Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1982-04-28
1984-05-22
Wong, Jr., Harry
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526204, C08F12034
Patent
active
044502656
DESCRIPTION:
BRIEF SUMMARY
This invention relates to adhesive compositions containing as the major polymerisable constituent one or more esters of 2-Cyanoacrylic acid, such as Ethyl 2-cyanoacrylate.
The improvement of cyanoacrylate adhesive compositions, particularly as regards the stability of the adhesive bonds formed therewith under exposure to high temperatures and moist conditions, is an area of wide-ranging and energetic research activity. The present invention adds one compound to the list of additive substances known to improve these compositions in the said respect.
There follows a short outline of the closest prior art known to us.
1. Federal German Pat. No. 24 29 070 (1975: Bostik GmbH) discloses the use of Itaconic anhydride as an additive in alkyl and allyl cyanoacrylate compositions to impart improved heat resistance to the adhesive bonds formed.
2. Patent No. 34874 (1972: Loctite (Ireland) Limited) and its equivalent U.S. Pat. No. 3,832,334 disclose the use of Maleic anhydride and derivatives thereof as additives in alkyl cyanoacrylate compositions to impart improved heat resistance to the adhesive bonds formed.
3. Japanese Pat. No. 78 110 635 (1978: Toa Gosei) discloses the use of hydroxyalkyl and hydroxyhaloalkyl esters of .alpha.,.beta.-unsaturated carboxylic acids as additives in alkyl cyanoacrylate compositions to impart improved heat resistance to the adhesive bonds formed.
4. Japanese Pat. No. 77 80 336 (1977: Toa Gosei) discloses the use of dicarboxylic acids and their anhydrides as additives in ethyl cyanoacrylate compositions to impart improved impact resistance to the adhesive bonds formed.
5. Japanese Pat. No. 77 78 933 (1977: Toa Gosei) discloses the use of aromatic polycarboxylic acids and their anhydrides as additives in Ethyl cyanoacrylate compositions to impart improved impact resistance to the adhesive bonds formed.
The above references also provide a good indication of progress up to their respective dates in the improvement of heat and impact resistance in adhesive bonds formed from alkyl cyanoacrylate compositions by the use of additives.
The invention provides an adhesive composition comprising a polymerisable constituent the major part of which comprises at least one ester of 2-cyanoacrylic acid, characterised in that the composition additionally comprises a proportion of Phthalic anhydride effective for favourably influencing the strength and/or durability of adhesive bonds formed from said composition, under exposure to moisture or elevated temperature.
An effective proportion of Phthalic anhydride for the above recited purpose is selected from the range 0.1% to 5.0% by weight of the composition. A preferred proportion is selected from the range 0.3% to 0.7% by weight, a specially preferred proportion being about 0.5% by weight of the composition.
It has been found that an Ethyl cyanoacrylate solution containing 0.5% by weight Phthalic anhydride yields adhesive bonds having a heat resistant superior to that of bonds made with an otherwise identical composition containing 1.0% by weight Maleic anhydride in place of the Phthalic anhydride. Some of the bonds were formed between grit blasted steel lapshears, others between grit blasted aluminium lapshears. The bonds made with the invented composition were also found to possess significantly improved moisture resistance as compared with bonds made with the Maleic anhydride composition. It may be remarked that the Maleic anhydride composition is itself known to outperform a composition containing Ethyl cyanoacrylate alone, in both of the above mentioned respects.
It will be noted that various organic anhydrides have been proposed for the general purpose of the present invention. However none of the prior proposals known to us, either in the art cited aove or elsewhere, embraces the use of Phthalic anhydride. Some of the prior art goes so far as to exclude Phthalic anhydride specifically, indicating perhaps some misconception or prejudice prevalent in the art about the suitability of this compound. Hence the present invention may be said to rest on t
REFERENCES:
patent: 4196271 (1980-04-01), Yamada et al.
patent: 4307216 (1981-12-01), Shiraishi et al.
patent: 4377490 (1983-03-01), Shiraishi et al.
Loctite Corporation
Miller Eugene F.
Wong, Jr. Harry
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