JPH0711072A - Polyethylene resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition excellent in impact resistance, appearance and stiffness and suitable for rotation molding method by including a linear low-density polyethylene, a flame retardant, a metal oxide and a light- resisting stabilizer at specific ratios. CONSTITUTION:This resin composition contains (A) 100 pts.wt. of a linear low- density polyethylene (preferably a copolymer of ethylene and 6-10C alpha-olefin) having 1-10g/10min melt index and 0.920-0.944g/cm<3> density, (B) 1-25 pts.wt. flame retardant, (C) 0.2-15 pts.wt. of at least one kind of metal oxide, preferably among antimony oxide, titanium oxide and zinc oxide and (D) 0.001-3 pts.wt. of a light-resisting stabilizer and/or 0.0001-3 pts.wt. of a carbon black. This composition is preferably a powdery composition having <=30 mesh size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene resin composition, and more specifically, it is suitable for various molding methods, particularly rotational molding, and has excellent balance in impact resistance, appearance and rigidity, and further in weather resistance and difficulty. The present invention relates to a polyethylene resin composition which gives a molded article excellent in flammability.

[0002]

2. Description of the Related Art The rotational molding method has a relatively low die cost as compared with other molding methods, and is suitable for the production of large molded articles and hollow articles having complicated shapes. Since it can be applied, it is widely used for producing a large number of small quantities of molded products.

However, the rotational molding method has a lower packing density as compared with injection molding, hollow molding, etc., so that the impact resistance of the molded product is
This molding method makes it difficult to balance rigidity and appearance (such as sink marks). As a way to balance these,
A polyethylene resin composition obtained by mixing linear low-density polyethylene and high-density polyethylene is disclosed in Japanese Patent Publication No. 4-77.
Although it is disclosed in No. 019, since it is a combination of those with greatly different melt indexes, granulation becomes unstable due to surging during kneading, and the appearance of sink marks etc. of molded products by adding high density polyethylene And deterioration of impact resistance.

As a result of diligent research conducted by the present inventors based on such circumstances, a flame retardant and a metal oxide, a light resistance stabilizer and / or carbon black are blended in a specific ratio in a specific linear low density polyethylene. By doing
Impact resistance, without deteriorating the appearance and impact resistance of the product.
The inventors have completed the present invention by finding that the balance between rigidity and appearance can be improved and that weather resistance and flame retardancy can also be improved.

That is, the object of the present invention is that it can be suitably used as an outdoor material which is excellent in moldability by various molding methods, particularly rotational moldability, and is also excellent in weather resistance and flame retardancy. It is to provide a polyethylene resin composition.

[0006]

According to a first aspect of the invention for solving the above-mentioned problems, (A) the melt index is from 1 to 10 g / 10 minutes and the density is from 0.920 to
100 parts by weight of linear low-density polyethylene having 0.944 g / cm ³ , 1 to 25 parts by weight of (B) flame retardant, 0.2 to 15 parts by weight of (C) metal oxide, and (D) light stabilizer. It is a polyethylene resin composition characterized by containing 0.001 to 3 parts by weight and / or 0.0001 to 3 parts by weight of carbon black. The invention according to claim 2, wherein the metal oxide is antimony oxide. The polyethylene resin composition according to claim 1, wherein the polyethylene resin composition is at least one selected from the group consisting of, titanium oxide, and zinc oxide, and the linear low-density polyethylene is ethylene and carbon. The polyethylene resin composition according to claim 1, which is a copolymer with an α-olefin having a number of 6 to 10, and the invention according to claim 4 is 30.
The polyethylene resin composition according to claim 1, which is in the form of powder below a mesh, and the invention according to claim 5 is:
The polyethylene resin composition according to claim 4, which is for rotational molding.

The present invention will be described in detail below.

-Linear low-density polyethylene-The linear low-density polyethylene in the present invention has a melt index (MI) of 1 to 10 g / 10 minutes, preferably 2 to 6 g / minute. MI is 1g / 10
If the amount exceeds 5 minutes, the appearance of the molded product becomes poor, for example, the skin becomes discolored. If the MI exceeds 10 g / 10 minutes, the resin drips during cooling, which causes a problem that the thickness of the product becomes uneven.

The melt index of the linear low-density polyethylene referred to herein is in accordance with JIS K7112 and is 1
It can be measured by annealing at 20 ° C. for 1 hour. Density is in accordance with JIS K7210, 190 ℃,
It can be measured with a load of 2.16 kg.

The linear low density polyethylene of the present invention has a density of 0.920 to 0.944 g / cm ³ ,
It is preferably 0.925 to 0.940 g / cm ³ .
When the density is less than 0.920 g / cm ³ , the rigidity of the molded product becomes insufficient and it cannot be used as an industrial material, and when it exceeds 0.944 g / cm ³ , the impact resistance decreases and the product becomes Poor appearance such as sink marks.

The linear low-density polyethylene in the present invention is preferably a copolymer of ethylene and an α-olefin having 6 to 10 carbon atoms, particularly 8 carbon atoms.

When the comonomer has less than 6 carbon atoms, the impact resistance of the molded article is lowered and the environmental stress crack resistance (ESCR resistance)
Sex) is also reduced. On the other hand, when the carbon number exceeds 10, the rigidity and flame retardancy decrease.

The copolymerization amount of the comonomer in the linear low density polyethylene is preferably 3 to 20% by weight. Within this range, it is easy to bring the density of the linear low-density polyethylene within a predetermined range, although there is a slight difference depending on the manufacturing method.

-Flame Retardant- The flame retardant in the present invention is not particularly limited, and various flame retardants can be used.

Among them, one of the preferable flame retardants is a flame retardant having a melting point or softening point of 230 ° C. or lower, particularly 40 to 220 ° C.

As the flame retardant having a melting point or softening point of 230 ° C. or lower, brominated bisphenol A type epoxy polymer, tetrabromobisphenol A, bistribromophenoxyethane, hexabromocyclododecane, bromine-containing aliphatic phosphate ester, Examples thereof include tetrabromobisphenol A carbonate oligomer, brominated styrene, polydibromophenylene oxide, chlorinated paraffin, and triphenyl phosphate. These may be used alone or in combination of two or more. Among these, preferred flame retardants are brominated bisphenol A type epoxy polymers and the like.

Besides the above flame retardants, one preferable flame retardant is a flame retardant having an average particle size of 10 μm or less, particularly 0.1 to 5 μm. Examples of such flame retardants include aliphatic addition type flame retardants, alicyclic addition type flame retardants, and biphenyl addition type flame retardants.

Examples of the flame retardant having an average particle size of 10 μm or less include decabromodiphenyl ether, ethylenebistetrabromobutalimide, perchlorocyclopentadecane, magnesium hydroxide and the like. The above-mentioned various flame retardants may be appropriately selected and used alone or in combination of two or more. Among these, preferred flame retardants are decabrodiphenyl ether and the like.

In this case, the melting point or softening point is 230 ° C.
Any flame retardant having a mean particle size of 10 μm or less can be preferably used even if the flame retardant exceeds 10 μm. Further, any flame retardant can be preferably used as long as the melting point or softening point is 230 ° C. or lower even if the average particle diameter exceeds 10 μm.

In the present invention, the amount of the flame retardant compounded is 1 part with respect to 100 parts by weight of the linear low-density polyethylene.
-25 parts by weight is preferable, and 3-17 parts by weight is particularly preferable. If the content of the flame retardant is less than 1 part by weight, the rigidity and flame retardancy are not improved, and if it exceeds 25 parts by weight, the appearance and impact resistance are deteriorated.

-Metal Oxide- Examples of the metal oxide in the present invention include antimony oxide, titanium oxide, zinc oxide, molybdenum oxide, tin oxide and zirconium oxide. In the present invention, various metal oxides may be appropriately selected and used alone or in combination of two or more. Among various metal oxides, antimony oxide, titanium oxide and zinc oxide are preferable, and among them, antimony oxide, particularly antimony trioxide, titanium oxide and zinc oxide are particularly preferable.

In the present invention, the average particle size of the metal oxide used is preferably 0.01 to 8 μm, and particularly preferably 0.2 to 1 μm. When the average particle diameter of the metal oxide is within the above range, it is possible to suppress the decrease in impact resistance.

The amount of the metal oxide compounded is 0.2 to 15 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the linear low-density polyethylene. If the compounding amount of the metal oxide is less than 0.2 parts by weight, flame retardancy and weather resistance will be insufficient, and if it exceeds 15 parts by weight, low temperature impact resistance will be deteriorated.

The metal oxide is preferably added to the flame retardant in a weight ratio of 1/2 to 1/4. Within the ranges of these two compounding amounts, a molded article excellent in weather resistance and flame retardancy can be obtained.

-Light-proof stabilizer, carbon black-The light-proof stabilizer in the present invention is not particularly limited, but examples thereof include salicylic acid type ultraviolet absorbers such as phenyl salicylate and pt-butylphenyl salicylate,
Benzophenone-based UV absorbers such as 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-).
Examples thereof include t-butylphenyl) benzotriazole-based UV absorbers, cyanoacrylate-based UV absorbers, hindered amine-based light stabilizers, and nickel-based compounds. Among these, benzotriazole-based UV absorbers are preferable. In the present invention, one selected appropriately from various light stabilizers can be used alone, or two or more kinds can be used in combination.

The light resistance stabilizer preferably used in the present invention preferably has a melting point in the range of 40 to 220 ° C. As the light resistance stabilizer having a melting point within such a range, a commercially available light resistance stabilizer can be preferably used. Specific examples of the commercially available light stabilizer include Tinuvin P, Tinuvin 326, Tinuvin 327, Tinuvin 770 (trade name, manufactured by Ciba-Geigy), Sumisorp 110 (trade name, manufactured by Sumitomo Chemical Co., Ltd.), and the like.

The light stabilizer is blended in an amount of 0.001 to 3 parts by weight based on 100 parts by weight of linear low-density polyethylene.
It is preferably 0.01 to 1.5 parts by weight, particularly preferably 0.1 to 1.0 part by weight. If the amount of the light resistance stabilizer is less than 0.001 part by weight, the weather resistance is deteriorated, and if it exceeds 3 parts by weight, impact resistance and flame retardancy are deteriorated, and further, there is a problem of deterioration of surface appearance such as yellowing and bleeding. Occurs.

The carbon black in the present invention is not particularly limited and, for example, channel black, furnace black, thermal black, acetylene black and the like can be preferably used. Among them, furnace black is preferable because the rigidity and weather resistance are greatly improved by using it.

The particle size of carbon black is preferably 10 to 30 mμ, and particularly preferably 15 to 25 mμ. This is because the rigidity and weather resistance can be improved.

The blending amount of carbon black is 0.0001 to 3 with respect to 100 parts by weight of linear low-density polyethylene.
Parts by weight, preferably 0.001 to 2 parts by weight, particularly preferably 0.01 to 2 parts by weight. If it is less than 0.0001 part by weight, the weather resistance will decrease, and if it exceeds 3 parts by weight, moldability and impact resistance will decrease.

In the polyethylene resin composition of the present invention, only one of the light resistance stabilizer and carbon black may be used, or both may be used. When both are used together, the total blending amount is linear low-density polyethylene 10
0.001 to 5 parts by weight relative to 0 parts by weight, particularly 0.1 to 2
It is desirable to use parts by weight. When it is less than 0.001, the weather resistance is lowered, and when it exceeds 5 parts by weight, the moldability and flame retardancy are lowered.

-Other Optional Components- The polyethylene resin composition of the present invention comprises a linear low-density polyethylene having the specific melt index and density, the flame retardant, the metal oxide, and the light fastness stabilizer. It is important to contain the above-mentioned specific ratio and / or carbon black, but various other components may be contained within a range not impairing the object of the present invention.

Examples of such other components include a lubricant, an antioxidant, an antistatic agent, a release agent, a colorant, an inorganic filler, a reinforcing material and an ultraviolet absorber.

As the lubricant, for example, liquid paraffin,
Hydrocarbon lubricants such as natural paraffin and wax; fatty acid lubricants such as higher fatty acids such as stearic acid, palmitic acid, oleic acid, myristic acid, behenic acid and oxyfatty acids; stearic acid, palmitic acid, oleic acid, myristic acid, Fatty acid ester type which is a lower alkyl ester such as methyl, ethyl, propyl and butyl of higher fatty acid such as behenic acid; aliphatic higher or lower alcohol, alcohol type lubricant such as polyglycol;
Examples thereof include metal soaps such as calcium stearate and barium stearate; silicone oils and silicones such as modified silicone.

Examples of the antioxidant include 2,6
-Di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) ) Propionate, 2,2-
Methylenebis (4-methyl-6-t-butylphenoac), 2,2-methylene-bis- (4-ethyl-6-t
-Butylphenol), 4,4-thiobis (3-methyl-6-t-butylphenol), 4,4-butylidenebis- (3-methyl-6-t-butylphenol), tetrakis {methylene-3- (3,5- Di-t-butyl-4
-Hydroxyphenyl) propionate} methane, 1,
1,3-tris- (2-methyl-4-hydroxy-5-
phenol-based compounds such as t-butylphenyl) butane, amine-based compounds such as phenyl-β-naphthylamine, N, N-diphenyl-p-phenylenediamine,
Phosphorus compounds such as tris (nonylphenyl) phosphite, triphenylphosphite, trioctadecylphosphite, diphenylisodecylphosphite, dilaurylthiodipropionate, dimyristylthiodipropionate, distearylthiodipropionate Examples thereof include sulfur compounds.

Examples of the antistatic agent include nonionic antistatic agents such as polyoxyethylene alkylamines and polyoxyethylene alkylamides, anionic antistatic agents such as alkyl sulfonates and alkylbenzene sulfonates, and quaternary antistatic agents. Ammonium chloride,
Examples thereof include cationic antistatic agents such as quaternary ammonium sulfate, and amphoteric antistatic agents such as alkylbetaine type and alkylimidazoline type.

Examples of the releasing agent include carnauba wax, paraffin wax, silicone oil and the like.

As the colorant, an ordinary colorant used for coloring plastics can be used.

Examples of the inorganic filler include calcium carbonate, calcium sulfate, magnesium sulfate, barium sulfate, talc, mica, silica, asbestos, glass beads, glass flakes, titanium oxide, zinc oxide, magnesium oxide, molybdenum oxide, and oxidation. Examples thereof include tin, zirconium oxide, iron oxide, alumina, quartz powder, and metal powder.

Examples of the reinforcing agent include glass fiber, carbon fiber, metal fiber and metal whiskers.

As the ultraviolet absorbent, known ultraviolet absorbents other than the above light resistance stabilizer can be used.

In the present invention, in addition to the flame retardant specified in the present invention, other halogen-based, phosphorus-based or inorganic flame-retardant, and other thermoplastic resin, rubber, elastomer, etc. may be added as required. It can also be used.

The method for preparing the polyethylene resin composition of the present invention is not particularly limited, and includes, for example, the above-mentioned component (A), component (B), component (C) and component (D) and various types used as desired. It is prepared by melt-kneading the optional components using a ribbon blender, a tumble mixer, a Henschel mixer, an open roll, a Banbury mixer, a single screw extruder, a twin screw extruder, a single reciprocating screw extruder and the like. be able to.

The polyethylene resin composition of the present invention can be formed into sheets, films, pipes, etc. by known molding methods such as rotational molding method, inflation molding method, cast molding method, extrusion molding method, injection molding method and extrusion molding method. It can be molded into various types of molded bodies. However, among the various molding methods described above, the polyethylene resin composition of the present invention is well suited for rotational molding.

When the polyethylene resin composition of the present invention is used as a rotational molding resin composition, the polyethylene resin composition is preferably a powder having a particle size of 30 mesh or less. When a molded product is formed by a rotational molding method using the polyethylene resin composition of the present invention, which is a powder having a particle size of 30 mesh or less, the impact resistance, rigidity, and appearance are well-balanced, and the weather resistance is high. Further, it is possible to obtain a rotomolded article excellent in flame retardancy.
Therefore, the rotomolded product of this polyethylene resin composition can be suitably used as a material that can be installed outdoors and as a concrete substitute product.

[0046]

【Example】

(Examples 1 to 6, Comparative Examples 1 to 6) Each component shown in Table 1, and
0.05 parts by weight of antioxidant (Irganox 1010 manufactured by Ciba-Geigy) based on 100 parts by weight of polyethylene
And were dry-blended, and kneaded with a biaxial kneader under the conditions of a heating temperature of 200 ° C. and a rotor speed of 700 rpm to obtain pellets.

The components in Table 1 are shown below.

Polyethylene A1; Kind: Linear low-density polyethylene (manufactured by Idemitsu Petrochemical Co., Ltd., Moretec 0368R) Melt index (MI): 3 g / 10 minutes Density: 0.935 g / cm ³ Comonomer carbon number: 8 A2; Type: linear low-density polyethylene (manufactured by Idemitsu Petrochemical Co., Ltd., Idemitsu Polyethylene-L0464R) MI: 4 g / 10 min Density: 0.935 g / cm ³ Carbon number of comonomer: 4 A3; Type: linear Low density polyethylene (manufactured by Idemitsu Petrochemical Co., Ltd., Moretec 0438CN) MI: 4 g / 10 min Density: 0.916 g / cm ³ carbon number of comonomer: 8 A4; type: linear low density polyethylene MI: 0. 8 g / 10 min Density: 0.935 g / cm ³ Carbon number of comonomer: 8 A5; Type: High density polyethylene (Idemitsu Petrochemical Co., Ltd. )
Manufactured by Idemitsu Polyethylene 230J) MI: 5.5 g / 10 min Density: 0.961 g / cm ³ Flame retardant B1; Type: Decabromodiphenyl oxide (manac, EB-10WS) Melting point: 304 ° C, average particle size: 3-5 μm, molecular weight 9
59 B2; type: brominated bisphenol A type epoxy polymer (Plaserm EC-20, manufactured by Dainippon Ink and Chemicals, Inc.) melting point: 115 ° C., molecular weight 2000 metal oxide C1; type: antimony trioxide (Nippon Seisei) Mining Co., AT
OX-S) Average particle size: 0.5 μm C2; Type: Titanium oxide (manufactured by Thai Oxide Group, R-TC30) Average particle size: 0.2 μm Carbon black and light stabilizer Carbon black: Cabot, Vulcan 9A -3
2 Particle diameter: 19 mμ Light resistance stabilizer: Benzotriazole-based ultraviolet absorber (Tinubin 326, manufactured by Nippon Ciba-Geigy Co., Ltd.) <Evaluation test> (1) Evaluation test by test piece Various pellets obtained by the above-mentioned method are prescribed. Molding was carried out by the molding method, and the obtained test pieces were evaluated.

(A) Flame retardancy (horizontal test) By injection molding, a UL94 standard test piece (thickness 1/8)
Inch). Hold the obtained test piece horizontally, 1
After touching an inch methane gas blue flame for 30 seconds,
The flame was removed from the test piece and the afterflame time (second) was measured.

(B) Rigidity The tensile modulus was measured according to JIS K-7113. However, the test piece is molded by injection molding, and JIS2
No. dumbbell and 1% secant.

(C) Izod impact strength For test pieces obtained by injection molding, JIS K-
It measured based on 7110 (with a notch). The test temperature was 23 ° C. The evaluation result of the Izod impact strength by this test piece is shown as A in Table 1.

(2) Evaluation test using actual molded products Various pellets obtained by the above-mentioned method were mechanically crushed,
Each powder was 30 mesh or less. Using this powder, the furnace temperature is 270 ° C., the heating time is 15 minutes, and the cooling time is 15 minutes.
A storage box as shown in FIG. 1 was produced by rotational molding under the condition of minutes.

As shown in FIG. 1, this storage box is
It comprises an upper lid 1 and a body 2, and a snap fit 3 is formed on the body 2. When the body 2 is covered with the lid 1, that is, when the upper lid 1 is pushed into the body 2 in the direction of the arrow Y in the figure, a key-like portion 4 is formed on the upper lid 1 at a position where the body 2 is engaged with the snap fit 3. ing. Due to the snap fit 3 and the key-shaped portion being caught, the pushed upper lid 1 cannot be easily removed from the body 2.

(A) Izod impact strength A snap fit portion of this storage box was cut out, and a test piece for measuring Izod impact strength (with a notch,
A wall thickness of 5 mm was obtained. The measurement was performed according to JIS K7110. The measurement result of the Izod impact strength of this actual molded product is shown by B in Table 1. This storage box is used as an industrial material outdoors.

The measured value of this Izod impact strength is 3 k.
When it is g · cm / cm or less, it is insufficient as an industrial material such as cracking when the lid of the storage box is opened with a burl or the like.

(B) Appearance The surface condition of the storage box and the sink marks on the upper and side surfaces were visually observed and judged. As a result of the judgment, those with no sink mark and good surface condition are ○, those with sink mark or defective dispersion are △, the sink mark is large, and the deformation on the side of the storage box is large. , Those with large surface roughness such as poor fusion and yuzu skin were represented by x.

[0057]

[Table 1]

[0058]

According to the present invention, the appearance and durability of the product can be improved by blending a specific linear low-density polyethylene with a flame retardant, a metal oxide, and further a light resistance stabilizer and / or carbon black in a specific ratio. It is possible to improve the balance of impact resistance, rigidity and appearance of a molded product, particularly a molded product obtained by rotational molding, and also improve weather resistance and flame retardancy without lowering the impact resistance.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an actual molded product used to evaluate the effects of the present invention.

[Invention of code]

1 ... Top lid, 2 ... Body, 3 ... Snap fit, 4 ... Key part

[Figure 1]

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[Procedure amendment]

[Submission date] July 6, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C08L 101: 04)

Claims (5)

[Claims] 1. (A) The melt index is 1 to 10 g.
/ 10 minutes and the density is 0.920 to 0.944 g / c.
linear low density polyethylene 100 parts by weight is m ^3,
(B) Flame retardant 1 to 25 parts by weight, (C) Metal oxide 0.2
˜15 parts by weight, and (D) light stabilizer 0.001 to 3
Parts by weight and / or carbon black 0.0001 to
A polyethylene resin composition comprising 3 parts by weight. 2. The polyethylene resin composition according to claim 1, wherein the metal oxide is at least one selected from the group consisting of antimony oxide, titanium oxide and zinc oxide. 3. The polyethylene resin composition according to claim 1, wherein the linear low-density polyethylene is a copolymer of ethylene and an α-olefin having 6 to 10 carbon atoms. 4. The polyethylene resin composition according to claim 1, which has a powder form of 30 mesh or less. 5. The polyethylene resin composition according to claim 4, which is for rotational molding.