KR20040039935A - Method for Preparing Powder of High Macromolecule Latex Resin - Google Patents

Abstract

PURPOSE: Provided is a method for preparing polymer latex resin powder through continuous aggregation in multi-stage tanks, which controls thermal decomposition rate by changing aggregation conditions while maintaining uniform particle size distribution. CONSTITUTION: The method for preparing polymer latex resin powder comprises the steps of: (a) introducing 0.3-0.4 parts by weight of an emulsifier to 100 parts by weight of polymer latex in a latex tank; (b) supplying polymer latex, a first aggregating agent and water successively to a first aggregation tank; (c) maintaining the mixture in the first aggregation tank(4) at a Tg of -40 deg.C to -30 deg.C for 2-5 minutes to aggregate the mixture and transferring the aggregated slurry to a second aggregation tank(9); (d) adding a second aggregating agent to the mixture, and maintaining the mixture in the second aggregation tank(9) at a temperature higher than that in the first aggregation tank(4) by +3 to +10 deg.C for 10-25 minutes to further aggregate the mixture and transferring the aggregated slurry to a first aging tank(11); (e) aging the slurry in the first aging tank(11) at a temperature higher than that in the second aggregation tank(9) by +5 to +20 deg.C for 60-90 minutes and transferring the aged slurry to a second aging tank(14); and maintaining the slurry in the second aging tank(14) at a temperature higher than that in the first aging tank(11) by +10 to +20 deg.C for 60-90 minutes.

Description

Method for preparing polymer latex resin powder {Method for Preparing Powder of High Macromolecule Latex Resin}

The present invention relates to a method for producing a polymer latex resin powder, and more specifically, to a coagulation condition while maintaining improved properties including uniform particle size distribution and apparent specific gravity and caking, which are advantages of the slow aggregation method, through a multi-step continuous agglomeration process. It relates to a method for producing a polymer latex resin powder that can control the thermal decomposition rate by changing the processing characteristics.

Pyrolysis of PVC resin in processing equipment is generally as follows. When PVC is injected into a processing machine and processing starts, the melting of PVC occurs due to friction and shear stress between the PVC particles and between the PVC particles and various additive particles. At this time, the decomposition of PVC begins to occur due to frictional heat and mechanical shear, especially during the process, some of the hydrogen chloride in PVC is removed, causing the PVC chain to break. The radicals thus generated promote the crosslinking reaction of PVC. The progress of this process is indicated by discoloration, carbonization, and viscosity increase of the resin. In fact, the decomposition of PVC begins to occur between 80 ° C and 100 ° C.

The physical properties to evaluate in order to quantitatively compare the pyrolysis process during PVC processing include the pyrolysis rate in the extruder. The pyrolysis rate represents the time when the PVC particles start to melt in the extruder and decay into primary particles (range: 0.6 ~ 0.8㎛) from the initial grain state (range: 50 ~ 250㎛) of PVC. However, this pyrolysis rate is closely related to extrusion productivity in terms of processing of the resin, and it is a physical property to be carefully managed because there is a problem that PVC is excessively pyrolyzed when the pyrolysis rate exceeds the standard.

In the case of the impact modifier latex described in the present patent, the impact strength improvement of PVC is mainly used, but at the same time, it is known to play a role of improving the processability of PVC. Therefore, many patents propose a variety of impact modifier polymerization method for controlling the thermal decomposition rate of PVC.

However, most of these attempts are made through the change of polymerization prescription such as molecular weight, rubber content, crosslinking degree control, and even though the thermal decomposition rate is changed by prescription control, other properties are likely to change, thus it is difficult to adjust the balance between the properties again. There is this.

Accordingly, the present inventors have completed a method for preparing a polymer latex resin powder which can improve impact strength by controlling a thermal decomposition rate using a flocculant and an emulsifier in a multi-step continuous coagulation process.

Accordingly, the present invention is provided to solve the problems of the prior art as described above,

An object of the present invention is to provide a method for producing a polymer latex resin powder through a multi-step continuous agglomeration process.

Another object of the present invention is to prepare a polymer latex resin powder for controlling the thermal decomposition rate of the processing characteristics by changing the coagulation conditions while maintaining the improved characteristics including the uniform particle size distribution and apparent specific gravity and the caking which is an advantage of the slow aggregation method It is to provide.

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

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: primary flocculant supply line

3: water supply line 4: primary coagulation tank

5: steam supply line 6: primary flocculation tank overflow line

7: steam supply line 8: secondary flocculant supply line

9: secondary flocculation tank 10: secondary flocculation tank overflow line

11: 1st aged tank 12: Steam supply line

13: 1st aged tank overflow line 14: 2nd aged tank

15 steam supply line 16 secondary aging tank overflow line

The method for producing a polymer latex resin powder according to the present invention (a) 0.3 to 0.4 parts by weight of an emulsifier to 100 parts by weight of the polymer latex to the polymer latex storage tank to improve the stability of the latex, the first flocculant is induced to slow aggregation Stably coping with small changes in the field by widening the use area, and controlling the thermal decomposition rate by generating internal lubricant in the impact modifier in response to the secondary flocculant to be introduced in the subsequent process; (b) continuously supplying polymer latex, primary flocculant and water to the primary flocculation tank; (c) In the primary flocculation tank, the mixture is first agglomerated by holding the mixture at a glass transition temperature (Tg) -40 ° C to a glass transition temperature (Tg) -30 ° C for 2 to 5 minutes, and the prepared primary flocculation Transferring the slurry to a secondary flocculation tank; (d) primary flocculation tank temperature in the secondary flocculation tank with the addition of the secondary flocculant for controlling the thermal decomposition rate and the complete coagulation of unaggregated flocculation tank temperature from +3 ℃ to the first flocculation tank temperature +10 ℃ After the second agglomeration by holding for 10 to 25 minutes at a temperature of the step of transferring the prepared secondary flocculation slurry to the primary aging tank; (e) In the first aging tank, the secondary flocculation slurry is first aged by staying at the temperature of the secondary flocculation tank temperature at + 5 ° C. to the secondary flocculation tank temperature at + 20 ° C. for 60 to 90 minutes, and the prepared primary Transferring the aged slurry to the secondary aging tank; And (f) preparing the polymer latex resin powder by maintaining the primary aging slurry in the secondary aging tank for 60 to 90 minutes at the temperature of the primary aging tank temperature +10 ℃ to the temperature of the primary aging tank +20 ℃ It is made, including.

The primary coagulant of step (b) and the secondary coagulant of step (c) are at least one selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, sulfate, calcium salt and magnesium sulfate. The particle size of the polymer latex of step (b) is 0.05 ~ 0.4 ㎛. The primary coagulant of step (b) is diluted to a concentration of 5 to 10% in water and used at 0.5 to 2.5 parts by weight based on the polymer latex.

The primary coagulation slurry of step (c) is creamy. The secondary coagulant of step (d) is used in 3 to 8 parts by weight based on the polymer latex. The powder having a size of 70 to 400 μm in the polymer latex resin powder is 85 to 97 parts by weight based on the total weight of the polymer latex resin powder.

The present invention also provides a polymer latex resin powder prepared by the above method.

Hereinafter, the present invention will be described in detail.

Unlike the rapid flocculation method using the conventional excessive flocculant, the present invention aggregates near the critical flocculation concentration to form particles, and then aggregates the method of preparing a polymer latex resin powder and PVC impact modifier to obtain a final powder through aging. It includes the technology to control the thermal decomposition rate during the extrusion process of PVC by changing the process conditions.

The present invention relates to a method for recovering a polymer latex resin having a size of 70 to 400 ㎛ 85% by weight or more by adding a polymer latex having a size of about 0.05 ~ 0.4 ㎛ and a flocculant such as inorganic salts or acids. In latex storage tanks, a small amount of emulsifier is added before flocculation to improve the stability of the latex, broaden the area of use of the primary flocculant to induce slow flocculation, and react with the secondary flocculant to be introduced in the subsequent process. In the first flocculation tank and the first flocculation tank through the short dwell time to induce slow aggregation with a small amount of flocculant to form a creamy aggregate having a viscosity that can be stirred, in the second flocculation tank Compared to the bath, the long residence time and the thermal decomposition rate condition to be controlled and the complete coagulation The flocculating agent is further added with an amount of secondary flocculant, and then the slurry passed through the primary and secondary flocculation tanks is transferred to the primary aging tank and the secondary aging tank, and the primary and secondary In the aging tank, the hardness of the aggregated particles is enhanced.

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

Such polymer latex is an example

First, one or two or more selected from acrylic or methacrylic ester monomers having 1 or 2 carbon atoms is 80 to 99 parts by weight, and acrylic rubber latex 20 emulsified and polymerized with 0.5 to 1.0 parts by weight of a crosslinking agent capable of crosslinking polymerization. 1 to 50 parts by weight of acrylonitrile monomer, 1 to 100 parts by weight of methacryl or acrylic ester monomer, 1 to 90 parts by weight of vinylaromatic monomer, and 1 to 10 parts by weight of a crosslinking or graft agent copolymerizable therewith in the presence of -80 parts by weight. A polymer latex (A) in which the monomer mixture obtained by mixing the parts is continuously added to the rubber latex at 20 to 80 parts by weight based on the total amount and graft polymerized; or

Second, in the presence of 20 to 60 parts by weight of butadiene-based rubbery latex prepared by emulsion polymerization of 30 to 50 parts by weight of styrene, 50 to 70 parts by weight of butadiene and 1 to 3 parts by weight of crosslinkable polymerizable crosslinking agent, Or 1 to 5 parts by weight of a single or complex monomer of 20 to 60 parts by weight of a complex monomer, 5 to 20 parts by weight of a vinyl cyanide compound, at least one alkyl acrylate having a C1-12 alkyl group and glycidyl acrylate Polymer latex (B) and the like, which are continuously added to rubbery latex and graft polymerized, can be used.

The flocculant used in the present invention is a primary flocculant or a secondary flocculant, and a water-soluble inorganic acid or an inorganic salt is used. Types of hydrochloric acid, sulfuric acid, phosphoric acid and sulfate, calcium salt, magnesium sulfate, etc., the primary coagulant is limited by the critical concentration according to the latex properties, the secondary coagulant is to control the level of pyrolysis rate and uncoagulated Depending on the degree, it is usually preferred to use within the range of 5 to 8 parts by weight of the total solid content.

Emulsifiers used to prepare the latex and to improve the stability of the latex before the first aggregation is used sodium lauryl sulfate (Sodium Lauryl Sulfate), sodium dioctylsulfosuccinate (Sodium dioctylsulfosuccinate) and the like.

In each step of the invention the material is transferred to the next step by an overflow method.

Rapid coagulation using an excess of coagulant has no energy barrier, so the coagulation process is very fast and the process of entanglement with each other becomes quite disordered, resulting in an irregular shape of the final particles, whereas slow coagulation Since aggregation occurs in the region of the secondary well where the energy barrier is present, the aggregation rate is slow and there is a possibility of rearrangement between particles, so that spherical particles can be produced by regular filling.

In order to find the area of the secondary well in which slow aggregation is induced, there is theoretically a method based on the graph of the change of the total potential energy by measuring the zeta-potential, but this method is measured in comparison with the secondary well of the narrow area. There is a problem that it is difficult to find the correct value because the error is large. Therefore, the present invention observes the particle shape change when a small amount of flocculant content is increased under the same temperature conditions and agitation as a criterion for slow agglomeration, and thus the particle shape is spherical at the time of slow coagulation. In addition, the overall particle size becomes very uniform, and when it is out of this range, it is based on the fact that it shows irregular particle generation and non-uniform particle size distribution.

The process of the present invention based on the slow coagulation is composed of five stages, and coagulation and aging are carried out in two stages, respectively.

The process of the invention is described in detail below with reference to the accompanying drawings.

Step 1: Polymer Latex Storage Tank

Most of the latex after polymerization is stored in a storage tank and then transferred to the next stage according to the production plan of the post-treatment process including flocculation. At this time, 0.3 to 0.4 parts by weight of an emulsifier is added to the latex storage tank to induce slow coagulation in a subsequent process. This emulsifier addition imparts chemical stability in the latex and thus has the effect of lowering the rate of aggregation in subsequent flocculation processes. In addition, it is important to widen the range of primary coagulant so that stable slow coagulation can be induced when applied to the actual process in order to apply relatively narrow coagulation range to the site. This range of coagulant usage can be extended to adequately cope with many of the changes expected in the field application. The feeding position is preferably put into the storage tank before the agglomeration is carried out. When the agglomeration is carried out in the 1 / 2th flocculation tank in which the agglomeration is in progress, the apparent specific gravity and the powder characteristics of the powder are improved as compared to the case where the emulsifier is not added. The stabilization and coagulation of at the same time occurs, so the efficiency can be seen as falling. In addition, the emulsifier put into the storage tank plays an important role in relation to the processing characteristics, after blending the emulsifier to the polymerized impact modifier latex, and then aggregated using a metal salt such as calcium chloride or magnesium sulfate, finally obtained These compounds are present inside and on the surface of the impact modifier particles in the form of the corresponding metal salts of fatty acids (eg calcium stearate, magnesium stearate, etc.). These salts are widely known as lubricants added when processing PVC resins. These reactants penetrate into the molecules of the polymer material during processing, causing the chains to slide together, leading to intermolecular flow, and this flow facilitates extrusion, resulting in a higher thermal decomposition rate.

Stage 2: Primary Coagulation Tank

The primary coagulation tank 4 has a viscosity that can be stirred by adding a polymer latex having a size of about 0.05 to 0.4 μm and a coagulant such as inorganic salts or acids to induce slow coagulation with a small amount of coagulant through a short residence time. Forming a creamy aggregate.

In the primary coagulation tank 4, the determination of the critical aggregation concentration is very important. In the critical aggregation concentration, the shape of the particles is spherical and the overall distribution is very uniform. This amorphous form results in an irregular particle shape when the critical concentration is exceeded, and the formation of fine particles of 70 µm or less is increased. Therefore, in the case of slow aggregation, the determination of such critical concentration is very important.

Slow coagulation is influenced by the aggregation temperature and the total solid content in addition to the critical aggregation concentration.In the case of the aggregation temperature higher than the reference temperature, the sphericity and shape of the particles become better under the critical aggregation concentration, but the particle size of the whole particles If it becomes larger in proportion and is lower than the reference temperature, the particle size decreases and the spherical shape and shape of the particles deteriorate. Therefore, it is important to determine the critical aggregation concentration by selecting the appropriate aggregation temperature and the content of the coagulant. In the determination of the concentration, it is difficult to discriminate with the naked eye. Therefore, it is preferable to use an optical microscope with various magnifications.

Since the primary coagulation tank 4 has a weak binding force of the particles produced in comparison with the conventional process of slow coagulation using an excessive coagulant, the possibility of crushing by stirring is increased, and thus the particle shape and particle size may be deteriorated. There is this. Therefore, in order to improve this, a relatively short residence time and even residence time distribution are induced to suppress vertical agitation in the coagulation tank, and induce a flow without velocity gradient in the flow direction of the fluid, thereby reversible aggregation rather than irreversible aggregation. Induce.

The L / D (coagulation tank length / diameter) of the primary coagulation tank 4 is in the range of 1.5 to 2.0, and the L / D value is larger than that of a general reaction tank to compensate for a relatively short residence time.

In the primary coagulation tank, latex, coagulant and water are supplied through the polymer latex supply line (1), the primary coagulant supply line (2), and the water supply line (3) connected to the lower portion of the coagulation tank, and are installed at the upper side of the primary coagulation tank. Transfer to the upper part of the secondary flocculation tank is performed by the overflow method via the primary flocculation tank overflow line 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.

In the case of the stirrer, the stirrer stage is three stages in consideration of the L / D of 1.5 to 2, and the stirrer used is a radial flow in the absence of a baffle to prevent up and down stirring in the coagulation tank. It is desirable 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. Moreover, it is preferable that the linear velocity of the stirrer is 1.5-3.0 m / sec.

The temperature condition of the primary coagulation tank is preferably a glass transition temperature (Tg) of -40 ℃ to -30 ℃ temperature, in the case of the primary coagulation tank, because the particle size is sensitive to the temperature, the process temperature in the jacket type inside the coagulation tank It is desirable to control the. The residence time in the stirring vessel is preferably in the range of 2 to 5 minutes in terms of particle shape and particle size, and more preferably in the range of 2 to 3 minutes in terms of operational efficiency. 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 first flocculant aqueous solution is used in an amount of 0.5 to 2.5 parts by weight, and is used by diluting with water in order to maintain a uniform mixing concentration in the coagulation tank, and usually, the dilution concentration is preferably in the range of 5 to 10%.

When agglomerating with respect to the polymer latex A, the proper aggregation temperature is about 36 ~ 37 ℃, the flocculant uses calcium salt, the critical aggregation concentration is 2.2 to 2.5 parts by weight based on the polymer in the total solid content of 10% . In the case of agglomeration with respect to the polymer latex B, it is preferable to operate at a high temperature because the rubber content and the glass transition temperature (Tg) are higher than those of the A, and the titration is based on 15% of the total solid content. The flocculation temperature is about 65 ~ 70 ℃, where the flocculant uses magnesium sulfate and the critical aggregation concentration is 0.6 to 0.7 parts by weight based on the polymer.

Stage 3: Secondary Coagulation Tank

The secondary flocculation tank 9 is a step in which an excess flocculant is added to the slurry particles in the creaming state which passed through the primary flocculation tank 4 to become complete flocculation particles. The secondary flocculation slurry, which is completely aggregated particles in the secondary flocculation tank 4, is transferred to the primary aging tank by the overflow method through the secondary flocculation tank overflow line 10.

In addition, the secondary flocculation tank 9 serves as a buffer between the primary flocculation tank 4 and the maturation tank. That is, in the case of polymer latex having a rubber content of 70% or more, when the latex or the non-agglomerate is directly left at a high temperature, a phenomenon occurs that agglomerations between particles are generated due to the impact of heat. In this case, the secondary flocculation tank is the middle of the primary flocculation tank and the aging tank. Step to prevent the aggregation of the particles due to the rapid temperature rise as described above.

The temperature conditions of the secondary flocculation tank 9 vary depending on the characteristics of the latex, and generally range from the primary flocculation tank temperature of + 3 ° C to the primary flocculation tank temperature of + 10 ° C. In terms of thermal efficiency, it is desirable to control the process temperature by direct injection of steam. In addition, the fluid retention time of the secondary flocculation tank 9 is preferably in the range of 10 to 25 minutes.

The primary purpose of the secondary flocculant 8 to be injected into the secondary flocculation tank 9 is to first complete the flocculation of the slurry, which is not completely formed, in the primary flocculation tank 4. However, in the present invention, it is possible to control the thermal decomposition rate on the processing characteristics by changing the amount of the secondary flocculant used in the secondary flocculation tank (9).

In general, many polymerization methods have been tried to control the thermal decomposition rate of PVC impact modifiers. However, the control of pyrolysis rate by the change of polymerization prescription is likely to have unexpected effects on other physical properties, and therefore, even if the pyrolysis rate is controlled by the change of polymerization prescription, it is difficult to adjust the balance between other properties. On the other hand, the technique of controlling the pyrolysis rate in the coagulation process, which is a post-treatment process without changing the polymerization prescription, has the advantage of easily controlling the pyrolysis rate without affecting other physical properties. The control of the thermal decomposition rate proposed in the present invention is made possible by the fact that latex, to which the emulsifier is blended, meets the flocculant and generates internal lubricant.

As a result of detailed experiments, pyrolysis rate can be adjusted according to the amount of secondary flocculant used. In other words, when the secondary coagulant is used in excess of the reference, it reacts with the emulsifier put on the latex and acts as an internal lubricant. The reactant penetrates into the molecules of the polymer material during processing and causes the chains to slide together. This leads to a flow which, in turn, facilitates the extrusion, resulting in a pullup of the pyrolysis rate.

In particular, the attempt to change the thermal decomposition rate by controlling the input of the secondary flocculant is considered to be effective when the flocculation method is a slow flocculation. Although the tendency to decrease is observed, the effect of reducing the rate of thermal decomposition compared to the amount of coagulant used is not so large since excess coagulant is likely to adhere to the particle surface and is subsequently washed out during dehydration.

On the other hand, in the case of slow flocculation, the emulsifier added to latex reacts with the metal ions of the flocculant to generate internal lubricants, so that it is less washed off by water. In addition, the input of the flocculant is divided into two and a half, and the role of the flocculant is different at each injection point, so that the amount of flocculant used for flocculation and processing characteristics can be clearly controlled compared to the existing process. have.

In the case of the stirrer used in the secondary flocculation tank 9, since the particle shape does not react sensitively to the stirring force of the stirrer as compared with the primary flocculation tank 4, the stirrer is pitched paddle type or flat. You can use a flat paddle.

If the rubber content is sensitive to heat, such as the polymer latex A, it is operated at 4 to 5 ° C. or more (40 to 45 ° C.) compared to the primary coagulation tank, and the polymer latex B having a rubber content of 50% is at a temperature. Because it is not very sensitive, operate at about 10 ℃ or more (75 ~ 80 ℃).

4th stage: primary aging tank

The primary aging tank 11 is a step of strengthening the hardness of the aggregated particles passed through the primary and secondary flocculation tanks, and this step is 60 to 90 at the secondary flocculation tank temperature +5 ℃ to the secondary flocculation tank temperature +20 ℃ Run for a minute to allow interchain penetration between polymer chains to form a solid particle.

In the aging tank, since the slurry particle shape 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 a smooth flow in the aging tank it is preferable to use a pitched paddle type (Pitched Paddle type) is installed.

The primary aging tank 11 searches for appropriate conditions of the shape and particle size of the particles made in the secondary flocculation tank and keeps them in subsequent steps.

In the case of the polymer latex A, the temperature conditions of the primary aging tank (11) is 60 ~ 65 ℃, when the temperature exceeds 65 ℃ agglomeration of particles is found, if less than 60 ℃ secondary aging tank (14) There is a problem that the particles are aggregated in. In the case of the polymer latex B, the temperature condition of the primary aging tank is preferably 80 ~ 85 ℃.

Stage 5: Second Aging Tank

The secondary aging tank 14 is a step for strengthening the hardness of the aggregated particles similar to the primary aging tank 11, the same as the primary aging tank primary aging tank temperature +10 ℃ to primary aging tank temperature +20 It is preferable to operate at 60 degreeC for 60 to 90 minutes.

In the case of the polymer latex A, the secondary aging tank 14 has a temperature condition of 85 to 90 ° C., in the case of 90 ° C. or more, the particles are enlarged by an impact due to high temperature. Reduced hardness may cause problems in the dehydration process. In addition, in the case of the polymer latex B, it is preferable that the secondary aging bath temperature conditions are 93-98 degreeC.

Thus, the polymer latex resin powder produced through the two-stage flocculation tank and the maturation tank, respectively, is 70-400 ㎛ 85-97 weight, unlike the conventional commercial polymer resin whose particle diameter is widely distributed over the range of 74-841 ㎛ It is added, the fine powder of less than 70㎛ fine powder and more than 400㎛ fine each 10% by weight or less and at the same time excellent in the apparent specific gravity and the caking characteristics.

Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, the scope of the present invention is not limited to an Example.

Example 1

In the manufacturing line of FIG. 1, the polymer latex (A) having a solid content of 40% and 0.3 parts by weight of sodium lauryl sulfate was added at a flow rate of 132 L / hr to improve the stability of the latex. 11.7 L / hr of diluted calcium salt flocculant (2.2 parts by weight of polymer resin) and 263 L / hr of water are simultaneously supplied to the lower part of the primary flocculation tank, and the residence time and the process temperature of the primary flocculation tank are 2 minutes 30 seconds / After inducing aggregation by adjusting to 37 degreeC, it transferred to the secondary flocculation tank by the overflow system. At this time, the secondary calcium salt flocculant 90 L / hr was added as a secondary flocculant in the secondary flocculation tank, the residence time was adjusted to 10 minutes and the process temperature was adjusted to 42 ℃. After the agglomerated slurry is transferred to the top of the aging tank, the primary / secondary aging tank was maintained for 30 minutes at the aging temperature of 60 ℃ / 90 ℃, respectively, to achieve sufficient aging. After aging, the polymer latex resin powder was transferred to a storage tank, 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.

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 secondary calcium salt flocculant is added in 45 L / hr in Example 1 is shown in Table 1.

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 secondary calcium salt flocculant was added in Example 1 was added to 60 L / hr.

Comparative 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 secondary calcium salt flocculant was added in Example 1 was added to 120 L / hr.

[Comparative Example 4]

Particle size distribution and physical properties of the polymer latex resin powder obtained by the same method as Example 1 except that sodium lauryl sulfate (sodium lauryl sulfate) for improving the latex stabilization in Example 1 is not added It is shown in Table 1 below.

division Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Polymer latex A A A A A Particle size distribution 400 ㎛ or more One 0 0 2 3 300 to 400 μm 11 10 7 15 11 70 to 300 μm 85 85 88 80 81 Less than 70 ㎛ 3 5 5 3 5 Apparent specific gravity 0.46 0.46 0.46 0.45 0.40 Emulsifier 0.3 0.3 0.3 0.3 No addition Secondary flocculant content (parts by weight) 6 3 4 8 6 Fusion Time (sec) 89 101 96 88 98 Residual metal (ppm) 1450 920 1130 1680 880

Through Table 1, the polymer latex resin powder prepared in Example 1 was 85 parts by weight when the particle diameter is 70 ~ 400 ㎛ as well as the thermal decomposition rate was 89 seconds as a result of evaluation of the processing characteristics. In Comparative Examples 1 and 2 in which the content of the secondary flocculant is adjusted, the amount of residual metal in the powder increases as the secondary flocculant content increases, and the thermal decomposition rate decreases linearly. However, when 8 parts by weight of the secondary coagulant of Comparative Example 3 was added, it can be confirmed that the reduction of the existing thermal decomposition rate is greatly reduced and there is no significant difference from 6 parts by weight, which is similar in the case of 10 parts by weight. In addition, when the emulsifier to be added to the latex in the Example (Comparative Example 4), even if a lot of secondary flocculant is added, the reduction of the thermal decomposition rate did not occur. Therefore, it can be seen that the thermal decomposition rate can be controlled when the coagulant and the emulsifier react in an appropriate ratio in the thermal decomposition rate control by controlling the amount of residual metal.

Example 2

Polymeric latex (B) with 42% solids concentration and 0.3 parts by weight of sodium dioctylsulfosuccinate added to improve the stability of latex 7.1 L of magnesium sulfate diluted to 5% at a flow rate of 121 L / hr / hr and 211 L / hr of water are fed to the bottom of the primary coagulation tank at the same time, the residence time of the primary coagulation tank and the process temperature are adjusted to 3 minutes / 60 ℃ respectively to induce coagulation, and then overflow into the secondary coagulation tank Transported by way. At this time, 40.6 L / hr of secondary magnesium sulfate was added to the secondary flocculation tank, the residence time was adjusted to 10 minutes, and the amount of steam was adjusted so that the process temperature was 70 ℃. After the agglomerated slurry is transferred to the top of the aging tank, the primary / secondary aging tank was maintained for 30 minutes at a aging temperature of 80 ℃ / 93 ℃, respectively, to achieve sufficient aging. After aging, the polymer latex resin powder was transferred to a storage tank, and the particle size distribution and physical properties of the polymer latex resin powder obtained through the above process are shown in Table 2 below.

[Comparative Example 5]

The particle size distribution and physical properties of the polymer latex resin powder obtained in the same manner as in Example 2 except that the secondary magnesium sulfate coagulant was added in Example 2, 20.3 L / hr is shown in Table 2 below.

Comparative Example 6

The particle size distribution and physical properties of the polymer latex resin powder obtained in the same manner as in Example 2 except that the secondary magnesium sulfate coagulant was added in Example 2, 60.9 L / hr is shown in Table 2.

Comparative Example 7

Particle size distribution and physical properties of the polymer latex resin powder obtained in the same manner as in Example 2, except that sodium dioctylsulfosuccinate is not added to improve latex stabilization in Example 2 It is shown in Table 2 below.

division Example 2 Comparative Example 5 Comparative Example 6 Comparative Example 7 Polymer latex B B B B Particle size distribution (% by weight) 400 ㎛ or more 3 0 2 3 300 to 400 μm 9 7 5 9 70 to 300 μm 88 88 90 83 Less than 70 ㎛ 0 5 3 5 Apparent specific gravity (gr / cc) 0.43 0.44 0.43 0.40 Emulsifier Content (parts by weight) 0.3 0.3 0.3 0 Secondary flocculant content (parts by weight) 4 2 6 4 Fusion Time (sec) 94 12 93 105

As a result of Table 2, even in the case of polymer latex B, as the content of the secondary flocculant is increased, the thermal decomposition rate is not significantly affected, but the thermal decomposition rate is decreased, but pyrolysis is not performed in the latex. The speed reduction is greatly reduced.

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, and fine powder of less than 70 μm and powder of more than 400 μm are each 10 parts by weight or less. At the same time, the apparent specific gravity and the caking properties of the powder are excellent, and in particular, the processing characteristics can be controlled only by changing the conditions during the coagulation process, not by changing the prescription of the polymerization phase.

While the invention has been described in detail above with reference to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope and spirit of the invention, and such modifications and variations fall within the scope of the appended claims. It is also natural.

Claims (8)

(a) adding 0.3 to 0.4 parts by weight of an emulsifier to 100 parts by weight of the polymer latex into the polymer latex storage tank; (b) continuously supplying polymer latex, primary flocculant and water to the primary flocculation tank; (c) In the primary flocculation tank, the mixture is first agglomerated by holding the mixture at a glass transition temperature (Tg) -40 ° C to a glass transition temperature (Tg) -30 ° C for 2 to 5 minutes, and the prepared primary flocculation Transferring the slurry to a secondary flocculation tank; (d) In the secondary flocculation tank, the secondary flocculant is added to the primary flocculation slurry and the secondary flocculation tank is kept at the temperature of the primary flocculation tank temperature at + 3 ° C to the primary flocculation tank temperature at + 10 ° C for 10 to 25 minutes. After coagulation, transferring the prepared secondary coagulation slurry to a primary aging tank; (e) In the first aging tank, the secondary flocculation slurry is first aged by staying at the temperature of the secondary flocculation tank temperature at + 5 ° C. to the secondary flocculation tank temperature at + 20 ° C. for 60 to 90 minutes, and the prepared primary Transferring the aged slurry to the secondary aging tank; And (f) preparing a polymer latex resin powder by holding the first aging slurry in a second aging tank for 60 to 90 minutes at a temperature of a first aging tank temperature of + 10 ° C. to a temperature of 20 ° C .; Method for producing a polymer latex resin powder comprising a. The method of claim 1, wherein the primary coagulant of step (b) and the secondary coagulant of step (c) are at least one member selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, sulfate, calcium salt and magnesium sulfate. Method for producing a polymer latex resin powder. The method for preparing a polymer latex resin powder according to claim 1, wherein the particle size of the polymer latex of step (b) is 0.05 to 0.4 µm. The method of claim 1, wherein the primary coagulant of step (b) is diluted to a concentration of 5 to 10% in water and used at 0.5 to 2.5 parts by weight based on the polymer latex. The method for producing a polymer latex resin powder according to claim 1, wherein the primary agglomerated slurry of step (c) is creamy. The method of claim 1, wherein the secondary coagulant of step (d) is used in an amount of 3 to 8 parts by weight based on the polymer latex. The method for producing a polymer latex resin powder according to claim 1, wherein the powder having a size of 70 to 400 µm in the polymer latex resin powder is 85 to 97 parts by weight based on the total weight of the polymer latex resin powder. A polymer latex resin powder prepared by the method of claim 1.