JPH04150934A - Preparation of emulsion resin - Google Patents

Abstract

PURPOSE:To prepare an emulsion resin generating no destruction of particles and reduced in the generation of floc by adding a polymerizable org. compound, a liquid medium and a polymerization initiator to the annular part of a coaxial double rotary cylinder wherein an outer cylinder is stopped and an inner cylinder is rotated. CONSTITUTION:A polymerization initiator is received in catalyst tanks 1, 2 and a monomer emulsion consisting of a liquid medium, which consists of a polymerizable org. compound such as styrene and a nonionic surfactant, and water is received in a monomer tank 3. The polymerization initiator and the monomer emulsion are continuously dripped in the annular part of a coaxial double rotary cylinder from the respective tanks 1, 2, 3 while an inner cylinder 9 is rotated at proper rpm by a motor 4 and automatically mixed by the rotation of the inner cylinder 9 and a radical is generated by redox reaction to start polymerization. Cooling water is passed through a pipe inlet 10 and an outlet 11 to control the temp. in the system. The supplied catalyst aqueous solution and the monomer emulsion are converted to a polymer emulsion which in turn enters a product receiving tank 12. By this method, a product reduced in particle size distribution is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for emulsion polymerization of aqueous emulsions by using coaxial double rotating cylinders.

(Prior Art) As a conventional emulsion polymerization method, a method is known in which a polymerizable organic compound, an emulsified liquid, and a polymerization initiator are charged into a seed reactor having a stirring blade, and an emulsion resin is obtained by batch polymerization.

Furthermore, as a conventional continuous emulsion polymerization method, a method is known in which a polymerizable organic compound, an emulsified liquid, and a polymerization initiator are continuously supplied to a loop-shaped tubular reactor, a multistage stirring tank array, etc. to obtain an emulsion resin. ing.

However, in the case of using a seed type reactor having stirring blades, particles are destroyed by the stirring blades, resulting in significant floc formation and adhesion to the walls of the reactor.

In addition, the loop-shaped tubular reactor is, for example,
A reactor consisting of a loop-shaped pipe as disclosed in Publication No. 272, and a circulation pump that serves to mix the liquid in the loop and the supplied liquid and circulate both. A jacket is provided on the outside to enable heating and cooling. The reactor has a relatively small volume and is characterized by a large heat transfer surface relative to its volume. Typical pipe circulation rates are about 25 times higher than the external addition rate of polymerization liquid. Therefore, the shearing force within the pump is large, particles are easily broken, and floc formation and adhesion to walls are significant.

A multi-stage stirring tank array refers to a cascade-like reaction tank group in which several reaction tanks equipped with stirring blades are connected in series, and the amount corresponding to the supply amount overflows and flows to the next stirring tank to continue polymerization. , an emulsion with a wide particle size distribution is produced when the residence time distribution in the tank is wide. Therefore, in this device, particle destruction occurs due to the stirring blades, and a large amount of flocs is generated and adheres to the blades and wall surfaces.

(Problems to be Solved by the Invention) The purpose of the present invention is to:
It is an object of the present invention to provide a method for producing an emulsion resin in a state where mechanical shear is low, such as without causing particle destruction and with little generation of flocs.

(Means for Solving the Problems) As a result of intensive research to solve the above problems, the present inventors have completed the present invention.

That is, the present invention provides a method for producing an emulsion resin by carrying out emulsion polymerization of a polymerizable organic compound in a liquid medium. This is a method for producing an emulsion resin characterized by adding an organic compound (A), a liquid medium (B) for emulsion polymerization of the polymerizable organic compound (A), and a polymerization initiator (C).

The polymerizable organic compound (A) used in the present invention 4 generally refers to a substance that polymerizes under a radical-generating catalyst,
For example, styrene, vinyl compounds such as vinyl acetate, compounds having α-alkyl acryloyl groups such as methyl methacrylate, ethyl methacrylate, and methacrylic acid, and compounds having an α-alkyl acryloyl group such as ethyl acrylate, butyl acrylate, and acrylic acid. Examples include compounds that have

In order to make a polymerizable organic compound into an aqueous emulsion, various surfactants are used as the liquid medium (B). In general, nonionic surfactants such as polyoxyethylene fatty acid esters and polyoxyethylene alkylphenyl ethers, anionic Fit activators such as sodium alkyl sulfate, sodium alkylaryl sulfonate, or their ammonium salts, and bobivinyl Protective colloids such as alcohol and hydroxyethyl cellulose are used.

As shown in Fig. 1, the coaxial rotating cylinder used in the present invention consists of an inner cylinder and an outer cylinder that share a central axis, and the outer cylinder is fixed.
When the inner cylinder is rotated at a certain rotation speed, the liquid in the annular part between the two old cylinders forms a donut-shaped vortex (
tiller vortex). The generation of vortices is caused by Ta described below.
Defined by number.

-d Ta= ×(a/R1) I/1 μ R1: Outer diameter of the inner cylinder d: Width of the annular portion of the inner and outer cylinders W: Inner cylinder rotational angular velocity P: Liquid density μ: Liquid viscosity As the Ta number increases ( 2000 or more), the vortex disappears and the whole becomes a unified turbulent state, which is not preferable. Also T
If the a number is too small (40 or less), no vortex will be generated and sufficient mixing will not occur, which is not preferable.

Therefore, the Ta number is preferably in the range of 60 to 600 since moderate vortices are generated.

Since the mass transfer across this high-volume boundary (especially inward flow) is very small, the pair of vortices has the properties of a Sochi stirred tank. The present invention focuses on the high degree of independence of such a coaxial double-rotating cylindrical flow system, and attempts to carry out a so-called batch reaction batchwise and continuously.

Next, a method for continuously producing emulsion resin will be explained along FIG. 3.

A reducing agent such as sodium metabisulfite is placed in the catalyst tank 1, an oxidizing agent such as potassium persulfate is placed in the catalyst tank 2, and a monomer emulsion liquid is placed in the monomer tank 3. Motor 4 rotates the inner cylinder at an appropriate speed (
While rotating at a speed of about 60 to ioorpm), drops are continuously dropped from each type onto the annular portion of the coaxially rotating cylinder. The catalyst and monomer are mixed automatically by the rotation of the inner cylinder, and radicals are generated by a redox reaction to initiate polymerization.

The temperature inside the system gradually rises from room temperature, and when it reaches a specified temperature, the temperature is controlled to an appropriate temperature by passing cooling water through the system.

The polymerization temperature is 40-80°C, preferably 40-60°C. If the temperature is higher than 80°C, particle fusion will occur;
If it is lower, the conversion of monomer to polymer will not be sufficient within the residence time of the reactor.

The supplied catalyst aqueous solution and monomer emulsion are converted into a polymer emulsion, and the product receiver is introduced into the tank 10 through an overflow line. If the monomer conversion rate is insufficient, it is possible to increase the conversion rate by adding a catalyst.

The particle size distribution of the emulsion resin obtained in the present invention is T
Due to the characteristics of the a-vortex, it is relatively narrow, so it is suitable for use as seed particles in the production of emulsion resins. If such an application scale is used, the solids content of the system will be less than 40%.

It is also preferable to connect several such devices in series and mix the monomer emulsion and the catalyst with the product of the previous step in each step to carry out seed polymerization continuously.

According to such a method, an emulsion resin having a solids content of 50 to 60% can also be obtained, and a product having a particle size distribution close to that obtained by batch polymerization can be obtained.

The monomer may be added to the reaction system in a pre-emulsified state, or the monomer and the emulsifying liquid (aqueous surfactant solution) may be added to the reaction system separately. If added separately, it will take time for the monomers to emulsify, so it is necessary to allow a slightly longer residence time.

As the polymerization initiator (C), a general redox polymerization initiator is used, and as an oxidizing agent, inorganic peroxides such as potassium persulfate and ammonium persulfate, and 41 peroxides such as t-butyl hydroperoxide are used. Examples include one type selected from among the above, and a combination of one type selected from among sodium metabisulfite, sodium bisulfite, and sodium formaldehyde sulfoxylate as the reducing agent. The amount of this polymerization initiator (C) is 0 relative to the polymerizable organic compound (A).
．． 2-3% by weight is used.

(Example) The present invention will be described below with reference to Examples.

Note that all parts and percentages (%) in the examples are based on weight.

Example 1 40 parts of a monomer emulsified solution and 50 parts of deionized water were added to the reactor shown in Fig. 1 (inner volume 1.51), and the temperature was heated to about 40°C.
After heating to , add 0.0% sodium pyrosulfite. After adding 25 parts of ammonium persulfate and 0.25 parts of ammonium persulfate to start polymerization, 570 parts of an emulsified solution of the following (1), (II) and monomers were added.
The mixture was added dropwise over time to obtain an emulsion polymer.

Monomer emulsification solution Deionized water 146.4 parts Emulgen 9
31 32.9 parts (Kao Corporation product, anionic emulsifier) Neugen EA-1427, 5 parts (Daiichi Kogyo Seiyaku Co., Ltd. product nonionic emulsifier) Hytenol N-087, 5 parts (Daiichi Kogyo Seiyaku Co., Ltd. product, nonionic emulsifier) ) Product anionic emulsifier ) Butyl acrylate 220 parts Styrene
183 parts 80% acrylic acid
When 15.3 parts of the obtained emulsion polymer was taken out and adhesion to the inner cylinder and outer cylinder was examined, almost no adhesion was observed.

The properties of the obtained emulsion polymer solution were as shown in Table 1.

Comparative Example 1 Emulsion polymerization was carried out in the same manner as in Example 1 in a weighing reactor equipped with a stirring blade shown in FIG. 2 to obtain an emulsion polymer.

After the obtained emulsion polymer was extracted, it was examined for adhesion to the stirring blades and the inner wall of the reactor, and significant adhesion was observed.

The properties of the obtained emulsion polymer solution were as shown in Table 1.

Example 2 Polymerization catalyst solutions (m) and (IV) were continuously charged at 100 ml/min each and monomer emulsified solution at 45 ml/min from the upper part of the reactor shown in Fig. 3, and the temperature in the system was kept at about 4.
While maintaining the temperature at 0°C, it was continuously extracted from the lower part of the reactor to obtain an emulsion polymer.

Polymerization catalyst solution (m) 0.3 of sodium formaldehyde sulfonate
% deionized aqueous polymerization catalyst solution (TV) 0.3% ammonium persulfate deionized aqueous monomer emulsified solution (amount charged per 100 parts of emulsified solution) Deionized water 51 parts → Temul P3 1.5 parts (Kao Corporation) Product, anionic emulsifier) Neugen EA-190D 1.1 parts nonionic emulsifier manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Neugen EA-17O3 (product manufactured by Daiichi Kogyo Seiyaku Co., Ltd. 1.1 parts nonionic emulsifier) Neugen 7EA-800, 6 parts (nonionic emulsifier manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Ethyl acrylate 35.0 parts Methyl methacrylate 7. 0 parts methacrylic acid
2.3 parts N-methylol acrylamide (60% aqueous solution) 1.0 part After the reaction was continued for 6 hours, adhesion to the inner cylinder and outer cylinder was examined, and almost no adhesion was observed.

The properties of the emulsion polymer solution obtained were as shown in Table 1.

Example 3 Polymerization catalyst solutions (I) and (It) were poured into the upper part of the reactor shown in Fig. 3 at a rate of 59 ml/min, and a monomer emulsified solution was added at 1/min.
Continuously charge 07ml/min to bring the temperature inside the system to about 60℃.
While maintaining the temperature at °C, the same amount was continuously withdrawn from the lower part of the reactor to obtain an emulsion polymer.

Polymerization catalyst solution (1) Sodium pyrosulfite deionized water Polymerization catalyst solution (n) Ammonium persulfate deionized water Monomer emulsification solution (amount charged per 100 parts of emulsification solution) Deionized water Emalgen 931 (Kao Corporation product nonionic emulsifier) Neugen EA-142 (Daiichi Kogyo Seiyaku Co., Ltd. Nonionic emulsifier) 0.4 parts 100 parts 0.4 parts 100 parts 24 parts 5.4 parts 1°1 part Hytenol N-08 (Daiichi Kogyo Seiyaku Co., Ltd.) Anionic emulsifier) Butyl acrylate 1.0 parts Styrene 80% Acrylic acid 36.0 parts 30.0 parts 2.5 parts After continuing the reaction for 5 hours, the emulsion polymer was extracted from the reactor and its adhesion to the inner and outer cylinders was checked. Upon inspection, no adhesion was found.

The properties of the obtained emulsion polymer solution were as shown in Table 1.

Comparative Example 2 The lower part of the reactor shown in Figure 4 was continuously charged with the polymerization catalyst solutions A and B of Example 2 at 127 ml/min each and with the monomer emulsified solution at 57 ml/min, and the temperature in the system was lowered to 4.
While maintaining the temperature at 0''C, the same amount was taken out from the upper part of the reactor to obtain an emulsion polymer. After the reaction was continued for 6 hours, the adhesion to the stirring blades and the inner wall of the reactor was examined, and significant adhesion was observed.

Table 1 shows the properties of the obtained emulsion polymer.

Comparative Example 3 The polymerization catalyst solution (I) and (n
) at 10.4 ml/min each, and 19 ml/min of monomer emulsification solution C.
/ minute while continuously charging and maintaining the temperature in the system at 60°C while operating the pump and performing recirculation through the ring.
The same amount of the charged liquid was taken out of the system through a T-shaped liner to form a product.

The resulting product had a large number of blocks and a wide particle size distribution, making it unsuitable for use. In addition, there was significant adhesion to the initial pipe wall of the loop reactor, requiring disassembly and maintenance.

Table 1 shows the properties of the obtained emulsion polymer.

The measurement method for each property in Table 1 is as follows.

Table 1 (1) Viscosity measurement Measurement was performed at 25°C using a BM type viscometer.

Rotor #1 was used, and the rotation speed was 60 rpm.

(2) PH measurement Measured using a constant H meter.

(3) Measurement of solid content Solid content means non-volatile content per gram of resin. Approximately 5 g of the resin solution was accurately weighed, dried in a dryer at 105° C. for 2 hours, the weight was measured, and the weight was divided by the sample amount.

(4) Particle size measurement The emulsion polymer solution was diluted to 1-200 μg/ml) and measured using a Coulter counter (model N4S, manufactured by Furukyu Electron Co., Ltd.).

(Effects of the Invention) The method for producing an emulsion resin of the present invention brings about the following effects. That is, (1) Mechanical particle destruction caused by stirring blades and circulation pumps is small, so there is little splatter or adhesion to the reactor wall. ■Since particle size changes over time are small, product quality fluctuations are small and products with a narrow particle size distribution similar to batch processes can be obtained. Therefore, the emulsion resin obtained in the present invention is suitable for use as a sheep in the production of emulsion resin.

[Brief explanation of drawings]

Figure 1 shows a flow diagram of batch emulsion polymerization in coaxial double rotating cylinders, Figure 2 shows a flow diagram of batch emulsion polymerization with stirring blades, and Figure 3 shows a flow diagram of batch emulsion polymerization in coaxial double rotating cylinders. Fig. 4 shows a flow diagram of continuous emulsion polymerization in a multi-stage stirring tank array, and Fig. 5 shows a flow diagram of continuous emulsion polymerization in a loop-shaped back type reactor. show. 1.2; Catalyst tank, 3; Monomer tank, 4; Motor 4'; Metering pump, 5; Reaction can, 6; Jacket 7; Stirring blade, 7-
; Partition plate, 8; Outer cylinder, 9; Inner cylinder, 10; Cooling water inlet, 11; Cooling water outlet, ; Product receiving tank, ; Circulation pump, ; Pressure control device, 15; Vibrator

Claims (1)

[Claims] 1. In a method for producing an emulsion resin by carrying out emulsion polymerization of a polymerizable organic compound in a liquid medium, an annular portion of a coaxial double rotating cylinder in which the outer cylinder is stationary and the inner cylinder is rotated; A method for producing an emulsion resin, which comprises adding a polymerizable organic compound (A), a liquid medium (B) for emulsion polymerization of the polymerizable organic compound (A), and a polymerization initiator (C) to. 2. In a method for continuously producing an emulsion resin by carrying out continuous emulsion polymerization of a polymerizable organic compound in a liquid medium, in the annular part of a coaxial double rotating cylinder in which the outer cylinder is stationary and the inner cylinder is rotated, A polymerizable organic compound (A) and a liquid medium (B) for emulsion polymerization of the polymerizable organic compound (A)
and a polymerization initiator (C) are continuously added.