JP3377916B2 - Vinyl ester polymer and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vinyl ester polymer having a precisely controlled primary structure and a method for producing the same. More specifically, the present invention relates to a vinyl ester polymer having a controlled molecular weight, and a vinyl ester polymer having a narrow molecular weight distribution (ratio of weight average molecular weight to number average molecular weight).

[0002]

BACKGROUND ART Vinyl ester polymers can be industrially produced by radical polymerization, as represented by polyvinyl acetate. However, in general radical polymerization, many reactions such as recombination, termination reaction such as disproportionation, and side reactions such as chain transfer occur, so that the obtained vinyl ester polymer has a wide molecular weight distribution, and the molecular weight can be controlled arbitrarily. However, it was difficult to control the terminal group and synthesize the block polymer.

It has been reported that vinyl acetate can also be polymerized by cationic polymerization, but only low molecular weight vinyl acetate has been obtained, and there is no report on the control of the primary structure of the polymer. However, it was difficult to obtain the polymer industrially.

It is essential to control the molecular weight and molecular weight distribution of a vinyl ester polymer, to control the terminal group of the vinyl ester polymer, and to form a block polymer in order to achieve high functionality and high performance. Is. That is, by controlling the molecular weight, for example, mechanical strength, flow characteristics, thermal stability, compatibility with other resins, plasticization efficiency,
It is possible to control the dispersion stabilizing effect.

Further, a polymer having a narrow molecular weight distribution and containing no low molecular weight component is expected to improve the adhesive performance, mechanical strength, flow characteristics and the like. In addition, by controlling the molecular weight distribution, the dynamic viscoelastic property can be designed to be specifically high in a specific temperature range and frequency range, and compatibility can be controlled.

Regarding the control of the molecular weight distribution, for example, Japanese Patent Publication No. 7-13094 discloses a technique of controlling the molecular weight distribution to some extent by radical polymerization of vinyl acetate. This technique relates to the polymerization of polyvinyl acetate, which has a low molecular weight and a narrow molecular weight distribution, by skillfully using chain transfer and addition of monomers. This is a method in which polyvinyl acetate having an extremely low molecular weight is obtained while charging and then saponified to obtain polyvinyl alcohol.

However, the molecular weight distribution of polyvinyl acetate obtained by using this technique is not yet at a satisfactory level, and the sequential addition of monomers complicates the operation, and the number of polymers obtained. Average molecular weight (Mn)
Was limited to as low as 13200 or less.

As means for solving these technical problems,
For example, living radical polymerization is considered. If living radical polymerization is used, it is possible to control the molecular weight, control the molecular weight distribution, control the molecular end groups, etc., and obtain a block polymer. In particular, various monomers such as styrene, methacrylate, and acrylate have been extensively studied, and their unique living radical polymerization systems have been studied, and it is widely known that the primary structure of the polymer can be controlled to some degree of precision. Has become.

However, since the reactivity varies greatly depending on the monomer, a method applicable to any monomer has not been found yet. In particular, in the case of vinyl acetate, chain transfer is likely to occur because the chain transfer constant is 100 times or more larger than that of the above-mentioned styrene and methacrylate monomers, and further, the resonance stabilizing effect of electrons is low and the growth radical is unstable. However, side reactions are likely to occur, and the precise control thereof is generally considered to have a very high technical barrier as compared with other monomers, and the problem has not yet been solved.

Regarding the precise control of the primary structure with respect to the styrene monomer, JP-A-7-126322 discloses carbon-
It is described that a polymer having a relatively narrow molecular weight distribution can be obtained in the presence of an iodine compound having an iodine bond and a radical polymerization initiator. However, this is not related to a vinyl ester polymer, and a polymer having a too high molecular weight cannot be obtained, and it is difficult to obtain a polymer material exhibiting physical properties.

A report similar to that of the above-mentioned Japanese Patent Laid-Open No. 126322/1995 has been reported in [[Macromolecules, vol. 28, page 8051-8056].
(1995)], it is shown that a polymer that can be controlled to some extent can be obtained for styrene monomer and acrylate monomer, but no polymer is obtained for vinyl acetate monomer. There is a report.

Regarding living radical polymerization of vinyl acetate, reference [Macromolecules, vol.27, page 645-649 (1994)].
Describes that it is possible with a catalyst system consisting of a ternary system of triisobutylaluminum, 2,2'-dipyridyl and 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO). . However, it is necessary to use a metal complex that is unstable to air and water as a catalyst system, and the presence of trace amounts of oxygen and water impairs the reproducibility of polymerization and is not suitable for industrialization.

Further, polyvinyl alcohol, polyvinyl acetal resin and the like are industrially obtained by modifying a vinyl acetate polymer. Therefore, since there is no precise polymerization technique for vinyl acetate, it is not possible to industrially obtain a derivative such as polyvinyl alcohol or polyvinyl acetal resin in which the primary structure of the polymer is precisely controlled.

[0014]

SUMMARY OF THE INVENTION The present invention solves the above problems and provides a vinyl ester polymer having a precisely controlled primary structure, which has been difficult until now, and a method for producing the same. To aim. That is, the present invention provides a vinyl ester polymer having a narrow molecular weight distribution and a method for producing the vinyl ester polymer that is easy to industrialize.

[0015]

The vinyl ester polymer of the present invention is a vinyl ester monomer having 3 to 20 carbon atoms.
A polymer obtained by polymerizing ( excluding aromatic carboxylic acid vinyl ester), and having a molecular weight distribution [weight average molecular weight (Mw) / number average molecular weight (Mn)] of 1.05
It is 1.68 and Mn is 6,600 or more .

The inventors of the present invention have made earnest studies for the purpose of precisely controlling the primary structure of a vinyl ester polymer, and by adding a specific iodine compound to an ordinary radical polymerization system, The inventors have found that the obtained polymer has a narrow molecular weight distribution, and completed the present invention.

The vinyl ester polymer of the present invention is obtained by radically polymerizing a vinyl ester monomer having 3 to 20 carbon atoms in the presence of a specific iodine compound, and its molecular weight distribution (Mw / Mn) is 1.05-1.
It is limited to 9 and is preferably 1.05 to 1.8.

The vinyl ester polymer having a molecular weight distribution of less than 1.05 is difficult to obtain by actual production. When the molecular weight distribution exceeds 1.9, for example,
The ratio of low molecular weight components increases, and the adhesiveness, mechanical strength,
It becomes difficult to improve the flow characteristics and the like. The molecular weight distribution described in the example of JP-B-7-13094 is 2.1.

Examples of the vinyl ester-based monomer having 3 to 20 carbon atoms used in the vinyl ester-based polymer include vinyl acetate, vinyl formate, vinyl propionate,
Vinyl butyrate, n- caproic acid vinyl, vinyl isocaproic acid, vinyl octanoate, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl trimethyl acetate, vinyl chloroacetate, vinyl trichloroacetic acid, trifluoroacetic acid vinyl le, and the like These may be used alone or in combination of two or more. Among these, vinyl acetate is particularly preferably used.

It is also possible to copolymerize by using a monomer other than the vinyl ester type together.

The vinyl ester polymer can be obtained by radically polymerizing the vinyl ester monomer in the presence of an iodine compound. The vinyl ester-based monomer may be added to the polymerization solution in its entirety from the beginning,
It may be added sequentially as the polymerization progresses.

Examples of the iodine compound used in the present invention include compounds having at least one bond selected from carbon-iodine bond, hydrogen-iodine bond and halogen-iodine bond in the molecule.

Examples of the compound having a carbon-iodine bond include alkyl iodide, perfluoroalkyl iodide, phenyl iodide and the like.

Specific examples of the alkyl iodide include iodomethane, iodoethane, iodopropane, iodobutane, diiodomethane, 1,2-diiodoethane, iodoform, chloroiodomethane, iodoacetonitrile, iodoacetic acid, 1,6-diiodohexane, iodoacetate. Examples include acetamide, products obtained by addition reaction of hydrogen iodide with alkenes, and the like.

Specific examples of the alkenes include vinyl ester type monomers such as vinyl acetate; vinyl ether type monomers such as isobutyl vinyl ether; styrene type monomers. Examples of the method for the addition reaction of hydrogen iodide with an alkene include a method of mixing anhydrous hydrogen iodide with an alkene at a low temperature.

Specific examples of the above-mentioned perfluoroalkyl iodide include iodoperfluoropropane, 1-iodoperfluorohexane, 1-iodoperfluorooctane,
Examples thereof include 1,2-diiodoperfluoroethane, 1,4-diiodoperfluorobutane, and 1,6-diiodoperfluorohexane.

Specific examples of the phenyl iodide include iodobenzene and 2-iodoethylbenzene.

Examples of the compound having a hydrogen-iodine bond include hydrogen iodide and the like. Examples of the compound having a halogen-iodine bond include iodine monochloride, iodine trichloride, iodine monobromide and the like.

The above iodine compounds may be used alone or in combination of two or more kinds. More preferably among the above iodine compounds, iodoform, diiodomethane, alkyl iodides such as iodoacetonitrile, 1-iodoperfluorohexane, 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane and the like. Perfluoroalkyl iodide; adduct of hydrogen iodide and alkene; hydrogen iodide.

From the viewpoint of controlling the number average molecular weight, iodoform is preferably used as the iodine compound. In the reaction in the presence of the iodine compound, it is possible to predict the number average molecular weight, assuming that one molecule of the polymer is produced from one molecule of the iodine compound. When iodoform is used as the iodine compound, the predicted value (by calculation) and the result of the obtained polymer match well, which is advantageous in controlling the number average molecular weight of the polymer.

The amount of the iodine compound is appropriately determined according to the molecular weight of the polymer to be obtained, but if the amount of the iodine compound is too small, the structure of the polymer cannot be controlled and is too large. Therefore, a polymer cannot be obtained, so 0.001 per mol of vinyl ester monomer
It is preferable to add at a ratio of 01 to 0.2 mol,
More preferably, the proportion is 0.0005 to 0.1 mol with respect to 1 mol of the vinyl ester monomer.

The method of adding the above-mentioned iodine compound is not particularly limited, but it is preferable to add it to the polymerization system before the initiation of the polymerization, from the viewpoint of controlling the molecular weight distribution and easiness of operation.

The molecular weight of the vinyl ester polymer is
It can be adjusted by the concentration of the iodine compound, and the number average molecular weight is preferably 6,600 to 500,000, more preferably the number average molecular weight is 6,600 to 200,000 .
This is because if the number average molecular weight exceeds 500,000, handling becomes difficult.

According to the present invention, it is possible to easily obtain a vinyl ester polymer having a low molecular weight and a narrow molecular weight distribution, which has been difficult to realize by a conventionally known technique.

Examples of the radical polymerization method in the present invention include the use of a radical polymerization initiator; the use of a photosensitizer and the irradiation of light; the irradiation of radiation, laser light, light, etc .; Industrially, a method using a radical polymerization initiator is preferable.

The radical polymerization initiator is not particularly limited as long as it can generate radicals and react with the vinyl ester-based monomer and the iodine compound to cause a polymerization reaction. It is selected from compounds that generate radicals by the action of radiation, redox chemical reactions and the like.

Examples of the radical polymerization initiator include azo compounds, organic peroxides, inorganic peroxides, organic metal compounds,
Examples include photosensitizers and redox polymerization initiators.

Examples of the azo compound include azobisisobutyronitrile (hereinafter referred to as AIBN), azobisisobutyric acid ester, and hyponitrite. Examples of the organic peroxide include benzoyl peroxide (hereinafter referred to as BPO), lauroyl peroxide, dicumyl peroxide, dibenzoyl peroxide and the like. Examples of the inorganic peroxide include potassium persulfate and ammonium persulfate.

Examples of the redox polymerization initiator include hydrogen peroxide-ferrous iron type, BPO-dimethylaniline type, cerium (IV) salt-alcohol type and the like.
Examples of the organometallic compound include compounds containing a Group 2 or Group 3 metal and lead.

Among these radical polymerization initiators, AIBN and BPO are particularly preferably used.

In the case of radical polymerization by light, a photosensitizer such as an azo compound, a peroxide, a carbonyl compound, a sulfur compound and a dye may be added.

The above radical polymerization initiators may be used alone, or two or more of them may be used in combination so long as the interaction does not adversely affect the progress of polymerization. In addition, the radical polymerization may be used in combination with a plurality of methods, such as preliminarily advancing the polymerization to a certain extent by the action of heat and then completing the polymerization with light.

The amount of the radical polymerization initiator used is not particularly limited as long as it is an amount that initiates polymerization.
When the amount is low, the polymerization reaction is slow and the polymerization rate is low,
Since it becomes difficult to control the polymerization reaction when the number increases,
0.02 to 20 per 1 mol of iodine compound used
mol is preferable, and more preferably 0.05 to 10 mo.
It is l. Particularly, it is preferable to use the radical initiator in the range of 0.1 to 5 mol with respect to 1 mol of the iodine compound.

The amount of the radical polymerization initiator used is 0.0000 with respect to 1 mol of the vinyl ester monomer.
5 to 0.5 mol is preferable, more preferably 0.00
It is 01 to 0.2 mol.

The polymerization temperature varies depending on the type of radical polymerization reaction and is not particularly limited, but is preferably -30 ° C to 120 ° C, more preferably 0 ° C to 100 ° C. The reaction pressure is usually atmospheric pressure, but it may be increased.

As the polymerization method according to the present invention, a conventionally known method can be used, for example, lump, solution, suspension,
Emulsion polymerization etc. are mentioned. In particular, bulk polymerization is preferably used from the viewpoint of suppressing chain transfer and obtaining a more well-controlled vinyl ester polymer. Further, the polymerization may be continuously carried out using an extruder.

The solvent for solution polymerization is alcohol,
Toluene, benzene and the like can be used, but benzene, which has a relatively small chain transfer constant during polymerization of the vinyl ester-based monomer and is excellent in polymer solubility, is particularly preferably used.

Most of the initiation terminals of the vinyl ester polymer obtained by the present invention are alkyl groups, perfluoroalkyl groups, phenyl groups and the like derived from iodine compounds, and most of the growth terminals are iodine. It has been confirmed. Therefore, by using an iodine compound having a functional group, a functional group can be introduced at the terminal of the polymer. Also, by utilizing the reactivity of the terminal functional group and iodine,
Conversion to other functional groups is also possible. These end-functional polymers can be used as a macromonomer synthesis and crosslinking point, and can be used as a compatibilizer, a raw material of a block polymer, and the like.

In order to improve the stability of the above vinyl ester-based polymer, methanol, ammoniacal methanol, lithium borohydride, etc. are added to the polymerization system at the time of termination of the polymerization to remove iodine existing at the growth end of the polymer. May be separated. Further, the obtained polymer may be irradiated with ultraviolet rays in the presence of isopentane or the like to stabilize iodine with hydrogen.

After obtaining the above vinyl ester-based polymer, other monomers are added to the polymerization system and polymerized,
It is also possible to obtain a block copolymer. In addition to block copolymers of different vinyl ester-based monomers, it is also possible to obtain block copolymers of vinyl ester-based monomers and styrene-based, acrylic-based, methacrylate-based monomers and the like.

As the above iodine compound, a hyperbranched polymer can be obtained by using an iodine compound having a plurality of iodines capable of participating in the polymerization or by adding a small amount of various divinyl monomers in the latter stage of the polymerization and crosslinking the same. Is also possible.

The obtained vinyl ester polymer is partially or wholly saponified by a conventionally known method,
Partially saponified polyvinyl alcohol and polyvinyl alcohol can be obtained.

Further, it can be used as a compatibilizer or the like by converting into various polymers by utilizing the reactivity of the hydroxyl group possessed by the polyvinyl alcohol obtained above, the hydrogen bonding ability and the like. In particular, a polyvinyl acetal can be obtained by acetalization by a conventional method.

Further, it is possible to obtain a polymer having a functional group at the terminal as a vinyl ester polymer. Utilizing such an end group, synthesis of a macromonomer, use as a crosslinking point, synthesis of a block polymer. Etc. are possible.
With such a block polymer, a polymer exhibiting new physical properties different from the homopolymerization of monomers can be obtained. For example, a thermoplastic elastomer can be obtained as a triblock copolymer such as ABA.

[0055]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below based on Examples and Comparative Examples. (Example 1) AIBN (radical polymerization initiator) is 180
mmol / l, iodoform 90 mmol / l, vinyl acetate monomer (indicated by monomer in the table) 9 mol / l
1.2 mol of l, n-heptane (for GPC internal standard)
The polymerization solution was adjusted so as to be 1 / l, and the mixture was uniformly mixed at 0 ° C., then 1 ml was dispensed / sealed in a test tube and heated to 60 ° C. to start polymerization. After reacting for 4 hours, the polymerization liquid was cooled to −78 ° C. to stop the polymerization. The polymer solution was diluted with toluene and then precipitated in n-hexane, the precipitate was washed several times, and dried under reduced pressure at room temperature to obtain a polymer.

(Examples 2 to 18 and Comparative Examples 1 to 4) Predetermined amounts of the radical polymerization initiator, iodine compound and vinyl acetate monomer shown in Tables 1 to 3 were charged in the same manner as in Example 1 and uniformly mixed. After that, polymerization was carried out at the temperatures and reaction times shown in Tables 1 to 3, and the obtained polymerization liquid was treated in the same manner as in Example 1 to obtain a polymer.

Unless otherwise noted, monomers, solvents and the like were used after deoxidation treatment after removing polymerization inhibitors and impurities by distillation purification.

The following measurements were performed on the polymers obtained in the above Examples and Comparative Examples, and the measurement results are shown in Tables 1 to 3. (1) Method of measuring polymerization rate The polymerization rate was gas chromatography (manufactured by Shimadzu Corporation, column: PEG1500) using n-heptane as an internal standard.
Used). (2) Method of measuring molecular weight The number average molecular weight (Mn) and the weight average molecular weight (Mw) are
Gel permeation chromatography (GPC)
[GPC: JASCO Corporation, column: Showa Denko KK "polystyrene gel 805L", solvent: chloroform, flow rate:
1 ml / min], and measured in terms of polystyrene.
The molecular weight distribution (MW / Mn) was calculated from the number average molecular weight (Mn) and the weight average molecular weight (Mw) measured above.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

[Table 3]

In Tables 1 to 3, the following materials were used. [Iodine compound] a: iodoform b: diiodomethane c: hydrogen iodide adduct of vinyl acetate d: hydrogen iodide e: 1-iodoperfluorohexane f: 1,6-diiodoperfluorohexane g: iodine monochloride h : Chloroform i: Bromoform

[Radical Polymerization Initiator] A: Azobisisobutyronitrile B: Benzoyl peroxide

In the table, M is a vinyl acetate monomer, I is an iodine compound, and P is a radical polymerization initiator. Mn: number average molecular weight Mw / Mn: molecular weight distribution (weight average molecular weight / number average molecular weight)

In Example 7 , a high pressure mercury lamp (200
w) was irradiated from a distance of 9 cm, benzene was added in Example 13 and toluene was added in Example 14 as a solvent. In Example 16 , after the operation of Example 15 , 9 mol of vinyl acetate monomer was added again to carry out polymerization. It lasted for 7 hours.

[0066]

INDUSTRIAL APPLICABILITY As described above, the vinyl ester polymer of the present invention is capable of controlling the molecular weight, the molecular weight distribution, the terminal group, etc. because the primary structure is precisely controlled. It is possible to achieve higher functionality and higher performance. In particular, by controlling the molecular weight, mechanical strength, flow characteristics, thermal stability, compatibility with other resins, plasticization efficiency and the like can be freely controlled. Further, by controlling the molecular weight distribution, for example, by narrowing the molecular weight distribution to reduce the low molecular weight components, it is possible to improve the adhesiveness, the mechanical strength, the flow characteristics and the like.

The method for producing a vinyl ester-based polymer of the present invention is a method for industrially easily producing a vinyl ester-based polymer, a block copolymer or the like having a controlled molecular weight, a narrow molecular weight distribution and a controlled terminal group. It is possible to provide, and by modifying these, derivatives such as polyvinyl alcohol and polyvinyl acetal can be obtained.

Claims (6)

(57) [Claims] 1. A polymer obtained by polymerizing a vinyl ester monomer having 3 to 20 carbon atoms (excluding aromatic carboxylic acid vinyl ester) , which has a molecular weight distribution [weight average molecular weight (Mw)]. / Number average molecular weight (Mn)] is 1.05
The vinyl ester polymer has a Mn of 1,600 or more and a Mn of 6,600 or more . 2. A vinyl ester polymer obtained by radical polymerization of an iodine compound added to a vinyl ester monomer. 3. The iodine compound is an iodine compound having at least one bond selected from carbon-iodine bond, hydrogen-iodine bond and halogen-iodine bond in the molecule. Vinyl ester polymer. 4. The vinyl ester polymer according to claim 1, wherein the vinyl ester monomer is vinyl acetate. 5. The vinyl ester polymer according to any one of claims 1 to 4, wherein the vinyl ester monomer is radically polymerized in the presence of a radical polymerization initiator and an iodine compound. Manufacturing method. 6. Addition so that the molar ratio of the iodine compound to the vinyl ester monomer is 5 × 10 ^{−4 to} 0.1 and the molar ratio of the radical polymerization initiator to the iodine compound is 0.1 to 5. The method for producing a vinyl ester polymer according to claim 5, wherein the radical polymerization is performed.