JPS62135550A - Stabilized polyolefin composition - Google Patents

Abstract

PURPOSE:To obtain a polyolefin compsn. having excellent resistance to deterioration by oxidation during melt kneading and practical application, by blending a polyolefin with a phenol compd. and a phosphite compd. CONSTITUTION:A polyolefin compsn. is obtd. by blending 100pts.wt. polyolefin with 0.01-1pt.wt. phenol compd. (A) of formula I and 0.001-1pt.wt. phosphite compd. (B) of formula II. In the formulas, R1, R2, R3, R4 are each H, a 1-8C alkyl. An example of the compd. A is 1,2,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4- hydroxybenzyl)benzene. An example of the compd. B is bis(2,4,-di-t-butylphenyl)- pentacrythritol diphosphite.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to stabilized polyolefin compositions. More specifically, the present invention relates to a polyolefin composition that is highly resistant to oxidative deterioration of polyolefin during melt mixing and practical use.

Polyolefins have excellent processability, chemical resistance, electrical properties, and economic efficiency, so they are used in the home appliances, automobile parts, and other fields.
Widely used in the household goods and industrial materials fields.

[Conventional technology]

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 during melt-kneading, causing scission or crosslinking of the molecular chains of the polyolefin. Therefore, problems such as a decrease in processability due to crosslinking of the polyolefin, a decrease in mechanical fir due to a decrease in the molecular cap, and coloring and odor due to oxidative deterioration occur.

In addition, polyolefins, especially polypropylene-based single units,
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, phenolic and phosphorus antioxidants have been used individually or in combination for the purpose of preventing thermal oxidative deterioration during bath melt kneading and practical use of polyolefins.

[Problem that the invention seeks to solve]

However, compositions containing only conventional phenolic antioxidants and low molecular weight phenolic antioxidants such as 2.6-di-t-butyl-p-cresol have poor heat resistance during melt mixing. Although the oxidative deterioration resistance (hereinafter referred to as thermal processing stability) is extremely ambiguous, the thermal oxidative deterioration resistance (hereinafter referred to as thermal stability in practical use) of a molded article in practical use is extremely unclear. ) and that the resulting molded product is colored due to the antioxidant used. Furthermore, compositions containing only high-molecular weight phenolic antioxidants have excellent thermal stability during practical use when molded products are made from the composition. There are problems with the processing stability and the coloring property caused by the phenolic antioxidant in the polymer cap.

In addition, the composition formed by using the above-mentioned low molecular weight phenolic antioxidant and high molecular weight phenolic antioxidant in combination has a high thermal processing stability and a molded article that can be used in practical use. Although the thermal stability of phenolic antioxidants is excellent as mentioned above, there is almost no synergistic effect when used in combination, and on the contrary, as the blending ratio of phenolic antioxidants increases, the resulting molded products become noticeably colored. There are some problems.

On the other hand, a composition made by blending only a phosphorus antioxidant with a polyolefin has excellent thermal processing stability, and it is difficult to produce molded products using a composition made by blending the above-mentioned phenolic antioxidant. The problem of colorability is significantly improved. However, when the composition of the phosphorus-based antioxidant is used alone, the thermal stability of the molded product during practical use is hardly recognized, and it is difficult to believe that it is sufficiently satisfactory for practical use. I can't say that.

Therefore, as a method of improving thermal processing stability, thermal stability during practical use, and colorability, it is considered to use a high molecular weight phenolic antioxidant and a phosphorus antioxidant in combination.

However, in such a combination system, it is difficult to simultaneously improve thermal processing stability, thermal stability during practical use, and 3':4 coloring properties caused by the antioxidant used, which are the problems of the conventional technology. It is possible, but not yet sufficient. In particular, regarding thermal processing stability and thermal stability in practical use, the synergistic effect of the thermal oxidative deterioration prevention effect is insufficient if the high molecular weight phenolic antioxidant and the phosphorus antioxidant are used together. it is conceivable that.

In order to solve the problems related to the above-mentioned polyolefins using the above-mentioned 7-enol antioxidants and phosphorus-based antioxidants alone or in combination, the Ministry of the Invention has previously filed a patent application filed in Japanese Patent Application No.
In No. 249184, a composition was proposed in which a specific phenolic antioxidant and a phosphorous antioxidant made of a specific 7-osphonite compound were used together, but the authors were not satisfied with this and conducted further research. As a result, a phenolic compound represented by the following general formula (1) (hereinafter referred to as compound*J) and the following general formula (I
discovered that a composition containing a phosphite compound represented by t) (hereinafter referred to as compound B) can solve the above-mentioned problems of polyolefins,
The present invention was completed based on this knowledge.

OH (However, in the formula, R1, R2, R3 and R4 each represent hydrogen or the same or different alkyl group having 1 to 8 carbon atoms.) As is clear from the above description, the purpose of the invention is to It is an object of the present invention to provide a polyolefin composition that is favorable for its mechanical processing stability, the thermal stability of molded products during practical use, and the effect of improving coloring properties caused by the antioxidant used. .

[Failure to solve the problem]

The present invention has the following configuration.

For 100 parts by weight of polyolefin, the following general formula (1
0.01 to 1 parts of a phenolic compound represented by 'l (hereinafter referred to as compound person) and a phosphite-based compound represented by the following general formula [:l]E (hereinafter referred to as compound B), respectively. A stabilized polyolefin composition comprising: 4 (However, in the formula, R1, R2, R3 and R4 each represent hydrogen or a quadruple or different alkyl group having carbons a1 to a8. Polyolefins used for Fufufu 1311 include ethylene, propylene, butene-1, and pentene. - Homopolymers of α-olefins such as 1,4-methyl-pentene-1,
Random copolymers or block copolymers consisting of two or more of these α-olefins, copolymers of these α-olefins with vinyl acetate, acrylic esters, etc. or saponified products thereof, or these α-olefins and unsaturated carboxylic acids Alternatively, a copolymer thereof with an anhydride or a reaction product of the copolymer and a gold maple ion compound can be exemplified.

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. In addition, the above polyolefins and various synthetic rubbers (e.g. ethylene propylene copolymer rubber, ethylene propylene non-conjugated diene copolymer rubber, polybutadiene, polyisoprene, chlorinated polyethylene/, chlorinated polypropylene, styrene butadiene rubber, styrene butadiene block) copolymer, styrene-in-prene block copolymer, styrene-ethylene-butadiene/block copolymer, etc.) or thermoplastic synthetic resins (e.g., polystyrene, sterenoacrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, polyamide, A mixture with polyethylene terephthalate, polybutylene terephthalate, polyvinyl chloride, etc.) can also be used.

Propylene monomers such as propylene homopolymer, ethylene propylene random copolymer, ethylene propylene block copolymer, ethylene globylene pute/-13 element copolymer, propylene hexene butene-13 element copolymer, and 2 of these. Mixtures of the above are particularly preferred.

An example of compound A used in the present invention is 1,3°5-trimethyl-2,4,6-)lis(3,5-di-t-butyl-4-hydroxybenzyl)benzene.

Compound 'i11! As I B, bisC2-t-butylphenyl)-pentaerythritol-siphosphite, bis(2-t-butyl-4-methylphenyl)-
Ventaerythritol diphosphite mata is bis(
Examples include 2,4-)-t-7'terphenyl)-pentaerythritol-shiphosphite. Particularly preferred is bis(24-di-t-butylphenyl)-pentaerythritol-shiphosphite. These compounds ql
The blending ratio of A and compound B is 100% polyolefin.
Each part by weight is 0.01 to 1N, preferably 0.01 to 0.5 part by weight. If the amount is less than 0.01 part by weight, the desired effect will not be fully exhibited, and although it is possible to add more than 1 part by weight, no further improvement in the effect can be expected and it is impractical and not foolish. It's uneconomical.

The composition of the present invention contains various additives that are normally added to polyolefins, such as phenolic, thioether, and phosphorus antioxidants, light stabilizers, clarifying agents, nucleating agents, lubricants, and charging agents. Inhibitor, health protection agent, anti-blocking agent, no-drop agent, #family, heavy metal deactivator (copper damage inhibitor),
Flame retardants, flame retardant aids, radical generators such as peroxides, dispersants or neutralizers such as metal soaps, and inorganic fillers (such as talc, mica, clay, wollastonite,
Zeolite, asbestos, calcium carbonate, aluminum hydroxide, magnesium hydroxide, (ii! barium acid,
Calcium silicate, glass fiber, carbon fiber, etc.) and organic fillers (for example, wood flour, pulp, waste paper, etc.) can be used in combination without impairing the purpose of the present invention.

The composition of the present invention is prepared by adding a predetermined amount of the above-mentioned compound VJB and each of the above-mentioned additives to the polyolefin using a conventional mixing device such as a Hensel mixer (trade name), a Suhami*t+, Mix using a ribbon blender, Pan Bali mixer, etc.
It can be obtained by melt-kneading and pelletizing using an ordinary single-screw extruder, twin-screw extruder, plastic pender, roll, etc. at a melt mixing temperature of 150°C to 300°C, preferably 180°C to 250°C. 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-kneading in the molding process stage, and there is no coloration caused by the antioxidant used, and molded products manufactured using the composition can be used in practical use. Because of its excellent thermal stability, it can be advantageously used in products in various molding fields. In addition, the composition of the present invention is particularly advantageous when used as a recycled product because it has excellent resistance to thermal oxidation deterioration during melt mixing, that is, thermal processing stability when subjected to thermal history due to several times of melt kneading. can do.

[For production]

In the present invention, the mechanism of action of the combined use of compound 'mA and compound vllJB during melt-kneading of polyolefin is not clear.

However, it is generally known that the phenolic oxidizing agent represented by Compound A acts as a radical chain inhibitor, and the phosphorus antioxidant represented by Compound *JB acts as a peroxide decomposer. However, compound people and combination *B
It has been found that by using these in combination, a surprising synergistic effect that could not be expected from the combination of a conventionally known 7-enol antioxidant and a phosphorus antioxidant is exhibited.

Furthermore, the reason why the composition of the present invention has excellent thermal stability during practical use is considered to be that the compound B used has a remarkable ability to regenerate the oxidized compound A.

[comes into effect]

The composition of the present invention has (1) resistance to thermal oxidative deterioration and coloration resistance during molding, compared to polyolefin compositions that use known phenolic antioxidants and phosphorus antioxidants alone or in combination; significantly superior to In particular, it is extremely excellent in thermal oxidative deterioration resistance during bath melt kneading, that is, thermal stress stability and coloration prevention property when subjected to thermal history due to several melt cross-wires during temperature measurement.

(2) When formed into a molded article, the molded article has excellent thermal stability during practical use.

〔Example〕

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

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

Measurement of melt flow rate (MFR) of obtained pellets (thermal processing stability)
(according to JISK6758) and Y of the obtained pellet
I (Yellowness Index) was measured (according to JISK7103), and this was determined as the IMPR.

This will be the 1st YI. Subsequently, using the obtained pellet, melt mixing was repeated twice at a bath melt kneading temperature of 270° C., and the MFR and Yl of the pellet thus obtained were measured each time.
Record as 3rd YI.

Evaluation was made based on the values of the second MFRX, third MFR, second YI, and third YI, and the values of MFR = 3rd MFR - 1st MFR ΔY) = 3rd YI - 1st YI.

The smaller these values are, the better the thermal oxidative deterioration resistance during melt-kneading, that is, the thermal processing stability.

(B1 coloring prevention property: Evaluated from the above-mentioned 1st YI and ΔYI.

(C) Thermal stability in practical use: Based on oven life test)
evaluated. That is, using the obtained pellet, the length is 50
A test piece with a width of 25B1 and a thickness of IR was prepared by injection molding, and the test piece was placed in a circulating hot air oven adjusted to a temperature of 150°C. time) measurement (JIS K7212
(Based on the following).

Example 1, Comparative Example 1-1'7, Reference Example 1 As polyolefin, MFR (discharge i of molten resin for 10 minutes when 9 is added to load 2.16 at 230°C) 6. O
r/l 0 min. 4-hydroxybenzyl)benzene, as compound @B, bis(2,4-sheet t-butylphenyl)-pentaerythritol-shiphosphite, respective predetermined amounts of other additives and 0.1 parts by weight of calcium stearate. The mixture was placed in a Hensel mixer (trade name) and stirred and mixed for 3 minutes, then melt-kneaded and pelletized at 200° C. in a 4-ON diameter single-screw extruder. Moreover, as Comparative Example 1-17 and Reference Example 1, powdered propylene monomer with MFR of 6 and Or/10 minutes! ! Predetermined amounts of each of the additives listed in Table 1 were blended with 1 part of 1○○ weight of Polymer No. 11 to obtain pellets in accordance with Example 1.

A test piece for evaluating thermal stability in practical use was obtained by molding the obtained pellet by injection molding at a resin temperature of 250'C.

Using the obtained pellets and test pieces, thermal processing stability, anti-coloring properties, and thermal stability in practical use were evaluated using the test methods described above.

These results are shown in Table 1.

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

Compound A (daytime molecular weight phenolic antioxidant B1.3.
5-) Remeter-2,4,6-)
Lis (3,5-di-t-butyl-4-hydroxybenzyl)benzene Low molecular weight phenolic antioxidant 1; 2,6-di-t-butyl-p-cresol High molecular weight phenolic antioxidant 1 Nidris (3,5-
di-t-butyl-4-hydroquinbenzyl) iso7anurate High molecular weight phenolic antioxidant 2; Tetrakis [methylene-3-(3',5'-di-t-butyl-4'-hydroquinphenyl) propionate) methane compound B; bis(2,4-di-t-butylphenyl)-
Pentaerythritol-shiphosphite phosphorus antioxidant 1; tris(2,4-di-t-butylphenyl)7 osphite phosphorus antioxidant 2; tetrakis(2,4-di-t-butylphenyl) -4, 4'-biphenylene diphosphonite As shown in Table 1, Example 1 uses the compound according to the present invention and Compound B. Comparing Example 1 with Comparative Examples 1 to 4, As a result, it can be seen that Example 1 has excellent thermal processing stability and anti-coloring properties.

In particular, ΔMFR was 0.2 in Example 1, indicating that there was almost no decrease in thermal processing stability even after three thermal cycles. Among Comparative Examples 1 to 4, the ΔMFR of Comparative Example 1 using BIT (low molecular weight phenolic antioxidant 1), which is the most commonly used, was 1.5, indicating that the composition of the present invention is significantly superior. It can be seen that the material has excellent thermal processing stability. Furthermore, when comparing Comparative Examples 5 to 7 (combined combination system of compound A and low molecular weight phenolic antioxidant or combination system of high molecular weight phenolic antioxidant and low molecular weight phenolic antioxidant) and Example 1, Comparative example 5
-7 all have large values of ΔMFR, and as is clear from the value of ΔYI, it can be seen that the anti-coloring property is extremely poor.

Comparative Examples 8 to 1O are examples in which only Compound B or a phosphorus antioxidant was used alone, and although they are superior to Example 1 in terms of color prevention, the difference is so small that it does not pose a practical problem. It's not the difference. However, in Comparative Examples 8 to 10, Δ
It can be seen that the value of MFR is larger than that of Example 1, and the thermal processing stability is inferior. However, in Example 1, compound A
It can be seen that a remarkable synergistic effect is obtained by combining Compound B with Compound B.

Comparative Examples 11 to 17 are examples of combination systems using combinations of high molecular weight phenolic antioxidants and phosphorus antioxidants other than the combination of Compound A and Compound 'JB. All have poor thermal processing stability.

Reference Example 1 is a combination of Compound B and a high molecular weight phenolic antioxidant disclosed in Japanese Patent Publication No. 59-21343, but Example 1 is a combination system using Compound A.
It can be seen that the thermal processing stability and coloring prevention properties are better.

Furthermore, it can be seen that Example 1 is also superior in terms of thermal stability (oven life) during practical use.

These results show that the composition of the present invention is superior in all respects to compositions containing conventionally known additives alone or in combination.The remarkable effects of the composition of the present invention are confirmed. Ta.

that's all

Claims (3)

[Claims] (1) A phenol compound represented by the following general formula [I] (hereinafter referred to as compound A) and a phosphite compound represented by the following general formula [II] (hereinafter referred to as compound B) are added to 100 parts by weight of the polyolefin. A stabilized polyolefin composition containing 0.01 to 1 part by weight of each of the following. ▲There are mathematical formulas, chemical formulas, tables, etc.▼[I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[II] (However, in the formula, R_1, R_2, R_3, and R_4 are each hydrogen, the same type of carbon number 1 to 8, or (Indicates different alkyl groups.) (2) Claim No. 1 in which the alkyl groups represented by R_1, R_2, R_3 and R_4 are t-butyl groups.
) The stabilized polyolefin composition according to item 1. (3) As compound A, 1,3,5-trimethyl-2,
4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene as compound B, bis(2,
Claim No. (4-di-t-butylphenyl)-pentaerythritol-diphosphite is blended.
The stabilized polyolefin composition according to item 1).