Uvimers

It was our Initial aim to develop a basic oligomer or family of oligomers that. In suitably formulated systems, were relatively unaffected by the usual Inhibiting action of molecular oxygen. It was fortunate that In the early stages of the synthetic investigations such materials were obtained. Consequently, these newly synthesized oligomer structures became the basis for the Uvimer resins. Variants on the basic structures were later developed to obtain specific end-use properties. 

The principal members of the Uvimer series are uniquely designed unsaturated urethanated oligomers. One method of Incorporating unsaturated functionality Is by reaction of pendant Isocyanate groups with unsaturated compounds containing active hydrogen (See, e.g.. Ref. 1). 

Selected reactive diluents are employed to reduce the viscosity of Uvimer M formulations and to Impart a greater flexibility to the cured product. The choice of a monomer or reactive diluent for a Uvimer ig based on a number of factors, including compatibility with the base resin, odor, volatility, toxicity, and its effect on specific properties such as adhesion. Changing the diluent monomer does not drastically alter the basic properties of the resin so that it is possible to supply a given UvimerTM with a choice of diluents in order to comply with particular user requirements. 

The UvimerTM designation thus represents a generic structural type, while the diluent may be varied for the reasons explained above. For the purposes of this paper, a Uvimer may be shown with a particular reactive diluent or combination of diluents, although this composition is not currently offered commercially. We consider the Uvlmer type to be independent of the particular diluent or diluents employed. 

We will describe typical members of the Uvimer series In terms of their composition and physical properties. UvlmerTM 530, the first member of the series. Is a relatively hard, brittle and fast-curing resin which is suitable for use as an ink vehicle and as a coating on rigid substrates. The table below gives basic formulation and cured film properties of this UvlmerTM ... 

Uvimer 530 exhibits outstanding chemical resistance as evidenced by the data presented in Table II. 

Another member of the Uvimer series is Uvimer 545 whose properties are summarized in Table IV. 

Uvimer 720 (Table VI) is softer and more flexible than 530, 540, and 580 and exhibits improved adhesion to most substrates. 

Because of its superior flexibility and adhesion to many substrates, Uvimer 720 was considered a prime candidate for a floor tile coating. Table VII presents data on two formulations developed for this application. The primary consideration in this Instance was abrasion resistance, with resistance to curl running a close second. Both formulations showed good abrasion resistance, but the formula containing the Increased level of diluent was significantly better as shown by comparison of the results with the 1000 gram weight. 

Data on Uvimer 740 Is presented in Table VII, while Uvimers 765 and 775 are compared in Table VIII, Uvlmer 740 is somewhat stiffer and harder than either 765 or 775, primarily due to the difference in the structures of oligomers D and E. It should also be noted that Uvimers 765 and 775 have better color and do not exhibit yellowing on aging. Since the latter two resins employ the same basic oligomer, it is evident that on the basis of viscosity reduction 2-ethoxyethyl acrylate is a more effective diluent than the 2-ethylhexyl acrylate/hydroxyethyl acrylate combination. Thus, it is possible in Uvimer 775, to employ a lower level of reactive diluent and thereby obtain a harder, stiffer, faster-curing formulation. 

The use of Uvimer diluent RD-30 in a 740 formulation gives a higher viscosity than 2-ethoxyethyl acrylate. However, the odor level is significantly reduced. 

TABLE VII - FLOOR TILE COATINGS BASED ON UVIMER M 720... 

For the past several years, Polychrome Corporation has had under development a family of energy-cur able resins which have been given the trade name of UvimerTM. Several of these materials have reached the commercial stage while others are in an advanced state of development. The present paper describes representative members of the Uvimer family of resins in terms of their basic physical and chemical properties and how these relate to specific end-uses. 

In regard to the relative insensitivity of the Uvimer materials to oxygen inhibition, the mechanism of this is not fully understood at present. However, we believe that it relates to a common structural feature in all of these resins, namely the occurrence of the ethylenic double bonds in a particular position relative to the other functional groups in the oligomer. 

UvimerTM 530 and the other members of the UvimerTM series may be cured with benzoin ether type photoinitiators and with di-ethoxyacetophenone. Table III presents data on the cure speed of Uvimer 530 formulated with butyl benzoin ether. These data were obtained in air without the use of inert blanketing. Films of 3 mil thickness were irradiated on a moving belt using a 5000 watt Addalux uv lamp (Berkey Photo, Inc.) focussed on one linear inch This is a low pressure lamp incorporated in an experimental unit. Faster cure speeds (up to 200 ft. per minute/lamp) were obtained in later studies with a unit employing two medium pressure, 200 watts/linear inch Hanovia lamps. 

A pigmented Uvimer 530 formulation coated on particle board was successfully cured in an electron beam accelerator using one-half the normal nitrogen flow. In the complete absence of nitrogen blanketing, partial curing was obtained. The formulation used was as follows ... 

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