KR20150031961A - Nitrile rubber and method of preparing them - Google Patents

Abstract

The present invention relates to a nitrile rubber and a manufacturing method thereof and, more specifically, a nitrile rubber, which makes less molecules and contribution to an outstanding polymerization speed and vulcanization speed; has an advantageous property for workability in a process of vulcanization; and manufactures rubber composition having uniform molecular weight due to low molecular weight distribution, thereby having an outstanding roll processing and injection molding processing and thus improving properties of completed products, and a manufacturing method thereof.

Description

NITRILE RUBBER AND METHOD OF PREPARING THEM [0002]

More particularly, the present invention relates to a nitrile rubber and a process for producing the same. More specifically, the present invention relates to a nitrile rubber and a process for producing the same. More specifically, the present invention relates to a nitrile rubber, The present invention relates to a nitrile rubber excellent in roll processing and injection molding processing and capable of improving the physical properties of a final product and a production method thereof.

In general, the nitrile rubber is a copolymer of acrylonitrile and butadiene, and the amount of acrylonitrile bound is between 15 and 50%, which is randomly copolymerized at various ratios.

The greatest advantage of the nitrile rubber is that it has excellent oil resistance because the nitrile group in the acrylonitrile has polarity, and its characteristics are greatly different depending on the amount of bound nitrile. The oil resistance is determined by the amount of bonded nitrile, swelling, and the aniline point of oil (the lowest temperature at which the hydrocarbon completely dissolves in the same volume of aniline, which can be measured to determine the composition of the light mineral oil such as gasoline) In the relationship, the higher the amount of bound nitrile, the better the oil resistance, and the higher the aniline point, the smaller the swelling.

The oil referred to here is a mineral oil, that is, a petroleum hydrocarbon structure, which is generally used as a lubricating oil or a hydraulic fluid. Particularly, since various additives may be added to these oils and their effects may be exerted, it is preferable to evaluate the oil resistance of the rubber at the aniline point and measure the change or swelling of the physical properties of the oil used as the seal product Do.

Further, as a result of measuring the compression set of the O-ring in the oil at a high temperature for a long period of time, it is known that the O-ring has very excellent properties and at the same time, the volume change rate shows a good swelling property. Good things are presumed.

Nitrile rubber is most suitable as O-ring, V-packing and oil seal for lubricating oil, hydraulic oil and fuel oil in all fields such as industrial machinery, construction machinery, . The usable temperature of the nitrile rubber varies greatly depending on the compounding. However, it is used at a temperature of -50 to -120 ° C, particularly at a low temperature for a low nitrile content in a device for an electrode, a cold place, etc. In addition, the relatively high nitrile content is not only good in heat resistance and mechanical properties, but also excellent in gas permeability, and can be used for vacuum up to about 10 torr.

The polymerization takes place through conventional low-temperature emulsion polymerization, which is treated in the form of a bale through the solidification process using an aggregating agent. However, it is necessary to solve the problem that the productivity is deteriorated in order to periodically remove the foreign material from the mold due to the residual foreign matter during the production of the nitrile rubber.

It is an object of the present invention to solve the above problems of the prior art and to provide a nitrile rubber having an alkyl dithiol end group having a low molecular weight and contributing to excellent polymerization rate and vulcanization rate and having characteristics favorable for workability upon vulcanization, And a manufacturing method thereof.

In addition, since the rubber composition having a more uniform molecular weight can be produced due to a low molecular weight distribution, the present invention is excellent in roll forming and injection molding, and accordingly, an alkyl dithiol end group capable of improving the physical properties of the final product And a process for producing the same.

In order to achieve the above object, the present invention provides a nitrile rubber having an alkyl dithiol end group.

In addition,

In the preparation of nitrile rubbers having alkyl dithiol end groups,

The nitrile rubber having an alkyl dithiol end group is obtained by reacting at least one vinyl cyanide compound and at least one conjugated diene compound with a sulfur-containing emulsifier, a fat-soluble initiator and an emulsion polymerization under an alkyl dithiol Of the present invention.

In addition,

A nitrile rubber having an alkyl dithiol end group as described above, and at least one crosslinking agent.

Further,

A nitrile rubber having an alkyl dithiol end group as described above, or a process for producing a molded rubber product by vulcanizing a vulcanizable mixture in a molding process.

Hereinafter, the present invention will be described in detail.

Specifically, the present invention provides a nitrile rubber having an alkyl dithiol end group.

The alkyl dithiol end group may be a terminal group of a dithiol having an alkyl group having 8 to 18 carbon atoms.

The alkyl dithiol terminal group may be, for example, in the range of 0.05 to 3 parts by weight based on 100 parts by weight of the total amount of the compound constituting the nitrile rubber.

The nitrile rubber may have a molecular weight distribution (PDI) in the range of 3 to 4, for example.

The nitrile rubber may include, for example, 15 to 50% by weight of at least one vinyl cyanide compound and 85 to 50% by weight of at least one conjugated diene compound.

As a specific example, the nitrile rubber may comprise 20 to 40% by weight of at least one vinyl cyanide compound and 80 to 60% by weight of at least one conjugated diene compound.

The at least one vinyl cyanide compound may be at least one selected from among acrylonitrile, methacrylonitrile, fumaronitrile,? -Chloronitrile and? -Cyanoethyl acrylonitrile.

The conjugated diene compound may be one or more selected from among 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene and isoprene have.

The process for producing the nitrile rubber having an alkyl dithiol end group according to the present invention can be carried out, for example, by a method in which one or more vinyl cyanide compounds and at least one conjugated diene compound are reacted with sulfur-containing emulsifiers, oil-soluble initiators and alkyl dithiol by emulsion polymerization It may be manufactured.

The sulfur-containing emulsifier may be, for example, selected from the group consisting of alkylaryl sulfonates, alkali metal alkyl sulfates, sulfonated alkyl esters such as alkyldiphenyl oxide disulfonic acid, alkali salts of rosin acid, and naphthalenesulfonic acids such as naphthalenesulfonic acid. Or more.

The sulfur-containing emulsifier may be, for example, 0.5 to 3 parts by weight, 0.5 to 2 parts by weight, or 1 to 1.5 parts by weight based on 100 parts by weight of the total amount of the compound constituting the nitrile rubber.

The oil-soluble initiator may be at least one member selected from the group consisting of p-menthol hydroperoxide, benzoyl peroxide, hydrogen peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, decanoyl peroxide, Butyl hydroperoxide, t-butyl hydroperoxide, acetylacetone peroxide, dicetyl peroxydicarbonate, t-butyl peroxyacetate, t-butyl peroxymaleic acid, t-butyl 2-t-butyl azo-2-cyanopropane, dimethylazodiisobutyrate, azodiisobutyronitrile, 2-t-butyl azo-1-cyano (Tert-butylperoxy) butyrate, ethyl 3,3-bis (t-butylperoxy) butyrate, 1,1-t-amyl azo-1-cyanocyclohexane, 2,2- - di- (t-butylperoxy) cyclohexane, punanhydroperoxa De, and 2,5-dimethyl-2,5-bis (t- butylperoxy) hexane . ≪ / RTI >

The fat-soluble initiator may be, for example, 0.001 to 0.5 parts by weight, 0.001 to 0.1 parts by weight, or 0.01 to 0.1 parts by weight based on 100 parts by weight of the total amount of the compounds constituting the nitrile rubber.

The alkyl dithiol may be at least one selected from 1,12-dodecanedithiol and 1,8-octanedithiol.

The alkyldithiol may be, for example, 0.01 to 5 parts by weight, 0.01 to 3 parts by weight, or 0.1 to 1 part by weight based on 100 parts by weight of the total amount of the compound constituting the nitrile rubber.

The emulsion polymerization may be carried out at a polymerization temperature of, for example, 5 to 25 ° C, or 10 to 25 ° C for 7 to 8 hours, or 7.5 to 7.9 hours, until the polymerization conversion rate reaches 80%.

The nitrile rubbers having an alkyl dithiol end group produced by the emulsion polymerization can be solidified, washed and dried according to a conventional post-treatment procedure after completion of the polymerization at a polymerization conversion of 80%.

For example, the solidification may be one or more sodium or potassium salts used to solidify at 50-100 DEG C and 5% or less by weight of calcium chloride, based on the total amount of salt used for solidification during solidification.

As a specific example, the sodium or potassium salt may be at least one halide of sodium or potassium, at least one nitrate or at least one sulfate.

In another example, the coagulation uses a mixture of two or more salts, wherein the salt is a different salt of the same monovalent metal or a variety of different monovalent metal salts

During or before solidification, one or more aging inhibitors may be added, and the washing may be carried out at 50 to 90 < 0 > C.

The drying may be performed using a roll dryer, a hot-air drier or the like.

The dried nitrile rubber may be 0.4% or less, 0.1% or less, or 0.01 to 0.1% of the amount of contamination (hereinafter referred to as "mold contamination amount") on the surface of the mold after pressing at 130 ° C. for 300 seconds.

The solidified product may have a percentage (%) of 0.05% or less, 0.01% or less, or 0.005% to 0.01% of the product weight divided by the weight of the total compound administered.

In the above production method, the PDI may be 3 to 4 or less.

Also, a vulcanizable mixture characterized by containing the above-mentioned nitrile rubber having an alkyl dithiol end group and at least one crosslinking agent can be provided.

The mixture may comprise one or more additives selected from fillers, fillers, activators, ozone blocking agents, aging inhibitors, antioxidants, processing aids, extender oils, plasticizers, reinforcing materials and release agents.

Further, it is possible to provide a method for producing a rubber-based molded article in which the above-mentioned nitrile rubber or vulcanizable mixture is vulcanized in a molding process.

Wherein the molded article has a tensile strength in the range of 225 to 246 kgf / cm2, an elongation in the range of 377 to 387%, and a 300% modulus in the range of 174 to 185, wherein the tensile strength, elongation, 504 < / RTI >

The shaped body may be, for example, a seal, a cap, a hose or diaphragm, an O-ring seal, a flat seal, a pleated seal ring, a seal sleeve, a seal cap, a dust seal cap, a plug seal, an insulation hose, (servo) control hose or pump diaphragm.

According to the present invention, it is possible to provide a nitrile rubber having an alkyl dithiol end group having low molecular weight production, contributing to an excellent polymerization rate and vulcanization rate, and having characteristics favorable to workability. In addition, since the rubber composition having a lower molecular weight distribution and a more uniform molecular weight can be produced, the roll processing and injection molding processing are excellent, and thus the physical properties of the final product can be improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Changes and modifications may fall within the scope of the appended claims.

Example  One

To 100 parts by weight of a monomer composed of 65 parts by weight of 1,3-butadiene and 35 parts by weight of acrylonitrile was added 1.5 parts by weight of alkyl diphenyl oxide disulfonic acid (product name: Dowfax 2a1), 0.05 part by weight of p-menthanhydroperoxide , 0.5 part by weight of 1,12-dodecanedithiol, and 200 parts by weight of water were added, and the emulsion polymerization was carried out at 10 캜, and the conversion was completed at the time of 80% conversion. The reaction time is summarized in Table 2 below. After the solidification process, the coagulated material was obtained, washed, and dried using a roll dryer to prepare a rubber.

Example  2, Comparative Example  1-6

As shown in the following Table 1 in Example 1, except that the kind and content of alkyl diphenyl oxide disulfonic acid (product name: Dowfax 2a1) and 1,12-dodecanedithiol were changed, Was repeated to prepare a rubber.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example
5 Dowfax 2a1 2.5 1.25 2.5 2.5 Fatty acid 2.5 Potassium oleate 2.5 Potassium rosinate 2.5 1,12-dodecanedithiol 0.5 0.2 0.5 t-Dodecyl mercaptan 0.5 0.5 0.5 2,2,4,6,6-pentamethylheptane-4-thiol) 0.5

[Test Example]

The properties of the rubbers obtained in the above Examples and Comparative Examples were evaluated as follows, and the results are shown in Table 2.

* Method for measuring molecular weight : The solidified product was stirred in DMF at 0.1 wt% for 24 hours, and then the weight average molecular weight (Mw) and the molecular weight distribution (Polydispersity Index, PDI = Mw / Mn) were measured by GPC.

* Method for Measuring Mold Pollution : The mold contamination was measured by putting a certain amount of nitrile rubber which had undergone the drying process after solidification on a mold plate using a press, pressing it at 130 ° C. for 300 seconds, removing the nitrile rubber from the mold plate After that, the amount of contaminants on the surface of the mold was measured.

* Method of determination of the formed coagulum : The resultant coagulum is expressed as a percentage (%) divided by the weight (g) of the formed coagulum in the reaction vessel divided by the weight (g) of the total compound administered.

division Example
One Example
2 Comparative Example
One Comparative Example
2 Comparative Example
3 Comparative Example 4 Comparative Example 5 BD-Dimer (ppm) 0.053 0.036 0.875 0.950 1.135 0.138 0.065 PDI 3.7 3.5 4.5 4.6 5.0 4.8 4.3 Polymerization time (hr) 7.9 7.5 7.5 8 9 8.2 7.9 Mold Contamination (%) 0.1 0.01 1.2 2.1 4.5 0.5 0.3 Generated coagulate (%) 0.01 0.005 0.1 0.3 0.5 0.02 0.01

As shown in Table 2, in Example 1-2 according to the present invention, the BD-Dimer content (ppm), the PDI value, the polymerization time, the mold contamination amount, and the resultant coagulated product were improved compared with Comparative Example 1-5 .

Further, the physical property measurements of Examples 1-2 and Comparative Examples 1-5 measured according to the following physical property measuring methods are summarized in Table 3 below.

≪ Measurement of physical properties of polymer &

* MV (Mooney viscosity): The Mooney viscosity of the raw polymer was measured according to DIN 53523/3 or ASTM D 1646.

* MSR (Mooney stress-relaxation rate): Measured at 100 ° C using a shear disk viscometer according to ISO 289-4: 2003E. Note that the higher the MSR value, the lower the long chain branch fraction.

* [Delta] ACN: Determination of the glass transition temperature and so-called starting and end points thereof are determined using DSC according to ASTM E 1356-03 or DIN 11357-2. Based on the measured start and end points, the Gordon-Taylor relationship can be applied to calculate the ACN content for the start and end points, and the difference between the ACN distributions can be determined from these values.

Tg = 1.4564 * [ACN] -77.147, ACN = ACN end point - ACN start point

<Vulcanization characteristics (MDR: Moving DieRheometer)>

The vulcanized profile and its associated analytical data were measured in a Monsanto MDR2000 rheometer according to ASTM D5289-95.

* T5: The time required to reach 5% vulcanization was measured (160 DEG C, 3 minutes).

* V _max (vulcanization rate): means the maximum torque required for 100% vulcanization.

<Mechanical Properties>

The mechanical properties of the rubber were measured on the vulcanizate according to DIN 53 504. Using a Banbury mixer according to ASTM D3187.

Tensile strength (TS: kgf / cm ² ): The above compound was cured at 145 占 폚 for 45 minutes, and the tensile strength of the 300% vulcanized product was measured.

Elongation (%): The mixture was cured at 145 占 폚 for 45 minutes, and elongation of the vulcanizate was measured.

* 300% modulus: The blend was cured at 145 占 폚 for 45 minutes, and the modulus at 300% elongation was measured.

division Example Comparative Example One 2 One 2 3 4 5 Polymer properties MV 50 51 50 51 49 50 50 MSR 0.351 0.389 0.298 0.271 0.291 0.301 0.311 Vulcanization characteristic T5 (min) 2.0 2.3 2.7 2.9 4.0 2.5 2.4 V _max (kgf.cm) 62.5 65.0 55.0 54.0 50.0 56.1 60.0 Mechanical properties TS (kgf / cm ² ) 230 240 210 205 190 204 220 Elongation (%) 380 394 394 401 386 374 405 300% modulus 174 181 150 145 135 155 167

As shown in Table 3, it was confirmed that in Example 1-2 according to the present invention, improved curability and improved mechanical properties were obtained under the same or similar polymer properties as in Comparative Example 1-5.

Claims (20)

Nitrile rubber having an alkyl dithiol end group.
The method according to claim 1,
Wherein the alkyl dithiol end group is a terminal group of a dithiol having an alkyl group having 8 to 18 carbon atoms.
The method according to claim 1,
Wherein the alkyl dithiol terminal group is in the range of 0.05 to 3 parts by weight based on 100 parts by weight of the total amount of the compound constituting the nitrile rubber.
The method according to claim 1,
Wherein said nitrile rubber is in the range of PDI 3-4.
The method according to claim 1,
Wherein said nitrile rubber comprises 15 to 50 wt% of at least one vinyl cyanide compound and 85 to 50 wt% of at least one conjugated diene compound.
In the preparation of nitrile rubbers having alkyl dithiol end groups,
The nitrile rubber having an alkyl dithiol end group is obtained by reacting at least one vinyl cyanide compound and at least one conjugated diene compound with a sulfur-containing emulsifier, a fat-soluble initiator and an emulsion polymerization under an alkyl dithiol &Lt; / RTI &gt;
The method according to claim 6,
Wherein the sulfur-containing emulsifier is at least one selected from alkylaryl sulfonates, alkali metal alkyl sulfates, sulfonated alkyl esters, alkali salts of rosin acid, and naphthalenesulfonic acids.
The method according to claim 6,
Wherein the sulfur-containing emulsifier is in the range of 0.5 to 3 parts by weight based on 100 parts by weight of the total of the compounds constituting the nitrile rubber.
The method according to claim 6,
The fat-soluble initiator may be selected from the group consisting of p-menthol hydroperoxide, benzoyl peroxide, hydrogen peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, decanoyl peroxide, lauryl peroxide, Hydroperoxide, p-menthol hydroperoxide, t-butyl hydroperoxide, acetylacetone peroxide, dicetyl peroxydicarbonate, t-butyl peroxyacetate, t-butyl peroxymaleic acid, t- 2-t-butyl azo-2-cyanopropane, dimethyl azodiisobutyrate, azodiisobutyronitrile, 2-t-butyl azo-1-cyanocyclohexane, 1-t-amyl azo-1-cyanocyclohexane, 2,2-bis- (t-butylperoxy) butane, ethyl 3,3-bis (t-butylperoxy) butyrate, (t-butylperoxy) cyclohexane, phenanhydroperoxide and 2 , 5-dimethyl-2,5-bis (t-butylperoxy) hexane Wherein the nitrile rubber is at least one selected from the group consisting of ethylene and propylene.
The method according to claim 6,
Wherein the fat-soluble initiator is present in an amount of 0.001 to 0.5 parts by weight based on 100 parts by weight of the total of the compounds constituting the nitrile rubber.
The method according to claim 6,
Wherein the alkyl dithiol is at least one selected from the group consisting of 1,12-dodecanedithiol, and 1,8-octanedithiol.
The method according to claim 6,
Wherein the alkyl dithiol is present in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the total of the compounds constituting the nitrile rubber.
The method according to claim 6,
Wherein the emulsion polymerization is carried out at a polymerization temperature of 5 to 25 占 폚 for a time required for the polymerization conversion to reach 80% to be 7 to 8 hours.
The method according to claim 6,
Wherein the nitrile rubber having an alkyl dithiol end group produced by the above emulsion polymerization is subjected to polymerization at a polymerization conversion rate of 80%, followed by coagulation, washing and drying.
15. The method of claim 14,
Wherein the dried nitrile rubber has a contamination amount of 0.4% or less on the surface of the mold after being compressed at 130 캜 for 300 seconds.
15. The method of claim 14,
Wherein the solidified product has a percentage (%) of the produced weight divided by the weight of the total compound administered in an amount of 0.05% or less.
The method according to claim 6,
Wherein the production method is PDI 3-4 or less.
A nitrile rubber having an alkyl dithiol end group according to claim 1, and at least one crosslinking agent.
A nitrile rubber having an alkyl dithiol end group according to claim 1, or a vulcanizable mixture according to claim 18, is vulcanized in a molding process.
20. The method of claim 19,
The moldings may be in the form of a seal, a cap, a hose or diaphragm, an O-ring seal, a flat seal, a pleated seal ring, a seal sleeve, a seal cap, ) Control hose or pump diaphragm.