Novel radiation-curable organopolysiloxane compound and coating method

A novel organopolysiloxane compound is proposed which has, in a molecule, at least three (meth)acryloxy groups localized at only one of the molecular chain ends of the polysiloxane chain. By virtue of the localization of the (meth)acryloxy groups, the organopolysiloxane compound is highly curable by the irradiation with a radiation, e.g., electron beams and ultraviolet light, to give a cured coating film on a substrate surface exhibiting excellent releasability against sticky substances. A synthetic route for the preparation of such a one-end crosslinkable organopolysiloxane compound is described.

BACKGROUND OF THE INVENTION 
The present invention relates to a novel radiation curable or crosslinkable 
organopolysiloxane compound or, more particularly, to a novel 
radiation-curable or crosslinkable organopolysiloxane compound which is 
suitable to form a cured surface film on a substrate surface having 
releasability against adhesives or sticky substances and useful as a 
back-surface treatment agent of pressure-sensitive adhesive tapes or 
surface treatment agent of release paper for pressure-sensitive adhesive 
labels and the like, hereinafter referred to as a surface-releasing agent, 
as well as to a method for the preparation of such a novel 
organopolysiloxane compound. 
The invention also relates to a method for forming a surface-releasing film 
on the surface of a substrate by using the organopolysiloxane compound. 
It is well known that a variety of organopolysiloxanes or compositions 
thereof are used in the application as a surface-releasing agent, of which 
organopolysiloxanes having two or more of (meth)acryloxy, i.e. acryloxy or 
methacryloxy, groups in a molecule are widely used as a radiationcurable 
surface-releasing agent by virtue of their crosslinkability by the 
irradiation with electron beams. 
Such a (meth)acryloxy-containing organopolysiloxane has a problem that the 
surface-releasability against adhesive materials is necessarily decreased 
when the density of the (meth)acryloxy groups therein is increased with an 
object to obtain improved radiation-crosslinkability. This disadvantage 
can be partly overcome by admixing the (meth)acryloxycontaining 
organopolysiloxane with a dimethylpolysiloxane of a straightly linear 
molecular structure having a high molecular weight but no 
radiation-crosslinkability (see, for example, Japanese Patent Kokai No. 
62-30234). Though not ineffective in improving the surface releasability, 
such an organopolysiloxane composition has a problem that the coating film 
produced by the electron beam irradiation of low dose is poor in respect 
of the residual adhesiveness. Alternatively, a proposal has been made in 
Japanese Patent Kokai No. 62-11914 for the use of an organopolysiloxane 
having (meth)acryloxy groups bonded only to the silicon atoms at the 
molecular chain ends as a coating agent of optical fibers. Such an 
organopolysiloxane, however, is not quite satisfactory as a 
surface-releasing agent due to the relatively poor releasability 
characteristics when a coating film thereof is cured by the irradiation 
with radiations. 
SUMMARY OF THE INVENTION 
The present invention accordingly has an object to provide a novel 
organopolysiloxane which is radiationcurable to give a surface-releasing 
coating film having a good balance between the radiation-crosslinkability 
and the surface-releasing characteristics without the above described 
problems and disadvantages in the prior art organopolysiloxanes or 
compositions thereof. 
Thus, the organopolysiloxane compound unexpectedly discovered in the course 
of the investigations conducted with the above mentioned object is a novel 
compound represented by the general formula 
EQU R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n --SiR.sub.2 --(CH.sub.2).sub.m 
--Si(R).sub.a (A).sub.3-a, . . . (I) 
in which each R is, independently from the others, a monovalent hydrocarbon 
group, A ;s a group having at least one (meth)acryloxy group of the 
formula H.sub.2 C=CR.sup.1 --CO--O--, R.sup.1 being a hydrogen atom or a 
methyl group, the subscript is a positive integer in the range from 4 to 
101, the subscript m ;s a positive integer in the range from 1 to 5 and 
the subscript a is zero, 1 or 2, the total number of the (meth)acryloxy 
groups in the (3 - a) groups denoted by A being at least three. Namely, 
the organopolysiloxane, which is a novel compound not known in the prior 
art nor described in any literatures, is characteristic in the feature 
that each molecule thereof has at least three (meth)acryloxy groups 
localized as bonded to the silicon atom at only one of the molecular chain 
ends. 
The method of the invention for forming a surface-releasing film on the 
surface of a substrate comprises: (a) coating the substrate surface with 
the above defined organopolysiloxane to form a coating film; and (b) 
irradiating the coating film with radiation such as electron beams and 
ultraviolet light to cure the organopolysiloxane. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As is described above, the organopolysiloxane compound of the present 
invention is characteristic by the feature that each molecule thereof has 
at least three (meth)acryloxy groups localized as bonded to the silicon 
atom at only one of the molecular chain ends. As a consequence of the thus 
localized distribution of the (meth)acryloxy groups in the molecule, the 
organopolysiloxane is highly crosslinkable and cured by the irradiation 
with a relatively small dose of radiation or, in particular, electron 
beams and the cured coating film has excellent surface releasability 
despite the high sensitivity to radiation-induced crosslinking. This is in 
great contrast to conventional (meth)acryloxy group-containing 
organopolysiloxanes in which the (meth)acryloxy groups are distributed at 
random as the pendant groups on the polysiloxane structure or bonded to 
both of the terminal silicon atoms to have a disadvantage that 
simultaneous improvements can hardly be obtained in both of the 
radiation-curability of the compound and the surface-releasability of the 
radiation cured coating film. 
As is mentioned above, the organopolysiloxane of the invention must have at 
least three (meth)acryloxy groups bonded to only one of the terminal 
silicon atoms in the molecular chain of the organopolysiloxane. When the 
total number of the (meth)acryloxy groups is smaller than 3, the 
organopolysiloxane would have somewhat decreased radiation-curability even 
when they are bonded to only one of the terminal silicon atoms. 
The organopolysiloxane compound of the invention is represented by the 
general formula 
EQU R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n --SiR.sub.2 --(CH.sub.2).sub.m 
--Si(R).sub.a (A).sub.3-a. (I) 
In the formula, each R is, independently from the others, a monovalent 
hydrocarbon group free from aliphatic unsaturation selected from the class 
consisting of alkyl groups, e.g., methyl, ethyl, propyl and butyl groups, 
and aryl groups, e.g., phenyl and tolyl groups, as well as those 
substituted monovalent hydrocarbon groups obtained by replacing a part or 
all of the above named hydrocarbon groups with, for example, halogen 
atoms, cyano groups and the like exemplified by chloromethyl, 
3,3,3-trifluoropropyl and 2-cyanoethyl groups. It is preferable that at 
least 80% in number of the groups denoted by R in a molecule are methyl 
groups in respect of the high surface-releasability of the cured film 
formed from the organopolysiloxane. The symbol A in the formula is a group 
having at least one (meth)acryloxy group of the formula H.sub.2 C=CR.sup.1 
--CO--O--, R.sup.1 being a hydrogen atom or a methyl group. The subscript 
n is a positive integer in the range from 4 to 101. When the value of n is 
too small, the radiation-cured coating film of the compound only has low 
surface releasability while, when the value of n is too large, the 
radiation-curability of the compound is somewhat decreased. Though not 
particularly limitative, the subscript m in the formula is a positive 
integer in the range from 1 to 5 in respect of the simple synthetic 
procedure described later. The subscript a in the formula is zero. 1 or 2 
satisfying the requirement that the total number of the (meth)acryloxy 
groups in the (3-a) groups denoted by the symbol A is at least three. For 
example, the value of a must be zero when each of the groups denoted by A 
has only one (meth)acryloxy group. 
Following are the examples of the structural formulas expressing the 
organopolysiloxane compounds represented by the general formula (1) and in 
conformity with the definitions of each of the symbols and subscripts: 
R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n --SiR.sub.2 --(CH.sub.2).sub.2 
--Si(O--Si--C.sub.3 H.sub.6 --Q) .sub.3 ; 
R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n --SiR.sub.2 --(CH.sub.2).sub.2 
--Si(O--Si--CH.sub.2 --Q).sub.3 ; 
R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n --SiR.sub.2 --(CH.sub.2).sub.2 
--SiR[O--CH(CH.sub.2 --Q).sub.2 ].sub.2 ; 
R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n --SiR.sub.2 --(CH.sub.2).sub.2 
--SiR[O--CH.sub.2 --C(CH.sub.2 --Q) .sub.3 ].sub.2 ; 
R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n --SiR.sub.2 --(CH.sub.2).sub.2 
--Si[O--CH(CH.sub.2 --Q).sub.2 ].sub.3 ; and 
R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n --SiR.sub.2 --(CH.sub.2).sub.2 
--Si[O--CH.sub.2 --C(CH.sub.2 --Q) .sub.3 ].sub.3 ; 
in which each of the groups denoted by Q in a molecule can be, 
independently from the others, an acryloxy group or a methacryloxy group. 
Following is a description of the synthetic procedure for the preparation 
of the inventive organopolysiloxane compound represented by the general 
formula (1). In the first place, a hexaorgano cyclotrisiloxane, e.g., 
hexamethyl cyclotrisiloxane, is subjected to a ring-opening polymerization 
reaction with a triorganosilanol, e.g., trimethyl silanol, as the 
chain-stopper agent in the presence of a penta-coordinate organosilicon 
compound such as the compound expressed by the following formula 
##STR1## 
as a catalyst so as to give a linear diorganopolysiloxane blocked at only 
one of the molecular chain ends with a silanolic hydroxy group and 
represented by the general formula 
EQU R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n-1 --SiR.sub.2 --OH,(II) 
in which R and n each have the same meaning as defined above. 
The second step is the dehydrochlorination reaction of the above obtained 
one-end OH-blocked diorganopolysiloxane of the general formula (II) with a 
diorganochlorosilane, e.g., dimethyl chlorosilane, of the general formula 
R.sub.2 HSiCl, R being the same as above, in the presence of an acid 
acceptor such as triethyl amine to give an SiH-terminated 
diorganopolysiloxane represented by the general formula 
EQU R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n --SiR.sub.2 --H. (III) 
The next step is the addition reaction or the so called hydrosilation 
reaction between the above obtained one end SiH-terminated 
diorganopolysiloxane of the general formula (III) and an alkenyl 
containing or, preferably, a vinyl group-containing organosilane compound 
represented by the general formula 
EQU CH.sub.2 .dbd.CH--(CH.sub.2).sub.m-2 Si(R).sub.a (X).sub.3-a,(IV) 
in which R, m and a each have the same meaning as defined above, m being 
preferably equal to 2, and X is a halogen or, preferably, chlorine atom or 
an alkoxy group, e.g., methoxy and ethoxy groups, in the presence of a 
platinum compound as the catalyst to give a one-end SiX terminated 
diorganopolysiloxane represented by the general formula 
EQU R.sub.3 Si--O--(--SiR.sub.2 --O--).sub.n --SiR.sub.2 --(CH.sub.2).sub.m 
Si(R).sub.a (X).sub.3-a. (IV) 
The last step of the synthetic process to give the organopolysiloxane of 
the general formula (I) is the dehydrohalogenation reaction, when X is a 
halogen atom, or dealcoholation condensation reaction, when X is an alkoxy 
group, with a compound having at least one (meth)acryloxy group and one 
hydroxy group simultaneously in a molecule in the presence of a suitable 
acceptor for the hydrogen halide or catalyst for the dealcoholation 
reaction. Examples of such a (meth)acryloxy- and hydroxy-containing 
compound include those expressed by the following structural formulas, in 
which the symbol Me is a methyl group: 
Q--C.sub.3 H.sub.6 --SiMe.sub.2 --OH; 
Q--CH.sub.2 --SiMe.sub.2 --OH; 
Q--CH.sub.2 --CH(OH)--CH.sub.2 --Q; and 
HO--CH.sub.2 --C(CH.sub.2 --Q).sub.3, 
in which each of the groups denoted by Q in a moleculae can be, 
independently from the others when a molecule has two or more of the 
groups Q, an acryloxy group or a methacryloxy group. Needless to say, the 
type of the (meth)acryloxy- and hydroxy-containing compound must be 
selected in consideration of the value of the subscript a in the general 
formula (IV) in order to satisfy the requirement that the resulting 
organopolysiloxane of the general formula (I) should have at least three 
(meth)acryloxy groups. 
As is mentioned before, the inventive organopolysiloxane compound of the 
general formula (I) obtained in the above described manner has excellent 
radiation-curability with a relatively small dose of electron beams to 
give a cured surface film having excellent surface releasability against 
adhesives or sticky substances so that the compound as such can be used as 
a surface releasing agent for the back surface of pressure-sensitive 
adhesive tapes or a surface-releasing agent of release paper on 
pressure-sensitive adhesive labels or stickers for temporary protection. 
The inventive compound can be easily cured by the irradiation with a 
radiation such as electron beams, .gamma.-rays and X-rays as well as 
ultraviolet light. When the radiation is ultraviolet light, in particular, 
it is desirable that the inventive organopolysiloxane compound is admixed 
with a photopolymerization initiator such as acetophenone, benzophenone, 
4-chlorobenzophenone, 4,4 -dimethoxy benzophenone, 4-methyl acetophenone, 
benzoin methyl ether, benzoin trialkylsilyl ethers and the like. The 
amount of the photopolymerization initiator is preferably in the range 
from 0.5 to 15% by weight based on the organopolysiloxane of the general 
formula (I). 
The organopolysiloxane of the present invention can be used as such as a 
radiation-curable surface releasing agent to be applied to the substrate 
surface. It is optional according to need that the surface-releasing agent 
is prepared by admixing the inventive organopolysiloxane with various 
kinds of additives such as levelling agents, antistatic agents, defoaming 
agents, coloring agents and the like. If necessary to facilitate the 
coating work with the surface-releasing agent, it can optionally be 
diluted with a suitable organic solvent. The surface-releasing agent of 
the inventive organopolysiloxane is applicable to the surface of any 
substrate materials such as paper, plastic films, metal foils and the 
like. The thickness of coating is usually in the range from 0.1 to 200 
.mu.m but naturally depends on the sticking power of the adhesive or 
sticky substance against which the surface-releasing treatment is 
undertaken. The coating machine used in the coating work is not 
particularly limitative including bar coaters, gravure coaters, reverse 
coaters, rod coaters, offset printing machines and the like. The thus 
formed coating film of the inventive organopolysiloxane can be readily 
cured to exhibit excellent surface releasability by the irradiation with a 
radiation such as electron beams and ultraviolet light. When electron 
beams are used as the radiation, complete cure of the organopolysiloxane 
can be achieved with a dose of, for example, 0.3 Mrad or larger. 
In the following, the invention is described in more detail by way of 
examples including a description of the typical process for the 
preparation of the organopolysiloxane and application thereof as a 
surface-releasing agent making a comparison with conventional 
organopolysiloxanes. In the following description, the term of "parts" 
always refers to "parts by weight" and the values of viscosity are all 
those obtained by the measurement at 25.degree. C. The effectiveness of 
the surface releasing treatment with the organopolysiloxanes was evaluated 
in terms of the peeling resistance and the residual adhesiveness 
determined by the following procedures. 
Peeling resistance 
A specified pressure-sensitive adhesive tape (Lumirar 31B Tape, a product 
by Nitto Denko Co., Japan) was applied and bonded to the surface of a 
substrate after the surface-releasing treatment and kept for 72 hours at 
70.degree. C. under a load of 20 g/cm.sup.3 and the adhesive tape was then 
peeled off at 25.degree. C. by pulling in the 180.degree. direction using 
an automatic tensile tester at a pulling velocity of 30 cm/minute to 
record the resistance against peeling in g per 5 cm width of the tape. 
Residual adhesiveness 
The value of the residual adhesiveness was given as a % ratio of the value 
of peeling resistance determined by peeling an adhesive tape, which was 
taken by peeling off from the release-treated substrate surface in the 
above described peeling resistance test and then applied and bonded to a 
well-polished clean stainless steel plate, off the stainless steel plate 
to the value of peeling resistance determined in just the same manner as 
above excepting replacement of the release-treated substrate with a clean 
Teflon plate. A larger value of this residual adhesiveness means a smaller 
fraction of uncured organopolysiloxane in the surface-releasing coating 
film which may migrate from the release-treated substrate surface to the 
pressure-sensitive adhesive tape to decrease the adhesiveness of the tape. 
In other words, the value of residual adhesiveness can be used as a 
measure of the curability of the organopolysiloxane. 
Synthetic Preparation 1 
Into a four-necked glass flask of 1 liter capacity were introduced 666 g (3 
moles) of hexamethyl cyclotrisiloxane, 90 g (1 mole) of trimethyl silanol 
and 0.1 g of a pentacoordinate organosilicon compound expressed by the 
formula 
##STR2## 
as a catalyst to form a reaction mixture, which was heated at 80.degree. 
C. for 16 hours under agitation to effect the ring-opening polymerization 
reaction of the cyclic trisiloxane. The product was a one-end silanol 
terminated dimethyl polysiloxane having an average degree of 
polymerization of 10 and expressed by the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.9 --H, (1) 
in which Me is a methyl group. 
In the next place, the thus obtained one-end silanolterminated dimethyl 
polysiloxane was admixed with 120 g of triethyl amine and then 94.5 g (1.0 
mole) of dimethyl monochlorosilane were added dropwise to the mixture in 
the flask, which was agitated for 5 hours at 25.degree. C. The product was 
a one-end SiH-terminated dimethyl polysiloxane having an average degree of 
polymerization of 11 expressed by the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.9 --SiMe.sub.2 --H,(2) 
in which Me is a methyl group. 
Then, 162.8 g (0.2 mole) of the one-end SiH-terminated dimethyl 
polysiloxane of the formula (2), 32.3 g (0.2 mole) of vinyl 
trichlorosilane, 200 g of toluene and 0.1 g of a 2% solution of 
chloroplatinic acid in n butyl alcohol were introduced into a four-necked 
flask of 500 ml capacity and the mixture was heated at 100.degree. C. for 
5 hours under agitation to effect the hydrosilation reaction. The reaction 
mixture was examined by the infrared absorption spectrophotometry which 
indicated complete disappearance of the absorption band at the wave number 
of 2150 cm .sup.-1 assignable to the Si-H bond. The product was a dimethyl 
polysiloxane blocked at one molecular chain end with a trichlorosilylethyl 
group and expressed by the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.9 --SiMe.sub.2 --C.sub.2 H.sub.4 
--SiCl.sub.3, (3) 
in which Me is a methyl group. 
In the last step of the synthetic procedure, 97.6 g (0.1 mole) of the above 
obtained one end trichlorosilylethyl-terminated dimethyl polysiloxane of 
the formula (3). 89.4 g (0.3 mole) of pentaerithritol triacrylate, 187 g 
of toluene, 88.2 g of triethyl amine and 0.08 g of di-tertbutyl 
hydroxytoluene were introduced into a four-necked flask of 500 ml capacity 
and the mixture was heated at 70.degree. C. for 3 hours under agitation to 
effect the dehydrochlorination reaction. The precipitates of triethylamine 
hydrochloride were removed from the reaction mixture by filtration and the 
filtrate was stripped of the volatile matter including the solvent by 
heating under reduced pressure to give 140 g of a clear, light yellow 
liquid product having a viscosity of 120 centipoise. This product, 
referred to as the polysiloxane A hereinbelow, could be assumed to be 
expressed by the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.8 --SiMe.sub.2 --C.sub.2 H.sub.4 
----Si[O--CH.sub.2 --C(CH.sub.2 --O--CO--CH.dbd.CH.sub.2).sub.3 
].sub.3,(4) 
having nine acryloxy groups localized at one molecular chain end. 
Synthetic Preparation 2 
The synthetic procedure was substantially the same as in Synthetic 
Preparation 1 described above excepting replacement of the pentaerithritol 
triacrylate with the same molar amount, i.e. 64.2 g, of glycerin 
1-methacrylate 3-acrylate of the formula 
EQU CH.sub.2 .dbd.CMe--CO--O--CH.sub.2 --CH(OH)--CH.sub.2 
--O--CO--CH.dbd.CH.sub.2 
to give 128 g of a clear, light yellow liquid product having a viscosity of 
85 centipoise. This product, referred to as the polysiloxane B 
hereinbelow, could be assumed to be expressed by the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.9 --SiMe.sub.2 --C.sub.2 H.sub.4 
----Si[O--CH(CH.sub.2 --O--CO--CH.dbd.CH.sub.2)(CH.sub.2 
--O--CO--CMe.dbd.CH.sub.2)].sub.3, (5) 
having three acryloxy and three methacryloxy groups localized at one 
molecular chain end. 
Synthetic preparation 3 
A one-end SiH-terminated dimethyl polysiloxane expressed by the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.30 --SiMe.sub.2 --H,(6) 
was prepared in substantially the same manner as in the preparation of the 
dimethyl polysiloxane of the formula (2) in Synthetic Preparation 1 
excepting modification of the proportion of the hexamethyl 
cyclotrisiloxane and trimethyl silanol. Then, 236.8 g (0.1 mole) of this 
dimethyl polysiloxane and 16.2 g (0.1 mole) of vinyl trichlorosilane were 
subjected to the hydrosilation reaction in the same manner as in the 
preparation of the dimethyl polysiloxane of the formula (3) to give a 
one-end trichlorosilyl ethyl-terminated dimethyl polysiloxane expressed by 
the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.30 --SiMe.sub.2 --C.sub.2 H.sub.4 
--SiCl.sub.3. (7) 
In the last step, 253 g (0.1 mole) of the thus obtained dimethyl 
polysiloxane of the formula (7) and 89.4 g (0.3 mole) of pentaerithritol 
triacrylate were subjected to the dehydrochlorination reaction with 
triethyl amine as the acid acceptor in the same manner as in Synthetic 
Preparation 1 to give 250 g of a clear, light yellow liquid product having 
a viscosity of 90 centipoise. This product, referred to as the 
polysiloxane C hereinbelow, could be assumed to be expressed by the 
formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.30 --SiMe.sub.2 --C.sub.2 H.sub.4 
----Si[O--CH.sub.2 --C(CH.sub.2 --O--CO--CH.dbd.CH.sub.2).sub.3 
].sub.3,(8) 
having nine acryloxy groups localized at one molecular chain end. 
Synthetic Preparation 4 
A one-end SiH terminated dimethyl polysiloxane expressed by the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.60 --SiMe.sub.2 --H,(9) 
was prepared in substantially the same manner as in the preparation of the 
dimethyl polysiloxane of the formula (2) in Synthetic Preparation 1 
excepting modification of the proportion of the hexamethyl 
cyclotrisiloxane and trimethyl silanol. Then, 229.4 g (0.05 mole) of this 
dimethyl polysiloxane and 7.1 g (0.05 mole) of vinyl methyl dichlorosilane 
were subjected to the hydrosilation reaction in the same manner as in the 
preparation of the dimethyl polysiloxane of the formula (3) to give a 
one-end methyldichlorosilyl ethyl-terminated dimethyl polysiloxane 
expressed by the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.60 --SiMe.sub.2 --C.sub.2 H.sub.4 
--SiMeCl.sub.2. (10) 
In the last step, 236.5 g (0.05 mole) of the thus obtained dimethyl 
polysiloxane of the formula (10) and 21.4 g (0.1 mole) of glycerin 
1-methacrylate 3-acrylate were subjected to the dehydrochlorination 
reaction with triethyl amine as the acid acceptor in the same manner as in 
Synthetic Preparation 1 to give 205 g of a clear, light yellow liquid 
product having a viscosity of 120 centipoise. This product, referred to as 
the polysiloxane D hereinbelow, could be assumed to be expressed by the 
formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.60 --SiMe.sub.2 --C.sub.2 H.sub.4 
----SiMe[O--CH(CH.sub.2 --O--CO--CH.dbd.CH.sub.2)(CH.sub.2 
--O--CO--CMe.dbd.CH.sub.2)].sub.2, (11) 
having two acryloxy and two methacryloxy groups localized at one molecular 
chain end. 
Synthetic Preparation 5 (Comparative) 
A hydrosilation reaction was conducted in substantially the same manner as 
in Synthetic Example 1 between 236.8 g (0.1 mole) of the one end 
SiH-terminated dimethyl polysiloxane prepared in Synthetic Preparation 3 
and expressed by the formula (6) and 12.05 g (0.1 mole) of dimethyl vinyl 
chlorosilane to give a one end dimethylchlorosilyl ethyl-terminated 
dimethyl polysiloxane expressed by the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.30 --SiMe.sub.2 --C.sub.2 H.sub.4 
--SiMe.sub.2 Cl. (12) 
Then, 124 g (0.05 mole) of this dimethyl polysiloxane and 10.7 g (0.05 
mole) of glycerin 1-methacrylate 3-acrylate were subjected to the 
dehydrochlorination reaction in the same manner as in Synthetic 
Preparation 2 to give 98 g of a clear, light yellow product having a 
viscosity of 80 centipoise. This product, referred to as the polysiloxane 
E hereinbelow, could be assumed to be expressed by the formula 
EQU Me.sub.3 Si--O--(--SiMe.sub.2 --O--).sub.60 --SiMe.sub.2 --C.sub.2 H.sub.4 
----SiMe.sub.2 [O--CH(CH.sub.2 --O--CO--CH.dbd.CH.sub.2)(CH.sub.2 
--O--CO--CMe.dbd.CH.sub.2)], (13) 
having each one of acryloxy and methacryloxy groups localized at one 
molecular chain end.

APPLICATION EXAMPLE 1 
A sheet of polyethylene-laminated paper was coated on the polyethylene 
surface with the polysiloxane A obtained in Synthetic Preparation 1 in a 
coating amount of 0.8 g/m.sup.2 using an offset printing machine and the 
coating film was irradiated with electron beams in a dose of 0.5 Mrad in 
an atmosphere of nitrogen gas using a low energy electron accelerator 
(Electrocurtain Model CB20d 50/30, a product by Energy Science Industry 
Co.) to find that the coating film was completely cured to firmly adhere 
to the substrate surface. 
The thus formed cured coating film on the substrate surface was subjected 
to the tests of the peeling resistance and residual adhesiveness in the 
testing procedures described before using a pressure sensitive adhesive 
tape Lumirar 31B (a product by Nitto Denko Co.) to find that the peeling 
resistance was 28 g/5 cm and the residual adhesiveness was 100%. 
APPLICATION EXAMPLE 2 
The experimental procedure was substantially the same as in Application 
Example 1 described above except that the polysiloxane A was admixed with 
4% by weight of benzoin isobutyl ether as a photopolymerization initiator 
and the coating film on the substrate surface in a coating amount of about 
2.0 g/m.sup.2 was irradiated, instead of the electron beam irradiation, in 
air for about 0.6 second with ultraviolet light using two high-pressure 
mercury lamps each having a linear output of 80 watts/cm and held at a 
distance of 8 cm above the substrate surface. The thus formed completely 
cured coating film on the substrate surface was subjected to the same 
tests as above to find that the peeling resistance was 20 g/5 cm and the 
residual adhesiveness was 95%. 
APPLICATION EXAMPLE 3 
The experimental procedure was just the same as in Application Example 1 
excepting replacement of the polysiloxane A with the polysiloxane B 
prepared in Synthetic Preparation 2. The coating film could also be 
completely cured and the tests undertaken with the thus cured coating film 
gave results of a peeling resistance of 30 g/5 cm and a residual 
adhesiveness of 100%. 
APPLICATION EXAMPLES 4 AND 5 
The experimental procedure in each of the experiments was just the same as 
in Application Example 1 excepting replacement of the polysiloxane A with 
the polysiloxane C prepared in Synthetic Preparation 3 and the 
polysiloxane D prepared in Synthetic preparation 4, respectively, to find 
that the dose of the electron beam irradiation required for complete 
curing of the coating films was 3 Mrad and 5 Mrad for the polysiloxanes C 
and D, respectively. The peeling resistance and residual adhesiveness were 
12 g/5 cm and 98% for the polysiloxane C and 5 g/5 cm and 90% for the 
polysiloxane D. 
APPLICATION EXAMPLE 6 (COMATIVE) 
The same experimental procedure as in Application Example 1 was undertaken 
excepting replacement of the polysiloxane A with the polysiloxane E 
prepared in Synthetic Preparation 5 to find that the coating film could 
not be cured even by increasing the dose of the electron beam irradiation 
up to 8 Mrad indicating that this polysiloxane E could not be used 
practically as an electron beam-curable coating agent.