JP2003138459A - Polypropylene nonwoven fabric for medical application - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a radiation-proof nonwoven fabric of a polypropylene resin, which has sufficient mechanical properties and slight tackiness, less change in color and smell even by radiation exposure and can be used for medical application. SOLUTION: This polypropylene nonwoven fabric for medical application comprises a fiber made of a propylene/α-olefin random copolymer as at least one component, which is polymerized by a metallocene catalyst, has 10-2,000 g/10 minutes MFR, 1.5-4.0 Q value, <=10 deg.C T80 -T20 , <=3 wt.% soluble contents at 0 deg.C at TREF measurement and 1-18 mol % α-olefin contents.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene non-woven fabric for medical use, and more particularly to a polypropylene non-woven fabric for medical use which has little deterioration in mechanical properties even when exposed to radiation, and has little stickiness, discoloration or odor.

[0002]

2. Description of the Related Art Propylene-based resins such as polypropylene are excellent in moldability and rigidity, and also have excellent recyclability and heat resistance. Therefore, they are variously molded and processed like other resins such as polyvinyl chloride and polystyrene. It is widely used in various applications such as food containers, medical instruments, medical containers, and packaging films.

Nonwoven fabrics are used as medical instruments in a wide variety of fields such as surgical clothes, drapes, artificial dialysis and blood filtration filters, syringes and drug packaging. Most of these applications require sterilization. In the sterilization of medical instruments and medical containers, radiation sterilization has been performed for a long time, and γ-ray sterilization with Co ⁶⁰ is generally used, but since large-scale equipment is required, electron beam sterilization has become popular recently. It is starting.

By the way, since γ-ray sterilization is an electromagnetic wave having a high energy, when applied to a container using a propylene resin, deterioration of the propylene resin is promoted. In order to suppress this, adopt an additive formulation that uses a high molecular weight hindered amine or hindered phenol compound,
This has been dealt with by methods such as narrowing the molecular weight distribution of the polypropylene resin itself, or designing a polymer with low crystallinity by copolymerizing propylene and ethylene.

However, when an attempt is made to design such a polymer using a conventional Ziegler catalyst type propylene polymer, mechanical properties are deteriorated, and discoloration and odor of the product are caused. In addition, even in the case of low crystallization in which propylene and ethylene are copolymerized, the copolymerizability is not sufficient, and unless a considerable amount of ethylene is introduced, the crystallinity does not decrease, and there is a distribution in the crystallinity. ,
If the crystallinity is too low or the component is too high, the former causes stickiness, discoloration, and odor, and the latter interferes with radiation resistance, and the polypropylene resin with sufficient performance cannot be obtained. Had.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks, has little deterioration of mechanical properties even when irradiated with radiation, has little stickiness, discoloration, and odor, and can be used as a raw material for medical non-woven fabric. An object is to provide a radiation resistant nonwoven fabric of resin.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have made a propylene / α-olefin random copolymer having specific properties at least one component of constituent fibers. Non-woven fabrics are suppressed from being deteriorated in mechanical properties even when exposed to radiation, resulting in stickiness, discoloration,
The present invention has been accomplished by finding that it has a radiation resistance property with little odor and is suitable as a raw material for a nonwoven fabric for medical use.

That is, according to the first aspect of the present invention,
Polymerized by a metallocene catalyst, the following characteristics (1) to
There is provided a medical polypropylene-based nonwoven fabric comprising fibers containing at least one propylene / α-olefin random copolymer having (5). Characteristic (1): MFR is 10 to 2000 g / 10 minutes Characteristic (2): Q value is 1.5 to 4.0 Characteristic (3): T ₈₀ -T ₂₀ is 10 ° C or less Characteristic (4): During TREF measurement 0 ℃ soluble content of 3% by weight
Characteristic (5): α-olefin content is 1 to 18 mol% Characteristic (6): Tm is 110 to 140 ° C. (However, MFR is 230 ° C. according to JIS-K6921,
The melt flow rate at 21.18 N and the Q value are the ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mw measured by GPC, and T ₈₀ is the temperature rising elution fractionation (TR
In the integrated elution curve obtained by EF), the temperature at which 80% by weight is eluted, T ₂₀ is the temperature at which 20% by weight is eluted, and Tm is the peak temperature of the melting curve obtained by a differential scanning calorimeter (DSC). )

According to the second aspect of the present invention, the first aspect
Characteristics of the invention _{(3): T 80 -T 2} 0 is medical polypropylene nonwoven is provided, which is a 2 to 8 ° C..

According to a third aspect of the present invention, the first aspect
Or, the polypropylene-based nonwoven fabric for medical use is characterized in that the α-olefin of the propylene / α-olefin random copolymer described in the invention of 2 is ethylene and the content thereof is 1 to 12 mol%. .

According to a fourth aspect of the present invention, the first aspect
The medical treatment characterized in that the fiber containing at least one component of the propylene / α-olefin random copolymer according to any one of claims 1 to 3 is a single fiber, a core-sheath type composite fiber, or a side-by-side type composite fiber. Provided is a polypropylene-based non-woven fabric.

According to a fifth aspect of the present invention, the first aspect
The non-woven fabric made of fibers containing at least one component of the propylene / α-olefin random copolymer according to any one of items 1 to 4 is a spun bond method, a melt blown method,
Provided is a polypropylene non-woven fabric for medical use, which is a sheet-shaped non-woven fabric produced by either a hydroentangling method or a card method.

Further, according to the sixth aspect of the present invention, the strength retention rate before and after the electron beam irradiation of the nonwoven fabric subjected to the electron beam irradiation with the electron beam irradiation conditions of a voltage of 4.8 MeV, a current of 20 mA and a dose of 40 KGy. Is 70% or more, and a nonwoven fabric using the medical polypropylene-based nonwoven fabric according to any one of the first to fifth inventions is provided.

According to a seventh aspect of the present invention, the first aspect
A medical non-woven fabric obtained by subjecting the medical polypropylene non-woven fabric according to any one of claims 1 to 6 to radiation treatment is provided.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The propylene / α-olefin random copolymer used in the radiation-resistant propylene-based nonwoven fabric of the present invention is a copolymer polymerized using a metallocene catalyst. The metallocene catalyst is a catalyst that uses a complex of a transition metal of Groups 4 to 6 of the periodic table such as titanium, zirconium, and hafnium with a cyclopentadienyl group or a cyclopentadienyl derivative group.

In the metallocene catalyst, the cyclopentadienyl derivative group is an alkyl substituent such as pentamethylcyclopentadienyl, or two or more substituents are combined to form a saturated or unsaturated cyclic substituent. A group can be used, and typical examples thereof include an indenyl group, a fluorenyl group, an azulenyl group, and partial hydrogenated products thereof. Further, those in which a plurality of cyclopentadienyl groups are bound by an alkylene group, a silylene group, a germylene group or the like are also preferably used.

Specific examples of the metallocene complex include the following compounds. (1) Methylenebis (cyclopentadienyl) zirconium dichloride, (2) Methylene (cyclopentadienyl) (3,4-dimethylcyclopentadienyl) zirconium dichloride, (3) Isopropylidene (cyclopentadienyl) (3 , 4-Dimethylcyclopentadienyl) zirconium dichloride, (4) ethylene (cyclopentadienyl) (3,5-dimethylpentadienyl)
Zirconium dichloride, (5) methylenebis (indenyl) zirconium dichloride, (6) ethylenebis (2-methylindenyl) zirconium dichloride,
(7) ethylene 1,2-bis (4-phenylindenyl) zirconium dichloride, (8) ethylene (cyclopentadienyl) (fluorenyl) zirconium dichloride, (9) dimethylsilylene (cyclopentadienyl) (tetramethylcyclo Pentadienyl) zirconium dichloride, (10) dimethylsilylenebis (indenyl) zirconium dichloride, (11) dimethylsilylenebis (4,5,6,7-tetrahydroindenyl)
Zirconium dichloride, (12) dimethylsilylene (cyclopentadienyl) (fluorenyl) zirconium dichloride, (13) dimethylsilylene (cyclopentadienyl) (octahydrofluorenyl) zirconium dichloride, (14) methylphenylsilylene bis [1 -(2-Methyl-4,5-benzo (indenyl)]
Zirconium dichloride, (15) dimethylsilylene bis [1- (2-methyl-4,5-benzoindenyl)]
Zirconium dichloride, (16) dimethylsilylene bis [1- (2-methyl-4H-azurenyl)] zirconium dichloride, (17) dimethylsilylene bis [1-
(2-Methyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, (18) dimethylsilylenebis [1- (2-ethyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride , (19) Dimethylsilylenebis [1- (2-ethyl-4-naphthyl-4H-azulenyl)] zirconium dichloride, (20) Diphenylsilylenebis [1-
(2-Methyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, (21) dimethylsilylenebis [1- (2-methyl-4- (phenylindenyl))] zirconium dichloride, (22). Dimethylsilylenebis [1- (2-ethyl-4- (phenylindenyl))] zirconium dichloride, (23) Dimethylsilylenebis [1- (2-ethyl-4-naphthyl-4H-azulenyl)] zirconium dichloride, ( Two
4) dimethylgermylene bis (indenyl) zirconium dichloride, (25) dimethylgermylene (cyclopentadienyl) (fluorenyl) zirconium dichloride.

The same compounds as described above can be used for other Group 4, 5, and 6 transition metal compounds such as titanium compounds and hafnium compounds. These compounds may be used in combination with the catalyst component and catalyst of the present invention.

Further, compounds in which one or both of the chlorides of these compounds are replaced by bromine, iodine, hydrogen, methylphenyl, benzyl, alkoxy, dimethylamide, diethylamide and the like can be exemplified. further,
Instead of the above zirconium, compounds in which titanium, hafnium, etc. are replaced can be exemplified.

The cocatalyst comprises an ionic compound capable of reacting with an aluminum oxy compound or a metallocene compound to convert the metallocene compound component into a cation, a Lewis acid, a solid acid, or an ion-exchange layered silicate. At least one compound selected from the group is used. Moreover, an organoaluminum compound can be added together with these compounds as needed.

Examples of the aluminumoxy compound include methylalumoxane, ethylalumoxane, propylalumoxane, butylalumoxane, isobutylalumoxane, methylethylalumoxane, methylbutylalumoxane, methylisobutylalumoxane and the like.
It is also possible to use a reaction product of a trialkylaluminum and an alkylboronic acid. For example, a 2: 1 reaction product of trimethylaluminum and methylboronic acid, a 2: 1 reaction product of triisobutylaluminum and methylboronic acid, a 1: 1: 1 reaction product of trimethylaluminum and triisobutylaluminum and methylboronic acid, triethylaluminum and butylboron. 2: 1 reaction of acid and the like.

As the ion-exchange layered silicate, montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, stevensite,
A silicate such as a smectite group such as bentonite or teniolite, a vermiculite group, or a mica group is used.
It is preferable that these silicates have been chemically treated. Here, as the chemical treatment, both surface treatment for removing impurities adhering to the surface and treatment for affecting the crystal structure and chemical composition of the layered silicate can be used. Specifically, (a) acid treatment, (b) alkali treatment, (c) salt treatment, (d) organic substance treatment and the like can be mentioned. These treatments remove impurities on the surface, exchange cations between layers, and elute cations such as Al, Fe, and Mg in the crystal structure, resulting in ionic complexes, molecular complexes, organic derivatives, etc. Can be formed to change the surface area, interlayer distance, solid acidity, and the like. These treatments may be performed alone or two or more treatments may be combined.

If necessary, triethylaluminum, triisobutylaluminum,
Organoaluminum compounds such as diethyl aluminum chloride may also be used.

In the present invention, a propylene / α-olefin random copolymer is obtained by using the above metallocene catalyst. Examples of the α-olefin include α-olefins having 2 to 20 carbon atoms excluding propylene, and examples thereof include ethylene, butene-1, pentene-1,3-methyl-1-butene, hexene-1,3-methyl-1. -Penten, 4-
Methyl-1-pentene, heptene-1, octene-1,
Examples include nonene-1, decene-1, dodecene-1, tetradecene-1, hexadecene-1, octadecene-1, eicosene-1. Α-copolymerized with propylene
The olefins may be used alone or in combination of two or more.
Of these, ethylene and butene-1 are preferable, and ethylene is particularly preferable.

As the polymerization method, in the presence of these catalysts,
Examples thereof include a slurry method using an inert solvent, a gas phase method or a solution method substantially using no solvent, and a bulk polymerization method using a polymerization monomer as a solvent.

The propylene / α-olefin random copolymer used in the present invention is a copolymer polymerized by the above-mentioned metallocene catalyst and must have the following properties (1) to (6). is there. Hereinafter, each characteristic will be described.

Characteristic (1): MFR 230 ° C., 21.1 according to JIS-K6921 of propylene / α-olefin random copolymer used in the present invention.
Melt flow rate (MFR) at 8N is 10-20
00 g / 10 minutes, preferably 15 to 1500 g /
10 minutes, more preferably 20 to 1000 g / 10
Minutes. If the MFR is less than 10 g / 10 minutes, the spinning pressure will be too high, and it will be difficult to draw at a high draw ratio, resulting in problems such as nonuniform fiber diameter. On the other hand, 2000g / 10
If the amount exceeds the limit, the molecular chain is short, which causes a problem that the strength of the nonwoven fabric becomes low. In order to control the MFR of the polymer, for example, there is a method of appropriately adjusting the polymerization temperature, the amount of catalyst, the supply amount of hydrogen as a molecular weight modifier, or a method of adjusting by adding a peroxide after the completion of the polymerization.

Characteristic (2): Q value Gel permeation chromatography (G) of the propylene / α-olefin random copolymer used in the present invention.
The Q value represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined by
It is 1.5 to 4.0, preferably 1.8 to 3.7, and more preferably 2.0 to 3.5. Q value is 4.
When it exceeds 0, there is a problem that the spin drawability is impaired due to the presence of a high molecular weight. On the other hand, if it is less than 1.5, it is difficult to produce even the metallocene catalyst system at present. Q of propylene / α-olefin random copolymer
The value can be adjusted by polymerizing using a catalyst system in which two or more metallocene catalyst components are used in combination or a catalyst system in which two or more metallocene complexes are used in combination, or by performing two or more multistage polymerization at the time of polymerization. The Q value can be widely controlled. On the contrary, to adjust the Q value narrowly, propylene / α
After the olefin random copolymer is polymerized, it can be adjusted by melt kneading using an organic peroxide.

The Q value is measured under the following conditions. Device: Waters HLC / GPC 150
C column temperature: 135 ° C. solvent: o-dichlorobenzene flow rate: 1.0 ml / min column: Tohso Corp. GMH _HR- H (S)
HT 60 cm × 1 Injection amount: 0.15 ml (without filtration) Solution concentration: 5 mg / 3.4 ml Sample preparation: 5 mg / using o-dichlorobenzene
Adjust to 3.4 ml of solution and dissolve at 140 ° C. for 1-3 hours. Calibration curve: A polystyrene standard sample is used. Calibration curve order: Primary PP molecular weight: PS x 0.639

Characteristic (3): T ₈₀ -T ₂₀ (Temperature difference of elution amount by TREF) The propylene / α-olefin random copolymer used in the present invention has a temperature rising elution fractionation (TREF: Temper).
ature Rising Elution Fract
80) in the integrated elution curve obtained by
The difference in temperature between 20 wt% Temperature _{(T 80)} weight% is eluted elutes _{(T 20),} the T 80 _{-T 2 0,} and at 10 ° C. or less, preferably 2 to 9 ° C., more preferably Is 2
~ 8 ° C. When T ₈₀ -T ₂₀ exceeds 10 ° C, low-temperature elution components increase, which causes problems such as stickiness of constituent fibers, deterioration of surface slip characteristics when formed into a nonwoven fabric, and deterioration of spinning performance. In addition, since a large amount of ethylene introduced as a copolymer is taken into the low temperature elution component, such a component causes discoloration or odor after irradiation with radiation. The T ₈₀ -T ₂₀ of the polymer being within the specific narrow range as described above means that the molecular weight distribution of the polymer is more uniform.

Here, the temperature rising elution fractionation (TRE
F) means that the polymer is completely dissolved in the presence of an inert carrier at a constant high temperature and then cooled to form a thin polymer layer on the surface of the inert carrier, and then the temperature is continuously or gradually increased. This is a method in which the temperature is raised, the eluted components are recovered, the concentration thereof is continuously detected, and the composition distribution of the polymer is measured by a graph (integrated elution curve) drawn by the elution amount and the elution temperature. For more information on elevated temperature elution fractionation (TREF) measurements, see Journal of Appl.
ied Polymer Science Vol. 26, pp. 4217-4231 (1981), and the present invention is also carried out accordingly.

Specifically, the measurement is performed under the following conditions.
The measuring device is CFC T-10 made by Dia Instruments.
First, the sample to be measured is used as a solvent (o-
It is dissolved at 140 ° C. using dichlorobenzene) so that the concentration becomes 3 mg / ml, and this is injected into the sample loop in the measuring device. The following measurements are automatically performed according to the set conditions. The sample solution held in the sample loop is separated by utilizing the difference in melting temperature. TREF column (inner diameter 4 filled with glass beads as an inert carrier)
mm, length 150 mm, stainless steel column attached to the device). Next, the sample is 1 ° C /
Allow to cool to a temperature of 140 ° C. to 0 ° C. at a rate of minutes. T
After holding the REF column at 0 ° C for another 30 minutes,
2 ml of the component dissolved at the temperature of 1 to SEC column (Showa Denko AD80) at a flow rate of 1 ml / min.
6MS (3 tubes). While the molecular size is being fractionated by SEC, the temperature is raised to the next elution temperature (10 ° C.) in the TREF column and the temperature is maintained for about 30 minutes. The measurement of each elution section by SEC is performed at intervals of 39 minutes. The elution temperature is from 0 ℃ to 40 ℃ every 10 ℃, 40 ℃
To 90 ° C in 5 ° C increments, from 90 ° C to 140 ° C in 4 ° C
The temperature is raised stepwise at every ° C. The solution separated by the molecular size in the SEC column is detected by an infrared spectrophotometer attached to the apparatus, and a chromatograph in each elution temperature section can be obtained. The infrared spectrophotometer performs detection using the absorbance at a detection wave number of 3.42 μm, and the following data processing is performed assuming that the amount of the polymer component in the solution is proportional to the absorbance. The chromatogram in each elution temperature segment is processed by the built-in data processing software, and the elution amount in each elution temperature segment is calculated based on the area of each chromatogram so that the integration is 100%. Furthermore, from the elution amount of each elution temperature category obtained,
An integrated elution curve is created. The 0 ° C-soluble content indicates the amount (%) of the polymer component eluted at 0 ° C.
₂₀ is a temperature at which the cumulative elution amount is 20%, and T ₈₀ is a temperature at which the cumulative elution amount is 80%.

Characteristic (4): 0 ° C soluble content in TREF measurement; 0 ° C soluble content in TREF measurement of the propylene / α-olefin random copolymer used in the present invention is 3
The content is preferably not more than 1.0% by weight, more preferably not more than 1.0% by weight, further preferably not more than 0.5% by weight, particularly preferably not more than 0.3% by weight. 0 ℃ at TREF measurement
If the soluble content exceeds 3% by weight, it may cause discoloration or odor after irradiation with radiation, which is not preferable. Propylene / α-
The amount of the TREF 0 ° C soluble component of the olefin random copolymer is such that, when the metallocene catalyst component is loaded on the carrier and the polymerization is carried out by using a catalyst whose loading is non-uniform, the low molecular weight increases, and accordingly TREF 0 ° C. The amount of soluble matter increases. Therefore, the amount of the TREF soluble component at 0 ° C. can be adjusted to 3% by weight or less by polymerizing using a catalyst in which the metallocene catalyst component is uniformly supported on the carrier.

Characteristic (5): α-olefin content The content of α-olefin (comonomer) in the propylene / α-olefin random copolymer used in the present invention is 1
-18 mol%, preferably 2.5-10 mol%, more preferably 3-8 mol%. Particularly when the comonomer is ethylene, 1 to 12 mol% is preferable.
When the comonomer content is less than 1 mol%, the mechanical properties after irradiation with radiation (reduction in nonwoven fabric strength) are remarkable. On the other hand, if it exceeds 18 mol%, solidification during spinning is slowed, productivity is impaired, and the strength and rigidity of the nonwoven fabric are significantly reduced. The α-olefin content in the polymer can be easily adjusted by controlling the amount of α-olefin supplied to the polymerization reaction system.
In the present invention, the α-olefin content is quantified by a Fourier transform infrared spectrophotometer.

Characteristic (6): Melting peak temperature (Tm) The Tm of the propylene / α-olefin random copolymer used in the present invention represents the peak temperature of the melting curve obtained by a differential scanning calorimeter (DSC), 110 ~ 140 ° C
Is. If the Tm exceeds 140 ° C., the opportunity characteristics (irradiation strength of the non-woven fabric) after irradiation with radiation are significantly reduced. On the other hand, 1
When the temperature is lower than 10 ° C, solidification during spinning is slowed, productivity is impaired, and non-woven fabric strength and rigidity are significantly reduced. The melting peak temperature (Tm) was measured by a differential scanning calorimeter (DS) manufactured by Perkin Elmer Co.
Using C), take a sample amount of 10 mg,
After being held for 40 minutes, the peak position of the curve drawn when crystallizing to a temperature of 40 ° C. at a temperature lowering rate of 10 ° C./min and then melting at a temperature rising rate of 10 ° C./min is the melting peak temperature Tm.
(° C).

Further, in the propylene / α-olefin random copolymer of the present invention, various additives such as a heat resistance stabilizer, an antioxidant, a weather resistance stabilizer, and an ultraviolet ray are added to the extent that the object of the present invention is not impaired. An absorber, a crystal nucleating agent, a copper damage inhibitor, an antistatic agent, a slip agent, an anti-blocking agent, an antifogging agent, a colorant, a filler, an elastomer, a petroleum resin and the like can be added.

The fibrous non-woven fabric molding material in the present invention comprises the above-mentioned propylene / α-olefin random copolymer and, if necessary, the above-mentioned various additives and other resin components in a dry blend state or a melt kneader. Using,
It is preferably melt-kneaded by heating at 180 to 300 ° C. and provided in the form of pellets cut into particles.

The polypropylene-based non-woven fabric of the present invention is as described above.
Fiber non-woven fabric molding materials, spun bond method, melt blow
Or directly fibrillate the water and then entangle it with water.
It is manufactured by a molding method such as a molding method or a card method. The non-woven fabric
The basis weight is 5 to 200 g / m ^TwoIs preferred.
Also, non-woven fabrics can be used not only in single layers, but
Non-woven fabric obtained by the Bond Bond method and obtained by the melt blown method
Laminated nonwoven fabric or product of nonwoven fabric and film
It can also be suitably used as a layered body.

When molding the nonwoven fabric, the constituent fibers may be single fibers, core-sheath type composite fibers, or side-by-side type composite fibers. In the case of composite fibers, the above-mentioned propylene / α-olefin random copolymer is used. Should be contained as one component of the composite fiber.

The medical polypropylene non-woven fabric of the present invention has an electron beam irradiation condition of a voltage of 4.8 MeV and a current of 20 m.
A, the strength retention of the nonwoven fabric that has been subjected to electron beam irradiation with a dose of 40 KGy is preferably 70% or more before and after electron beam irradiation. The nonwoven fabric strength retention rate after electron beam irradiation is preferably 80% or more, and more preferably 90% or more. If the strength retention rate is less than 70%, there is a problem in use as a medical non-woven fabric due to insufficient strength and the like. The irradiation of radiation uses an electron beam as an actinic ray, and 200 mm x 300
An electron irradiation device "Dynamitron 5 MeV Electron Accelerator" (manufactured by RDI) was used on one side of the non-woven fabric with a size of mm to output 5.0 Mev 200 kW and a dose of 40 KGy.
It is defined by the irradiation conditions. A U-2000 spectrophotometer manufactured by Hitachi, Ltd. is used as the dose measuring device. The strength of the non-woven fabric irradiated with radiation is lower as the radiation dose is higher, and is lower in γ-ray irradiation than in electron beam irradiation, but in the present invention, it is based on the above-mentioned radiation irradiation conditions. . The strength of the non-woven fabric is JIS L
Measure according to 1096. That is, 50 mm x 300
mm nonwoven fabric is measured under the condition that the chuck distance is 200 mm and the pulling speed is 200 mm / min, and the maximum strength in the displacement-strength curve is taken as the tensile strength of the nonwoven fabric. The strength retention of the nonwoven fabric after electron beam irradiation is calculated by the following formula as to how much tensile strength is retained before and after irradiation with radiation. (Strength retention before and after electron beam irradiation) = (tensile strength after electron beam irradiation) / (tensile strength before electron beam irradiation) × 100 (%)

Here, the radiation irradiation treatment is a treatment used as a sterilization treatment, in which high-energy ionizing rays such as electron beams or γ rays are irradiated, and the irradiation dose is 20 to 20 which is a usual industrial standard. It is in the range of 50 KGy. By irradiation treatment, molded articles and substances contained therein can be effectively sterilized, and are widely used for preventing germination of potatoes and sterilizing medical instruments such as syringes and drip instruments.

The polypropylene-based nonwoven fabric of the present invention produced by the above method has a high strength retention after irradiation with radiation,
It can be used as a medical non-woven material used after radiation sterilization, for example, as a medical instrument, surgical clothes, drapes, surgical sheets, artificial dialysis and blood filtration filters, syringes and drug packaging materials.

[0043]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. The measurement of physical properties is as follows. The propylene used in Examples and Comparative Examples
The method for producing an α-olefin copolymer is shown in Polymerization Examples.

(1) MFR: measured according to JIS-K6921-2 Annex. (Conditions: temperature / 230 ° C, load 21.18N)

(2) Melting peak temperature (Tm): measured by the method described above.

(3) Q value: measured by Waters H
The following polystyrene standard sample was used as a calibration curve using LC / GPC 150C according to the method described in the embodiment of the invention.

[0047]

[Table 1] Calibration curve order: Primary PP molecular weight: PS x 0.639

[0048] According to (4) Temperature rising elution fractionation _{(TREF), T 80 -T 20} , 0 ℃ soluble content: temperature rising elution fractionation (TREF) was measured under the following conditions. As the measuring apparatus, CFC T-102L manufactured by Dia Instruments was used, and the measuring condition was performed according to the method described in the embodiment of the invention.

(5) Tensile strength of non-woven fabric: JIS L10
According to 96, a non-woven fabric of 50 mm × 300 mm was measured under the conditions of a chuck distance of 200 mm and a pulling speed of 200 mm / min, and the maximum strength in the displacement-strength curve was taken as the tensile strength of the non-woven fabric.

(6) Strength retention rate after radiation irradiation: The tensile strength retention rate of the nonwoven fabric before and after radiation irradiation was calculated by the following formula as to how much tensile strength was retained before and after radiation irradiation. (Strength retention rate before and after irradiation of radiation) = (Tensile strength after irradiation of radiation) / (Tensile strength before irradiation of radiation) × 100 (%) In addition, irradiation is performed by electron beam irradiation and γ-ray irradiation. The conditions are shown below. (I) Electron beam irradiation irradiated non-woven fabric piece: 200 mm × 300 mm Electron accelerator: Dynamitron output: voltage 4.8 MeV current 20 mA Sample transfer: cart conveyor speed 13.5 m / min Dose: 20 KGy, 40 KGy 2 levels irradiation direction: one side ( ii) γ-ray irradiation irradiation nonwoven fabric piece: 200 mm × 300 mm Radiation source: Co ⁶⁰ radiation source, 450,000 Ci Irradiation table: Conveyor type automatic irradiation table Dose: 40 KGy

(7) Hue determination: For 10 panelists,
The degree of discoloration of the non-woven fabric before and after irradiation with radiation was evaluated, and the judgment criteria were as follows. ◯: 8 or more people judged not discolored △: 4 to 7 people judged not discolored ×: 3 people or less judged not discolored

(8) Judgment of odor: Ten panelists judged the odor of nonwoven fabric before and after irradiation with radiation, and judged according to the following criteria. ○: 8 or more people judged that there was no problem with odor △: 4 to 7 people judged that there was no problem with odor ×: 3 people or less judged that there was no problem with odor

Polymerization Example 1 (1) Preparation of catalyst A three-necked flask (volume: 1 L) was charged with 20 g of smectite group silicate (Ben clay SL manufactured by Mizusawa Chemical Co., Ltd.) sequentially treated with sulfuric acid and 200 mL of heptane. It was treated with 50 mmol of trinormal octylaluminum and then washed with heptane to obtain a slurry 1. In another flask (volume 200 mL), heptane 90 mL, [(r) -dichloro [1,1'-dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) -4H-azurenyl}]
Zirconium] 0.3 mmol and triisobutylaluminum 1.5 mmol were prepared as a slurry 2. Slurry 2 was added to Slurry 1 and stirred at room temperature for 60 minutes. Thereafter, 210 mL of heptane was added, and this slurry was introduced into a 1 L autoclave. After the internal temperature of the autoclave was set to 40 ° C, propylene was fed at a rate of 10 g / hour to carry out preliminary polymerization while maintaining 40 ° C for 4 hours.
The residual polymerization was carried out for a period of time to obtain 83 g of a preliminary polymerization catalyst.

(2) Production of propylene / α-olefin random copolymer In a reactor having an internal volume of 270 L, liquid propylene, ethylene,
Hydrogen, and triisobutylaluminum (TIBA)
Was continuously fed to maintain the internal temperature at 62 ° C. The supply amount of propylene was 38 kg / hr, the supply amount of ethylene was 1.1 kg / hr, the supply amount of hydrogen was 0.25 g / hr, and the supply amount of TIBA was 18 g / hr. The preliminary polymerization catalyst was slurried with liquid paraffin and fed at 1.1 g / hr. As a result, 11.2 kg / hr of propylene
An ethylene random copolymer I was obtained. The propylene / ethylene random copolymer I thus obtained had MFR = 24.0.
g / 10 minutes, ethylene content = 5.0 mol%, Tm = 1
It was 25.9 ° C. and the Q value was 2.7.

Polymerization Example 2 Using the solid catalyst prepared in Polymerization Example 1, the hydrogen supply rate was changed to 0.36 g / hr, and the feed rate of the prepolymerization catalyst made into a slurry with liquid paraffin was changed to 0.87 g / hr. Polymerization was performed in the same manner as in Polymerization Example 1 except for the above. As a result, 12.1 kg / hr of propylene / ethylene random copolymer II was obtained. The obtained propylene / ethylene random copolymer II has MFR = 44.0 g / 10
Min, ethylene content = 5.0 mol%, Tm = 125.2
C., Q value = 2.8.

With respect to 100 parts by weight of this propylene / ethylene random copolymer II powder, 0.1 parts of a master batch of 3-methylbutene polymer as a crystal nucleating agent was added.
0 parts by weight, 1,3,5-tris [(4
-Tert-butyl-3-hydroxy-2,6-xylyl) methyl] -1,3,5-triazine-2,4,6
0.04 parts by weight of (1H, 3H, 5H) -trione (manufactured by Cytec, trade name Sianox 1790), tris- (2,4-di-t-butylphenyl) phosphite (manufactured by Ciba Specialty Chemicals, 0.05 part by weight of Irgaphos 168), calcium stearate as a neutralizing agent (Nitto Kasei Kogyo, trade name Ca-St)
0.05 part by weight, and a peroxide (Perhexa 25B:
(Nippon Yushi Co., Ltd.) was blended at 4000 ppm and mixed at a high speed with a Henschel mixer at 500 rpm for 3 minutes.
mm single screw extruder (manufactured by Union Plastics Co., Ltd.) was used to melt, knead, cool and cut at an extrusion temperature of 230 ° C. to prepare a pellet-shaped propylene copolymer composition II ^* . The obtained propylene / ethylene random copolymer composition II ^* had MFR = 1000 g / 10 minutes, ethylene content = 5.0 mol%, Tm = 125.2 ° C., and Q.
The value was 1.7.

Polymerization Example 3 Using the solid catalyst prepared in Polymerization Example 1, ethylene was supplied in an amount of 1.6 kg / hr and hydrogen was supplied in an amount of 0.33 g / h.
r, except that the feed amount in which the prepolymerization catalyst was slurried with liquid paraffin was changed to 0.76 g / hr,
Polymerization was carried out in the same manner as Polymerization Example 1. As a result, 12.
6 kg / hr propylene / ethylene random copolymerization I
II was obtained. The obtained propylene / ethylene random copolymer III has MFR = 24.0 g / 10 minutes, ethylene content = 6.2 mol%, Tm = 120.3 ° C., and Q value =
It was 2.8.

Polymerization Example 4 Using the solid catalyst prepared in Polymerization Example 1, the hydrogen supply amount was changed to 0.03 g / hr, and the feed amount of the preliminary polymerization catalyst made into a slurry with liquid paraffin was changed to 1.5 g / hr. Polymerization was performed in the same manner as in Polymerization Example 1 except for the above. As a result, 12.5 kg / hr of propylene / ethylene random copolymer IV was obtained. The obtained propylene / ethylene random copolymer IV has an MFR of 6.0 g / 10 minutes, an ethylene content of 5.0 mol%, a Tm of 125.4 ° C., and a Q of
The value was 2.7.

Polymerization Example 5 After thoroughly replacing a stirring autoclave having an internal volume of 200 liters with propylene, 60 L of n-heptane dehydrated and deoxygenated was introduced, and 16 g of diethylaluminum chloride and a titanium trichloride catalyst (M.・ M company
4.1 g were introduced at 50 ° C. under a propylene atmosphere. Further, while maintaining the gas phase hydrogen concentration at 6.0% by volume, at a temperature of 50 ° C., 5.7 kg of propylene and 0.2 of ethylene.
After feeding for 4 hours at a rate of 8 kg / hour, the polymerization was continued for another hour. As a result, 12 kg of propylene / ethylene random copolymer V was obtained. The resulting propylene / ethylene random copolymer V had an MFR of 6.4 g /
10 minutes, ethylene content = 5.9 mol%, Tm = 140
C., Q value = 4.4.

Polymerization Example 6 Random copolymerization of propylene and ethylene was carried out in the same manner as in Polymerization Example 5 except that the amount of ethylene supplied was 0.35 g / hr. As a result, 20kg / hr
A propylene / ethylene random copolymer VI was obtained.
Obtained propylene / ethylene random copolymer VI
Has MFR = 6.0 g / 10 min, ethylene content = 6.5
It was mol%, Tm = 130 ° C., and Q value = 4.5.

[0061] Using the propylene-ethylene random copolymer V, VI, peroxides: except for using 4000ppm the amount of (PERHEXA 25B, manufactured by NOF Corporation), similar to the polymer composition II ^* adjustment method Then, polymer compositions V ^* and VI ^* were obtained. The obtained propylene / ethylene random copolymer composition V ^* had MFR = 25 g / 10.
Min, ethylene content = 5.9 mol%, Tm = 140 ° C.,
The Q value was 3.8. The propylene / ethylene random copolymer composition VI ^* thus obtained had an MFR of 25 g / 1.
0 minutes, ethylene content = 6.5 mol%, Tm = 130
C., Q value = 3.8.

Table 2 shows the physical properties of the propylene / ethylene random copolymers I to V produced in the above Polymerization Examples 1 to 6. As is apparent from Table 2, the polymers I to III are the propylene / ethylene random copolymers of the present invention having the characteristics (1) to (6), and the polymers IV to VI and the polymer composition II ^* , IV ^{* to} VI ^* are copolymers outside the present invention.

[0063]

[Table 2]

Examples 1 to 3 To 100 parts by weight of the powder of the polymers I to III shown in Table 2
On the other hand, as a crystal nucleating agent, 3-methylbutene polymer
0.10 parts by weight of star batch, 1 as an antioxidant,
3,5-Tris [(4-tert-butyl-3-hydro
Xy-2,6-xylyl) methyl] -1,3,5-tri
Azin-2,4,6 (1H, 3H, 5H) -trione
(Made by Cytec, product name Cyanox 1790)
0.04 parts by weight, tris- (2,4-di-t-butylphene)
Phenyl) Phosphite (Ciba Specialty Chemica)
Made by Ruze, brand name Irgaphos 168) 0.05 parts by weight,
And calcium stearate as a neutralizer (Nitto Kasei
0.05 parts by weight of trade name, Ca-St)
Mixed at 500 rpm for 3 minutes with a shell mixer
After that, φ50mm single screw extruder (Union Plastics Co., Ltd.
Manufactured by Mfg. Co., Ltd.), melting, kneading,
Cooled, cut and pelletized propylene copolymer composition
The thing was prepared. Next, using the obtained composition as a raw material,
Melt spinning was performed using a spinneret with 24 reels. Melting
Spinning is performed at a spinning temperature of 230 ° C. and a discharge rate of 0.8 g / min / hole.
And then stretched with air soccer, fineness 2 decitec
A single fiber of susu was obtained. This single fiber down the air football
After accumulating on the conveyor in, set to 110 ℃
The fibers are fused together by an embossing roll, and the basis weight is 40
g / m ^TwoA non-woven fabric was obtained. Then radiate to the resulting nonwoven
Irradiate a line to judge the hue and odor, and before and after irradiation
Was measured to determine the strength retention rate. The results are shown in Table 3.
Shown in.

Example 4 A polymer composition II ^* was used as a raw material and a melt blown method was used. The fineness was 0.3 decitex and the basis weight was 40 g / m.
A nonwoven fabric of ² was obtained. The obtained nonwoven fabric was irradiated with the same radiation as in Example 1 to judge the hue and odor, and the strength before and after irradiation was measured to obtain the strength retention rate. The results are shown in Table 3. The conditions of the melt blown method are as follows.

Die: Die size 20 inches, 720 nozzle holes, nozzle diameter 0.3 mm Spinning conditions: Spinning temperature 270 ° C., Air temperature 250 ° C., Air flow rate 70 Nm
³ / hr Fiber collection condition: Ejector-conveyor distance 200 m
m, conveyor speed 3.2 m / min

Example 5 The polymer I composition prepared in Example 1 was used as the first component (sheath component), and homopolypropylene (SA05; manufactured by Nippon Polychem) was used as the second component (core component). Melt spinning was performed using a core-sheath type spinneret having 24 holes so that the sheath ratio was 1/1. Melt spinning is spinning temperature 2
It was carried out at 30 ° C., a discharge rate of 0.8 g / min / hole, and then stretched by air sucker to obtain a core-sheath type composite fiber having a fineness of 2 decitex. After the fibers were collected on a conveyor below the air sucker, the fibers were fused with an embossing roll set at 110 ° C. to obtain a nonwoven fabric having a basis weight of 40 g / m ² . The obtained nonwoven fabric was irradiated with the same radiation as in Example 1 to judge the hue and odor, and the strength before and after irradiation was measured to obtain the strength retention rate. The results are shown in Table 3.

Comparative Example 1 Homopolypropylene (SA05 (manufactured by Nippon Polychem)) was used as a polymer, and the embossing roll temperature was 140 ° C.
A nonwoven fabric was produced in the same manner as in Example 1 except that the above was adopted. The obtained nonwoven fabric was irradiated with the same radiation as in Example 1 to judge the hue and odor, and the strength before and after irradiation was measured to obtain the strength retention rate. The results are shown in Table 3.

Comparative Examples 2 to 3 To the polymers V and VI, 300 ppm of peroxide (Perhexa 25B: manufactured by NOF CORPORATION) was added, and the final MFR was 2 respectively.
A nonwoven fabric was obtained in the same manner as in Example 1 except that the polymer prepared so as to have a rate of 5 g / 10 minutes was used. However, in Comparative Example 3, the embossing roll temperature was 120 ° C. The obtained nonwoven fabric was irradiated with the same radiation as in Example 1 to judge the hue and odor, and the strength before and after irradiation was measured to obtain the strength retention rate. The results are shown in Table 3.

Comparative Example 4 To SA05 (manufactured by Nippon Polychem), 3000 ppm of peroxide (Perhexa 25B: manufactured by NOF CORPORATION) was added, and the final M
A nonwoven fabric having a fineness of 0.3 decitex and a basis weight of 40 g / m ² was obtained in the same manner as in Example 4, except that the polymer prepared so that the FR was 800 g / 10 min was used. The obtained nonwoven fabric was irradiated with the same radiation as in Example 1 to judge the hue and odor, and the strength before and after irradiation was measured to obtain the strength retention rate. The results are shown in Table 3.

Comparative Example 5 Melt spinning was performed in the same manner as in Example 1 except that the powder of the polymer IV was used, but the stretch followability in air sucker was very poor, and many stretch breaks occurred. Couldn't get

[0072]

[Table 3]

As is clear from Table 3, according to each of the above-mentioned examples, a polypropylene resin nonwoven fabric excellent in radiation resistance can be obtained. On the other hand, the non-woven fabric using homopolypropylene has a lower strength retention rate and a worse hue and odor upon irradiation with radiation (Comparative Examples 1 and 4). Q
The non-woven fabric using the polymer whose value, T ₈₀ -T ₂₀ , and 0 ° C. soluble content are out of the range is deteriorated in hue and odor by irradiation with radiation (Comparative Examples 2 and 3).

[0074]

EFFECT OF THE INVENTION Since the polypropylene-based nonwoven fabric of the present invention uses a specific propylene / α-olefin random copolymer, it has little deterioration in mechanical properties due to radiation irradiation, and has little stickiness, discoloration or odor for medical use. It is a polypropylene-based non-woven fabric and can be suitably used as a medical non-woven fabric such as surgical clothes, drapes, artificial dialysis and blood filtration filters, and syringes and drug packaging.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) D01F 8/06 D01F 8/06 (72) Inventor Junichi Nishimura 3-1, Chidori-cho, Kawasaki-ku, Kanagawa Prefecture Nihon Polychem Co., Ltd. Material Development Center F-term (reference) BA05 BA09 BA21 BD04 BD07 BD11 CA38 CA42 DD01 DD15 4L047 AA14 AA27 AB02 AB10 BA04 BA08 CB01 CB10 CC03 CC12 DA00

Claims (7)

[Claims] 1. A medical polypropylene-based non-woven fabric comprising fibers which are polymerized by a metallocene catalyst and have at least one component of a propylene / α-olefin random copolymer having the following properties (1) to (5). Characteristic (1): MFR is 10 to 2000 g / 10 minutes Characteristic (2): Q value is 1.5 to 4.0 Characteristic (3): T ₈₀ -T ₂₀ is 10 ° C. or less Characteristic (4): In TREF measurement 0 ° C soluble content is 3% by weight or less Characteristic (5): α-olefin content is 1 to 18 mol% Characteristic (6): Tm is 110 to 140 ° C (however, MFR is 230 ° C according to JIS-K6921,
The melt flow rate at 21.18 N and the Q value are the ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mw measured by GPC, and T ₈₀ is the temperature rising elution fractionation (TR
In the integrated elution curve obtained by EF), the temperature at which 80% by weight is eluted, T ₂₀ is the temperature at which 20% by weight is eluted, and Tm is the peak temperature of the melting curve obtained by a differential scanning calorimeter (DSC). ) 2. Property (3): T ₈₀ -T ₂₀ is 2 to 8 ° C.
The polypropylene non-woven fabric for medical use according to claim 1, wherein 3. The medical polypropylene according to claim 1, wherein the α-olefin of the propylene / α-olefin random copolymer is ethylene, and the content thereof is 1 to 12 mol%. System non-woven fabric. 4. The fiber containing at least one component of a propylene / α-olefin random copolymer as a single fiber, a core-sheath type composite fiber, or a side-by-side type composite fiber. The polypropylene non-woven fabric for medical use according to any one of items. 5. A sheet-shaped non-woven fabric comprising a fiber containing a propylene / α-olefin random copolymer as at least one component, which is produced by any one of the spunbond method, meltblown method, hydroentanglement method and card method. The medical polypropylene-based nonwoven fabric according to any one of claims 1 to 4, which is a nonwoven fabric. 6. The electron beam irradiation condition is a voltage of 4.8 MeV,
The polypropylene for medical use according to any one of claims 1 to 5, wherein the nonwoven fabric subjected to electron beam irradiation with a current of 20 mA and a dose of 40 KGy has a strength retention of 70% or more before and after electron beam irradiation. Medical non-woven fabric using a non-woven fabric. 7. A medical polypropylene-based nonwoven fabric obtained by subjecting the medical polypropylene-based nonwoven fabric according to any one of claims 1 to 6 to radiation treatment.