JPS5968307A - Cross-fractionation of ethylene/alpha-olefin copolymer - Google Patents

Abstract

PURPOSE:To obtain fractions such having a sharp MW distribution and a sharp composition distribution and so suitably usable in quality control or the like, by cross-fractionating the titled copolymer with a p-xylene/butyl cellsolbe solvent in a specified manner. CONSTITUTION:An ethylene/alpha-olefin copolymer to be tested is used in a state in which it is supported on a carrier (e.g., diatomaceous earth). In step i, the above copolymer is placed in a column and then fractionally extracted with a xylene/ cellusolve solvent having the composition ratio varied continuously within the range of 0/100-100/0 (volume ratio), while the extraction temperature is maintained constant at a temperature of 110 deg.C-b.p. of xylene (fractionation on the basis of molecular weight). In step ii, the individual fractions are placed in separate columns and the fractionally extracted with a xylene/cellosolve solvent having a constant composition ratio within the range of 60/40-100/0, while the temperature is varied from room temperature to 130 deg.C (fractionation on the basis of chemical composition). The above procedures may be performed in reversed order (ii) (i).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cross-fractionating ethylene/σ-olefin copolymers.

A copolymer of ethylene and σ-olefin having 3 or more carbon atoms, called linear low-density polyethylene (L-Ll:1PIj), is a copolymer of ethylene and σ-olefin having 3 or more carbon atoms, which is a copolymer of conventional high-density low-density polyethylene (old)-
LD + 4B) to mechanical strength (tensile strength, tear strength, H5gy strength, heat resistance, environmental stress cracking resistance)
r-: scp, ), has excellent optical properties, etc., so I(
P-L, D It is expected to replace PTi+, and is particularly suitable as a material for coating films, injection molded products, steel pipes, and electric wires. On the other hand, polymeric substances do not necessarily consist of uniform molecular species; copolymerized polymers such as ethylene/α-olefin copolymers have a distribution in two aspects: molecular weight and chemical composition. are doing. It is a well-known fact that the mechanical strength and moldability of copolymer polymers are greatly influenced not only by their molecular weight and chemical composition, but also by their distribution.

Regarding ethylene ° (l-olefin copolymers, not only the molecular weight and chemical composition but also the distribution is specified),
There is an ethylene/σ-olefin copolymer shown in Japanese Patent No. 26809, but in any case, its distribution is only related to molecular weight. However, as mentioned above, it is known that the physical properties of copolymer polymers are influenced not only by the molecular weight distribution but also by the chemical composition distribution (hereinafter simply referred to as composition distribution). - There are almost no reports on the classification of olefin copolymers based on their chemical composition, and even more so, there are no known reports that define the two factors of molecular weight distribution and composition distribution.

Therefore, in order to control or improve the quality of copolymer polymers such as ethylene/a-olefin copolymers, the present inventors need to understand not only the molecular weight and chemical composition, but also their distribution. The present invention was arrived at as a result of investigating the development of classification and composition separation methods.

Zunawaji The present invention utilizes ethylene coated on a carrier.
Packed into an a-olefin copolymer column, (A)
The column extraction humidity was kept constant at an arbitrary temperature within the range of 1106 Cy, below the boiling point of c-p-xylene, and the composition ratio of the mixed solvent of p-xylene and butyl cellosolve was O/1.
00 to 101110 (volume 1i ratio), or CB) T) - The composition ratio of the mixed solvent of xylene and butyl cellosolve is changed to 60
Using a mixed solvent with a constant composition ratio within the range of /40 to +0010 (volume ratio), the column extraction temperature was varied from room temperature to 130 °C.
After being separated by one of the following methods, each fraction is individually coated again into a single body and filled into a tube ram.
This invention provides a cross-fractionation method for ethylene/σ-olefin copolymers, which is characterized in that the remainder is subsequently fractionated using a residual method.

The ethylene/α-olefin copolymer that can be applied to the method of the present invention refers to a transition metal catalyst, such as a highly active titanium catalyst component formed from a magnesium compound and a titanium compound, and a catalyst consisting of an f-engine aluminum/ram compound. It is obtained by copolymerizing ethylene and α-olefin by various methods such as slurry polymerization, gas phase polymerization, and high-temperature solution polymerization using a so-called medium-low pressure method.

Examples of the σ-auxiliary olefin copolymerized with ethylene in the ethylene/σ-A reflex copolymer include propylene, 1-butene, 1-pentene, 1-hexene, 4-
Methyl-1-pentene, 1-octene, 1-decene, 1
-Tetradecene, 1-octadecene with 3 to 1 carbon atoms
8 α-olefins can be mentioned. These α
- A combination of two or more olefins may be used.

In order to separate the ethylene/α-olefin copolymer by the method of the present invention, it is necessary to coat the carrier with the ethylene/α-olefin copolymer in advance. The carrier is not particularly limited as long as it is insoluble in p-xylene and butyl cellosolve, but generally diatomaceous earth,
Glass beads, steel balls, etc. are suitable. There are various known methods for coating the carrier with the ethylene/α-olefin copolymer, such as dissolving the ethylene/α-olefin copolymer in a certain mixed solvent such as p-xylene and butyl cellosolve, and then evaporating the solvent. A method of drying the ethylene/σ-olefin copolymer on a carrier, and a method of adsorbing the ethylene/α-olefin copolymer onto the carrier by lowering the temperature of the solution to around room temperature. Can be mentioned.

Ethylene α- coated on the carrier by the above method
After filling the column with the olefin copolymer, the following two steps are carried out.
(A) column extraction temperature of 110'C to below the boiling point of p-xylene, preferably 115 to 1,');
The composition ratio of the mixed solvent of p-xylene and butyl cellosolve is kept constant at an arbitrary temperature within the range of 5' (:
(T3) A method of extracting by continuously changing the volume ratio in the range of 100 to 10010 (volume ratio), and (T3) 1 of p-xylene and butyl cellosolve.
The composition ratio of the combined solvent is /10/40 to 10010 (volume 1), preferably 7 (J/30 to 90/Irl
, a method of extraction using a mixed solvent with a constant composition ratio, particularly preferably within the range of 75/25 to 85/15, and continuously changing the column extraction temperature from room temperature to 130'C;
After fractionating by one of the following methods, each fraction is individually coated on a carrier again by the above method, and then fractionated by the remaining methods. That is, no matter which combination of (AJ method-(B) method or (B) method-(A) method) is used for fractionation, the fractionated products obtained are the same.

In method (A), if the column extraction temperature is less than 110°C, compositional fractionation will occur, which is undesirable.

That is, in method (Δ), when the column extraction temperature is less than 110° C., the results are similar to method (B). On the other hand, when the temperature exceeds the boiling point of p-xylene, p-
Xylene boils and causes channeling, making it impossible to extract satisfactorily. In addition, the composition ratio of the mixed solvent of p-xylene and butyl cellosolve is continuously changed within the range of 0/100 to 10010 (volume ratio). It can be selected as appropriate depending on the molecular weight and composition ratio of the target ethylene/α-olefin copolymer, but generally p-xylene or a certain mixed solvent of p-xylene and butyl cellosolve is continuously added to butyl cellosolve. It is preferable to change the stiffness continuously. Incidentally, the fractionation according to method (A) is a method of selectively fractionating the ethylene/α-olef/r-silicone copolymer based on its molecular weight.

In method (13), if a mixed solvent of p-xylene and butyl cellosolve is used in which the volume ratio of p-xylene is less than 60, the extraction temperature range will be narrowed, which is not preferable for fractionation operation-1. The mixed solvent composition ratio of p-xylene and butyl cellosolve is 75/25 to 85.
A range of /15 is particularly preferable because the extraction temperature range is appropriate for fractionation operations, and the solubility of the extract is good and clogging in the column can be prevented. When performing column extraction, the column extraction humidity changes continuously from room temperature to 130°C, but the temperature is divided into several stages from room temperature to 130°C in advance and temporarily maintained at this temperature. Good too. Incidentally, (fractionation by the BJ method is a method in which fractionation based on the chemical composition of the ethylene/α-auxiliary olefin copolymer is selectively carried out).

By cross-fractionating the fin copolymer using the method of the present invention, it is possible to obtain a fractionated product with a narrower molecular weight distribution and composition distribution than ever before. It can be useful for more accurate quality control or quality improvement of olefin copolymers.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these embodiments in any way as long as it goes beyond the gist of the invention.

Example 1 Bakelite 73, an ethylene-butene-1 copolymer
44 blend (manufactured by Union Carbide: MrrR=
2.27g/lomi, ns density = 0.925g
/Cm3) cross separation results will be described below. In this example, after performing molecular weight fractionation by the method of
This fractionated product was further subjected to compositional fractionation by the method (B).

Molecular weight fractionation is carried out by known methods (e.g. p, s.

FranciS, et al, J, Po1. ym
Ernci, 31, 453 (1958 piece) as follows. After dissolving 50 g of the polymer in p-xylene 84, butyl cellosolve 2e, and 10 g of 2,6-diterthyalphylbarak 1/sol at 130°C, 1.5 kQ of celite (diatomaceous earth) was added. The above mixture was stirred and allowed to cool naturally to room temperature for 4 hours to ink the polymer onto the surface of Celite. After filling a cylindrical column with Celite containing this solvent, the solvent in the column was drained. Replaced with butyl cellosolve.Futyl cellosolve was not transferred or flowed out into the entire tunorum.
The temperature inside the horn ram was raised to 120'C. After the column temperature was constant at 120°C, by continuously increasing the amount of p-xylene in the solvent transferred to Noarum,
Each fraction was obtained from the effluent. Each fractionated category was precipitated with methanol, separated by P, and dried for use in the following operations. Table 1 summarizes the molecular weight fractionation results. In the table, x ('v) is the weight fraction of each fractionated category. It is the cumulative weight fraction subtracted from .The intrinsic viscosity [η] is the value measured in decalin at 135°C.The molecular weight was measured by the G I-'C method (gel permeation chromatography) as follows. Measured under the following conditions.

Equipment: 150C model made by Tsusai-Taz Co., Ltd. Power: q゛SKOIau-6 (6mmφX60
(1mm) Medium: ODCB Temperature: 135°C Flow rate: 1. Ome/min Injection concentration' 7.0In+! :/20m// 0DCB
((:'p, human capacity 400 pl) 1.6. Column elution volume was calibrated by the universal method using standard polystyrene manufactured by Toyo Soda Co., Ltd. and Pressure Sunmical Rei. In addition, the branch per 1000 c in the table The number was determined by IT (measurement) according to a conventional method.

From the results in Table 1, L L D P by method (A)
It is clear that the effect of molecular weight fractionation is significant in the fractionation of E.

Next, from among the classification categories obtained by the above method, the second.
Using the 4th, 6.8th, and 10th sorting sections, separation was carried out according to the method (B) described below. Separate 5g of p-xylene 1,2e, butyl cellosolve O0
Filter C and 1.5 g of 2.6-dicushialbutyl-valercresol with 130" (after dissolving in 'i', Cellai)
2750g was added. The mixture was allowed to naturally cool to room temperature while being stirred, and the separated sections were coached onto a Celite surface. This solvent-containing Celite was packed into a cylindrical column. After that, a mixed solvent of 80/20 (volume ratio) of l)-xylene and butyl cellosolve, which has the same solvent composition as the coating solvent, is transferred into the column and flowed out, and the crystallinity in the column is checked in the chamber. The temperature was raised in appropriate steps from the crystalline temperature to 120°C.The fractions obtained in each temperature range were reprecipitated in methanol, then separated and dried.

The classification results for each classification category are summarized in Tables 2-B.

Based on the results in Tables 2 to B, the relationship between elution humidity and ethylene content for each fractionation category was plotted in FIG.

From the results shown in Figure 1, if the fractionation is carried out using the CB method, there is a one-to-one relationship between the elution temperature and the ethylene content, regardless of the molecular weight. In order to clarify this fact more clearly, the weight average molecular weight and the number of branches per 1000 c of each fractionation are plotted in Figure 2. Therefore, L L D
l) Regarding R, molecular weight fractionation is performed by the method of France) and composition fractionation is selectively performed by the method of (F3). l
I understand that. That is, it can be seen that the polymer can be cross-fractionated by combining the method (A) and the method (B).

Example 2 According to Example 1, ethylene octene-1 copolymer Dowlex 61500-49 (manufactured by Dow Chemical Company: MrrR==1.29 g/10 m1n, density=
Table 7 summarizes the molecular weight fractionation results by the method of 〇) in which cross-fractionation of 0.929 g/('II) was performed.

The results of compositional classification of the 2.4th, 6.8th and 10th classification categories from Table 7 by method (13) are summarized in Tables 8-12. The relationship between the weight average molecular weight and the number of branches per 1000C for each fractionation section is plotted in FIG. It is clear from Figure 5 that the polymer can be cross-fractionated by combining the method (A) and method (B), the same as in Example 1.

[Brief explanation of drawings]

Figures 1 and 2 show the composition fractionation results of the molecular weight fraction of Haechlite 7344 ferlend.
[Product σ] Please indicate the results of composition separation.

Claims (1)

[Claims] (1) A column is filled with an ethylene/α-olefin copolymer coated on a carrier, (A) the column extraction temperature is kept constant at any temperature within the range of 110°C to below the boiling point of p-xylene; p-
The composition ratio of the mixed solvent of xylene and butyl cellosolve is 0.
(B) A method in which the composition ratio of p-xylene and butyl cellosolve is kept constant within the range of 60/40 to 10,010 (volume ratio). After fractionation by one of the following methods: using a mixed solvent with a different composition ratio and continuously changing the column extraction temperature from room temperature to 130°C, each fraction is individually re-coated onto a carrier. 1. A cross-fractionation method for an ethylene α-olefin copolymer, characterized in that the ethylene α-olefin copolymer is packed in a column and then fractionated by a residual method.