JPH04282165A - Film or sheet for medical treatment - Google Patents

Abstract

PURPOSE:To provide the film or sheet for medical treatments which is made of polyethylene(PE), which is not deformed and has heat resistance even at a high sterilization temp. of 125 deg.C and can be easily heat sealed in spite of its having a crosslinked structure. CONSTITUTION:This film or sheet for medical treatments is obtd. by limiting the density and mol.wt. (MFR) of the PE, crosslinking this PE as a thick film or sheet and controlling the level of the crosslinking and has excellent heat resistance as well as heat sealing strength. The production of medical treating bags made of the PE having stable quality is possible and the high-temp. sterilization is possible as well.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention improves the heat resistance of polyethylene films or sheets that have excellent flexibility, transparency, and safety, and can be easily heat-sealed to achieve the practically necessary heat-seal strength. The present invention relates to a medical film or sheet having the following properties.

0002

2. Description of the Related Art Currently, in the medical field, hard containers made of glass, polyethylene, polypropylene, etc., and soft bags made of polyvinyl chloride containing a plasticizer are known. However, in the former case, when dropping the internal solution, air must be introduced using a vent needle or an infusion set with a ventilation hole, so there is a risk that the internal solution may be contaminated by the introduced air. On the other hand, the latter type of flexible bag does not require the introduction of air because the bag itself deforms due to atmospheric pressure as the contents drip, and it has become popular due to its safety and convenience in transportation and disposal after use. I'm starting. However, there is a problem in that plasticizers, additives, etc. contained in polyvinyl chloride as a raw material may be leached out.

[0003] In response, medical bags made from polyethylene have been proposed due to their flexibility, transparency, and safety, but due to their limited heat resistance, the sterilization temperature cannot be raised, and therefore Various measures have been required in the sterilization process, such as increasing the processing time or processing in a highly clean atmosphere. In addition, resins with high melting points among thermoplastic resins are examples of resins with high heat resistance, such as polypropylene (PP), which is approved by local laws and is used for hard containers, but it has low impact strength at low temperatures. Due to problems such as weakness, there are no examples of its use as a bag yet.

0004

[Problem to be solved by the invention] Generally, it is well known that polyethylene is crosslinked with radiation, etc. to improve its heat resistance, but this method is effective only for the purpose of improving heat resistance (shape retention). In such a case, the heat sealability in the next secondary processing step is significantly reduced, and the actual situation is that sufficient heat seal strength cannot be obtained. Furthermore, when heat-sealing a very thick film or sheet with a thickness of 100 to 800 μm as described in the present invention, when external heat is applied, the outer surface portion melts and the thickness of the sheet portion becomes extremely thin. This was a big problem as it reduced the seal strength of the bag. From the above, the present invention does not have these problems, namely, safety,
A medical film or film that not only has good hygiene properties, but also has excellent flexibility, transparency, and heat resistance that can withstand sterilization at high temperatures. Aim to get a seat.

[0005]

[Means for Solving the Problems] As a result of intensive research to solve the above problems, we have found that we have developed a method that is limited to particularly thick films or sheets, is limited in terms of materials, and has a gel content that indicates the degree of crosslinking. We found that this problem could be solved by controlling the rate. Based on this knowledge, the thickness is 100-800μ, the density is 0.890-0.935
g/cm3, melt flow index (MFR) 0
．． The present invention was completed by crosslinking a polyethylene film or sheet having a gel fraction of 1 to 8.0 g/10 minutes to a gel fraction in the range of 10 to 50%. The present invention will be explained in detail below.

(A) Polyethylene resin The polyethylene resin used in the present invention is polyethylene resin (I) or polyethylene resin (II) described below.
Each of these may be used alone or a mixture (composition) of both may be used. Therefore, the polyethylene resin of the present invention has a density of 0.89.
0 to 0.935g/cm3, preferably 0.8
90 to 0.930g/cm3, especially 0.890g/cm3
-0.927g/cm3 is suitable. Density is 0.8
Polyethylene with a density of less than 90 g/cm3 has not yet been generally produced industrially, and if it exceeds 0.935 g/cm3, the obtained film or sheet becomes extremely hard and also has a lower strength, which is not preferred in practice. Also, the melt flow index (hereinafter referred to as MFR) is 0.
．． 1 to 8.0 g/10 minutes, preferably 0.2 to 7
g/10 minutes, particularly preferably 0.3 to 5 g/10 minutes. If the MFR is less than 0.1 g/10 minutes, the processability during molding will be significantly reduced, and especially when molding a relatively thin film or sheet with a thickness of about 150 to 800 μm, the surface will become rough and it will not be possible to obtain a high quality product. Ta. Furthermore, when additives such as lubricants are added to improve processability, when the resulting product is used, it is undesirable because it dissolves into the content liquid and increases the number of fine particles. Furthermore, if the MFR exceeds 8.0 g/10 minutes, the processability is good, but the impact strength of the resulting film or sheet is so low that it is not suitable for practical use, and even if cross-linked with electron beams etc., there is no significant improvement in strength. was not seen.

[0007] The polyethylene resin (I) has 1 to 70 short chain branches per 1000 carbon atoms in the main chain,
The resin is a linear polyethylene resin or a linear low-density polyethylene resin having a density of 0.890 to 0.950 g/cm3. Both of these resins have ethylene and 3 carbon atoms.
It is widely produced industrially by copolymerizing ~12 (preferably 3 to 8) α-olefins in the presence of a so-called Phillips catalyst, Ziegler catalyst, or Ziegler catalyst. Preferred α-olefins include propylene, 1-butene, 1-hexene, 4-methylpentene-1, and 1-octene.

Polyethylene resin (II) is produced using a radical catalyst, and is generally produced by polymerizing ethylene under high pressure (usually 700 to 3000 kg/cm2). Widely used as polyethylene resin. This polyethylene resin (II) has a density of 0.915 to 0.93
0 g/cm3, and has long chain branches, and long chain branches have a length that can be sufficiently compared to the main chain, for example, carbon atoms of 15 or more (generally 30
It has more than one branch.

(B) Forming method of film or sheet The film or sheet of the present invention may be in the form of a tube, and methods for manufacturing them include water-cooled or air-cooled inflation method, T-die method, and the like. Further, the molding temperature must be set at a resin temperature at which the polyethylene resin of the present invention melts, and this temperature range is usually 1.
The temperature is 50 to 230°C (preferably 160 to 200°C). Also, the thickness of the film or sheet is 100 to 800μ
and preferably 150 to 700μ, especially 150μ
~500μ is suitable. If it is less than 100μ, the impact strength will be weak and there will be a practical problem, while if it exceeds 800μ, the flexibility will be significantly reduced and the practicality as a medical bag will be poor.

(C) Crosslinking method Irradiation was carried out using an electron beam irradiation device, model EPS-750 manufactured by Nissin High Voltage Co., Ltd. The accelerating voltage is 500kv and the dose is 5Mra.
d, the electron current is 4.93 mV, the velocity is 1.2 m/
The electron beam was irradiated at room temperature with an irradiation width of 116 cm and an irradiation atmosphere of air.

(D) Gel fraction measurement method Sample (3.5 x 3.5 cm;
film), and was heated under reflux with boiling toluene for 2 hours to perform extraction. Furthermore, the extraction residue after drying under reduced pressure was calculated as a weight percentage and was defined as a gel fraction.

(E) Heat-sealing method and heat-sealing strength measurement method The heat-sealing method for this film or sheet involves stacking two films or sheets, pressing them with heated plates from both sides, holding them for a few seconds, and then removing them. , can be easily heat-sealed by cooling. The sealing conditions used in this experiment were: sealing temperature 140°C, sealing pressure 3.0kg/cm2 (gauge pressure), and sealing time 2.
．． I did it in 5 seconds. A heat seal tester with a seal width of 3 mm and a top and bottom hot plate heating type manufactured by Tester Sangyo Co., Ltd. was used. On the other hand, the measurement of heat seal strength is based on JIS Z1
707.

(F) Manufacture of medical bags The obtained film, sheet, or tube-shaped object was subjected to high-pressure heat sterilization tests and to measure the drop strength of the film or sheet using the method used to manufacture ordinary bags. A medical bag can be manufactured by applying the method, appropriately forming a bag into a predetermined shape and size, and attaching a spout (spout). FIG. 1 is a front view of a typical medical bag using the film or sheet obtained according to the present invention. When manufacturing a medical bag using the film or sheet of the present invention, the upper fused portion 2 of the medical bag shown in FIG.
When providing the lower fused portion 3, the bag portion 1, and the spout 4, the sealing is performed by heat sealing, which is generally performed. Heat sealing involves heating two films or sheets with a seal bar from their respective outer surfaces, transmitting heat from both sides to the inner surfaces, and melting and fusing the inner surfaces. At this time, when heat sealing is performed at high temperatures, the outer surface easily melts and becomes fluid, resulting in an extremely thin film or sheet in the sealed area, which significantly reduces seal strength and bag drop strength. There was a problem that caused it to happen. However, with the crosslinked film of the present invention, even when heat-sealed at high temperatures, the rubber elasticity effect on the resin surface increases (increase in melt tension), preventing the above-mentioned deterioration of the sealed area. This is also a major feature of the present invention.

[0014]

[Examples] The present invention will be explained in more detail with reference to Examples below. In addition, in the examples and comparative examples, the density was determined at 23°C ± 0.1°C according to D method of JIS K7112.
Measured at a temperature of Also, the flexibility is ASTM D
-882, the tensile modulus was measured. Furthermore, the transparency is confirmed by high-pressure steam sterilization at 125℃ for 20 minutes after filling the contents, and after hot treatment at 40℃.
Haze according to STM D-1003 method
was determined and evaluated. Furthermore, the heat shrinkage rate is JIS Z1
709 at a temperature of 125° C. in the longitudinal direction.

Regarding the appearance, the appearance of wrinkles, deformation, and bag breakage was observed after heat sterilization using the method described above. Regarding drop strength, the medical bag shown in Figure 1 (width 140
mm, length 270 mm), filled with 500 cc of water, heat sterilized under the above conditions, and judged from the breakage of the bag when it was dropped from a height of 2 m onto a concrete surface.
Indicated by rank. ◎: Very good, ○: Good, △: Slightly poor, ×: Poor

[
The polyethylene resin (I) has 6 ethyl groups per 1000 carbon atoms in the main chain, and has MFR
is 1.0g/10min, and the density is 0.947g/cm3
A copolymer of ethylene and butene-1 (hereinafter referred to as "P")
E(a)"), and the number of butyl groups per 1000 carbon atoms in the main chain is 18, and the MFR is 4.0 g/10.
A copolymer of ethylene and hexene-1 (hereinafter referred to as "PE(b)") with a density of 0.921 g/cm3 and a density of 0.921 g/cm3.
and ethylene and butene-1, which have 48 ethyl groups per 1000 carbon atoms in the main chain, an MFR of 2.0 g/10 min, and a density of 0.895 g/cm3.
A copolymer of PE(c) (hereinafter referred to as "PE(c)") was used. For comparison, a copolymer of ethylene and butene-1 (hereinafter referred to as "PE(d)") has 5 ethyl groups per 1000 carbon atoms in the main chain and has an MFR of 12 g/10 min. )It was used.

The polyethylene resin (II) was manufactured by a so-called high pressure method using a free radical catalyst and had an MFR of 0.3 g/10 min and a density of 0.91.
7g/cm3 polyethylene resin (hereinafter referred to as “LDP”)
A polyethylene resin (hereinafter referred to as "LDPE (B)") with an MFR of 3.0 g/10 minutes and a density of 0.920 g/cm3 and MFR
is 5.0g/10min, and the density is 0.928g/cm
3 polyethylene resin (hereinafter referred to as "LDPE (C)")
) was used.

[0018] As a composition (mixture), each composition component was mixed in advance for 5 minutes using a Henschel mixer, and each of the obtained mixtures was kneaded using a single screw extruder (screw diameter 65 mmφ) at a resin temperature of 180°C. A pellet-like composition was produced. Table 1 shows the composition ratio and type of each composition component and the abbreviation of each composition obtained.

[0019]

[Table 1]

Tables 2 and 3 show the thickness of each film and sheet and the resin or composition used, and the molding method was a water-cooled inflation method (Examples 1 to 3).
6. Comparative Examples 1 to 6). In addition, Example 7 was obtained by the T-die method.
-10 and Comparative Examples 7-10 were molded.

[0021]

[Table 2]

[0022]

[Table 3]

From the results of the above examples and comparative examples, the medical film or sheet of the present invention not only has excellent flexibility and transparency, but also has heat resistance that can withstand sterilization at 125°C. It is clear that it has good heat sealability.

[0024]

According to the present invention, it is possible to produce polyethylene medical bags of stable quality that can withstand high temperature sterilization at 125°C.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a medical bag using the present invention.

[Explanation of symbols] 1 Bag part 2 Upper fusion part 3 Lower fused part 4 Pour inlet (spout) 5 Boundary line 5a End part 5b End part 6 Hanging hole 7. Fusion part

Claims (1)

[Claims] [Claim 1] Thickness 100-800μ, density 0.89
1.0 kg/15 mm by crosslinking a polyethylene film or sheet having a melt flow index (MFR) of 0 to 0.935 g/cm3 and a melt flow index (MFR) of 0.1 to 8.0 g/10 minutes to a gel fraction range of 10 to 50%. A medical film or sheet characterized by having a heat sealing strength greater than its width.