JP7775579B2 - Method for producing modified cycloolefin polymer - Google Patents

Description

The present invention relates to a method for producing a modified cycloolefin copolymer.

A known method for producing reactive cycloolefin polymers with introduced vinylidene groups involves melting the cycloolefin polymer and heating it in a batch-type glass reactor at 330-380°C to cause thermal decomposition (see Patent Document 1).

JP 2014-105280 A

However, the method described in Patent Document 1 has the problem that it is difficult to produce a modified cycloolefin polymer that is little colored.
An object of the present invention is to provide a production method by which a modified cycloolefin polymer with little coloring can be obtained.

The present inventors have conducted research to achieve the above object and have arrived at the present invention.
That is, the present invention is a method for producing a modified cycloolefin polymer having a carbon-carbon double bond, which method comprises a thermal degradation step of heating a cycloolefin polymer to 200 to 450°C in a tubular continuous reactor, and the residence time of the cycloolefin polymer in the tubular continuous reactor in the thermal degradation step is 0.5 to 10 hours.

The method for producing modified cycloolefin polymers of the present invention can produce modified cycloolefin polymers with little coloration.

The method for producing a modified cycloolefin polymer of the present invention is a method for producing a modified cycloolefin polymer having a carbon-carbon double bond, and includes a thermal degradation step in which the cycloolefin polymer is heated to 200 to 450°C in a tubular continuous reactor, and the residence time of the cycloolefin polymer in the tubular continuous reactor during the thermal degradation step is 0.5 to 10 hours.

<Cycloolefin polymer>
The cycloolefin polymer in the present invention is preferably a saturated polymer obtained by ring-opening metathesis polymerization of a cycloalkene having a norbornene skeleton by a known method, followed by complete hydrogenation of the double bonds in the polymer (hereinafter referred to as hydrogenation).

Examples of cycloalkenes having a norbornene skeleton [sometimes referred to as cycloalkenes in the present invention] include monocycloalkenes having a norbornene skeleton and 7 to 25 carbon atoms {norbornene (bicyclo[2.2.1]-2-heptene), tricyclo[4.3.0.1 ^2,5 ]-3-decene, 8-ethyl-tetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]-3-dodecene, tetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]-3-dodecene, pentacyclo[6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ]-4-pentadecene, pentacyclo[7.4.0.1 ^2,5 . 1 ^9,12 . 0 ^8,13 ]-3-pentadecene, pentacyclo[8.4.0.1 ^2,5 . 1 ^9,12 . ^{0 8,13} ]-3-hexadecene, pentacyclo[6.6.1.1 ^3,6 . 0 ^2,7 . 0 ^9,14 ]-4-hexadecene, hexacyclo[6.6.1.1 ^3,6 . 1 ^10,13 . 0 ^2,7 . 0 ^9,14 ]-4-heptadecene, heptacyclo[8.7.0.1 ^2,9 . 1 ^4,7 . 1 ^11,17 . 0 ^3,8 . 0 ^12,16 ]-5-eicosene, heptacyclo[8.7.0.1 ^3,6 . 1 ^10,17 . 1 ^12,15 . 0 ^2,7 . 0 ^11,16 ]-4-eicosene, heptacyclo[8.8.0.1 ^2,9 . ^{1 4,7 .} 1 ^11,18 . 0 ^3,8 . 0 12,17 ]-5-heneicosene, octacyclo[8.8.0.1 ^2,9 . 1 ^4,7 . 1 ^11,18 . 1 ^13,16 . 0 ^3,8 . 0 ^12,17 ]-5-docosene, and nonacyclo[10.9.1.1 ^4,7 . 1 ^13,20 . 1 ^15,18 . 0 ^2,10 . 0 ^3,8 . 0 ^12,21 . 0 ^14,19 ]-5-pentacosene, and the like.

Of the above cycloalkenes, tricyclo[4.3.0.1 ^2,5 ]-3-decene and 8-ethyl-tetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]-3-dodecene are preferred.

In the production method of the present invention, the cycloolefin polymer heated in the tubular continuous reactor in the thermal degradation step is preferably a cycloolefin polymer having one type of cycloalkene as a constituent monomer.

The number average molecular weight of the cycloolefin polymer used in the production method of the present invention is preferably 800 to 200,000, and more preferably 1,000 to 100,000, from the viewpoint of being able to achieve a viscosity that can be handled in a tubular continuous reactor during the thermal degradation step.

Cycloolefin polymers used in the production method of the present invention may be commercially available products (e.g., the Zeonex series and Zeonor series manufactured by Zeon Corporation).

The number average molecular weight of the cycloolefin polymer and modified cycloolefin polymer can be obtained by gel permeation chromatography (GPC) under the following conditions.
Apparatus: "HLC-8120" [manufactured by Tosoh Corporation]
Column: Two "TSKgel GMHXL" columns (manufactured by Tosoh Corporation) and one "TSKgel Multipore HXL-M" column (manufactured by Tosoh Corporation) were connected together. Sample solution: 0.3% by weight of orthodichlorobenzene solution. Solution injection volume: 100 μL.
Flow rate: 1 ml/min Measurement temperature: 135°C Detector: Refractive index detector Reference material: Standard polystyrene (TSK standard POLYSTYRENE)
12 points (molecular weight: 500, 1,050, 2,800, 5,970, 9,100, 18,100, 37,900, 96,400, 190,000, 355,000, 1,090,000, 2,890,000) [manufactured by Tosoh Corporation]

<Modified cycloolefin polymer having carbon-carbon double bonds>
The production method of the present invention is a method for producing a modified cycloolefin polymer having a carbon-carbon double bond, and the bonds of the cycloolefin polymer molecule are cleaved by the thermal degradation step described below, resulting in the generation of a carbon-carbon double bond. That is, by carrying out the thermal degradation step described below, a modified cycloolefin polymer having a carbon-carbon double bond can be produced.
In the present invention, a reaction in which intramolecular bonds are broken by heating is called thermal degradation.

The modified cycloolefin polymer obtained by the production method of the present invention is preferably a modified cycloolefin polymer having 0.1 to 20 (preferably 1 to 10, more preferably 2 to 7) double bonds per 1000 carbon atoms constituting the modified cycloolefin polymer.
When the double bonds of the modified cycloolefin polymer obtained by the production method of the present invention are within this range, the modified cycloolefin polymer can be preferably used to modify various polymers and as a raw material for producing functional polymers.
The number of double bonds can be measured by nuclear magnetic resonance spectroscopy (NMR).

The production method of the present invention is a method for producing a modified cycloolefin polymer having double bonds, and includes a thermal degradation step in which the cycloolefin polymer is heated in a tubular continuous reactor.

The tubular reactor used in the thermal degradation step is a reactor equipped with a raw material inlet through which the raw material cycloolefin polymer is introduced into the reaction section, a reaction section in which the raw material is heated to carry out thermal degradation, and a reactant outlet separate from the inlet, and is preferably further equipped with a heating device and a stirring device.
The continuous reactor means an apparatus in which the raw materials are introduced into the reactor, and then the reactants are successively or continuously discharged from a reactant outlet while the raw materials are successively or continuously introduced into the reactor from a raw material inlet so that the inside of the tubular continuous reactor does not become empty, thereby carrying out a reaction.

The reaction section is not particularly limited in shape as long as it is tubular (or may be cylindrical), and may be a rectangular tube or a cylinder, with a cylindrical shape being preferred from the viewpoint of uniform progress of thermal degradation, etc. Furthermore, from the viewpoint of ease of control, such as uniform progress of thermal degradation, the ratio of the length to the inner diameter of the cylinder (L/D) is preferably 150 to 1500, more preferably 200 to 1200.
The positions of the inlet and outlet of the tubular continuous reactor are not particularly limited, but they are preferably arranged so that the reactants move in one direction within the reaction section from the inlet to the outlet, and it is more preferable that the inlet is arranged at one end of the cylindrical reaction section and the outlet is arranged at another end of the cylinder.

It is preferable that the tubular continuous reactor used in the thermal degradation process is further equipped with a heating device and a stirring device.

The heating device for the tubular continuous reactor may be a device that heats the outer wall of the reaction section, or a device that directly heats the contents inside the reaction section.
Examples of devices for heating the outer wall of the reaction section include an electric heating device placed outside the outer wall, a heating device in which a heat medium is passed through the inside of a double-pipe outer wall, and an oil bath heating device in which the reaction section is immersed in a heating medium for heating.
The heat transfer medium passed through the inside of the double pipe is not limited as long as it can be heated to 200°C or higher, and steam, known heat transfer oil, known molten metal, known molten salt, etc. can be used.
The heat transfer oil, metal, and salt are preferably heated using an electric heater, and the temperature is preferably controlled within a range of ±0.2° C. Controlling the temperature within this range is preferred because thermal degradation proceeds uniformly.
An example of a device that directly heats the contents inside the reactor is a device that is inserted into the reactor and heats by passing the above-mentioned heat medium through a heating pipe.

The agitator for a tubular continuous reactor is not limited as long as it is capable of mixing the contents of the reaction section. It may be a mechanical agitator that rotates agitator blades using power from a drive unit, a static agitator that mixes the contents by passing them through gaps in baffles or other devices placed inside the reaction section, or a blow-in agitator that mixes the contents by blowing an inert gas, described below, into the material to be treated inside the reactor. Of these, static agitators (more preferably static mixers) and blow-in agitators are preferred because they allow thermal degradation to proceed uniformly and prevent deterioration of color.

The tubular continuous reactor used in the production method of the present invention can be any known device, with preferred examples including an extruder (a tubular continuous reactor equipped with a mechanical stirrer and an external wall heating device using a heater) and a reaction tube with a static mixer installed inside, and even more preferred is a double-tube reaction tube with a static mixer installed inside.

The tubular continuous reactor used in the production method of the present invention preferably has a reaction tube whose inner diameter changes continuously or discontinuously. A reaction tube whose inner diameter changes continuously or discontinuously may have multiple sections with different inner diameters as reaction sections, and it is preferable that reaction tubes with different inner diameters are arranged in series somewhere along the reaction path from the inlet to the outlet. Reaction tubes with different inner diameters may be connected so that the inner diameter changes gradually, so that the inner diameter changes continuously, or may be connected so that the inner diameter changes discontinuously.

When the reaction tube closest to the raw material inlet of the two reaction tubes is designated as the front tube and the reaction tube closest to the reactant outlet is designated as the final tube, the ratio (D1/De) of the inner diameter of the front tube (D1) to the inner diameter of the final tube (De) is preferably 0.2 to 0.8, more preferably 0.3 to 0.7. A ratio of D1/De within the preferred range is advantageous because it can prevent deterioration in the color and odor of the reaction product after thermal degradation.

The ratio (L1/D1) of the length (L1) of the front tube to D1 is preferably 150 to 1500, more preferably 200 to 1200. When L1/D1 is in this range, deterioration of the color and odor of the reaction product after thermal degradation can be suppressed, which is preferable.
The ratio (Le/De) of the final pipe length (Le) to De is preferably 200 to 800, more preferably 250 to 700. When Le/De is in this range, deterioration of the color and odor of the reaction product after thermal degradation can be suppressed, which is preferable.

The ratio of Ll/DI to Le/De [(Ll x De)/(Le x Dl)] is preferably 0.2 to 4.0, more preferably 0.5 to 1.0. When (Ll x De)/(Le x Dl) is in this range, deterioration of the color and odor of the reaction product after thermal degradation can be suppressed, which is preferable.
From the viewpoint of uniformity of thermal degradation, it is preferable that the two reaction tubes are connected via a connecting part whose inner diameter is gradually changed so that the inner diameter of the reactor does not change suddenly. There is no limitation on the length of the connecting part, but it is preferable that it is short.

In the production method of the present invention, the temperature at which the cycloolefin polymer is heated in the tubular continuous reactor in the thermal degradation step is 200 to 450° C., preferably 250 to 400° C. If the heating temperature of the cycloolefin polymer in the tubular continuous reactor is less than 200° C., the thermal degradation does not proceed, and if it exceeds 450° C., the color of the reaction product after thermal degradation deteriorates.
Here, heating the cycloolefin polymer to 200 to 450°C means that the temperature of the cycloolefin polymer in the tubular continuous reactor is 200 to 450°C.
The temperature of the cycloolefin polymer in the tubular continuous reactor can be confirmed by inserting a known thermometer or thermocouple into the reaction tube and directly measuring the temperature of the cycloolefin polymer in the tubular continuous reactor, and the temperature range can be controlled by controlling the heating device of the tubular continuous reactor while checking this temperature.

The heating temperature in the tubular continuous reactor in the thermal degradation step may be a constant temperature within the above temperature range (200 to 450°C), or may have portions heated at multiple different temperatures within the range of 200 to 450°C by using multiple heating devices that control the heating temperature.
When there are portions heated at different temperatures, from the viewpoint of uniformity of thermal degradation, it is preferable that the polymer comprises a portion where the cycloolefin polymer temperature is 200 to 300°C (more preferably 250 to 300°C) and a portion where the cycloolefin polymer temperature is 300 to 450°C (more preferably 370 to 420°C), and it is more preferable that the polymer is heated to 200 to 300°C and then to 300 to 450°C.

The residence time of the cycloolefin polymer in the tubular continuous reactor during the thermal degradation process is 0.5 to 10 hours (preferably 1 to 7 hours). If the reaction time is less than 0.5 hours, it is difficult to obtain a homogeneous product, and if it exceeds 10 hours, the resulting modified cycloolefin polymer will have a strong odor and a poor color.

The pressure inside the tubular continuous reactor in the thermal degradation step is preferably 0.1 to 200 kg/ ^cm² , more preferably 0.5 to 150 kg/ ^cm² . A pressure in this range is preferred because it can prevent deterioration in the color and odor of the reaction product after thermal degradation.

The thermal degradation step is preferably carried out under conditions where the oxygen concentration in the tubular continuous reactor is 15 to 500 ppm. When the oxygen concentration is within this range, deterioration of the color and odor of the reaction product after thermal degradation can be further suppressed, and the amount of terminal double bonds falls within a preferred range.
The oxygen concentration in the tubular continuous reactor can be adjusted by passing an inert gas or the like through the tubular continuous reactor while measuring the oxygen concentration in the reactor with an oxygen concentration meter before the start of thermal degradation and during thermal degradation.

The thermal degradation step can be carried out while passing an inert gas through it, if necessary. Examples of inert gases include argon, nitrogen, carbon dioxide, and water vapor. Nitrogen is preferred. When passing an inert gas through it, it is preferably passed through the tubular continuous reactor at a flow rate of 5 to 1,000 L/min.

In the thermal degradation step, the linear flow velocity of the cycloolefin polymer flowing through the tubular continuous reactor is preferably 0.5 to 100 m/hr, more preferably 1 to 80 m/hr. When the linear flow velocity is within this range, deterioration of the color and odor of the reaction product after thermal degradation can be suppressed, which is preferable.
Although it depends on the inner diameter and length of the tubular continuous reactor used, the weight per hour of the modified cycloolefin polymer obtained from the outlet in the thermal degradation step (i.e., the weight of the modified cycloolefin polymer discharged from the reactor per hour) is preferably 10 to 700 kg, more preferably 50 to 500 kg. This range is preferable because it not only can suppress deterioration in the color and odor of the reaction product after thermal degradation, but also can achieve good productivity.

In the production method of the present invention, the thermal degradation step may be carried out by mixing a catalyst with the cycloolefin polymer in order to promote the thermal degradation.
Examples of the catalyst include radical-generating catalysts [peroxide compounds (benzoyl peroxide, di-tert-butyl peroxide, dicumyl peroxide, etc.), azonitrile compounds {2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 4,4'-azobis(4-cyanovaleric acid)}, and cracking catalysts (silica-alumina, silica-magnesia, activated clay, etc.)].
When a catalyst is used, it is preferable to use 0.1 to 20 parts by weight, more preferably 1 to 10 parts by weight, of the catalyst relative to 100 parts by weight of the cycloolefin polymer. The catalyst may be added to the cycloolefin polymer before it is placed in the tubular continuous reactor, or may be added midway through the tubular continuous reactor.

In the production of the present invention, a thermal degradation step may be carried out with the addition of an antioxidant.
The phenolic antioxidant is preferably a hindered phenolic compound. Examples of the hindered phenolic compound include monocyclic hindered phenols [2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4-methylphenol, 6-tert-butyl-2,4-methylphenol, 2,6-di-tert-butylphenol, 2-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-ethylphenol, n-octadecyl-3-(4'-hydroxy-3,5-di-tert-butylphenyl)propionate, dioctadecyl benzo ... diethyl-4-hydroxy-3,5-di-tert-butylbenzylphosphonate, diethyl-4-hydroxy-3,5-di-tert-butylbenzylphosphonate, and 6-(4-oxy-3,5-di-tert-butyl-anilino)2,4-bis(n-octylthio)-1,3,5-triazine, etc.], bicyclic hindered phenols [4,4'-thiobis(6-tert-butyl-3-methylphenol), 4,4'-butylidenebis(6-tert-butyl-3-methylphenol), 4,4'- methylenebis(6-tert-butylphenol), 4,4'-bis(2,6-di-tert-butylphenol), 4,4'-thiobis(6-tert-butyl-o-cresol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-thiobis(6-tert-butyl-4-methylphenol), and 1,6-bis(3,5-di-tert-butyl-4-hydroxy-2-methylphenyl)butane, etc.], and polycyclic hindered phenols [1,1,3-tris(5- tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)mesitylene, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)mesitylene, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, and tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxymethyl]methane, etc.].

The phenolic antioxidant is preferably used in an amount of 0.2 parts by weight or less, more preferably 0.1 parts by weight or less, per 100 parts by weight of the cycloolefin polymer, and most preferably no antioxidant is used.
The antioxidant has the effect of preventing the coloration of the reaction product, but reducing the amount of antioxidant is preferred because it facilitates the progress of thermal degradation. In order to keep the number of double bonds within the preferred range by thermal degradation, it is most preferred not to use an antioxidant.
When an antioxidant is used, the antioxidant may be added to the cycloolefin polymer before it is placed in the tubular continuous reactor, or may be added midway through the tubular continuous reactor.

In the production method of the present invention, the raw material cycloolefin polymer may be directly charged into a tubular continuous reactor, where it is melted and heated to a predetermined temperature. However, it is preferable to include a melting step in which the cycloolefin polymer is melted before the thermal degradation step, and then charge the molten cycloolefin polymer into the tubular continuous reactor.

The melting process for melting the cycloolefin polymer can be carried out by heating the cycloolefin polymer to above its melting point using a known reaction vessel equipped with a stirrer and a heater.

The production method of the present invention preferably includes a de-oligomerization step after the thermal degradation step.
The de-oligomerization step is a step of removing volatile components produced as by-products by thermal degradation, and can be carried out by subjecting the thermally degraded reaction product to conditions of a pressure of 0.013 to 1.3 kPa and a temperature of 300 to 450°C and distilling off the volatile components. The de-oligomerization step may be carried out in a known evacuable closed reaction vessel equipped with a stirrer and a heater, in which the reaction product discharged from the tubular continuous reactor is de-oligomerized. Alternatively, the de-oligomerization step may be carried out by connecting a tubular continuous reactor for carrying out the de-oligomerization step to a tubular continuous reactor for carrying out the thermal degradation step and evacuating the inside of the vessel to the aforementioned reduced pressure.

The de-oligomerization step is preferably carried out until the content of components having a number average molecular weight of 1,000 or less is 10% by weight or less, based on the weight of the treated material containing the modified cycloolefin polymer, and more preferably until it is 1% by weight or less. This range is preferred as it results in good mechanical strength for the modified cycloolefin polymer.

The weight of components with a number average molecular weight of 1,000 or less contained in the product treated in the de-oligomerization step can be calculated by measuring with GPC. From the standpoint of the hue of the reaction product, the de-oligomerization step is preferably carried out for 0.1 to 20 hours, and more preferably for 1 to 10 hours.

The modified cycloolefin polymer obtained by the production method of the present invention can be molded into powder or pellets using known methods.

The modified cycloolefin polymer obtained by the production method of the present invention preferably has a number average molecular weight of 1,000 to 100,000.

The Gardner number measured in accordance with JIS K0071-2 is preferably 8 or less.

The double bonds in the modified cycloolefin polymer obtained by the production method of the present invention are reactive and can be used favorably to modify various polymers and as raw materials for producing functional polymers.

The present invention will be further explained below with reference to examples, but the present invention is not limited thereto. In the following, Examples 1, 2, and 6 correspond to Reference Examples 1, 2, and 3, respectively.

Example 1
A continuous tubular reactor was used, in which a front tube (inner diameter: 49.5 mm, length: 10 m) equipped with a static mixer inside and a rear tube (inner diameter: 97.1 mm, length: 50 m) equipped with a static mixer inside were connected in series. The front tube and the rear tube were immersed in temperature-controlled salt baths at 250±1°C and 390±1°C, respectively, and heated. While introducing nitrogen into the reactor at a flow rate of 0.5 L/min, pellets of a cycloolefin polymer (manufactured by Zeon Corporation, trade name "ZEONOR1060R", hydrogenated tricyclo[4.3.0.1 ^2,5 ]-3-decene polymer, density (ASTM D792): 1.01 g/cm ³ , glass transition temperature (JIS K-7121): 100°C, number average molecular weight: 105,000) were continuously charged from the inlet, and a thermal degradation step was carried out while adjusting the charging rate of the cycloolefin polymer so that the residence time in the tubular continuous reactor was 2.7 hours. The temperature of the cycloolefin polymer in the front tube during the thermal degradation step, measured with a thermometer installed in the reactor, was 250°C, the temperature of the cycloolefin polymer in the rear tube was 390°C, and the oxygen concentration in the reactor, measured with an oxygen concentration meter, was 500 ppm.
The thermal degradation process was continued for 5 hours after the thermal degradation product was discharged from the outlet of the tubular continuous reactor. The analysis of the thermal degradation product (after 4 hours) was conducted by taking an analytical sample, not just after the start of the discharge of the thermal degradation product and just before the end of the discharge, and found to have a double bond count of 3.1 per 1,000 carbon atoms, a number average molecular weight of 11,000, and a Gardner color index of 4.

Example 2
The same tubular continuous reactor as in Example 1 was used, and both the front tube and the rear tube were immersed in a salt bath at 200±1°C and heated so that the residence time in the tubular continuous reactor was 10 hours, and the flow rate of nitrogen into the reactor was 10 L/min. Except for this, the cycloolefin polymer was continuously fed into the tubular continuous reactor under the same conditions as in Example 1 to carry out thermal degradation.
The temperature of the cycloolefin polymer in the front pipe during the thermal degradation process, measured by a thermometer installed in the reactor, was 200°C, the temperature of the cycloolefin polymer in the rear pipe was 200°C, and the oxygen concentration in the reactor, measured by an oxygen concentration meter, was 50 ppm.
The thermal degradation process was carried out for 5 hours after the thermal degradation product was discharged from the outlet of the tubular continuous reactor. An analytical sample (thermal degradation product after 4 hours) was collected at a time other than immediately after the start and end of the discharge of the thermal degradation product. The number of double bonds per 1,000 carbon atoms was 0.01, the number average molecular weight was 100,000, and the Gardner color index was 1.

Example 3
The same tubular continuous reactor as in Example 1 was used, and thermal degradation was carried out by continuously feeding a cycloolefin polymer into the tubular continuous reactor under the same conditions as in Example 1, except that both the front tube and the rear tube were immersed in a salt bath at 450±1°C and heated so that the residence time in the tubular continuous reactor was 0.5 hours, and the flow rate of nitrogen into the reactor was 20 L/min.
The temperature of the cycloolefin polymer in the front pipe during the thermal degradation process, measured by a thermometer installed in the reactor, was 450°C, the temperature of the cycloolefin polymer in the rear pipe was 450°C, and the oxygen concentration in the reactor, measured by an oxygen concentration meter, was 50 ppm.
The thermal degradation process was carried out for two hours after the thermal degradation product was discharged from the outlet of the tubular continuous reactor. An analytical sample (thermal degradation product after one hour) was collected at a time other than immediately after the start of discharge of the thermal degradation product and immediately before the end of discharge. The sample had 15 double bonds per 1,000 carbon atoms, a number average molecular weight of 2,000, and a Gardner color index of 8.

Example 4
The same tubular continuous reactor as in Example 1 was used, and thermal degradation was carried out by continuously feeding a cycloolefin polymer into the tubular continuous reactor under the same conditions as in Example ¹ , except that a cycloolefin polymer (manufactured by Zeon Corporation, trade name "ZEONOR1020R", a hydrogenated tricyclo[ ^4.3.0.12,5 ]-3-decene polymer, density (ASTM D792): 1.01 g/cm3, glass transition temperature (JIS K-7121): 102°C, number average molecular weight: 33,000) was used.
The temperature of the cycloolefin polymer in the front pipe during the thermal degradation process, measured by a thermometer installed in the reactor, was 250°C, the temperature of the cycloolefin polymer in the rear pipe was 390°C, and the oxygen concentration in the reactor, measured by an oxygen concentration meter, was 500 ppm.
The thermal degradation process was continued for 5 hours after the thermal degradation product was discharged from the outlet of the tubular continuous reactor. The analysis of the thermal degradation product after 4 hours (taken at two times, not just after the start and end of the discharge of the thermal degradation product) revealed that the number of double bonds per 1,000 carbon atoms was 3.4, the number average molecular weight was 4,000, and the Gardner color index was 4.

Example 5
The same tubular continuous reactor as in Example 1 was used, and thermal degradation was carried out by continuously feeding a cycloolefin polymer into the tubular continuous reactor under the same conditions as in Example ¹ , except that a cycloolefin polymer (manufactured by Zeon Corporation, trade name "ZEONOR480R", a hydrogenated product of 8-ethyl-tetracyclo[ ^{4.4.0.12,5.17,10} ]-3-dodecene polymer, density (ASTM D792): 1.01 g/cm3, glass transition temperature (JIS K-7121): 138°C, number average molecular weight: 30,000) was used.
The temperature of the cycloolefin polymer in the front pipe during the thermal degradation process, measured by a thermometer installed in the reactor, was 250°C, the temperature of the cycloolefin polymer in the rear pipe was 390°C, and the oxygen concentration in the reactor, measured by an oxygen concentration meter, was 500 ppm.
The thermal degradation process was continued for 5 hours after the thermal degradation product was discharged from the outlet of the tubular continuous reactor. The analysis of the thermal degradation product (after 4 hours) was conducted by taking an analytical sample, not just after the start of the discharge of the thermal degradation product and just before the end of the discharge, and found to have a double bond count of 3.3 per 1,000 carbon atoms, a number average molecular weight of 3,800, and a Gardner color index of 4.

Example 6
The thermal degradation product obtained in Example 1 was used as it was as a resin modifier and mixed with a cycloolefin polymer under the following conditions.
First, 90 parts of the cycloolefin polymer used in Example 1 (manufactured by Zeon Corporation, trade name "ZEONOR1060R") and the thermal degradation product obtained in Example 1 were kneaded in a twin-screw extruder at 280°C for a residence time of 30 seconds, and then pelletized.
The obtained pellets were used to prepare molded pieces of 100 x 100 x ^{2 mm} using an injection molding machine (product name "PS40E5ASE", Nissei Plastic Industrial Co., Ltd.) under conditions of a cylinder temperature of 280°C, an injection pressure of 800 kg/cm2, an injection speed of 200 mm/s, and a mold temperature of 80°C. The smoothness of the molded piece surface was evaluated by measuring the surface roughness using a Keyence "Digital Microscope VHX-600."
The surface roughness of the obtained test piece was measured and found to be 0.65 μm.
When only the cycloolefin polymer used in Example 1 (manufactured by Zeon Corporation, trade name "ZEONOR1060R") was injection molded under the same conditions, the surface roughness was 1.3 μm.

<Comparative Example 1>
5 g of pellets of cycloolefin polymer (manufactured by Zeon Corporation, trade name "ZEONOR1060R", density (ASTM D792): 1.01 g/cm ³ , glass transition temperature (JIS K-7121): 100°C) were charged into a batch reactor of a heat-resistant glass pyrolysis apparatus similar to that described in Journal of Polymer Science: Polymer Chemistry Edition, 21, 703 (1983), and after replacing the atmosphere in the system with nitrogen, the internal pressure was reduced to 0.27 kPa and the system was heated to 200°C to melt the cycloolefin polymer. Thereafter, the reactor was submerged in a metal bath set to 390°C and heated.
While the inside of the reactor was kept under reduced pressure of about 2 mmHg, the molten cycloolefin polymer was heated for 8 hours while bubbling nitrogen gas into it.
The reactor was then cooled to room temperature, the pressure in the system was returned to normal, and the contents were dissolved in hot xylene and removed. The resulting hot xylene solution was added dropwise to methanol to obtain a precipitate, which was then recovered to obtain a comparative modified cycloolefin polymer. The comparative modified cycloolefin polymer had a double bond count of 1.9 per 1,000 carbon atoms, a number average molecular weight of 11,000, and a Gardner color score of 14.

The modified cycloolefin polymers of the Examples obtained by the production method of the present invention were less colored than the modified cycloolefin polymer obtained by the production method of Comparative Example 1, which did not use a tubular continuous reactor.
Furthermore, in Example 6, the resin composition using the thermally degraded product of the present invention had small surface roughness of the molded piece, which shows that the resin modifier using the thermally degraded product of the present invention functions as an excellent agent for imparting surface smoothness to cycloolefin polymers.

The modified cycloolefin polymer obtained by the modified cycloolefin polymer production method of the present invention has little coloration and can be preferably used as a resin modifier, etc.

Claims (3)

The method for producing a modified cycloolefin polymer has a carbon-carbon double bond and a number average molecular weight of 1,000 to 4,000 , and includes a thermal degradation step of heating the cycloolefin polymer in a tubular continuous reactor so that the temperature of the cycloolefin polymer inside is 200 to 450°C, and the residence time of the cycloolefin polymer in the tubular continuous reactor in the thermal degradation step is 0.5 to 10 hours. The method for producing a modified cycloolefin polymer according to claim 1, wherein the tubular continuous reactor used in the thermal degradation step has a reaction tube whose inner diameter changes continuously or discontinuously. The method for producing a modified cycloolefin polymer according to claim 1 or 2, wherein the tubular continuous reactor includes a portion where the internal cycloolefin polymer temperature is 200 to 300°C and a portion where the internal cycloolefin polymer temperature is 300 to 450°C.