Title of Invention: Graft copolymer and method for preparing same
technical field
[One]
Cross-Citation with Related Applications
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0152004 dated November 25, 2019, and all contents disclosed in the literature of the Korean patent application are incorporated as a part of this specification.
[3]
technical field
[4]
The present invention relates to a graft copolymer, and the graft copolymer of the present invention has less agglomeration between particles compared to the dry powder type graft copolymer, so it is easy to transport, and there is little change in product quality over a long period of time. There are advantages.
background
[5]
Graft copolymers, specific examples of which are ABS-based copolymers such as acrylonitrile-butadiene-styrene, or ASA-based copolymers such as acrylate-styrene-acrylonitrile Because of its relatively good physical properties such as rigidity, chemical resistance, and impact resistance, as well as formability and gloss, it is widely used as housing or interior and exterior materials for various products such as electric parts, electronic parts, office equipment, and automobile parts.
[6]
In general, graft copolymers are graft copolymerized with styrene and acrylonitrile in rubber latex such as polybutadiene or poly(butyl acrylate) by emulsion polymerization to improve impact resistance, and then, this is a styrene-acrylonitrile copolymer. It is prepared by kneading with a thermoplastic resin such as a SAN-based resin such as polystyrene and polymethyl methacrylate, and the like to obtain a resin composition. In this manufacturing process, the graft copolymer is generally prepared in the form of dry powder (DP) before kneading with the thermoplastic resin, and the graft copolymer in the dry powder state is also kneaded with the thermoplastic resin immediately after manufacturing , it is sometimes kneaded with the thermoplastic resin through a separate kneading process after a certain time has elapsed from the time of manufacture. Therefore, the ease of storage of the graft copolymer itself or the characteristics of the quality of the graft copolymer stored for a long period of time are major factors to be considered when preparing the graft copolymer.
[7]
On the other hand, the graft copolymer in dry powder form has the advantage of being easy to manufacture, but if it is not immediately kneaded with a thermoplastic resin, the powder particles agglomerate and are not easily separated during long-term storage. can occur Therefore, there is a need for research to improve the storage easiness of the prepared graft copolymer and to minimize the change in quality over time.
[8]
[9]
Prior art literature
[10]
(Patent Document 1) KR 10-2019-0059037 A
[11]
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[12]
The present invention is to solve the problems of the prior art, and to provide a graft copolymer in which agglomeration between particles during storage is minimized, and change in quality over time is minimized even in long-term storage.
means of solving the problem
[13]
In order to solve the above problems, the present invention includes at least one of a unit derived from a conjugated diene-based monomer and a unit derived from an acrylate-based monomer, and at least one of a unit derived from a vinyl cyanide-based monomer and a unit derived from an aromatic vinyl-based monomer, and bulk density Provided is a graft copolymer having a value of 450 kg/m 3 to 700 kg/m 3 .
[14]
In addition, the present invention provides a pellet formed of the above graft copolymer.
[15]
In addition, the present invention polymerizes at least one of a vinyl cyanide monomer and an aromatic vinylic monomer to a conjugated diene-based polymer or an acrylate-based polymer to obtain a reactant including a graft copolymer (S1) and an extruder. It provides a method for producing a graft copolymer comprising the step (S2) of molding the reactant in the form of a pellet.
Effects of the Invention
[16]
The graft copolymer provided by the present invention has excellent storage easiness, so there is less aggregation between particles even when stored for a long period of time, the change in quality over time is minimized, and the amount of residual monomer is also low, so that it is applied to a thermoplastic resin composition, etc. can keep it
Brief description of the drawing
[17]
1 shows an extruder having a vent unit that can be used for preparing the graft copolymer of the present invention.
[18]
Figure 2 shows an extruder having a side slot that can be used to prepare the graft copolymer of the present invention.
[19]
3 is a view showing the results of the caking generation test of the pellets prepared in Examples of the present invention and the dry powders prepared in Comparative Examples.
Modes for carrying out the invention
[20]
Hereinafter, the present invention will be described in more detail.
[21]
The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of ​​the present invention.
[22]
[23]
graft copolymer
[24]
Graft copolymers such as acrylonitrile-butadiene-styrene copolymer or acrylate-styrene-acrylonitrile widely used in various industrial fields include vinyl cyanide monomers and After mixing the aromatic vinyl-based monomer, it is prepared by graft polymerization.
[25]
Polymerization reaction in this manufacturing process can be carried out through various methods, such as emulsion polymerization, solution polymerization, or bulk polymerization, but emulsion polymerization is preferred in terms of uniform reaction, easy molecular weight control, and high polymerization rate. do.
[26]
On the other hand, when a graft copolymer is prepared through an emulsion polymerization method, the reaction product obtained after the reaction is completed is a dispersion medium such as water, an emulsifier or surfactant, etc. is included, and the graft copolymer is present in a dispersed form in the reactant. Therefore, in order to use the polymerized graft copolymer as a product afterward, it is necessary to remove the dispersion medium and impurities, and to aggregate the dispersed graft copolymer. Accordingly, in the conventional graft copolymer manufacturing process, after polymerization, The processes of agglomeration, de-dispersing medium (dehydration) and drying are carried out.
[27]
In the case of such aggregation, de-dispersion medium and drying process, most of the dispersion medium is removed, and as the graft copolymer is dried in an agglomerated state, the final product is prepared in the form of dry powder. . The graft copolymer in dry powder form is then commercialized as needed, or mixed with other thermoplastic resins to be used as a thermoplastic resin composition.
[28]
However, when the graft copolymer has such a dry powder form, agglomeration between powder particles may occur during storage or transportation before subsequent use. In particular, when storing or transporting a large amount of dry powder, the powder at the bottom may form a lump like a cake due to the pressure of the powder located at the top, and this caking phenomenon makes it cumbersome to use the dry powder afterwards. Rather, it causes a problem of lowering the quality of the dry powder particles.
[29]
In order to solve this problem, the inventors of the present invention do not completely dehydrate the reactant prepared through the existing emulsion polymerization method, but adjust the moisture content to a specific range and then prepare it in the form of a pellet through an extruder. The graft copolymer of the present invention that can solve the problems of the prior art was invented.
[30]
[31]
Specifically, the present invention provides a graft copolymer having a bulk density of 450 kg/m 3 to 700 kg/m 3 . For example, the graft copolymer provided by the present invention is 450 kg/m 3 or more, 500 kg/m 3 or more, 530 kg/m 3 or more, or 550 kg/m 3 or more, 700 kg/m 3 or less, 650 kg/m 3 or less, 600 kg/ It has a bulk density of m 3 or less or 570 kg/m 3 or less, whereas the conventional graft copolymer prepared in dry powder form has a bulk density of less than 450 kg/m 3 , or less than 400 kg/m 3 . The graft copolymer of the present invention is characterized in that it exhibits a larger bulk density compared to the dry powder form because a large amount of the graft copolymer has a physically interconnected form between particles.
[32]
[33]
In the present invention, the graft copolymer specifically includes at least one of a unit derived from a conjugated diene-based monomer and a unit derived from an acrylate-based monomer, and at least one of a unit derived from a vinyl cyanide-based monomer and a unit derived from an aromatic vinyl-based monomer.
[34]
More specifically, the graft copolymer may include a unit derived from a conjugated diene-based monomer, a unit derived from a vinyl cyanide-based monomer, and a unit derived from an aromatic vinyl monomer, or an acrylate-based monomer-derived unit, vinyl It may include a unit derived from a cyan-based monomer and a unit derived from an aromatic vinyl-based monomer.
[35]
In particular, when the graft copolymer includes a unit derived from a conjugated diene-based monomer, a unit derived from a vinyl cyan-based monomer, and a unit derived from an aromatic vinyl-based monomer, the graft copolymer is added to the conjugated diene-based polymer with vinyl cyanide. The type monomer and the aromatic vinyl-based monomer may be graft-polymerized. In addition, when the graft copolymer includes an acrylate-based monomer-derived unit, a vinyl cyan-based monomer-derived unit, and an aromatic vinyl-based monomer-derived unit, the graft copolymer is an acrylate-based polymer with a vinyl cyan-based monomer and An aromatic vinyl-based monomer may be graft-polymerized.
[36]
[37]
As the conjugated diene-based polymer, a conjugated diene-based monomer may be prepared and used by direct emulsion polymerization, or a commercially available conjugated diene-based polymer product may be purchased and used. form can be used. Specific types of the conjugated diene-based monomer include 1,3-butadiene, isoprene, chloroprene and piperylene, among which 1,3-butadiene is used with high frequency.
[38]
As the acrylate-based polymer, an acrylate-based monomer may be prepared and used by direct emulsion polymerization, or a commercially available acrylate-based polymer product may be purchased and used. form can be used. Specific types of the acrylate-based monomer include acrylate, methyl acrylate, ethyl acrylate and butyl acrylate, among which butyl acrylate is frequently used.
[39]
Specific types of the aromatic vinyl-based monomer include styrene, α-methyl styrene, α-ethyl styrene, and p-methyl styrene, among which styrene is frequently used.
[40]
Specific types of the vinyl cyan-based monomer include acrylonitrile, methacrylonitrile, ethacrylonitrile, phenylacrylonitrile and α-chloroacrylonitrile, among which acrylonitrile is used with high frequency. .
[41]
Meanwhile, "derived unit" in the present invention may mean a repeat unit derived from the compound included in the polymer or copolymer by participating in the polymerization reaction as a monomer in the polymer or copolymer. .
[42]
[43]
The whiteness (WI) of the graft copolymer according to the present invention may be 15 or more, preferably 20 or more. Through the method for preparing a graft copolymer of the present invention, which will be described later, when a graft copolymer is prepared, a graft copolymer having excellent whiteness can be prepared by being pelletized immediately in a reactant state. On the other hand, in order to improve the heat storage easiness of the existing dry powder, it may be considered to pelletize the dry powder again through an extruder, etc. Soot may be generated on the surface of the dry powder by the heat and pressure applied in the , and thus the whiteness of the final pellet may be lower than that of the graft copolymer of the present invention. When the graft copolymer exhibits high whiteness, it has the advantage that it can be easily applied to fields requiring various colors thereafter.
[44]
[45]
The present invention provides pellets formed from the graft copolymer as described above. The pellets of the present invention may have, for example, the shape of a sphere, a cylinder, or a polygonal column, and may have an irregular shape that is difficult to specify as a regular shape. A person skilled in the art can use it by appropriately adjusting the shape of the pellets as desired.
[46]
[47]
In the pellets of the present invention, the long diameter of the pellets may be 1mm to 5mm, preferably 2mm to 4mm, and the minor diameter may be 1mm to 5mm, preferably 2mm to 4mm. The major and minor diameters are defined as the length of the longest axis and the shortest axis among axes passing through the center of the pellet, respectively. When the long and short diameters of the pellets satisfy the above-mentioned ranges, the pellet size is appropriate, so that the problems that occur with the existing dry powder can be minimized, and manufacturing and storage are easy, and then it is used appropriately to meet the requirements of various industrial fields. can be
[48]
[49]
Method for preparing graft copolymer
[50]
The present invention provides the above-described method for preparing the graft copolymer together, and specifically, the method comprises graft polymerization of at least one of a vinyl cyanide monomer and an aromatic vinyl monomer to a conjugated diene-based polymer or an acrylate-based polymer. It may include a step (S1) of obtaining a reactant containing a graft copolymer and a step (S2) of molding the reactant into a pellet form through an extruder.
[51]
[52]
The step (S1) is a step for preparing a graft copolymer through emulsion polymerization as described above. The emulsion polymerization in this step may be carried out in the presence of an emulsifier, a polymerization initiator, an activator, or a molecular weight modifier, as known in the art.
[53]
For example, the emulsifier is sodium dicyclohexyl sulfosuccinate, sodium dihexyl sulfosuccinate, sodium di-2-ethylhexyl sulfosuccinate, potassium di-2-ethylhexyl sulfosuccinate, sodium dioctyl sulfosuccinate selected from the group consisting of phosuccinate, sodium dodecyl sulfate, sodium dodecyl benzene sulfate, sodium octadecyl sulfate, sodium oleic sulfate sodium salt, sodium dodecyl sulfate, potassium octadecyl sulfate, potassium rosinate and sodium rosinate. It may be one or more types, of which sodium dodecyl benzene sulfonate is preferable.
[54]
The emulsifier may be added in an amount of 0.1 to 2 parts by weight or 0.3 to 0.7 parts by weight based on 100 parts by weight of the monomer and polymer to be polymerized, of which 0.3 to 0.7 parts by weight is preferably added. Do. If the above-mentioned range is satisfied, the polymerization reaction may proceed stably and thus the formation of a coagulate may be suppressed.
[55]
[56]
The kind of polymerization initiator is sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, hydrogen peroxide, t-butyl peroxide, cumene hydroperoxide, p-mentane hydroperoxide, di-t-butyl peroxide, t- Butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanol peroxide, t-butyl peroxy isobutylate, azobis isobutyro It may be at least one selected from the group consisting of nitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and azobisisobutyric acid (butyl acid) methyl, of which t-butyl hydroperoxide is preferable The initiator may be added in an amount of 0.01 parts by weight to 1 part by weight or 0.05 parts by weight to 0.5 parts by weight based on 100 parts by weight of the monomer and polymer to be polymerized, of which 0.05 parts by weight to 0.5 parts by weight is preferably added. Do. When the above-described range is satisfied, the polymerization reaction may be uniformly performed, and thus the polymer produced may have more excellent impact resistance.
[57]
[58]
The activator may be at least one selected from the group consisting of sodium formaldehyde sulfoxylate, disodium ethylenediamine tetraacetate, ferrous sulfate, dextrose, sodium pyrophosphate, sodium pyrophosphate anhydiros and sodium sulfate, Among them, at least one selected from the group consisting of dextrose, ferrous sulfate and sodium pyrophosphate is preferable. The activator may be added in an amount of 0.01 parts by weight to 1 part by weight or 0.1 parts by weight to 0.5 parts by weight, of which 0.1 parts by weight to 0.5 parts by weight, based on 100 parts by weight of the monomer and polymer to be polymerized. desirable. When the above-mentioned range is satisfied, the flow index, impact resistance, and color characteristics of the prepared polymer may be excellent.
[59]
[60]
The molecular weight modifier is α-methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, carbon tetrachloride, methylene chloride, methylene bromide, tetraethyl thiuram disulfide, dipentamethylene thiuram It may be at least one selected from the group consisting of disulfide and diisopropylxanthogen disulfide, of which t-dodecyl mercaptan is preferable. The molecular weight regulator may be added in an amount of 0.01 parts by weight to 1.5 parts by weight or 0.1 parts by weight to 1 part by weight based on 100 parts by weight of the monomer and polymer to be polymerized, of which 0.1 part by weight to 1 part by weight is added desirable. If the above-mentioned range is satisfied, the balance between the flow index and the impact resistance in the polymer to be prepared may be excellent.
[61]
[62]
In addition, water may be used as the dispersion medium in this step.
[63]
[64]
The reactant including the graft copolymer prepared through the step (S1) described above has the form of an emulsion in which the graft copolymer is dispersed in water. Therefore, it is necessary to remove the dispersion medium of the reactant in order to selectively commercialize only the graft copolymer in the emulsion, and the reactant obtained through step (S1) of the present invention is then introduced into the extruder through step (S2) and reactant At the same time as the dispersion medium is removed, it is molded into pellets. The pellets may have a bulk density of 450 kg/m 3 to 700 kg/m 3 as described above .
[65]
Therefore, the extruder used in the present invention should be capable of suppressing the backflow of the dispersion medium removed during the extrusion process, while maximally removing the dispersion medium remaining in the reactant, for example, a sealing area that prevents the backflow of the dispersion medium inside the extruder. It should be something that can be formed. In the sealing region, the amount of reactant introduced into the sealing region and the amount of reactant exiting the sealing region are the same, so that the reactant does not substantially move in the region and fills the inside of the extruder to block gas or liquid movement back and forth in the region. means, and specifically, the sealing region may be formed through various internal configurations of the extruder, for example, may be formed by a ring structure inside the extruder or a combination of a reverse screw and a neutral screw. Due to such a sealing area, the backflow of the dispersion medium removed from the reactant during the extrusion process may be suppressed.
[66]
[67]
On the other hand, since the reactant prepared through step (S1) contains a large amount of dispersion medium, after removing some of the dispersion medium, when it is added to the extruder, subsequent pelletization may be more smooth. Therefore, the method for preparing the graft copolymer of the present invention further comprises the step (S1-1) of adjusting the moisture content of the reactant to less than 30% before the step (S2), wherein the extruder is provided with one or more vents It is characterized in that one, or the step (S1-2) of adjusting the moisture content of the reactant to 30% to 60% before the (S2) step (S1-2); further comprising, the extruder having two or more side slots It may be characterized by one thing.
[68]
In the case of including the step (S1-1) of adjusting the moisture content of the reactant to less than 30%, since the amount of the dispersion medium remaining in the reactant fed into the extruder is small, the dispersion medium is mostly vaporized due to the heat applied during the extrusion process, Accordingly, it is removed in a gaseous state. Accordingly, the extruder in this case is preferably provided with one or more vents in order to smoothly remove a large amount of gas. As the vent part, components used as a passage through which the evaporated material may pass in a conventional extruder such as a side vent stuffer, a side feeder, or an open barrel may be applied.
[69]
[70]
More specifically, the extruder having the vent unit may have the form of FIG. 1 . The extruder includes a barrel 10, a screw 30 mounted in the barrel 10, a vent unit 40 for discharging water vapor inside the barrel 10 to the outside, and a heater unit for heating the barrel 10 ( 60). In addition, a sealing region is formed in the barrel 10 by the molten raw material (reactant).
[71]
The barrel 10 has a hollow pipe shape along the longitudinal direction, a hopper 20 into which raw materials are fed is coupled to one side and dehydrated raw materials, that is, the graft copolymer of the present invention is discharged on the other side. A discharge port 11 is formed.
[72]
The barrel 10 is preferably made of a metal with excellent chemical resistance to prevent corrosion by volatile substances and water vapor discharged from the raw material, or the inner surface is coated with a protective material, etc. It is manufactured to have sufficient rigidity to withstand pressure.
[73]
The screw 20 has a rod shape, and has a structure in which a screw thread (M: 31) is formed on an outer circumferential surface. Then, the raw material input from the hopper 20 is transferred to the discharge port 11 while being mounted inside the barrel 10 and rotating in one direction.
[74]
At this time, the screw 30 is spirally formed along the longitudinal direction on the outer circumferential surface of the screw 30, and the portion where the screw M is formed in the direction of moving the raw material toward the inlet is the forward zone (F1, F2, F3 section) The part where the thread is formed so that the movement of the raw material is stopped and only rotation is made, or the part where the thread is formed so that the reverse movement of the raw material (i.e., moving from the outlet of the barrel to the hopper) is made is divided into a kneading zone (30A). .
[75]
Meanwhile, in the present invention, the screw 30 may have sections F1, F2, F3 in which a plurality of forward zones are formed and sections K1 and K2 in which a plurality of kneading zones are formed.
[76]
In the first forward zone, a forward screw thread 31 is formed so that the raw material input from the hopper 20 is transferred to the discharge port 11 when the shaft rotates, and the kneading zone 30A is the screw 30 when the shaft rotates. A neutral screw thread 32 or a reverse screw thread 33 is formed to compress the raw material transferred from the first forward zone. In addition, the sub-kneading zone 30B is also formed with a neutral thread 32 or a reverse thread 33 like the kneading zone 30A, and the second forward zone and the third forward zone have a forward thread like the first forward zone. is formed
[77]
In addition, after the raw material passes from the hopper 20 to the kneading zone 30A, the vent part 40 is mounted on the barrel 10 so that steam (and separated gas, etc.) is discharged. The vent unit 40 may be formed in the form of a simple tube opened to the upper side of the barrel 10, but an openable valve, an exhaust device for discharging water vapor by steel, and a safety vent that is opened only when the pressure is higher than a certain level are combined. may be provided.
[78]
In addition, a heater unit 60 for generating heat is coupled to the outer surface (or inside) of the barrel 10 . The heater unit 60 may be a device that converts electrical energy into thermal energy or a device that heats the barrel by receiving a heat source from the outside.
[79]
A plurality of the heater units 60 are mounted over the entire barrel, and each heater unit 60 is configured to be individually temperature controlled. Accordingly, the barrel 10 is configured to enable temperature control for each section (forwarding zone, kneading zone).
[80]
In the extrusion apparatus of the present invention having the configuration as described above, when the raw material stored in the hopper 20 is supplied into the barrel 10, the raw material is transferred inside the barrel 10 through the screw 30, and the heater Heating (and cooling) to the target temperature is achieved by the unit 60 .
[81]
At this time, when the raw material reaches the kneading zone 30A through the first forward zone, the raw material is pressed by the rotational force of the rear raw material and the screw 30 continuously supplied in a heated state.
[82]
Accordingly, the heated and pressurized raw material is melted in the kneading zone 30A (or before reaching the kneading zone), and at least a part or most of the raw material is phase-changed to a liquid state.
[83]
That is, the force is applied so that the raw material heated and pressurized in the kneading zone 30A is radially spread by the centrifugal force generated in the kneading zone 30A while the phase change is made from the solid state to the highly viscous liquid state.
[84]
Accordingly, in the front side (closer to the hopper) of the kneading zone 30A, the solid raw material and water vapor separated from the raw material spread to the space between the screw 30 and the barrel 10, and heat and pressure are continuously applied. As it acts, most of the solid fuel is melted in a liquid state in the rear side (closer to the discharge port) of the kneading zone 30A. At this time, the molten raw material forms a sealing region that shields the cross section of the barrel 10 by centrifugal force.
[85]
At this time, the thickness or formed position of the sealing area may vary depending on the rotation speed of the screw 30 , the heating temperature of the heater unit 60 , and the configuration of the threads formed in the kneading zone 30A, but the sealing area is the barrel. (10) It is formed in a fluid state rather than a fixed state inside.
[86]
That is, the sealing region is formed of a liquid film, and as the raw material is continuously supplied, the raw material that first formed the sealing region is discharged to the second forward zone through the kneading zone 30A, and the raw material supplied later becomes liquid and replenishes the previously discharged raw material and maintains the sealing area.
[87]
The heating temperature of the heater unit 60 and the shaft rotation speed of the screw are controlled according to the state and amount of the input material so that the sealing area can be continuously maintained.
[88]
The liquid raw material and gaseous water vapor that have passed through the kneading zone are transferred to the second forwarding zone area, where the liquid raw material is continuously transferred along the screw 30 while gaseous vapor (and phase gas generated during change) is discharged to the outside through the vent unit 40 . At this time, the reverse flow of the water vapor to the hopper 20 is blocked by the sealing area formed in the kneading zone 30A.
[89]
Then, the raw material that has reached the sub-kneading zone 30B forms a sealing area again in the sub-kneading zone 30B, and is discharged to the outlet 11 through the third forward zone. While being transported through the third forward zone, impurities (residual monomers, etc.) contained in the raw material, gas generated during phase change, and excess water vapor are discharged to the outside through the sub-vent unit 50 .
[90]
At this time, the raw material discharged to the discharge port 11 of the barrel 10 is discharged in the form of a solid mass after the separation of water vapor and gas and cooling.
[91]
The raw material discharged in the form of a solid mass is cut into pellets of a certain size by the crushing device 70 for pulverizing the dehydrated (dried) raw material.
[92]
On the other hand, in the extrusion apparatus of the present invention, it is preferable that the distance between each component is limited to increase drying and dehydration performance. Based on the diameter D of the barrel 10, the distance from the hopper 20 to the kneading zone 30A is preferably 5D to 10D, and between the kneading zone 30A and the vent part 40 It is preferable that the distance of is within 3D, the distance between the vent unit 40 and the sub-kneading zone 30B is 3D or more, and the distance between the sub-kneading zone 30B and the sub-vent unit 50 is set within 3D. However, these relative distances are not limited to the above range, and may vary depending on the length of the screw 30 , the shaft rotation speed, the state of the raw material, the output of the heater unit 60 , and the like.
[93]
In the extrusion apparatus of the present invention having the above configuration, a sealing area is formed in the kneading zone 30A while dehydration of the raw material is in progress in the barrel 10, thereby preventing or minimizing the reverse flow of water vapor toward the hopper 20. have a possible effect.
[94]
The kneading zone 30A may include one of a neutral zone or a reverse zone, or a combination of both, and thus may be selectively applied according to the state and properties of the raw material.
[95]
In addition, in the present invention, since the screw 30 may further include a sub-kneading zone 30B, it is possible to form an additional sealing area to more effectively block the reverse flow of water vapor, and to maximize water vapor from the vent unit 40 It may be possible to release
[96]
In addition, in the extrusion device of the present invention, since the moisture contained in the raw material is discharged to the vent unit 40 at the same time as the extrusion, it may be possible to discharge impurities (residual monomers, etc.) contained in the raw material in the sub vent unit 50 as much as possible. there is.
[97]
[98]
When including the step (S1-2) of adjusting the moisture content of the reactant to 30% to 60%, since the amount of the dispersion medium remaining in the reactant is relatively large, the dispersion medium is removed in a liquid state rather than a gaseous state during the extrusion process Accordingly, the extruder preferably has a side slot in order to smoothly remove the dispersion medium in the liquid state. In addition, when the moisture content is high, since the amount of the dispersion medium to be removed is large, the number of side slots is preferably two or more. On the other hand, the step (S1-2) of adjusting the moisture content of the reactant to 30% to 60% may specifically be a step of adjusting to 30 to 50%, more specifically 30 to 40%, and the number of the side slots may be 2 to 10, preferably 2 to 5.
[99]
On the other hand, a specific form of the extruder including the side slot may include slot parts 40A and 40B instead of the vent part in the configuration of the extruder including the vent part described above as shown in FIG. 2 .
[100]
The slot portions 40A and 40B are formed with a plurality of slots spaced apart from each other. The slot is formed in the shape of an elongated hole (hole), it is preferable to be arranged parallel to the longitudinal direction of the barrel (10).
[101]
In this case, the slots may be formed at regular intervals along the circumference of the barrel 10 . That is, in the case of the barrel 10 in the form of a cylindrical tube, the slot portion 40A may be formed so that the slots are arranged in a ring shape along the entire circumference of the barrel 10 . However, the slot may be configured to be formed only in a specific portion of the barrel 10 so as to control the discharge direction of water vapor inside the barrel 10 .
[102]
That is, when the slot is also formed in the lower part of the barrel 10 , moisture as well as a part of the raw material may be discharged by gravity, so that the slot may not be formed in the lower surface of the barrel 10 . In addition, for the above reasons, a slot of a specific portion may have a greater width or width than other slots. For example, the slot formed on the lower surface of the barrel 10 may be formed narrow and small to prevent the falling of the raw material, and the slot formed on the upper surface may be formed wider and larger to facilitate the discharge of water vapor.
[103]
In addition, the slot portions 40A and 40B may be provided in the form of simply perforated holes, but an openable and openable valve, an exhaust device for evacuating water vapor by steel, and a safety vent that is opened only when the pressure exceeds a certain level are additionally coupled can be
[104]
In addition, in the extruder including the slot part, based on the diameter (D) of the barrel 10, the distance from the hopper 20 to the kneading zone 30A is preferably set to 5D to 10D. And, the distance between the kneading zone 30A and the slot portion 40A is preferably determined to be 3D or less, and the distance between the slot portion 40A and the first sub-kneading zone 30B is preferably determined to be 3D or more. , the distance between the first sub-kneading zone 30B and the sub-slot part 40B and the distance between the sub-vent part 50 and the second sub-kneading zone 30C is preferably set within 3D.
[105]
However, these relative distances are not limited to the above range, and may vary depending on the length of the screw 30 , the shaft rotation speed, the state of the raw material, the output of the heater unit 60 , and the like.
[106]
In the extruder shown in FIG. 2, the configuration other than the slot part may be applied in the same manner as described in the extruder shown in FIG. 1 described above.
[107]
[108]
Control of the moisture content in the steps (S1-1) and (S1-2) may be performed through the same method as in the conventional dehydration and drying process, and a person skilled in the art can appropriately dehydrate and dry according to the desired moisture content range. It can be applied by selecting specific methods and devices of In addition, the "moisture content" in the present invention is not limited to the case where the dispersion medium is water, and even when a liquid other than water is used as the dispersion medium, the content of the dispersion medium remaining in the reactant can be referred to as "moisture content". .
[109]
[110]
Thermoplastic resin composition
[111]
The present invention provides a thermoplastic resin composition comprising the aforementioned graft copolymer and the thermoplastic resin.
[112]
[113]
The graft copolymer of the present invention may be mixed with various thermoplastic resins like the conventional dry powder of the graft copolymer to provide a thermoplastic resin composition.
[114]
Thermoplastic resins that can be mixed with the graft copolymer of the present invention include polystyrene-based resins including styrene-acrylonitrile (SAN) resins, poly(meth)acrylate-based resins, and polycarbonate resins.
[115]
The thermoplastic resin composition provided by the present invention can be widely applied to fields requiring various colors by exhibiting excellent whiteness while exhibiting satisfactory physical properties.
[116]
[117]
Hereinafter, preferred examples are presented to help the understanding of the present invention. However, the following examples are only illustrative of the present invention, and are not intended to limit the scope of the present invention.
[118]
[119]
Example 1
[120]
60 parts by weight of a polybutadiene polymer, 30 parts by weight of a styrene monomer, and 10 parts by weight of an acrylonitrile monomer were mixed in ion-exchanged water as a dispersion medium, and emulsified to prepare a reactant. After dehydrating the reactant to adjust the moisture content to 18%, it was immediately introduced into an extruder equipped with a vent in FIG. 1 to prepare pellets. The produced pellets had a major diameter of 3 mm and a minor diameter of 1.5 mm.
[121]
[122]
Example 2
[123]
The reactant prepared in Example 1 was subjected to dehydration treatment to adjust the moisture content to 33%, and then immediately put into an extruder having a slot portion of FIG. 2 to prepare pellets. The produced pellets had a major diameter of 3 mm and a minor diameter of 1.5 mm.
[124]
[125]
Comparative Example 1
[126]
The reactant prepared in Example 1 was prepared in the form of a dry powder through the processes of agglomeration, washing, dehydration and drying.
[127]
[128]
Comparative Example 2
[129]
50 parts by weight of a polybutyl acrylate polymer, 40 parts by weight of a styrene monomer, and 10 parts by weight of an acrylonitrile monomer were mixed in ion-exchanged water as a dispersion medium, followed by emulsification to prepare a reactant. The prepared reactant was prepared in the form of a dry powder through the processes of agglomeration, washing, dehydration and drying.
[130]
[131]
Experimental Example 1. Confirmation of the bulk density of the prepared copolymer
[132]
The bulk density of the copolymers prepared in Examples and Comparative Examples was measured. Specifically, after filling a container having a constant volume with the prepared copolymer, the weight was measured, and the bulk density was measured by dividing the measured weight by the container volume. The measurement results are shown in Table 1 below.
[133]
[134]
[Table 1]
Example 1 Example 2 Comparative Example 1 Comparative Example 2
Bulk density
(kg/m 3 ) 560 560 395 395
[135]
From the results of the above table, it was confirmed that the copolymer of the present invention had a higher bulk density than the copolymer in the dry powder form prepared by the conventional method because the graft copolymer particles were agglomerated with each other.
[136]
[137]
Experimental Example 2. Confirmation of occurrence of caking
[138]
It was confirmed whether a caking phenomenon occurred in the copolymers prepared in Example 2 and Comparative Example 1. Specifically, after filling a lubricated cylindrical mold (diameter 60Φ) with the manufactured copolymer, raising a load of a specific value, applying pressure to cause agglomeration of particles, and then removing the mold to check the shape By doing this, it was confirmed how much agglomeration of particles occurred and how much the aggregation was not resolved even after a certain period of time had elapsed. The results according to the applied load and the elapsed time are shown in FIG. 3 .
[139]
As shown in FIG. 3, in the case of the copolymer of Comparative Example 1 (DP) prepared in the form of dry powder, agglomeration occurred immediately after a load was applied, and a certain amount of aggregation was not resolved even after up to 15 days have elapsed. On the other hand, in the case of the copolymer of Example 2 (DPE) prepared in the form of pellets, when a low load is applied, agglomeration does not occur at all, and even when a relatively high load is applied, the agglomeration phenomenon is easily resolved compared to dry powder was confirmed.
[140]
[141]
Experimental Example 3. Yield strength measurement
[142]
Unconfined Yield Strength (Unconfined Yield Strength), which is the force when the formed cake shape is destroyed after the caking phenomenon was generated in the graft copolymers prepared in Example 2, Comparative Example 1 and Comparative Example 2 in the same manner as in Experimental Example 2 , UYS) were measured. The conditions for the occurrence of the caking phenomenon were 80° C., a pressure of 4.5 kg (15.7 kPa), and an elapsed time of 8 days, and the average value was taken after repeating 4 times to confirm reproducibility. Zwick was used as the measuring device of UYS. The measurement results are shown in Table 2 below.
[143]
[Table 2]
Example 2 Comparative Example 1 Comparative Example 2
UYS (kPa) Measurable 63.1 106.8
[144]
As can be seen from the above results, Comparative Examples 1 and 2 in the dry powder form required a certain amount of force until the cake form was destroyed, but in the case of Example 2 in the pellet form, the caking phenomenon itself did not occur well and yielded The intensity could not be measured. That is, in the graft copolymer of the present invention, the caking phenomenon hardly occurs, and even if it occurs, the cake can be easily destroyed to the extent that the yield strength cannot be measured, so that it is not strongly agglomerated during storage, whereas the existing dry powder is stored When the caking phenomenon occurred, it was confirmed that it was difficult to decompose them because they strongly aggregated with each other.
[145]
[146]
Experimental Example 4. Confirmation of whiteness and yellowness
[147]
The copolymer prepared in Comparative Example 1 was put back into the extruder to prepare pellets, and the whiteness (WI) and yellowness of the copolymer in the form of pellets prepared in Example 2 and the copolymer in the form of pellets prepared through Comparative Examples The degree (YI) was confirmed through a colorimeter. The results are shown in Table 3 below.
[148]
[Table 3]
L* a* b* WI YI
Example 2 83.02 -2.17 7.20 32.34 12.00
Comparative Example 1 69.32 -1.39 25.67 -29.71 43.67
[149]
In the index of Table 3, high whiteness means that the color of the prepared graft copolymer is close to white, and high yellowness means that the color of the prepared graft copolymer is close to yellow. As can be seen from the results of Table 3, the copolymer of Examples of the present invention prepared directly in the form of pellets shows high whiteness and low yellowness compared to the copolymer of Comparative Examples prepared in the form of pellets from dry powder, even when used with various pigments, etc. , it has been confirmed that the desired color can be accurately realized, so that it can be widely used in industrial fields requiring various colors.
[150]
[151]
Explanation of symbols
[152]
10 : Barrel
[153]
11: outlet
[154]
20 : Hopper
[155]
30: screw
[156]
30A to 30C: Kneading zone
[157]
31: thread
[158]
40: vent unit
[159]
40A: slot part
[160]
40B: sub slot part
[161]
50: sub vent unit
[162]
60: heater unit
[163]
70: crushing device
Claims
[Claim 1]
It contains at least one of a unit derived from a conjugated diene-based monomer and a unit derived from an acrylate-based monomer, and at least one of a unit derived from a vinyl cyanide-based monomer and a unit derived from an aromatic vinyl-based monomer, and has a bulk density of 450 kg/m 3 to 700 kg/m 3 phosphorus graft copolymer.
[Claim 2]
The graft copolymer according to claim 1, wherein the graft copolymer comprises a unit derived from a conjugated diene-based monomer, a unit derived from a vinyl cyanide-based monomer, and a unit derived from an aromatic vinyl-based monomer.
[Claim 3]
The graft copolymer according to claim 2, wherein the graft copolymer is a conjugated diene-based polymer by graft polymerization of a vinyl cyanide-based monomer and an aromatic vinyl-based monomer.
[Claim 4]
The graft copolymer according to claim 1, wherein the graft copolymer includes a unit derived from an acrylate-based monomer, a unit derived from a vinyl cyanide-based monomer, and a unit derived from an aromatic vinyl-based monomer.
[Claim 5]
The graft copolymer according to claim 4, wherein the graft copolymer is obtained by graft polymerization of a vinyl cyanide-based monomer and an aromatic vinyl-based monomer to an acrylate-based polymer.
[Claim 6]
The graft copolymer according to claim 1, wherein the graft copolymer has a whiteness (WI) of 15 or more.
[Claim 7]
A graft copolymer pellet formed from the graft copolymer of claim 1.
[Claim 8]
8. The graft copolymer pellets of claim 7, wherein the long diameter of the pellets is 1 mm to 5 mm.
[Claim 9]
The graft copolymer pellets according to claim 7, wherein the pellet has a minor diameter of 1 mm to 5 mm.
[Claim 10]
Graft polymerization of at least one of a vinyl cyan-based monomer and an aromatic vinyl-based monomer to a conjugated diene-based polymer or an acrylate-based polymer to obtain a reactant including a graft copolymer (S1); And molding the reactant in the form of pellets through an extruder (S2); Method for producing a graft copolymer comprising a.
[Claim 11]
The method of claim 10, wherein the pellets have a bulk density of 450 kg/m 3 to 700 kg/m 3 .
[Claim 12]
11. The method of claim 10, wherein, before the step (S2), adjusting the moisture content of the reactant to less than 30% (S1-1); including; the extruder having a side vent part. A method for preparing a copolymer.
[Claim 13]
11. The method of claim 10, Before the (S2) step, adjusting the moisture content of the reactant to 30% to 60% (S1-2); including; the extruder having two or more side slots Method for producing a graft copolymer, characterized in that.
[Claim 14]
The graft copolymer according to claim 1; and a thermoplastic resin; a thermoplastic resin composition comprising a.