KR101901877B1 - A method of preparing a functionalizable polyethylene wax - Google Patents

Abstract

An embodiment of the present invention provides a method for manufacturing polyethylene wax, comprising the steps of: (a) stirring and pyrolyzing polyethylene having a melting point of 110°C or less and a molecular weight distribution (Mw/Mn) of 10 to 15 at 445-455°C; and (b) cooling the product of the step (a) and injecting gas to induce a reaction, wherein the stirring is performed at 25-45 rpm.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a functionalized polyethylene wax,

The present invention relates to a process for producing a polyethylene wax, and more particularly to a process for producing a functionalized polyethylene wax by pyrolysis.

Wax refers to a material that is a solid such as a plastic at any temperature, but becomes a low viscous liquid when the temperature rises. Waxes can be broadly divided into plants and insects (beeswax), whales (wax), natural waxes extracted from minerals, and synthetic waxes produced from synthetic raw materials such as rubber trees, cotton and saturation. Representative synthetic waxes produced from synthetic raw materials include polyethylene (PE wax) and polypropylene (PP wax).

In particular, synthetic wax is an additive for improving the physical and chemical properties of plastics during plastic processing. As the chemical material technology to be applied is developed, various kinds of functional waxes required for such chemical materials are being developed. It is expanding.

Methods for producing the polyethylene wax include a polymerization method and a pyrolysis method. Polymerization is a process by which a chain transfer agent or hydrogen is added to produce an ethylene monomer by a high temperature polymerization or a low pressure under pressure using an appropriate catalyst. This enables operation in a continuous process, However, there is a problem that it is difficult to diversify the breed because the apparatus is enormous and the investment cost is large.

Pyrolysis of polyethylene is evident at the point of chain branching of the polymer. It is possible to obtain pyrolyzed polyethylene having a relatively narrow molecular weight as compared with a high molecular weight polyethylene which has not been improved upon pyrolysis.

However, since the pyrolysis reaction requires a high temperature of 400 ° C or higher and a long reaction time, energy efficiency is low. In addition, all processes in which low molecular weight polyethylene such as wax obtained by pyrolysis is produced are not completely pyrolyzed due to low thermal conductivity of polyethylene, and it is difficult to produce a product having a uniform molecular weight. In order to solve this problem, there has been proposed a thermal decomposition reaction in an appropriate heat resistant solvent. However, there is a problem that the subsequent step for removing the used solvent is further required, thereby increasing the cost.

On the other hand, since polyethylene is essentially non-polar, when it is mixed with other materials having a polarity, the physical properties are greatly deteriorated due to weak interaction at the interface, which may limit the application field.

The most common method for functionalizing nonpolar polyethylene wax is copolymerization of acrylic acid or the like during ethylene polymerization to introduce a polar group into the main chain of the polyethylene wax.

However, this is merely a method and a condition for imparting polarity to the polyethylene wax, and the physical properties of the polyethylene wax which is advantageous for functionalization and the method for producing the polyethylene wax for optimizing the polyethylene wax in the pre- to be.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method for producing a polyethylene wax which can find and optimize properties of a polyethylene wax favorable for functionalization or modification.

(A) stirring and pyrolyzing polyethylene having a melting point of 110 ° C or less and a molecular weight distribution (Mw / Mn) of 10 to 15 at 445 ° C to 455 ° C; And (b) cooling the product of step (a) and injecting gas into the reaction mixture, wherein the stirring is performed at 25 rpm to 45 rpm.

In one embodiment, the pyrolysis may be performed at 450 ° C to 455 ° C.

In one embodiment, the stirring may be performed at 30 rpm to 45 rpm.

In one embodiment, the polyethylene wax may have a molecular weight distribution (Mw / Mn) of from 6 to 8.

In one embodiment, the number average molecular weight (Mn) of the polyethylene wax may range from 2,500 to 3,600.

In one embodiment, the viscosity of the polyethylene wax may be 400 cps to 800 cps at 140 占 폚.

In one embodiment, the softening point of the polyethylene wax may be between 105 캜 and 110 캜.

In one embodiment, the degree of penetration of the polyethylene wax may be between 2 dmm and 2.5 dmm.

In one embodiment, the gas may be air.

In one embodiment, the gas may further comprise one or more inert gases.

In one embodiment, the cooling may be performed at 100 < 0 > C to 180 < 0 > C.

The method of producing polyethylene wax according to one aspect of the present invention is characterized in that the viscosity, softening point, and penetration degree of the polyethylene wax are controlled by adjusting the melting point and the molecular weight distribution of the raw material to a certain range and controlling the reaction temperature and stirring speed during the thermal decomposition to a certain range It is possible to adjust the range to the optimum range required.

It should be understood that the effects of the present invention are not limited to the effects described above, but include all effects that can be deduced from the description of the invention or the composition of the invention set forth in the claims.

Hereinafter, the present invention will be described. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

(A) stirring and pyrolyzing polyethylene having a melting point of 110 ° C or less and a molecular weight distribution (Mw / Mn) of 10 to 15 at 445 ° C to 455 ° C; And (b) cooling the product of step (a) and injecting gas into the reaction mixture, wherein the stirring is performed at 25 rpm to 45 rpm.

The polyethylene is a raw material of the polyethylene wax. When the polyethylene is pyrolyzed under a predetermined condition, the polyethylene wax having the required physical properties can be obtained.

The melting point of the polyethylene may be 110 ° C or less, preferably 100 ° C to 110 ° C, and the molecular weight distribution (Mw / Mn) may be 10-15. In addition, the decomposition temperature of the polyethylene may be 342 ° C to 350 ° C, the polyethylene purity may be 99% by weight or more, and the melt index may be 5.0 to 10.0.

In particular, when the melting point of the polyethylene exceeds 110 ° C, the softening point of the wax obtained after pyrolysis becomes excessively high, making it difficult to function. Further, even if the decomposition temperature of the polyethylene is less than 342 DEG C or the purity is less than 99 wt%, the softening point of the wax obtained after pyrolysis becomes excessively high, making it difficult to function.

The reaction temperature during the pyrolysis may be from 445 to 455 ° C, and preferably from 450 to 455 ° C. If the reaction temperature is lower than 445 ° C, the viscosity and softening point of the wax may excessively increase and the penetration may decrease. If the reaction temperature is higher than 455 ° C, the viscosity of the wax may excessively decrease and the penetration may increase. That is, if the reaction temperature is outside the range of 445 ° C to 455 ° C, the optimum viscosity, softening point, and penetration required for functionalization of the wax to be described later can not be satisfied.

The pyrolysis may be carried out under stirring conditions of a constant rate. At this time, the stirring speed may be 25 rpm to 45 rpm, preferably 30 rpm to 45 rpm. If the stirring speed is less than 25 rpm, the viscosity of the wax may excessively decrease and the penetration may excessively increase. If the stirring speed exceeds 45 rpm, the softening point of the wax may excessively increase. That is, if the stirring speed is out of the range of 25 rpm to 45 rpm, the optimum viscosity, softening point, and penetration required for functionalization of the wax to be described later can not be satisfied.

The cooling may be performed at 100 캜 to 180 캜, and preferably 140 캜 to 160 캜. If the cooling is less than 100 ° C, the temperature may be low and the gas may be difficult to activate. If it is more than 180 ° C, the temperature may be high, and side reactions may occur, thereby deteriorating the physical properties of the polyethylene wax.

The gas may be air. The air is composed of nitrogen and oxygen, so that oxygen having a non-covalent electron pair can be activated in the active oxygen and / or radical state to promote pyrolysis and oxidation of the polyethylene wax.

The gas may further comprise one or more inert gases, preferably one selected from helium, argon or a compound thereof. The inert gas may be further included to control the reaction activity depending on the gas injection.

The polyethylene having a molecular weight distribution (Mw / Mn) of 10 to 15 can be converted into a polyethylene wax having a molecular weight distribution (Mw / Mn) of 6 to 8 by the thermal decomposition. Specifically, the molecular weight distribution of the polyethylene may be reduced by the pyrolysis, and the number average molecular weight (Mn) of the polyethylene wax may be 2,500 to 3,600. If the number average molecular weight is out of the above range, the softening point of the wax obtained after pyrolysis becomes excessively high and is hardly functionalized.

On the other hand, by controlling the physical properties of the polyethylene wax, specifically, the viscosity, the softening point and the penetration into a certain range, a polyethylene wax having a form favorable for functionalization or modification can be obtained.

For example, the functionalization may be, but is not limited to, hydrophilic reforming of a wax that is essentially hydrogen.

The method of modifying the hydrophobic wax to be hydrophilic may be, for example, by grafting a reactive monomer such as acrylic acid or maleic anhydride to the polyethylene wax, but is not limited thereto.

The viscosity of the polyethylene wax may be 400 cps to 800 cps, preferably 450 cps to 750 cps, more preferably 500 cps to 700 cps at 140 캜.

The polyethylene wax may have a softening point of from 105 캜 to 110 캜, preferably from 107 캜 to 110 캜. As used herein, the term "softening point" means the temperature at which a material begins to soften by heating. Generally, the softening point is measured by various methods prescribed to measure a specific step of the softening process, and the resulting softening point shows different values depending on the measuring method. In the present invention, it means a value measured according to ASTM D 36.

The degree of penetration of the polyethylene wax may be from 2 dmm to 2.5 dmm. As used herein, the term "intrusion degree" is a measure of the degree of toughness or hardness of a material. A certain shape of needle, cone, or wedge is penetrated in a certain amount of time Depth. Means a value measured in accordance with ASTM D 1321 in the present invention.

If the viscosity, softening point and penetration of the polyethylene wax satisfy the above range, the polyethylene wax may have a form suitable for hydrophilization.

Hereinafter, embodiments of the present invention will be described in detail.

Examples and Comparative Examples

After 2 kg of the raw polyethylene resin having the physical properties shown in the following Table 1 was charged into the reactor, nitrogen was injected into and discharged from the reactor to remove oxygen present in the reactor. Thereafter, the polyethylene resin was pyrolyzed for 3 hours by adjusting the temperature and stirring speed of the reactor.

The pyrolyzed product was cooled to 155 DEG C and then further reacted while air was supplied for 60 minutes while the temperature of the reactor reached 5 kgf / cm < ² > to obtain an oxidized polyethylene wax. The pyrolysis conditions in the examples and comparative examples and the results of the physical properties of the obtained products are shown in Tables 2 to 5 below. The physical properties test method is as follows.

- Viscosity (cps, @ 140 ° C): measured according to ASTM D 1986-91

- Softening point (캜): Measured according to ASTM D 36

- Intrusion (dmm): Measured according to ASTM D 1321

- molecular weight, molecular weight distribution: measured by gas permeation chromatography (GPC)

division Melt Index
(g / 10 min) Decomposition temperature
(° C) Polyethylene purity
(%) Melting point
(° C) Raw material A 7.5 348.17 99.65 107.22 Raw material B 10 342.06 99.69 105.43 Raw material C 7.5 340.47 98.11 115.45

Raw material A rpm Pyrolysis temperature Cooling temperature Viscosity Softening point Intrusion Comparative Example 1-1 22 453 155 300 108.0 2.3 Example 1-1 27 453 155 410 108.5 2.4 Examples 1-2 32 453 155 490 108.7 2.4 Example 1-3 37 453 155 550 108.8 2 Examples 1-4 42 453 155 610 109.4 2 Comparative Example 1-2 42 443 155 1,175 111.1 1.8 Examples 1-5 42 448 155 750 110.2 2.1 Comparative Example 1-3 42 458 155 350 107.2 2.7 Comparative Example 1-4 42 463 155 230 106.6 3.4

Comparative Example 1-1, in which the stirring speed was less than 25 rpm, had a viscosity of less than 400 cps, a pyrolysis temperature of less than 445 ° C., and Comparative Example 1-2 in which the gas was not introduced, had viscosity, softening point and penetration Greater than 800 cps, greater than 110 < 0 > C, and less than 2.0 dmm. In Comparative Examples 1-3 and 1-4 in which the thermal decomposition temperature was higher than 455 ° C, the viscosity and the penetration were less than 400 cps and more than 2.5 dmm, respectively. In the other Examples 1-1 to 1-5, the viscosity, the softening point and the penetration degree were in the range of 400 to 800 cps, 105 to 110 ° C and 2.0 to 2.5 dmm, respectively.

Raw material B rpm Pyrolysis temperature Cooling temperature Viscosity Softening point Intrusion Comparative Example 2-1 22 453 155 340 105.8 3.3 Example 2-1 27 453 155 460 107.7 2.4 Example 2-2 32 453 155 610 106.8 2.4 Example 2-3 37 453 155 770 108.5 2 Examples 2-4 42 453 155 800 108.9 2 Comparative Example 2-2 32 443 155 1,475 111.1 1.8 Example 2-5 32 448 155 765 109.1 2.0 Comparative Example 2-3 32 458 155 410 107.2 2.7 Comparative Example 2-4 32 463 155 280 106.9 3.4

Comparative Example 2-1, in which the stirring speed was less than 25 rpm, had a viscosity and penetration of less than 400 cps, more than 2.5 dmm, a pyrolysis temperature of less than 445 캜, and Comparative Example 2-2 The viscosity, the softening point, and the penetration degree exceeded 800 cps, respectively, exceeding 110 ° C and less than 2.0 dmm. Comparative Examples 2-3 and 2-4 having a pyrolysis temperature higher than 455 ° C had an invasion degree exceeding 2.5 dmm and Comparative Example 2-4 had a viscosity lower than 400 cps. In the other Examples 2-1 to 2-5, the viscosity, the softening point and the penetration degree were in the range of 400 to 800 cps, 105 to 110 ° C and 2.0 to 2.5 dmm, respectively.

division Mn Mw PD (Mw / Mn) Raw material A 34,629 382,090 11.03 Examples 1-4 2,953 21,633 7.33 Raw material B 21,869 321,273 14.69 Example 2-2 3,565 21,879 6.14

Referring to Table 4, after the thermal decomposition reaction, the molecular weight distribution of the raw material A decreased from 11.03 to 7.33, and the molecular weight distribution of the raw material B decreased from 14.69 to 6.14. The polyethylene waxes of Examples 1-4 and 2-2 had a number average molecular weight (Mn) of 2,953 and 3,565, respectively, satisfying the range of 2,500 to 3,600.

Raw material C rpm Pyrolysis temperature Cooling temperature Viscosity Softening point Intrusion Comparative Example 3-1 22 453 155 305 111.4 3.3 Comparative Example 3-2 27 453 155 390 112.6 3 Comparative Example 3-3 32 453 155 495 113.3 3.1 Comparative Example 3-4 37 453 155 550 115 2.5 Comparative Example 3-5 42 453 155 610 115.4 2.6 Comparative Example 3-6 42 443 155 1,150 115.2 1.9 Comparative Example 3-7 42 448 155 730 114.4 2.2 Comparative Example 3-8 42 458 155 330 112.9 2.7 Comparative Example 3-9 42 463 155 240 112.9 3.3

Referring to Table 5, in Comparative Examples 3-1 to 3-9 in which raw material C having a melting point exceeding 110 ° C, a decomposition temperature lower than 342 ° C and a polyethylene purity lower than 99% by weight was pyrolyzed, viscosity, softening point and penetration Was out of the range according to the embodiment of the present invention. In particular, it was experimentally confirmed that the softening point was all above 110 DEG C, and thus it was inadequate for functionalization.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (11)

(a) stirring and pyrolyzing polyethylene having a melting point of 110 占 폚 or less and a molecular weight distribution (Mw / Mn) of 10 to 15 at 445 占 폚 to 455 占 폚; And
(b) cooling the product of step (a) and injecting gas to react,
Characterized in that the stirring is carried out at 25 rpm to 45 rpm. The method according to claim 1,
Characterized in that the pyrolysis is carried out at 450 ° C to 455 ° C. The method according to claim 1,
Characterized in that the stirring is carried out at 30 rpm to 45 rpm. The method according to claim 1,
Wherein the polyethylene wax has a molecular weight distribution (Mw / Mn) of 6 to 8. 5. The method of claim 4,
Wherein the polyethylene wax has a number average molecular weight (Mn) of 2,500 to 3,600. The method according to claim 1,
Wherein the polyethylene wax has a viscosity of 400 cps to 800 cps at 140 占 폚. The method according to claim 1,
Wherein the polyethylene wax has a softening point of 105 ° C to 110 ° C. The method according to claim 1,
Wherein the degree of penetration of the polyethylene wax is from 2 dmm to 2.5 dmm. The method according to claim 1,
Wherein the gas is air. 10. The method of claim 9,
Wherein the gas further comprises at least one inert gas. The method according to claim 1,
Characterized in that the cooling is carried out at from 100 캜 to 180 캜.