-derived polyol component with a polyisocyanate. The polyol component is used in substitution for 50% of the usual polyol for the process, but could be used as 5% to 60% or even up to 100% of the total polyol component. For the manufacture of rigid foam, the reaction mix comprises a foaming agent such as water and the reaction is catalysed.

The resulting rigid foam product has a phosphate content imparting fire retardant properties as a result of the intrinsic phosphate content of the waste milk product, as well as the added tricalcium phosphate.

Additional mineral content may be added comprising waste mineral from demineralising milk powder for baby formula.

Of course, should naturally occurring mineral content not be desired, the milk product can be demineralised.

Polyol component made from delactose whey permeate may be used instead of the antibiotic milk waste in exactly the same way.

The rigid foam may be used in building construction.