JP3730719B2 - Process for producing block copolymer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process for the preparation of the novel block copolymers.
[0002]
[Prior art]
In recent years, performance and function requirements for polymer compounds are increasing, and the importance of not only high molecular weight polymers but also graft copolymers and block copolymers has been recognized. . For example, regarding a graft copolymer, a graft copolymer obtained by addition polymerization of a macromonomer has been proposed as disclosed in JP-A-59-75975.
However, in the technique described above, since a dimer as a reaction by-product exists in the macromonomer itself, gelation occurs in the polymerization process; the molecular weight of the macromonomer is tens of thousands or more. In such a case, it is difficult to introduce terminal reactive groups, and unreacted oligomers remain, resulting in failure to obtain desired characteristics; when synthesizing a macromonomer by anionic polymerization, there are types of monomers that can be used. There is a drawback that the degree of freedom of design is limited.
[0003]
On the other hand, Japanese Patent Application Laid-Open No. 62-235310 proposes a method using a peroxide having two types of peroxide bonds having different decomposition temperatures in one molecule.
In this method, although the decomposition temperatures are different, there is a problem that the homogeneity is likely to be generated and the block efficiency is lowered because the radical generation mechanism is repeated although the trigger is heat. In addition, in the first step of polymerization, the growth reaction under heating conditions is continued while leaving a thermally decomposable peroxide bond at the polymer terminal, and therefore gelation occurs when the conversion rate is increased. There's a problem.
[0004]
Further, JP-A-7-179538 proposes a star block copolymer using a polyvalent mercaptan and a production method thereof. However, even by the method described in the above publication, it is difficult to selectively control the generation of radicals from the polyvalent mercaptan, and it is impossible to precisely control the block structure.
[0005]
[Problems to be solved by the invention]
[0006]
The present invention has been made in view of the above problems, and its object is to provide a novel block copolymer that has a high degree of design freedom as a block copolymer and can easily realize desired properties . It is to provide a manufacturing method.
[0007]
[Means for Solving the Problems]
The method for producing a block copolymer of the present invention comprises a compound (I) and a polymerizable monomer (II) having both a functional group having photoradical polymerization initiation ability and a functional group having thermal radical polymerization initiation ability in one molecule. A first step of photoradical polymerization of the polymerizable monomer (II) by irradiating the polymerizable composition with light in a temperature range in which the compound (I) does not undergo thermal decomposition; In the presence of the resulting polymerization product, a polymerizable monomer (III) different from the polymerizable monomer (II) is added, and then the polymerizable monomer (III) is reduced in the decomposition temperature region of the compound (I). The second step of thermal radical polymerization.
[0008]
The block copolymer obtained by the production method of the present invention is a compound (I) having both a functional group having a photoradical polymerization initiation ability and a functional group having a thermal radical polymerization initiation ability in one molecule, as a starting point of polymerization. Two or more different polymers are formed by polymerization.
[0009]
[0010]
The structure of the compound (I) has a functional group having a thermal radical initiating ability capable of decomposing by heating and generating radicals, and a functional group having a photoradical polymerization initiating ability capable of decomposing by light irradiation to generate radicals. There is no particular limitation other than what is being done.
Examples of the functional group having the ability to initiate photoradical polymerization include acetophenone, benzoin, benzophenone, and thioxanthone structure. Examples of the functional group having the ability to initiate thermal radical polymerization include a peroxide bond and an azo bond. The compound (I) includes a compound having a plurality of functional groups that have both thermal radical initiation ability and photoradical initiation ability. For those having such characteristics, a peroxide bond is preferable, and specific compounds are 3,3 ′, 4,4 ′,-tetra- (t-butylperoxycarbonyl) benzophenone [trade name “BTTB”, manufactured by NOF Corporation] and is commercially available.
[0011]
The peroxide bond is decomposed by heat as a normal polymerization initiator, and radicals are easily generated. A high temperature initiator having a proper use temperature range of 100 ° C or higher, a medium temperature initiator of 40 to 100 ° C, Although it can be classified as a low temperature initiator of −10 to 40 ° C. and a cryogenic initiator of −10 ° C. or lower, it is suitable to produce a block polymer efficiently. Those classified as agents are preferred.
[0012]
The polymerizable monomers (II) and (III) used in the present invention are not particularly limited as long as they are radically polymerizable monomers, and may be used alone or in combination of two or more. The polymer part obtained by radical polymerization can be designed in various types of compositions than the polymer part produced by ionic polymerization such as anionic polymerization.
Examples of the polymerizable monomers (II) and (III) include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, sec -Butyl (meth) acrylate, ter-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, iso (Meth) alkyl acrylates such as myristyl (meth) acrylate and isostearyl acrylate; styrene monomers such as α-methylstyrene, vinyltoluene and styrene; methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ester Vinyl ether monomers such as ter; fumaric acid, monoalkyl esters of fumaric acid, fumaric acid ester monomers such as dialkyl esters of fumaric acid; itaconic acids such as itaconic acid, monoalkyl esters of itaconic acid, dialkyl esters of itaconic acid (Meth) acrylonitrile; butadiene; isoprene; vinyl chloride; vinylidene chloride; vinyl acetate; vinyl ketone; vinyl pyrrolidone; vinyl pyridine; (meth) acrylamide; Different monomers can be selected for use.
[0013]
The temperature range in which the compound (I) does not undergo thermal decomposition in the present invention can be set in consideration of the 10-hour half-life temperature generally used as an index representing the decomposition rate of the thermal polymerization initiator. The temperature range set in the present invention is preferably a temperature that is 20 ° C. lower than the 10-hour half-life temperature of the compound (I), more preferably a temperature that is 30 ° C. lower.
When the set temperature range is increased, the compound (I) is thermally decomposed in the first step and gelation is likely to occur, and it is difficult to efficiently obtain the block copolymer that is the original purpose.
[0014]
In addition, the temperature range where the compound (I) undergoes a thermal decomposition reaction can also be set in consideration of the 10-hour half-life temperature, as described above, and should be set to a temperature range higher than the temperature range where the thermal decomposition does not occur. Is possible.
When the set temperature is low, radical polymerization due to thermal initiation in the second step cannot be performed efficiently, and the block ratio of the resulting copolymer decreases.
[0015]
As described above, in the present invention , the polymerizable monomer (II) is photoradically polymerized with the compound (I) to synthesize a polymer, and then the other polymerizable monomer (III) is added to perform thermal radical polymerization. Then, another polymer is synthesized to obtain a block copolymer.
[0016]
Examples of the lamps used for the light irradiation include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, and a meral halide.
[0017]
As a method of heating to the above-mentioned heat partial temperature solution temperature region, a reaction vessel having a heat retaining or heating means such as a normal water bath can be used.
[0018]
The combination of polymer portions having different compositions in the block copolymer obtained by the production method of the present invention can be appropriately determined depending on the performance and use required for the block copolymer. As a combination of polymer parts, a combination of polymer parts derived from polymers having different glass transition temperatures (Tg), a polymer part derived from polymers having different compatibility, and a polymer having different solubility A combination of polymer parts to be produced, a combination of polymer parts derived from a polymer comprising or not containing active hydrogen, and the like.
[0019]
For example, when a polymer part derived from a polymer having a high Tg forms a continuous phase by combining polymer parts derived from polymers having different Tg, molding with high heat resistance and high impact resistance When a block copolymer preferable for a material or a resin for toner is obtained and a polymer portion derived from a polymer having a low Tg forms a continuous phase, a high-strength, high-elongation film, hot-melt adhesive A block copolymer preferable for a thermoplastic elastomer or the like is obtained.
An example of such a block copolymer is a combination of polymethyl methacrylate as a polymer having a high Tg and polybutyl acrylate as a polymer having a low Tg. When the polymer of these combinations is applied to the pressure-sensitive adhesive, it is possible to expect a high degree of compatibility between heat resistance and low temperature sticking property.
[0020]
When polymers having different compatibility are combined, it can be expected to develop into a butadiene rubber dispersant, an impact resistance improving resin or the like in an AS resin (acrylonitrile-styrene copolymer). Further, by combining polymers having different solubility, a water-soluble pressure-sensitive adhesive having both adhesiveness and water-solubility can be obtained.
[0021]
As for the weight average molecular weight of the block copolymer obtained by the manufacturing method of this invention, 1-4 million are preferable, More preferably, it is 200-2 million. If it is less than 10,000, the properties as a polymer cannot be exhibited, and if it exceeds 4 million, the viscosity at the time of production increases and the productivity decreases.
[0022]
A tackifier resin, a plasticizer, a softener, a filler, a stabilizer, an antioxidant, a pigment, a dye, and the like may be added to the block copolymer obtained by the method of the present invention as necessary.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
EXAMPLES Hereinafter, although an Example is hung up and this invention is demonstrated further in detail, this invention is not limited only to these Examples. Hereinafter, “parts” means “parts by weight”.
[0024]
Example 1
(First step: synthesis of polybutyl acrylate)
300 g of n-butyl acrylate monomer (hereinafter referred to as “BA”), 3,3 ′, 4,4 ′,-tetra- (t-butylperoxycarbonyl) benzophenone [trade name “BTTB”, manufactured by NOF Corporation] 29 g, 0.06 g of dodecyl mercaptan (hereinafter referred to as “DDM”), and 245.5 g of ethyl acetate were charged into a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet, and stirred. After dissolving to a homogeneous mixture, it was purged with nitrogen gas for about 20 minutes to remove oxygen present in the monomer solution.
Thereafter, the above homogeneous mixture was bubbled with nitrogen gas and stirred at a rotation of 100 rpm, and polymerization was started by irradiating light with a wavelength of 365 nm with an intensity of 2 mW using a chemical lamp. The polymerization reaction was carried out for 4 hours while keeping the temperature at 40 ° C., starting from the time when the temperature increase was confirmed, to obtain polybutyl acrylate (hereinafter referred to as “PBA”). The conversion rate at the end of the polymerization was 58.2%.
[0025]
(Second step: Synthesis of block copolymer)
285.5 g of an ethyl acetate solution of PBA obtained in the first step was weighed and charged into a five-necked flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel, and a nitrogen gas inlet. 39.26 g of methyl methacrylate monomer (hereinafter referred to as “MMA”) was added so that the solid content ratio of PBA and polymethyl methacrylate (hereinafter referred to as “PMMA”) was 80/20. Further, 32.15 g of ethyl acetate was added as a polymerization solvent so that the total solid content was 55% by weight.
[0026]
After the dissolved oxygen was removed by bubbling nitrogen gas to the monomer and polymer mixed solution for 20 minutes, the inside of the separable flask system was replaced with nitrogen gas, and the monomer mixed solution was stirred using a water bath while stirring at 60 rpm. The temperature was raised to 95 ° C.
The target block copolymer was obtained by carrying out a boiling point polymerization reaction for 4 hours, starting from the time when the reflux liquid was confirmed in the cooling pipe.
The resulting block copolymer had a weight average molecular weight of (Mw) of 420,000 and a polydispersity (Mw / Mn) of 4.10.
[0027]
[0028]
[0029]
[0030]
[0031]
(Comparative Example 1)
480 g of BA, 120 g of PMMA macromonomer (trade name “AA-6”, manufactured by Toa Gosei Co., Ltd .; Mn = 6000), and 490.91 g of ethyl acetate as a polymerization solvent were charged into a separable flask similar to the example. .
Nitrogen gas is used in the monomer mixture solution to remove dissolved oxygen by bubbling for 20 minutes, and then the inside of the separable flask system is replaced with nitrogen gas, and the monomer mixture solution is used with a water bath while stirring at 100 rpm. The temperature rose.
[0032]
When the reflux liquid is confirmed in the cooling pipe, 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane (trade name “Perhexa TMH”, manufactured by NOF Corporation) as a polymerization initiator ) 0.12 g was dissolved and charged in about 1 g of ethyl acetate to initiate boiling point polymerization. After 1 hour, 0.18 g of Perhexa TMH was again dissolved and charged in about 1 g of ethyl acetate.
However, since gelation occurred in the separable flask system at 3 hours after the reaction initiator, the polymerization reaction was terminated.
[0033]
(Comparative Example 2)
480 g of BA, 120 g of MMA, and 490.91 g of ethyl acetate as a polymerization solvent were charged into a separable flask similar to the example.
Nitrogen gas was used for the monomer mixed solution to remove dissolved oxygen by bubbling for 20 minutes, and then the inside of the separable flask system was replaced with nitrogen gas, and the monomer was mixed using a water bath while stirring at 100 rpm. The mixed solution was heated to 95 ° C.
[0034]
When the reflux liquid is confirmed in the cooling pipe, 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane (trade name “Perhexa TMH”, manufactured by NOF Corporation) as a polymerization initiator ) 0.12 g was dissolved and charged in about 1 g of ethyl acetate to initiate boiling point polymerization.
After 1 hour, 0.18 g of Perhexa TMH was again dissolved and charged in about 1 g of ethyl acetate. Further, after 2, 3 and 4 hours from the start of polymerization, about 0.24 g, 0.60 g, and 1.80 g of di (3,5,5-trimethylhexanoyl) peroxide (trade name “Perroyl 355”, manufactured by NOF Corporation) After dissolving and charging in 1 g of ethyl acetate, the target random copolymer was obtained by carrying out boiling point polymerization for 7 hours.
The random polymer had a weight average molecular weight (Mw) of 369,000 and a polydispersity (Mw / Mn) of 2.79.
[0035]
(Measurement of dynamic viscoelastic spectrum)
The dynamic viscoelastic spectra of the block copolymer and the random copolymer obtained in Example 1 and Comparative Example 2 were measured under the following measurement conditions using “DVA-320” manufactured by IT Measurement Control Co., Ltd. It was measured.
Measurement temperature range -40 ~ 120 ℃
Frequency 10Hz
Temperature increase rate 3 ℃ / min
Data acquisition interval 3 ° C
The measurement results by the above method are shown in FIG.
[0036]
From FIG. 1, it can be seen that the block copolymer of the present invention has viscoelastic properties exhibiting low elasticity in the low temperature region and high elasticity in the high temperature region, as compared with a normal random copolymer.
[0037]
【The invention's effect】
According to the present invention , it is possible to synthesize by two-stage polymerization utilizing radical polymerization, and the resulting block copolymer has a high degree of design freedom, and desired characteristics can be easily obtained. Therefore, it can be effectively used for molding resins, hot melt adhesives, thermoplastic elastomers, toner resins, water-soluble adhesives, impact resistance improving resins, compatibilizers, dispersants, and the like.
[0038]
[Brief description of the drawings]
1 is a chart showing measurement results of dynamic viscoelastic spectra of a block copolymer obtained in Example 1 of the present invention and a random copolymer obtained in Comparative Example 2. FIG.

Claims (2)

In one molecule, a polymerizable composition comprising a compound (I) having both a functional group having photoradical polymerization initiating ability and a functional group having heat radical polymerization initiating ability, and a polymerizable monomer (II), the compound (I A first step of photoradically polymerizing the polymerizable monomer (II) by irradiating light in a temperature range where no thermal decomposition occurs),
Subsequently, after adding a polymerizable monomer (III) different from the polymerizable monomer (II) in the presence of the photoradical polymerization product, the polymerizable monomer (III) is added to the compound (I). A method for producing a block copolymer comprising a second step of thermal radical polymerization in a decomposition temperature region. The method for producing a block copolymer according to claim 1, wherein the compound (I) is 3,3 ', 4,4'-tetra- (tert-butylperoxycarbonyl) benzophenone.

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