JPH07145280A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE:To obtain a polypropylene resin composition having excellent strength, rigidity, heat-resistance and moldability and low specific gravity. CONSTITUTION:This polypropylene resin composition is produced by adding (A) 5-50 pts.wt. of a fibrous and/or flaky filter to 100 pts.wt. of a mixture composed of (B) 50-95wt.% of a polypropylene and (C) 5-50wt.% of an ethylene-vinyl alcohol copolymer having an ethylene content of 25-50mol%. In the above composition, the MFR of the component B is 10-300g/10min and the melt viscosity of the component C (eta(C)) and that of the component B (eta(B)) satisfy the relationship eta(C)/eta(B)<=3 under the melt-kneading condition in the preparation of the above composition.

Description

Detailed Description of the Invention

[0001]

The present invention relates to strength, rigidity, heat resistance,
The present invention relates to a polypropylene resin composition having excellent moldability, and more specifically, a specific polypropylene compounded with a specific ethylene-vinyl alcohol copolymer (hereinafter abbreviated as EVOH) and a fibrous and / or plate-shaped filler. The present invention relates to the polypropylene resin composition.

[0002]

2. Description of the Related Art Polypropylene is widely used for various molded products, films, sheets, etc. because it has excellent moldability, mechanical properties, electrical properties, water resistance, chemical resistance, etc., low specific gravity and low cost. ing. However, polypropylene is not so high in heat resistance and rigidity, and it is desired to further improve them in order to develop new applications.

In order to solve these problems, attempts to improve heat resistance and rigidity by adding a filler such as talc or glass fiber to polypropylene have been widely made. However, in the composition obtained by such a method, although the effect of improving heat resistance and rigidity is recognized, as a result of adding a large amount of an inorganic filler having a large specific gravity, not only the specific gravity becomes large, but also the impact resistance is high. There is a drawback that the moldability is deteriorated and the fluidity at the time of melt processing is deteriorated, resulting in poor moldability.

Further, it has been proposed to blend modified polypropylene and polyvinyl alcohol or EVOH with polypropylene for the purpose of improving the rigidity of polypropylene (JP-A-58-122950). However, the above-mentioned composition has the drawbacks that the effect of improving rigidity and heat resistance is small, the fluidity is lowered, and the moldability is poor.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a polypropylene resin composition which solves the above-mentioned drawbacks of the prior art and is excellent in strength, rigidity, heat resistance and moldability and has a low specific gravity.

[0006]

That is, the present invention comprises (A) 50 to 95% by weight of polypropylene and (B) 5 to 50% by weight of an ethylene-vinyl alcohol copolymer having an ethylene content of 25 to 50% by mole. 5 to 50 parts by weight of the fibrous and / or plate-like filler (C) per 100 parts by weight of the mixture.
(A) melt flow rate (MFR, temperature 230 ° C., load 216)
(Value measured under 0 g) is 10 to 300 g / 10 minutes, and the melt viscosity η _{(B) of the} component (B) under the melt-kneading conditions when preparing the composition is the melt viscosity η of the component (A).
_With respect to _(A) , the present invention relates to a polypropylene resin composition η _(B) / η _(A) ≧ 3 (1), which satisfies the following formula (1). The present invention will be described in detail below.

The polypropylene used as the component (A) in the composition of the present invention has a temperature of 230 ° C. and a load of 2160 g.
Melt flow rate (MFR) measured below is 10
It is necessary to be ~ 300 g / 10 minutes. When the MFR is less than 10 g / 10 minutes, not only the molding processability is poor, but also the effect of improving mechanical properties and heat resistance in blending with EVOH and a filler is poor, which is not preferable.
On the other hand, if the MFR exceeds 300 g / 10 minutes, the mechanical properties of polypropylene itself will deteriorate, and even if blended with EVOH and a filler, the effect of improving the various properties aimed at by the present invention is not sufficiently observed. Becomes

Further, the polypropylene used in the present invention is a crystalline polymer basically consisting of propylene units, but optionally other monomer units, especially ethylene and / or 4 to 6 carbon atoms. One or more α-olefins can be included in an amount of 40 mol% or less. Particularly in the present invention, stereoregular homopolypropylene, a block propylene copolymer containing 0.5 to 30 mol% of ethylene and 0.1 to 30 of ethylene.
A random propylene copolymer containing mol% is preferably used.

The amount of polypropylene as the component (A) to be blended can be selected in the range of 50 to 95% by weight, preferably 55 to 90% by weight, based on the total mixture of polypropylene and EVOH. When the blending ratio is less than 50% by weight, the specific gravity of the resulting composition becomes large and the fluidity is lowered, which is not preferable, and when it exceeds 95% by weight, the desired effect of improving various properties becomes insufficient, which is preferable. Absent.

Next, EVOH used as the component (B) in the composition of the present invention is obtained by saponifying an ethylene-vinyl ester copolymer. Here, vinyl acetate is a typical vinyl ester, but other fatty acid vinyl esters (vinyl propionate, vinyl pivalate, etc.) can also be used. In the present invention, the ethylene content in EVOH is 25
It is important to be ˜50 mol%, and EVOH containing 27 to 45 mol% ethylene is more preferably used. If the ethylene content is less than 25 mol%, the molding processability of the obtained composition is deteriorated, which is not preferable.
If it exceeds mol%, the effect of improving strength, rigidity and heat resistance becomes poor, which is not preferable. The saponification degree of the vinyl ester component is preferably 96% or more, more preferably 99% or more.

Further, as the EVOH used as the component (B) in the present invention, the melt viscosity η _(B) under the melt-kneading condition when preparing the composition of the present invention is the component (A) under the same condition. For the melt viscosity η _{(A) of} polypropylene, it is necessary to satisfy the following formula (1).

Η _(B) / η _(A) ≧ 3 (1) That is, the melt viscosity of EVOH which is the component (B) is three times or more that of polypropylene which is the component (A). It is extremely important for achieving the effect. The reason for this has not been clarified in detail at present, but the condition of the formula (1) is probably used in order that polypropylene having a low melt viscosity efficiently wraps the EVOH and stretches the EVOH into a layer or a mesh by shear stress. It is estimated that it will be necessary to be satisfied.

The blending ratio of EVOH which is the component (B) in the composition of the present invention is 5 to 50% by weight, preferably 10 to 45% by weight, based on the total amount of polypropylene and EVOH used. . 5% by weight
If less than, the effect of improving desired physical properties is not sufficient,
On the other hand, when it exceeds 50% by weight, the specific gravity increases and the fluidity decreases remarkably, which is not preferable.

Further, the filler as the component (C) in the composition of the present invention needs to be fibrous and / or plate-shaped. As the filler used here,
It does not matter whether it is an organic filler or an inorganic filler as long as it does not melt or plasticize under the temperature and shear stress at the time of melt kneading when preparing the composition of the present invention. Absent. Here, the fibrous or plate-like filler is a fibrous or plate-like filler having an aspect ratio of at least 1.5 or more, and a spherical or powdery filler having an aspect ratio of less than 1.5 is reinforced. Since it is inferior in effect, it is not preferable to use it in the present invention. The average particle size of the filler used in the present invention is not particularly limited, but is 0.0
It is preferably 1 to 100 μm.

Specific examples of such a filler include glass fiber, asbestos fiber, carbon fiber, silica fiber,
Silica / alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, silicon carbide fiber, boron fiber, potassium titanate whiskers, zinc oxide whiskers, sepiolite, wollastonite, fibrous calcium carbonate and stainless steel, aluminum, Metallic fibers such as titanium, copper and brass, fibrous fillers such as aromatic polyamide fibers, aromatic polyimide fibers and aromatic polyester fibers, talc, mica, clay, glass flakes,
Examples include plate-like fillers such as various metal foils.

The mixing ratio of the filler as the component (C) is 5 to 50 parts by weight based on 100 parts by weight of the mixture of polypropylene used as the component (A) and EVOH used as the component (B). If the compounding ratio of the filler is less than 5 parts by weight, the effect of improving various properties aimed at by the present invention is not sufficient, while if it exceeds 50 parts by weight, the specific gravity increases and the fluidity decreases, which is not preferable.

The composition of the present invention comprises the above (A), (B),
It is composed of the component (C), and the manufacturing method thereof is not particularly limited, and various methods such as solution blending and melt blending can be used, but melt blending is preferred from the viewpoint of easiness of operation. The kneading conditions are not particularly limited as long as they satisfy the above formula (1), but 180 to 2
It is preferable to melt-knead at a temperature of 80 ° C. for 30 seconds to 20 minutes at a shear rate of 50 to 500 sec ⁻¹ .

The kneading order is not particularly limited, and the components (A), (B) and (C) may be mixed and kneaded at the same time, or the components (B) and (C) may be kneaded in advance. It is also possible to carry out two-stage kneading, in which the component (A) is added afterwards and the mixture is kneaded again.

The polypropylene resin composition of the present invention may be provided with conventionally known additives such as lubricants, lubricants, nucleating agents, dyes, pigments, in order to impart desired properties to the polypropylene resin composition in a range not impairing its purpose. Release agents, antioxidants, heat stabilizers, weather (light) resistance improvers, thermoplastic resins and thermosetting resins other than the components (A) and (B), fillers other than the component (C), etc. You may mix.

The composition of the present invention can be used in various injection molding machines, melt extrusion molding machines, compression molding machines, blow molding machines, rotational molding machines and the like to prepare various molded products, films, sheets, tubes, bottles, It can be molded into cups.

[0021]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 19 As shown in Table 1, using a predetermined polypropylene as the component (A), a predetermined EVOH as the component (B), and a predetermined fibrous and / or plate-like filler as the component (C). Were pre-mixed at the ratio of Raboplast Mill (Toyo Seiki Co., Ltd.)
Was melt-kneaded under the conditions of Table 1 and Table 2 and then pulverized to obtain pellets. Using a small injection molding machine (Panajection manufactured by Matsushita Electric Industrial Co., Ltd.), the pellets were molded into a test piece at a cylinder temperature of 250 ° C. and a mold temperature of 60 ° C., and bending strength, bending elastic modulus, Izod impact strength, The heat distortion temperature and the specific gravity were measured. Moreover, MFR was measured using the pellet after kneading. The results are shown in Table 2. The above measurement was performed according to the following method.

Bending strength, flexural modulus: conforming to ASTM-D-790 Izod impact strength: conforming to ASTM-D-256 Heat distortion temperature (HDT): conforming to ASTM-D-648 MFR: conforming to ASTM-D-1238 According to ASTM-D-792, the composition of the present invention has a large flexural strength, a high flexural modulus, a high HDT and a high MFR. It is understood that the value is large, the moldability is excellent, and the specific gravity is low.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

Comparative Examples 1 to 3 Polypropylene alone was injection-molded under the same conditions as in the examples, and test pieces were prepared for characteristic evaluation. The results are shown in Table 7, which shows that the mechanical properties, although having a smaller specific gravity than the examples,
It can be seen that the thermal characteristics are inferior.

Comparative Examples 4 to 8 Predetermined polypropylene as the component (A) and predetermined EVOH as the component (B) were premixed at the ratios shown in Table 5, and then the Examples were carried out under the conditions shown in Table 5. Kneading and injection molding were carried out in the same manner as above, and a test piece was prepared and its characteristics were evaluated. The results are shown in Table 7. The specific gravity is small compared to the examples,
It can be seen that the fluidity is equivalent, but the mechanical properties and thermal properties are inferior.

Comparative Examples 9 to 11 Predetermined polypropylene as the component (A) and talc as the component (C) were mixed in advance in the proportions shown in Table 6, and then the same as the Examples under the conditions shown in Table 6. Then, kneading and injection molding were carried out to prepare test pieces, and the characteristics were evaluated. The results are shown in Table 8, and it can be seen that the flexural modulus decreases as compared with the examples when EVOH is not added.

Comparative Example 12 Premixed at a ratio shown in Table 6 using a predetermined polypropylene as the component (A), a predetermined EVOH as the component (B), and calcium carbonate as a spherical filler as the component (C). Under the conditions shown in Table 6, kneading and injection molding were carried out in the same manner as in the example, and a test piece was prepared to evaluate the characteristics. The results are shown in Table 8. When the filler having a small aspect ratio is used, the flexural modulus and the HDT may be reduced as compared with the system using the fibrous and / or plate-like filler as in the example. Recognize.

Comparative Examples 13 to 14 As shown in Table 6, using (A) component as a predetermined polypropylene, (B) component as EVOH or polyvinyl alcohol having ethylene content other than the present invention, and (C) component as talc. After premixing in a ratio, kneading and injection molding were carried out under the conditions shown in Table 6 in the same manner as in Examples,
A test piece was prepared and its characteristics were evaluated. The results are shown in Table 8. When EVOH other than those specified in the present invention is used as the component (B), the composition has inferior mechanical and thermal characteristics and fluidity as compared with the examples. When polyvinyl alcohol is used as the component (B), not only are the properties inferior to those of the examples, but also polyvinyl alcohol decomposes during kneading and molding, a large amount of gas is generated, and a bad odor is severe. Further, the obtained molded product was markedly colored.

Comparative Example 15 Polypropylene having MFR other than the present invention as the component (A), predetermined EVOH as the component (B), and talc as the component (C) were mixed in advance in the proportions shown in Table 6, Kneading and injection molding were performed under the conditions shown in Table 6 in the same manner as in the examples to prepare test pieces and evaluate the characteristics. The results are shown in Table 8. When polypropylene other than those specified in the present invention is used as the component (A), not only is the flowability inferior to that in the Examples, but the flexural modulus, HD
It can be seen that T also has a small improvement effect.

Comparative Example 16 Using polypropylene as a component (A), EVOH as a component (B), and talc as a component (C),
After premixing in the proportions shown in Table 6, the components (A) and (B) were kneaded under a kneading condition such that a melt viscosity ratio outside the scope of the present invention was obtained, and injection molding was carried out in the same manner as in Examples. Then, a test piece was prepared to evaluate the characteristics. The results are shown in Table 8, and it can be seen that the mechanical properties and thermal properties are inferior to those of the examples.

[0035]

[Table 5]

[0036]

[Table 6]

[0037]

[Table 7]

[0038]

[Table 8]

[0039]

As is apparent from the above description, the polypropylene resin composition of the present invention has excellent mechanical properties such as strength and rigidity and heat resistance, good moldability, and a relatively small specific gravity. Not only in applications where polypropylene has been used in the past, but also in applications that require heat resistance and rigidity that have been considered to be unusable with polypropylene,
It is expected to be able to develop applications. In addition, since the polypropylene resin composition of the present invention contains EVOH having a large polarity, it is expected to exert an effect in improving paintability and printability.

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Claims (1)

[Claims] 1. (A) 50 to 95% by weight of polypropylene,
(B) Ethylene having an ethylene content of 25 to 50 mol%
In a resin composition obtained by adding 5 to 50 parts by weight of (C) a fibrous and / or plate-like filler to 100 parts by weight of a mixture composed of 5 to 50% by weight of a vinyl alcohol copolymer, Melt flow rate (MFR, temperature 230 ℃, value measured under load 2160g) is 10
It is 300 g / 10 minutes, and the melt viscosity η _{(B) of the} component (B) under melt-kneading conditions when preparing the above composition is expressed by the following formula (1 _{) with} respect to the melt viscosity η _{(A) of the} component _(A). ) Is satisfied, the polypropylene resin composition characterized by satisfying. η _(B) / η _(A) ≧ 3 (1)