JPS6054344B2 - Polyolefin resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stabilized polyolefin resin, and uses dipentaerythritol diphosphite to prevent coloring of the polyolefin resin and to improve light resistance and heat resistance.

It is well known that polyolefin resins are susceptible to deterioration by heat and light due to their chemical structure, and in order to prevent this deterioration, various types of antioxidants, ultraviolet absorbers, and light stabilizers are added and used. There is. Polyolefin resins, especially polyethylene resins, polypropyne resins, etc., are very often used in white products or brightly colored products, and additives that do not color the resin are preferred. Non-polluting phenolic antioxidants and thioether antioxidants are often used as non-oxidant antioxidants. However, even with resins using phenolic antioxidants or thioether antioxidants, discoloration and deterioration of the resin often occur due to severe conditions such as advanced heat history and outdoor exposure, which can cause problems. In addition, UV absorbers and light stabilizers are generally added to resins intended for products that will be used outdoors over a long period of time, but commonly used benzotriazole-based UV absorbers do not color the resin. It is easy to limit the amount of use. Phosphorous compounds such as tris(nonylphenyl) phosphite and cyclic neopentanetetrayl bis(octadecyl phosphite) are added as antioxidants to prevent coloration of resins, but they do not prevent coloration or light resistance. It cannot be said that the improvements in properties and heat resistance are fully satisfactory. The present inventors used phenolic antioxidants, thioether antioxidants, ultraviolet absorbers, light stabilizers, etc. in polyolefin resins, each alone or in combination, to prevent coloring of the resins, improve light resistance, As a result of extensive research into the composition of antioxidants that can further improve heat resistance, we have found that the use of dipentaerythol diphosphite in combination with the antioxidants, ultraviolet absorbers, or light stabilizers significantly improves the coloring property. The present invention was completed by discovering that a polyolefin resin composition with improved light resistance and heat resistance can be obtained.

That is, the present invention provides for the use of any one of a phenolic antioxidant, a thioether antioxidant, an ultraviolet absorber, and a stabilizer.
and dipentaerythritol diphosphite.

This invention relates to a polyolefin resin composition with improved color resistance, light resistance, and heat resistance. In the present invention, the amount of dipentaerythritol diphosphite added to the polyolefin resin varies depending on the type of resin or the type of antioxidant, ultraviolet absorber, light stabilizer, etc. used in combination, but is generally 0.0
01-0.5% by weight is sufficient, preferably 0.00%
It is 5 to 0.5% by weight.

The polyolefin resin referred to in the present invention refers to polyethylene,
A synthetic resin whose main monomer is an olefin such as polypropylene, including polybutene-1, poly3 (methylbutene-1), poly(4-methylpentene-1), polystyrene, and combinations of polyethylene, polypropylene, and other compatible polymers. Also included are blends, such as blends of polyethylene, polypropylene with copolymers of ethylene, butene and other copolymerizable monopolymers. In addition, examples of phenolic antioxidants used in combination in the present invention include 2,6-di-tert-butyl-4-methylphenol, 2,2''-methylenebis(4-methyl-6-tert-butylphenol), tris (2-Methyl-4-hydroxy-5-tert-butylphenyl)butane, N-octadecyl-3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, Te.trakis[methylene-3(3,5- Examples of thioether antioxidants include, but are not limited to, di-tert-butyl-4-hydroxyphenyl) propionate] methane, etc. Examples of thioether antioxidants include dilauryl thiodipropionate, dimyristyl thio, etc. Examples include, but are not limited to, dipropionate, disterialylthiopropionate, pentaerythritol tetrakis (β-laurylthiopropionate), and the like.
Furthermore, as ultraviolet absorbers and light stabilizers, for example,
2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di tertiary butylphenyl)-5-chlorobenzotriazole, 4-
Examples include, but are not limited to, benzyloxy 2,2,6,6-tetramethylpiperidine, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, and the like.

The amount of the phenolic antioxidant, thioether antioxidant, ultraviolet absorber, and light stabilizer added to the polyolefin resin depends on the type of resin and the type of antioxidant, ultraviolet absorber, light stabilizer, etc. Although it varies depending on the case, the amount usually added to the polyolefin resin is sufficient, and preferably 0.01 to 1% by weight. The method for producing the polyolefin resin composition of the present invention is not particularly limited, but the additives and the polyolefin may be mixed using a method suitable for producing a uniform composition, such as a roll, Panbury mixer, calendar, kneader, etc. A method of mixing can be applied.

Furthermore, the composition of the present invention may contain additives such as lubricants, heavy metal deactivators, fillers, flame retardants, pigments, and antistatic agents, if necessary.

Note that dipentaerythritol diphosphite can be synthesized by, for example, transesterifying triphenylphosphite and dipentaerythritol using sodium hydride as a catalyst, distilling off the phenol under reduced pressure, and removing the residue from the pot. By recrystallizing the product in a solvent such as xylene, a pure white crystal with a melting point of 180°C can be obtained. This was confirmed to be dipentaerythritol diphosphite through elemental analysis, nuclear magnetic resonance spectrum, mass spectrometry, infrared absorption spectrum, and other analyses. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, and the stabilizing effect of the polyolefin resin according to the present invention will be explained in detail with reference to Experimental Examples. Example 1, Experimental Example 1 Additives were added to polypropylene resin (additive powder additive) in the proportions listed in Tables 1 to 5, and mixed thoroughly to produce 260
And C30T! r! ! The pellets were made into pellets using a tφ extruder and injection molded at 200°C to a thickness of 0.5Wrfn1 and a size of 40×8? A test piece was manufactured.

The degree of coloration (
Judging the degree of coloration of the pellets with the naked eye), light resistance (the time it takes to put the pellets in a fade tester until cracks appear), and heat resistance (the time it takes to put them in a gear open controlled at 150°C until they become brittle). Examined. Table 1 shows the results obtained.
~5. In addition, the symbols in the table are the compounds shown below.

A: dipentaerythritol diphosphite B: cyclic neopentane tetrayl bis(octadecyl phosphite) C: tris(nonylphenyl) phosphite D: 2,6-di-tert-butyl-4-methylphenol E: 1, 1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane F: Tetrakis [
Methylene-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] Methane G: Dimyristylthiodipropionate H: Calcium stearate 1:2 (2-hydroxy-5-methylphenyl)benzotriazole J: 2 ,7methylenebis(4-methyl-6
(tertiary butylphenol) K: bis(2,2,6,6
-tetramethyl-4-piperidine) sebacate Example 2
, Experimental Example The compounds shown in Table 6 were added to low-density polyethylene resin (no additives added), thoroughly mixed, and pelletized using a 230°C 3mm diameter extruder. Use a No. 3 dumbbell as a test piece by punching out the sheet.

The coloring degree of the extruded pellets and the data obtained by measuring the elongation before and after subjecting the test piece to ultraviolet radiation treatment for 2 (4) hours using a fade tester (carbon arc) are shown below. (The symbols shown in the table indicate the same compounds as in Example 1.) As can be seen from Experimental Examples 1 and 2 above, the addition of dipentaerythritol diphosphite significantly improved the colorability, and further improved the light resistance and Heat resistance is also improved.

Claims (1)

[Claims] 1 Color resistance, light resistance, and heat resistance characterized by containing one or more of phenolic antioxidants, thioether antioxidants, ultraviolet absorbers, and light stabilizers and dipentaerythritol diphosphite. A polyolefin resin composition with improved properties.