JP2006328280A - Method for modifying polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To introduce organic functional groups into a polymer at relatively low temperatures and by a simple operation without using any organic solvent. <P>SOLUTION: A method for modifying the polymer is provided, comprising the following process: The polymer that is soluble or swelling in carbon dioxide in a supercritical condition is made to coexist in a supercritical carbon dioxide with a radical initiator and a compound having in the molecule a nitroxide radical as a radical stable at room temperature to introduce organic groups derived from the nitroxide radical into the polymer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for modifying a polymer, and more particularly to a method for modifying a polymer in which a group derived from a nitroxide radical is introduced into a polymer at a relatively low temperature without using an organic solvent.

  Various methods for modifying polymers that introduce functional groups according to the purpose into polymers such as cross-linkable rubbers and thermoplastic polymers are known. On the other hand, as a radical stable at room temperature, for example, Patent Document 1 describes a method of synthesizing a block polymer using a nitroxide radical, and Patent Document 2 uses a polyfunctional nitroxide radical as a reversible crosslinking agent. The use is described. Furthermore, Patent Document 3 describes that a functional group is introduced into a polymer using X-TEMPO (tetramethylpiperidinyloxy radical) and a radical initiator.

U.S. Pat. No. 4,581,429 Special table 2003-524037 gazette JP 2004-182926 A

  As described above, it is known to introduce and modify various functional groups into various polymers using, for example, a compound having a nitroxide radical that is stable at room temperature in the molecule. Conventionally, it is generally modified with a solvent, particularly an organic solvent. However, there are polymers that do not dissolve in an organic solvent or have a relatively high melting point and are difficult to modify in an organic solvent. Is in a state that must be modified by a solid mixing reaction.

  Accordingly, an object of the present invention is to introduce an organic group derived from a compound having a nitroxide radical that is stable at room temperature into a polymer at a relatively low temperature and with a simple operation without using an organic solvent. It is to provide a method for modifying a polymer.

  According to the present invention, in supercritical carbon dioxide, a polymer that dissolves or swells in carbon dioxide in a supercritical state coexists with a compound having a radical initiator and a nitroxide radical that is a stable radical at room temperature in the molecule. There is provided a method for modifying a polymer, wherein an organic group derived from the nitroxide radical is introduced into the polymer.

  According to the present invention, since the modification of the polymer is performed in supercritical carbon dioxide, the reaction temperature (particularly high temperature) is less restricted than the reaction in a normal organic solvent, and the modified polymer after modification. And the solvent are easily separated. On the other hand, compared with the method of modifying by solid reaction, there is no problem that special equipment such as a closed mixer is required, and even a high melting point polymer can be modified at a temperature below the melting point. it can. Furthermore, since the polymer does not receive a high temperature history, there is no possibility that the physical properties inherent to the polymer are impaired.

  As a result of researches to solve the above-mentioned problems, the inventors of the present invention have developed nitroxide radicals that are stable at room temperature such as radical-degradable or crosslinkable polymers, organic peroxides, and TEMPO derivatives in supercritical carbon dioxide. It has been found that an organic group or a functional group derived from a compound having a nitroxide radical in the molecule can be introduced into the molecule by allowing the compound to be present in the molecule.

  The polymer that can be modified by the modification method of the present invention is not particularly limited, and can include any polymer that can be radicalized with an organic peroxide and can be dissolved or swelled in supercritical carbon dioxide, and particularly has a melting point. Suitable for modifying polymers that are high and difficult to modify in conventional organic solvents.

  Examples of polymers that are conveniently modified by the modification method of the present invention include various butyl rubbers, various halogenated butyl rubbers, copolymerized rubbers of isomonoolefin and paramethylstyrene and their halides, various butadiene rubbers, various styrene butadiene rubbers, Various isoprene rubbers, various natural rubbers, various nitrile rubbers, hydrogenated products thereof, various ethylene propylene copolymers, various ethylene propylene diene terpolymer rubbers and other crosslinkable rubbers and ethylene butene copolymers, Examples thereof include polystyrene-based TPE (SEBS, SEPS), polyolefin-based TPE, polymers containing propylene units such as polypropylene and polypropylene copolymers, and thermoplastic polymers such as fluororubber. These polymers are merely examples, and it goes without saying that the polymers that can be modified by the method of the present invention are not limited thereto.

  The organic peroxide that can be used in the modification method of the present invention is not particularly limited as long as it can radicalize the polymer to be modified. For example, benzoyl peroxide (BPO), t-butylperoxybenzoate (Z), Dicumyl peroxide (DCP), t-butylcumyl peroxide (C), di-t-butyl peroxide (D), 2,5-dimethyl-2,5-di-t-butylperoxyhexane (2, 5B), 2,5-dimethyl-2,5-di-t-butylperoxy-3-hexyne (Hexyne-3), 2,4-dichloro-benzoyl peroxide (DC-BPO), di-t-butyl Peroxy-di-isopropylbenzene (P), 1,1-bis (t-butylperoxy) -3,3,5-trimethyl-cyclohexane (3M) Organic peroxides such as n-butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, and azodicarbonamide (ADCA), azobisiso Butyronitrile (AIBN), 2,2'-azobis- (2-amidinopropane) dihydrochloride, dimethyl 2,2'-azobis (isobutyrate), azobis-cyanvaleric acid (ACVA), 1,1'-azobis -(Cyclohexane-1-carbonitrile) (ACHN), 2,2'-azobis- (2,4-dimethylvaleronitrile) (ADVN), azobismethylbutyronitrile (AMBN), 2,2'-azobis- (4-methoxy-2,4-dimethylvaleronitrile) and the like. These can be added to a reaction system (mixed system, contact system) of the polymer and the compound having a nitroxide radical to generate a carbon radical in the polymer. Although there is no restriction | limiting in particular in the addition amount of a radical initiator, Preferably it is 0.1-15 weight part with respect to 100 weight part of polymers, More preferably, it is 0.2-10 weight part.

  Examples of the compound having a nitroxide radical (—N—O.) That is stable at normal temperature in the molecule (hereinafter sometimes referred to as a nitroxide radical derivative) that can be used in the modification method of the present invention include the following compounds. The amount of these compounds to be used is not particularly limited, but is preferably 0.5 to 3.0, more preferably 0.7 to 2.0 parts by weight with respect to the amount of radical initiator added.

  (In the above formulas (1) to (6), R is an alkyl group having 1 to 30 carbon atoms, allyl group, amino group, isocyanate group, hydroxyl group, thiol group, vinyl group, epoxy group, thiirane group, carboxyl group, Carbonyl group-containing groups (for example, cyclic acid anhydrides such as succinic anhydride, maleic anhydride, glutaric anhydride, phthalic anhydride), amide groups, ester groups, imide groups, nitrile groups, thiocyan groups, carbon numbers 1-20 An organic group containing a functional group such as an alkoxy group, a silyl group, an alkoxysilyl group, or a nitro group.

  Other examples are as follows.

  In the polymer modification method of the present invention, the polymer is dissolved or swollen in carbon dioxide in a supercritical state and coexisted with a radical initiator and a nitroxide radical derivative, whereby an organic group (functional group) derived from the nitroxide radical derivative is contained in the polymer. Group) is introduced.

  Examples of the organic group introduced into the polymer by the method for modifying a polymer according to the present invention include an alkyl group having 1 to 30 carbon atoms, a phenyl group, an allyl group, an amino group, an isocyanate group, and a hydroxyl group bonded to a nitroxide radical. , Thiol group, vinyl group, epoxy group, thiirane group, carboxyl group, carbonyl group-containing group (for example, cyclic acid anhydrides such as succinic anhydride, maleic anhydride, glutaric anhydride, phthalic anhydride), amide group, ester Examples thereof include a group, an imide group, a nitrile group, a thiocyan group, an alkoxy group having 1 to 20 carbon atoms, a silyl group, and an alkoxysilyl group.

In the method for modifying a polymer according to the present invention, supercritical carbon dioxide (CO ₂ ) used as a reaction solvent is a gas such as CO ₂ that is a gas at normal temperature and pressure (that is, the boiling point at 1 atm is normal temperature or less). heating, raised or lowered, the liquid state by booster, it is known that can take the gas-liquid mixed state or supercritical state, as the supercritical state of CO ₂ in the present invention, in particular CO ₂ The supercritical state can be obtained by setting the temperature to the critical temperature (31 ° C.) or higher and the critical pressure (7.38 MPa) or higher.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, it cannot be overemphasized that the scope of the present invention is not limited to these Examples.

Examples 1-5
Butyl rubber IIR was used in the form of a string having a diameter of about 1 mm and having a length of about 3 mm. A 500 ml stainless steel cell for high pressure was charged with IIR, OH-TEMPO and DCP in the amounts (parts by weight) shown in Table I, and CO ₂ was added thereto, followed by reaction at the predetermined temperature, pressure and time shown in Table I. . After completion of the reaction, the mixture was allowed to cool, the temperature was lowered to 40 ° C., and the pressure was slowly returned to normal pressure. The obtained modified butyl rubber was taken out of the cell, dissolved in toluene, dropped into a large excess of methanol, aggregated, recovered as modified butyl rubber, and vacuum dried at 40 ° C. for 24 hours. In Examples 3 to 5, the amount of OH-TEMPO shown in Table I was used in advance as a master batch by mechanically kneading with IIR at about 60 ° C. for 3 minutes. The amount of OH-TEMPO grafted was measured by the following method and shown in Table I.

Measurement
Measurement of OH-TEMPO graft amount ¹ H-NMR measurement was performed by NMR (manufactured by Bruker) (accumulation number 128). 3.Integral intensity of signal derived from hydrogen bonded to carbon at position 4 of OH-TEMPO near 3.95 ppm and signal derived from hydrogen bonded to carbon adjacent to double bond of IIR isoprene unit near 5.1 ppm It calculated from the ratio of the integrated intensity (calculated assuming that the isoprene unit contained in IIR is 1.7 mol%).

Example 6
The polypropylene PP used was a spherical pellet having a diameter of about 1 to 2 mm. A 500 ml stainless steel cell for high pressure was charged with PP, OH-TEMPO and DCP in the amounts (parts by weight) shown in Table I, and CO ₂ was added thereto, followed by reaction at the predetermined temperature, pressure and time shown in Table II. . After completion of the reaction, the mixture was allowed to cool, the temperature was lowered to 40 ° C., and the pressure was slowly returned to normal pressure. The obtained modified polypropylene was taken out from the cell, washed in methanol, recovered as modified polypropylene, and vacuum dried at 40 ° C. for 24 hours. The grafting amount of OH-TEMPO was measured by the following method and shown in Table I.

Measurement Measurement of OH-TEMPO graft amount Quantitative determination of nitrogen element contained in the polymer after modification using an elemental analyzer (FlashEA1112 / manufactured by Thermo Electron) and estimating that all N content is derived from TEMPO derivatives. It was.

  As described above, according to the present invention, the modification of the polymer is performed at a relatively low temperature (even a temperature lower than the melting point of the thermoplastic polymer) and with a simple operation without using an organic solvent. Can improve the compatibility of various polymer blends, improve the affinity with various fillers, and improve the adhesion to glass, metal, and different polymer materials. It is useful for use in elastomer materials, cross-linked rubber materials and molded articles using these materials, injection materials (agents), sealing agents and the like.

Claims (6)

  In supercritical carbon dioxide, a polymer that dissolves or swells in carbon dioxide in a supercritical state coexists with a compound having a radical initiator and a nitroxide radical that is a stable radical at room temperature in the molecule, whereby the nitroxide is contained in the polymer. A method for modifying a polymer, wherein an organic group derived from a radical is introduced.   The method for modifying a polymer according to claim 1, wherein the polymer is a crosslinkable rubber.   The method for modifying a polymer according to claim 1, wherein the polymer is a thermoplastic polymer.   The method for modifying a polymer according to any one of claims 1 to 3, wherein the radical initiator is an organic peroxide.   The method for modifying a polymer according to any one of claims 1 to 4, wherein the compound having a nitroxide radical in the molecule is a 2,2,6,6-tetramethylpiperidinyl-1-oxyl derivative.   A polymer modified by the method according to any one of claims 1 to 5.