JP2007084787A - Method for producing polyethylene wax - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems in which it is required to use separately prepared reactive material and other process for acid modification in addition to production of a non-oxidative type is required and polyethylene wax cannot be produced inexpensively and simply, because oxidative type polyethylene wax is produced by adding an organic peroxide compound (reaction initiator) such as DCP and a carboxylic acid compound such as phthalic anhydride to the melt of non-oxidative type polyethylene wax to carry out chemical reaction, substituting or grafting a hydrogen group of a part of polyethylene structure with an oxidation compound and introducing a carboxyl group into the structure to carry out acid modification. <P>SOLUTION: A method for producing polyethylene wax comprises passing through a process for previously carrying out heat-oxidative degradation of crosslinked polyethylene and burning and pyrolyzing the treated crosslinked polyethylene. As a result, oxidation type polyethylene wax can readily be produced without requiring to use separately prepared reactive material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a polyethylene wax, characterized by producing an oxidized type polyethylene wax in which a part of hydrogen groups in a polyethylene composition is substituted with a carbonyl group.

This type of polyethylene wax is used in various fields.
For example, 1. As a resin coloring aid that increases the wettability and dispersibility of the pigment by mixing in the resin containing the pigment and increases the pigment content. 2. In PVC (vinyl chloride resin) extrusion injection molding calendering As a lubricant, 3. As a release agent to be added to dry blending or kneading when molding thermoplastic resins such as styrene and PVC, thermosetting resins such as phenol polyurethane, 4. Wear resistance by mixing in printing ink It is used in various fields as an agent for improving properties and a sharpness-increasing agent.

  This oxidation type polyethylene wax has been conventionally manufactured by producing a non-oxidation type polyethylene wax and then melting the polyethylene wax by heating and melting or dissolving it in an organic solvent to obtain a DCP (dicumyl peroxide) or the like. An organic peroxide compound (reaction initiator) and a carboxylic acid compound such as phthalic anhydride are added and chemically reacted under the prescribed reaction conditions (simple radical reaction due to dissociation (radical generation) of peroxide such as DCP). Thus, some hydrogen groups in the polyethylene structure were substituted or grafted with an oxidized compound, and carboxyl groups were introduced into the structure (acid modification). (For example, Non-Patent Document 1)

Macromolecules 2003, 36 (13), P.4709-4718 `` Microstructure of Maleic Anhydride Grafted Polyethylene by High-Resolution Solution-State NMR and FTIR Spectroscopy '' LQ Yang, FR Zhang, t. Endo, T. Hirotsu

  However, in this way, the conventional manufacturing process needs to use a separately prepared reaction material separately from the process of manufacturing the non-oxidizing type polyethylene wax, and requires a separate process for acid modification. It was cheap and could not be easily manufactured.

  The present invention has been made in view of the above point, and has an acid value of 1 mg · KOH / g or more by previously thermally oxidizing and degrading crosslinked polyethylene, and then thermally decomposing the crosslinked polyethylene that has undergone thermal oxidation. It produces low molecular weight polyethylene.

  As described above, the present invention is manufactured by thermally oxidizing a cross-linked polyethylene prepared in advance with waste material or the like, and then subjecting it to combustion pyrolysis. It has the effect of producing wax.

The thermal oxidative degradation is performed in a heated air atmosphere using a heating device such as an oven.
The heating temperature is about 130 to 200 ° C, more preferably 150 to 180 ° C. If the temperature is lower than this, the progress of the oxidation reaction of the cross-linked polyethylene, which is the raw material, is slow, and if it is higher than this, the oxidative degradation (decomposition / deterioration) of the cross-linked polyethylene proceeds, and the wire waste material does not contain carbon as a compounding agent This is because, when the raw material is used as a raw material, significant discoloration is caused, and furthermore, carbonization proceeds to cause a decrease in yield during combustion pyrolysis.
Also, the heating time is about 24 to 1000 hours, according to the difference in the target value of the waste material thermal oxidation deterioration level at the stage of becoming the heating temperature of the oven and the raw material of thermal decomposition, and the acid value of the oxidized polyethylene wax to be produced. It can be changed as appropriate.

The combustion pyrolysis is disclosed in JP-A-60-190494, JP-A-10-128747, JP-A-2003-206373, etc., which are already known as methods for producing resin-based modifiers from electric wire waste. The method disclosed in is used.
That is, as shown in FIG. 1, in this resin-based modifier manufacturing apparatus, a bottomed cylindrical receiving tank T for storing a wax-like substance melt has a tank upper end opening 1b, and And supported by the support leg 1a.

  A cylindrical combustion basket 2 for heating and melting the raw material A such as synthetic resin waste material is integrally mounted and fixed in the tank upper end opening 1b of the reservoir tank T. A large number of air introduction holes 2 b are formed in the side wall of the combustion basket 2 in the thickness direction of the side wall so as to communicate the inside and the outside of the combustion basket 2.

  A closed box-shaped catalyst tank (deplasticization promoting basket) 4 is attached to the lower end opening 2a of the combustion basket 2 so as to close the lower end opening 2a from below. The catalyst tank 4 has a net-like part 4a whose entire wall is porous, and a metal catalyst for promoting deplasticization of the melt B, for example, a linear shape made of platinum or copper, in the catalyst tank 4. The catalyst 4b is filled so that the melt B can pass through.

  A cylindrical air balancer 5 for adjusting the amount of air supplied to the combustion basket 2 is installed at a predetermined interval with respect to the outer periphery of the combustion basket 2 so as to cover the outer periphery of the combustion basket 2. An air introduction opening 5 a is provided in the lower part of the air balancer 5.

  In order to efficiently send the flammable hot gas G generated in the reservoir tank T into the combustion basket 2 between the reservoir tank T and the combustion basket 2, a communication pipe 9. Are installed along the vertical direction with respect to the outer wall of the reservoir tank T. Each communication pipe 9 is provided with a pump 10 for sending the gas from the reservoir tank T to the combustion basket 2 in order to promote the delivery of the hot gas G.

  A pipe-like heater 6 is installed at the inner bottom of the reservoir tank T as a heating means for raising the melting temperature of the wax-like substance C by electric heating. In addition, a temperature sensor 7 such as a bimetal or a thermocouple for detecting the melting temperature of the wax-like substance C is installed inside the reservoir tank T as temperature detection means.

  The heater 6 is provided with control means 8 such as a microcomputer for controlling on / off or proportional control of the heater 6 so as to keep the melt of the wax-like substance C at a predetermined temperature.

  In the lower part of the combustion basket 2, the rooster 3, which is a raw material tray for placing the raw material A and melting and pyrolyzing it, closes the lower end opening 2 a of the combustion basket 2 from above. These are attached to the peripheral wall in the combustion basket 2.

  In order to produce a wax-like substance in the production apparatus described above, first, as the raw material A, a combustible, for example, crosslinked polyethylene alone, or a mixture of a crosslinked polyethylene and a polyolefin such as non-crosslinked or low-crosslinked polyethylene is used. A predetermined amount of the raw material A is charged onto the rooster 3 of the combustion basket 2 from the raw material charging hopper 6.

  Next, when the crosslinked polyethylene contained in the raw material A is ignited, the synthetic resin for producing the wax-like substance is thermally decomposed and melted, and the melt B is dropped from the rooster hole portion 3a and passes between the catalysts in the catalyst tank 4. Then, it falls into the reservoir tank T.

  At this time, the catalyst tank 4 and the receiving tank T gradually become deficient due to the disappearance of oxygen due to combustion of the highly crosslinked polyethylene, and the wax-like substance C thermally decomposed in the deficient oxygen state accumulates in the receiving tank T.

  As described above, the wax-like substance C that is melted and in a high heat state is partially vaporized in an oxygen deficient state to generate a flammable hot gas G. The hot gas G is sent into the combustion basket 2 through a communication pipe 9 provided between the reservoir tank T and the combustion basket 2.

  The communication pipe 9 is for efficiently sending the flammable hot gas G generated in the reservoir tank T into the combustion basket 2, and a plurality of the pipes 9 are located above and below the outer wall of the reservoir tank T. Each communication pipe 9 is provided with a pump 10 for sending the gas from the reservoir tank T to the combustion basket 2 in order to promote the delivery of the hot gas G. The hot gas G is mixed with the air introduced from the air introduction hole 2a of the combustion basket 2 in the combustion place of the raw material A sent into the combustion basket 2 and burned, and the melting of the raw material A is continued. . By configuring the apparatus in this manner, it is necessary to supply thermal energy at the time of start-up, but thereafter, thermal energy is supplied independently.

  In the present invention, as the raw material A, cross-linked polyethylene that has undergone thermal oxidation degradation is used. As a result, the wax-like substance C stored in the receiving tank T is generated as an oxidation type polyethylene wax.

OC wire (cross-linked polyethylene insulated wire for outdoor use) covered waste of cross-linked polyethylene is heat-treated at 150 ° C for 250 hours and then waxed in the process of pyrolysis, and the total acid number is measured by the method shown in JIS K5902. went. (Example 1)
For Examples 2 to 18 and Comparative Examples 1 to 5 shown below, various electric wires shown in Table 1 (OC-W electric wire is an abbreviation for water-tight outdoor cross-linked polyethylene insulated wire, CV cable is cross-linked polyethylene insulated cable) (EEA and EVA are the types of watertight fillers) were heat-treated at the temperature and time shown in the columns of thermal oxidation temperature and thermal oxidation time, and then the total acid value was measured by the method shown in JIS K5902.

In Table 1, “OC” in the types of wires is OC wire, “CV” is CV cable, OC-W (EVA) is OC-W wire using EVA watertight filler, OC-W ( EEA) represents OC-W electric wire using EEA watertight filler. Yield represents a good yield of 40% or more and a bad yield of less than 40% when the crosslinked polyethylene subjected to the thermal oxidative degradation treatment is waxed in the process of combustion pyrolysis.
In Table 1, it can be seen that an oxidized polyethylene wax with an acid value of 1 mg · KOH / g or more can be produced by heat treatment at 130 ° C or higher, and the acid value can be adjusted according to the heat treatment temperature, heat treatment time, and type of wire. You can also see that. In general, when the heat treatment temperature is low, a long heat treatment time is required, and when the heat treatment temperature is high, decomposition / carbonization proceeds and the yield decreases. Therefore, it is preferable to shorten the heat treatment time. For example, the acid value of OC-W (EEA) saturates at about 15 mg · KOH / g, but at a heat treatment temperature exceeding 200 ° C. and a heat treatment time exceeding 50 hours, the amount of recovered wax (carbonized by the carbonization of crosslinked polyethylene ( Yield) is reduced. It can also be seen that heat treatment at 150 to 180 ° C. using EEA OC-W as a raw material is effective for obtaining oxidized polyethylene wax having an acid value of 10 mg · KOH / g or more, which is in great demand.
From the above, it can be said that the heating temperature is 130 to 200 ° C. and the heat treatment time is about 24 to 1000 hours, more preferably 150 to 180 ° C., and the heating time is about 500 to 1000 hours.
As described above, according to the present invention, an oxidation type polyethylene wax can be easily produced by a simple treatment in which combustion thermal decomposition is performed after experiencing thermal oxidation degradation in advance.

FIG. 3 is a cross-sectional explanatory view of a main part showing a conventionally known combustion pyrolysis furnace used in the present invention.

Claims (4)

  In the method for producing a polyethylene wax having an acid value of 1 mg · KOH / g or more, the crosslinked polyethylene is preliminarily thermally oxidized and deteriorated, and then the thermally oxidized and deteriorated crosslinked polyethylene is subjected to a process of combustion and pyrolysis. A method for producing polyethylene wax.   The method for producing a polyethylene wax according to claim 1, wherein the heat treatment temperature for thermal oxidative degradation is 130 to 200 ° C.   The method for producing a polyethylene wax according to claim 1 or 2, wherein the heat treatment time for thermal oxidative degradation is 24 to 1000 hours.   The method for producing polyethylene wax according to any one of claims 1 to 3, wherein the cross-linked polyethylene is one using an OC electric wire, an OC-W electric wire, or a CV cable.

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