Elastic crosslinked metathesis polymer composition

An elastic crosslinked metathesis polymer composition is disclosed comprised of a copolymer of a norbornene-type compound which metathesis polymerizes to a linear polymer and a norbornene-type compound having a second double bond of similar reactivity which forms a crosslinked polymer, and a hydrocarbon-based extending oil. Norbornene and dicyclopentadiene are typical comonomers. Polymerization is carried out by a RIM or resin injection molding process.

FIELD OF THE INVENTION 
The present invention relates to a novel rubber-like crosslinked molded 
polymer article and a process for producing said article More 
particularly, the invention relates to a rubber-like crosslinked molded 
polymer article produced by the simultaneous metathesis polymerization and 
molding of a metathesis polymerizable monomer having a specific 
composition in the presence of a specific plasticizer, and a process for 
producing said molded article. 
BACKGROUND OF THE INVENTION 
The production of rubber-like polymers has been investigated over the past 
years. Ring-opening metathesis polymerization of cyclopentene yields a 
linear polymer known by a common name of polypentenamer having a structure 
similar to that of poly-1,4-pentadiene, but having slightly lower double 
bond density in the main chain. The polymer has properties to enable the 
use as a general-purpose rubber, as can be supposed from its structure. 
In order to obtain a rubber having characteristic features, a metathesis 
polymer of norbornene, which has high ring strain and is easily 
polymerizable by metathesis polymerization, has been industrially 
produced. Since the glass transition point of poly(norbornene) is higher 
than normal room temperature and slightly lower than 40.degree. C., the 
polymer is not rubbery, but plastic at normal room temperature. However, 
transition to a rubbery state takes place by slight heating of the polymer 
and the use of the polymer as a shape-memory polymer has been suggested to 
take advantage of the transition property. On the other hand, to make the 
polymer useful as a rubber, a rubber processing oil is added to the 
polymer to lower the apparent glass transition point and the polymer is 
crosslinked by conventional vulcanization to obtain a rubber. The rubber 
produced by the above process is used in various applications as a rubber 
having low resilience. 
On the other hand, a process has been proposed to form a molded polymer 
article by using a low cost metathesis polymerizable cycloolefin having 
two metathesis polymerizable cycloolefin groups, for example 
dicyclopentadiene (DCPD), and carrying out the polymerization and molding 
of the cycloolefin in a mold (in one step) with a metathesis 
polymerization catalyst. More particularly, a process has been proposed to 
obtain a molded polymer article, taking advantage of the fact that a 
metathesis polymerization catalyst system is composed of two components, 
i.e. a catalyst component such as a tungsten chloride and an activator 
component such as an alkylaluminum. Two solutions each containing one of 
the above catalyst system components and monomer, are quickly mixed and 
transferred into a mold (for example, U.S. Pat. No. 4,400,340) where 
polymerization and shaping take place. 
Such a process is attractive for producing a crosslinked molded polymer 
article because the molding can be carried out at a high speed 
simultaneously with polymerization, using a low-pressure, relatively 
inexpensive mold. The polydicyclopentadiene produced by this process is 
generally a plastic having a thermal deformation temperature of 90.degree. 
C. or higher. 
SUMMARY OF THE INVENTION 
In accordance with the present invention the above process can be used for 
producing a molded article of a polynorbornene-type rubber without using a 
vulcanization step. More particularly, a plasticized rubber-like molded 
article having crosslinked norbornene units can be produced at a high 
speed in one step by the metathesis polymerization of a proper mixture of 
a cycloolefin which forms a linear polymer, e.g. norbornene, and a 
cycloolefin which forms a polymer having crosslinked structure, e.g. the 
above-mentioned dicyclopentadiene, in the presence of a high-boiling 
liquid hydrocarbon. Accordingly, the present invention is a rubber-like 
crosslinked molded polymer article that comprises 
(a) a metathesis polymer consisting essentially of 
(i) 95-20 mol % of recurring units derived from at least one norbornene 
derivative expressed by the formula 
##STR1## 
wherein R.sub.1 and R.sub.2 are, independently, groups selected from 
hydrogen atoms, halogen atoms, and hydrocarbon groups having a carbon 
number of 3 or less and optionally containing halogen-substitution and 
wherein R.sub.1 is bonded to the ring by a single or a double bond, and 
(ii) 5-80 mol % of recurring units derived from at least one cycloolefin 
having two strained cycloolefin groups and having a metathesis 
polymerizability comparable to that of the norbornene derivative of (i); 
and 
(b) at least one high-boiling liquid hydrocarbon or partially halogenated 
liquid hydrocarbon in an amount sufficient to plasticize said polymer and 
lower its apparent glass transition point to or below normal room 
temperature. 
DETAILED DESCRIPTION OF THE INVENTION 
Additionally, the invention is directed to a process for producing a 
rubber-like crosslinked molded polymer article by carrying out the 
metathesis polymerization and molding of 
(a) a metathesis polymerizable monomer mixture consisting essentially of 
(i) 95-20 mol % of at least one norbornene derivative expressed by the 
formula 
##STR2## 
wherein R.sub.1 and R.sub.2 are, independently, groups selected from 
hydrogen atoms, halogen atoms, and hydrocarbon groups having a carbon 
number of 3 or less and optionally containing halogen-substitution and 
wherein R.sub.1 is bonded to the ring by a single bond or a double bond, 
and 
(ii) 5-80 mol % of at least one cycloolefin having two strained cycloolefin 
groups and having a metathesis polymerizability comparable to that of the 
norbornene derivative of (i) in the presence of 
(b) at least one high-boiling liquid hydrocarbon or partially halogenated 
high-boiling liquid hydrocarbon in an amount sufficient to plasticize the 
polymer produced by the metathesis polymerization of said monomer mixture 
and lower its apparent glass transition point to or below normal 
temperature. 
The vulcanization molding of rubber is a special process which generally 
necessitates a kneading process to incorporate a vulcanizing agent, 
followed by a vulcanization treatment for a relatively long period in a 
heated mold. The present invention, by effecting polymerization, 
crosslinking and molding in a single step makes possible the production of 
a molded rubber article having characteristic rubber properties in one 
step at a high speed. 
The norbornene compound used in the present invention is expressed by the 
following formula 
##STR3## 
wherein R.sub.1 and R.sub.2 are as previously mentioned. The bond between 
the group R.sub.1 and the norbornene ring is shown by ---, which indicates 
that the bond may be a single bond or a double bond. 
Preferred examples of the norbornenes include norbornene (R.sub.1 
.dbd.R.sub.2 .dbd.H) 
5-methylnorbornene (R.sub.1 .dbd.--Ch.sub.3 and R.sub.2 .dbd.H) 
5-ethylnorbornene (R.sub.1 .dbd.--C.sub.2 H.sub.5 and R.sub.2 .dbd.H) 
5-(chloromethyl)norbornene (R.sub.1 .dbd.--CH.sub.2 Cl and R.sub.2 .dbd.H) 
5-(ethylidene)norbornene (R.sub.1 .dbd..dbd.CH--CH.sub.3 and R.sub.2 
.dbd.H) 
5-chloronorbornene (R.sub.1 .dbd.--Cl and R.sub.2 .dbd.H) and 
5,6-dimethylnorbornene (R.sub.1 .dbd.--CH.sub.3 and R.sub.2 
.dbd.--CH.sub.3). 
Among the above compounds, norbornene, 5-methylnorbornene and 
5-ethylidenenorbornene, and, especially, norbornene is preferable taking 
into consideration the availability of raw materials. 
As mentioned above, the groups R.sub.1 and R.sub.2 may be an acyclic olefin 
group having a carbon number of 3 or less except that such a group must be 
attached to the norbornene ring via its double bond, i.e. the group cannot 
be vinyl (--CH.dbd.CH.sub.2) or propenyl (--CH.dbd.CH--CH.sub.3 or 
--CH.sub.2 --C.dbd.CH.sub.2) as these groups act as chain-transfer agents 
to lower the molecular weight of the polymer during metathesis 
polymerization. 
The norbornene compounds can be produced by the Diels-Alder reaction of 
cyclopentadiene with corresponding olefins such as ethylene, propylene, 
butylene, butadiene, pentene-1, allyl chloride, vinyl chloride, butene-(2) 
and the like. Ethylidenenorbornene can also be produced by the 
isomerization of vinylnorbornene which is a Diels-Alder addition product 
of cyclopentadiene and butadiene. Ethylnorbornene can be produced by the 
partial reduction of vinylnorbornene. 
The cycloolefin having two strained cycloolefin groups and having a 
metathesis polymerizability comparable to that of the norbornene compound 
is, for example, a compound containing a norbornene group and a second 
cycloolefin group having a number of ring structure members to cause ring 
strain wherein the strain of the second cycloolefin group is increased by 
the condensation of said group with the norbornene ring or one or more 
other rings between it and the norbornene ring. Typical examples of rings 
having the number of members to cause straining of the ring are the 
4-membered ring and the 5-membered ring, especially the 5-membered ring. 
In other word, the preferred group is composed of a norbornene which is 
further condensed with another ring for example a 4-membered ring or 
5-membered ring, to form a cycloolefin compound having the above two 
strained cycloolefin groups. 
To assist the understanding of the above, an explanation is shown by the 
following simplified formulas. 
The norbornene ring structure (1) of the following formula (i) is a group 
containing a cyclopentene ring condensed with another ring at its 
3,5-sites. 
##STR4## 
The structure (2) of the following formula (ii) is a group containing a 
cyclopentene ring condensed with another ring at its 3,4-sites. 
##STR5## 
The cycloolefin compound to be used in the present invention is a compound 
containing two groups selected from either one or both of the structure 
(1) and (2) expressed by the above formulae (i) and (ii). 
The cycloolefin compound may also have short side chains having a carbon 
number of 1-3 and can, optionally, contain halogen substitution. 
Dicyclopentadiene is especially preferable as such cycloolefin compound 
from the viewpoint of its performance and availability. 
As can be seen from the following formula (iii), dicyclopentadiene contains 
each of the above structures (1) and (2). 
##STR6## 
The cycloolefin compounds also include oligocyclopentadienes having a 
higher degree of condensation than dicyclopentadiene, such as, e.g. 
tricyclopentadiene. These oligocyclopentadienes are generally produced as 
a thermal equilibrium mixture with dicyclopentadiene or by thermal 
polymerization of cyclopentadiene or dicyclopentadiene and, accordingly, 
they may be used as an equilibrium mixture with dicyclopentadiene. The 
cycloolefin compounds further include 
1,4-,5,8-dimethano-1,4,4a,5,8,8a-hexahydrona-ohthalene, 
1,4-,5,8-,9,10-trimethano-1,4,4a,5,8,8a,9,9a,10,10a-decahydroanthracene 
and the like The above cycloolefin compounds are generally used in 
combination with dicyclopentadiene. 
As mentioned before, dicyclopentadiene is especially preferred as the 
cycloolefin compound having metathesis polymerizability comparable to that 
of norbornene. 
The term "liquid" in reference to the high-boiling liquid hydrocarbons or 
partially halogenated compounds used in the present invention means that 
the material is substantially fluid at room temperature or thereabout. 
However, the term "liquid" further includes a material which is solid by 
itself but has extremely high miscibility with the above 
norbornene--cycloolefin copolymer and acts as a plasticizer when mixed 
with the copolymer. 
The term "high-boiling" means that the rate of evaporation of the 
hydrocarbon or partially halogenated hydrocarbon from the rubber-like 
molded polymer article in use is within a practically permissible range. 
The boiling point of the hydrocarbon depends upon the required practical 
conditions and is generally at least 200.degree. C., preferably at least 
250.degree. C., and most preferably at least 300.degree. C. under normal 
pressure. Hydrocarbons having carbon number of 12 or more generally meet 
the above requirement. 
Any kind of hydrocarbons such as paraffinic, naphthenic or aromatic 
hydrOcarbons can be used in the present invention so long as the 
hydrocarbon meets the above conditiOns. Aliphatic substituted aromatic 
compounds or aliphatic substituted alicyclic compounds are generally 
preferred. Aliphatic substituted aromatics are especially preferred. 
Materials commercially available as process oils for oil extension of a 
rubber generally correspond to the above description. Various kinds of 
process oils such as e.g. paraffin-rich oil, naphthene-rich oil, and 
aromatic-rich oil are commercially available products that can be 
employed. 
Materials produced for other purposes which meet the requirements of the 
hydrocarbons of the present invention are also usable in the present 
process. Certain kinds of thermal media and intermediates for synthetic 
detergents are examples of such materials. These materials include, among 
others, triethylbiphenyl, trimethyldiphenylethane, dipropylnaphthalene, 
dodecylbenzene, didodecylbenzene, dodecylnaphthalene and mixtures thereof. 
Partially halogenated hydrocarbons can be used in the present invention 
because of increased polarity, improved affinity with the metathesis 
polymer, increased boiling point and, in some casee, ability to impart 
flame-retardancy depending upon the halogen content. The partially 
halogenated compounds generally mean compounds obtained by substituting a 
portion of the hydrogen atoms in the aliphatic, alicyclic or aromatic 
group by adding halogen to unsaturated bonds in the above compound The 
halogen is generally chlorine or bromine and the halogen content is 
usually 15-75 wt. %, especially 25-55 wt. %. 
Examples of the partially halogenated compounds are chlorinated paraffin, 
chlorinated dodecylbenzene, and brominated dodecylbenzene. 
The above-mentioned norbornenes, cycloolefin compounds, high-boiling liquid 
hydrocarbons or partially halogenated liquid hydrocarbons should have the 
lowest possible content of impurities capable of reacting with the 
components of a metathesis polymerization catalyst system because these 
compounds are present together with the metathesis polymerization catalyst 
system during the metathesis polymerization process. 
The sensitivity to impurities is different between the catalyst component 
and the activator component of the metathesis polymerization catalyst 
system. Accordingly, in the case of the polymerization and molding process 
wherein the catalyst component and the activator component are divided 
into separate solutions that are injected into a mold immediately after 
mixing, the substantial inhibitory action due to impurities can sometimes 
be prevented by adding the process oil to one or the other of the two 
solutions depending upon the kind of impurity existing in the compound and 
which component will be adversely affected by the impurity. 
The ratios of the norbornenes, cycloolefin compounds and hydrocarbons or 
their halogenated compounds or partially halogenated compounds to be used 
in the present invention are essentially as follows. 
The molar ratio of the norbornene compound to the cycloolefin compound is 
from 95:5 to 20:80 as mentioned previously. Since the glass transition 
point of a metathesis copolymer of a norbornene compound and a cycloolefin 
compound is generally normal room temperature or above, the liquid 
hydrocarbon or partially halogenated liquid hydrocarbon is used in an 
amount to reduce the glass transition point to a point not higher than 
normal room temperature and preferably not higher than the lower limit of 
the working temperature range anticipated for the specific rubber-like 
molded polymer article being manufactured. Accordingly, the amount of the 
liquid hydrocarbon or partially halogenated liquid hydrocarbon depends 
upon the specific compound, the monomer composition of the polymer, and 
the working temperature range of the rubber-like molded polymer article. 
Addition of too much of the liquid hydrocarbon, or partially halogenated 
liquid hydrocarbon, sometimes induces blooming of the liquid on the 
surface of the molded articles and causes practical problems. It is 
necessary to select the optimum composition by correlating the kinds and 
amounts of the norbornenes and cycloolefin compounds with the kinds and 
amounts of the liquid hydrocarbons or partially halogenated liquid 
hydrocarbons according to the required working temperature range and the 
properties of the molded article. 
The amount of the cycloolefin compound (e.g. DCPD) in the monomer mixture 
generally has influence upon crosslinking density to exert a remarkable 
effect on the modulus and elongation of a rubber-like elastomer. The kind 
of the norbornene compound has an influence upon the properties of a 
flexible chain segment and, accordingly, upon the modulus, elongation, 
residual strain, and other properties of the elastomer. 
On the other hand, the type of liquid hydrocarbon or partially halogenated 
liquid hydrocarbon has an influence upon the compatibility with the 
copolymer of the norbornene compound and the cycloolefin compound. 
Accordingly, it is necessary to pay attention to the maximum amount of 
addition to keep the mixture from phase-separation and to the coagulation 
temperature of the mixture because the phase-separation and coagulation at 
the lower limit of the working temperature deteriorates the properties of 
the polymer. Furthermore, the resilience or, conversely, the 
vibration-damping property, is also influenced by the composition and 
structure. A molded article rich in ring-structure generally tends to have 
low resilience. 
The optimum composition is selected according to the required properties 
taking the above-mentioned factors into consideration. 
The molar ratio of the norbornene compound to the cycloolefin compound is 
preferably from 80-20 to 40-60 and the concentration of the liquid 
hydrocarbon or the partially halogenated liquid hydrocarbon is 10-60 wt. 
%, more preferably 20-50 wt. % based on the total weight of the metathesis 
polymerizable components plus the high-boiling hydrocarbon components. 
In addition to the above monomers, the composition of the present invention 
may contain other metathesis polymerizable cycloolefin compounds which do 
not meet the description cited above as items (a) (i) and (a) (ii) of the 
main copolymer composition, so long as such compounds have metathesis 
polymerizability comparable to that of norbornene. The other metathesis 
polymerizable cycloolefins must be used in an amount not sufficient to 
deteriorate the properties of the rubber. Examples of the other 
cycloolefin compound are 1,4-,5,8-dimethano-1,4,4a,5, 
6,7,8,8a-octahydronaphthalene, and norbornadiene. 
The recurring unit in the polymer of the present invention derived from the 
norbornene compound has the following structure: 
##STR7## 
wherein R.sub.1 and R.sub.2 are the same groups mentioned before. 
The recurring unit derived from dicyclopentadiene which is cited as an 
example of cycloolefin compounds having two strained cycloolefin groups 
and having a metathesis polymerizability comparable to that of the 
norbornenes in the polymer of the present invention has, for example, the 
structure of the following formulas. 
##STR8## 
The recurring unit derived from a cycloolefin compound other than 
dicyclopentadiene, having two strained cycloolefin groups and having a 
metathesis polymerizability comparable to that of the norbornenes in the 
polymer of the present invention similarly has the structure which can be 
easily determined from the structure of the monomer. 
The polymer of the present invention contains linear segments resulting 
from repeating unite of A and B with periodic crosslinks resulting from 
the structure C and is plasticized with the liquid hydrocarbons or 
partially halogenated liquid hydrocarbons to form a rubber-like molded 
article. 
The catalyst component of the metathesis polymerization catalyst system 
used in the production of the molded polymer article of the present 
inventiOn are salts such as halides of tungsten, rhenium, tantalum, 
molybdenum and the like with tungsten compounds being especially 
preferred. Among tungsten compounds are preferred tungsten halides, 
tungsten oxyhalides and the like. More particularly, tungsten hexachloride 
and tungsten oxychloride, etc., are preferred. However, such tungsten salt 
compounds undesirably initiate cationic polymerization substantially 
immediately when added directly to said monomer. It is, therefore, 
preferable that the tungsten salt compounds be previously suspended in an 
inert solvent such as benzene, toluene or chlorobenzene and solubilized by 
the addition of a small amount of an alcoholic compound or a phenolic 
compound. 
A Lewis base or a chelating agent is preferably added to the catalyst in an 
amount of about 1-5 mol per 1 mol of the tungsten compound in order to 
prevent undesirable polymerization. Those additives may include 
acetylacetone, acetoacetic acid alkyl esters, tetrahydrofuran, 
benzonitrile and the like. 
Following such treatment, the monomer solution (Solution A) containing the 
catalyst component has sufficiently high stability for practical use. 
Ammonium tungstate compounds or ammonium molybdate compounds may also be 
used. These compounds do not require the solubilization treatment or the 
inactivation step as they are substantially less active than the halide 
salts. 
The activator components of the metathesis polymerization catalyst system 
include organo-metallic compounds chiefly comprising alkylated compounds 
of metals of group I--group III in the periodic table, preferably, 
alkylaluminum compounds, alkylaluminum halide compounds and trialkyltin 
hydrides such as diethylaluminum chloride, ethylaluminum dichloride, 
trioctylaluminum, dioctylaluminum iodide and tributyltin hydride. The 
organometallic compound used as the activator component i.e. dissolved in 
the monomer mixture to form a monomer solution containing activator 
component (Solution B). 
According to the present invention, in principle, the molded polymer 
articles are produced by mixing the Solution A with the Solution B. The 
polymerization reaction, however, starts very rapidly when the 
above-mentioned composition is used and, consequently, undesirable 
initiation of hardening often occurs before the mold is completely filled 
with the mixed solution. In order to overcome the problem, it is 
preferable to use a polymerization moderating agent to delay onset of 
polymerization. 
As such moderators are generally used Lewis bases, particularly, ethers, 
esters, nitriles and the like. Examples of the moderators include ethyl 
benzoate, butyl ether, diglyme and the like. Such moderators are generally 
added to the solution containing the activator component comprising 
organometallic compound. When using the ammonium tungstate or molybdenum 
compounds, an alkyl alcohol is generally employed as the moderator. 
When a tungsten compound is used as the catalyst component, the ratio of 
the tungsten compound in the metathesis polymerization catalyst system to 
the above-mentioned monomers is about 1000:1 - about 15000:1, and 
preferably about 2000:1 on molar basis. When an alkyl-aluminum compound is 
used as the activator component, the ratio of the aluminum compound to the 
above-mentioned monomers is about 100:1 - about 2000:1 and preferably 
around a ratio of about 200:1 - about 500:1 on molar basis. The amount of 
the moderator may be adjusted by experiments depending upon the amount of 
the catalyst system. 
In order to decrease the residual monomer content, a small amount of an 
active halogen compound such as trichloromethyltoluene, ethyl 
trichloroacetate, isophthaloyl chloride or an acid anhydride such as 
benzoic anhydride may be added in the production of the rubber-like molded 
polymer article of the present invention. The residual monomer may have 
the action of a plasticizer in the polymer molded article of the present 
invention, however, the content of the residual monomer is preferably as 
low as possible because of the characteristic smell and volatility of 
monomers of the class employed. 
A variety of additives may be used practically in the rubber-like 
crosslinked polymer molded article of the present invention to improve or 
to maintain characteristics of the molded articles. The additives include 
fillers, pigments, antioxidants, light stabilizers, flame retardants, 
macromolecular modifiers and the like. These additives are to be added to 
the starting solutions, since they cannot be added after the solutions are 
polymerized to the crosslinked molded polymer article. 
Additives may be added to either one or both of Solution A and the Solution 
B. The additives should be substantially unreactive with the highly 
reactive catalyst component, activator component and other components of 
the solutions to avoid practical troubles such as an inhibitory action on 
polymerization. If a reaction between the additive and the catalyst 
component or the activator component is unavoidable but does not 
essentially inhibit the polymerization, the additives can be mixed with a 
proper combination of the monomers, the above liquid hydrocarbons or 
partially halogenated liquid hydrocarbons to prepare a third solution, 
which is mixed with the first and second solutions immediately before 
polymerization. When the additive is a solid filler forming gaps which can 
be filled sufficiently with both solutions immediately before or during 
the polymerization reaction, the mold may be filled with the filler prior 
to charging the reactive solutions into the mold. 
The fillers used as additives are preferably those effective in improving 
abrasion resistance and fatigue resistance. They include carbon black, 
fine silica particles and the like. In some cases, the fillers are 
surface-treated e.g. with a so-called silane coupler as required. 
Furthermore, the filler may be a fibrous reinforcing material. Such 
fibrous reinforcing materials include glass fiber, carbon fiber, polyester 
fiber, aramid fiber, nylon fiber and the like. These fibers may be used in 
the form of woven fabric, mat, nonwoven fabric and the like. 
The rubber-like crosslinked molded polymer article used in the present 
invention may also contain an antioxidant. Preferably, a phenolic- or 
amine-antioxidant is added to the solution in advance. Examples of the 
antioxidants include 2,6-t-butyl-p-cresol, 
N,N'-diphenyl-p-phenylenediamine, and tetrakis[methylene- 
(3,5-di-t-butyl-4-hydroxycinnamate)]methane. 
The reactive solutions A and B for the production of the crosslinked molded 
polymer article by the present invention are preferably introduced into 
the mold in the form of laminar flow to prevent the inclusion of bubbles. 
To realize the laminar flow, a proper viscosity corresponding to the 
injection speed is necessary and the addition of a thickener to either one 
or both of Solutions A and B is frequently required. 
The material usable as the above thickener is a polymer which is soluble in 
the monomer or in the liquid hydrocarbon or partially halogenated liquid 
hydrocarbon, is free from inhibitory action to metathesis polymerization, 
does not cause deterioration of the characteristic properties of the 
article and, preferably, imparts desirable properties to the article. The 
polymer usable for the above purpose is preferably a non-crosslinked 
hydrocarbon elastomer such as styrene-butadiene-styrene triblock rubber, 
styrene-isoprene-styrene triblock rubber, polybutadiene, polyisoprene, 
butyl rubber, ethylene-propylene-diene terpolymer and the like. 
As described above, the molded polymer articles of the present invention 
are prepared by simultaneous polymerization and molding The molding method 
includes, as mentioned above, a resin injection process comprising the 
proper mixing of a catalyst, a raw material monomer and a plasticizer or, 
more preferably, mixing of the previously prepared solutions A and B with 
a static mixer or the like and the injection of the produced premix into a 
mold and a RIM process comprising the impingement mixing of the solution A 
and the solution B containing divided catalyst system in a head and the 
immediate injection of the mixture into the mold. The RIM process is used 
in general. 
In both of RIM process and resin injection process, the mixture can be 
introduced into the mold under relatively low pressure, so that an 
inexpensive mold is usable. The temperature in the mold increases rapidly 
by the heat of reaction upon the start of the polymerization reaction in 
the mold, and the polymerization reaction is completed in a short time. 
The molded article of the present invention can be removed easily from the 
mold without using a releasing agent. 
The rubber-like crosslinked molded polymer article of the present invention 
can be produced, as mentioned above, in one step at high speed by the 
simultaneous polymerization and molding of a monomer. 
Conventional molding of a rubber generally necessitates a kneading step to 
blend various additives, including a crosslinker, into a green rubber 
polymer and a separate step to vulcanize and mold the kneaded mixture. The 
molding efficiency is not high compared with conventional molding process 
of plastics. The present invention enables the production of a rubber-like 
molded article from a monomer in one step at high speed. 
For the process of such rubber-like molded article, it is already known 
that a polyurethane rubber can be formed in one step from a prepolymer. 
Since polyurethane elastomer generally necessitates heat-treatment after 
molding, the process of the present invention, requiring no 
heat-treatment, has higher efficiency. The rubber properties of the 
polymer of the present invention are considerably different from those of 
the polyurethane rubber as can be supposed from the difference in 
structures. Although polyurethane is preferable in some uses, the method 
of the present invention is superior for the production of a low-resilient 
and low-hygroscopic hydrocarbon rubber and the product is usable in a wide 
variety of applications making use of these properties. 
The molded articles of the present invention are suitable especially as 
large-sized vibration-damping material or cushioning material having 
complicated shapes. 
Since the rubber-like molded article of the present invention is elastic, 
it can be easily released forcibly from a mold even if the mold has an 
overhang. Thus, an article having complicated shape can be produced by the 
process.

The invention described herein is illustrated in detail by the following 
Examples. These examples are presented solely for explanation and are not 
intended to limit the scope of the invention. 
EXAMPLES 1-10 
Dicyclopentadiene, ethylidenenorbornene and norbornene used in the examples 
were those of commercially available high-purity grades. 
5-Chloronorbornene and 5-methylnorbornene were produced by carrying out the 
Diels-Alder reaction of cyclopentadiene with vinyl chloride and propylene 
respectively in an autoclave and purifying the reaction products by 
distillation. The plasticizers were DUTREX 729HP (aromatic rich) SHELL 
FLEX 371N (napthene rich) and SHELL FLEX 210 (paraffin rich). All of these 
are process oils marketed by Shell Oil Co. These oils were used without 
purification. 
20 Parts by weight of tungsten hexachloride was added to 70 parts by volume 
of anhydrous toluene under nitrogen stream. The obtained mixture was added 
to a solution consisting of 21 parts by weight of nonylphenol and 16 parts 
by volume of toluene to obtain a catalyst solution containing 0.5 M of 
tungsten. The solution was purged with nitrogen overnight to remove the 
hydrogen chloride gas formed by the reaction of tungsten hexachloride and 
nonylphenol. A catalyst solution for polymerization was prepared by adding 
1 part by volume of acetylacetone to 10 parts by volume of the solution 
produced by the above procedure. 
100 Parts by weight of a monomer mixture composed of a purified norbornene 
compound and purified dicyclopentadiene and having a composition shown in 
Table 1 was added with 2 parts by weight of 
methylene-bis-(4-hydroxy-3,5-di-t-butyl benzene) as an oxidation 
stabilizer. The obtained solution was added to the above catalyst solution 
for polymerization in an amount to give a tungsten content of 0.0001 M and 
a dichlorodiphenylmethane content of 0.0075 M. A process oil was added oil 
at a ratio shown in Table 1 to obtain a catalyst component solution 
(Solution A). 
A mixed solution of activator for polymerization was prepared by mixing 
trioctylaluminum, dioctylaluminum iodide and dimethyl ether of ethylene 
glycol at molar ratios of 85:15:100. 
The mixed solution was added to 100 parts by weight of a mixture consisting 
of the purified norbornene compound and the purified dicyclopentadiene in 
an amount to give an aluminum content of 0.003 M and a process oil was 
added to the mixture at a ratio shown in Table 1 to obtain an activator 
component solution (Solution B). 
The mixing ratios of the mixture of the purified norbornene compound and 
the purified dicyclopentadiene are shown in Table 1. 
A molded block of a metathesis polymerized crosslinked polymer having 
dimensions of 60 mm x 60 mm and a thickness of about 40 mm was produced 
from the above-prepared solution A and solution B with a small reaction 
injection molding machine. The liquid temperature and the mold temperature 
in the injection were 30.degree. C. and 70.degree. C., respectively. 
Right circular cylindrical specimens having thickness of 12.70.+-.0.13 mm 
and diameter of 29.0 mm were cut from the above molded product and the 
compression set of each specimen was measured under the heat-treatment 
condition of 70 1.degree. C. and 22 hours in accordance with JIS K6301. 
The results are also shown in Table 1. 
The Table 1 shows that the rubber-like molded articles produced from a 
monomer in one step at high speed using the solutions having the 
compositions of Examples 1-10 have small residual strain caused by 
compression under heating and that the articles can be used in a state 
subjected to static compression or shearing force. 
Comparison of the Examples 1, 4 and 5 shows that the hardness of the 
obtained rubber-like molded article decreases by increasing the content of 
the high-boiling liquid hydrocarbon. Accordingly, the hardness of the 
rubber-like molded article can be arbitrarily selected. 
The resilience of the molded article is highly dependent upon the kind of 
the high-boiling liquid hydrocarbon. Comparison of the Examples 1, 7 and 9 
shows that the resilience decreases in the order DUTREX 729HP, SHELL FLEX 
371N and SHELL FLEX 210. This decrease corresponds to decreasing cyclic 
structure content in the oils. 
It is clear from the above results that a variety of crosslinked 
rubber-like molded articles can be produced in one step at high speed by 
varying the ratio of a norbornene compound and a cycloolefin compound 
having two strained cycloolefin groups to control the crosslinking density 
and by varying the type of the high-boiling liquid hydrocarbon or 
partially hydrogenated liquid hydrocarbon to be used in the process. 
TABLE 1 
__________________________________________________________________________ 
Example No. 
1 2 3 4 5 
__________________________________________________________________________ 
Norbornene Norbornene 
Norbornene 
Ethylidene- 
Norbornene Norbornene 
Compound* 80 40 norbornene 
80 80 
(mol %) 70 
Cycloolefin compound 
Dicyclo- Dicyclo- Dicyclo- Dicyclo- Dicyclo- 
having 2 strained 
pentadiene 
pentadiene 
pentadiene 
pentadiene pentadiene 
cycloolefin groups* 
20 60 30 20 20 
(mol %) 
High-boiling liquid 
DUTREX 729 HP 
DUTREX 729 HP 
DUTREX 729 HP 
DUTREX 729 HP 
DUTREX 729 HP 
hydrocarbon** 
30 30 30 50 70 
(wt. %) 
Permanent set (%)*** 
26 38 27 35 36 
Norbornene Norbornene 
Norbornene 
5-Chloro Norbornene 5-Methyl 
Compound* 50 80 norbornene 
80 norbornene 
(mol %) 60 50 
Cycloolefin compound 
Dicyclo- Dicyclo- Dicyclo- Dicyclo- Dicyclo- 
having 2 strained 
pentadiene 
pentadiene 
pentadiene 
pentadiene pentadiene 
cycloolefin groups* 
40 20 40 20 50 
(mol %) Cyclopenta- 
diene Trimer 
10 
High-boiling liquid 
DUTREX 729 HP 
SHELL FLEX 210 
SHELL FLEX 210 
SHELL FLEX 371N 
SHELL FLEX 371N 
hydrocarbon** 
70 30 30 30 30 
(wt. %) 
Permanent set (%)*** 
27 24 20 26 29 
__________________________________________________________________________ 
*Molar ratio of each compound based on 100 mol of the sum of the 
norbornene compound and the cycloolefin compound having two strained 
cycloolefin groups. 
**Weight % of the highboiling liquid hydrocarbon based on 100 parts by 
weight of the sum of the norbornene compound, the cycloolefin compound 
having two strained cycloolefin groups and the highboiling liquid 
hydrocarbon. 
***Measured in accordance with JIS K 6301: Heattreatment condition, at 
70.degree. C. for 22 hours.