JPS61127744A - Stabilized polyolefin composition - Google Patents

Abstract

PURPOSE:To produce a polyolefin composition having excellent resistance to oxidative degradation in melt kneading or in practical use, by compounding a polyolefin with specific amounts of a specific phenolic compound and a phosphorous acid ester. CONSTITUTION:(A) 100pts.wt. of a polyolefin, preferably an ethylene homopolymer, a copolymer of ethylene and propylene, etc., a propylene homopolymer, or a copolymer of propylene and butene-1, etc. is compounded with (B) 0.01-1pt.wt. of a phenolic compound of formula I (R1 and R2 are 1-8C alkyl), e.g. tetrakis-[methylene-3-(3',5'-di-t-bytyl-4'-hydroxyphenyl)-p- ropionate]methane and (C) 0.01-1pt.wt. of a phosphorous acid ester compound of formula II, e.g. tetrakis(2,4-di-t-butylphenyl) 4,4'-biphenylene-di-phosphonite.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyolefin compositions. More specifically, the present invention relates to a polyolefin composition that is excellent in preventing oxidative deterioration of polyolefins during melt mixing and practical use.

Polyolefins have excellent processability, chemical resistance, and electrical properties, so they are widely used in the fields of home appliances, automobile parts, household goods, industrial materials, etc.

Generally, polyolefins are molded at a temperature higher than the melting point of the polyolefin, and the polyolefin undergoes oxidative deterioration due to the heat generated during melt mixing, resulting in scission or crosslinking of molecular chains of the polyolefin. Therefore, problems arise, such as a decrease in processability and a decrease in mechanical strength due to variations in the molecular weight of the polyolefin, as well as coloration and odor due to oxidative deterioration.

In addition, polyolefins, especially polyglopylene polymers,
Because the polymer contains tertiary carbon that is easily susceptible to oxidation,
There is a problem with heat oxidation resistance during practical use. For this reason, various phenol-based and phosphite-based antioxidants have conventionally been used singly or in combination for the purpose of preventing thermal oxidative deterioration of rainbow polyolefins during melt-kneading and during practical use.

However, polyolefin compositions containing only conventional phenolic antioxidants, such as low molecular weight phenolic antioxidants such as 2,6-di-t-butyl-P-cresol, have poor heat resistance during melt-kneading. Although the oxidative deterioration resistance, that is, the processing stability, is extremely excellent, when the molded product is made into a molded product, it is resistant to thermal oxidative deterioration during practical use, and the resulting molded product is discolored due to the antioxidant used. There is a problem of doing so. Furthermore, when a composition containing a high molecular weight phenolic antioxidant is used to form a molded article, the molded article exhibits remarkable resistance to thermal oxidative deterioration during practical use. There are problems with heat oxidative deterioration resistance, that is, processing stability, during cross-contact, oxidative deterioration during melting, and coloration caused by the high molecular weight phenolic antioxidant.

In addition, the composition formed by using the above-mentioned low molecular weight phenolic antioxidant and high molecular weight phenolic antioxidant in combination has excellent processing stability and heat oxidation resistance of the molded article during practical use. Although the deterioration resistance is excellent as mentioned above, there is almost no additive effect when used in combination, and on the contrary, as the amount of phenolic antioxidant is increased, the coloring of the obtained molded product becomes noticeable. There is a problem.

On the other hand, a composition formed by blending a phosphite-based antioxidant with a polyolefin has excellent processing stability. The problem of colorability of molded products is significantly improved.

However, when a composition containing the phosphite-based antioxidant alone is used as a molded article, there is almost no resistance to thermal oxidative deterioration during practical use, and although the composition is sufficiently satisfactory for practical use, do not have. Therefore, as a method of improving processing stability, resistance to thermal oxidative deterioration during practical use, and coloring property, it is possible to use a high molecular weight phenolic antioxidant and a phosphite ester antioxidant in combination. However, in such a combination system, three problems with the conventional technology are processing stability, thermal oxidative deterioration resistance of the molded product during practical use, and coloration caused by the antioxidant used. Simultaneous improvement is possible to some extent, but it is not yet sufficient. In particular, with regard to processing stability and thermal oxidative deterioration resistance in practical use, the mere combination of the high molecular weight phenolic antioxidant and the phosphite ester antioxidant does not provide sufficient mutual effect in preventing thermal oxidative deterioration. This is thought to be because.

The present inventors have conducted extensive research in order to solve the problems associated with the above-mentioned polyolefins by using the above-mentioned phenolic antioxidants and phosphite-based antioxidants alone or in combination.

As a result, a phenol compound represented by the following general formula ([] (hereinafter referred to as compound person)) and a phosphite ester compound represented by the following general formula (II) (hereinafter referred to as compound B) were added to the polyolefin. It has been discovered that a composition obtained by blending the polyolefins can solve the above-mentioned problems of polyolefins, and based on this knowledge, the present invention has been completed.

(In the formula, R, , and R each represent the same or different alkyl group having 1 to 8 carbon atoms.) As is clear from the above description, the purpose of the present invention is to improve processing stability and moldability. It is an object of the present invention to provide a polyoff foam composition which is excellent in improving heat oxidative deterioration resistance during practical use of molded articles and coloring properties caused by the antioxidant used.

The present invention has the following configuration.

For 100 parts by weight of polyolefin, the following general formula CI
) (hereinafter referred to as compound A) and a phosphite compound (hereinafter referred to as composition) represented by the following general formula [II] (wherein R1eR1 each has 1 to 8 carbon atoms) (Indicates the same or different alkyl groups.)

Examples of the polyolefin used in the present invention include homopolymers of α-olefins such as ethylene, propylene, butene-1, and pentene-1, porcelain/dumb copolymers, block copolymers, or mixtures of two or more of these. I can do it. In addition, copolymers of these α-olefins and vinyl acetate, acrylic esters, etc., or saponified products thereof, or copolymers of these α-olefins and unsaturated carboxylic acids or their anhydrides, or copolymers and metals. Examples include reaction products with ionic compounds.

Furthermore, a modified polyolefin obtained by graft polymerizing an unsaturated carboxylic acid or a derivative thereof to a polyolefin, or a mixture of the modified polyolefin and an unmodified polyolefin can also be used. Ethylene polymers such as ethylene homopolymer, ethylene butene-1 copolymer, and propylene/homopolymer, ethylene propylene/random copolymer, ethylene propylene/buty/-13 copolymer, propylene hexene butene Propylene-based polymers such as -13-element copolymers are particularly preferred.

An example of compound A used in the present invention is tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate comethane. Also, as compound B, Tetrakis (2,4-di-
t-butylphenyl)4,4'-biphenylene-di-7
An example of this is male 7 onite. The compounding ratio of these compounds and compound B is 0.01 to 10 parts by weight, preferably Q and O.
It is 1 to 0.5 parts by weight. If the amount is less than 0.01 xii part, the desired effect will not be fully exhibited, and although it is possible to add more than 1 part by weight, it is not only impractical but also uneconomical as no further improvement in the effect can be expected. be.

The composition of the present invention includes various additives that are normally added to polyolefins, such as phenol-based, thioether-based, phosphorus/acid ester-based antioxidants, light stabilizers,
Clarifying agent, nucleating agent, lubricant, antistatic agent, anti-drop agent, anti-drop agent, pigment, heavy metal deactivator (copper damage inhibitor)
, flame retardants, peroxides, dispersants or neutralizing agents such as metal soaps, and inorganic fillers (e.g. Merck, mica, clay, calcium carbonate, aluminum hydroxide, magnesium hydroxide, sulfuric acid), chlorium, zeolite. , asbeth, glass fiber calcium silicate, etc.) can be used in combination without impairing the object of the present invention.

The composition of the present invention is prepared by mixing predetermined amounts of each of the above-mentioned compounds and compound B as well as the above-mentioned various additives that are usually added to polyolefins in a conventional mixing device such as a Hensel mixer (trade name), a super mixer, a ribbon blender, etc. Mix using a Pan Bali mixer or the like, and melt-knead with a normal single-screw extruder, twin-screw extruder, roll, etc. at a temperature of 150°C to 300°C, preferably 180°C to 250°C.
It can be obtained by melt-mixing pelletizing at ℃. The obtained composition is used to produce a desired molded article by various molding methods such as injection molding, extrusion molding, and blow molding.

The composition of the present invention has excellent processing stability during melt mixing during the molding process, and there is no coloring caused by the antioxidant used, and molded products manufactured using the composition can be used in practical use. Because of its excellent resistance to thermal oxidative deterioration, it can be advantageously used in products in various molding fields. In addition, ethylene polymers tend to undergo crosslinking reactions when melted and mixed, and when the melted mixed material is formed into a film or sheet, there is a problem that fish eyes occur due to the high molecular weight components caused by the crosslinking reaction. Since the composition of the present invention exhibits an excellent effect in preventing crosslinking during melt crosslinking, a film or sheet using the composition of the present invention has an excellent appearance and shape with greatly suppressed occurrence of fish eyes.

In the present invention, the mechanism of action of the combined use of the compound B and compound B during melt mixing of polyolefin is not clear. However, although Compound A exhibits a remarkable effect on static thermal stability in the low-temperature region near the softening point of polyolefins, that is, in terms of thermal oxidative deterioration resistance in practical use, on the other hand, it exhibits a remarkable effect on the thermal oxidative deterioration resistance in the polyolefin melting temperature region. It is known that dynamic thermal stability, that is, processing stability, is relatively poor among phenolic compounds.

However, it has been found that when used in combination with Compound B, a surprising synergistic effect is exhibited that cannot be predicted from the combination of Compound B with other heptanols.

Furthermore, the reason why the composition of the present invention is excellent in thermal oxidative deterioration resistance during practical use is thought to be because the compound B used has a remarkable ability to regenerate oxidized compound storage.

The composition of the present invention has 1) superior thermal oxidative deterioration resistance and discoloration resistance during molding compared to known polyolefin compositions that use phenolic and phosphite ester compounds alone or in combination; Excellent. It is particularly excellent in thermal oxidative deterioration resistance, that is, processing stability and coloring prevention property when subjected to thermal history due to several times of melt-kneading at high temperatures. 2) When formed into a molded article, the molded article has significantly excellent resistance to thermal oxidative deterioration during practical use.

EXAMPLES The present invention will be specifically explained below with reference to Examples and Comparative Examples, but the present invention is not limited thereby.

The evaluation method used in Examples and Comparative Examples was as follows.

■) Processing stability: Measurement of the melt index (Ml) of the pellet obtained when an ethylene polymer is used as the polyolefin (according to JISK 67601c)
, Measurement of the melt flow rate (MFR) of the pellet obtained when a propylene polymer is used (JIS K
6758).

These are called the first YI and the first MPR.

n) Coloration prevention property: YI (Yell
Measurement of ownership Index (JIs K 7)
103).

The YI value at this time is called the first YI.

■) Heat oxidative deterioration resistance in practical use: Evaluated by open life test. That is, using the obtained pellet length 5
G... Width 251? l! , create a test piece with a thickness of 1 mm,
The test piece was placed in an open circulating hot air chamber whose temperature was adjusted to 150°C, and the time required for the test piece to completely deteriorate (tensile strength was 0).
The evaluation was made by measuring (in accordance with JIS K7212).

■) Resistance to thermal oxidative deterioration at high temperatures: The obtained pellets were melt-kneaded repeatedly at a melt-kneading temperature of 270°C, and the MI, MFR, and YI of the obtained pellets were measured.
I, 1st MFR, 7th LYI. (L indicates the number of times melt-kneading is repeated.) a) When the polyolefin used is an ethylene polymer, it was evaluated based on the values of the cylinder FLMI, the rLYI, and the MI retention rate according to the following formula.

b) MT retention rate = rLM I/MI of raw material ethylene polymer powder The closer the MI retention rate is to 1.01c and the smaller the 3rd YI is, the better the thermal oxidative deterioration resistance at high temperatures is.

Anti-crosslinking property: Evaluated by fish eye measurement.

Using a T-die extruder, the cylinder temperature is 190℃~2
50℃, die temperature 250'C1 resin pressure 250kg/c
A sheet with a thickness of 0.4 mm is created using rIIG, and the diameter of 1000 cttl of this sheet is 0.4 mm. : 3++x or more fish eyes were detected and counted. The smaller the fisheye value, the less high molecular weight components are produced and the better the crosslinking prevention properties are.

In other words, it shows that it has excellent thermal oxidation deterioration resistance at high temperatures.

b) When the polyolefin used is a propylene polymer, evaluation was made based on the numerical values of cylinder 2 MPR, 2nd YI and ΔMPR = 2nd MFR - 1st MPR ΔYI = 2nd YI - 1st YI The values of ΔMPR and ΔYI were evaluated.

The smaller these values are, the better the thermal oxidative deterioration resistance at high temperatures is.

Examples 1-2, Comparative Examples 1-15 As a polyolefin, MI (load 2 at 190°C
．． To 100 parts by weight of powdered Ziegler-Rokutsuta ethylene homopolymer (discharge amount of molten resin per 10 minutes when adding 16 kg) 17.51)/1 G of tetrakis [methylene] listed in Table 1 as Compound A, -3-(3', 5'-
di-t-butyl-4'-hydroxyphenyl)globionate]methane, compound B as tetrakis(2,4-
Predetermined amounts of di-t-butylphenyl) 4,4'-biphenylene-di-7m, onite, and other additives were placed in a Hensel mixer (trade name), mixed, and then extruded using a single screw having a diameter of 40 m. The mixture was melt-kneaded and pelletized using a machine at 200°C. Also, as Comparative Examples 1 to 15, MI was 17.5.
Predetermined amounts of each of the additives listed in Table 1 were mixed, melt-kneaded, and pelletized in the same manner as in Examples 1 and 2 to 100 parts by weight of powdered Ziegler-Natsuta ethylene homopolymer of J/10 min.

Using the obtained pellets, processing stability and anti-coloring properties were evaluated using the test method described above.

In addition, the fish eye measurement was performed at a thickness of 0.4B under the above conditions.
A medium die sheet was prepared and used for measurement.

In order to examine the thermal oxidative deterioration resistance at high temperatures, the pellets obtained above were again melt-kneaded and pelletized using a single-screw extruder with a diameter of 40 iz at a melt-kneading temperature of 270° C., and this process was repeated three times.

Each time the pellets were melted and kneaded, MI and Yl of the obtained pellets were measured again using the method described above, and the MI retention rate (value for the fourth YI) was calculated.

These results are shown in Table 1.

Example 3, Comparative Examples 16 to z6 Polyolefin/MFR (discharge amount of molten resin in 10 minutes when applying a load of 2.16 kg at 230'C) 6. Ofi / 100 parts by weight of powdered propylene resin homopolymer for 10 minutes was added with the compounds listed in Table 2 and compound B (the same compound used in Examples 1 and 2).
Example 1
The mixture was mixed, melt-kneaded, and pelletized in the same manner as in 2.

Further, as Comparative Examples 16 to 26, MFR was 6.0. F/10
In Examples 1 to 2, predetermined amounts of each of the additives listed in Table 2 were blended with 100 parts by weight of powdered propylene homopolymer.
Pellets were obtained in the same manner as above.

The test pieces used in the open test were prepared by injection molding the obtained pellets at a resin temperature of 250°C.

Using the obtained pellets and test pieces, processing stability, anti-coloring properties, and oven life tests were evaluated using the test methods described above.

In order to examine the thermal oxidative deterioration resistance at high temperatures, the pellets obtained above were again melt-kneaded and pelletized at a temperature of 270° C. using a single-screw extruder with a diameter of 40°. The MFR and YI of the obtained pellet were measured again using the method described above, and ΔM
FR and ΔYI were calculated.

These results are shown in Table 2.

The compounds and additives according to the present invention shown in Tables 1 and 2 are as follows.

Compound A (high molecular weight phenolic compound): Tetrakissu[methylene-3-(3',5'-di-t-butyl-4
'-hydroxyphenyl)gropionate] methane low molecular weight phenolic additive 1; 2,6-di-t-
Butyl-P-cresol Low molecular weight phenolic additive 2; 4,4'-butylidenebis(3-methyl-6-t-butylphenol) High molecular weight phenolic additive 1; Leuctadecyl-β
-(4'-hydroxy-3', 5'-di-t-butylphenyl)probionate high molecular weight phenolic additive 2; tris(3,5-di-
t-Butyl-4-hydroxybenzyl)in cyanurate compound B; Tet2kis(2,4-di-t-butylphenyl)4.4'-biphaate-di-phosphite phosphite additive x ;tls(2,4-di-t
-butylphenyl) phosphite phosphite ester additive 2: di-stearyl pentaerythritol 7 osphite Ca-81, "Calcium stearate" As shown in Table 1, Examples 1 and 2 are suitable for the present invention. Comparing Example 1 with Comparative Examples 1 to 5, it can be seen that Example 1 is superior in both processing stability and coloring prevention properties. In particular, the MI retention rate, which indicates thermal oxidative deterioration resistance at high temperatures, that is, crosslinking prevention property, was 0.95 in Example 1, and there was almost no deterioration in processing stability even after four thermal cycles, which was caused by the crosslinking reaction. It can be seen that the fish eye value is also small.Among Comparative Examples 1 to 5, the MI retention rate of Comparative Example 1 using BIT (phenolic additive 1), which is most commonly used, is 0.83. It can also be seen that the composition of the present invention has extremely excellent processing stability.

Furthermore, when comparing Comparative Examples 6 to 8 (combined system of compound storage and low molecular weight phenol additive or combined system of high molecular weight phenol additive and low molecular weight phenol additive) and Example 1, Comparative Example 6 ~8 is MI retention rate, 1st YI ~ 4th
Both the YI value and the fisheye value are those of Example 1.
It can be seen that the heat resistance and oxidation deterioration prevention property at high temperatures is inferior to that of .

In addition, Comparative Examples 9 to 1) are examples in which only Compound B or a phosphite additive was used alone without using a compound or a phenol additive, but the blending amount was 0.1
In addition to the large number of polymerized parts, the anti-coloration property is superior to that of Example 1, but the difference is slight and not large enough to cause a practical problem. However, Comparative Examples 9 to 1) had higher MI retention and fish eye values than Example IK, and were not effective in preventing the crosslinking reaction of the ethylene homopolymer used. In other words, it can be seen that the thermal oxidative deterioration resistance at high temperatures is poor.

However, in Example 1, it can be seen that a significant mutual effect was obtained by combining Compound A and Compound B.

Comparative Examples 12 to 15 are examples of combination systems in which either Compound A or Compound B is a compound related to the present invention, and the other is a conventionally used compound. Compared to Example 1, the thermal oxidative deterioration resistance at high temperatures is inferior. This means that the composition of the present invention
This shows that the composition is superior in all respects to compositions prepared in combination with conventionally known additives.

In addition, in Example 2, the compound location and compound B content used in Example 1 were reduced to about 2/2, but compared to Comparative Examples 1 to 15, except for Comparative Example 12, the heat oxidation resistance is excellent. Example 2 and Comparative Example 12 have almost the same resistance to thermal oxidative deterioration, but considering that the amount of stabilizer added in Example 2 is about 'A' smaller, the composition of the present invention is much better. It turns out that it is excellent.

Table 2 summarizes the results when a propylene polymer was used as the polyolefin. Example 3 is an example of a composition in which Compound A and Compound B are blended in parts by weight of each O and OS, but it has better thermal oxidative deterioration resistance at high temperatures, coloring prevention property, and practical use than any of Comparative Examples 16 to 26. It was found that both of the thermal oxidation resistance and deterioration resistance were excellent, confirming the remarkable effects of the composition of the present invention.

Patent applicant: Chisso Co., Ltd. Representative Patent Attorney Yatabe Sasai Same as above
Continued correction by Katsuhiko Nonaka
Book February 72, 1985

Claims (1)

[Scope of Claims] (1) A phenolic compound represented by the following general formula [I] (hereinafter referred to as compound A) and a phosphorous acid represented by the following general formula [II], based on 100 parts by weight of polyolefin. Stabilized polyolefin composition containing 0.01 to 1 part by weight of each ester compound (hereinafter referred to as compound B) ▲ There are mathematical formulas, chemical formulas, tables, etc. There are tables, etc. ▼ [II] (However, in the formula, R_1 and R_2 each have 1 to 8 carbon atoms.
represents the same or different alkyl groups. ) (2) Compound A is tetrakis[methylene-3-(3',5'-
di-t-butyl-4'-hydroxyphenyl)propionate]methane and compound B, tetrakis(2
, 4-di-t-butylphenyl) 4,4'-biphenylene-di-phosphonite. (3) The polyolefin is an ethylene homopolymer or a copolymer of ethylene and propylene, butene-1, hexene-1, octene-1, or a mixture of two or more of these, or The polyolefin composition according to any one of item (2). (4) The polyolefin is a propylene homopolymer or a copolymer of propylene and ethylene, butene-1, hexene-1, octene-1, or a mixture of two or more of these, or The polyolefin composition according to any one of item (2).