KR100684424B1 - Method for preparing polymer latex resin powder using normal pressure slow flocculation-pressurizing aging process - Google Patents

Abstract

The present invention relates to a method for producing a polymer latex resin powder using a slow pressure agglomeration-pressure aging process, the method for producing a polymer latex resin powder having a glass transition temperature of 95 ℃ to 105 ℃, (a) Continuously supplying the polymer latex, the flocculant and the water (b) in the normal pressure slow flocculation tank, the mixture is subjected to atmospheric pressure under a glass transition temperature (Tg) -5 ° C. to a glass transition temperature (Tg))-10 ° C. of the polymer latex. Staying for 3 to 5 minutes to agglomerate, transferring the prepared agglomeration slurry to a aging tank and (c) at a temperature of + 15 ° C. to + 20 ° C. higher than the temperature of the agglomeration tank under pressure of 1.5 to 2.0 kgf / cm 2 in the aging tank. It provides a method for producing a polymer latex resin powder comprising the step of producing a polymer latex resin powder by staying for 30 to 40 minutes. The polymer latex resin powder produced by the present invention has a particle size of 70 to 400 μm or more in terms of particle size of 90 wt% or more, and has an excellent apparent specific gravity.

Polymer latex, flocculation tank, aging tank, slow flocculation

Description

Method for Preparing a Polymer Latex Resin Powder Using a Pressureless Slow Coagulation-Pressurized Aging Process}

1 is a schematic view showing a multi-stage continuous coagulation apparatus for producing a polymer latex resin powder from a polymer latex according to the present invention.

Brief description of the main symbols in the drawings

1: polymer latex supply line 2: flocculant supply line

3: water supply line 4: steam supply line

5: Normal pressure slow flocculation tank 6, 9: High pressure slurry pump

7: steam supply line 8: pressurized aging tank

The present invention relates to a method for preparing a polymer latex resin powder using a slow pressure aggregation-pressurizing aging process, and more specifically, a slow pressure aggregation with a narrow particle size distribution and excellent apparent specific gravity characteristics through a pressure-fast slow aggregation-pressurization aging process. It relates to a method for producing a polymer latex resin using a pressure aging process.                         

The polymer latex resin is a liquid latex resin prepared in the polymerization is obtained as a final powder through agglomeration and aging / drying, wherein the agglomeration and aging temperature conditions are dependent on the inherent glass transition temperature of the polymer latex resin. That is, when the glass transition temperature is 100 ° C. or less, the powder is manufactured through atmospheric coagulation-atmospheric aging, and when 100 ° C. or more, the final powder is obtained under operating conditions of 100 ° C. or higher through pressure coagulation-pressurization aging.

However, in the case of the polymer latex resin having a glass transition temperature of about 100 ° C., problems arise in the practical application in both the case of atmospheric coagulation-atmospheric pressure aging and pressure coagulation-pressure aging. In other words, when the atmospheric coagulation-atmospheric aging process is applied to a resin having a glass transition temperature of 100 ° C, the flocculation temperature that can be operated in the field is at a maximum of 97-98 ° C at atmospheric pressure, In the particle size distribution of the final powder, there is a problem in that the fine powder content is greatly increased, and likewise, it cannot be raised above 99 ° C. at the aging temperature, and thus it is not fully aged and thus gives a poor result not only in particle size but also in appearance.

In addition, pressure coagulation-pressurization aging process is operated under pressure in both coagulation and aging tanks, but it can raise the temperature more than 100 ℃ when pressurized, but latex injected into coagulation tank due to low glass transition temperature of resin Instantaneous hardening problems easily occur. Therefore, in order to avoid such process problems in many factories, the resins having a glass transition temperature of about 100 ° C. are operating under atmospheric pressure aggregation-pressure aging processes while deteriorating particle size distribution.

In order to solve this problem, the present inventors introduced an atmospheric pressure slow-aggregation-pressurizing aging process to enable stable operating conditions even for rubber latex resins near the glass transition temperature of 100 ° C, and at the same time have an excellent particle size distribution and improved apparent specific gravity. A novel method for producing a polymer latex resin powder has been completed.

In order to solve the problems as described above, an object of the present invention is to provide a method for producing a polymer latex resin powder through a normal pressure slow flocculation-pressure aging process.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention
In the method for producing a polymer latex resin powder having a glass transition temperature of 95 ℃ to 105 ℃, (a) continuously supplying the polymer latex, flocculant and water to the atmospheric pressure slow flocculation tank (b) the mixture in the atmospheric slow slow flocculation tank And agglomerated by holding for 3 to 5 minutes at a temperature of 5 ° C to 10 ° C lower than the glass transition temperature of the polymer latex under atmospheric pressure, and transferring the prepared flocculation slurry to a aging tank, and (c) 1.5 to 2.0 kgf / It provides a method for producing a polymer latex resin powder comprising the step of producing a polymer latex resin powder by holding for 30 to 40 minutes at a temperature 15 ℃ to 20 ℃ higher than the coagulation bath temperature under a pressure of cm2.

The coagulant of step (a) may be selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, sulfate, calcium salt, magnesium sulfate and mixtures thereof.                     

The particle size of the polymer latex of step (a) may be 0.05 ~ 0.4 ㎛.

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The flocculant of step (a) may be dissolved in water at a concentration of 5 to 10% and used at 0.5 to 2.5 parts by weight.

The polymer latex resin powder may be 85 to 95% by weight of the powder of 70 to 400 ㎛ size.

Hereinafter, the present invention will be described in detail.

The present invention is a powder recovery method of the polymer latex resin near the glass transition temperature of 100 ℃, while having the same stability of operation as in the existing conventional atmospheric pressure aggregation atmospheric pressure aging process and at the same time excellent particle size distribution in the pressure aggregation-pressure aging process It is characterized by the advantages that can be obtained.

The polymer latex used in the present invention may be prepared by the well-known emulsion polymerization generally.

Such polymer latex is as follows.

In the presence or absence of 20 to 60 parts by weight of butadiene-based rubbery latex prepared by emulsifying and polymerizing 30 to 50 parts by weight of styrene and 50 to 70 parts by weight of butadiene and 1 to 3 parts by weight of crosslinking agent capable of crosslinking polymerization. 1 to 5 parts by weight of a single or complex monomer of 20 to 60 parts by weight of a monomer, 5 to 20 parts by weight of a vinyl cyanide compound, an alkyl group having 1 to 12 carbon atoms and glycidyl acrylate, or the like The polymer latex (A) was continuously added to the latex and graft polymerized, and the glass transition temperature was 101 ° C.

The flocculant used for this invention uses a water-soluble inorganic acid or an inorganic salt. Types thereof include hydrochloric acid, sulfuric acid, phosphoric acid and sulfate, calcium salt, magnesium sulfate, and the like, and the amount of flocculant is limited by the critical concentration according to the latex property.

Each step in the method for producing a polymer latex resin powder according to the present invention will be described with reference to FIG. 1 as follows.

Stage 1: atmospheric slow flocculation tank

In general, a coagulation tank is a device that increases the size of the slurry to a 45 ~ 450㎛ slurry by mixing a polymer latex having a size of about 0.05 ~ 0.4 ㎛ and a coagulant such as an excess of inorganic salts or acids (Rapid Coagulation) . The size distribution of the final powder is most dependent on the agglomeration temperature when the agitation of the coagulation bath is constant.

However, when the rapid flocculation method is applied to obtain the powder in the latex resin near the glass transition temperature of 100 ° C, the required flocculation temperature is around 102-103 ° C but operating at 97-98 ° C lower than the limit of atmospheric pressure aggregation. There is no choice but to. This operational limitation eventually increases the distribution of microparticles in the size distribution of the final powder, and these microparticles reduce the yield of the resin during transport and packaging and act as a factor of deterioration of the working environment due to flying.

Therefore, in order to solve the above problems, the present invention introduces a slow pressure coagulation (Slow Coagulation). Compared to the existing flocculation method using excessive flocculant, slow flocculation induces flocculation in the secondary well region where the energy barrier exists by using the flocculant in the limited region. There is a possibility that it is possible to produce spherical particles by regular filling and to prepare powders having an excellent particle size distribution even at a lower aggregation temperature than the rapid aggregation method.

In order to find the area of the secondary well where slow aggregation is induced, there is theoretically a method based on the graph of the change of the total potential energy through the measurement of zeta-potential, but the measurement error is larger than that of the narrow well. There is a problem that it is difficult to find the correct value.

Therefore, the present invention observes the particle shape change when a small amount of flocculant content is changed under the same temperature conditions and agitation as a criterion for the slow coagulation. The overall particle size is also very uniform, and when it is out of this range, it is based on the fact that it shows irregular particle formation and non-uniform particle size distribution.

The process for producing a latex resin powder based on the slow aggregation is largely composed of two stages of aggregation aging. In the coagulation tank (5), latex, coagulant and water are supplied through the polymer latex supply line (1), the coagulant supply line (2), and the water supply line (3) connected to the lower part of the coagulation tank. Transfer to the top of the aging tank (8) through the pump for slurry (6). In this way, the raw material is injected from the lower part of the coagulation tank and discharged to the upper part, so that a short pass of the slurry, that is, does not sufficiently stay in the coagulation tank and is immediately discharged, compared to the case of the conventional top input / top discharge. The case is greatly reduced and therefore has an advantage in terms of even distribution of residence time.

The L / D (coagulation tank length / diameter) of the coagulation tank applied to the present invention is in the range of 1.5 to 2.0, and the L / D value is larger than that of the general reaction tank, which is 10 to 15 minutes, which is a general residence time in the conventional atmospheric coagulation. This is to compensate for a relatively short residence time. In addition, in the case of the stirrer, considering that L / D is 1.5 to 2, the number of stages of the stirrer is three stages, and the stirrer used is a radial flow without baffles in order to prevent the up and down stirring in the coagulation tank. It is preferable to use four blade-flat paddles to induce. At this time, the ratio (d / D) between the diameter (d) of the stirrer and the diameter (D) of the coagulation tank is preferably in the range of 0.6 to 0.7, which is generally d / D 0.3 to This is because smooth stirring is difficult at the 0.4 level.

The temperature condition of the coagulation bath is preferably a temperature of the glass transition temperature (Tg) -5 ℃ to the glass transition temperature (Tg)-10 ℃, the process temperature using a steam (4) for the high temperature coagulation temperature. It is desirable to adjust.

Moreover, it is preferable for the particle shape and particle size that the residence time in a coagulation tank is 3 minutes-5 minutes. If the residence time exceeds 5 minutes, there is a problem that the particle size deteriorates because the residence time distribution in the coagulation bath is widened.                     

The flocculant is used in an amount of 0.5 to 2.5 parts by weight, and used as an aqueous solution by diluting or dissolving in water to maintain a uniform mixing concentration in the flocculating tank.

When aggregated with respect to the polymer latex (A), the appropriate aggregation temperature is about 92 ~ 93 ℃ based on the total solid content 15%, wherein the flocculant is sulfuric acid and the critical aggregation concentration is 0.6 to 0.7 parts by weight based on the polymer to be.

Step 2: pressurized aging tank

The aging tank is a step of strengthening the hardness by operating in a temperature condition above the glass transition temperature to remove moisture in the particles. However, in the case of a polymer having a glass transition temperature of about 100 ° C., when the ripening is performed at normal pressure, the maximum operating temperature is limited to around 98 to 99 ° C., so it is difficult to expect an effect through aging.

Therefore, in the present invention, the particle size distribution is determined through the slow-pressure coagulation at atmospheric pressure, and in the pressure aging tank, the internal pressure of the aging tank is 1.5 to 2.0 kgf / cm 2 so that the aging can be sufficiently carried out above the glass transition temperature. It was made to operate for 30 to 40 minutes at the temperature of 15 degreeC thru | or coagulation tank temperature +20 degreeC, and it made the single particle | grains by forming interpenetration between polymer chains.

In the process, the slurry produced in the coagulation tank is transferred from the bottom of the coagulation tank to the top of the aging tank through a pump for high pressure slurry. In the aging tank, since the shape of the slurry particles transferred from the coagulation tank is hardened without changing, the structure of the aging tank or the type of agitator is not significantly affected. However, in order to induce smooth flow in the aging tank, it is preferable to use a down-flow pitched paddle type provided with a baffle.

In the case of the polymer latex (A), the temperature conditions of the pressure aging tank is preferably 105 to 110 ℃ under 2.0kgf / ㎠.

The polymer latex resin powder prepared through the coagulation-maturation process under such conditions is not less than 90% by weight of 70 to 400 μm, unlike the conventional commercial polymer resin having a widely distributed particle diameter in the range of 74 to 841 μm. The fine powder of less than 70 µm and the powder of 400 µm or more are excellent at 5% by weight or less, respectively.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the examples.

Example 1

A polymer latex (A) having a solid content of 42% was supplied simultaneously with 7.1 L / hr of sulfate diluted to 5% at a flow rate of 121 L / hr and 211 L / hr of water to the bottom of the coagulation tank. The temperature is adjusted to 3 minutes and 92 ° C. respectively to induce aggregation. After the agglomerated slurry is transferred from the bottom of the coagulation tank to the top of the aging tank through a high pressure slurry pump, the aging tank was aged for 30 minutes at a aging temperature of 110 ℃ under 2.0kgf / ㎠ pressure to achieve the aging.

After aging, the polymer latex resin powder is transferred to a storage tank through a pump, and the particle size distribution and physical properties of the polymer latex resin powder obtained through the above process are shown in Table 1 below.

Example 2

The particle size distribution and physical properties of the polymer latex resin powder obtained in the same manner as in Example 1 except that the operating temperature of the flocculation tank in Example 1 is 95 ° C. and the residence time is 5 minutes are shown in Table 1 below. It was.

Example 3

The particle size distribution and physical properties of the polymer latex resin powder obtained in the same manner as in Example 1 except that the pressure in the aging tank is 1.5kgf / cm2 and the operating temperature is 105 ° C in Example 1 Table 1 shows.

Comparative Example 1

The particle size distribution and physical properties of the polymer latex resin powder obtained in the same manner as in Example 1 except that the operating temperature of the aging tank in Example 1 is 95 ℃ and the operating pressure is shown in Table 1 below It was.

Comparative Example 2

The particle size distribution and physical properties of the polymer latex resin powder obtained in the same manner as in Example 1 except that the operating temperature of the aging tank in Example 1 is 99 ℃ and the operating pressure atmospheric pressure are shown in Table 1 below. .

Comparative Example 3

Except that the coagulation temperature and the process pressure of the coagulation tank in Example 1 is 103 ℃ / 1.5kgf / cm2, respectively, except that the maturing temperature and the process pressure is 105 ℃ / 1.5kgf / cm2, respectively Particle size distribution and physical properties of the polymer latex resin powder obtained by the same method as described in Table 1 are shown in Table 1 below.

[Comparative Example 4]

Except that the coagulation temperature and the process pressure of the coagulation tank in Example 1 is 105 ℃ / 1.5kgf / cm2, respectively, except that the maturing temperature and the process pressure is 110 ℃ / 2.0kgf / cm2, respectively Particle size distribution and physical properties of the polymer latex resin powder obtained by the same method as described in Table 1 are shown in Table 1 below.

As described above, the polymer latex resin powder produced according to the present invention has a particle size of 70 to 400 μm or more at 90 wt% or more, and fine powders of less than 70 μm and powders of 400 μm or more, respectively. It can be up to 5% by weight and at the same time has an apparent specific gravity.

Although the present invention has been described in detail with reference to specific examples described in the embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention, and the appended claims It is also natural to fall within the scope.

Claims (6)

In the method for producing a polymer latex resin powder having a glass transition temperature of 95 ° C to 105 ° C, (a) supplying a polymer latex, a flocculant, and water to an atmospheric pressure slow flocculation tank; (b) condensing the mixture in the atmospheric slow-pressure flocculation tank by holding the mixture under atmospheric pressure at a temperature of 5 ° C. to 10 ° C. lower than the glass transition temperature of the polymer latex for 3 to 5 minutes, and transferring the prepared flocculation slurry to a aging tank; And (c) preparing a polymer latex resin powder by staying at a temperature of 15 ° C. to 20 ° C. for 30 to 40 minutes higher than the flocculation bath temperature under a pressure of 1.5 to 2.0 kgf / cm ² in a aging tank; Method for producing a polymer latex resin powder comprising a. The method of claim 1, The method of producing a polymer latex resin powder, characterized in that the flocculant of step (a) is selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, sulfate, calcium salt, magnesium sulfate and mixtures thereof. The method of claim 1, Method for producing a polymer latex resin powder, characterized in that the particle size of the polymer latex of step (a) is 0.05 ~ 0.4 ㎛. delete The method of claim 1, The coagulant of step (a) is dissolved in water at a concentration of 5 to 10% of the polymer latex resin powder manufacturing method, characterized in that used in 0.5 to 2.5 parts by weight. The method of claim 1, The polymer latex resin powder is a method for producing a polymer latex resin powder, characterized in that the powder of 70 to 400 ㎛ size 85 to 95% by weight.

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