KR101208903B1 - Dispersion agent for suspension polymerization and preparing method thereof and method for suspension polymerization using the same - Google Patents

Abstract

(상기 식에서, R¹은 H 또는 CH₃을, M¹은 리튬, 나트륨, 칼륨, 암모늄염에서 선택되는 어느 하나이다.)
[화학식 2]

(상기 식에서, R²는 H 또는 CH₃을, M²는 리튬, 나트륨, 칼륨, 암모늄염에서 선택되는 어느 하나이다.)The present invention relates to a copolymer for suspension dispersant of suspension polymerization having excellent polymerization stability and a suspension polymerization method of a vinyl-based resin using the same, including 10 to 85 wt% of the monomer of Formula 1, 5 to 45 wt% of the monomer of Formula 2, and ( It is a copolymer obtained by homogeneously polymerizing a monomer mixture composed of meta-acrylic acid ester monomers in an aqueous solution of 10 to 45 wt%. Provided are a dispersant for coalescence and a method for preparing the same.
[Formula 1]

(Wherein R ¹ is H or CH ₃ and M ¹ is any one selected from lithium, sodium, potassium and ammonium salts.)
(2)

(Wherein, R ² is H or CH ₃ , M ² is any one selected from lithium, sodium, potassium, ammonium salt.)

Description

Dispersion agent for suspension polymerization, preparation method thereof, and suspension polymerization method using the same {Dispersion agent for suspension polymerization and preparing method about and method for suspension polymerization using the same}

The present invention relates to a dispersant for suspension polymerization of vinyl monomers, in particular (methyl) methacrylic acid ester, a method for preparing the same, and a suspension polymerization method of a vinyl monomer using the dispersant.

Conventionally, many proposals have been made regarding a method of suspension polymerization of vinyl monomers such as acrylic esters and methacrylic esters. In particular, in suspension polymerization, many substances have been proposed as a dispersant to maintain the monomer droplets dispersed in water and to keep them agglomerated even during the reaction.

Typical dispersants include poorly soluble inorganic compounds such as calcium phosphate, aluminum hydroxide, silica, nonionic polymer compounds such as polyvinyl alcohol, cellulose, polyacrylic acid and the like Salts, polymethacrylic acid and salts thereof, anionic polymer compounds such as methacrylic acid esters and methacrylic acid and salts thereof, and the like are well known.

When the inorganic dispersant is used in the suspension polymerization of the acrylic polymer requiring transparency, a large amount of the dispersant is required and is not easily removed by washing after polymerization.

On the other hand, in the case of a dispersant made of polyvinyl alcohol or a cellulose derivative, the dispersant is present at the resin interface and remains without being washed off at all, thereby reducing the optical properties of the resin. Accordingly, Japanese Patent Application Publication No. 1994-80709 proposed a modified polyvinyl alcohol dispersant containing an α-olefin unit, but focused on increasing the plasticizer absorption rate by making porous particles.

In general, there are many proposals for a dispersant composed of (meth) acrylic acid esters and salts thereof, which are anionic polymer compounds, but they have polymerization stability but relatively large amounts should be used, or they are degraded during processing after polymerization due to poor thermal stability of the dispersant. In some cases, large amounts of scale were generated in the reactor during polymerization, resulting in economic losses in terms of time and quality control. In addition, since the hydrophilic functional group is a carboxyl group, the stability of the polymerization is greatly influenced by the amount of the buffer salt or the ratio of the buffer salt, which is added to adjust the pH during the reaction, thus causing difficulties in quality control.

In order to solve this problem, Japanese Patent Laid-Open Nos. 1989-168702 and 2004-168937 used a dispersant having a hydrophilic sulfonic acid group having a low pH effect on the side chain, and solved the problems due to the influence of optical properties and pH. However, the (meth) acrylic acid derivatives containing sulfonates are formed with peroxides over time, and due to the peroxide impurities contained in the (meth) acrylic acid derivatives with sulfonates, scale generation during suspension polymerization and the shape of the polymerized particles In the polymerization stability such as the like, good results cannot be obtained, and it is difficult to show a sufficient effect on the stability of the suspension polymerization.

In Korea Patent No. 0674373, styrene sulfonic acid group was introduced into the dispersant to improve the polymerization stability, but styrene sulfonic acid group is a dispersant suitable for methacryl resin having N-substituted maleimide as a copolymer component and thus suspension polymerization of general vinyl monomers. In order to use it, there is a disadvantage that two kinds of dispersant must be mixed.

Therefore, there are many problems to be solved to make dispersant having low polymerization stability, uniform particle shape and scale and fine powder without deteriorating optical properties.

The present invention is to solve the problems of the prior art as described above, a small scale generation and uniform particle shape during suspension polymerization of the vinyl-based monomer, and the fine powder has a specific structure so that the yield and post-processability can be improved It is an object of the present invention to provide a dispersing agent for suspension polymerization having a good polymerization stability with good affinity with vinyl monomers and hydrophilicity and hydrophobicity of the copolymer itself, and a method of manufacturing the same.

Still another object of the present invention is to provide a suspension polymerization method using the dispersant and a polymer having excellent optical properties using the same.

The present invention has been made in order to achieve the above object, the copolymer of the present invention is a monomer having a hydrophilic sulfone group represented by the following formula (1) 10 ~ 85 wt%, two or more (meth) acrylic acid derivatives represented by the following formula (2) The monomer mixture consisting of 5 to 45 wt% and 10 to 45 wt% of the (meth) acrylic acid monomer is polymerized in an aqueous solution.

[Formula 1]

(Wherein R ¹ is H or CH ₃ and M ¹ is any one selected from lithium, sodium, potassium and ammonium salts.)

[Formula 2]

(Wherein, R ² is H or CH ₃ , M ² is any one selected from lithium, sodium, potassium, ammonium salt.)

Hereinafter will be described in detail with respect to the configuration of the present invention.

At this time, if there is no other definition in the technical terms used in the present invention, it has a meaning commonly understood by those skilled in the art to which the present invention belongs, and in the following description unnecessarily obscure the subject matter of the present invention. Description of known functions and configurations that may be omitted.

The present invention relates to a multi-component copolymer consisting of 10 to 85 wt% of the monomer of Formula 1, 5 to 45 wt% of the monomer of Formula 2 and 10 to 45 wt% of the (meth) acrylic acid monomer. It is characterized in that it is used as a dispersant during suspension polymerization of vinyl monomers.

The monomer represented by the formula (1) has a sulfonate in the side chain, the kind of possible salts such as lithium (Lithium), sodium (Natrium), potassium (Kalium) or ammonium (ammonium) salt and the like can be used. By introducing sulfonate into the side chain, it is possible not to be greatly influenced by the pH of the polymerization solution during the reaction. In addition, since the chemical structure between the double bond and the sulfonate is a hydrocarbon instead of an ester, there is no need to worry about deterioration of dispersant performance due to peroxide generation over time.

The monomer represented by the formula (2) is a (meth) acrylic acid ester salt, and the kind of salt may be lithium, sodium, potassium or ammonium salt, and the like, preferably sodium or potassium.

The (meth) acrylic acid ester monomer includes any monomer selected from methyl acrylate, ethyl acrylate, methyl methacrylate or ethyl methacrylate.

In the present invention, the dispersant of the multi-copolymer should maintain a ratio of 10 to 85 wt% of the monomer of Formula 1 and 5 to 45 wt% of the monomer of Formula 2. If the proportion of the monomer of Formula 1 is less than 10 wt%, the resulting hydrophilicity of the copolymer is insufficient, resulting in a decrease in polymerization stability, resulting in the formation of large particles and irregular shape of the particles, and in some cases, the reaction may be solidified. . In addition, if the content exceeds 85 wt%, the hydrophilicity of the copolymer becomes too high, and the product particle distribution is widened when it is used for suspension polymerization, and a large amount of fine powder is generated, which impedes economic problems due to reduced suspension polymerization yield and post-treatment such as wastewater. Problems may arise.

The monomer of Chemical Formula 2 serves to improve the polymerization stability of the (meth) acrylic acid ester monomer, in particular among the vinyl monomers used in suspension polymerization, in particular R ² CH ₃ , M ² Sodium or potassium It is preferable. If the total amount is less than 5 wt%, the polymerization stability such as scale generation and particle aggregation becomes worse, and if it exceeds 45 wt%, the pH dependency becomes high.

The (meth) acrylic acid ester monomer is hydrophilic while the other monomers exhibit a lipophilic component and thus serve as a ring of a dispersant for oil phase droplets dispersed in an aqueous phase. Therefore, when the content of the (meth) acrylic acid ester monomer is less than 10% by weight, the hydrophilicity of the copolymer is insufficient and does not substantially function as a dispersant. When the content of the (meth) acrylic acid ester monomer is higher than 45% by weight, the polymerization stability becomes very low and the polymerization becomes unstable.

The polymerization method of the copolymer which is a dispersing agent of this invention is demonstrated.

The copolymer as a dispersant according to the present invention is prepared by homogeneous solution polymerization in an aqueous solution because all of the monomers of Formula 1 and Formula 2 are dissolved in water and the copolymer is used as a dispersant for aqueous suspension polymerization.

The copolymer is characterized in that the monomer and the initiator of the following formula (1) and (2) are added to the aqueous solution, and then all or part of the (meth) acrylic acid monomer is continuously or partially added.

The polymerization initiator for obtaining the polymer is sufficient as long as it is an initiator that can be used for polymerization of the water-soluble vinyl compound, and the like. Such water-soluble polymerization initiators include water-soluble inorganic compounds such as persulfate or redox-based polymerization initiators, 2,2'-azobis (2-amidinopropane) dihydrochloride (2,2'-Azobis (2- Aqueous nitrogen compounds, such as amidinopropane) dihydrochloride), etc. are mentioned. It is preferable to use 0.01-3 mass parts of content of the said polymerization initiator with respect to 100 mass parts of whole monomer mixtures.

The polymerization reaction temperature can be arbitrarily determined within 25 to 150 ° C., and polymerization at room temperature or below is particularly preferred using a redox initiator.

In addition, in order to prepare a three-way copolymer using a (meth) acrylic acid ester monomer in an aqueous solution, in consideration of the reactivity and solubility of the monomer, the content of the (meth) acrylic acid ester monomer in the aqueous phase must be maintained to be 1.5% or less. All or part of the monomer content is continuously added dropwise or time-divided into a predetermined amount and reacted. When the content of the (methyl) methacrylic ester monomer dissolved in the aqueous solution is 1.5% or more, a (meth) acrylic acid ester homopolymer, not a copolymer, is produced due to the difference in polymerization reactivity.

In using the polymer of this invention as a dispersing agent of suspension polymerization, the monomer of following General formula (3) can be further included as needed.

(3)

(Wherein R ³ is H or CH ₃ , M ³ is lithium, sodium, potassium, ammonium salt, n is an integer of 0 to 3)

The multi-part copolymer further comprising the monomer of Formula 3 may include 3 to 80 wt% of monomer of Formula 1, 0.5 to 60 wt% of monomer of Formula 3, 5 to 45 wt% of monomer of Formula 2, and 10 to (meth) acrylic acid monomer. The monomer mixture consisting of 45 wt% is characterized by polymerization in a homogeneous aqueous solution.

In this case, the total of the monomer is preferably 3 to 50wt% with respect to water so that the total polymerization of the monomers can be dispersed in a uniform phase.

Hereinafter, the suspension polymerization method of the vinyl monomer using the dispersing agent of this invention is demonstrated.

In the present invention, the suspension polymerization is used 0.005 ~ 1 parts by weight of the dispersant according to the present invention with respect to 100 parts by weight of the vinyl monomer, 0.01 ~ 2 parts by weight of an electrolyte having a monovalent to trivalent cation to improve the polymerization efficiency. It is desirable to. If the amount of the dispersing agent is less than 0.005 parts by weight, the polymerization stability is lowered, resulting in uneven particles or the reaction is solidified. If the amount is more than 1 part by weight, the particles become too fine, resulting in a lot of loss during the washing and drying process. This occurs a lot of difficulties in the wastewater treatment, there is a disadvantage that it is easy to cause fish eye (fish eye) and the extrusion process is not good.

The vinyl monomers used for the suspension polymerization are sufficient as long as they can be radically polymerized in the water phase, and are not limited thereto. The vinyl monomers include methacrylic acid esters including methyl methacrylate, ethyl methacrylate, butyl methacrylate and t-butyl methacrylate; Acrylic esters including methyl acrylate, ethyl acrylate and isobutyl acrylate; Aromatic vinyl compounds including styrene and α-methylstyrene; Or N-substituted maleimide, including N-cyclohexyl maleimide and N-phenylmaleimide.

The vinyl monomer is characterized in that the content of the methacrylic acid ester is at least 50% by weight in order to maximize the effect of the copolymer.

There is no restriction | limiting in particular about the polymerization initiator used for suspension polymerization which used the polymer of this invention as a dispersing agent, The polymerization initiator of each kind known conventionally can be used for superposition | polymerization of a vinylic monomer can be used. Specific examples include azo initiators such as 2,2'-azobis isobutyronitrile, benzoyl peroxide, t-butyl peroxy-2-ethylhexa Organic peroxide type polymerization initiators, such as noate (t-butyl peroxy-2-ethylhexanoate), etc. are mentioned.

The cationic electrolyte may help reduce emulsified particles because it makes it difficult for the vinyl monomer to be present alone in addition to the monomer droplets. Examples of the cationic electrolytes include alkali metal cations such as lithium, sodium and potassium, and hydrochlorides, sulfates, and phosphates of ammonium cations.

In the suspension polymerization according to the present invention, the mass ratio of monomer and water is preferably 1/1 to 1/10, more preferably 1 / 1.1 to 1/5. If it is out of the above range, there is a risk that the reaction will solidify or the economy will be low.

In the suspension polymerization method using the dispersant of the present invention, known additives such as a mold release agent, an ultraviolet absorber, a pigment, and a crosslinking agent which are generally used may be further included.

As described above, in the case of the suspension polymerization using the dispersing agent of the multi-copolymer according to the present invention, excellent polymerization stability and uniform particle shape can produce polymerized particles having low fine powder and scale generation, and preparing such polymers. It is possible to provide a copolymer for dispersing agent to.

The present invention will be described in more detail with reference to the following examples and comparative examples.

However, the Examples are provided to illustrate the present invention and the present invention is not limited thereto. In addition, in the Example and the comparative example, physical property evaluation was performed by the method shown below.

[Measurement and Evaluation of Properties]

1) Scale observation

After suspension polymerization, the polymerization particles were discharged from the reactor, and the reactor was washed with water to observe whether the internal wall and agitator were scaled with the naked eye.

Bovine: As a result of visual observation, scale hardly occurs.

C: As a result of visual observation, the scale is remarkable.

2) particle size distribution and fine particle measurement

Particle size distribution and fine particle content of the suspension polymer resin were measured using a light scattering measurement method, in which light scattered due to the solute in the solution, and thus the size and shape of the particles were determined.

3) particle shape

Observation with the naked eye indicated that the particles were uniformly dispersed and uniformly dispersed, and that the particles were large or large, or stuck together and uneven.

Example 1

<Production of Dispersant>

In order to synthesize 30 g of potassium methacrylate in a three-necked flask with a condenser, 24.2 g of methyl methacrylate and 15.9 g of potassium hydroxide (KOH, 85% purity) were added together with 2000 g of water and reacted for 1 hour at nitrogen atmosphere and room temperature. Add 180 g of sodium metall sulfonate and 700 g of water, and add 45 g of methyl methacrylate, 2,2'-azobis (2-amidinopropane) dihydrochloride (2,2'-Azobis (2-amidinopropane). 0.3g of dihydrochloride) was added and polymerization was started at 50 ° C. When reaction temperature reached 60 degreeC, the methyl methacrylate monomer was divided | segmented and injected 10 times 4.5g every 15 minutes after 15 minutes. After reacting for 6 hours at the same temperature, it was cooled to obtain a 10% aqueous polymer solution.

Suspension polymerization reaction

7.5 g of 2,2'-azobis isobutyronitrile as a polymerization initiator in a monomer of 2.79 kg of methyl methacrylate, 0.6 kg of methyl acrylate and 0.15 kg of methacrylic acid, n as a chain transfer agent -6.6 g of octyl mercaptan (n-octyl mercaptan) was put in a 10 liter reactor, 0.3 g of a dispersant and 15 g of sodium sulfate were put in 6 kg of water, dispersed well, and put into a reactor to carry out suspension polymerization.

After discharging the polymerized particles from the reactor and washing the reactor with water, the scale was not observed when the inner surface and agitator of the reactor were observed.

[Example 2]

In Example 1, the reaction temperature was raised to 60 ° C., and then dropwise addition of methyl methacrylate was started at a rate of 0.6 g / min with a dropping pump, and the dropwise addition was continued for 75 minutes.

[Example 3]

In the initial stage for the temperature increase in Example 1, 15 g of potassium methacrylate, 210 g of sodium metall sulfonate, and 37.5 g of methyl methacrylate were added to the monomer-injected mass at an initial stage, and after 15 minutes when the reaction temperature reached 60 ° C, The procedure was the same except that the methyl methacrylate monomer was divided into five portions of 15 g at 15 minute intervals.

Example 4

In the initial stage for the temperature increase in Example 1, 45 g of potassium methacrylate, 150 g of sodium metall sulfonate, and 10 g of methyl methacrylate were added to the monomer-injected mass, and the reaction temperature reached 60 ° C. after 15 minutes. The same procedure was carried out except that the methyl methacrylate monomer was divided into 10 portions of 2.5 g at 6 minute intervals.

[Example 5]

In Example 1, it carried out similarly except having added 90 g of sodium metalyl sulfonates and 90 g of methacrylic acid 2-sulfo methyl sodium instead of sodium metall sulfonate.

Comparative Example 1

The composition ratio of the dispersant component polymerized in Example 1 was maintained as it was, except that 90 g of methyl methacrylate, which had been separately added before the polymerization and after the completion of the temperature increase, was changed to that added in the input step before the reaction super polymerization.

Comparative Example 2

The same procedure was followed in Example 1, except that 210 g of sodium metall sulfonate and 90 g of methyl methacrylate were used without using potassium methacrylate.

[Comparative Example 3]

The polymerization was carried out in the same manner as in Comparative Example 1 except that 285 g of sodium metall sulfonate, 6 g of potassium methacrylate, and 9 g of methyl methacrylate were added.

[Comparative Example 4]

In Example 1, before the polymerization, 60 g of sodium metall sulfonate, 60 g of potassium methacrylate, and 36 g of methyl methacrylate were added. When the reaction temperature reaches 60 ° C., the methyl methacrylate monomer was added every 6 minutes after 15 minutes. The same procedure was conducted except that 14.4 g each was divided into ten portions.

[Comparative Example 5]

The same procedure was followed in Example 1, except that 180 g of potassium methacrylate and 120 g of methyl methacrylate were used without using sodium metall sulfonate.

In the following Examples and Comparative Examples, the physical properties of the copolymerized dispersants were measured and shown in Table 1.

[Comparative Example 6]

The same procedure was followed in Example 1 except that 2-sulfo methyl sodium methacrylic acid was used instead of sodium metall sulfonate.

[Table 1]

As shown in the above table, it can be seen that the suspension polymerization using the dispersant according to the present invention has excellent polymerization stability, uniform particle shape and less fine powder generation, and significantly reduced generation of scale in the reactor. there was.

Claims (10)

Suspension characterized in that the copolymer homogeneously polymerized in an aqueous solution of a monomer mixture consisting of 10 to 85 wt% of the monomer of Formula 1, 5 to 45 wt% of the monomer of Formula 2 and 10 to 45 wt% of the (meth) acrylic acid ester monomer Dispersant for polymerization.
[Formula 1]

(Wherein R ¹ is H or CH ₃ and M ¹ is any one selected from lithium, sodium, potassium and ammonium salts.)
(2)

(Wherein, R ² is H or CH ₃ , M ² is any one selected from lithium, sodium, potassium, ammonium salt.) The method of claim 1,
Further comprising a monomer of formula (3), 3 to 80 wt% of monomer of formula 1, 0.5 to 60 wt% of monomer of formula (3), 5 to 45 wt% of monomer of formula (2) and 10 to 45 wt% of (meth) acrylic acid monomer A dispersing agent for suspension polymerization, characterized in that the copolymer is a homopolymerized monomer mixture consisting of an aqueous solution.
(3)

(Wherein R ³ is H or CH ₃ , M ³ is lithium, sodium, potassium, ammonium salt, n is an integer of 0 to 3) The method of claim 1,
The (meth) acrylic acid ester monomer is a dispersing agent for suspension polymerization containing any one monomer selected from methyl acrylate, ethyl acrylate, methyl methacrylate or ethyl methacrylate. After putting the monomer and initiator of the following general formula (1) and (2) in aqueous solution, the whole or a part of (meth) acrylic acid ester monomer is continuously or partly thrown in, The manufacturing method of the dispersing agent for suspension polymerization characterized by the above-mentioned.
[Formula 1]

(Wherein R ¹ is H or CH ₃ and M ¹ is any one selected from lithium, sodium, potassium and ammonium salts.)
(2)

(Wherein, R ² is H or CH ₃ , M ² is any one selected from lithium, sodium, potassium, ammonium salt.) 5. The method of claim 4,
Method for producing a dispersant for suspension polymerization further comprising a monomer of the formula (3).
(3)

(Wherein R ³ is H or CH ₃ , M ³ is lithium, sodium, potassium, ammonium salt, n is an integer of 0 to 3) 5. The method of claim 4,
In the continuous or split addition of the (meth) acrylic acid ester monomer, the monomer concentration in the aqueous solution is to be 1.5 wt% or less, characterized in that the suspension dispersing agent production method. Dispersing agent of any one selected from claims 1 to 3 and dispersing agent of any one of the dispersing agent prepared by any one of the production method selected from claim 4, 1 to trivalent cationic electrolyte and vinyl monomer Suspension polymerization method characterized by using. 8. The method of claim 7,
The dispersant is a suspension polymerization method containing 0.005 to 1 parts by weight based on 100 parts by weight of the vinyl monomer. 8. The method of claim 7,
The cationic electrolyte is any one alkali metal cation selected from lithium, sodium, potassium; Or a hydrochloride, sulfate or phosphate salt of an ammonium cation; and containing 0.01 to 2 parts by weight based on 100 parts by weight of a vinyl monomer. delete