JP2003000699A - Resin composition and articles for medical use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for medical use not only having kink resistance and heat resistance competitive with conventional soft polyvinyl chloride resins, but also being free of an elution of plasticizers, excellent in safety and causing no difficulties for waste disposal. SOLUTION: This resin composition for medical use comprises 78-99 wt.% of an ethylene and α-olefin copolymer where the number of carbons contained in α-olefin is 3-20, the content of α-olefin is 8-50 wt.%, the density is 0.85-0.90 g/cm<3> , and the ratio of the weight average molecular weight(MW) to the number average molecular weight(Mn) (Mw/Mn) is 1.5-2.5. and 1-22 wt.% of a polyolefin resin where according to a differential scanning calorimeter method(DSC method) melting temperatures at peak are 100-200 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a specific ethylene
The present invention relates to a medical resin composition composed of an α-olefin copolymer and a specific polyolefin resin, and a medical molded article such as a medical tube or a catheter composed of the resin composition.

[0002]

2. Description of the Related Art At present, a polyvinyl chloride resin is used as a soft resin material most often used for medical molded articles such as infusion sets. This is because the polyvinyl chloride-based resin has the advantages that its flexibility can be easily controlled by the type and addition amount of the plasticizer, that it has a transparent feeling, that it has excellent moldability, and that it is relatively inexpensive. It is due to having.

However, in recent years, in order to deal with environmental problems such as dioxins and endocrine disrupters, there has been a strong demand for a soft resin material that can substitute for a polyvinyl chloride resin.

Further, in an infusion set using an infusion tube made of polyvinyl chloride resin, there is a problem that a trace amount of drug may be adsorbed to the infusion tube. This is because a small amount of drug may be added to the infusion solution for treatment, but since polyvinyl chloride resin is a polar material,
Depending on the type of drug, the drug may be adsorbed to the infusion tube, and a predetermined amount cannot be administered to the patient. Further, there is a problem that the plasticizer contained in the polyvinyl chloride resin is eluted into the infusion solution or the like. Therefore, there is a strong demand for an infusion tube (infusion set) which is non-adsorbable to the polyvinyl chloride resin and which does not adsorb the plasticizer and does not elute the plasticizer.

From this point of view, as an alternative material to the polyvinyl chloride resin, for example, a polyolefin resin such as an ethylene / vinyl acetate copolymer, a polyethylene resin or a polypropylene resin is used for an infusion tube or an infusion bag. It is under consideration to be used (for example, JP-A-8-131537 and JP-A-2000-93490).

However, since the ethylene / vinyl acetate copolymer has polarity, an infusion tube made of the ethylene / vinyl acetate copolymer has the same problems as in the case of the infusion tube made of the polyvinyl chloride resin. To do. Further, the infusion tube made of polyethylene resin or polypropylene resin cannot be said to be satisfactory in terms of flexibility, kink resistance (folding resistance) and the like. Among polyethylene-based resins, low-density polyethylene resin has relatively good flexibility, but even infusion tubes made of low-density polyethylene resin do not have sufficiently high kink resistance and heat resistance. .

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has the same kink resistance and heat resistance as those of conventional soft polyvinyl chloride resins and elution of a plasticizer. It is an object of the present invention to provide, at low cost, a medical resin composition which does not have the above problem, is excellent in safety, and has no difficulty in disposal processing, and a medical molded article made of the resin composition.

[0008]

According to the present invention, the α-olefin has a carbon number of 3 to 20, and the α-olefin content is 8 to 5.
0% by weight, the density is 0.85 to 0.90 g / cm ³ , and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 1.5 to 2.5. Ethylene / α
-Olefin copolymer 78 to 99% by weight, and melting peak temperature by differential scanning calorimetry (DSC method) of 100 to 2
It is a medical resin composition comprising 1 to 22% by weight of a polyolefin resin at 00 ° C., and a polypropylene resin is particularly suitable as the polyolefin resin. Further, another aspect of the present invention is a medical molded article characterized by comprising the above-mentioned medical resin composition, and a preferable example of the medical molded article is a medical tube or catheter. Hereinafter, the present invention will be described in detail.

The α-olefin, which is one of the copolymerization components of the ethylene / α-olefin copolymer contained in the medical resin composition of the present invention, has 3 to 20 carbon atoms.
Those having 6 to 10 carbon atoms are preferably used. That is, 1-hexene, 4-methyl-1
-Pentene, 1-heptene, 1-octene, 1-nonene, 1-decene are preferably used. These α
-The olefins may be used alone or in combination of two or more. Among these α-olefins,
An α-olefin having 8 carbon atoms, that is, 1-octene is particularly suitable as a copolymerization component.

The ethylene-α-olefin copolymer contained in the medical resin composition of the present invention has an α-olefin content (α-olefin copolymerization ratio) of 8 to 50% by weight, preferably Is 10 to 45% by weight, more preferably 15 to 45% by weight. This is because if the α-olefin content is less than 8% by weight, the bending elasticity of the molded product becomes too large, and conversely, if it exceeds 50% by weight, the adhesiveness of the molded product becomes high.

The density of the ethylene / α-olefin copolymer contained in the medical resin composition of the present invention is 0.
It is limited to 85 to 0.90 g / cm ³ , and preferably 0.
87-0.90 g / cm ³ , more preferably 0.86-
It is 0.88 g / cm ³ . This has a density of 0.85 g /
This is because if it is less than cm ³ , the mechanical strength of the molded product becomes insufficient, and conversely, if the density exceeds 0.90 g / cm ³ , the flexibility and kink resistance of the molded product become insufficient. In addition, the said density is measured based on ASTM D792.

Further, the ethylene / α-olefin copolymer contained in the medical resin composition of the present invention has a ratio (Mw) of its weight average molecular weight (Mw) to its number average molecular weight (Mn).
/ Mn) is 1.5 to 2.5, and preferably 1.8 to 2.5. This is Mw
This is because that / Mn exceeds 2.5 is inferior in bending fatigue resistance and impact resistance of the molded product. The weight average molecular weight (Mw) and the number average molecular weight (Mn) are values measured by gel permeation chromatography (GPC).

The melt index (measured in accordance with ASTM D 1238) of the ethylene / α-olefin copolymer contained in the medical resin composition of the present invention is 0.3 to 3.0 g. / 10 minutes is preferable from the viewpoint of moldability and mechanical strength, and the melt flow rate (I ₁₀ / I ₂ : measured in accordance with ASTM D 1238) is 5.0 to 10.0. Is also preferable from the viewpoints of molding processability and mechanical strength.

The above ethylene / α-olefin copolymer can be obtained by copolymerizing ethylene and α-olefin using, for example, a metallocene catalyst.

The above metallocene catalyst is a compound in which at least one ligand having a cyclopentadienyl skeleton is coordinated with a metal of Groups 3 to 10 of the periodic table such as titanium or zirconium or a lanthanoid series metal, Specific examples thereof include, but are not particularly limited to, for example, cyclopentadienyl titanium tris (dimethylamide), methylcyclopentadienyl titanium tris (dimethylamide), bis (cyclopentadienyl) titanium dichloride, Dimethylsilyltetramethylcyclopentadienyl-t-butylamide zirconium dichloride, dimethylsilyltetramethylcyclopentadienyl-t-butylamide hafnium dichloride,
Dimethylsilyltetramethylcyclopentadienyl-p
-N-butylphenylamide zirconium chloride, methylphenylsilyltetramethylcyclopentadienyl-t-butylamide hafnium dichloride, indenyl titanium tris (dimethylamide), indenyl titanium tris (diethylamide), indenyl titanium tris (di- n-propyl amide), indenyl titanium bis (di-n-butyl amide) (di-n-propyl amide) and the like. These metallocene catalysts may be used alone or in combination of two or more kinds. A cocatalyst such as methylaluminoxane or a boron compound may be used in combination with these metallocene catalysts.

The method for copolymerizing ethylene and α-olefin to obtain the ethylene / α-olefin copolymer used in the present invention is not particularly limited, but for example, a solution using an inert medium is used. Examples of the polymerization method include a bulk polymerization method and a gas phase polymerization method in which an inert medium does not substantially exist, and any polymerization method may be adopted.

With the above catalyst and polymerization method, a density of 0.
85 to 0.90 g / cm ³ , and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 1.5 to
A substantially linear ethylene / α-olefin copolymer having a value of 2.5 can be obtained.

In addition to the above ethylene / α-olefin copolymer, the medical resin composition of the present invention has a melting peak temperature of 100 to 20 by differential scanning calorimetry (DSC method).
It contains a polyolefin resin at 0 ° C. The melting peak temperature measured by the differential scanning calorimetry (DSC method) is JI
It is measured according to SK 7121. The polyolefin-based resin used is limited to one having a melting peak temperature of 100 to 200 ° C. by the DSC method in order to enhance the heat resistance of the molded product and the molding processability.

Examples of the polyolefin resin include polyethylene resin, polypropylene resin, polybutene resin and methylpentene resin.

Examples of the above-mentioned polyethylene resin include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene / propylene copolymer, ethylene / (meth) acrylic acid copolymer, ethylene. Examples thereof include (meth) acrylic acid ester copolymers and ethylene / vinyl acetate copolymers.
Examples of polypropylene resins include homopolypropylene, block polypropylene, random polypropylene, propylene / α-olefin copolymer, propylene / ethylene copolymer, propylene / butene copolymer, propylene / ethylene / butene copolymer. And so on. In the resin composition of the present invention, among these polyolefin-based resins, polypropylene-based resins are particularly preferably used in order to exhibit good heat resistance.

The resin composition of the present invention comprises the above ethylene / α
-Olefin copolymer 78 to 99% by weight and the above polyolefin resin 1 to 22% by weight, more preferably the above ethylene / α-olefin copolymer 78 to 8
It is composed of 5% by weight and 15 to 22% by weight of the polyolefin resin. This is because if the proportion of the ethylene / α-olefin copolymer is less than 78% by weight, the kink resistance decreases, and conversely, if it exceeds 99% by weight, the heat resistance decreases. The ethylene / α-olefin copolymer and the polyolefin resin may be used alone or in combination of two or more.

The method for producing the medical resin composition of the present invention comprises:
It is not particularly limited, for example, using an ordinary kneader such as a stirring kneader, an extruder, a Banbury mixer, or a roll, the above-mentioned ethylene / α-olefin copolymer and the above polyolefin-based resin which are essential components Each predetermined amount,
One or two of various additives that are added as needed
A desired medical resin composition can be obtained by uniformly kneading each of the predetermined amounts of at least one kind at room temperature or under heating.

In the medical resin composition of the present invention, if necessary, for example, a filler, a bulking agent, a softening agent, a surfactant,
One or more of various additives such as coupling agents, antioxidants (anti-aging agents), heat stabilizers, light stabilizers, UV absorbers, colorants, lubricants, antistatic agents, flame retardants, etc. are added. It may be done.

The method for producing the molded article of the present invention is not particularly limited, and may be, for example, an extrusion molding method, a calender molding method, or the like, depending on the kind and intended use of the desired molded article.
A desired molded product can be obtained by adopting a normal molding method such as a press molding method and an inflation molding method and molding conditions accompanied therewith.

The form of the above-mentioned molded product is not particularly limited, and examples thereof include film or sheet-like products, bottles, tubes, box-like products, and the like, although the use is not particularly limited, but medical tubes or catheters. Etc. are preferable, and particularly suitable as a tube for an infusion set.

[0026]

EXAMPLES The following examples are given to illustrate the present invention in more detail, but the present invention is not limited to these examples.

(Examples 1 to 3 and Comparative Examples 1 and 2) Using a resin composition prepared by mixing the various resins shown below in the proportions shown in Table 1, an inner diameter of 3.0 mm and an outer diameter were measured by an extrusion molding apparatus. A 4.0 mm tube of each of Examples 1 to 3 and Comparative Examples 1 and 2 was molded.

Ethylene / α-olefin copolymer (Table 1
Resin A): The α-olefin has 8 carbon atoms, the α-olefin content is 20% by weight, and the density is 0.868 g / cm 3.
³ , Mw / Mn is 2.1, melt index is 0.5
g / 10 minutes, melt flow rate (I ₁₀ / I ₂ ) 7.
6, ethylene / 1-octene copolymer polyolefin resin (resin B in Table 1) having a melting peak temperature of 67 ° C. according to the DSC method: density of 0.
91 g / cm ³ , melting peak temperature by DSC method is 13
Random polypropylene polyvinyl chloride resin (resin C in Table 1) at 5 ° C .: 100 parts by weight of polyvinyl chloride having an average degree of polymerization of 1000 and 50 parts of a plasticizer
Soft polyvinyl chloride resin made by adding parts by weight

The performances ((1) kink resistance, (2) heat resistance) of the tubes of Examples 1 to 3 and Comparative Examples 1 and 2 were evaluated by the following methods. The results are shown in Table 1.

(1) Kink resistance FIG. 1 is a schematic diagram showing a compression tester for evaluating kink resistance. From chuck distance 50mm to compression speed 1
Compress the tube under the condition of 00 mm / min, and
(Chuck movement distance: mm) was obtained and used as an evaluation value of kink resistance. In addition, the said evaluation was performed in 25 degreeC-50% RH atmosphere.

(2) Heat resistance Each tube was placed in an oven set at any of 60, 70, 80, 90 and 100 ° C. for 1 hour, and the heat resistance was evaluated by the presence or absence of deformation of the tubes. In Table 1, the results are shown as ◯: no deformation was observed in the tube, and x: deformation was observed in the tube.

[0032]

[Table 1]

From Table 1, the tubes of the present invention (Examples 1 to 1)
It can be seen that 3) exhibits the same kink resistance and heat resistance as the tube made of the conventional polyvinyl chloride resin (Comparative Example 2). Moreover, the tube of the present invention (Examples 1 to 3)
It can be seen that is particularly excellent in kink resistance as compared with the tube of Comparative Example 1.

Next, the resin compositions of Examples 1 to 3 were subjected to two items of safety tests by the following method.

(1) Elution test "Sterilized infusion set standard, etc." (Pharmaceutical Medicine No. 1079, 1998) sterilized infusion set standard 6.1
According to the eluate test, the eluate test was performed with a sample collection amount of 10 g. As a result, it was confirmed that each of the test items for pH, heavy metals, potassium permanganate reducing substances, and evaporation residues met the standards.

(2) In accordance with the cytotoxicity test "Guidelines for Basic Biological Tests for Medical Devices and Medical Materials" (Attached to Yakuki No. 99, 1995),
A colony formation inhibition test was performed. As a result, the colony formation rate in the sample solution and the negative control test solution was not particularly decreased with respect to the blank extraction test solution, and it was considered that the sample did not show cytotoxicity.

From the above, it is clear that the resin composition and molded article of the present invention have excellent safety for medical use.

[0038]

EFFECTS OF THE INVENTION Since the present invention has the above-mentioned constitution, it is excellent in kink resistance and heat resistance as well as in safety. Furthermore, there is no problem of elution of the plasticizer, and there is no difficulty in disposal. It is also possible to perform EOG sterilization or γ-ray sterilization. Therefore, the resin composition of the present invention,
In particular, it is extremely useful as a medical tube or catheter.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a compression tester for evaluating kink resistance.

FIG. 2 is a diagram showing a method for obtaining a value (L) indicating kink resistance.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 23:10) C08L 23:00 (C08L 23/16 23:00) F term (reference) 4C066 FF01 JJ10 4C081 AC07 AC08 BA15 BB03 BB07 BC03 CA021 CC01 DA03 4J002 BB00X BB03X BB05W BB06X BB07X BB08X BB12X BB14X BB15W BB15X GB01

Claims (4)

[Claims] 1. An α-olefin having 3 to 20 carbon atoms, α
-Olefin content 8-50% by weight, density 0.85
˜0.90 g / cm ³ , and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 1.5 to
2.5 ethylene / α-olefin copolymer 78
To 99% by weight, and a polyolefin resin 1 to 22 having a melting peak temperature of 100 to 200 ° C. by differential scanning calorimetry (DSC method)
A resin composition for medical use, characterized in that the composition is made up by weight. 2. The medical resin composition according to claim 1, wherein the polyolefin resin is a polypropylene resin. 3. A medical molded article, comprising the medical resin composition according to claim 1 or 2. 4. The medical molded article according to claim 3, wherein the medical molded article is a medical tube or a catheter.