Radiation-curing compositions

Details Radiation-curing compositions Radiation-curing compositions

2001-02-02

2002-08-20

Dawson, Robert (Department: 1712)

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

Synthetic resins

Compositions to be polymerized by wave energy wherein said...

C427S515000, C556S437000, C556S445000, C556S440000, C525S477000, C525S479000, C528S032000, C528S026000, C528S012000

Reexamination Certificate

active

06437015

ABSTRACT:

The invention relates to radiation-curing compositions comprising
TECHNICAL FIELD
(A) organopolysiloxanes containing (meth)acryloxy groups, and
(B) photosensitizers,
and to their use for preparing coatings which repel tacky substances.
DESCRIPTION OF THE RELATED ART
EP-A 624 627 (Shin-Etsu Chemical Co., Ltd; published on Nov. 17, 1994) describes radiation-curing organopolysiloxane mixtures which comprise &ohgr;-(meth)acryloxyalkyl groups. The organopolysiloxanes present in the mixtures are branched, with the branching sites representing trifunctional monoorganosiloxy groups, known as T units.
U.S. Pat. No. 5,034,419 (Th. Goldschmidt; published on Jul. 23, 1991) describes (meth)acrylate-modified organopolysiloxane mixtures for preparing abhesive coating materials, where two organopolysiloxanes differing in chain length are mixed in different proportions by weight.
WO95/26266 (Mobil Oil Corporation; published on Oct. 5, 1995) describes abhesive coating materials comprising added monomeric or oligomeric organic acrylate esters.
DE-A 44 43 749 (Wacker Chemie GmbH; published on Jun. 13, 1996) discloses organopolysiloxanes containing (meth)acryloxy groups.
SUMMARY OF THE INVENTION
One object was to provide novel compositions based on organopolysiloxanes containing (meth)acryloxy groups which undergo free-radical crosslinking by irradiation, preferably with light. Another object was to provide novel compositions for the preparation of coatings which repel tacky substances. A further object was to provide abhesive coating compositions which give abrasion-resistant coatings, i.e. which adhere to the substrate so that they cannot be separated from the substrate by mechanical influences, for example by rubbing, in order that they are not partially detached, and so reduce the adhesive force of the labels, when carriers located on them which are provided with adhesive, such as labels, for example, are peeled off. Yet another object was to provide abhesive coating compositions which give tack-free, thoroughly cured coatings. These objects are achieved by the invention.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides radiation-curing compositions comprising
(A) linear organopolysiloxanes containing (meth)acryloxy groups, of the general formula
R
1
a
R
3-a
SiO(R
2
SiO)
c
[R
2
Si—Y—SiR
2
O(R
2
SiO)
c
]
d
SiR
3-b
R
1
b
  (I)
in which R can be identical or different and is a monovalent, substituted or unsubstituted hydrocarbon radical having 1 to 18 carbon atoms per radical, which is free from terminal aliphatic carbon—carbon multiple bonds,
R
1
is a radical of the formula
where z is an integer whose value is from 1 to 10,
R
2
is a hydrogen atom or a methyl radical,
R
3
is a linear or branched alkylene radical having 1 to 6 carbon atom(s) per radical, and
R
4
is a linear or branched alkylene radical having 1 to 6 carbon atom(s) per radical,
Y is a divalent organic radical which is free from terminal aliphatic carbon—carbon multiple bonds,
a is 0 or 1,
b is 0 or 1,
with the proviso that the sum a+b per molecule is 1 or 2, on average from 1.3 to 1.9,
c is an integer whose value is from 1 to 1000, and
d is 0 or an integer whose value is from 1 to 10, and
(B) photosensitizers.
The invention additionally provides a process for preparing coatings which repel tacky substances by applying crosslinkable compositions comprising
(A) linear organopolysiloxanes containing (meth)acryloxy groups, of the general formula
R
1
a
R
3-a
SiO(R
2
SiO)
c
[R
2
Si—Y—SiR
2
O(R
2
SiO)
c
]
d
SiR
3-b
R
1
b
  (I)
where R, R
1
, Y, a, b, c and d are as defined above,
with the proviso that the sum a+b per molecule is 1 or 2, on average from 1.3 to 1.9, and
(B) photosensitizers
to the surfaces which are to be made repellent to tacky substances, and then curing the crosslinkable composition by irradiation.
The invention also provides linear organopolysiloxanes containing (meth)acryloxy groups, of the general formula
R
1
a
R
3-a
SiO(R
2
SiO)
c
[R
2
Si—Y—SiR
2
O(R
2
SiO)
c
]
d
SiR
3-b
R
1
b
  (I)
where R, R
1
, Y, a, b, c and d are as defined above,
with the proviso that the sum a+b per molecule is 1 or 2, on average from 1.3 to 1.9.
The invention also provides organopolysiloxanes containing Si-bonded hydrogen atoms, of the general formula
H
a
R
3-a
SiO(R
2
SiO)
c
[R
2
Si—Y—SiR
2
O(R
2
SiO)
c
]
d
SiR
3-b
H
b
  (II)
where R, Y, a, b, c and d are as defined above,
with the proviso that the sum a+b per molecule is 1 or 2, on average from 1.3 to 1.9.
The novel organopolysiloxanes (A) preferably have a viscosity of from 20 to 20,000 mm
2
/s at 25° C., particularly preferably from 20 to 1000 mm
2
/s at 25° C. and, with very particular preference, from 20 to 500 mm
2
/s at 25° C.
The novel organopolysiloxanes preferably have iodine numbers of between 1 and 60, preferably between 4 and 40, the iodine number indicating the amount of iodine, in grams per 100 grams of novel organopolysiloxane employed, which is consumed during addition onto the double bond.
Examples of the radical R are in each case alkyl radicals, such as the methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and the tert-pentyl radical, hexyl radicals, such as the n-hexyl radical, heptyl radicals, such as the n-heptyl radical, octyl radicals, such as the n-octyl radical and isooctyl radicals, such as the 2,2,4-trimethylpentyl and the 2-ethylhexyl radical, nonyl radicals, such as the n-nonyl radical, decyl radicals, such as the n-decyl radical, dodecyl radicals, such as the n-dodecyl radical, tetradecyl radicals, such as the n-tetradecyl radical, hexdecyl radicals, such as the n-hexadecyl radical, and octadecyl radicals, such as the n-octadecyl radical, cylcoalkyl radicals, such as cyclopentyl, cyclohexyl and 4-ethylcyclohexyl radical, cycloheptyl radicals, norbornyl radicals and methylcyclohexyl radicals, aryl radicals, such as the phenyl, biphenyl [sic], naphthyl and anthryl and phenanthryl radical; alkaryl radicals, such as o-, m-, p-tolyl radicals, xylyl radicals and ethylphenyl radicals; aralkyl radicals, such as the benzyl radical, and also the &agr;- and the &bgr;-phenylethyl radical. The radical R is preferably the methyl radical.
Examples of substituted radicals R are haloalkyl radicals, such as the 3,3,3-trifluoro-n-propyl radical, the 2,2,2,2′,2′,2′-hexafluoroisopropyl radical and the heptafluoroisopropyl radical, haloaryl radicals, such as the o-, m- and p-chlorophenyl radical, and alkyl radicals which are substituted by an ether oxygen atom, such as the 2-methoxyethyl and the 2-ethoxyethyl radical.
The radical R
2
is preferably a hydrogen atom.
Examples of radicals R
3
are alkylene radicals of the formula —CH
2
—CH
2
—, —CH
2
—CH
2
—CH
2
—, —C(CH
3
)HCH
2
— and —(CH
2
)
4
—. R
3
is preferably a radical of the formula —CH
2
—CH
2
—.
Examples of alkylene radicals R
4
are those of the formula —CH
2
—, —CH(CH
3
)—, —C(CH
3
)
2
—, —C(CH
3
)(C
2
H
5
)—, —(CH
2
)
2
— and —(CH
2
)
4
—, preference being given to the radical of the formula —CH
2
—.
Examples of radicals R
1
are those of the formula
where z is as defined above and is preferably an integer having a value from 2 to 8.
Y is preferably a divalent hydrocarbon radical which can be interrupted by one or more oxygen atoms. Examples of radicals Y are those of the formula —CH
2
CH
2
—, —CH(CH
3
)—, —(CH
2
)
4
—, —(CH
2
)
5
—, —(CH
2
)
6
—, —(CH
2
)
8
—, —(CH
2
)
10
—, —(CH
2
)
12
—, —(CH
2
)
3
O(CH
2
)
3
—, 1,3-(CH
2
CH
2
)
2
(C
6
H
4
), 1,4-(CH
2
CH
2
)
2
(C
6
H
4
), 1,3-(CH
2
CHCH
3
)
2
(C
6
H
4
) and 1,4-(CH
2
CHCH
3
)
2
(C
6
H
4
), preference being given to the radicals of the formula —CH
2
CH
2
—, —CH(CH
3
)—, —(CH
2
)
6
—, —(CH
2
)
8
—, 1,3-(CH
2
CH
2
)
2
(C
6
H
4
), 1,4-(CH
2
CH
2
)
2
(C
6
H
4
), 1,3-(CH
2
CHCH
3
)
2
(C
6
H
4
) and 1,4-(CH
2
CHCH
3
)
2
(C
6
H
4
) and particular preference to the radical of the formula —CH
2
CH
2
—.
The sum a+b is preferably on average from 1.4 to 1.9.
As end groups th

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