JPH03212402A - Preparation of styrenic resin - Google Patents

Abstract

PURPOSE:To profitably prepare the subject resin having a low average mol.wt. without requiring a solvent and a large amount of a polymerization initiator by polymerizing a styrenic monomer in the presence of a double bond-containing chain transfer agent and a specific organic peroxide by a specified method. CONSTITUTION:(A) A styrenic monomer or a mixture thereof with a copolymerizable vinylic monomer and (B) an organic peroxide (e.g. di-n- propylperoxydicarbonate) having a 10 hour half life temperature (0.1mol/l in benzene) of 35-75 deg.C are continuously or intermittently added to a system containing (C) a double bond-containing chain transfer agent (e.g. alpha- methylstyrene dimer) for 0.5-10 hours at a temperature 10-50 deg.C higher than the 10 hour half life temperature of the component B, namely 45-125 deg.C, to provide the objective resin. The amount of the component C preliminarily added to the reaction system is preferably >=20% based on the whole amount of the component C.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a method for producing styrenic resin.

Styrenic resins, especially low molecular weight styrene resins, are used as toners for electrophotography, bases for hot melt coating agents,
Used in pigment dispersants, resin modifiers, tackifiers, etc. It is also used as a styrene resin for molding with good fluidity.

<Conventional technology> Conventional methods for producing low molecular weight styrenic resins include:
Japanese Patent Publication No. 56-34163 discloses a method of polymerization using a large amount of a relatively low-temperature decomposable polymerization initiator. Further, JP-A-63-273606 discloses a method of solution polymerization in the presence of a solvent. Generally, methods using chain transfer agents such as mercaptans and α-methylstyrene dimer are also known.

<Problem that the invention seeks to solve> The conventional methods described above each have the following problems.

That is, the method disclosed in Japanese Patent Publication No. 56-34163 requires a large amount of polymerization initiator, which is economically disadvantageous, and also has the disadvantage that it is difficult to control the polymerization heat. Furthermore, the method disclosed in Japanese Patent Application Laid-Open No. 63-273606 requires an operation for removing the solvent, which is economically disadvantageous. Furthermore, although methods using mercaptans are generally useful, they have the problem of odor.

Furthermore, chain transfer agents having a double bond in the molecule such as α-methylstyrene dimer do not have the problem of odor, but have a problem of a smaller chain transfer constant (lower efficiency in reducing molecular weight) than mercaptans.

<Means for Solving the Problems> As a result of long-term research into the problems of the above-mentioned conventional methods, the present inventors have developed a system in which a chain transfer agent having one or more double bonds is present in the molecule. , by using a method of polymerizing while sequentially adding a styrenic monomer alone or a mixture with a vinyl monomer copolymerizable with it (hereinafter abbreviated as vinyl monomer for polymerization) and an organic peroxide. They discovered a method for efficiently lowering the molecular weight of the resulting polymer and completed the present invention.

That is, in the method of the present invention, a styrenic monomer alone or a mixture of a vinyl monomer copolymerizable with the styrenic monomer is mixed with a chain transfer agent having one or more double bonds in the molecule and an organic peroxide. When polymerizing with
In the system in which the chain transfer agent is present, at least the vinyl monomer and the 10 hour half-life temperature (290.1 mol/l on Ben)
is 0.5 to 10% organic peroxide from 35℃ to 75℃.
The present invention relates to a method for producing a styrenic resin, which comprises polymerizing the organic peroxide at a temperature 10 to 50° C. higher than the 10-hour half-life temperature of the organic peroxide while continuously or intermittently adding the organic peroxide.

Specifically, when polymerizing a vinyl monomer for polymerization, a chain transfer agent having a few (or at least one) double bond in the molecule,
Vinyl monomer for polymerization and 10 hour half-life temperature (Ben 29
A mixture of 0.1 mol 10 and an organic peroxide at a temperature of 35°C to 75°C is added continuously or intermittently over a period of 0.5 to 10 hours, and the temperature is 10 to 10% higher than the 10-hour half-life temperature of the organic peroxide.
A method for producing a styrenic resin characterized by polymerizing at a temperature 50°C higher, or by continuously or intermittently adding a mixture of the chain transfer agent, a vinyl monomer for polymerization, and an organic peroxide into a reactor. This method can be exemplified as a method for producing a low molecular weight styrenic resin, which is characterized by polymerizing the resin while polymerizing the resin.

An embodiment of the former method will be shown below.

(2) A case where a part of a mixture of the styrenic monomer to be polymerized or a vinyl monomer copolymerizable with it is mixed in advance with the chain transfer agent.

In this case, the former vinyl monomer for polymerization and the latter vinyl monomer for polymerization may have the same composition (they may also be stationery).

(2) When either a polymerization initiator or a chain transfer agent is mixed in advance with the vinyl monomer for polymerization added to the chain transfer agent.

■ A part of the chain transfer agent is added to the vinyl monomer for polymerization, and a mixture of the vinyl monomer for polymerization and a specific peroxide is added to the chain transfer agent. When a part of the mixture of the styrenic monomer to be polymerized or the vinyl monomer copolymerizable with it is mixed in advance.

Preferably, the vinyl monomer for polymerization added sequentially in steps (1) and (2) above should be at least 30% of the total monomer amount. Iichi 3
If n% is selected cheaply, the effect of molecular weight is small and the polymerization rate is high (and difficult to control).

Furthermore, the entire amount of the chain transfer agent used does not necessarily need to be present in the reaction system in advance, and a portion thereof may also be mixed with the polymerization monomer or organic peroxide that is added sequentially.

In this case, it is preferable that the amount of chain transfer agent already present in the system is usually at least 20% of the total amount of chain transfer agent used. If the amount is less than 20%, the effect of lowering the molecular weight tends to be small.

Further, in the above (2), it is preferable that the concentration of the chain transfer agent to the vinyl monomer for polymerization is the same, or that the concentration of the chain transfer agent in the mixture to be added sequentially is smaller.

The vinyl monomer for polymerization used in the present invention is styrene alone or a mixture with a vinyl monomer copolymerizable with it. Examples of the styrene monomer include styrene, α-methylstyrene, vinyltoluene, etc. be. Examples of vinyl monomers copolymerizable with styrene monomers include acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, and octyl acrylate, methyl methacrylate, ethyl methacrylate, and methacrylic acid. These include butyl, methacrylic acid esters such as octyl methacrylate, and acrylonitrile.

When the vinyl monomer for polymerization is a mixture of a styrene vinyl monomer and a vinyl monomer copolymerizable with it, the mixing ratio must be 20% or more of the styrene vinyl monomer. , preferably 50% or more.

Specifically, the chain transfer agent having at least one double bond in the molecule used in the present invention is α-methylstyrene dimer (2,4°-diphenyl-4-methyl-1-pentene) or terbinolene. , myrcene,
These include various terpenoids such as limonene, α-pinene, and β-pinene.

The chain transfer agent used in the present invention generally has a chain transfer constant of 0.4 or less with respect to the vinyl monomer for polymerization. Therefore, in the conventional polymerization method, a relatively large amount of unreacted chain transfer agent remains in the late stage of polymerization. On the other hand, in the method of sequentially adding the vinyl monomer for polymerization to the chain transfer agent of the present invention, the concentration of the chain transfer agent in the reaction system is limited, especially in the early stage of the reaction. Therefore, even a chain transfer agent with a relatively small chain transfer constant can have a large effect.

The above chain transfer agent also has the effect of reducing the polymerization rate,
As a result, the reaction can be easily controlled.

The amount of chain transfer agent used is 0.3 to 15% by weight based on the total vinyl monomers to be polymerized. If the amount is less than 0.3% by weight, the effect will be small (and if it is used in excess of 15% by weight, the commensurate effect will not be obtained and it is not economical.

The organic peroxide used in the present invention has a 10-hour half-life temperature of 35 to 75°C, and specifically, examples thereof include di-n-probilveroxyredicarbonate, diisopropylperoxydicarbonate, di(2- ethylhexyl) peroxydidicarbonate, di(3,3,5-)limethylhexanoyl)peroxydidicarbonate, di(2-ethoxyethyl)peroxydidicarbonate,
t-Butylperoxybivalate, t-butylperoxyisobutyrate, t-butylperoxyneodecanoate, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, lauroyl peroxide, 3. These include 5.5-trimethylhexanoyl peroxide, propionyl peroxide, and acetyl peroxide.

In the present invention, in order to complete the reaction in the latter half of the polymerization, a method may be used in which an organic peroxide is added and the temperature is raised as necessary.

The polymerization method used in the present invention is preferably suspension polymerization or emulsion polymerization, but bulk polymerization can also be used.

The polymerization temperature used in the present invention is 45°C to 125°C. Below 45°C, the effect of lowering the molecular weight is small;
If the temperature exceeds ℃, it becomes difficult to control the reaction.

(Effects of the Invention) The present invention, in which polymerization is carried out under specific conditions, has the following features.

That is, according to the present invention, a low molecular weight polymer can be economically produced without requiring a solvent or a large amount of polymerization initiator.

EXAMPLES The present invention will be specifically explained below using examples. In addition, the abbreviations of compounds such as polymerization initiators used in the examples mean the following compounds. In addition, the number written after the abbreviation indicates the 10-hour half-life temperature.

IPP, 40.5°C, diisopropyl peroxydicarbonate (NOF Corporation, Perloyl IPP) OPP; 43.5°C, di(2-ethylhexyl) peroxydicarbonate (NOF Corporation, Perloyl 0PP) BPV; 55°C, t-Butyl peroxyvivalate (Nippon Oil Co., Ltd., Verbutyl PV) BPO; 74°C, Benzoyl Peroxide Oil Co., Ltd., Niver B) (Japan LPO; 62°C, Lauroyl Peroxide Oil Co., Ltd., Perloil L) (Japan MSD; α -Methylstyrene Dimer, Nofumar MSD) (NOF P; Turbinolene (NOF, Nofumar TP) NDM; All molecular weights of products obtained by n-dodecyl mercaptan polymerization were determined using gel permeation chromatography (GPC). Measured in terms of polystyrene. Mn represents number average molecular weight, Mw
represents the weight average molecular weight.

The polymerization conversion rate was calculated from the amount of residual monomer determined by gas chromatography.

Example 1 A 50° vessel equipped with a reflux condenser, stirrer, thermometer, and dropping funnel
200 g of a 0.05% polyvinyl alcohol aqueous solution and MSDlog are placed in a 0 mN four-loaf flask, and the temperature is raised to 80° C. while flowing nitrogen and stirring. Next, styrene 100
g and 4 g of lPP were each added dropwise in parallel over 2 hours. Then, to complete the reaction, 2 g of BPV was added and 80
The reaction was continued for 2 hours at °C. The resulting styrene polymer was analyzed after filtering and washing the resulting burl-like polymer.

As a result, the polymerization conversion rate was 98.8%, and the number average molecular weight was 44.
00, and the weight average molecular weight was 7,900.

Example 2 Using the same reaction apparatus as in Example 1, 200 g of a 0.05% aqueous polyvinyl alcohol solution and 3 g of MSD were charged, and the temperature was raised to 80° C. while stirring with nitrogen flow.

Next, a mixture of 7 g of MSD and 100 g of styrene and lP
4 g of P was added dropwise in parallel over 2 hours. Then BPV
2g was added and the reaction was continued at 80°C for 2 hours. The resulting styrene polymer was analyzed after filtering and washing the resulting burl-like polymer. As a result, the polymerization conversion rate was 98.4%.
, number average molecular weight is 6200, weight average molecular weight is 1180
It was 0.

Comparative Example 1 Using the same reaction apparatus as in Example 1, 200 g of a 0.05% polyvinyl alcohol aqueous solution was added, and the temperature was raised to 80° C. while flowing nitrogen and stirring. Next, MSDIOg, 100g styrene and 4g IPP were added. Then at 80℃ 2
The mixture was allowed to react for an hour, then 2 g of BPV was added and the reaction was continued at 80° C. for 2 hours. The resulting pearl-like polymer was filtered and washed with water, and then analyzed.

As a result, the polymerization conversion rate was 99.2%, and the number average molecular weight was 81.
00, and the weight average molecular weight was 15,800.

As mentioned above, from the results of Example 1.2 and Comparative Example 1, by using the method of dropping styrene and IPP into the system where MSD is present, it is possible to achieve a lower molecular weight than the method of adding them all at once. can.

Comparative Example 2 The same operation as in Example 1 was performed except that MSD was not used in Example 1. As a result, the polymerization conversion rate was 99.9%.
, number average molecular weight is 13900, weight average molecular weight is 277
It was 00.

In this way, in a system that does not use MSD, styrene and IPP
It can be seen that the molecular weight cannot be lowered compared to Example 1.2 even if the method of adding dropwise is used.

Example 3 Using the same reactor as in Example 1, 200 g of a 0.05% polyvinyl alcohol aqueous solution, 30 g of styrene, α-methylstyrene log, and 7.5 g of MSD were charged, and the reactor was heated to 90° C. while flowing nitrogen and stirring. 50g of styrene and α-
A mixture of 10 g of methylstyrene and 3.5 g of BPV was added dropwise over 2 hours. Thereafter, 2 g of BP0 was added, and the reaction was continued at 90° C. for 2 hours. The resulting pearly polymer was filtered and washed with water, and the resulting styrenic polymer was analyzed. As a result, the polymerization conversion rate was 99.0%, and the number average molecular weight was 520.
0, and the weight average molecular weight was 9,800.

In this way, a part of the monomer for polymerization is placed in the system in advance,
Even if a part of MSD is used in the additive, the effect of lowering the molecular weight can be obtained.

Example 4 Using the same reactor as in Example 1, 200 g of 0.05% polyvinyl alcohol aqueous solution, 60 g of styrene, and MSDIO
g, and the temperature was raised to 70°C while flowing nitrogen and stirring. A mixture of 40 g of styrene and 3.5 g of BPO was added dropwise intermittently at 10 minute intervals over a period of 2 hours. Thereafter, 2 g of BP0 was added, and the reaction was continued at 90° C. for 2 hours. After filtering and washing the resulting burl-like polymer, the resulting styrenic polymer was analyzed.

As a result, the polymerization conversion rate was 99.8%, and the number average molecular weight was 57.
00, and the polymerization average molecular weight was 10,800.

In this way, even if a part of the monomer for polymerization is used in the system in advance, the effect of lowering the molecular weight can be obtained.

Example 5 Using the same reactor as in Example 1, 200 g of a 0.05% polyvinyl alcohol aqueous solution and TPlg were charged, and the temperature was raised to 80° C. while flowing nitrogen and stirring. A mixture of 80 g of styrene, 20 g of acrylonitrile, and 1.5 g of LP0 was added dropwise over 2 hours. After that, add 1g of BP and heat at 90℃ for 2 hours.
The reaction continued for hours. After filtering and washing the resulting burl-like polymer, the resulting styrenic polymer was analyzed. As a result, the polymerization conversion rate was 99.5%, and the number average molecular weight was 8500.
, the weight average molecular weight was 16,800.

Example 6 Using the same reactor as in Example 1, 200 g of a 0.05% polyvinyl alcohol aqueous solution and TPlog were charged, and the temperature was raised to 80° C. while flowing nitrogen and stirring. A mixture of 80 g of styrene, 20 g of butyl acrylate, and 5.5 g of OPP was added dropwise over 2 hours. After that, 2g of BPV was added and the temperature was raised to 80°C.
The reaction was continued for 2 hours. After filtering and washing the resulting burl-like polymer, the resulting styrenic polymer was analyzed.

As a result, the polymerization conversion rate was 99.6%, and the number average molecular weight was 34.
00, and the weight average molecular weight was 6,100.

In this way, even when TP is used, the effect of lowering the molecular weight can be obtained.

Example 7 Using the same reactor as Example 1, 150 g of styrene and MS
Add 40g of D, and raise the temperature to 80°C while stirring with nitrogen flow. 150 g of styrene and 5.2 g of lPP were each added dropwise in parallel over a period of 2 hours. Thereafter, the reaction was continued for 0.5 hour at 80°C. The produced styrene polymer was analyzed. As a result, the polymerization conversion rate was 68.2%, the number average molecular weight was 9500,
The weight average molecular weight was 19,000.

In this way, even when bulk polymerization is used in the present invention, the effect of lowering the molecular weight can be obtained.

Comparative Example 3 The same operation as in Example 1 was performed except that MSD was not used in Example 7. As a result, during the dropwise addition of styrene and IPP, stirring became impossible and the temperature rose due to heat generation, making it impossible to control the temperature.

As described above, bulk polymerization without using MSD not only does not have the effect of lowering the molecular weight, but also increases the polymerization rate and makes it impossible to control the reaction.

Example 8 Using the same reactor as Example 1, 150 g of styrene and TP
Add 40g of the mixture, and heat it to 90°C while stirring with nitrogen flow. A mixture of 150g of styrene and 4.2g of BPO
It dripped in time. Thereafter, the reaction was continued for 0.5 hour at 90°C. The produced styrene polymer was analyzed. As a result, the polymerization conversion rate was 63.5%, the number average molecular weight was 9,200, and the weight average molecular weight was 18,500.

Comparative Example 4 Styrene log and TP in a glass ampoule with a capacity of 20 mj
3 g of BPOl and 4 g of BPOl were put therein, and the tube was replaced with nitrogen, followed by melt-sealing. It was polymerized in a constant temperature oil bath at 90°C for 4.5 hours. As a result of analyzing the polymer, the polymerization conversion rate was 95.5%,
Number average molecular weight is 27500, weight average molecular weight is 5180
It was 0.

From Example 8 and Comparative Example 4, the effect of lowering the molecular weight is small in bulk polymerization without dropping styrene and TP.

Claims (1)

[Claims] When polymerizing a styrenic monomer alone or a mixture of a vinyl monomer copolymerizable with it using a chain transfer agent having one or more double bonds in the molecule and an organic peroxide,
In the system in which the chain transfer agent is present, at least the vinyl monomer and the 10 hour half-life temperature (0.1 mol/l in benzene)
is 0.5 to 10% organic peroxide from 35℃ to 75℃.
A method for producing a styrenic resin, which comprises polymerizing the organic peroxide at a temperature 10 to 50° C. higher than the 10-hour half-life temperature of the organic peroxide while continuously or intermittently adding the organic peroxide.