阅读说明：本技术 氯乙烯类聚合物及其制备方法 (Vinyl chloride polymer and process for producing the same ) 是由 李世雄 安晟镕 金健地 于 2019-08-07 设计创作，主要内容包括：本发明涉及一种具有优异的混合性能,从而具有改善的加工性能的氯乙烯类聚合物的制备方法,以及由此制备的氯乙烯类聚合物,所述氯乙烯类聚合物的由等式1定义的粒子非均匀度为10以上。(The present invention relates to a method for preparing a vinyl chloride-based polymer having excellent mixing properties and thus improved processability, the vinyl chloride-based polymer having a particle non-uniformity defined by equation 1 of 10 or more, and a vinyl chloride-based polymer prepared thereby.)

1. A vinyl chloride-based polymer having a particle non-uniformity of 10 or more as defined by the following equation 1:

[ equation 1]

Non-uniformity of particles

In the above equation 1, X_iIs a standard deviation of the ith particle, and is a value defined by the following equation 2,

[ equation 2]

In equation 2 above, A_nIs a correction value of the nth measured diameter of the ith particle, and the correction value is a value defined by the following equation 3,

[ equation 3]

In the above equation 3, D_nIs the nth measured diameter, D, of the ith particle₀Is the longest diameter of the ith particle, and n is an integer of 1 to 50.

2. The vinyl chloride-based polymer according to claim 1, wherein the particle non-uniformity of the vinyl chloride-based polymer is 11 to 16.

3. The vinyl chloride-based polymer according to claim 1, wherein the vinyl chloride-based polymer is a bulk polymer.

4. The vinyl chloride-based polymer according to claim 1, wherein the vinyl chloride-based polymer has a porosity of 59% or more.

5. A process for producing the vinyl chloride-based polymer according to claim 1, which comprises:

adding a prepolymerization initiator to the first vinyl chloride-based monomer and conducting prepolymerization at a pressure of 8.0K/G to 8.7K/G to form a particle core; and

post-polymerizing a second vinyl chloride monomer and a post-polymerization initiator in the presence of the particle core, wherein,

the prepolymerization initiator is added at a low pressure of 1.3K/G to 3.5K/G, compared to the pressure during prepolymerization, and,

the vinyl chloride-based polymer has a particle non-uniformity defined by the following equation 1 of 10 or more:

[ equation 1]

Non-uniformity of particles

In the above equation 1, X_iIs a standard deviation of the ith particle, and is a value defined by the following equation 2,

[ equation 2]

In equation 2 above, A_nIs a correction value of the nth measured diameter of the ith particle, and the correction value is a value defined by the following equation 3,

[ equation 3]

In the above equation 3, D_nIs the nth measured diameter, D, of the ith particle₀Is the longest diameter of the ith particle, and n is an integer of 1 to 50.

6. The production method according to claim 5, wherein the prepolymerization initiator is added at a low pressure of 1.5K/G to 3.0K/G as compared with the pressure during the prepolymerization.

7. The production method according to claim 5, wherein the preliminary polymerization initiator is added in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the first vinyl chloride-based monomer.

8. The production method according to claim 5, wherein the prepolymerization is carried out to a polymerization conversion rate of 10 to 15%.

9. The production method according to claim 5, wherein the post-polymerization is carried out at a pressure of 6K/G to 13K/G.

10. The production method according to claim 5, wherein the post-polymerization initiator is used in an amount of 0.05 to 2 parts by weight, based on 100 parts by weight of the second vinyl chloride-based monomer.

11. The production method according to claim 5, wherein the pre-polymerization initiator and the post-polymerization initiator are each one or more selected from the group consisting of di-2-ethylhexyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxide, isopropyl phenyl peroxyneodecanoate, 1,3, 3-tetramethylbutyl peroxyneodecanoate, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, di-sec-butyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, isobutyryl peroxide, 3,5, 5-trimethylhexanoyl peroxide, lauryl peroxide, and octyl peroxydicarbonate.

Technical Field

Cross Reference to Related Applications

This application claims the rights of korean patent application No.10-2018-0113823 filed at the korean intellectual property office at 21.9.2018 and korean patent application No.10-2019-0094160 filed at 8.2.2019 at the korean intellectual property office, the disclosures of both of which are incorporated herein by reference in their entirety.

Background

The vinyl chloride-based polymer is a polymer containing vinyl chloride of more than 50%, is inexpensive, and has hardness easily controlled. Therefore, since vinyl chloride polymers can be applied to most processing apparatuses, the fields of application thereof are various. In addition, the vinyl chloride-based polymer can provide molded articles excellent in physical and chemical properties, for example, mechanical strength, weather resistance, chemical resistance, etc., and thus, is widely used in various fields.

Meanwhile, a vinyl chloride-based polymer is mixed with an auxiliary raw material to be applied to various fields. In this case, when the surface of the vinyl chloride-based polymer particles is smooth, the bonding force with the auxiliary raw material may be poor, resulting in deterioration of mixing properties and poor processability.

Such a vinyl chloride-based polymer is prepared by bulk polymerization, suspension polymerization or emulsion polymerization according to its purpose, for use. Among them, unlike suspension polymerization or emulsion polymerization, preparation by bulk polymerization is performed using a vinyl chloride-based monomer, an initiator, and other reaction additives without using a medium such as water, and thus a drying process is not required. Therefore, the preparation by bulk polymerization has a relatively low production cost, and thus, is widely used in industry.

However, most of the vinyl chloride-based polymer particles produced by bulk polymerization have smooth and angular surfaces (see fig. 1), and therefore, the bonding force with the auxiliary raw material during mixing is low when compared with a vinyl chloride-based polymer produced by suspension polymerization and thus having a non-uniform surface (see fig. 2). As a result, the mixed materials aggregate, resulting in poor processability.

Therefore, in order to further improve the industrial applicability of the vinyl chloride-based polymer produced by bulk polymerization, which is advantageous in terms of production cost, a method of roughening the surface of particles of the vinyl chloride-based polymer produced by bulk polymerization is required.

Disclosure of Invention

Technical problem

An aspect of the present invention provides a vinyl chloride-based polymer having excellent processability and having controlled unevenness of particle surface.

Another aspect of the present invention provides a method for producing a vinyl chloride-based polymer.

Technical scheme

According to an aspect of the present invention, there is provided a vinyl chloride-based polymer having a particle non-uniformity of 10 or more as defined by the following equation 1:

[ equation 1]

Non-uniformity of particles

In the above equation 1, X_iIs a standard deviation of the ith particle, and is a value defined by the following equation 2,

[ equation 2]

In equation 2 above, A_nIs a correction value of the nth measured diameter of the ith particle, and the correction value is determined by the following equation 3The value of the sense is such that,

[ equation 3]

In the above equation 3, D_nIs the nth measured diameter, D, of the ith particle₀Is the longest diameter of the ith particle, and n is an integer of 1 to 50.

According to another aspect of the present invention, there is provided a method for producing a vinyl chloride-based polymer having a particle non-uniformity of 10 or more as defined by the following equation 1, the method comprising: adding a pre-polymerization initiator to the first vinyl chloride-based monomer and performing pre-polymerization at a pressure of 8.0K/G to 8.7K/G to form a particle core (step 1); and performing a post-polymerization on the second vinyl chloride-based monomer and the post-polymerization initiator in the presence of the particle core (step 2), wherein the pre-polymerization initiator is added at a low pressure of 1.3K/G to 3.5K/G as compared with the pressure during the pre-polymerization.

Advantageous effects

The vinyl chloride-based polymer according to the present invention is produced by the above production method in which the pressure conditions and the time point of addition of the preliminary polymerization initiator are controlled during preliminary polymerization, whereby the particle non-uniformity can be controlled and high porosity can be obtained. As a result, the mixing property is improved, so that the processability can be excellent.

In addition, the production method of a vinyl chloride-based polymer according to the present invention can control the surface of the particle core at the start of the reaction by controlling the pressure during the prepolymerization in the prepolymerization step for forming the particle core, and by adding the prepolymerization initiator at a low pressure of 1.3K/G to 3.5K/G as compared with the pressure during the prepolymerization to allow the prepolymerization initiator to participate in the prepolymerization, and therefore, a vinyl chloride-based polymer having controlled particle non-uniformity and porosity can be produced.

Therefore, the method for producing a vinyl chloride-based polymer according to the present invention and the vinyl chloride-based polymer produced thereby can be easily applied to industries requiring it, for example, industries relating to vinyl chloride-based resins and molded articles.

Drawings

The following drawings attached to the present specification illustrate specific embodiments of the present invention by way of example and together with the detailed description of the invention given below serve to enable the technical idea of the invention to be further understood, and the invention should not be construed as having only the contents of these drawings.

Fig. 1 is a Scanning Electron Microscope (SEM) image showing particles of vinyl chloride polymer prepared by a conventional bulk polymerization method; and

fig. 2 is a Scanning Electron Microscope (SEM) image showing particles of vinyl chloride polymer prepared by a conventional suspension polymerization method.

Detailed Description

Hereinafter, the present invention will be described in more detail to help understanding of the present invention.

It should be understood that the words or terms used in the specification and claims of this invention should not be construed as limited to having the meanings defined in commonly used dictionaries. It should be further understood that the words or terms should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the technical idea of the present invention, based on the principle that the inventor can appropriately define the meaning of the words or terms to best explain the present invention.

The terms "first vinyl chloride-based monomer" and "second vinyl chloride-based monomer" used in the present invention are used to distinguish the order of participation in the reaction, and the substances themselves may represent the same vinyl chloride-based monomer.

The term "particle non-uniformity" used in the present invention means surface non-uniformity of particles or surface roughness of particles. The standard deviation between the diameters of 50 particles in the polymer in a plurality of directions was obtained, and the average value of the standard deviation between the diameters of the respective particles was defined as the particle non-uniformity. The smaller the value, the smaller the standard deviation between the diameters of the respective particles. That is, the diameters of the particles in a plurality of directions having similar values means that the particles are close to spherical, and thus, may mean that the surface roughness of the particles is low, or smooth.

The unit "K/G (kgf/cm) used in the present invention²) "is a unit representing pressure, and 1K/G may be equal to 0.968 atm.

The present invention provides a vinyl chloride-based polymer having excellent processability by controlling the degree of non-uniformity of particles to improve mixing properties.

The vinyl chloride-based polymer according to an embodiment of the present invention can be prepared by a preparation method in which polymer-forming particles have a controlled surface roughness and, therefore, can have improved mixing properties to have excellent processability.

Specifically, the vinyl chloride-based polymer is characterized in that the particle non-uniformity defined by the following equation 1 is 10 or more. More specifically, the particle heterogeneity of the vinyl chloride-based polymer may be 11 to 16.

[ equation 1]

Non-uniformity of particles

In the above equation 1, X_iIs a standard deviation of the ith particle, and is a value defined by the following equation 2,

[ equation 2]

In equation 2 above, A_nIs a correction value of the nth measured diameter of the ith particle, and the correction value is a value defined by the following equation 3,

[ equation 3]

In the above equation 3, D_nIs the nth measured diameter, D, of the ith particle₀Is the longest diameter of the ith particle, and n is an integer of 1 to 50.

In addition, the gel rate of the vinyl chloride-based polymer according to an embodiment of the present invention may be 50 seconds or more and 80 seconds or less. The vinyl chloride-based polymer according to the present invention has the above-mentioned unevenness of the particle surface, and therefore, can exhibit a gelation rate within the above-mentioned range, thereby having excellent processability.

In this case, the gelation rate is obtained by: 50g of a dry mixture prepared by mixing 2 parts by weight of a heat stabilizer and 2 parts by weight of epoxidized soybean oil to 100 parts by weight of a vinyl chloride-based polymer was added to a Brabender Torque Rhomixer and the mechanical load occurring when the dry mixture was melted at 30rpm at 165 ℃ was recorded and measured.

In addition, the vinyl chloride-based polymer according to an embodiment of the present invention may have a porosity of 59% or more, specifically 59% to 65% or 60% to 63%, and may be excellent in processability since the plasticizer absorption rate is increased in this range without deterioration of mechanical properties.

Here, the porosity was calculated from the amount of mercury permeated into each vinyl chloride polymer particle using a mercury porosimeter (AutoPore IV 9520, Micromeritics Co, Ltd.).

Meanwhile, the vinyl chloride-based polymer according to an embodiment of the present invention may be a bulk polymer.

In addition, the present invention provides a method for producing a vinyl chloride-based polymer having controlled unevenness of particle surface.

Generally, the vinyl chloride-based polymer is produced by bulk polymerization, suspension polymerization or emulsion polymerization. Among them, unlike suspension polymerization or emulsion polymerization, bulk polymerization can be performed without using a medium by adding only monomers, a polymerization initiator, and desired additives, and thus, a post-polymerization process such as a drying process is not required. Therefore, bulk polymerization has a low production cost and is easily applied to mass production, and thus, is widely used. However, in the case of a polymer prepared by bulk polymerization, the surface of polymer particles has a smooth and angular shape, and thus, the binding force with the auxiliary raw material during mixing is low as compared to a polymer prepared by suspension polymerization or emulsion polymerization, in which the surface of particles is rough. As a result, there is a problem of poor processability.

Accordingly, the present invention provides a method for producing a vinyl chloride-based polymer, wherein the vinyl chloride-based polymer is produced by bulk polymerization, and the shape of the particle surface is controlled by controlling the point of time at which a polymerization initiator is added at the start of polymerization.

The method for producing a vinyl chloride-based polymer according to one embodiment of the present invention is characterized in that a prepolymerization initiator is added to a first vinyl chloride-based monomer and prepolymerization is carried out at a pressure of 8.0K/G to 8.7K/G to form a particle core (step 1), and postpolymerization is carried out on a second vinyl chloride-based monomer and a postpolymerization initiator in the presence of the particle core (step 2), wherein the prepolymerization initiator is added at a low pressure of 1.3K/G to 3.5K/G as compared with the pressure during the prepolymerization.

Step 1 is a prepolymerization step for forming a particle core, and may be carried out by adding a prepolymerization initiator to a first vinyl chloride-based monomer, followed by prepolymerization. At this time, the prepolymerization can be carried out at a pressure of 8.0K/G to 8.7K/G, and the prepolymerization initiator can be added at a low pressure of 1.3K/G to 3.5K/G when compared with the pressure during the prepolymerization. Specifically, the prepolymerization initiator can be added at a low pressure of 1.5K/G to 3.0K/G when compared with the pressure during prepolymerization.

In the case of bulk polymerization, the polymerization is carried out in such a manner that the outer wall of the polymer particle is generated at the start of the reaction and fills the inside thereof. Therefore, in order to control the surface shape of the finally prepared polymer particles, the reaction rate must be controlled at the start of the reaction. The present invention can control the surface unevenness and porosity of the polymer particles to appropriate levels as described above by carrying out the prepolymerization under a pressure controlled to the above-specified range and adding the prepolymerization initiator to the first vinyl chloride-based monomer when the pressure reaches a low pressure of 1.3K/G to 3.5K/G when compared with the pressure during the prepolymerization.

Specifically, in step 1 according to the present invention, a first vinyl chloride-based monomer is introduced into a reactor, and then the pressure inside the reactor is raised to a predetermined pressure between 8.0K/G and 8.7K/G to perform prepolymerization. In the course of the pressure increase, when the pressure reaches a low pressure of 1.3K/G to 3.5K/G, specifically 1.5K/G to 3.0K/G, when compared with the pressure in the course of carrying out the prepolymerization, a prepolymerization initiator may be added.

In addition, the prepolymerization initiator may be added in an amount of 0.01 to 1 part by weight, and specifically, may be added in an amount of 0.03 to 0.1 part by weight, based on 100 parts by weight of the first vinyl chloride-based monomer. When the prepolymerization initiator is added within the above range, the reaction time can be properly controlled while the polymerization reaction can be smoothly initiated. In addition, since the heat amount of the reactant can be maintained at an appropriate level, a decrease in stability due to the reaction heat can be prevented, and problems such as a decrease in thermal stability due to the residual initiator can be minimized.

In addition, the prepolymerization initiator is not particularly limited. For example, a peroxyester or peroxydicarbonate compound may be used. Specifically, the prepolymerization initiator may be one or more selected from the group consisting of di-2-ethylhexyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxide, isopropyl phenyl peroxyneodecanoate, 1,3, 3-tetramethyl butyl peroxyneodecanoate, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, di-sec-butyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, isobutyryl peroxide, 3,5, 5-trimethylhexanoyl peroxide, lauryl peroxide and octyl peroxydicarbonate.

The first vinyl chloride-based monomer may be a vinyl chloride-based monomer or a mixture of a vinyl chloride-based monomer and a vinyl-based monomer copolymerizable with the vinyl chloride-based monomer. When the first vinyl chloride monomer is a mixture of a vinyl chloride monomer and a vinyl-based monomer, the mixture may be used in an appropriate amount such that 50% or more of vinyl chloride is contained in the vinyl chloride-based polymer thus prepared.

The vinyl-based monomer is not particularly limited. For example, olefinic compounds such as ethylene, propylene and butylene; vinyl esters such as vinyl acetate, vinyl propionate, and vinyl stearate; unsaturated nitriles such as acrylonitrile; vinyl alkyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl octyl ether and vinyl lauryl ether; vinylidene halides, such as vinylidene chloride; unsaturated fatty acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, and itaconic anhydride and anhydrides of the fatty acids; unsaturated fatty acid esters such as methyl acrylate, ethyl acrylate, monomethyl maleate, dimethyl maleate and butyl benzyl maleate; crosslinkable monomers, for example diallyl phthalate. Any one of them or a mixture of two or more of them may be used as the vinyl-based monomer.

Meanwhile, the prepolymerization of step 1 may be carried out until the polymerization conversion rate is 10 to 15%. There is no particular limitation in the polymerization conversion rate of the prepolymerization in step 1. However, prepolymerization is a step for producing a particle core, and when prepolymerization is excessively performed to excessively form a particle core, physical properties of a finally produced polymer may be changed to be different from an intended purpose. Therefore, it is necessary to control the degree of polymerization of the prepolymerization. If the preliminary polymerization is carried out up to the above polymerization conversion, a vinyl chloride-based polymer having a desired degree of non-uniformity can be produced without excessively forming particle cores, while not affecting the degree of polymerization and other physical properties.

At this time, the polymerization conversion rate represents a conversion rate of the first vinyl chloride monomer into a polymer, and can be measured using a butane tracer equipped with a gas chromatograph. Specifically, the polymerization conversion rate may be a value obtained by: under predetermined polymerization conditions satisfying the respective polymerization conditions, a polymerization conversion curve according to a ratio of vinyl chloride monomer to butane over time was plotted, and the polymerization conversion according to the polymerization conditions was measured based thereon. In addition, the polymerization conversion may even include a margin of error from the measurement.

In addition, the prepolymerization can be carried out at a temperature ranging from 30 ℃ to 70 ℃.

Step 2 is a step of producing a vinyl chloride-based polymer by growing the inside of the particle core produced in the preliminary polymerization, and may be carried out by performing a post-polymerization on the second vinyl chloride-based monomer and a post-polymerization initiator in the presence of the particle core produced in the preliminary polymerization step.

In this case, the postpolymerization may be carried out at a pressure of from 6K/G to 13K/G.

The second vinyl chloride-based monomer may be the same as the first vinyl chloride-based monomer.

The post-polymerization initiator may be added in an amount of 0.05 to 2 parts by weight, and specifically, may be added in an amount of 0.1 to 0.5 parts by weight, based on 100 parts by weight of the second vinyl chloride-based monomer.

Also, the post-polymerization initiator is not particularly limited. For example, the post-polymerization initiator may be one or more selected from the group consisting of di-2-ethylhexyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxyester, isopropyl phenyl peroxyneodecanoate, 1,3, 3-tetramethyl butyl peroxyneodecanoate, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, di-sec-butyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, isobutyryl peroxide, 3,5, 5-trimethylhexanoyl peroxide, lauryl peroxide, and octyl peroxydicarbonate. Also, the post-polymerization initiator may be the same as or different from the pre-polymerization initiator.

In addition, the post-polymerization may be performed under the temperature range condition of 30 ℃ to 70 ℃.

Meanwhile, the preparation method according to an embodiment of the present invention may remove the reactivity of the remaining post-polymerization initiator by adding a polymerization inhibitor at the end of post-polymerization. At this time, the polymerization inhibitor is not particularly limited, but for example, hydroquinone, butylated hydroxytoluene, monomethyl ether hydroquinone, quaternary butyl catechol, diphenylamine, triisopropanolamine, triethanolamine and the like can be used. In addition, the polymerization inhibitor may be used in an appropriate amount depending on the amount of the remaining post-polymerization initiator. In general, the polymerization inhibitor may be used in an amount of 0.001 to 0.1 parts by weight based on 100 parts by weight of the total of the vinyl chloride-based monomers used in the preliminary polymerization and the post polymerization.

In addition, the preparation method may use a reaction medium, and may also use additives such as a molecular weight regulator, as necessary.

The reaction medium is not particularly limited, and a conventional organic solvent may be used. For example, aromatic compounds such as benzene, toluene and xylene, methyl ethyl ketone, acetone, n-hexane, chloroform, cyclohexane, and the like can be used.

The molecular weight modifier is not particularly limited, and for example, n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, etc. can be used.

Hereinafter, the present invention will be described in more detail with reference to examples and experimental examples. However, the following examples and experimental examples merely illustrate the present invention and are not intended to limit the scope of the present invention.