JP2000143888A - Polyolefinic resin composition and resin material for blow molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyolefinic resin composition which neither needs the use of a corrosion-protected apparatus nor suffers from gel formation, has high melt tension, and is excellent in processibility, applicable to blow molding, expansion molding, sheet forming or the like and capable of giving a molded product exhibiting excellently balanced rigidity, heat resistance and impact resistance. SOLUTION: The title composition comprises components (A), (B) and (C) and has a ratio (σ), of the maximum stress value (σmax) to the stress value (σ1) at a strain of 1.0 in stretching deformation, of at least 2.9. This composition comprises 99-1 wt.% of (A) a polyolefinic polymer, 1-99 wt.% of (B) a polyolefinic polymer modified with an unsaturated carboxylic acid or a derivative thereof and 0.01-2.0 pts.wt., based on 100 pts.wt. of the total of the components (A) and (B), of (C) a hydrotalcite compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin composition suitable for foam molding, sheet molding, especially blow molding.

[0002]

BACKGROUND OF THE INVENTION In blow molding, when a parison is extruded from a die, the parison is stretched longitudinally by its own weight. This phenomenon is called drawdown and causes uneven thickness of the molded product. This drawdown property is related to the melt tension (MT), and a parison having a small drawdown can be obtained from a polymer having a high melt tension.
Therefore, it is possible to obtain a molded product with less uneven thickness. Also,
In foam molding, in order to form closed cells in which gas is confined inside the molten resin, a polymer that also has a high melt tension is required. Therefore, the melt tension is used as a measure of workability in forming a polyolefin or the like. In the sheet forming, when preheating is performed when performing vacuum forming or pressure forming, the viscosity at the time of melting is required to the extent that the sheet does not sag.

[0003] As one of means for improving the melt tension of a polyolefin polymer, it is known to introduce ionic cross-linking. In this means, for example, to ethylene,
First, a polyolefin resin having a carboxyl group introduced into the polymer is produced by copolymerizing an unsaturated carboxylic acid or by grafting an unsaturated carboxylic acid to polyethylene, polypropylene, an ethylene-propylene copolymer, or the like. To this end, an ionic cross-linking is formed between carboxyl groups by a metal ion cross-linking agent such as zinc acetate, magnesium acetate and sodium hydroxide (see Japanese Patent Publication No. 39-6810, Japanese Patent Publication No. JP-A-43-27422, JP-A-61-12
3642, JP-A-61-252204).

[0004]

However, this technique has a drawback in that a metal ion crosslinking agent such as zinc acetate or magnesium acetate has a corrosive property, and therefore requires a device provided with anticorrosion treatment. Further, the metal ion crosslinking agent has poor dispersibility in polyolefin, and spots appear on the surface of the molded product, resulting in poor appearance. For the purpose of remedying these drawbacks, attempts have been made to blend a metal salt of a fatty acid and further a metal hydroxide and / or oxide with a polyolefin resin having an unsaturated carboxylic acid grafted thereto (JP-A-5-2535).
No. 6). However, this has the disadvantage that poor dispersion is likely to occur and a gel is likely to be generated in the polymer. Further, it is said that it is desirable to use a block copolymer, particularly, as a resin material for blow molding, which requires rigidity and impact resistance. However, a polyolefin-based block copolymer modified with an unsaturated carboxylic acid is particularly liable to gel and has a reduced molecular weight, so that rigidity and impact resistance may be impaired. The present invention has been made in order to solve the above problems, there is no need to use a device subjected to anticorrosion treatment or the disadvantage of gel generation, high melt tension, excellent workability, blow molding, foam molding, An object of the present invention is to provide a polyolefin-based resin composition which can be applied to sheet molding and the like, and can obtain a molded article having an excellent balance of rigidity, heat resistance and impact resistance.

[0005]

The polyolefin resin composition of the present invention has the following components (A), (B) and (C), and has a stress value at a strain of 1.0 during elongation deformation. the ratio of the maximum stress value (sigma _max) for (σ ₁₎ (σ) is characterized in that at 2.9 or greater. (A) The polyolefin polymer is 99 to 1 wt%. (B) The polyolefin polymer modified with an unsaturated carboxylic acid or a derivative thereof is 1 to 99 wt%. (C) The hydrotalcite compound is composed of the component (A) and (A). B) 0.01 to 2.0 with respect to 100 parts by weight of the total of the components.
Parts by weight Here, it is desirable that each of (A) the polyolefin polymer and (B) the polyolefin polymer modified with the unsaturated carboxylic acid or a derivative thereof is a propylene polymer. Further, (A) a polyolefin-based polymer has a melt flow rate (MFR _A), (B) a ratio of an unsaturated carboxylic acid or a melt flow rate of the modified polyolefin-based polymer with a derivative thereof (MFR _B) (M
FR _B / MFR _A) is desirably 50 or less. Further, (A) the polyolefin polymer is a propylene / ethylene block copolymer, and (B) the polyolefin polymer modified with an unsaturated carboxylic acid or a derivative thereof is a propylene homopolymer or a propylene / ethylene random copolymer. Desirably, it is a polymer. The resin material for blow molding of the present invention is characterized by comprising the above polyolefin-based resin composition.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the polyolefin polymer (A) used in the present invention, propylene homopolymer or ethylene, butene-1, pentene-1, hexene-1,4-methyl containing propylene as a main component is used. Penten-1,
Copolymer with one or more selected from heptene-1, octene-1, and decene-1, polyethylene-based polymer, poly-4-methylpentene-1, ethylene-propylene rubber, and a mixture of two or more thereof Is mentioned. Among them, a propylene polymer or an ethylene polymer is preferred. In particular, a block copolymer of propylene and ethylene is preferable particularly when used in a large blow molded product or the like because the molded product has an excellent balance between rigidity and impact resistance.

In the present invention, the polyolefin polymer (B) modified with an unsaturated carboxylic acid or a derivative thereof is propylene homopolymer or ethylene, butene-1, pentene-1 or hexene-containing propylene as a main component. Copolymer with one or more selected from 1,4-methylpentene-1, heptene-1, octene-1, and decene-1, polyethylene-based polymer, poly4-methylpentene-1, ethylene- Propylene rubber and their 2
A polymer obtained by graft-modifying the above mixture with an unsaturated carboxylic acid or a derivative thereof is exemplified. Among them, a polypropylene-based polymer or a polyethylene-based polymer is preferable, and a propylene homopolymer or a random copolymer obtained by adding propylene and ethylene or butene-1 or the like to them is most preferable. For example, a propylene homopolymer is suitable for a sheet composition for a large blow molding or a tray where heat resistance is required especially where a balance between rigidity and impact resistance is required, and a balance between impact resistance and workability is particularly required. For example, a random copolymer is suitable as a composition for a flexible container.

These polyolefin polymers are modified with unsaturated carboxylic acids or derivatives thereof. Unsaturated carboxylic acids or derivatives thereof are specifically acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid,
Itaconic anhydride, citraconic anhydride, citraconic anhydride, and the like can be mentioned. One or more compounds selected from these are added to the polyolefin-based polymer in an amount of 0.01 to 1% by weight.
It is modified by adding 0 wt% by a grafting method. Among them, modification with maleic anhydride is preferred. Regarding this modification, benzoyl peroxide, lauroyl peroxide, cumyl peroxide, 2,5-dimethyl-2,5- (t-butylperoxy) hexane, 1,3-bis (t (Butyl peroxyisopropyl) benzene or an organic peroxide of a mixture thereof is used. Usually, the amount is 0.005 to 3.0 with respect to 100 wt% of the polyolefin polymer.
wt%. Although the modification method is not particularly limited, an unsaturated carboxylic acid or a derivative thereof and an organic peroxide are mixed with the polyolefin polymer, and after sufficient mixing and stirring, the melting point is equal to or higher than the melting point of the polyolefin polymer. ~
In addition to the method of melting and kneading at a temperature of 280 ° C. with an extruder or the like, for example, a method of blending the components with an organic solvent dissolving the polyolefin may be mentioned.

[0009] (A) a ratio of MFR of the polyolefin-based polymer (B) an unsaturated carboxylic acid or polyolefin-based polymer modified with a derivative thereof (MFR _B / MFR _A) is preferably 50 or less, more preferably Is 20 or less. The propylene homopolymer or propylene-based random copolymer particularly preferably used as the component (B) in the present invention increases the MFR when graft-modified, and further increases the MFR when trying to increase the graft ratio.
_B / MFR _A will have significant, typically, greater than 50. In the present invention, it is desirable to minimize the increase in MFR due to the visbreak of the polymer at the time of graft modification, and the ratio of the MFR of the component (A) to the component (B) (MFR _B
/ MFR _A ) is set to 50 or less, more preferably 20 or less, so that the resin composition of the present invention has a strain of 1.0 during elongation deformation.
Ratio (σ) between the stress value at 0 (σ ₁ ) and the maximum stress value (σ _max )
Of 2.9 or more is easily obtained. This is because viscoelastic characteristics can be improved by graft-modifying a component having a relatively large molecular weight in the resin composition.
In the present invention, MFR is based on JIS K6758,
It is measured under the conditions of 230 ° C. and a load of 2.16 kg.

In the resin composition of the present invention, the polyolefin-based polymer (A) is 99 to 1% by weight, preferably 90 to 1% by weight.
~ 50 wt%, most preferably 85-65 wt%,
(B) The polyolefin polymer modified with the unsaturated carboxylic acid or its derivative is blended in an amount of 1 to 99 wt%, preferably 10 to 50 wt%, most preferably 15 to 35 wt%. (A) polyolefin polymer is 9
When the content is 9 wt% or more, drawdown property at the time of molding processing is poor or puncturing tends to occur at the time of blow molding. If the content is less than 1 wt%, the balance between impact strength and rigidity may be poor. Further, when the content of the unsaturated carboxylic acid or its derivative in the whole composition is 0.005 to 5 wt%, preferably 0.01 to 1 wt%, the melt tension is further increased, which is particularly suitable for hollow molding applications. .

The hydrotalcite compound (C) in the present invention is a double salt compound represented by the following general formula (I). M _1-x Al _x (OH) ₂ A _y · sH ₂ O (I) Here, M is Mg, Ca or Zn, and A is an anionic oxide such as CO ₃ . x, y and s represent real numbers. Hydrotalcites may be either natural or synthetic, but a synthetic product in which M is Mg and A is CO ₃ is particularly preferred. As a specific example of such a thing, "DHT-
4A "(manufactured by Kyowa Chemical Industry Co., Ltd.). The compounding amount is 0.01 to 2.0 parts by weight, more preferably 0.1 to 1.0 parts by weight, based on 100 parts by weight of the total amount of the polyolefin polymer.

Hydrotalcite compounds are generally used as catalysts for neutralizing acidic catalyst residues in catalytic polymerization for synthesizing polyolefins and the like, but they are viscoelastic in the combination of polyolefin components in the present invention. It has not been known until now that a desirable effect should be exhibited. Although the mechanism of the expression is not clear at present, it is presumed that the contained metal ion is involved.

In the polyolefin resin composition of the present invention, the ratio (σ: σ _max / σ ₁ ) between the stress value (σ ₁ ) at the strain of 1.0 at the time of elongation and the maximum stress value (σ _max ) is obtained. It is 2.9 or more, more preferably 3.0 or more. If σ is not more than 2.9, the drawdown of the parison becomes large, and puncturing tends to occur during blow molding, and the resin composition is not particularly suitable for blow molding. In the present invention, a uniaxial elongational viscometer is used for elongation deformation, and a strain rate of 0.1 at 190 ° C.
It is measured from the stress-strain relationship in sec ^-1 . As the strain increases, the stress gradually increases, and the sample breaks after exhibiting the maximum stress. The distortion at this time is 1.0.
The ratio (σ) is obtained from the stress value (σ ₁ ) and the maximum stress value (σ _max ) at. In the present invention, component (A),
The order of blending (B) and (C) is not particularly limited as long as they are uniformly mixed. For example, stirring is performed for 3 minutes or more using a stirring device such as a Henschel mixer, a ribbon blender, or a tumbler. In order to melt-knead the mixture thus obtained, a conventional kneading device such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, and a kneader may be used.
Screw extruders are particularly preferred.

The resin composition of the present invention is a composition having improved viscoelastic properties and has an MFR of 0.5 g / 10 min or less.
Those using a propylene / ethylene block copolymer as the component (A) and an unsaturated carboxylic acid graft-modified propylene homopolymer as the component (B) are particularly suitable for large blowers used for applications such as large containers and panel-shaped hollow containers. It is suitable for molding, has excellent drawdown resistance of parison, has less uneven wall thickness, and provides a molded article having a good balance of impact resistance and rigidity. When a propylene / ethylene block copolymer is used as the component (A) and a propylene homopolymer or a propylene / ethylene random copolymer is used as the component (B), the copolymer is modified with an unsaturated carboxylic acid. It is because it is not a block copolymer, it does not cause gelation or reduction in rigidity or impact resistance, and because it contains a block copolymer,
It is preferable as a resin material for blow molding, and it is possible to mold a blow molded product having high strength. In the present invention, in addition to the above components, various coloring agents, ultraviolet absorbers, lubricants, antistatic agents, copper damage inhibitors, flame retardants, light stabilizers, organic fillers (eg, wood flour) commonly used in polyolefin resins, It is possible to further add an inorganic filler (eg, glass fiber, mica, etc.) as long as the original purpose is not impaired. These are the above (A), (B),
It may be blended at the time of melt-kneading the three components (C) or may be blended after the production of the composition.

[0015]

EXAMPLES Various measurements in the following examples were performed by the following measurement methods. MFR was measured according to JIS K6758. Melt tension (MT) was measured at 230 ° C. using a Capillograph (manufactured by Toyo Seiki). In addition, the orifice used the orifice of L / D same as MFR measurement. The rigidity of the pressed sheet was determined according to JIS K6758. Izod impact strength is JIS K675 for pressed sheet
Performed according to 8. The ratio (σ) was measured using a uniaxial elongational viscometer (manufactured by Toyo Seiki) at a temperature of 190 ° C. and a strain rate of 0.1.
The sample was subjected to elongation deformation at sec ⁻¹ , and a stress value (σ ₁ ) at a strain of 1.0 and a maximum stress value (σ _max ) indicated and measured were calculated.

Example 1 A propylene / ethylene block copolymer having an MFR of 0.35 g / 10 min and a propylene / ethylene copolymer component of 11% by weight was used as the component (A). As the component (B), the MFR is 0.45.
A mixture of benzoyl peroxide and lauroyl peroxide as organic peroxides (mixing ratio, 50:50) (100% by weight of maleic anhydride in 100% by weight of a propylene homopolymer of g / 10 minutes) (“Perroyl BL”) 0.4% by weight of Nippon Oil & Fats Co., Ltd.), and the mixture was stirred for 3 minutes with a Henschel mixer, followed by melt-kneading. Melt kneading is a bidirectional twin screw extruder (manufactured by Nakatani Machine Co., Ltd.)
And extruded at a cylinder temperature of 200 ° C., the graft ratio of maleic anhydride was 0.23 wt%, and the MFR was 5.23.
A pellet made of the modified polyolefin-based polymer of g / 10 minutes was obtained. (C) 0.2 parts by weight of DHT-4A and an appropriate amount of an antioxidant are added to 100 parts by weight of the mixed resin consisting of 80 wt% of the component (B) and 20 wt% of the component (B), Using a screw extruder (manufactured by Nakatani Machine Co., Ltd.), melt kneading was performed at a cylinder temperature of 200 ° C. to obtain a polyolefin resin composition. About the obtained polyolefin resin composition, the ratio of the maximum stress value to the stress value (σ), the melt tension (MT), the rigidity, and the Izod impact strength were measured. As a result, the obtained polyolefin resin composition had an MFR of 0.40 g / 10 min, a of 4.9, an MT of 18.0 g, a rigidity of 14,200 kg / cm ² , and an Izod impact value of not breaking. (NB).

Example 2 The procedure of Example 1 was repeated except that (C) DHT-4A in Example 1 was changed to 0.3 parts by weight.
A polyolefin resin composition was obtained. This polyolefin resin composition has an MFR of 0.37 g / 10 min and a of 5.
6, MT is 21.9g, rigidity is 14,300kg / cm
^{2. The} Izod impact value was NB. Example 3 A maleated graft propylene / ethylene block copolymer (MFR) was used as the component (B) in Example 1.
Was obtained in the same manner as in Example 1 except that 1.20 g / 10 minutes, the rubber component was 17%, and the graft ratio of maleic anhydride was 0.12%). The obtained polyolefin-based resin composition has an MFR of 0.31.
Although the surface was slightly roughened at g / 10 minutes, σ was 3.
0, MT is 10.4g, rigidity is 10,000kg / cm
^{2. The} Izod impact value was NB.

Example 4 A polyolefin resin composition was prepared in the same manner as in Example 1 except that propylene homopolymer (MFR: 0.45 g / 10 min) was used as the component (A). Obtained. The obtained polyolefin resin composition had an MFR of 0.39 g / 10 min, a σ of 4.7, and an MT of 1
The weight was 6.0 g, the rigidity was 17,800 kg / cm ² , and the Izod impact value was 2.5 kg · cm / cm ² . Example 5 An anhydride obtained by grafting propylene / ethylene block copolymer (MFR: 0.35 g / 10 min, propylene / ethylene copolymer component 11% by weight) and maleic anhydride by the same operation as in Example 1. A maleic anhydride grafted random copolymer (ethylene content: 7% by weight) having a maleic acid graft ratio of 0.25 wt% and an MFR of 5.6 g / 10 min was blended in the same manner as in Example 1, and then DHT-4A was added in an amount of 0.25%. By adding 2 parts by weight, a polyolefin resin composition was obtained. This polyolefin resin composition has σ of 3.0 and MT of 12.2.
g, rigidity is 8,300 kg / cm ² , and Izod impact value is NB.
And the drawdown resistance was also good. Example 6 A polyolefin resin composition was obtained in the same manner as in Example 1 except that (C) DHT-4A was changed to 0.1 part by weight. The obtained polyolefin resin composition had an MFR of 0.45 g / 10 min, a of 2.9, and an MT of 2.9.
Although it is not high at 11.3g, the rigidity is 14,800k
g / cm ² , and the Izod impact value was NB.

Comparative Example 1 The procedure of Example 1 was repeated except that the component (B) was changed to a propylene homopolymer not modified with an unsaturated carboxylic acid or a derivative thereof (MFR: 0.45 g / 10 min). In the same manner as in Example 1, a polyolefin-based resin composition was obtained. The resulting polyolefin resin composition had an MFR of 0.43 g / 10 min, a of 1.3, and an MT of 5.3.
3 g, stiffness of 14,300 kg / cm ² , Izod impact value of NB, small σ and MT, and poor drawdown resistance. Comparative Example 2 A polyolefin resin composition was obtained in the same manner as in Example 1 except that (C) DHT-4A in Example 1 was not added. The resulting polyolefin resin composition had an MFR of 0.52 g / 10 min, a of 2.7 and an MT of 7.
5 g, stiffness of 14,500 kg / cm ² , Izod impact value of NB, small σ and MT, and poor drawdown resistance. [Comparative Example 3] A propylene homopolymer having an MFR of 0.45 g / 10 min as the polyolefin polymer modified with the unsaturated carboxylic acid or a derivative thereof (B) in Example 1 was subjected to the same operation as in Example 1. Is grafted with maleic anhydride to obtain a maleic anhydride graft ratio of 0.35 wt%, MFR
Was changed to a polymer of 20 g / 10 min to obtain a polyolefin resin composition in the same manner as in Example 1. The MFR of the obtained polyolefin resin composition was 0.51 g.
/ 10 min, σ is 2.1, MT is 9.8 g, rigidity is 13,50
0 kg / cm ² , the Izod impact value was NB, the σ was small, and the drawdown resistance was poor. Comparative Example 4 A propylene homopolymer having an MFR of 0.45 g / 10 min was grafted with maleic anhydride by the same operation as in Example 1, and the graft ratio of maleic anhydride was 0.23 wt.
% And a MFR of 5.23 g / 10 min.
-4A was added in an amount of 0.2 part by weight to obtain a polyolefin resin composition. This polyolefin resin composition has a σ of 7.
0, MT 28.1g, rigidity 17,500kg / c
m ² , Izod impact value was 2.3 kg · cm / cm ² , and although moldability was good, impact strength was insufficient, and gel was generated, resulting in poor surface.

[0020]

[Table 1]

[0021]

According to the polyolefin resin composition of the present invention, a molded product having a high melt tension, excellent workability, a small parison drawdown, and a small thickness deviation can be obtained.
Moreover, a molded product with excellent impact resistance balance can be obtained,
It is suitable for sheet molding, especially for blow molding. In addition, since a metal ion crosslinking agent such as zinc acetate is not used, a device provided with anticorrosion treatment is not required, and a gel due to poor dispersion hardly occurs. In particular, when a propylene / ethylene block copolymer is used as the component (A) and a propylene homopolymer or a propylene / ethylene random copolymer is used as the component (B), gelation, rigidity, A resin material capable of molding a high-strength blow molded product without causing a reduction in impact properties.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C08L 53/00 C08L 53/00 // B29K 23:00 F term (reference) 4F208 AA03C AA03F AA03H AA11 AA20 AR17 AR18 LG01 4J002 BB01W BB07X BB09X BB20X BB21X BN05X BP02W DE286

Claims (5)

[Claims] 1. A ratio of a maximum stress value (σ _max ) to a stress value (σ ₁ ) at a strain of 1.0 at the time of elongation and deformation having the following components (A), (B) and (C). (Σ) is 2.9 or more, polyolefin resin composition characterized by the above-mentioned. (A) The polyolefin polymer is 99 to 1 wt%. (B) The polyolefin polymer modified with an unsaturated carboxylic acid or a derivative thereof is 1 to 99 wt%. (C) The hydrotalcite compound is composed of the component (A) and (A). B) 0.01 to 2.0 with respect to 100 parts by weight of the total of the components.
Parts by weight 2. The olefin polymer according to claim 1, wherein the polyolefin polymer (A) and the polyolefin polymer (B) modified with an unsaturated carboxylic acid or a derivative thereof are propylene polymers. 3. The polyolefin resin composition according to item 1. Wherein said (A) and the polyolefin polymer has a melt flow rate (MFR _A), and (B) an unsaturated carboxylic acid or modified polyolefin-based polymer has a melt flow rate at its derivative (MFR _B) Ratio (MFR _B
/ MFR _A) is a polyolefin-based resin composition according to claim 2, characterized in that it is 50 or less. 4. The polyolefin-based polymer (A) is a propylene / ethylene block copolymer, and (B)
The polyolefin resin composition according to any one of claims 1 to 3, wherein the polyolefin polymer modified with an unsaturated carboxylic acid or a derivative thereof is a propylene homopolymer or a propylene / ethylene random copolymer. object. 5. A resin material for blow molding, comprising the polyolefin resin composition according to claim 1.