Modified resins made from the reaction of epoxidized esters and

Details Modified resins made from the reaction of epoxidized esters and Modified resins made from the reaction of epoxidized esters and

1996-09-18

1998-06-23

Gulakowski, Randy

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

528110, 5281115, 5282955, 528297, C08F28300

Patent

active

057706620

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to tackifier resins for adhesives based on epoxy-modified resin acids, to a process for their production and to their use in adhesives.
2. Prior Art
So-called tackifier resins are added to numerous polymer-based adhesives to modify and improve their adhesive properties. They are intended to increase the tackiness or the adhesion of the adhesives. The properties of the adhesive are ultimately determined by the formulation of the polymer/tackifier resin mixture.
Commercially available resins can be divided into two main groups, namely: resins based on natural resin acids and hydrocarbon resins.
The resin acids may be used in pure form or after modification, for example by disproportionation, addition of maleic anhydride or esterification with polyhydric alcohols, such as glycerol, trimethylol propane or pentaerythritol.
The pure resin acids have a number of disadvantages. For example, their resistance to autoxidation is inadequate. In addition, they tend to crystallize out after prolonged storage in dissolved form. Resin acids produced from tall oil have an unpleasant odor on account of the sulfur content of the crude products.
The phenomenon of resin crystallization is discussed in detail in the book by W. Sandermann entitled "Naturharze, Terpentinol, Tallol, Chemie und Technologie", pages 175-185, Springer, Berlin, 1960. The same book also describes processes which lead to a reduction in the tendency towards crystallization, including for example a thermal process in which the resins are heated to temperatures above 200.degree. to 300.degree. C. The isomerization which occurs leads to a reduction in the tendency towards crystallization. Other processes mentioned include disproportionation of the resins with elemental iodine or sulfur and the addition of formaldehyde.
EP-A2 0 520 541 describes a process in which resin acids are heated in the presence of phosphoric acid and are subsequently disproportionated by addition of iodine. The softening point of the resin acids and their tendency to crystallize are reduced by this process.
Routine deodorizing processes, such as steaming, passing nitrogen through the melt and distillation, may be used to reduce the odor of tall oil resins.
Unfortunately, known processes are attended by various disadvantages. Heat treatment on its own is unable adequately to reduce the tendency of the resins to crystallize. Although disproportionation with iodine, optionally in combination with phosphoric acid, is far more effective, halogenated hydrocarbons which are undesirable on account of their toxicological potential are formed by addition of iodine onto double bonds still present.
The deodorization of tall oil resin by conventional methods is unsatisfactory, presumably because some of the sulfur compounds responsible are substantially non-volatile.
The reaction of resin acids with glycidyl esters is also known, for example from R. N. Wheeler, Paint Technology 19, 159 (1955) or L. Korfhage, Deutsche Farbenzeitschrift, 9, 463 (1955). These publications describe the reaction of diglycidyl ethers of bisphenol A or its autocondensation products with resin acids or fatty acids. The compounds are used as raw materials for paints.
Aqueous dispersion adhesives for various applications, for example as pressure-sensitive adhesives, contact adhesives or flooring adhesives, have also been known for some time. They consist essentially of a polymer dispersion to which tackifier resins may be added to modify or adjust the adhesive properties. Since known tackifier resins are not added to the dispersion in solid form, they are added in the form of a solution, optionally at relatively high temperatures. A particularly suitable solvent for this purpose is toluene because, even in very small quantities, it is capable of preventing the resins from crystallizing out. However, the use of aromatic solvents is being increasingly restricted on toxicological and industrial hygiene grounds. Through the reduction and substitution

REFERENCES:
patent: 3632855 (1972-01-01), Halbrook et al.
patent: 3873482 (1975-03-01), Severson et al.
patent: 4357456 (1982-11-01), Lopez et al.
patent: 4564646 (1986-01-01), Nishigaki et al.
Naturharze, Terpentinoel, Talloel, Chemie und Technologie, pp. 175-185.
Paint Technology 19 (1955) p. 159.
Deutsche Farbenzeitschrift, 9 (1955) p. 463.

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