Urea resins; thiourea resins

39.09 - Amino-resins, phenolic resins and polyurethanes, in primary forms. 3909.10 3909.20 3909.30 3909.40 3909.50 - Urea resins; thiourea resins - Melamine resins - Other amino-resins - Phenolic resins - Polyurethanes This heading covers : These are formed by the condensation of amines or amides with aldehydes formaldehyde, -aldehyde, etc. . The most im ortant are urea resins (for example, urea- ormaldehyde), thiourea resins ( or example, t iourea-formaldeh de), melamine resins (for example, melamine-formaldehyde)and aniline resins (for examp e, aniline-formaldehyde). R LP These resins are used for the manufacture of trans arent, translucent or bri tly coloured articles of plastics and are much used for moulding ta le and fancy ware an electrical goods. In solutions and dispersions (emulsions and suspensions), (whether or not modified with oils, fatty acids, alcohols, or other synthetic polymers) they are employed as glues and as textile dressings, etc. (See the General Explanatory Note to this Chapter, exclusion (b), for the classification of glues.) ! r' Poly(methy1ene (often referred to as "crude MDI" or "polymeric MDI" is an opaque, dark brown liquid and is synthesised b the reaction of ani ine and formaldeh de to phenylamine), which is su sequently reacted with phosgene and eat to functions. The product is a chemcally modified polymer of aniline modified amino-resin). The resulting between 4 and 5, and is an important polymer has an prepolyrner used in the manufacture of polyurethanes. K z Polyamine resins, such as poly(eth leneamines), are not amino-resins and fall in heading 39.11 when complying with the requirements of h t e 3 to this Chapter. (2) Phenolic resins This group comprises a wide or its homologues (cresol, formaldehyde, the conditions under introduction of other substances. materials derived from the condensation of phenol substituted phenols, with aldehydes such as The nature of the products varies according to and whether it is modified by the Thus the group includes (a) Resins (novolaks), which are permanently fusible and soluble in alcohol or other organic solvents, and which are produced under acid conditions. These are used in the preparation of varnishes and moulding powders, etc. @) Thermosetting phenolic resins, which are obtained under alkaline conditions. In the rocessing, a continuous ran e of products is obtained. Firstly, the resols in the f o m of Equids, pastes or solids whic are used as varnish bases, irnpregnants, etc. Secondly, the resitols which are in the form of moulding powders, and finall after complete reaction, resites which are most often in finished forms such as plates, s eets, rods, tubes or other articles generally classified in headings 39.16 to 39.26. f Certain resins of this kind are ion-exchangers and fall in heading 39.14. (c) Oil-soluble phenolic resins (soluble in drylng oils) prepared from butylphenol, amylphenol, parahydroxydiphenyl or other substituted phenols. They are used mainly ~nthe preparation of varnishes. (d) Products based on the resins referred to at (a), (b). and (c) above modified by the mcorporation of rosin or other natural resins, synthetic resins (es ecially alkyd resins), vegetable oils, alcohols, organic acids or other chemicals which a fect their solubility in drying oils. These products are used in the preparation of varnishes and paints, as surface-coatings or impregnants. P (3) Polyurethanes This class includes all olyrners produced by the reaction of olyfUnctional isoc anates with polyh droxy compoun s, such as, castor oil, butane-1,4-dio, polyether polyo s, pol ester polyo s. Polyurethanes exist in various forms, of which the most mportant are the zams, elastomers, and coatings. The are also used as adhesives, moulding compounds and fibres. These products are often trade as one part of a multi-component system or set." f P 'f 2' This group also includes mixtures of polyurethane and unreacted polyfunctional diisocyanate (e.g., toluene diisocyanate). For the classification of pol ers (including cop01 ers), chemically modified polymers and polymer blends, see the General Exp anatory Note to this C apter. Y K"