JPS62197406A - Production of low-molecular weight copolymer of styrene with maleic anhydride - Google Patents

Abstract

PURPOSE:To obtain the title copolymer soluble in an alkaline aqueous medium, by specifying a solvent, a polymerization temperature,an initiator concentration, a monomer feed rate, etc. in copolymerizing styrene with maleic anhydride by feeding them to the polymerization reaction system. CONSTITUTION:Styrene is mixed with maleic anhydride at a molar ratio of 2.5:1-5:1, and the obtained monomer mixture is slowly fed to the polymerization reaction system at a rate not exceeding the rate of polymerization to produce a copolymer. At this time, 0.3-2pts.wt., per pt.wt. total monomer, high-boiling aromatic hydrocarbon is used as a solvent, the polymerization temperature T is controlled at 140-190 deg.C, the initiator concentration C per 100g of the monomer is adjusted to 0.001-0.03mol, and the monomer feed rate is adjusted to 8-40wt%/hr, and the copolymerization reaction is performed under the polymerization conditions shown in the table. In this way, a low-MW styrene/ maleic anhydride copolymer soluble in an alkaline aqueous medium can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a low molecular weight styrene-maleic anhydride copolymer. Specifically, the present invention has a high styrene content in the copolymer composition,
The present invention also relates to a method for producing a low molecular weight styrene-maleic anhydride copolymer having a uniform composition.

(Prior Art) Low molecular weight copolymers of styrene and maleic anhydride have a wide range of applications in surface coating formulations, either alone or in combination with other materials such as synthetic resins. Applications vary depending on whether this low molecular weight copolymer is used as an alkaline aqueous solution or dissolved in an organic solvent, but examples include paints, adhesives, synthetic resins, fiber treatment agents, and fiber modifiers. Furthermore, it can be expected to be applied as a plasticizer, dispersant, emulsion stabilizer, crosslinking agent, etc. In addition, one of the properties of this material is that it has a low degree of polymerization, which makes it easy to handle, and it is also of particular industrial interest because it can be easily cured or bonded by secondary crosslinking through simple processing. I can lean back.

By the way, when a general copolymerization is carried out by heating styrene and maleic anhydride to an appropriate temperature in a large reactor using a catalyst, once the polymerization reaction starts, it is impossible to control the polymerization reaction. , the resulting copolymer has a high molecular weight,
In addition, styrene and maleic anhydride have a strong tendency to heteropolymerize, making it impossible to obtain a copolymer with a molar ratio of styrene and maleic anhydride other than 1:1. Ta.

Therefore, when trying to obtain the above-mentioned low molecular weight copolymer, the polymerization reaction must be delayed in the presence of a substance that inhibits polymerization, such as a quinone derivative such as ditarjalibdelquinone. Methods for reducing the degree of polymerization include U.S. Time i' (No. 2, No. 640.819) and methods for expecting a decrease in the degree of polymerization by adding specific molecular weight regulators such as terpinolene (Japanese Patent Publication No. 39-17). , No. 066)
etc. were taken.

However, in the former case, it is necessary to control the molecular weight sufficiently low and to keep the composition ratio of styrene and maleic anhydride to 1.
:It is not expected to obtain a low molecular weight copolymer of 1 or more,
In the latter case, the product becomes a so-called binary copolymer in which the added substance is added to the end of the resulting polymer chain, or a mixture of copolymers in which the added substance is copolymerized with styrene or maleic anhydride. It is not possible to completely copolymerize only two components while controlling the degree of polymerization. Moreover, conventional methods including these examples,
Most of these methods are based on a bulk polymerization method, and molecular weight control often tends to be difficult due to the self-reaction promoting effect due to heat generation during the reaction.

On the other hand, as a method for effectively producing a low molecular weight copolymer consisting of only two components, a solution polymerization method is more practical. For example, when styrene and maleic anhydride are solution polymerized, Chain transfer to polymerization system?
A method for producing a low molecular weight copolymer of styrene and maleic anhydride by adding dialkylaniline as 411 to cause degenerative chain transfer (Japanese Patent Publication No. 48-43).
664@), etc. However, such a method is not preferred from an industrial point of view because the polymerization yield is saturated by 70 to 80% of the former compound.

A small amount of ffi in the styrene-maleic anhydride copolymer
, Q When producing a copolymer in which maleic anhydride is uniformly dispersed by solution polymerization or bulk polymerization, the consumption rate of maleic anhydride is much higher than that of styrene. A method of continuously adding maleic anhydride to the reaction system of styrene (U.S. Patent No. 2,
No. 971,939) is also known. However, with this method, it is not possible to obtain a copolymer with a uniform composition, and only a copolymer that is insoluble in an aqueous alkaline medium can be obtained.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide a method for producing a novel low molecular weight styrene-maleic anhydride copolymer. Another object of the present invention is to provide a method for producing a styrene-maleic anhydride copolymer in which a small amount of maleic anhydride is uniformly distributed in the styrene-maleic anhydride copolymer. The present invention further provides that the molar ratio of styrene and maleic anhydride in the obtained copolymer is 2.
The object of the present invention is to provide a method for producing a low molecular weight styrene-maleic anhydride copolymer in which the ratio is 5:1 to 5:1 and the copolymer is completely soluble in an aqueous alkaline medium. .

(Means for solving the problem) Although the composition of the styrene-maleic anhydride copolymer is rich in styrene, in order for the copolymer to be completely dissolved in an aqueous alkaline medium, it is necessary to The composition ratio must be uniformly distributed.

However, as mentioned above, in the copolymerization reaction of styrene and maleic anhydride, the molar ratio in the copolymer is 1:1.
A so-called alternating copolymer in which the respective monomers are bonded alternately is likely to be produced, and therefore it is not easy to obtain a random copolymer with a small amount of maleic anhydride.

In order to obtain a low molecular weight random copolymer in which a small amount of maleic anhydride is uniformly distributed in the desired copolymer,
It is important to control the reaction system so that a small amount of unreacted maleic anhydride is always present in the polymerization system throughout the entire polymerization reaction time. From this perspective, the present inventors
As a result of intensive research, we found that when attempting to form a copolymer by sequentially adding a mixture of styrene and maleic anhydride to a polymerization reaction system, if the polymerization is carried out under certain limited conditions, The inventors have discovered that the object can be achieved and have arrived at the present invention.

That is, the present invention provides a method for producing a copolymer by sequentially adding a monomer mixture of styrene and maleic anhydride to a polymerization reaction system at a rate not exceeding the polymerization rate. Using a high-boiling aromatic hydrocarbon with a temperature corresponding to
, monomer] at a polymerization initiator concentration C of 0.001 to 0.03 mol per OOg and a monomer addition rate θ of 8 to 40 wt%/hour, and (a) when 22≦θ≦40, C≧−4,2X10 -4T±0.076C≦-4,3x
10-4T+0.099 (b) When 13≦θ<22 C≧-9, 9x104T+0.155 0≦-5, 0x10°4T+0.110-4T+0.1
10(c) When 8≦θ<13, C≧−11,0X10−
4T+0.174C≦-5,6X10-4T+0.11
The molar ratio of styrene and maleic anhydride is 2.5:1 to 5.
:1 and is a method for producing a low molecular weight styrene-maleic anhydride copolymer which is soluble in an aqueous alkaline medium.

The present invention will be described in more detail below based on embodiments.

The present invention provides reproducible low molecular weight styrene-Maleic anhydride copolymers in which the molar ratio of styrene to maleic anhydride in the copolymer is 2.5:1 to 5:1 and is soluble in aqueous alkaline media. This method is commonly used to produce copolymerization using the gradual internal addition technique, i.e., the highly reactive monomer styrene and maleic anhydride mixture are sequentially added to the polymerization reaction system at a rate that does not exceed the polymerization rate. It applies the technology for manufacturing coalescence under certain conditions.

The monomers used in the production method of the present invention are styrene and maleic anhydride. These are mixed in advance under non-polymerization reaction conditions, for example at a temperature of 30 to 50°C, and then added to the polymerization reaction system.

For example, styrene and maleic anhydride are dissolved and mixed in a portion of the solvent used. The molar ratio of styrene and maleic anhydride in this monomer mixture is approximately 2.5:1 to 5:1 depending on the copolymer composition to be obtained.

As a solvent, a high 911 point aromatic hydrocarbon which is inert to the monomer and the resulting copolymer and has a large chain transfer effect is used. , Shimen et al.

These solvents are used in an amount corresponding to 0.3 to 2 times the total weight of the solvent.

The polymerization initiator is used in an amount of 0.001 to 0.00% per 100Q of monomers.
0.03 mol, more preferably 0.0015 to 0.015 mol. That is, when the polymerization initiator concentration C is 0.00
If it is less than 1 mole, the polymerization rate will not increase even if the polymerization is carried out for a long time, while if it is more than 0.03 mole, the polymerization will be too rapid and a uniform composition may not be obtained, and the production cost will be too high, which is undesirable. . As the polymerization initiator, those that can be used at relatively high temperatures are used, such as t-butylcumyl peroxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, p-
Menthane hydroperoxide, cumene hydroperoxide, methyl isobutyl ketone hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di([-
Peroxides such as butyl peroxide) hexane, benzoyl peroxide, acetyl peroxide, 1°1°
Azo compounds such as -azobis(cyclohexane-1-carbonitrile) and azobisisobutyronitrile may be used.

These polymerization initiators are added to the polymerization reaction system simultaneously with the monomers. Therefore, the polymerization uD initiator can be added to the polymerization reaction system after being dissolved in a solvent in which the monomer mixture as described above is dissolved, or the polymerization initiator can be added to a solvent part other than the solvent in which the monomer mixture is dissolved. Dissolve and
It is also possible to add it to the polymerization reaction system simultaneously with the monomer mixture.

Thus, the monomer mixture and polymerization initiator, as described above, are added sequentially to the polymerization reaction system, eg, the reaction vessel containing the remainder of the solvent described above. The temperature of the polymerization reaction system is 140 to 190°C, more preferably 150 to 180°C.
The polymerization temperature T is maintained at °C. Polymerization temperature T from 140 to
The reason why the temperature is 190°C is because at a temperature lower than 140°C, styrene and maleic anhydride tend to bond alternately.
This is because if the temperature is higher than 90°C, there is a possibility that a part of the produced copolymer will start to decompose during polymerization.

The monomer addition rate θ to such a polymerization reaction system is 8
~40% by weight/hour, more preferably 11-33% by weight
/It is time. In other words, if the monomer addition rate θ is outside this range, under the above-mentioned preferred polymerization initiator concentration C and polymerization temperature conditions, it is difficult to reproducibly dissolve a copolymer with a uniform composition, which is completely transparently dissolved in an aqueous alkaline medium. You can't get much.

Furthermore, in the production method of the present invention, the monomer addition rate θ, the polymerization initiator concentration C, and the polymerization temperature T need to be controlled so as to satisfy the following condition A'1.

That is, (a) When 22≦0≦40 (7), C≧−4, 2×104T+0.076 G≦−4, 3×10−4T+0.09 9 (b) When 13≦θ<22, C≧− 9,910-4-r10.155C≦-5,0x
10-4T+0.110-4T+0.110(c)8≦
When θ<13, C≧-11, 0XIO-4T+0.17
Adjust so that 4C≦-5,6X"lo-4T~←0.1]9 (see Fig. 1).

That is, if the conditions are outside this range, there is a risk that the desired copolymer may not be obtained even if the monomer addition rate θ, polymerization initiator concentration C, and polymerization temperature T are within the above-mentioned preferred ranges. This is because it has become clear that

-C can be obtained by sequentially adding the monomer mixture to the polymerization reaction system under the above-determined conditions, but if necessary, 0.0% per 100 g of monomer may be added to the polymerization reaction system as a chain transfer agent. It is also possible to add 0.03 to 0.04 moles of mercaptans such as n-octyl mercaptan, n-hexyl mercaptan, etc. By adding mercaptans, the degree of polymerization of the resulting styrene-maleic anhydride can be sufficiently lowered. Furthermore, if necessary, add 100 CI of monomer to the polymerization reaction system.
It is also possible to add 0.003 to 0.04 mol per terpinolene. Terpinolene is generally added for the purpose of lowering the degree of polymerization, but in the production method of the present invention, terpinolene is not used as a polymerization degree regulator, but rather subtly suppresses the polymerization reaction rate, allowing styrene and maleic anhydride to is added to allow the intense polymerization reaction to occur in a more steady state. These mercaptans and terpyrunes are added sequentially to the polymerization reaction system depending on the monomer addition rate.

In the production method of the present invention, the polymerization reaction proceeds extremely quickly by adding the monomer mixture to the polymerization reaction system, but since the monomers are added sequentially, only a small amount of monomer is always present in the polymerization reaction system. However, the concentration of polymerization initiator is higher and the polymerization reaction temperature is higher than that of conventional methods.
There is no problem of explosive reaction, the operation is extremely safe, and the yield is extremely high at 95-100%. After the polymerization reaction is completed, the solvent and unreacted monomers can be removed under reduced pressure, and solvents such as ethylbenzene, cymene, and cumene can be removed from styrene at low temperatures.
Since it has low solubility in maleic anhydride, the reaction system can be cooled after the polymerization reaction is completed to precipitate the produced copolymer and separate it from the solvent and unreacted monomer. However, compared to the separation and purification method using precipitation, the reduced pressure removal method is much easier to operate and is industrially advantageous. As briefly mentioned above, the fact that the yield of the present invention is close to 100% by weight makes purification easier.

As the reaction vessel used in the polymerization reaction system in the production method of the present invention, a normal pressure type reaction vessel is usually used, but a pressurized type polymerization vessel may also be used. The pressure at this time varies depending on the solvent used, but it is 1.5 to 3
kg/cri, more preferably 2 to 3 kg/cd.

The copolymer of styrene and maleic anhydride obtained by the production method of the present invention has a molar ratio of styrene and maleic anhydride in the copolymer of 2.5:1 to 5:1, more preferably 3:1. ~4.5:1, resulting in a uniform composition. If this molar ratio is less than 2.5:1, the properties of styrene will be diminished, while if it exceeds 5:1, it will be difficult to obtain a copolymer that completely dissolves in an aqueous alkaline solvent, and both are impractical. Limited. The average molecular weight of this copolymer of styrene and maleic anhydride is 2000 to 90.
00, and the ammonia water dissolution viscosity (30'C) is 4~
1000CE)S, making it extremely easy to handle.

(Example) The present invention will be described in more detail below based on Examples.

The acid value, haze value and viscosity of an alkaline aqueous solution of the copolymer in the cl'3 Examples and Comparative Examples were measured by the following methods.

Acid value 200ml triangular flask with a stopper] and a convergence sample of about 0.5
9 was accurately weighed, about 50 d of methylene chloride was added thereto, dissolved, and left to stand for about 30 minutes. After titration with N/10-sodium methylate methanol solution using 0.5% thymol blue methanol solution as an indicator, the color changed from yellow to blue. The end point is the point at which the value of the copolymer becomes 1), and the acid value of the copolymer is calculated linearly using the following formula. All tests will be conducted separately.

Acid value = fx (Δ-3) Consumption M (d), B: Consumption amount of N/10-sodium methylate methanol solution during blank test (d), S: Sample weight (q) Haze value of alkaline solution Copolymer sample in test tube Weigh out 30 ml of water, add 30 d of distilled water and 6 tbsp of 25-28% ammonia water, and make about 80 ml of water.
After dissolving the sample by heating to
).

However, in the formula, 1-1: Haze (%), T-d: Diffuse transmittance (%), Tt: Total light transmittance (%). Prepare a 15% solution of the copolymer by adding 15% excess of the required amount of 25-28% ammonia water calculated from the value, and measure the dissolution of the copolymer in ammonia water using a B-type viscometer. Viscosity (30℃>
(cps).

Examples 1 to 8 and Reference Examples 1 to 2 Anhydrous maleic M123Cl to cumene 150C1
The mixture was dissolved at 50° C., and styrene 520Q, terpinolene 10.30, and dicumyl peroxide of the type shown in Table 1 were added to prepare a solution. Further, this was added to 150 g of n-octyl mercaptanmen to prepare solution B.

182 g of cumene was placed in a 2Q volume atmospheric pressure reaction vessel equipped with a reflux condenser, a thermometer and a stirrer, and placed in an oil bath maintained at 165°C.The reaction vessel was prepared as shown in Table 1. The A solution and the B solution prepared above were continuously added dropwise to the reaction vessel over the time shown in Table 1 while maintaining the polymerization temperature. After 30 minutes had passed after the completion of the dropwise addition, heating was stopped to complete the polymerization reaction. The yield and analytical data of the obtained copolymer are shown in Table 2.

Examples 9 to 13 and Reference Example 3 Anhydrous maleic M123Cl was added to 150 g of p-cymene at 40 g.
The mixture was dissolved at ~50°C, and a solution was prepared by adding styrene 520Q, terpinolene 10.3 Cl, and dicumyl peroxide in the amount shown in Table 3. Further, this solution was added to 5.79Q of n-octylmercaptan@150g of p-cymene to prepare solution B.

Put p-cymene 1B2CI'4i into a 29-volume normal-pressure reaction vessel equipped with a centrifugal cooling PJl vessel, a thermometer, and a stirrer,
Place this in an oil bath kept at a temperature of 185°C, and
While maintaining the polymerization temperature shown in the table, the Δ solution and the B solution were continuously dropped into the reaction vessel over the time shown in Table 3. After 30 minutes had elapsed since the dropwise addition was completed, heating was stopped to complete the polymerization reaction. The yield and analytical data of the obtained copolymer are shown in Table 4. Examples 14 to 6 and Reference Example 4 Solution A was mixed with 98.4Q of maleic anhydride and 416g of styrene.
, terpinolene 8.24Q, prepared with dicumyl peroxide in the amounts shown in Table 3 and 120 Cl of p-cymene-1, while solution B was prepared with ≠ 4.63C of mercaptan and 20 g of p-cymene-1 Polymerization was carried out in the same manner as in Examples 9 to 13, except that 145.8Q of p-cymene was placed in the reaction vessel. The yield and analytical data of the obtained copolymer are shown in Table 4.

Examples 17-18 and Reference Examples 5-8 Examples 1-8 except that the temperature of the oil bath was set at 145°C
Polymerization was carried out in the same manner. The polymerization conditions are shown in Table 5, and the yield and analytical data of the obtained copolymer are shown in Table 6.

(Left below) (Effects of the Invention) As described above, the present invention provides a method for producing a copolymer by sequentially adding a monomer mixture of styrene and maleic anhydride to a polymerization reaction system at a rate not exceeding the polymerization rate. The highest boiling point aromatic hydrocarbon corresponding to 0.3 to 2 times the weight of the monomer is used as the solvent, and the temperature is 140 to 190°C.
at a polymerization temperature of 0.001 to 0.00% per 100 g of monomer.
(a) When 22≦θ≦40, C≧−4,2×104T+0.076 0≦−4,3×10′ 100.099 (b) When 13≦θ<22 C≧-9, 9x104T+0.155 C≦-5, OX 10' T+0.110-4T+0.
110(c) When 8≦θ<13, C≧-11, 0x10
-4T+0.174C≦-5,6x104T+0.11
9 The molarization of styrene and maleic anhydride is carried out under polymerization conditions of 2°5:1 to 5:
1 and is a method for producing a low molecular weight styrene-maleic anhydride copolymer that is soluble in an aqueous alkaline medium, so it can produce a styrene-maleic anhydride copolymer with a uniform composition and an excess of styrene, which has been difficult to obtain until now. The copolymer obtained by the production method of the present invention has a low molecular weight and is soluble in aqueous alkaline media, so it is easy to handle and can be applied in a wide range of fields. becomes.

[Brief explanation of drawings]

FIG. 1 is a graph showing the range of polymerization conditions in the production method of the present invention.

Claims (4)

[Claims] (1) In a method of producing a copolymer by sequentially adding a monomer mixture of styrene and maleic anhydride to a polymerization reaction system at a rate not exceeding the polymerization rate, the amount as a solvent is equivalent to 0.3 to 2 times the weight of the total monomers. using an amount of high-boiling aromatic hydrocarbon, polymerization temperature T of 140 to 190°C, monomer 1
With a polymerization initiator concentration C of 0.001 to 0.03 mol per 00 g and a monomer addition rate θ of 8 to 40 wt%/hour, and (a) 22≦θ≦40, C≧−4.2×10＾ -^4T+0.076C≦-4.
3×10^-^4T+0.099(b)13≦θ<22
In the case of C≧-9.9×10^-^4T+0.155C≦-5.
0×10^-^4T+0.110 (c) When 8≦θ<13 C≧-11.0×10^-^4T+0.174C≦-5
．． The polymerization is carried out under polymerization conditions of 6×10^-^4T+0.119, and the molar ratio of styrene and maleic anhydride is 2.5:1 to 5:1, and the low molecular weight is soluble in an aqueous alkaline medium. A method for producing a styrene-maleic anhydride copolymer. (2) The manufacturing method according to claim 1, wherein ethylbenzene, cumene, cymene, or a mixture thereof is used as the solvent. (3) 0.003 to 100 g of monomer in the polymerization reaction system
The manufacturing method according to claim 1 or 2, wherein 0.04 mol of mercaptans is added. (4) 0.003 to 100 g of monomer in the polymerization reaction system
The manufacturing method according to claim 1 or 3, wherein 0.04 mol of terpinolene is added.