KR19980039854A - Manufacturing method of thermoplastic resin powder - Google Patents

Abstract

The present invention relates to a method for producing a thermoplastic resin powder, and more particularly, a mixed slurry of graft copolymer latex and a vinyl copolymer latex is agglomerated with an aqueous solution of a flocculant to obtain a flocculated slurry, and the flocculated slurry. The present invention relates to a method for producing a thermoplastic resin powder having a uniform particle size distribution by separating and recovering only the aggregated particles having a specific particle size contained therein and coagulating the remaining fine aggregate slurry again.

Description

Manufacturing method of thermoplastic resin powder

The present invention relates to a method for producing a thermoplastic resin powder, and more particularly, a mixed slurry of graft copolymer latex and a vinyl copolymer latex is agglomerated with an aqueous solution of a flocculant to obtain a flocculated slurry, and the flocculated slurry. The present invention relates to a method for producing a thermoplastic resin powder having a uniform particle size distribution by separating and recovering only the aggregated particles having a specific particle size contained therein and coagulating the remaining fine aggregate slurry again.

In the coagulation process of a common polymer latex, a coagulant is introduced at a concentration of a latex controlled by a certain amount of pure water continuously in a series of coagulation facilities maintained at a high temperature to coagulate in a powder form. However, the polymer latex powder prepared by such agglomeration process is generally known. In the case of general extrusion powder having a glass transition temperature (Tg) of 80 to 90 ° C., since the fine powder is less than 100 μm and the particle size distribution is constant, There is no problem with secondary processing or quality. However, in the case of heat-resistant extrusion powders having a glass transition temperature (Tg) of 100 to 130 ° C., there are many fine powders of 100 μm or less, which makes it difficult to insert into the extruder during the secondary processing of the powder, that is, the extrusion process of the thermoplastic resin powder. As the residence speed in the extruder is different according to the particle size difference of the powder and the fine powder stays in the extruder for a long time, deterioration of the working environment due to scattering of the fine powder and dehydration of the water-containing powder along with deterioration of color and quality of the resin And when the fine powder is discharged with the washing liquid at the time of washing, the loss amount of the fine powder is excessive.

In order to suppress the formation of fine powder generated during the flocculation process of the polymer latex, a method of raising the flocculation temperature or increasing the content of solids may be applied. However, when such a method is applied, the flocculation tank is formed due to excessive generation of large particle size. It is not preferable because the outlet is clogged or the pipe is clogged during the transfer, so the downtime of the process is high.

In the present invention, in the flocculation of polymer latex having excellent heat resistance prepared by emulsion polymerization, the polymer latex is agglomerated under specific conditions with a flocculant in an aqueous solution to prepare a flocculation slurry, and 75 to 150 µm or more contained in the flocculation slurry. The present invention has been completed by preparing a heat-resistant compression thermoplastic resin powder having a uniform particle size distribution through a continuous agglomeration process in which only aggregated particles are separated and recovered, and the fine aggregate slurry is aggregated again.

The present invention provides a method for producing a thermoplastic resin powder for heat-resistant compression to solve the problem of deterioration of quality, contamination of working environment, and lowering of productivity due to general coagulation process due to uniform particle size distribution. The purpose is.

1 is a view schematically showing the aggregation process of the polymer latex according to the present invention.

Explanation of symbols for main parts of the drawings

1a, 1b: flocculation tank 2: vibrating body

3: dehydration tank 4: flocculation slurry storage tank

5: mixer

In the method for producing a thermoplastic resin powder by agglomerating the polymer latex, uniform particle size distribution,

Graft copolymer latex containing rubbery and vinyl polymer latex containing α-methylstyrene as a main component are mixed and the coagulant in aqueous solution is continuously introduced into a high temperature coagulation bath and coagulated to obtain a coagulation slurry. Thermoplastic resin powder having a uniform particle size distribution consisting of a continuous flocculation process in which only flocculation particles of 75 to 150 µm or more contained in the flocculation slurry are separated and recovered, but the fine flocculation slurry of 75 to 150 µm or less is reintroduced into the flocculation tank. It characterized by the manufacturing method of the.

Referring to the present invention in more detail as follows.

The present invention relates to a method for producing a thermoplastic resin powder having a uniform particle size distribution by agglomerating a polymer latex prepared by emulsion polymerization and having excellent heat resistance.

The polymer latex used in the flocculation process of the present invention can be used as long as it can be flocculated as prepared by emulsion polymerization. Preferably, a graft copolymer latex containing a rubbery material and a mixed polymer latex containing a vinyl copolymer latex containing α-methylstyrene as a main component are used. When the graft copolymer latex alone is used, the coagulation is well performed, but there are many problems with large particle powder, and when the vinyl latex is used alone, a large amount of fine powder is generated, but in the present invention, such a problem is caused by using a mixed polymer latex. Completely solved.

In using the mixed polymer latex, it is particularly preferred to use 20 to 60% by weight of the graft copolymer latex and 40 to 80% by weight of the vinyl copolymer latex. When the content of the graft copolymer contained in the mixed polymer latex is less than 20% by weight, the impact strength of the thermoplastic resin powder is lowered, and when the content of the graft copolymer is greater than 60% by weight, the workability is inferior. And if the content of the vinyl copolymer latex contained in the mixed polymer latex is less than 40% by weight, the heat deformation temperature of the thermoplastic resin powder is lowered, if it exceeds 80% by weight there is a problem that workability is lowered.

The graft copolymer latex contained in the mixed polymer latex is composed of a butadiene monomer containing a double bond and a vinyl monomer, and α-methylstyrene, styrene, acrylonitrile and the like may be used as the vinyl monomer. The graft copolymer latex is to maintain the rubber content of 20 to 70% by weight, but if the rubber content is less than 20% by weight, there is a problem that the impact strength of the prepared thermoplastic resin powder is lowered. There is a problem of deterioration.

In addition, the vinyl copolymer latex contained in the mixed polymer latex is composed mainly of the vinyl monomer so that 30-80 wt% of α-methylstyrene is contained. If the content of α-methylstyrene is less than 30% by weight, there is a problem that the heat resistance is lowered, and if it exceeds 80% by weight, the heat resistance is excellent but impact strength and workability are lowered.

In the present invention, one or two or more selected from organic acids, inorganic acids and metal salts thereof are used as flocculants for flocculating the polymer latex. Specific examples of the flocculant include organic and inorganic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and acetic acid, and magnesium sulfate, magnesium chloride, ammonium chloride, aluminum sulfate, and aluminum hydroxide.

In addition, the flocculant is preferably used 2 to 10 parts by weight based on 100 parts by weight of the polymer latex, if the amount of the flocculant is less than 2 parts by weight, the cohesiveness of the latex is reduced, a large amount of fine powder is generated, exceeding 10 parts by weight The cohesiveness is excellent, but due to the residual coagulant.

Referring to the aggregation process of the thermoplastic resin powder according to the present invention with reference to Figure 1 attached in more detail as follows.

Graft copolymer latex and vinyl copolymer latex are passed through a mixer (5) to the first aggregation tank (1a) having an internal temperature of 90 to 95 ° C. and a rotation speed of the stirrer is 40 to 200 rpm. The flocculant is added continuously through the other inlet. As another inlet, pure water is continuously added to adjust the solid content of the mixed polymer latex to 10 to 50% by weight, thereby initiating the aggregation of the mixed polymer latex.

At this time, if the stirring speed of the stirrer installed in the first aggregation tank 1a is less than 40 rpm, the stirring force is weak, so that a large amount of agglomeration slurry is generated, and a large amount of scale is formed on the wall of the agglomeration tank, so that continuous agglomeration is difficult. If the stirring speed exceeds 200 rpm, a large amount of fine flocculation slurry is generated, the slurry loss is large, the yield is lowered, and there is a problem in that dust generation is increased after the dehydration and drying process. If the solid content of the polymer latex is less than 10% by weight, the size of the aggregated particles is reduced and the content of the fine aggregated particles is increased, which is inefficient. There is a problem that moisture is not easily removed in the process.

When the flocculation process is completed, the flocculation slurry is transferred to another second flocculation tank 1b having an internal temperature of 120 to 130 ° C. and aged until the slurry particles are hardened.

The aged aggregate slurry is transferred to the vibrating body 2 and separated. It is preferable to adjust 90 to 95% by weight of the aged agglomeration slurry to have a particle size distribution in the range of 75 to 150 μm in terms of production yield and reaggregation effect. Such slurry particle size adjustment is possible by adjusting the amount of coagulant and the rotation speed of the stirrer.

The vibrating body 2 is divided into two stages, and a 30-100 mesh sieve is installed at the upper end, and an 80-200 mesh sieve is installed at the lower end. At the upper end of the vibrating body 2, fine agglomerated slurries having a particle diameter of 75 to 150 μm are transferred to the microslurry reservoir 4, and the agglomerated particles having a particle diameter of 75 to 150 μm or more are transferred to the bottom of the vibrating body 2.

At this time, if the mesh size of the sieve provided at the upper end of the vibrating body 2 is less than 30 mesh, there is a problem that the vibrating body installed at the lower end has to be large, and if larger than 100 mesh, the separation efficiency of the large particles and the fine particles is deteriorated.

Water is added to agglomerated particles of 75 to 150 μm or more separated from the lower end of the vibrator 2 to adjust the slurry concentration to 10 to 40 wt%, and then transferred to a dehydration tank (D-1) to dehydrate and dry. At this time, when the concentration of the aggregated particles is less than 10% by weight, it is not easy to transfer to the next process, and when the concentration exceeds 40% by weight, the drying efficiency decreases due to the high water content.

On the other hand, the fine agglomerated slurry having a particle diameter of less than 75 ~ 150 ㎛ separated from the upper end of the vibrating body 2 is sent to the microslurry storage tank 4 and stored, and then re-introduced into the first agglomeration tank 1a to undergo a coagulation process again. . In this case, a mixed polymer latex is newly introduced into the first aggregation tank 1a together with the fine flocculation slurry. The fine agglomeration slurry may be directly added to the first agglomeration tank 1a, but rather, the fine agglomeration slurry is first introduced into the mixer 5, mixed with newly introduced polymer latex, and then added to the first agglomeration tank 1a to agglomerate. More efficient. As the mixer 5 which can be used in the present invention, it is preferable to use a line mixer which is generally used.

On the other hand, the fine flocculation slurry re-introduced into the first aggregation tank (1a) and the newly added mixed polymer latex is preferably maintained 5 to 40% by weight: 60 to 95% by weight. If the amount of fine coagulation slurry to be re-injected is less than 5% by weight, the coagulation is easy, but it is contrary to the object of the present invention to reuse the fine coagulation slurry, and if the amount of fine coagulation slurry exceeds 40% by weight, it is not easy to reaggregate. There is no problem.

As a result, when the reaggregation process is completed, the coagulation slurry is aged by another second coagulation, and the aged coagulation slurry is transferred to the vibrating body 2 to separate and recover only coagulated particles transferred to the tank 1b of 75 to 150 µm or more. The remaining fine flocculation slurry is subjected to the reaggregation process continuously.

Therefore, the method for producing a thermoplastic resin powder according to the present invention does not require any special apparatus for preparing a solidified thermoplastic resin by adding mixed polymer latex into a coagulation bath, and also strives to prevent the formation of fine particles at the initial aggregation. Unlike conventionally known agglomeration treatment methods, the produced powder is simply mechanically separated and agglomerated as a newly added latex, thereby making it possible to manufacture a powder having a uniform particle size, thereby simplifying the control of the manufacturing process and reducing the occurrence of fine particles. Production of the resin powder is easy.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Examples 1-5 and Comparative Examples 1-5

The first agglomeration tank 1a and the second agglomeration tank 1b are connected in series, and other coagulation conditions are shown in Table 1 below.

A certain amount of pure water was added to the first agglomeration tank 1a according to the content of the latex solid content, and then adjusted to an internal temperature of 95 ° C. using steam. The graft copolymer latex and the vinyl copolymer latex were continuously introduced into the first aggregation tank 1a through the mixer 5 while keeping the stirring speed constant. At the same time, a 20% magnesium sulfate (MgSO ₄ ) aqueous solution was directly added to the first aggregation tank 1a continuously through another inlet as a coagulant.

The flocculation slurry in which the flocculation was completed in the first flocculation tank 1a was transferred to the second flocculation tank 1b having an internal temperature of 130 ° C. and aged for 1 hour.

The flocculation slurry discharged from the second flocculation tank 1b was transferred to the vibrating body 2 to separate the flocculation particles and the fine flocculation slurry from 75 to 150 μm or more. The vibrating body 2 is comprised in two stages, 50 mesh sieve is provided in the upper end, and 120 mesh sieve is provided in the lower end.

Thermoplastic resin powder of the present invention by adding water to agglomerated particles of 75 ~ 150 ㎛ or more separated from the vibrating body (2) to adjust the slurry concentration to 25% by weight, and then transferred to a dehydration tank (3) to dehydrate and dry. Got.

In addition, the fine coagulation slurry of less than 75 ~ 150 ㎛ separated from the vibrating body 2 is transferred to the cohesion slurry storage tank 4, and then the polymer graft copolymer latex and vinyl newly introduced by passing through the mixer (5) The mixture was sufficiently mixed with the latex copolymer and introduced into the first aggregation tank 1a to perform the aggregation process as described above. The input ratios of the fine flocculation slurry and the mixed polymer latex introduced into the first aggregation tank 1a through the mixer 5 are shown in Table 2 below.

In addition, the thermoplastic resin powder prepared by the agglomeration process as described above measured physical properties and particle size distribution by the following method, the results are shown in Table 2 below.

division Mixed polymer latex First coagulation stirrer (rpm) Flocculant Graft Copolymer Latex ⁽¹⁾ Vinyl Copolymer Latex ⁽²⁾ Solid content (% by weight) Kinds Input amount ⁽⁴⁾ (by weight) Input amount (% by weight) Rubber content (%) Input amount (% by weight) α-MS ⁽³⁾ Content (%) Example 1 40 45 60 60 10 120 MgSO ₄ 4 Example 2 37 50 63 65 20 125 H ₂ SO ₄ 4 Example 3 34 55 66 70 30 120 MgSO ₄ 6 Example 4 30 60 70 75 40 130 H ₃ PO ₄ 6 Example 5 25 65 75 75 50 140 MgSO ₄ 8 Comparative Example 1 10 50 90 20 20 30 H ₂ SO ₄ 8 Comparative Example 2 15 55 85 30 25 250 H ₃ PO ₄ 8 Comparative Example 3 40 45 60 60 10 120 H ₂ SO ₄ 9 Comparative Example 4 37 50 63 65 20 125 MgCl ₂ 9 Comparative Example 5 30 60 70 75 40 130 MgSO ₄ 10 Note) (1) Graft copolymer latex: 50% by weight of butadiene, 35% by weight of styrene, 15% by weight of acrylonitrile is graft copolymerized. : 70% by weight of α-methylstyrene and 30% by weight of acrylonitrile are graft copolymerized. (Miwon Emulsification Co., Ltd.) (3) α-MS: (4) Input of flocculant to 100 parts by weight of mixed polymer latex

division Home Water properties ^{a) B)} (Mesh on%) Mixed Polymer Latex (wt%) Fine flocculation slurry (% by weight) Heat resistance (℃) Impact strength (kgcm / cm) Fluidity (g / min) 50 100 200 Pass Example 1 95 5 98 20 20 30 80 98 2 Example 2 93 7 99 18 18 28 80 98 2 Example 3 90 10 105 16 15 26 75 97 3 Example 4 85 15 107 16 13 24 75 97 3 Example 5 70 30 110 13 12 20 70 96 4 Comparative Example 1 60 40 85 10 20 35 80 93 7 Comparative Example 2 50 50 85 11 18 36 80 80 20 Comparative Example 3 40 60 98 20 19 20 60 70 30 Comparative Example 4 30 70 98 18 19 20 55 65 35 Comparative Example 5 20 80 106 12 14 15 50 60 40 A) Property measurement method and heat resistance: ASTM D648 / 6.4 mm x 18.6 kg / cm2 Conditions and impact strength: ASTM D256 / specimen thickness 6.4 mm Notched and fluidity: ASTM D1238 / 200 ° C x 21.6 kg Load b) Particle size distribution methodMeasure the particle size distribution in a vibrating body composed of 50/100/200 mesh manufactured according to ASTM standard, and after weighing 200g of the collected powder for 3 minutes in the vibrating body, Measured and converted to weight% 50 Mesh: 360 μm, 100 mesh: 150 μm, 200 mesh: 75 μm

The thermoplastic resin powder prepared by the flocculation process of the polymer latex according to the present invention has excellent heat resistance and powder particles having a particle diameter of 75 to 150 μm or more are 95 wt% or more, so that the extrudability of the powder in the extruder is improved and the color of the resin is increased. This improved and the loss of fine powder was greatly reduced. Therefore, the thermoplastic resin powder prepared in the present invention is particularly useful for producing heat resistant thermoplastic resins having improved color of the resin.

Claims (11)

In the method for producing a thermoplastic resin powder by agglomerating the polymer latex, uniform particle size distribution, Graft copolymer latex containing rubbery and vinyl polymer latex containing α-methylstyrene as a main component are mixed and the coagulant in aqueous solution is continuously introduced into a high temperature coagulation bath and coagulated to obtain a coagulation slurry. Only 75-150 μm or more of the aggregated particles contained in the coagulation slurry are recovered and separated, but the fine coagulation slurry of 75-150 μm or less is made into a continuous coagulation process in which the coagulation tank is reintroduced into the coagulation bath to coagulate. A process for preparing a thermoplastic resin powder. The particle size distribution of claim 1, wherein the filtration process is performed in a vibrating body having a 30 to 100 mesh sieve at the upper end and an 80 to 200 mesh sieve at the lower end. Method for producing a thermoplastic resin powder. The method for producing a thermoplastic resin powder having a uniform particle size distribution according to claim 1 or 2, wherein the fine flocculation slurry of less than 75 to 150 µm separated during the filtration process is re-agulated to the flocculation tank. . The method of claim 3, wherein the fine flocculation slurry is re-injected into the flocculation tank at a ratio of 5 to 40 wt% based on 60 to 95 wt% of the mixed polymer latex. The method of claim 1, wherein the mixed polymer latex is a mixture of 20 to 60% by weight of graft copolymer latex containing rubber and 40 to 80% by weight of vinyl copolymer latex containing α-methylstyrene as a main component. A method for producing a thermoplastic resin powder having a uniform particle size distribution. The particle size of claim 1 or 5, wherein the graft copolymer latex has a rubber content of 20 to 70%, and the vinyl copolymer latex has a content of α-methylstyrene of 30 to 80%. Method for producing a thermoplastic resin powder with a uniform distribution. 6. The method of claim 1 or 5, wherein the mixed polymer latex has a solid content of 10 to 50% by weight. The method for producing a thermoplastic resin powder having a uniform particle size distribution according to claim 1, wherein said flocculant is one or two or more selected from organic acids, inorganic acids and metal salts thereof. The method of claim 1, wherein pure water is added to the aggregated particles of 75 ~ 150 ㎛ or more by adjusting the solid content concentration to 10 to 40% by weight of the thermoplastic resin powder with a uniform particle size distribution, characterized in that dehydration and drying Manufacturing method. The method for producing a thermoplastic resin powder having a uniform particle size distribution according to claim 1, wherein the agglomeration tank is provided with a stirrer and the reactant is stirred at a stirring speed of 40 to 200 rpm. The method of claim 1, wherein 90 to 95% by weight of the thermoplastic resin powder has a particle size distribution in the range of 75 to 150 μm.