Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2000-03-10
2001-09-18
Berman, Susan W. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S099000, C522S100000, C522S104000, C522S148000, C522S168000, C522S170000, C522S181000, C522S182000, C528S012000, C528S013000, C528S019000, C528S021000, C528S023000, C528S033000, C528S408000, C528S421000
Reexamination Certificate
active
06291540
ABSTRACT:
The present invention relates to a novel process for preparing non-toxic resins which can be crosslinked under irradiation in the presence of an initiator system. These resins are prepared from compositions comprising monomers, oligomers and/or polymers containing organofunctional groups, and are crosslinked in the presence of an initiator system consisting of an onium salt of very low toxicity.
The novel resins according to the invention are used for preparing non-toxic inks, non-toxic, non-stick or anti-adhesive coatings and for preparing articles consisting of a solid support, at least one surface of which is made non-stick or anti-adhesive by coating using the said irradiation-crosslinkable resins, in particular by photochemical activation or by activation with a beam of electrons.
Onium salts or salts of organometallic complexes are well known as cationic polymerization photoinitiators for monomers or polymers containing functional groups of epoxide and vinyl ether type. Many documents describe these photoinitiators and their use: U.S. Pat. Nos. 4,069,054; 4,450,360; 4,576,999; 4,640,967; CA 1,274,646; EP-A-203,829.
However, most of these initiator salts of the prior art are difficult to handle and also present risks of toxicity, which thus limits their field of application, and in particular the use of the crosslinked resins obtained in the presence of these initiators in applications associated with the food industry, such as the wrapping and coating of plastics and metals in particular, for food packaging.
The Applicant has prepared a novel process for preparing resins which are free of risk of toxicity, this process using carefully selected novel initiators which do not have the drawbacks of the prior art, in particular as regards toxicity, thus making it possible to use the said initiators in applications that demand virtually no toxicity. Thus, novel resins have been developed to allow their use in applications associated with the food industry, such as wrapping, and the coating of plastics and metals. These novel resins are prepared from compositions comprising monomers, oligomers and/or polymers containing organofunctional groups, which can be crosslinked under irradiation in the presence of an initiator system; this initiator system is a non-toxic onium salt whose cationic structure is of the formula:
[(CH(CH
3
)
2
-(&PHgr;-)-I—(—R
1
)]
+
(I)
in which the symbol R
1
represents a radical -&phgr;-R
2
, R
2
being a linear or branched alkyl radical comprising from 1 to 20 carbon atoms, preferably 1 to 15 carbon atoms and &PHgr; respresents a phenyl group.
Preferably, the cationic structure of the onium salt is of the formula [(CH(CH
3
)
2
-&PHgr;-)-I-&PHgr;-CH
3
]
+
. The reason for this is that the best results have been obtained with this structure, which unites both a very low level of toxicity and optimum activity during the crosslinking of the crosslinkable compositions.
The anionic structure of the onium salt is chosen from the group consisting of Cl
−
, Br
−
, BF
4
−
, PF
6
−
, CF
3
SO
3
−
, N(SO
2
CF
3
)
2
−
, C(SO
2
CF
3
)
2
−
, B(C
6
F
5
)
4
−
, B(PhOCF
3
)
4
−
, SbF
6
−
and/or AsF
6
−
. However, the following initiators have been found to be particularly suitable in the preparation of non-toxic coatings and/or varnishes:
[CH
3
-&PHgr;-I-&PHgr;-CH(CH
3
)
2
]
+
Cl
−
,
[CH
3
-&PHgr;-I-&PHgr;-CH(CH
3
)
2
]
+
B(C
6
F
5
)
4
−
,
[CH
3
-&PHgr;-I-&PHgr;-CH(CH
3
)
2
]
+
PF
6
−
, and
[CH
3
-&PHgr;-I-&PHgr;-CH(CH
3
)
2
]
+
B(PhOCF
3
)
4
−
.
The crosslinking can be carried out in the presence of various types of irradiation, including heat irradiation. In general, in the context of the presence invention, this crosslinking is carried out under ultraviolet (UV) irradiation and/or under irradiation with an electron beam (E.B.).
Advantageously, the initiators are used in solution in an organic solvent (accelerator), preferably chosen from proton donors and, even more preferably, from the following groups: isopropyl alcohols, benzyl alcohols, diacetone alcohol, butyl lactate and a mixture thereof.
The initiators developed and used in the context of the present invention can be prepared by exchange reaction between a salt of the cationic species, for example a halide (chloride, iodide), a hexafluorophosphate, a tetrafluoroborate or a tosylate with an alkali metal (sodium, lithium or potassium) salt of the anionic species.
The operating conditions, in particular the respective amounts of reagents, the choice of solvents, duration, temperature and stirring, are chosen to allow the initiator according to the invention to be recovered in solid form by filtration of the precipitate formed, or in oily form by extraction with a suitable solvent.
The alkali metal salts of the anionic species can be prepared in a known manner, by exchange reaction between a haloboron compound and an organometallic compound (for example: organomagnesium, organolithium or organotin reagent) bearing the desired hydrocarbon-based groups, in stoichiometric amount, optionally followed by hydrolysis using an aqueous solution of alkali metal halide; this type of synthesis is described, for example, in “J. of Organometallic Chemistry” vol 178, pp. 1-4, 1979; “J.A.C.S” 82, 1960, 5298; “Anal. Chem. Acta” 44, 1969, 175-183; U.S. Pat. No. 4,139,681 and DE-A-2,901,367; “Zh. Org. Khim.” Vol.25, No. 5—pages 1099-1102, May 1989.
The tests carried out to measure the toxicity of the initiators are the Ames test and the LLNA sensitization test. The Ames test makes it possible to measure the mutagenic power of the initiator and the LLNA sensitization test makes it possible to detect the sensitizing power of the initiator. The cytotoxicity of the initiators can also be detected in this latter test (see examples).
The monomers and polymers which can be used in the context of the invention for preparing resins from crosslinkable compositions, in accordance with the invention, are very varied in nature. In the context of the invention, the tests were carried out with monomers and polymers of organic nature or of silicone nature.
Among the monomers and polymers of silicone nature, the polymers defined below are used in the context of the invention. These polymers are polyorganosiloxanes containing functional groups of epoxy and/or vinyl ether type.
The said polyorganosiloxanes are linear or substantially linear and consist of units of formula (II) ending with units of formula (III), or are cyclic and consist of units or formula (II) represented below:
in which
the symbols R
3
are identical or different and represent:
a linear or branched alkyl radical containing 1 to 8 carbon atoms, optionally substituted with at least one halogen, preferably fluorine, the alkyl radicals preferably being methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl,
a cycloalkyl radical containing between 5 and 8 carbon atoms, as a ring which is optionally substituted,
an aryl radical containing between 6 and 12 carbon atoms which may be substituted, preferably phenyl or dichlorophenyl,
an aralkyl portion with an alkyl portion containing between 5 and 14 carbon atoms and an aryl portion containing between 6 and 12 carbon atoms, optionally substituted on the aryl portion with halogens, alkyls and/or alkoxys containing 1 to 3 carbon atoms,
the symbols Y are identical or different and represent:
the group R
3
, a hydrogen radical and/or an organofunctional group which can undergo cationic crosslinking, preferably an epoxyfunctional and/or vinyloxyfunctional group linked to the silicon of the polyorganosiloxane via a divalent radical containing from 2 to 20 carbon atoms and which can contain at least one hetero atom, preferably oxygen, and
at least one of the symbols Y representing an organofunctional group which can undergo cationic crosslinking.
Preferably, at least one of the symbols R
3
of the polyorganosiloxanes used in the compositions according to t
Priou Christian
Richard Jacques
Berman Susan W.
Burns Doane Swecker & Mathis L.L.P.
Rhodia Chimie
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