JPS5932491B2 - Polyolefin resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stable polyolefin resin composition that is resistant to heat, light, oxidation, and the like.

Because of their excellent physicochemical properties, olefin polymers are used in many fields in the form of molded products, films, fibers, etc. by various molding or spinning methods.
As is well known, the molding process of olefin polymers is usually performed at high temperatures, and when the polymer is processed or used, it changes over time due to heat and light, resulting in oxidative deterioration and mechanical properties due to a decrease in molecular weight. There are drawbacks such as a decrease in color, coloration, and odor.

Therefore, conventionally, olefin polymers have almost never been used alone, and are usually combined with deterioration inhibitors such as various antioxidants and ultraviolet absorbers to provide resistance to heat and light. It is included as

However, although phenol-based, sulfur-containing, amine-based, and phosphite-based antioxidants are typically known as antioxidants, they are considered to be effective in stabilizing olefin polymers, compatibility, non-staining properties, etc. In view of this, it is not completely satisfactory in practical terms. In other words, these antioxidants have poor compatibility with the olefin polymer, so they tend to bleed onto the surface of the molded product and contaminate the product.In addition, many of these antioxidants have low boiling points and evaporate during processing by heating the resin. However, there are drawbacks such as not only the effect of the additive cannot be fully demonstrated, but also the working environment is deteriorated due to the generation of foul odors.

Moreover, since these additives Ii are also expensive, improvements have been desired so that they can fully achieve their original purpose. In view of the above facts, the present inventors conducted intensive research to improve the
It has been found that when hydroxyapatite is used in combination with a deterioration inhibitor, a remarkable synergistic effect is exhibited.

Incidentally, it is known to add this hydroxyapatite to polyolefin resins.

(JP-A-47-9032, JP-A-47-9033)
This is not limited to olefin resins, but also includes adding a small amount of hydroxyapatite as a type of inert substance with a specific particle size to prevent adhesion at the interface between film layers of various thermoplastic films and improve the so-called rolling characteristics. This is something that has been proposed and is essentially different from the present invention. That is, the present invention relates to a polyolefin resin composition characterized in that the olefin polymer contains a deterioration inhibitor and hydroxyapatite.

In the present invention, hydroxyapatite is another name for tribasic calcium phosphate, and has the general formula CaO. 5m+
It is calcium orthophosphate which can be expressed as 1.5n(0H)m(PO4)n. The composition, particle size, shape, etc. of this compound vary significantly depending on its manufacturing conditions, but it can be applied without being limited by particle properties or composition as long as the particle size is about 20 μm or less. However, in most cases, uniform and fine particles with a molar ratio Ca/P of 1.5 to 1.8, preferably 1.6 to 1.7 and an average particle diameter of 3 μm or less are preferable. Such hydroxyapatite is synthesized by an alkaline precipitation reaction between a calcium salt, such as an aqueous calcium chloride solution, and a phosphoric acid, such as an aqueous sodium phosphate solution.

As mentioned above, its physicochemical properties vary depending on the reaction temperature, type of reactant, reaction ratio, ripening method, and other manufacturing conditions. In the present invention, the properties of fine basic calcium phosphate, ie, hydroxyapatite, are not particularly important, but other acidic salts such as dicalcium phosphate or monocalcium phosphate are not suitable.
The reason for this is that, like apatite, these salts have the ability to stabilize resins, but when added to resins and used, they have a major drawback in blooming, a phenomenon in which the composition is discharged from inside the resin and deposited on the resin surface. Because there is. The amount of hydroxyapatite added varies depending on the type of resin, but in general, the appropriate amount is 0.1 to 2 parts by weight per 100 parts by weight of resin. If the amount is too large, the transparency of the resin will be impaired and the effect of increasing the amount will be small.

On the other hand, in the present invention, the deterioration inhibitor to be used in combination with the hydroxyapatite is a resin for preventing deterioration of the olefin polymer caused by oxidation, heat, light, ozone, heavy metals such as copper and manganese, or mechanical fatigue. Typical examples of additives include antioxidants, but other additives include ultraviolet absorbers, ozone deterioration inhibitors, light stabilizers, etc., and these are not necessarily limited. Examples of antioxidants include 2,6-di-tert-butylphenol,
2,6-di-tert-butyl-4-ethylphenol, 2,
6-di-tert-butyl-4-methylphenol, 2,6-
Di-tert-butyl-4-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-α-dimethylamino-p-cresol, 6-(
4-Hydroxy-3,5-di-tert-butylanilino)-
2,4-bisoctyl-thio-1,3,5-to1 azine, n-octadecyl-3-(47-hydroxy-37
,5/-di-tert-butyl pheninopropionate, pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]
, 2,2-bis(4!-oxypheno(c)propane, 4,4L butylidenebis(3-methyl-6-tert-butylpheno(c), 4,4/-dihydroxydiphenyl, 2,2'-methylene- Bis-(4-methyl-6-tert-butylphenol), 2,2L methylene-bis-(4-methyl-6-tert-butylphenol),
-ethyl-6-tert-butylphenol), 4,4L methylene-bis-(2,6-di-tert-butylphenol),
Hindered bisphenono ν, tris-(2-methyl-4-hydroxy-5-tert-butylphenyl)butane,
4,4L thiobis-(6-tert-butyl-3-methylphenol), 4,47-thiobis-(6-tert-butyl-0
-cresol), phenolic antioxidants such as dialkyl phenol sulfide, dilauryl thiodipropionate, distearyl thiodipropionate, distearyl β-β7-thiodibutyrate, lauryl stearyl thiodipropionate nate, dimyristyl thiodipropionate, ditridecyl thiodipropionate, amyl thioglycol, l-1! -thiobis(2-
naphthol), 2-mercaptobenzimidazole, 2
- Sulfur-containing antioxidants such as mercaptomethyl benzimidazole, tri(nonylphenyl) phosphite,
Phosphite-based antioxidants such as Tris (mixed mono- and di-nonylphenylated phosphites and alkylated allyl phosphites), other amine-based antioxidants, and hydrazine derivative waxes are included.

Examples of ultraviolet absorbers include p-octylphenyl.
Salicylic acid derivatives such as salicylate, benzophenone derivatives such as 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 4-dodecyloxy-12-hydroxypenzophenone , 2-(2!-hydroxy-37-tert-butyl-51-methyl-phenyl)-5-chlorobenzotriazole, 2-(2!-hydroxy-37,5'-di-tert-butyl-phenyl)-5- Benzotriazole derivatives such as chlorobenzotriazole, 2-(2-hydroxy-4'-n-octoxyphenyl)benzotriazole, oxalic acid anilide derivatives, 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate, etc. can be given.

Examples of light stabilizers include hindered amine type compounds, benzoic acid derivatives, [2,2L thiobis-(4-tertiary octylphenolite)]-n-butylamine, nickel, and nickel chelate compounds. Incidentally, those listed above are typical deterioration inhibitors, and the present invention is not limited to these, and almost any additive for preventing deterioration of olefin polymers can be practically applied. Examples of the polyolefin resin that can be stabilized in the present invention include polyethylene, polypropylene, α-olefin polymers such as polybutene-11 poly-3-methylbutene, ethylene monovinyl acetate copolymer, ethylene-propylene copolymer, ethylene -α of ethyl acrylate copolymer, etc.
- Copolymers of olefins and other monomers, blends of polyolefins and other synthetic resins, block copolymers and graft copolymers, and even polyolefin resins exposed to peroxides or radiation. Also included are crosslinked polyolefins that are crosslinked and foamed polyolefins that are foamed using a blowing agent.

As described above, the present invention provides a polyolefin resin composition containing an anti-deterioration agent, by incorporating the above-mentioned hydroxy abatite to promote the original function of the anti-deterioration agent and create an olefin resin composition with extremely excellent stability. A resin composition can be obtained.

Although the mechanism of action is not clear, hydroxyapatite adsorbs and retains deterioration inhibitors, or captures metal catalysts remaining in the resin, thereby improving the properties of olefin resins during hot molding and products. It is thought that it prevents the decomposition and volatilization of antioxidants and the like when the resin is used, and maintains its original efficacy.

It also has the function of preventing the antioxidant from blooming or bleeding onto the resin surface, which is also thought to be based on the reasons mentioned above. The ratio of the deterioration inhibitor to hydroxyapatite varies depending on the conditions, but is preferably in the range of 10:1 to 1:500, preferably 1:1 to 1:100.

The method of blending the polyolefin resin composition according to the present invention is not limited as long as it can produce a uniform composition.

Furthermore, in the molding process of resin, the conventional force method can be applied as is. In addition, other resin compounding agents such as stabilizers, lubricants, dispersants, plasticizers, colorants such as pigments, fillers, etc. may be used in combination with the polyfine resin composition according to the present invention without any problem. can be done.

Thus, in the resin composition of the present invention, oxidative deterioration of the polyolefin resin due to heat or light is prevented, and in particular, discoloration or discoloration of the resin due to oxidative deterioration is significantly suppressed.

It also suppresses migration of deterioration inhibitors such as antioxidants or their decomposition products to the resin surface (freeding or blooming). In addition, significant synergistic effects such as anti-blocking effects can be expected. In particular, since the function of the anti-deterioration agent can be efficiently exhibited, it becomes possible to substantially reduce the amount of expensive anti-deterioration agent added, and the present invention has great industrial significance. The present invention will be specifically described below with reference to Examples.

The method for preparing calcium phosphate used in the Examples and Comparative Examples of the present invention is as follows.

(1) Hydroxyapatite Ca5(PO4)3(
0H) Phosphoric acid was gradually added to an aqueous slurry of calcium hydroxide at 90° C. under stirring to crystallize into hydroxyapatite in about 8 hours.

The crystallized hydroxyapatite was separated from the mother liquor, dried, and ground to provide a sample. (2)
Calcium dihydrogen phosphate (basic calcium phosphate)
After adding calcium carbonate to Ca(H2PO4)2.H2O6O wt% phosphoric acid at a molecular ratio of 2:1, an excess of phosphoric acid was further added and the mixture was heated and stirred to completely dissolve the calcium carbonate.

This solution was cooled, and the resulting crystals were filtered, dried, and ground to provide a sample. (3) Calcium hydrogen phosphate (dibasic calcium phosphate) An aqueous slurry of calcium hydroxide (15% by weight) was gradually added to a CaHPO4.2H20 phosphoric acid aqueous solution (15% by weight as H3PO4) under stirring, and reacted to pH 4. 5. The mixture was stirred for about 2 hours at a temperature of 40° C. or less for crystallization.

This was separated from the mother liquor, dried, crushed, and used as a sample. (1) Calcium pyrophosphate Ca2p2O7 calcium hydrogen phosphate (dibasic calcium phosphate) was calcined at 800° C. for 2 hours, then ground and used as a sample.

The evaluation method for the polyolefin resin compositions used in the Examples and Comparative Examples of the present invention is as follows.

(1) Static Thermal Stability A polyolefin resin composition having a predetermined formulation was kneaded using a test roll under predetermined conditions and molded into a sheet having a thickness of 11111 mm.

The obtained sheet is 3CfL×5? It was cut into test pieces. A gear with a test piece kept at 200℃. The polyolefin resin composition was placed in an oven and the change in heat coloring over time was observed, and the heat resistance stability of the polyolefin resin composition was evaluated using the following numerical values. (2) Blooming resistance 0.3 PHR of carbon black is added to a polyolefin resin composition with a predetermined composition and kneaded with test rolls under predetermined conditions. It was molded into a thick sheet.

Two of the obtained sheets were stacked and hot pressed at 200° C. and 150 kg/d. This press plate was immersed in hot water at 70° C. for 24 hours, air-dried, and the degree of discharge onto the surface (blooming) was observed with the naked eye and evaluated using the following three numerical values. Example 1 In order to investigate the effect of adding hydroxyapatite to ethylene monovinyl acetate copolymer, Evaflex 560# (manufactured by Mitsui Polychemical Co., Ltd., MI (melt index) 35, vinyl acetate content 14) was used as ethylene monovinyl acetate copolymer. %) in combination with PU-300PL (manufactured by Kosei Co., Ltd.), which is a stabilizer and lubricant for ethylene monovinyl acetate, was investigated.

The formulation is shown in Table 1, and the test roll conditions were 150℃, 5
It was molded by kneading for minutes. The results are shown in Table 1. Example 2 In order to investigate the effect of adding hydroxyapatite and calcium phosphate according to the present invention to ethylene monovinyl acetate copolymer resin, Ultrasen (630# (manufactured by Toyo Soda)
A test piece was prepared using the same rolling conditions as in Example 1 using the formulation shown in Table 2, and the thermal stability was examined.

We also examined blooming resistance. The results are shown in Table 2. Example 3 In Examples 1 and 2, we mainly showed the results of investigating the thermal stability and blooming resistance of PU-300PL in combination with hydroxyapatite, but here we will discuss the results of investigating the combination of PU-300PL and hydroxyapatite with other commercially available antioxidants. Table 3 shows the results of the study.

The compositions having the formulations shown in Table 3 were evaluated using the same force method as in Examples 1 and 2. The results are shown in Table 3. Example 4 The effect of the combined use of a commercially available antioxidant and hydroxyapatite on thermal stabilization of polyethylene was investigated.

The test was conducted using unstabilized high-density polyethylene resin powder (melt index 0.9) and various additives in the formulation shown in Table 4 at predetermined roll temperatures (front roll 16'C, rear roll 120C).
3 (1771
Example 5 The test piece was cut into 5 CTn pieces and the change in thermal coloring over time was investigated in a gear oven at 200°C.The effect of a combination of a commercially available antioxidant and hydroxyapatite on thermal stabilization of polypropylene was investigated.

The test was conducted by kneading unstabilized polypropylene resin (melt index 1.5) and various additives in the formulation shown in Table 5 for 5 minutes at a predetermined roll temperature (front roll 160 °C, rear roll 120 °C) and molding. The resulting sheet was cut into 3 cm x 5 cm pieces to make test beads, and changes in heat coloring over time were examined in a gear oven at 200°C.

Claims (1)

[Scope of Claims] 1. A polyolefin resin composition comprising an olefin polymer containing a deterioration inhibitor and hydroxyapatite. 2. The polyolefin resin composition according to claim 1, wherein the polyolefin resin is an ethylene-vinyl acetate copolymer, polyethylene, or polypropylene. 3. The polyolefin resin composition according to claim 1 or 2, wherein the amount of hydroxyapatite added is 0.1 to 2 parts by weight per 100 parts by weight of the polyolefin resin.