Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2001-12-24
2004-06-15
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...
C522S148000, C522S150000, C522S151000, C522S155000, C522S157000, C522S158000, C522S160000, C526S258000, C526S265000, C526S266000, C526S270000, C526S256000, C526S348700
Reexamination Certificate
active
06750267
ABSTRACT:
BACKGROUND OF THE INVENTION
Hydrocarbon polymers which contain reactive functional groups suitable for crosslinking are known in the art. For example, polymers having a terminal hydroxy group can be reacted with a compound such as an allyl halide, an acrylic acid, an oxirane ring-containing compound having carbon-carbon double bonds, or an isocyanate compound containing a carbon-carbon double bonds to form a polymer having a crosslinkable end groups.
U.S. Pat. Nos. 6,054,549, 6,069,185 and 6,242,058 disclose a two step method of preparing polyisobutylene with reactive end-groups. The method involves first preparing an alkoxysilyl-functionalized polyisobutylene. Then the polyisobutylene is reacted with an alkenyl ether in the presence of a transesterification catalyst to form a polyisobutylene with vinyl ether end-groups.
In another approach, allylic functionality on polyisobutylene can be converted to hydroxyl by a hydroboration-oxidation sequence. This two-stage process employs treatment of the polymer with diborane or 9-borabicyclo{3.3.1}nonane (9-BBN), followed by reaction with hydrogen peroxide, to convert carbon to carbon double bonds to alcohol-containing groups. Hydroboration with diborane results in some secondary hydroxyl formation, whereas 9-BBN is highly regioselective and gives only primary alcohols. Thus, this technique may be used to prepare a polyisobutylene polymer having at least one end group of the formula —CH
2
CH
2
CH
2
OH. This hydroxyl group can, in turn, be reacted with, e.g., acryloyl chloride to provide a polymer having an acrylate end group of the formula:
Unlike polymers which contain vinylic unsaturation, vinyl ethers and acrylic-functional polymers are desirable since they can be readily cured (i.e., crosslinked) by exposure to ultraviolet (UV) radiation when formulated with a photoinitiator. They therefore find utility in coating, ink and paint applications. However, the hydroboration of allyl-functional polyisobutylene is difficult because, in addition to being quite expensive, the boranes are flammable and react violently with water.
Therefore, there is a need for radiation curable compounds and methods of forming radiation curable compounds that is cost effective and overcomes or minimizes the above problems.
SUMMARY OF THE INVENTION
It has been discovered that a crosslinked polymer can be prepared from a composition containing a cationic photoinitiator and a radiation-curable polymer having the composition represented by Structural Formula I:
In Structural Formula I, A is a substituted or unsubstituted hydrocarbon. Preferably, A is phenyl or t-butylphenyl. R is a polymer chain. Preferably, R is a polymer chain that can be formed by cationic polymerization, such as poly(isobutylene). Z
1
is selected form —O—, —S— and —NR
7
—. Preferably, Z
1
is —O— or —S—. D is selected from —H or, alternatively, D is a group represented by Structural Formula II:
In Structural Formula II, Z
2
is selected from —O—, —S— and —NR
8
—. Preferably, Z
2
is —O— or —S—. More preferably, Z
2
is the same as Z
1
and is —O— or —S—. R
1
and R
2
for each occurrence are, independently, selected from the group consisting of —H, —OR
5
, —NR
5
R
6
, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, and a substituted or unsubstituted heterocycloalkyl. Preferably, R
1
and R
2
for each occurrence are —H. R
4
is selected from a substituted or unsubstituted alkylene, a substituted or unsubstituted cycloalkylene, a substituted or unsubstituted heteroalkylene, and a substituted or unsubstituted heterocycloalkylene. Preferably, R
4
is an alkylene group, such as methylene or an dimethylmethylene. R
5
and R
6
are each, independently, selected from the group consisting of —H, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, and a substituted or unsubstituted heterocycloalkyl. Alternatively, R
5
and R
6
together with the nitrogen to which they are attached form a substituted or unsubstituted heterocycloalkyl. R
7
and R
8
are each, independently, selected from the group consisting of —H, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, and a substituted or unsubstituted heterocycloalkyl. t and w are each independently 0 or an integer from 1-5. Preferably, both t and w are 0. y and z are each, independently, a positive integer. Preferably, z is a positive integer from 1-5. More preferably, z is 1.
The cationic photoinitiator of the composition is preferably an onium salt, a diaryliodonium salt of sulfonic acid, a triarylsulfonium salt of sulfonic acid, a diaryliodonium salt of boric acid, and a triarylsulfonium salt of boric acid.
The composition can be cured to form a crosslinked polymer by exposing the mixture to radiation of sufficient energy for sufficient time to cause at least 5% of the heterocyclic end groups to crosslink. In a preferred embodiment, the mixture is exposed to sufficient energy for sufficient time to cause at least 50% of the heterocyclic end groups. In a more preferred embodiment, the mixture is exposed to sufficient energy for sufficient time to cause at least 80% of the heterocyclic end groups.
In one embodiment a radiation-curable polymer can be represented by Structural Formula III:
In Structural Formula III, A, R, Z
1
, Z
2
, R
1
, R
2
, R
4
, t, w, y and z are defined as above.
The present invention further relates to a method of making an article of manufacture. The article of manufacture is made by applying a radiation-curable composition that contains a radiation-curable polymer represented by Structural Formula I and a cationic photoinitiator, to a solid substrate to form a coating. The coating is then exposed to an energy source such as ultraviolet light or visible light in an amount sufficient to cure the coating.
Radiation-curable polymers of the invention can be prepared by contacting under reaction conditions a cationically polymerizable monomer with a cationic polymerization catalyst to produce a living polymer. The living polymer is then reacted with an end capping compound represented by Structural Formula IV:
In Structural Formula IV, Z
1
, R
1
, and t are defined as above. R
3
is —Sn(R
18
)
3
, —Si(R
18
)
3
or —D. Thus, radiation-curable polymers of the present invention can be prepared in a one-pot synthesis.
The heterocyclic end groups of radiation-curable polymers represented by Structural Formula I or III generally react rapidly in the presence of a cationic photoinitiator and radiation to form covalent bonds with other heterocyclic end groups. Radiation curing is advantageous because it is relatively low cost, easy to maintain and has low potential hazard to industrial users. In addition, curing times are much shorter than other curing methods, and heat-sensitive materials can be safely coated and cured under visible or ultraviolet (UV) light where thermal energy might damage the substrate. Thus, compositions containing one or more radiation-curable polymers represented by Structural Formula I or III are useful in forming coatings or adhesives.
DETAILED DESCRIPTION OF THE INVENTION
The term “crosslinked polymer” refers to a polymer network in which covalent bonds have been formed between polymer chains.
A radiation-curable polymer is a polymer that can be crosslinked by exposure to radiation.
A hydrocarbon is moiety that primarily contains carbons and hydrogens.
The term “polymer chain,” as used herein, refers to polymers chains, oligomers chains and copolymers chains which can be either linear or branched. A polymer chain is prepared from one or more monomer, wherein each monomer reacts with growing polymer chain to form a polymer chain composed of a repeating monomer unit. Typically, a polymer chain of the invention has between about 5 and about 10,000 repeat units. In one embodiment, the polymer chain has at least 30 repeat units. More preferably, the polymer chain will have between about 50 and about 1000 repeat units. One or more different monomers may be used to form the polymer chain. Preferred polymer chains
Bahadur Maneesh
Faust Rudolf
Hadjikyriacou Savvas
Suzuki Toshio
Berman Susan W
Hamilton Brook Smith & Reynolds P.C.
University of Massachusetts Lowell
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