CN1283681C - Method for preparing isobutylene block copolymer by sequential initiation - Google Patents

Abstract

The invention provides a method for sequentially initiating the preparation of isobutylene block copolymers. The method comprises the following steps in turn: (1) first-stage polymerization: styrene monomer (monomer A) carries out "controllable" or "active" cationic homopolymerization or copolymerization; (2) second-stage polymerization: With isobutene as a monomer, the polymerization product of the first stage is a macromolecular initiator, and a new Lewis acid is added as a co-initiator to carry out homopolymerization of isobutene; or with isobutene as a monomer, the polymerization product of the first stage is A macroinitiator, adding a new Lewis acid as a co-initiator, copolymerizes with a comonomer of isobutylene, thereby obtaining a block copolymer. The invention also provides the isobutylene block copolymer prepared by the method of the invention, its derivatives and applications.

Description

Process for the preparation of isobutylene block copolymers by sequential initiation

technical field

The present invention relates to a kind of preparation method of block copolymer, more specifically, the present invention relates to the cationic polymerization method of the block copolymer of preparation styrenic monomer and isobutylene, the isobutylene block copolymer prepared by this method and its functional derivatives.

Background technique

Block copolymers are a class of copolymers with a definite sequence structure and properties different from random copolymers. Each block in the copolymer has similar physical and mechanical properties to its homopolymer. Block copolymers are widely used as dispersants, surfactants, compatibilizers and thermoplastic elastomers.

The preparation of block copolymers, especially copolymers containing polyisobutylene segments, by living cationic polymerization has been disclosed as follows.

U.S. Patent No. 5,428,111 discloses a method for preparing isobutylene block copolymers, the method comprising: (1) in a mixed solvent of chlorinated hydrocarbons and alkanes, organic tertiary chlorine compounds, TiCl ₄ and 2,6-di-tertiary Butylpyridine is used as an initiating system to carry out living polymerization of isobutylene; (2) adding a capping agent to the above living polymerization system; (3) adding styrene monomers to carry out polymerization. The patent also discloses that the block copolymer prepared by the above method is a thermoplastic elastomer.

Chinese patent 1204653A discloses a living cationic polymerization method for preparing thermoplastic elastomers in which polyisobutylene is a rubber segment, which is characterized in that hexahydropyridine is used as an electron donor or a nucleophile, and dicumyl chloride/ _TiCl is used as an initiating system. A mixture of methyl chloride and cyclohexane was used as the solvent. The preparation process is also the same as first carrying out living cationic polymerization of isobutylene, then adding an end-capping agent, and finally adding styrene monomer to obtain a three-block copolymer. The triblock copolymer can be used as a thermoplastic elastomer.

US Patent No. 5,451,647 discloses an initiator composition for synthesizing isobutylene homopolymers, copolymers and block copolymers consisting of organic tertiary halogen compounds, dimethylaluminum chloride and hindered pyridine.

Chinese patent 1332757 discloses a new tri-block copolymer and its preparation method. The block copolymer is characterized in that its middle soft segment is a random copolymer of isobutylene and vinyl aromatic monomer. The method is to use organic tertiary chlorine compound/dimethylaluminum chloride as an initiating system, and carry out active positive ion polymerization in a mixed solvent composed of chlorinated hydrocarbon and alkane.

However, in the disclosed cationic polymerization processes for the preparation of isobutylene block copolymers, the polymerization of the less reactive monomer isobutene is generally carried out first. The cationic polymerization activity of isobutylene is lower than that of styrenes, and correspondingly stronger Lewis acid is required as a co-initiator. This will inevitably produce a homopolymer of high-activity monomers when adding high-activity monomers. In order to solve this problem, the following methods are generally adopted: (1) use end-capping agents; Nuclear reagent (electron donor). In addition, since polyisobutene is insoluble in chlorinated hydrocarbon solvents such as chloromethane and methylene chloride, which are commonly used in cationic polymerization, at the temperature of cationic polymerization, the activity cannot be achieved in good solvents of polyisobutene (such as linear alkanes and aromatic hydrocarbons). Polymerization, so a mixed solvent must be used. The existence of these problems greatly increases the cost, and at the same time complicates the process, especially the recovery and post-processing. Therefore, there is still a need to find a new method for preparing isobutylene block copolymers.

Contents of the invention

The object of the present invention is to provide a kind of cationic polymerization method of preparing isobutylene block copolymer.

Another object of the present invention is to provide block copolymers prepared by said method and functionalized derivatives thereof.

The block copolymer referred to in this application means that one segment is a random copolymer of polyisobutylene or isobutylene and p-methylstyrene, or a random copolymer of isobutylene and divinylbenzene, and the other segment is a styrene monolayer. homopolymer or copolymer segments.

The styrene-based monomers referred to in this application refer to styrene and its derivatives with substituents on the α-C of styrene or on the benzene ring, including but not limited to styrene, p-methyl Styrene, α-methylstyrene, various alkyl-substituted styrenes, such as p-tert-butylstyrene, p-alkoxystyrene.

A kind of preparation method of isobutylene block copolymer of the present invention comprises steps successively:

(1) The first stage of polymerization: the styrene monomer is subjected to "controllable" or "active" cationic polymerization in the reactor, so that the polymerization reaction is continuously carried out until the conversion rate of the styrene monomer is above 95% by weight;

(2) second-stage polymerization: with the homopolymer or copolymer of the styrene monomer prepared in (1) as a macroinitiator, add the second monomer isobutylene, add co-initiator to initiate the second monomer isobutylene Polymerization, continuous polymerization until the conversion rate of isobutylene is above 90% by weight.

The preparation method of the above-mentioned isobutylene block copolymer is characterized in that the styrenic monomer is styrene or a derivative with a substituent on the α-C of styrene or on the benzene ring, and the substituent is C ₁ to C ₁₅ aliphatic and/or aromatic substituents.

In the preparation method of the above-mentioned isobutylene block copolymer, the comonomer for isobutylene polymerization can be p-methylstyrene and/or divinylbenzene.

In the preparation method of the above-mentioned isobutylene block copolymer, the macroinitiator may be a homopolymer or a copolymer of a styrene monomer whose terminal group is a halogen.

The preparation method of above-mentioned isobutylene block copolymer, its described co-initiator can be Lewis acid, be selected from boron, tin, zinc, aluminum, titanium halide, alkyl halide, alkoxy halide or its One or more than one of the group consisting of mixtures; the preferred co-initiator is dialkylaluminum chloride or dialkylboron chloride.

The cationic polymerization method of the preparation of isobutylene block copolymer of the present application comprises steps successively:

(1) First-stage polymerization: Styrene monomers undergo "controllable" or "living" cationic polymerization or copolymerization in the reactor, and the selection of the polymerization initiation system and polymerization reaction conditions should make the polymerization or copolymerization be "Controlled" or "living" polymerization.

(2) second-stage polymerization: when the above-mentioned polymerization reaction is completed or close to completion, or when the conversion rate of styrene monomer is more than 95% by weight, the polymer prepared in (1) is used as a macroinitiator, and Mixed monomers of isobutylene and/or p-methylstyrene or divinylbenzene with low activity monomers, adding stronger Lewis acid as co-initiator, mixing the above reactants evenly, and initiating isobutylene and/or p-methylstyrene Polymerization of mixed monomers of styrene or divinylbenzene. The polymerization reaction is terminated when the conversion rate of the isobutene monomer is above 90% by weight, and the copolymerized product is recovered, the number average molecular weight is 5000-200000, and the molecular weight distribution is 1.0-2.5.

The cationic polymerization of isobutylene or isobutylene with p-methylstyrene or isobutylene with divinylbenzene can be a "controlled" or "living" cationic polymerization or a conventional cationic polymerization.

The present invention relates to a sequential initiation and sequential addition of monomer phases for the preparation of block copolymers containing polyisobutylene or poly(isobutylene-co-p-methylstyrene) or poly(isobutylene-co-divinylbenzene) segments Combined cationic polymerization method.

The method of the present invention is to first carry out "controlled" or "living" polymerization of styrenic monomers. "Controlled" or "living" cationic polymerization of styrenic monomers can be achieved by various methods, which are described in various literatures, such as "Living cationic polymerization of resonance-stabilized monomers" (Puskas, JE; Kaszas, G.Progress in Polymer Science.2000, 25, 403), "HI/ZnX ₂ Initiated living cationic polymerization of p-methylstyrene" (K.Kojima, M.Sawamoto, Journal of PolymerScience: Part A, Polymer Chemistry, Vol 28, 3007(1990)), et al. In this application, "controllable" or "living" cationic polymerization is defined as: (1) the relative molecular mass of the polymerized product can be determined according to $\stackrel{\‾}{m_{\mathrm{no}}}=\frac{{\left[m\right]}_0}{{\left[I\right]}_0}\×\mathrm{FW}$ OK (where For the number-average relative molecular mass of the polymer, [M] ₀ is the initial concentration of the monomer, [I] ₀ is the initial concentration of the initiator, and FW is the molecular weight of the monomer M); (2) the terminal group of the polymerized product Can be controlled; (3) There is basically no irreversible chain termination and chain transfer reaction during the polymerization reaction. General conditions for "controlled" or "living" cationic polymerization of styrenic monomers include:

(1) The initiator is selected from the group consisting of HX (X=Cl, Br, I), aryl halides such as benzyl chloride, cumyl chloride, 1-phenylchloroethane, 1-phenylbromoethane, cumyl bromide, One or more compounds in the group consisting of benzyl bromide, tert-alkyl halide, tert-alkyl ether, tert-alkyl ester, aralkyl ether, aralkyl ester and mixtures thereof.

(2) The Lewis acid co-initiator is selected from one or more of boron, tin, zinc, aluminum, titanium halides, alkyl halides or alkoxy halides.

(3) Electron donor additives or/and homoionic salt additives, such as ethers, such as ether, methyl tert-butyl ether, etc.; esters such as ethyl acetate, ethyl benzoate, etc.; amides such as N, N- Dimethylformamide, N,N-dimethylacetamide, etc.; quaternary ammonium salts, tetrabutylammonium chloride, tetrabutylammonium bromide, etc. (4) Solvents, selected according to the characteristics of initiators, co-initiators, and monomers, commonly used are chlorinated hydrocarbons such as methyl chloride, methylene chloride, chloroform, ethyl chloride, chloropropane, etc.; alkanes such as cyclohexane Alkanes, substituted cyclohexanes, aromatics such as toluene, benzene, etc.

(5) Monomer or comonomer.

Any known initiator system that can be used for "controllable" or "living" polymerization of styrenic monomers can be applied to the present invention without particular limitation, for example, the review document "Living Cationic Polymerization of Resonance Stabilized Monomer" ( Puskas, J.E.; Kaszas, G. Progress in Polymer Science. 2000, 25, 403) enumerated polymerization systems (but not limited to these systems). However, preferred initiating systems in the present invention are: (1) aryl halides such as benzyl chloride, cumyl chloride, 1-phenylchloroethane, 1-phenylbromoethane, cumyl bromide, benzyl bromide ; (2) co-initiator is tin halide, boron halide, zinc halide, alkyl aluminum or alkyl boron, wherein alkyl is straight chain or branched chain alkyl containing 1-15 carbon atoms; (3) additive is Ionic salts, such as various quaternary ammonium salts; (4) solvents are chlorinated hydrocarbons, such as methyl chloride, methylene chloride, chloroform, ethyl chloride, chloropropane, etc.

The amount of initiator used depends on the relative molecular weight of the prepared copolymer. Usually in the range of 0.0001 mol/L-0.02 mol/L, preferably in the range of 0.0001 mol/L-0.015 mol/L, more preferably in the range of 0.0005 mol/L-0.02 mol/L, especially preferably in the range of 0.0001 mol/L-0.01 mol /l range. The amount of the co-initiator is 1-5 times (moles) of the amount of the initiator, preferably 1-4.5 times (moles), more preferably 1.5-5 times (moles), especially preferably 1-4 (moles). The dosage of the same ion salt of the additive is generally 0.1-5 times (mol) of the initiator, preferably 0.5-5 times (mol), more preferably 1.0-5 times (mol), especially preferably 1-4.5 times (mol) .

In the method of the present invention, the homopolymer or copolymer of styrenic monomers prepared by the above method is used as a macroinitiator, and then isobutylene or isobutylene and p-methylstyrene or divinylbenzene are added. The body is another block monomer, and a new co-initiator is added to carry out homopolymerization or copolymerization of isobutylene. The polymerization process of polyisobutylene or poly(isobutylene-co-p-methylstyrene) or poly(isobutylene-co-divinylbenzene) blocks can be "controlled" or "living" cationic polymerization, or conventional cationic polymerization. Therefore, any co-initiator that can be combined with the homopolymer or copolymer of styrenic monomer prepared by the above-mentioned method to form isobutylene polymerization or isobutylene and p-methylstyrene or divinylbenzene copolymerization can be used in this invention. invention. These co-initiators include, but are not limited to: boron halides and alkyl halides, aluminum halides and alkyl halides, titanium halides, VCl ₄ , SbF ₅ , etc. Among them, alkyl chlorides of boron and aluminum are preferable, and dialkylaluminum chloride or dialkylboron chloride are more preferable. The amount of co-initiator used for isobutylene polymerization or copolymerization is 1-5 times (mole) of the amount of styrene monomer polymerization initiator. During the second stage of polymerization, additional solvent may or may not be added. The additional solvent may be the same as or different from the solvent used in the first-stage polymerization.

The temperature of the polymerization reaction adopted in the present invention should be lower than 0 ℃, preferably-10 ℃～-115 ℃, the selection of polymerization temperature and polymerization time should be enough to prepare the multipolymer of required relative molecular mass, these selections are well known to those skilled in the art. Polymerization can be carried out in conventional reactors or vessels, such as those used for the production of butyl rubber and polyisobutylene.

Examples of block copolymers prepared according to the present invention include (but are not limited to): polystyrene-b-polyisobutylene, polyp-methylstyrene-b-polyisobutylene, polystyrene-b-poly(isobutylene-co - p-methylstyrene), polystyrene-b-poly(isobutylene-co-p-divinylbenzene), poly(styrene-co-p-methylstyrene)-b-polyisobutylene, poly(styrene -co-p-methylstyrene)-b-poly(isobutylene-co-p-methylstyrene), poly(styrene-co-p-methylstyrene)-b-poly(isobutylene-co-divinyl benzene), poly(styrene-co-divinylbenzene)-b-poly(isobutylene-co-p-methylstyrene), poly(p-methylstyrene-co-divinylbenzene)-b-poly (isobutylene-co-p-methylstyrene), poly(α-methylstyrene)-b-poly(isobutylene-co-p-methylstyrene), poly(α-methylstyrene)-b-poly Isobutylene, poly(alpha-methylstyrene)-b-poly(isobutylene-co-p-methylstyrene) and poly(alpha-methylstyrene)-b-poly(isobutylene-co-divinylbenzene) wait.

In addition, for copolymers containing p-methylstyrene structural units, derivatives can be prepared by halogenation, functionalization or grafting as known in the art. These functionalized block copolymers offer improved adhesion, compatibility, lyophilicity, and dispersibility compared to unfunctionalized polymers, as well as multiple crosslinking reactions, including UV crosslinking , electron beam radiation, free radicals and carbenium ion chemical crosslinking. These modified functionalized block copolymers are useful in compositions with adhesives, coatings, molded articles, polymer blends and as emulsifiers for emulsion polymerization and dispersion polymerization of non-aqueous systems.

Description of drawings

Figure 1 is a schematic diagram of the process for preparing a block copolymer of the present invention.

Detailed ways

The present invention prepares the technological process of block copolymer as shown in Figure 1:

The first-stage polymerization reaction time should guarantee that the monomer transformation rate of the first-stage polymerization is greater than 95% by weight, and the specific polymerization reaction time is related to styrene monomer and co-monomer, initiator, co-initiator, polymerization temperature and solvent It should be selected according to the nature of the system. The polymerization reaction time of the second stage should also ensure that the polymerization conversion rate of isobutylene monomer or isobutylene and comonomer is greater than 95% by weight, and the specific polymerization reaction time is related to the properties of monomers, comonomers and co-initiators.

Using the method of the present invention, block copolymers with the following characteristics can be prepared: (1) relative molecular mass distribution of about 1.0 to 2.5; (2) molecular weight of about 5,000 to 200,000; (3) containing 0% polyisobutylene in the polyisobutylene block to 50% by weight of p-methylstyrene monomer structural units, and 0% to 2.5% by weight of divinylbenzene structural units. As is well known in the art, the copolymeric composition of block copolymers, including the molecular weight of each block and the copolymeric composition and degree of crosslinking of the different blocks depends on the use and desired properties of the polymer. Likewise, the nature of the functional groups and the degree of functionalization of the functionalized block copolymers will also depend on the use and desired properties of the polymer.

The block copolymers prepared by the present invention can be used in many fields, including adhesives, dispersants, dispersion polymerization of non-aqueous systems (such as used to stabilize polymer slurry in the production of butyl rubber), emulsion polymerization Emulsifier, compatibilizer for blended polymer compositions, molded products, dynamically vulcanized rubber, etc.

The present invention can be better understood with reference to the following examples, but the present invention is not limited by these examples.

Example 1

Add 30ml of methyl chloride into a dry nitrogen-filled reactor, then add about 60mgn-Bu ₄ N ⁺ Cl ^- , 2.06g p-methylstyrene, 18 microliters of 1-phenylethyl chloride, and cool the reaction mixture to -40 °C, then add 50 µl of SnCl ₄ to start the first stage of polymerization. After 1 hour of polymerization reaction, a small amount of sample was taken to determine the relative molecular mass of poly-p-methylstyrene. Next, 2.04 g of isobutene was added, cooled to -80°C, and 0.2 ml of AlEt ₂ Cl (10 M hexane solution) was added to carry out the second-stage polymerization. After 30 minutes of polymerization, 2 ml of methanol was added to terminate the polymerization, the polymer was precipitated with methanol, and about 4.0 g of the polymer was obtained after drying. The number average relative molecular mass measured by GPC was 19200 (MWD=1.46) for poly-p-methylstyrene, and 36600 (MWD=1.42) for poly-p-methylstyrene-b-polyisobutylene.

Example 2

Add 20ml of methyl chloride into a dry nitrogen-filled reactor, then add about 25mg of n-Bu ₄ N ⁺ Cl ^- , 1.5g of p-methylstyrene, and 15 microliters of 1-phenylethyl chloride, and the reaction mixture Cool to -40°C, then add 50 μl of SnCl ₄ to start the first stage of polymerization, and polymerize for 1 hour. Next, 1.8 g of isobutene and 18 mg of divinylbenzene were added, cooled to -80°C, and 0.1 ml of AlEt ₂ Cl (10M hexane solution) was added to carry out the second-stage polymerization. After 30 minutes of polymerization, 2 ml of methanol was added to terminate the polymerization, the polymer was precipitated with methanol, and about 3.2 g of the polymer was obtained after drying. There are about 10% cyclohexane insoluble matter in the polymer product, and the number-average relative molecular mass of the soluble part measured by GPC is 25300 (MWD=4.13), and the GPC spectrum shows double peaks. This indicates that the poly(isobutylene-co-divinylbenzene) part has undergone a cross-linking reaction.

Example 3

Add 30ml of dichloromethane into a dry nitrogen-filled reactor, then add about 25mgn-Bu ₄ N ⁺ Cl ^- , 1.8g styrene, 15 microliters of 1-phenylethyl chloride, and cool the reaction mixture to - 40°C, then add 200 microliters of SnCl ₄ to start the first-stage polymerization, and the polymerization reaction takes 4 hours. Next, 1.8 g of isobutylene and 100 mg of p-methylstyrene were added, cooled to -80°C, and 0.1 ml of AlEt ₂ Cl (10M hexane solution) was added to carry out the second-stage polymerization. After 30 minutes of polymerization, 2 ml of methanol was added to terminate the polymerization, the polymer was precipitated with methanol, and about 3.67 g of polymer was obtained after drying. The number average relative molecular mass determined by GPC is 35300 (MWD=1.65), and the content of p-methylstyrene in the polyisobutylene block determined by ¹ H-NMR is about 5.2% by weight.

Example 4

10 grams of poly-p-methylstyrene-b-polyisobutylene (the number-average relative molecular mass of poly-p-methylstyrene segment is 24000, MWD=1.42, and the number-average relative molecular mass of diblock copolymer is 46000, MWD =1.45) was dissolved in 80 milliliters of CCl ₄ , added 2 milliliters of bromine, 100 milligrams of AIBN, and reacted at 60° C. for 3 hours, then precipitated with water, and obtained about 12 grams of polymer after drying. According to ¹ H-NMR measurement, about 76.3 mol% of the methyl groups in the p-methylstyrene structural units in the poly-p-methylstyrene block are brominated.

Example 5

Weigh about 6 g of brominated poly-p-methylstyrene-b-polyisobutylene, and add 40 ml of toluene to dissolve it. Dissolve 3 ml of triethylamine in 10 ml of isopropanol and add to the toluene solution of parylene-b-polyisobutylene under stirring. Then react at about 86°C for 3 hours. The obtained product was precipitated in isopropanol, and after drying, the result measured by ¹ H-NMR showed that nearly 100% (molar ratio) of brominated p-methylstyrene structural units formed quaternary ammonium salts. Quaternized poly-p-methylstyrene-b-polyisobutylene is dissolved in chloroform, methylene chloride, n-hexane, toluene, styrene, etc. to form a milky solution. Adding water to the above milky solution can form a stable emulsion.

Example 6

About 0.2 gram of polyp-methylstyrene-b-polyisobutylene prepared in Example 1 was dissolved in 100 milliliters of butyl rubber produced compound [the content of isobutylene and isoprene was 31.8% by weight, and the rest was Chloromethane]. Then the mixture was cooled to -100°C, and 10 ml of AlCl ₃ in methyl chloride solution (containing about 25 mg of AlCl ₃ ) was added under stirring. The polymerization product is a white emulsion, which remains in the emulsion state when the temperature is naturally raised to -50°C under stirring. Ethanol was added for precipitation to obtain 25 g of a polymer product.

As stated above, the present invention has been clearly and completely described, and these are illustrative illustrations of the aspects of the invention. However, it is very clear that those skilled in the art can make various improvements or modifications to the present invention without departing from the spirit of the present invention, and these should be included in the scope of the present invention. The scope of the invention will be set forth in the appended claims.

Claims (5)

1. a preparation method of isobutylene block copolymer, the method comprises steps successively: (1) The first stage of polymerization: the styrene monomer is subjected to "controllable" or "active" cationic polymerization in the reactor, so that the polymerization reaction is continuously carried out until the conversion rate of the styrene monomer is above 95% by weight; (2) second-stage polymerization: with the homopolymer or copolymer of the styrene monomer prepared in (1) as a macroinitiator, add the second monomer isobutylene, add co-initiator to initiate the second monomer isobutylene Polymerization, continuous polymerization until the conversion rate of isobutylene is more than 90% by weight; the co-initiator is a Lewis acid selected from boron, tin, zinc, aluminum, titanium halides, alkyl halides, alkoxy halides or One or more of the group consisting of mixtures thereof. 2. by the preparation method of the isobutylene block copolymer described in claim 1, it is characterized in that styrenic monomer is styrene or on the α-C of styrene or the derivative that has substituent on the benzene ring, The substituents are _C1 to _C15 aliphatic and/or aromatic substituents. 3. by the preparation method of the isobutylene block copolymer described in claim 1, it is characterized in that the comonomer of isobutylene polymerization is p-methylstyrene and/or divinylbenzene. 4. by the preparation method of the isobutylene block copolymer described in claim 1, it is characterized in that described macromolecular initiator refers to the homopolymer or the copolymer of the styrenic monomer that terminal group is a halogen. 5. by the preparation method of the isobutylene block copolymer described in claim 1, it is characterized in that described co-initiator is dialkylaluminum chloride or dialkylboron chloride.

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