Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Patent
1984-02-15
1986-02-11
Marquis, Melvyn I.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
524861, 528 15, 528 18, 528 19, 528 31, 528 33, 528 34, 528901, C08G 7706
Patent
active
045699801
DESCRIPTION:
BRIEF SUMMARY
FIELD OF ART
The present invention relates to releasable film forming compositions. More particularly, it is concerned with releasable film forming compositions which exhibit a superior printability, a stable releasability from adhesive materials and a reduced slipperiness.
It has already been well known that condensation reaction type and addition reaction type curable organopolysiloxane compositions, when cured on the surface of base materials such as synthetic resin films, natural and synthetic fibers, glass cloth and aluminum, form a cured film and thereby impart to the base materials a releasability from adhesive materials. Those organopolysiloxane compositions have widely been used for labels, tapes, processing and wrapping papers.
However, those compositions are inferior in printability and very slippery although they are highly releasable. More particularly, in the case where an adhesive sheet or tape is manufactured using any of such organopolysiloxane compositions, drawbacks are encountered such as, for example, a poor printability of the surface coated with the organopolysiloxane composition, repellency against printing ink or felt pen ink (quick drying ink), and impossibility of printing or writing. In many cases, an adhesive sheet or tape is in a rolled form for convenience of its use, so the adhesive-applied layer on one side of a base material of the sheet or tape and the releasing layer formed on the opposite side of the base material of the sheet or tape and the releasing layer formed on the opposite side of the base material by a curable organopolysiloxane composition of the aforementioned type are in contact with each other in an overlapped manner. This is also true of the case where the organopolysiloxane composition is applied to a sheet or tape as a base material and overlaid with an adhesive. Such an adhesive sheet is in many cases printed before use. But, because of a poor printability of the releasing layer surface, it has heretofore been necessary to dispose a wood free paper or the like superior in printability between the adhesive layer and the back of the base sheet material. Moreover, in the case of using such adhesive tape for the packing of corrugated boards or the like, it has been impossible to write receiver's address, etc. on the tape. Further, corrugated boards after packing with such adhesive tape easily slip out of place because the tape surface is very slippery.
It is the object of the present invention to overcome the above-mentioned drawbacks of the prior art. More particularly, the object of the present invention is to provide releasable film forming compositions which exhibit a superior printability, a stable releasability from adhesive materials and a reduced slipperiness, and a process for preparing such compositions.
DISCLOSURE OF THE INVENTION
A first composition of the present invention is a releasable film forming composition comprising:
(1) 100 parts by weight of a substantially straight-chain organopolysiloxane having hydroxyl groups at the ends of the molecular chain and having a viscosity not lower than 1,000 centipoise at 25.degree. C.;
(2) 5 to 80 parts by weight of a finely divided silica;
(3) 2 to 40 parts by weight of a phenyl-containing organosilane or organopolysiloxane represented by the general formula ##STR1## wherein R.sup.1 and R.sup.2 are each a monovalent hydrocarbon group, at least 25 mole % of R.sup.1 and R.sup.2 being phenyl, and n is a number of 1 to 100;
(4) 0.5 to 40 parts by weight of an organohydrogenpolysiloxane having at least three SiH groups per molecule;
(5) a catalytic amount of a metallic salt of an organic acid; and
(6) a desired amount of an organic solvent.
A second composition of the present invention is a releasable film forming composition comprising:
(1) 100 parts by weight of a substantially straight-chain organopolysiloxane containing at least two silicon atom-bonded alkenyl groups per molecule and having a viscosity not lower than 1,000 centipoise at 25.degree. C.;
(2) 5 to 80 parts by weight of a finely divide
REFERENCES:
patent: 3127363 (1964-03-01), Nitzsche et al.
patent: 4176093 (1979-11-01), Zoch
patent: 4461851 (1984-07-01), Hashimoto
Kaiya Nobuo
Sasaki Shosaku
Marquis Melvyn I.
Toray Silicone Company Limited
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