摘要:
A novel method is disclosed for the preparation of a (meth)acryloxyalkyl group-containing organopolysiloxane having a linear structure by the ring-opening siloxane rearrangement polymerization reaction of a (meth)acryloxyalkyl group-containing cyclic organopolysiloxane oligomer either alone or in combination with a cyclic organopolysiloxane oligomer having no (meth)acryloxyalkyl groups. Different from conventional acidic catalyst, the reaction can be promoted by the use of a cation-exchange resin in the H.sup.+ form which can be readily removed from the polymerization mixture after completion of the polymerization reaction leaving no acidic matter which influences on the stability of the product. The catalytic efficiency of the cation-exchange resin can be further enhanced when the resin is, prior to contacting with the cyclic organopolysiloxane oligomer(s), impregnated or swollen with a polar organic solvent such as tetrahydrofuran.
摘要:
A radiation-curable, releasing silicone composition which comprises an organopolysiloxane having methacrylic or acrylic functional groups and represented by the following general formula ##STR1## In the formula, A represents a monovalent hydrocarbon group having a methacrylic or acrylic moiety, R's independently represent an unsubstituted or substituted monovalent organic group, a is an integer of 1, 2 or 3, b is an integer of 2 or 3, and n is an integer of 1 or over. The organopolysiloxane has a viscosity of from 50 to 2,000 cps., at 25.degree. C. The composition exhibits good releasing properties with respect to self-adhesives.
摘要:
A radiation curable organopolysiloxane-containing composition is disclosed which is curable by the irradiation with actinic rays in a relatively low dose to give a cured layer having excellent surface-releasability so that the composition is useful, for example, as a coating agent of release paper for temporary protection of adhesive surface. The composition comprises (a) 0.1 to 20 parts by weight of a linear organopolysiloxane having at least one vinylphenyl or isopropenylphenyl group bonded to only one of the terminal silicon atoms in the molecular chain and (b) 99.9 to 80 parts by weight of a (meth)acrylate compound which is a (meth)acrylic acid ester of a polyhydric alcohol or a polyester of a polyhydric alcohol and a dibasic carboxylic acid esterified with (meth)acrylic acid at the residual hydroxy groups.
摘要:
An organohydrogenpolysiloxane comprising at least two structural units of —(HR1SiO)a— wherein R1 is a monovalent hydrocarbon group, and a is an integer of 2-50, which are connected together via a SiH-free structural unit, is a novel crosslinking agent. A silicone composition comprising an alkenyl-containing organopolysiloxane, the organohydrogenpolysiloxane, and a catalyst is curable through addition reaction, adherent to plastic substrates, and useful for coating purposes.
摘要:
A silicone composition comprising an epoxy-containing organopolysiloxane and a fluoroalkylfluorophosphoric acid salt as a photoacid generator is curable and safe.
摘要:
A solvent-free silicone composition for release paper, comprising: (A) an organopolysiloxane represented by the following average compositional formula (1) (B) an organopolysiloxane represented by the following average compositional formula (2) (C) an organopolysiloxane having alkenyl groups only at its ends, represented by the following formula (3) and (D) an organohydrogenpolysiloxane represented by the following formula (4) wherein the component (A) is contained in an amount of from 10 to 30 wt %, the component (B) is contained in an amount of from 10 to 30 wt %, the component (C) is contained in an amount of from 40 to 80 wt %, based on a total weight of the components (A), (B) and (C), and the component (D) is contained in such an amount that a molar ratio of the hydrogen atom or atoms bonded to a silicon atom to a total of the alkenyl groups of the components (A), (B) and (C) ranges from 1.0 to 4.0. The composition forms a tight release layer whose release force largely increases with release speed.
摘要:
A release film comprising a plastic film substrate 3, a first layer 1 provided on at least one side of the substrate, and a second layer 2 provided on the first layer 1. The second layer 2 functions as a release layer and the first layer 1 as an adhesive layer to fix the second layer 2 on the substrate 3. The release film has a small peel force and can be prepared from solvent-free compositions.
摘要:
Provided by the invention is an ultraviolet-curable silicone-based releasing agent suitable for use as a coating agent on the back surface of a pressure-sensitive adhesive tape and releasable protective sheet on a pressure-sensitive adhesive label with an advantage that the coating layer thereof is curable by ultraviolet irradiation in an atmosphere which is not completely free from oxygen having an inhibiting effect on the curing reaction of the coating layer contributing to cost reduction for the production of pressure-sensitive adhesive tapes and labels. The releasing composition comprises, in addition to a radical-polymerizable organopolysiloxane having (meth)acryloxyalkyl groups and a photopolymerization initiator, a tertiary amine compound such as isoamyl 4-dimethylamino benzoate and 2-ethylhexyl 4-dimethylamino benzoate in a limited amount.
摘要:
A solventless curable silicone release composition contains (A) a branched organopolysiloxane having a vinyl group attached to a silicon atom at an end of its molecular chain, (B) an organohydrogenpolysiloxane having at least three SiH groups in a molecule, and (C) a platinum group metal catalyst. The composition is easily applicable to a thin gage and cures into a releasable silicone coating ensuring light release at high speeds. A release sheet having the cured coating formed thereon has improved release characteristics.
摘要:
Proposed is an improved radiation-curable organopolysiloxane composition capable of giving a cured surface film on a substrate surface which exhibits excellent releasability against sticky substances. The composition is obtained by combining two kinds of (meth)acryloxyalkyl-containing organopolysiloxanes in a specified weight proportion, of which one has a relatively large degree of polymerization but contains only a relatively small amount of the silicon-bonded (meth)acryloxyalkyl groups while the other has a relatively small degree of polymerization but contains a relatively large amount of the silicon-bonded (meth)acryloxyalkyl groups. By virtue of this unique formulation, the surface-release sheet provided with a cured surface film of this organopolysiloxane composition and attached to a sticky surface for temporary protection is safe from generation of a peeling noise which is unavoidable in the prior art when a surface-release sheet is peeled off from the sticky surface at a high peeling velocity, especially, when the peeling resistance is great.