JPS5815509A - Production of ethylene/vinyl acetate copolymer for hydrocarbon fuel oil - Google Patents

Abstract

PURPOSE:To obtain the titled copolymer excellent in pour point depressing effect and low-temperature filtrability, in high yields, by copolymerizing ethylene with vinyl acetate in the presence of a mixed solvent consisting of tert-butyl alcohol and an aliphatic or alicyclic hydrocarbon or an ester. CONSTITUTION:An ethylene/vinyl acetate copolymer is obtained by charging an autoclave with a mixed solvent consisting of 0-60wt% aliphatic hydrocarbon, alicyclic hydrocarbon or a fatty acid ester of an aliphatic alcohol (e.g., n- heptane, cyclopentane, methyl acetate) and 100-40wt% tert-butyl alcohol and vinyl acetate, pressurizing the autoclave with ethylene and copolymerizing the reaction mixture at 130-180 deg.C. The produced copolymer is added to an oil such as light naphtha, heavy naphtha or crude oil, in an amount of 50-3,000ppm to prevent the viscosity increase of oil with a termperature decrease and the deposition of paraffin in oil.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing an ethylene-vinyl acetate copolymer suitable as a low-temperature flow property improver for hydrocarbon fuel oils.

Distillate oils and heavy oils such as light naphtha, heavy naphtha, kerosene, and gas oil, as well as crude oil, which is the starting material for these oils, may be produced in cold regions, or if refining is carried out in the production region, or in pipelines. When transporting oil, the viscosity increases as the temperature of the oil drops, reducing transportation capacity, or the paraffin contained in the oil precipitates, causing blockages in pipes, pulp blockage, and filtration systems. This causes complications such as blockage.

As one method for solving these problems, various additive resins have been developed and used. For example, special public service in Showa 59
-20069 discloses a copolymer of ethylene and a vinyl ester monomer having 3 to 5 carbon atoms per molecule,
Ethylene-vinyl acetate copolymers are useful as additive resins, such as the ethylene-vinyl acetate copolymer obtained under specific conditions, which is described in Special Publication No. 1@4+-16755. However, there are no methods for producing these ethylene-vinyl acetate copolymers, i.e., benzene, toluene, xylene, n-hebutane, n-hexane, cyclohexane, cyclopentane, methyl acetate, ethyl acetate, acetone, dioxane, methanol, ethanol, propane. The method of copolymerizing ethylene and vinyl acetate with a free radical catalyst at a temperature of 168 to 171°C using a solvent such as butanol has excellent pour point depressing properties and low-temperature filtration properties.
Moreover, an ethylene-vinyl acetate copolymer cannot be obtained with a high reaction yield.

However, in order to solve this problem, the present inventors have found that only by using together hydrogen or fatty acid esters of aliphatic alcohols, alicyclic hydrocarbons, and (bl tertiary butyl alcohol) in a specific ratio, the pour point It was discovered that an ethylene-vinyl acetate copolymer can be obtained with excellent descending properties and low-temperature filtration properties, and with a high reaction yield, leading to the completion of the present invention.

In the method for producing the ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) of the present invention, a solvent and vinyl acetate are charged in whole or in part into a stainless steel autoclave equipped with a stirrer, and the autoclave is pressurized with ethylene. When ethylene is consumed in the reaction and the pressure drops below a predetermined pressure, ethylene may be reintroduced. A predetermined amount of the polymerization catalyst may also be added at the beginning of the reaction, or a predetermined amount may be added in portions.

Next, the individual conditions will be explained in detail. The proportion of (a) aliphatic hydrocarbon or fatty acid ester of aliphatic alcohol or alicyclic hydrocarbon is 0 to 60% by weight, preferably 0 to 50% by weight. (bl tertiary butyl alcohol is 100% by weight) ~40% by weight, preferably 1lt1.00~
It is 50% by weight. If the ratio of the solvents (a) and (b) deviates from the above ratio, EVA with excellent pour point depressing properties, low-temperature filtration properties, and a good reaction yield cannot be obtained.

Examples of the aliphatic hydrocarbons include n-heptane, n-hexane, n-octane, and isooctane, and examples of fatty acid esters of aliphatic alcohols include methyl acetate,
Examples include ethyl acetate and butyl acetate, and examples of alicyclic hydrocarbons include cyclopenkune and cyclohexane. A predetermined amount of these solvents F′i may be used at a rate of 1 to 6 times the amount of the copolymer obtained at the initial stage of the reaction, or they may be added in successive equal amounts in portions during the reaction. Any method is fine.

As the polymerization catalyst, known catalysts such as benzoyl peroxide, acetyl peroxide, lafuroyl peroxide, dicumyl peroxide, di-tert-glutyl peroxide, and azobisisobityronitrile are used, and the amount used is determined by the amount obtained. An appropriate amount is selected from a range of 1 to 20% by weight based on the copolymer.

The polymerization temperature is 150 to 180°C, preferably 150°C.
-160°C.

EVAH in the present invention, ethylene content is 69 to 79
weight% and the intrinsic viscosity is 111 to 0.4 (dg/yS3
(0°C, benzene), preferably in the range of 0.15 to 0.20; if the ethylene content and intrinsic viscosity are outside this range, both pour point depressing properties and low-temperature filtration properties are excellent. It will not become something.

The proportion of the EVA to be blended into the hydrocarbon fuel oil is 50 to 5000 ppm, preferably #: t50, relative to light naphtha, heavy naphtha, kerosene, light oil, heavy oil, crude oil, etc.
It is within the range of 0 to 2,000 ppm, and exhibits excellent pour point depressing properties and low-temperature filtration properties particularly in the range of 100 to 1,000 ppm for light oil.

Further, when using the EVA, other commonly used additives, antioxidants, other pour point depressants, viscosity index improvers, etc. may be added depending on the intended use.

Next, the present invention will be specifically explained with reference to Examples.

In examples, "parts" and "%" are based on weight unless otherwise specified.

Example 1 75 parts of tertiary butyl alcohol, 5 parts of ethyl acetate, and 25 parts of vinyl acetate were placed in an 11-volume autoclave.
After replacing the gas phase with ethylene gas, the temperature was raised to 140°C and ethylene was charged to a pressure of 70 G at 140°C. Then 50 parts of tertiary butanol and 50 parts of ethyl acetate
1/2 of a mixed solvent, 75 parts of vinyl acetate, and 6 parts of azobisisobutyronitrile (AIBN) were uniformly charged over 6 hours. The obtained EVA was 280 parts and its ethylene content was 75%. In addition, the intrinsic viscosity is 015 C.
dl/f, 30°C, benzene).

Examples 2 to 4 In Example 2, tertiary butanol 40%, ethyl acetate 60%
% mixed solvent, in Example 6 tertiary butanol 70%,
EVA was obtained in the same manner as in Example 1 except that a mixed solvent of 50% ethyl acetate was used, and in Example 4, tertiary butanol was used as the solvent. The results are shown in Table 1.

Control Examples 1 to 5 EVA was obtained in the same manner as in Example 1 except that benzene was used in Control Example 1, n-hexane was used in Control Example 2, and ethyl acetate was used in Control Example 6.

The results are shown in Table 1.

Next, distillate oil obtained from Middle Eastern crude oil (90% distillate 350
℃, 50% distillation (242℃), 150 ppm of EVA of the above example and control example was added, and the PP (Pour P
o1nt) was measured according to JIS-2269, and CFPPCCo1d Fter Plugging
Point) 1. It was measured by the method specified in P. 509/76. The results are also listed in Table 1. As is clear from these, the polymer yields of the present invention are both high and excellent in reducing PP and CFPP.

Abbreviation t-BuOH: tertiary butyl alcohol A c o E
t: ethyl acetate

Claims (1)

[Claims] Ethylene and vinyl acetate (0 to 60% by weight of 11 aliphatic hydrocarbons or fatty acid esters of aliphatic alcohols or alicyclic hydrocarbons, (100 to 40% by weight of tertiary butyl alcohol) 1. A method for producing an ethylene-vinyl acetate copolymer for use in adding hydrocarbon fuel oil, which comprises copolymerizing in the presence of a mixed solvent consisting of the following proportions.