JP2005325333A - Polypropylene-based resin composition and outer cylinder of syringe made of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene-based resin composition whose transparency and impact resistance are simultaneously improved with a good balance and that has such an excellent property that its rigidity decrease is very low and whose impact resistance is hardly decreased by γ-ray irradiation and that is cheap, and to provide an outer cylinder of a syringe made of the resin composition. <P>SOLUTION: The polypropylene-based resin composition is produced by further control of total MFR(230°C) at 25-40 g/10 min by an added peroxide-induced thermal decomposition of a resin composition comprised of a 100 pts.wt. resin mixture, that comprises a 97-99.6 wt% polypropylene(A) whose MFR(230°C) is 4-20 g/10 min and ethylene content is 3.6-4.2 wt% and an 0.4-3 wt% ethylene/6-8C-α-olefin copolymer(B) whose MFR(190°C) is 2-6 g/10 min and density is not more than 0.850-0.870 g/cm<SP>3</SP>, and a 0.05-0.5 pts.wt. specified nucleus forming agent, and the outer cylinder of the syringe is made of the resin composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polypropylene resin composition excellent in transparency and impact resistance, and a medical instrument formed from the composition, particularly a syringe outer cylinder. More specifically, the present invention relates to a polypropylene-based resin composition that can withstand transportation after γ-ray or electron beam treatment and unexpected drop.

  In general, polypropylene resins are used in a wide range of applications including food containers and pharmaceutical containers because they are excellent in chemical characteristics, physical characteristics, and moldability, and are inexpensive. However, since the polypropylene resin itself does not necessarily have sufficient transparency and mechanical strength characteristics, various nucleating agents are usually added to the polypropylene resin to improve transparency and mechanical strength characteristics, and a large amount of rubber component is used. Although a method for improving impact resistance by adding is used, rubber is very expensive and expensive.

  As a known event, the composition described in Japanese Patent Application Laid-Open No. 2002-226649 was very expensive and could not satisfy transparency, impact resistance and rigidity at a low cost.

  A method of adding a nucleating agent to improve transparency, a method of adding an amorphous ethylene / propylene copolymer to impart impact resistance, or a propylene / ethylene block copolymer as a polypropylene resin In this method, it is difficult to satisfy all of them simultaneously, even if the performance of transparency, rigidity, or impact resistance can be achieved.

In addition, as a commonly used polypropylene for medical devices, an ethylene-propylene random copolymer having a high ethylene content is used, and medical devices using this are used for unexpected drops and needles after γ-ray sterilization. There was a problem that the impact resistance was extremely lowered by γ-rays at the time of wearing, and cracking occurred particularly in winter.
JP 2002-226649 A

  An object of the present invention is to provide a polypropylene-based resin composition that improves transparency, impact resistance, and rigidity, which could not be obtained conventionally, in a well-balanced manner and is excellent in economic efficiency. Another object of the present invention is to provide a polypropylene-based resin composition whose impact resistance is not easily lowered by electron beams or γ rays.

  A further object of the present invention is to provide a syringe outer cylinder that can be molded from a resin composition by injection molding into a syringe outer cylinder and that can solve the cracking problem even after sterilization with an electron beam or γ-ray.

In the present invention, (A) MFR (230 ° C.) is 4 to 20 g / 10 minutes, ethylene content is 3.6 to 4.2% by weight, polypropylene 97 to 99.6% by weight, (B) MFR (190 ° C. ) Is a copolymer of ethylene and an α-olefin having 6 to 8 carbon atoms having a density of 2 to 6 g / 10 min and a density of 0.850 to 0.870 g / cm ³ or less. And 0.05 to 0.5 parts by weight of a nucleating agent represented by the following formula (1) per 100 parts by weight of the resin mixture comprising: ° C) relates to a polypropylene resin composition having a molecular weight control of 25 to 40 g / 10 min.

  In the present invention, the polypropylene resin composition further comprises 0.05 to 0.3 parts by weight of a phosphorus antioxidant (C) and 0.01 to 0.3 parts by weight of an amine antioxidant (D). Provided is a polypropylene-based resin composition.

Furthermore, the present invention provides a syringe outer cylinder formed from the above-described polypropylene resin composition.

  The syringe barrel is particularly suitable for a syringe barrel that is sterilized by electron beam and γ-ray irradiation.

  In addition to maintaining such good transparency only in a very narrow composition range, it has been possible to develop an unprecedented material that can balance high impact resistance and rigidity after γ-ray irradiation and is low in cost. The impact resistance at 5 ° C. can be drastically improved, and it can solve the problem of cracking in winter and the problem of breakage at the time of wearing a needle, and this material is suitable for an inexpensive disposable syringe outer cylinder.

  The propylene-based resin composition according to the present invention and the syringe outer tube formed therefrom and suitable for use for sterilization by electron beam and γ-ray irradiation will be described more specifically.

The propylene-based resin composition of the present invention has (A) a melt flow rate MFR (230 ° C.) of 4 to 20 g / 10 min and an ethylene content of 3.6 to 4.2% by weight of 97 to 99.6% of polypropylene. %, (B) MFR (190 ° C.) of 2 to 6 g / 10 min and a density of 0.850 to 0.870 g / cm ³ or less of ethylene and an α-olefin having 6 to 8 carbon atoms. (C) 0.05 to 0.5 parts by weight of a nucleating agent represented by the formula (1) per 100 parts by weight of a resin mixture consisting of 0.4 to 3% by weight of a polymer and a peroxide A polypropylene resin composition characterized in that the molecular weight of the total MFR (230 ° C.) is further controlled to 25 to 40 g / 10 minutes by blending and thermal decomposition.

(A) Polypropylene (A) Polypropylene is a random copolymer of propylene and ethylene. The polypropylene has a melt flow rate value (MFR (230 ° C.)) of 4 to 20 g / 10 minutes, preferably 8 to 20 g / 10 minutes, and more preferably 8 to 12 g / 10 minutes. Further, it is desirable that the ethylene content measured by infrared absorption spectrum is 3.6 to 4.2% by weight, preferably 3.8 to 4.0% by weight.

  When the melt flow rate and the ethylene content are within the above ranges, the resin fluidity (moldability) and mechanical strength are well balanced, and a molded product having a good appearance can be obtained. When polypropylene having a melt flow rate of 4 or less is used, the appearance is not good due to a slight yellowishness due to resin oxidation deterioration. In addition, the amount of t-butanol generated according to the FDA standards is greatly increased, which is not preferable. Further, when the ethylene content is outside the above range, the balance between rigidity and impact resistance cannot be maintained.

Such polypropylene is produced in the required amount of propylene in the presence of a stereoregular olefin polymerization catalyst containing a transition metal compound component such as titanium or zirconium, an organoaluminum component, an electron donor, a carrier, etc., if necessary. It can be produced by polymerizing in the presence of the corresponding ethylene.

(B) Ethylene / α-olefin copolymer (B) The ethylene / α-olefin copolymer is a copolymer of ethylene and an α-olefin having 6 to 8 carbon atoms, and has a density of 0.850 to When it is 0.870 g / cm ³ and is within this range, the copolymer exhibits good rubber properties.

The melt flow rate value (MFR (190 ° C.)) of this copolymer (B) is 2 to 6, preferably 3 to 4 g / 10 minutes. Moreover, it is preferable that the density of this copolymer is 0.850-0.870 (g / cm < ³ >) especially. Within this density and MFR range, the copolymer is finely dispersed in the ethylene-polypropylene random copolymer while maintaining good rubber elasticity, and is excellent in transparency.

  Such an ethylene / α-olefin copolymer is a stereoregular polymerization such as a metallocene catalyst comprising a metallocene compound in which a compound having a cyclopentadiene skeleton is coordinated to a transition metal such as zirconium metal and an organoaluminum oxy compound. It can be produced by copolymerizing ethylene and an α-olefin in the presence of a catalyst. In particular, an ethylene / α-olefin copolymer produced using a metallocene catalyst is suitable as a raw material for a resin composition for containers because of its narrow molecular weight distribution and composition distribution.

In the present invention, a polypropylene resin composition in which the ethylene / α-olefin copolymer (B) is an ethylene / 1-octene copolymer is preferably used.

  In the present invention, a polypropylene resin composition which is a polymer produced by a metallocene catalyst is preferably used as the ethylene / α-olefin copolymer (B).

(C) Nucleating Agent As the (C) nucleating agent in the present invention, the organic phosphoric acid ester compound represented by the formula (1) described above is more suitable for the balance of physical properties and transparency.

Resin Composition The polypropylene resin composition of the present invention has a MFR (230 ° C.) of 4 to 20 g / 10 min and an ethylene content of 3.6 to 4.2% by weight of polypropylene (A) 97 to 99. Copolymerization of ethylene having 6 wt%, MFR (190 ° C.) of 2 to 6 g / 10 min and a density of 0.850 to 0.870 g / cm ³ or less and an α-olefin having 6 to 8 carbon atoms Peroxidation by adding 0.05 to 0.5 parts by weight of the nucleating agent (C) represented by the formula (1) per 100 parts by weight of the resin mixture consisting of 0.4 to 3% by weight of the union (B). The polypropylene resin composition, wherein the molecular weight of the total MFR (230 ° C.) was further controlled to 25 to 40 g / 10 min. When each component is within the above range, the transparency of the resin composition can be maintained at a high level, and at the same time, the impact resistance can be improved.

Since the polypropylene-based resin composition of the present invention performs molecular weight control by (F) peroxide described later, t-butanol is generated as a by-product. This t-butanol is characterized by being compliant with US Food and Drug Administration (FDA) standards by controlling it to 100 ppm or less by pellet drying at 110 ° C. for 12 hours.

Moreover, at the time of production of the polypropylene resin composition of the present invention described above, an embodiment which is a composition containing (D) a phosphorus antioxidant and / or (E) an amine antioxidant described later is preferable. MFR (230 ° C.) of 4 to 20 g / 10 minutes, ethylene content of 3.6 to 4.2% by weight of polypropylene (A) 97 to 99.6% by weight, MFR (190 ° C.) of 2 to 6 g / 10 And a copolymer (B) of ethylene and an α-olefin having 6 to 8 carbon atoms having a density of 0.850 to 0.870 g / cm ³ or less, and 0.4 to 3% by weight. The nucleating agent (C) is added in an amount of 0.05 to 0.5 parts by weight per 100 parts by weight of the resin mixture, and further the phosphorus antioxidant (D) is 0.05 to 0.2 parts by weight, preferably 0.1. -0.15 parts by weight, amine-based antioxidant (E) 0.01-0.1 parts by weight, preferably 0.03-0.06 parts by weight, and calcium stearate or hydrotalcite as a neutralizing agent 02 to 0.2 parts by weight, preferably 0.3 to 0.7 parts by weight, further peroxidation In particular, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane was added and the molecular weight was controlled by an extruder, and the total MFR (230 ° C.) was controlled to a molecular weight of 25 to 40 g / 10 minutes. Is a polypropylene resin composition characterized by

  When each component is within the above-mentioned blending range, the rigidity and transparency of the resin composition can be maintained at a high level, and at the same time, the impact resistance can be improved.

  The MFR (230 ° C.) of the polypropylene resin composition of the present invention is preferably 25 to 40 g / 10 minutes, more preferably 27 to 33 g / 10 minutes. If it is less than this, molding defects such as short shots and burning due to the need to raise the resin temperature will occur in the multi-cavity molding. Further, in the case of more than this, molding defects such as burrs and voids due to gas entrainment and impact resistance decrease are caused.

(D) Phosphorous antioxidant The (D) phosphorous antioxidant used in the present invention is not particularly limited, and a conventionally known phosphorous antioxidant can be used. In addition, it is preferable to use only one type of phosphorus-based antioxidant because the content contamination due to bleeding is small.

  The phosphorus-based antioxidant preferably used in the present invention is a trivalent organic phosphorus compound, specifically, tris (2,4-di-t-butylphenyl) phosphite, 2,2-methylenebis (4,6 -Di-t-butylphenyl) octyl phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, and the like.

(E) Amine antioxidant The (E) amine antioxidant used in the present invention is exemplified by a compound having a piperidine ring. Specifically, dimethyl succinate 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, bis (2,2,6,6-tetramethyl- 4-piperidyl) sebacate and the like are used.

(F) Peroxide The (E) peroxide used in the present invention is exemplified by 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane. Other examples include 1,3-bis (t-butylperoxy-isopropyl) benzene, but 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane is preferred because it is particularly for medical use. It is.

Syringe outer cylinder The polypropylene-based resin composition of the present invention has excellent properties in which the rigidity and transparency are kept at a high level, and at the same time, the impact resistance is improved, and even after γ-ray sterilization. Since it has high impact resistance, it can be used particularly as a syringe outer cylinder. In addition to this, the polypropylene resin composition of the present invention has productivity that cannot be achieved with conventional polypropylene, in which the impact resistance is hardly reduced even when treated with γ rays at low cost.

  Moreover, since this syringe outer cylinder is highly reducing the t-butanol which is a by-product in a polypropylene resin composition, t-butanol can also be produced in a syringe outer cylinder at 10 ppm or less, and is very safe. .

  The polypropylene resin composition of the present invention can be blended with additives such as a lubricant, if necessary, within a range not departing from the object of the present invention. In addition, when using as an electron beam or a gamma ray, for example, as a medical instrument, it is not recommended to add a phenolic antioxidant because it may turn yellow.

  If necessary, other additives and the like are mixed with each of the above components using a Henschel mixer, a V-type blender, a tumbler blender, a ribbon blender, etc., and then a single screw extruder, a multi screw extruder, a kneader, a Banbury mixer, etc. By melting and kneading using the above, it is possible to obtain a high-quality resin composition in which each component and additive are uniformly dispersed and mixed.

Syringe outer cylinder A syringe outer cylinder according to the present invention is a syringe outer cylinder manufactured from a resin composition containing the above-described components by means of injection molding and having excellent rigidity, transparency and impact resistance, and an electronic Even if sterilization treatment with wire or γ-ray is performed, the impact resistance is hardly lowered and the cost is low, which is unattainable with conventional polypropylene. It is particularly suitable for a disposable syringe that pursues high quality from this low cost.

  EXAMPLES Next, the present invention will be described through examples, but the present invention is not limited to the examples.

The raw materials used in the examples are as follows.
(A-1) Ethylene-propylene random copolymer:
MFR (230 ° C.); 12 g / 10 minutes Ethylene content; 4.0% by weight
(A-2) Ethylene-propylene random copolymer MFR (230 ° C.); 12 g / 10 minutes Ethylene content; 2.6% by weight
(A-3) ethylene-propylene random copolymer MFR (230 ° C.); 4 g / 10 min. Ethylene content; 4.0% by weight
(B-1) Ethylene / 1-octene copolymer:
MFR (190 ° C.); 4 g / 10 min Density; 0.860 g / cm ³
(B-2) Ethylene / 1-octene copolymer:
MFR (190 ° C.); 4 g / 10 minutes Density; 0.910 g / cm ³
(C-1) nucleating agent;
Hydroxyaluminum-bis [2,2-methylene-bis (4,6-di-t-butylphenyl) phosphate] (main component) Product name NA-21 (manufactured by Asahi Denka)
(C-2) nucleating agent;
Sodium-2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate [trade name: NA-11UY (Asahi Denka)]

In the present invention, physical properties were measured by the following methods.
(I) Haze: Measured using a 2 mm sheet in accordance with ASTM D1003.
(B) Bending elastic modulus: A bending test was performed according to ASTM D790, and the bending elastic modulus was calculated from the result.
(C) High-speed surface impact test: A striker with a load cell having a tip diameter of 1/2 inch is made to collide with a sample in a 5 ° C. atmosphere of a 2 mm thick square plate at a speed of 3 m / s. A base having a tip diameter (receiving diameter) of 3 inches was used as a receiving base on the back surface of the sample. As values, the total absorbed energy and the ductile energy from yielding to breaking were obtained.
(D) Tensile yield strength and elongation at break: A bending test was performed in accordance with ASTM D-638, and the tensile yield strength and elongation at break were measured from the results.
(F) Melt flow rate (MFR): Measured according to ASTM D-1238, with a load of 2.16 kg, and at the indicated temperature. For example, when measured at 190 ° C., MFR (190 ° C.) is displayed.

(Example 1)
In a Henschel mixer, 97 parts by weight of an ethylene-propylene random copolymer (A-1) and 3 parts by weight of an ethylene / 1-octene copolymer (B-1) were supplied, and a phosphorous antioxidant [Tris (2 , 4-di-t-butylphenyl) phosphite] 0.1 parts by weight, nucleating agent (C) 0, 25 parts by weight, calcium stearate 0.1 parts by weight, 2,5-dimethyl-2,5-di 0.03 part by weight of (tert-butylperoxy) hexane was added and mixed with stirring. The mixture was melt-kneaded at a resin temperature of 220 ° C. using a twin screw extruder (40 mmφ), and the kneaded product was extruded, cooled in water and cut to obtain a polypropylene resin composition pellet. The pellet was dried at 110 ° C. for 8 hours.

  Next, using the pellets, a sheet-shaped test piece having a thickness of 2 mm at 190 ° C. and a mold temperature of 40 ° C. by injection molding, a test piece for bending strength test (ASTM D790, thickness 3.2 mm, length 127 mm, width 12) And 7 mm), and Izod impact test specimens (ASTM D256, thickness 3.2 mm, length 63.5 mm, width 1.7 mm), respectively. These test pieces were irradiated with γ-rays of 20 kGy, and using this test piece, haze, bending elastic modulus, high-speed surface impact test absorbed energy, tensile yield strength and elongation at break were measured, and the results are shown in Table 1. .

(Example 2)
In Example 1, the blending amount of the ethylene-propylene random copolymer (A-1) is 98.5 parts by weight, and the blending amount of the ethylene / 1-octene copolymer (B-1) is 1.5 parts by weight. The procedure was the same as in Example 1 except for the change. The physical property measurement results are shown in Table 1.

(Example 3)
In Example 1, the blending amount of the ethylene-propylene random copolymer (A-1) was changed to 99 parts by weight, and the blending amount of the ethylene / 1-octene copolymer (B-1) was changed to 1 part by weight. The same operation as in Example 1 was performed. The physical property measurement results are shown in Table 1.

Example 4
In Example 1, it carried out like Example 1 except having changed the ethylene-propylene random copolymer (A-1) into the ethylene-propylene random copolymer (A-3). The physical property measurement results are shown in Table 1.

(Comparative Example 1)
Example 1 is the same as Example 1 except that the blending amount of the ethylene-propylene random copolymer (A-1) is 100 parts by weight without using the ethylene / 1-octene copolymer (B-1). The same was done. The physical property measurement results are shown in Table 1.

(Comparative Example 2)
In Example 1, except that the blending amount of the ethylene-propylene random copolymer (A-1) was changed to 95 parts by weight and the blending amount of the ethylene / 1-octene copolymer (B-1) was changed to 5 parts by weight. The same operation as in Example 1 was performed. The physical property measurement results are shown in Table 1.

(Comparative Example 3)
In Example 1, it carried out like Example 1 except having used ethylene-propylene random copolymer (A-2) instead of ethylene-propylene random copolymer (A-1). The physical property measurement results are shown in Table 1.

(Comparative Example 4)
In Comparative Example 3, except that the blending amount of the ethylene-propylene random copolymer (A-1) was changed to 90 parts by weight and the blending amount of the ethylene / 1-octene copolymer (A-2) was changed to 10 parts by weight. Performed as in Example 3. The physical property measurement results are shown in Table 1.

(Comparative Example 5)
The same procedure as in Example 1 was performed except that (C-2) was used instead of the nucleating agent (C-1) in Example 1. The physical property measurement results are shown in Table 1.

(Comparative Example 6)
In Example 1, it carried out like Example 1 except having used ethylene / 1-octene copolymer (B-2) instead of ethylene / 1-octene copolymer (B-1). The physical property measurement results are shown in Table 1.

  From the physical property measurement results shown in Table 1, it can be seen that the polypropylene resin composition according to the present invention has impact resistance while maintaining transparency, and those values are highly balanced. In the case of this resin composition, the cost increase is very small because a small amount of expensive rubber can be added. The impact resistance reduction after γ-ray irradiation is hardly seen, and the physical properties of the polypropylene resin composition that cannot be achieved at the conventional cost are shown, which is very useful.

In addition to maintaining such good transparency only in a very narrow composition range, it has been possible to develop an unprecedented material that can balance high impact resistance and rigidity after γ-ray irradiation and is low in cost. The impact resistance at 5 ° C. can be drastically improved, and it can solve the problem of cracking in winter and the problem of breaking at the time of wearing a needle, and this material is suitable for an inexpensive disposable syringe outer cylinder.

Claims (8)

(A) 97 to 99.6% by weight of polypropylene having an MFR (230 ° C.) of 4 to 20 g / 10 minutes, an ethylene content of 3.6 to 4.2% by weight,
(B) a copolymer of ethylene and an α-olefin having 6 to 8 carbon atoms having an MFR (190 ° C.) of 2 to 6 g / 10 min and a density of 0.850 to 0.870 g / cm ³ or less 0.4 to 3% by weight,
Per 100 parts by weight of the resin mixture consisting of
(C) 0.05 to 0.5 parts by weight of a nucleating agent represented by the following formula (1) was added, and the total MFR (230 ° C.) was further controlled to a molecular weight of 25 to 40 g / 10 minutes by peroxide. A polypropylene resin composition characterized by that.

The polypropylene resin composition according to claim 1, wherein the (B) ethylene / α-olefin copolymer is a polymer produced by a metallocene catalyst. Phosphorous antioxidant (D) 0.05 to 0.3 parts by weight and amine antioxidant per 100 parts by weight of the resin mixture comprising (A) polypropylene and (B) ethylene / α-olefin copolymer (E) The polypropylene-type resin composition of Claim 1 or 2 containing 0.01-0.3 weight part. A polypropylene resin composition, wherein a fatty acid metal salt is added to the resin composition according to any one of claims 1 to 3 as a dispersing agent of the formula (1). The polypropylene resin composition characterized by that t-butanol which is a by-product from the peroxide contained in the polypropylene resin composition according to any one of claims 1 to 4 is 100 ppm or less. A syringe outer cylinder comprising a composition formed from the polypropylene-based resin composition according to any one of claims 1 to 5 and formed by injection molding. 7. The medical disposable syringe outer cylinder according to claim 6, wherein the syringe outer cylinder is sterilized by electron beam irradiation, particularly γ-ray irradiation. A syringe outer cylinder, wherein t-butanol detected from the syringe outer cylinder according to claim 6 or 7 is 10 ppm or less.