JPH05163394A - Polypropylene resin composition excellent in clarity and flexibility - Google Patents

Abstract

PURPOSE:To improve clarity flexibility, chemical resistance, and impact strength by compounding a syndiotactic PP with a specific block copolymer. CONSTITUTION:5-70wt.% syndiotactic PP having a racemic pentad fraction of 60% or higher and a melt index of 0.1-100g/10min is melt mixed with 95-30wt.% block copolymer having an arom. monomer-based unit content of 10-40wt.% and consisting of arom. vinyl polymer blocks and hydrogenated conjugated diene polymer blocks.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene resin composition having excellent transparency and flexibility.

[0002]

2. Description of the Related Art Conventionally, various materials have been proposed and put into practical use as molding materials for obtaining transparent and flexible molded products in the fields of food packaging materials, medical instruments and the like.

Among them, the molding material using soft vinyl chloride is excellent in flexibility and transparency and is inexpensive. However, since soft vinyl chloride usually contains a large amount of plasticizer, the plasticizer gradually dissipates and hardens, especially in packaging bags, tubes, etc. made from sheet-shaped molded products. The plasticizer may migrate and cause hygiene problems. Further, if the vinyl chloride monomer remaining in the molded product is not extremely reduced, there is a risk of causing a sanitary problem.

In this regard, transparency without plasticizer,
As a molding resin composition having various physical properties such as flexibility, a hydrogenated block polymer obtained by further hydrogenating a block polymer such as styrene-butadiene-styrene block polymer and styrene-isoprene-butadiene copolymer is used as a base. A mixed resin prepared by blending isotactic polypropylene, ethylene-vinyl acetate copolymer resin, and ethylene acrylate has been proposed (for example, JP-A-54-88950, JP-A-58-215446, and JP-A-59-58).
74158). It is disclosed in these patents that a composition using an ethylene-propylene random polymer has excellent transparency.

On the other hand, since propylene has a high rigidity, it is necessary to add a large amount of rubber in order to enhance flexibility as a composition, and as a result, polypropylene's original excellent chemical resistance cannot be sufficiently exhibited. It was Further, when the amount of rubber is large, the surface becomes sticky, when processed into a film, a pellet, a bag, a tube or the like, blocking is likely to occur, and an appropriate antiblocking agent, an antiblocking agent, or a lubricant is kneaded into the resin composition, molding A method such as dusting on the surface of the product was necessary. When food, blood for transfusion and the like are filled in a container formed of the resin composition, the contents may be contaminated by additives such as an antiblocking agent, which is not preferable.

On the other hand, recently, when a vinyl chloride resin containing a large amount of chlorine is incinerated, chlorine gas is generated, and if it diffuses into the atmosphere, it may cause acid rain or the like, which may cause environmental damage on a global scale. It is suspected that there is a need for a vinyl chloride alternative that does not produce harmful gases when incinerated.

[0007]

That is, the present invention is
It is an object of the present invention to provide a resin composition which is excellent in chemical resistance, has no protrusion and migration of a plasticizer, etc., and does not generate harmful gas that adversely affects the environment during incineration and combustion and has excellent transparency and flexibility.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that syndiotactic polypropylene is produced from aromatic vinyl compound monomers and hydrogenated conjugated diene compound monomers. The present invention has been accomplished by discovering that a resin composition containing the following block copolymer rubber has excellent chemical resistance, does not generate harmful gas during combustion, and has excellent transparency and flexibility. That is, the present invention provides syndiotactic polypropylene (A) 5 to
Block polymer (B) comprising 70 wt% of a polymer of an aromatic vinyl compound and a hydrogenated conjugated diene polymer
A polypropylene resin composition comprising 95 to 30 wt%. In the resin composition of the present invention, syndiotactic polypropylene is used in an amount of 5 to 70 wt%, preferably 30 to 70 wt%. Below 5 wt%,
Inferior in chemical resistance and heat resistance. The transparency and flexibility of the resin composition obtained by using the syndiotactic polypropylene are superior to those using the conventional isotactic polypropylene. In addition, the one using the conventional isotactic ethylene-propylene block copolymer was remarkably lower in transparency than the one using the ethylene-propylene random copolymer, but the syndiotactic ethylene-propylene block copolymer was used. Even if a coalesce is used, it is sufficiently transparent. In addition, syndiotactic polypropylene, compared to isotactic polypropylene,
Since the rigidity is low, the amount of rubber added to polypropylene in order to obtain equivalent flexibility is small, and the decrease in chemical resistance due to the compounded rubber is less than that of conventional isotactic polypropylene. It is also inexpensive.

The syndiotactic polypropylene used in the present invention can be obtained as a high purity syndiotactic polypropylene by using the camiskey type catalyst disclosed in Japanese Patent Laid-Open No. 41303/1990, slurry polymerization method, bulk polymerization method. A large amount can be produced by either the polymerization method or the gas phase polymerization method. Furthermore, since the use of these catalysts makes it possible to easily produce a uniform random copolymer with a low propylene content α-olefin, which has been difficult with conventional catalysts for polymerizing isotactic polypropylene, When a uniform random copolymer with α-olefin having a propylene content is used, a polypropylene resin composition having more excellent transparency and flexibility than the case of using a propylene homopolymer can be obtained.

The racemic pentad (r) of syndiotactic polypropylene used as a material for the resin composition of the present invention.
rrr) fraction is preferably 60% or more, particularly preferably 8%.
If the content is 5% or more and less than 60%, the transparency is not a problem, but the heat resistance and the moldability are not so excellent. In the present invention,
In addition to syndiotactic homopolypropylene, it is also excellent in transparency even if it is a random or block copolymer of propylene and other α-olefins such as ethylene and butene, but particularly contains 0.2 to 6 wt% of ethylene. A random propylene-ethylene copolymer is particularly excellent in transparency.
The melt index of syndiotactic polypropylene is not particularly limited, but when the molding method using the obtained resin composition is an injection molding method, it is 2 to 100 g / 10 mi.
n, in the case of extrusion molding, the amount of 0.1 to 4 g / 10 min is preferable.

In the resin composition of the present invention, 95 to 30 wt% of a block copolymer comprising a polymer of an aromatic vinyl compound and a hydrogenated conjugated diene polymer is used. 9
If it exceeds 5 wt%, the heat resistance, chemical resistance, and moldability will deteriorate,
If it is less than 30 wt%, the flexibility of the obtained resin composition is insufficient.

In the resin composition of the present invention, examples of the hydrogenated product of the block copolymer comprising the aromatic vinyl compound polymer and the hydrogenated conjugated diene polymer include:
Examples of the rubber include hydrogenated diblock and triblock copolymers composed of a polymer composed of an aromatic monomer such as styrene, α-methylstyrene and chlorostyrene and a polymer composed of a conjugated diene monomer such as butadiene, isoprene and chloroprene. Be done. In particular, hydrogenated products of styrene-butadiene diblock copolymer (SEB), hydrogenated products of styrene-butadiene-styrene triblock copolymer (SEBS), hydrogenated products of styrene-isoprene diblock copolymer (SEP). ), A hydrogenated product of a styrene-isoprene-styrene triblock copolymer (SEP
S) is preferred.

In the present invention, the aromatic monomer is 10
It is preferable to use a rubber obtained by hydrogenating a block copolymer composed of a polymer of an aromatic vinyl compound of about 40 wt% and a hydrogenated conjugated diene polymer, and a rubber having an aromatic monomer of less than 10 wt% is hydrogenated. The obtained resin composition does not have excellent scratch resistance, and the resin composition exceeding 40 wt% has poor flexibility.

The resin composition of the present invention comprises a syndiotactic polypropylene, a polymer of an aromatic vinyl compound and a hydrogenated conjugated diene polymer within a range that does not significantly reduce transparency, chemical resistance and flexibility. A resin or rubber other than the hydrogenated product of the block copolymer may be added.
For example, ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), ethylene-butene rubber (EBM), propylene-butene rubber, low density polyethylene, high density polyethylene, linear low density polyethylene, ultra low density polyethylene, Examples thereof include ethylene-ethyl acrylate copolymer (EEA), ethylene-vinyl acetate copolymer (EVA), and polybutene.
The resin composition of the present invention has a plasticizer, an antiblocking agent, a lubricant, a crystal nucleating agent, an ultraviolet absorber, a heat stabilizer, if necessary, within a range that does not significantly adversely affect the contents when processed into a bag or the like. Various additives such as radiation resistant agents, dyes and pigments may be added.

To melt-knead the resin composition of the present invention,
After melt-kneading by a method such as a Banbury mixer, a co-kneader, an extruder, a heat roll, and a calender roll,
Subsequently, it can be formed into a sheet, a tube or a film, or can be pelletized in advance and then processed into a sheet, a tube or a film by an extruder or the like. Further, in the present invention, even if a large amount of syndiotactic polypropylene is added, since it has excellent transparency and flexibility, in a resin composition containing a large amount of polypropylene, even by a method such as injection molding, a sheet, a tube, It is possible to mold bags etc. and has excellent productivity.

[0016]

Embodiments will be described in more detail with reference to embodiments. The flexibility of the resin composition is determined by the flexural modulus according to ASTM D
Measured by -790 method, Izo impact strength at -40 ° C is measured by ASTM D-256 method (thickness 6 m
m, notch notch), transparency is measured by measuring the total light transmittance and haze of a sheet obtained by an injection molding method having a thickness of 2 mm,
Melt index is 230 ℃, 2.16kg / cm
^It was measured under the condition of ² .

Examples 1 to 3 Isobropyr (cyclopentadiphenyl) as a catalyst
Zirconium chloride and methylaluminoxane as a co-catalyst were used, and propylene gas was blown into toluene to polymerize syndiotactic homopolypropylene.
The melt index was 10 g / 10 min, and the syndiotactic pentad fraction was 92% (SPP-
1). 60%, 50, and 30% by weight of this resin as hydrogenated styrene-butadiene triblock copolymer (SEBS) "Clayton G-1652 (manufactured by Shell Chemical Co., Ltd.,
Melt index 1.9 g / 10 min, styrene content 29 wt%) 40, 50, 70% by weight, and Irganox 10 per 100 parts by weight of resin as an additive.
0.1 parts by weight of 10 and 0.05 parts by weight of ionol,
0.1 part by weight of calcium stearate was blended, sufficiently mixed by a Henschel mixer, and then melt-kneaded at a temperature of 190 ° C. by a twin-screw extruder to obtain extruded pellets.
Using the obtained pellets, an injection molding machine with a mold clamping pressure of 100 t has a thickness of 2 mm, and a length and width of 180 mm and 80 mm, respectively.
A sheet of mm was obtained, and after being molded, annealed at 50 ° C. for 20 hours, and then the flexural modulus, total light transmittance, and haze were measured. The compounding ratio and physical properties are shown in Table 1.

Comparative Example 1 The syndiotactic homopolypropylene used in Example 1 was melt-kneaded without blending SEBS to obtain pellets, and a sheet was formed. Various physical properties were measured in the same manner as in Example 1, but the flexural modulus was high and the flexibility was poor. Also,
The total light transmittance, haze, and Izo impact strength were also low, and the transparency was poor. The compounding ratio and physical properties are shown in Table 1.

Examples 4 and 5 Using the same catalyst and co-catalyst as in Example 1, propylene and ethylene were blown into toluene at a mixing ratio of 98: 2 wt to obtain a syndiotactic propylene-ethylene random copolymer ( Ethylene content 2.2 wt%, melt index 2.0 g / 10 min, SPP-2).
This polypropylene ethylene random copolymer 30,7
Hydrogenated styrene-isoprene-styrene triblock copolymer "Septon 2002" (Kuraray Co., Ltd., melt index 100 g / 10 mi
n, styrene content 30 wt%) 70, 30 wt
%, And melt-kneaded in the same manner as in Example 1 to form a sheet. The compounding ratio and physical properties are shown in Table-2.

Example 6 Using the same catalyst as in Example 1, propylene and hexene-1 were copolymerized in the presence of hexene-1 to give a hexene-1 content of 7.2% and a melt index of 10 g / 10.
min syndiotactic propylene-hexene-1
A random copolymer was obtained (SPP-3). 70 wt% of this random copolymer and 30 w of hydrogenated styrene-isoprene-styrene triblock copolymer used in Example 4
t% was blended and melt-kneaded in the same manner as in Example 1 to form a sheet. The physical property results are shown in Table 2.

Comparative Example 2 Isotactic propylene-ethylene random copolymer obtained by using ordinary AA type titanium trichloride and diethylalkylaluminum monochloride as a catalyst (ethylene content: 2.2 wt%, melt index: 1.5 g)
/ 10 min, IPP-1) was 70 wt% and the same SEPS as in Example 4 was used in an amount of 30 wt%, and melt kneading was performed in the same manner as in Example 4 to form a sheet. The flexural modulus was higher than that in Example 5, the flexibility was poor, and the light transmittance, haze, and Izod impact strength were poor. The compounding ratio and physical properties are shown in Table-2.

Examples 7 and 8 After homopolymerization in toluene using the same catalyst and promoter as in Example 1, 1/1 wt of propylene and ethylene was used.
Blowing a mixed gas of syndiotactic propylene-
An ethylene block copolymer was obtained (ethylene content 1
0.3 wt%, melt index 15.0 g / 10
min, SPP-4). This block polypropylene 6
Hydrogenated styrene-isoprene diene block copolymer (SEP) "Septon 1001" at 0,50 wt% (Kuraray Co., Ltd., melt index 0.1 g / 10 min,
A styrene content of 35 wt%) was mixed with 40 and 50 wt% and melt-kneaded in the same manner as in Example 1 to form a sheet. Although the propylene-ethylene block copolymer was used in this example, a sheet having excellent transparency was obtained. The compounding ratio and physical properties are shown in Table-3.

Comparative Example 3 Isotactic ethylene-propylene block copolymer polymerized using the same catalyst as in Comparative Example 2 (ethylene content 10.5 wt%, melt index 20 g /
10 minutes, IPP-2) was melt-kneaded in the same manner as in Example 6 to form a sheet. The transparency was low because it was block polypropylene. Moreover, the flexibility and the Izod impact strength were also poor. The compounding ratio and physical properties are shown in Table-3.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

The resin composition of the present invention has the same rubber content as that of the conventional isotactic polypropylene and the resin composition of the block block copolymer rubber composed of the aromatic vinyl compound and the hydrogenated conjugated diene. It has better transparency and flexibility. Further, since it has sufficiently excellent transparency and flexibility even when the amount of rubber compounded is small, it is possible to provide a material containing a large amount of polypropylene, having excellent chemical resistance, and having little blocking even without containing an antiblocking agent or the like. Further, unlike the vinyl chloride resin, the resin composition of the present invention does not generate a harmful gas such as a chlorine compound at the time of combustion, and thus has a low risk of environmental damage.

Claims (1)

[Claims] 1. A block polymer (B) comprising 5 to 70 wt% of syndiotactic polypropylene (A) and a polymer of an aromatic vinyl compound and a hydrogenated conjugated diene polymer (B) of 95 to 30 wt%. Characteristic polypropylene resin composition