JPH02154051A - Nonwoven fabrics - Google Patents

Abstract

PURPOSE:To obtain nonwoven fabric which gives filters which keeps less reduced filtration performance, even after removal of heavy metals and impurities by washing, by using ultrafine fibers of specific polyester. CONSTITUTION:Polyester, preferably polyethylene terephthalate, is melt-spun by the melt blow method and wound up in the form of a network sheet to give a nonwoven fabric of ultrafine fibers in which the average fiber diameter is less than 5mum, preferably less than 2mum, the ratio of the fiber density/ completely amorphous density is less than 1.030, preferably less than 1.025, the apparent crystal size is more than 20Angstrom , preferably 30Angstrom on the 100 face. The nonwoven fabric is washed, preferably extracted with a solvent, to remove heavy metals and impurities whereby a filter suitable for medical purposes is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Production
Regarding 1.

(Prior art) The use of fine denier fibers in medical filters is disclosed in Japanese Patent Application Laid-open No. 54-119012-;
Although disclosed in Japanese Patent No. 013, these methods are applied to fibers having a fiber diameter of 10 μm or less, substantially 4.5 μm or less. For this reason, the separation function is insufficient, and methods using fine denier fibers in the melt blow method and JP-A-60-193488, JP-A-80-20
It is disclosed in Publication No. 3287-F etc. that 3 pra or less is preferable. However, these known studies do not take into consideration the elution of heavy metals used as catalysts contained in +Ve polymers for medical filters and the elution of impurities. In addition, in order to prevent shrinkage and maintain the structure of the non-woven fabric, it is necessary to heat-set it at high temperatures.The shrinkage caused by the heat treatment leads to a low modulus, low compression resistance, and an increase in fiber diameter, resulting in poor filter performance. do.

(Problem to be solved by the invention) Heavy metals and impurities in the polymer, which are the drawbacks of Juto products, can be easily removed with b and θ. Objective [-1] is to provide a nonwoven fabric for filters.

(Steps to Solve the Problem) The present invention makes the fiber M# structure porous to make it easier to remove polymerization metals and impurities in the polymer, and improves the maintenance of m by washing with solvents and heat, and improves the laminated structure. In order to reduce the change, the inventors have discovered that it is effective to reduce shrinkage by crystallization, and have arrived at the present invention.

That is, the present invention provides a nonwoven fabric made of BoJ ester fibers having an average fiber diameter of 5 μm or less, and the ratio of the specific gravity ρ of the polyester fiber to the specific gravity ρa of the complete J1 product (ρ/ρa).
1.030 or less and the apparent crystal size of 100 planes is 20 or more 1-.

The fibers constituting the fibers of the present invention have a uniform diameter of 5 μm or less. The adsorption performance improves as the fiber diameter becomes smaller, so the fiber diameter is preferably smaller than 3μ, more preferably 2.4n++ or less. Fiber diameter is 5
1 or 1 sucks? 1. It is not preferable because the performance is inferior.

The fiber specific gravity ρ constituting the nonwoven fabric of the present invention is completely amorphous specific gravity ρ
The ratio (ρ/ρa) to a is 1.03 or less, preferably 1.
025 or less. If the specific gravity of the fiber becomes high, it becomes difficult to remove metals, which is not preferable. The reason for this is not clear, but wide-angle X-ray diffraction (W A
) Since the specific gravity decreases at the same time as a crystallization pattern is formed, it is speculated that the ratio becomes low due to the generation of microvoids, resulting in a porous structure. Therefore, it is thought that impurities such as polymerization groups and oligomers of the catalyst are easily removed by washing suppression.

100 according to X-ray analysis of the fibers constituting the nonwoven 41 of the present invention
The apparent crystal size (AC5100) is 20
More than 1 person, preferably more than 30 people I-4.

When the crystal size becomes large and impurities are removed, the change in the form of the nonwoven fabric during the removal operation is reduced, and there is no change in the bulky form due to heat swelling during cleaning with 6 L of solvent. If it is not crystallized, it is not preferable because it undergoes significant morphological changes after washing, sterilization, and other treatments.

The shrinkage ratio of the nonwoven fabric of the present invention is preferably 5% or less, more preferably 3% or more. If the shrinkage ratio is high, the change in shape due to heat treatment becomes large, which is not preferable.

The nonwoven fabric of the present invention is made of polyester. Although not particularly limited, examples of preferable polyesters include polyethylene terephthalate and polyethylene terephthalate/iso copolyester.

The weight of the nonwoven fabric of the present invention is usually 20 to 100 g/♂ preferably 40 to 80 g/+I? However, it should not be particularly limited and should be suitable for use.

Obtaining the nonwoven fabric of the present invention - An example is shown below in t%.

Melt blowing is preferable for producing the nonwoven fabric of the present invention.

When using polyethylene terephthalate, the melt viscosity is 1
000 to 1500polse and polymer temperature is 27
It is discharged at a temperature of 5°C to 285°C, and the temperature of the elongated heating fluid is preferably the same, and the ejection speed of the fluid is 0.8 to 1.0%.
Good. The ultra-fine fiber thus spun has a lower ratio -n than that of the fiber P1 which separates from the ultra-fine fiber. The reason for this is not well understood, or it is believed that voids are generated due to ultra-high-speed elongation (for example, the spinning speed in terms of fiber diameter exceeds 20,000 tn/min). It is preferable that the obtained blown fibers be drawn into a net in the form of a net and then subjected to a heat treatment. If the crystal size is as small as 1.5, the crystal size can be increased. In addition, the direction J- of the web strength and the direction J4 of bulkiness due to shrinkage of 1 to 2% are measured. The thus obtained nonwoven fabric of the present invention is preferably used in a medical filter after being washed to remove impurities and harmful substances in the polymer. As the cleaning method, known methods such as solvent extraction, water washing, and hot water washing can be used. The preferred cleaning method is solvent extraction;
This method removes 90 harmful substances and polymers.
% or more. Although the removing operation can be performed by adding l-, the nonwoven fabric of the present invention shows little change in form even if heated fA and cleaning treatment are applied. Therefore, by using the nonwoven 4I of the present invention, it is possible to provide a medical filter with extremely good filter performance.

t, '+;t'l is according to the following) method. .

(b) Observe the nonwoven fabric with a scanning electron microscope, take a photo of it, and then enlarge and print it. Obtained from the formula.

(0) A density gradient tube made of specific gravity 11-hebutane and carbon tetrachloride was prepared, and a sample containing 1.1% of the bubbles was placed in the density gradient tube adjusted to 30°C ± 0.1"C. Convert the sample position in the density gradient tube after standing for a period of time to a specific gravity value from the density gradient tube using a standard glass float. =4
So 4! +1 constant. Read the specific gravity value to four decimal places.

In addition, ρa is 1.3 for polyethylene terephthalate.
33 is used.

(c) Apparent crystal 1t chair with l'oo surface (^C510
0) Wide-angle
,'>,ill [Details are supervised by "X-ray Crystallography" published by Kuotsu 1 Co., Ltd.] G! ! (The crystal size is 1.

The formula of 5herrer is expressed by the following formula.

Apparent amount of crystals is: (0,9λ)/(4B2-α2C
O8O) However, in the IU notation, λ is the wavelength of the X-ray (1,5418
person), B is 11 valence (rad), a is the city angle (G, 9
8xlO""rad)0 reduces the diffraction angle (degrees).

(d) 160°C dry heat shrinkage rate (SHI) 1.1. )
A sheet cut into length and width 20 cva x 20 c was subjected to free treatment in dry heat at 160°C for 30 minutes, and the initial length Q of the length and width. The length Q after treatment is measured and calculated using the following formula. (n = 20) n: 2n (Example) Examples 1 to 4, Comparative Examples 1 to 4 N = limit drying + f o , 5 g of polyethylene terephthalate was spun from a melt blow nozzle with a hole diameter of φ0.15. , fluid pressure, lip temperature, and ejection temperature were changed, the sheet was taken in the form of a sheet, and then heat-treated with a far-infrared heater. Table 1 shows the properties of the sheet obtained.

In addition, the metal content was confirmed by comparison with a standard material using fluorescent X-rays, and a small iI1 analysis was performed after incinerating the sample in a platinum crucible. The UV value is indicated by the 640μ ultraviolet absorption spectrum ratio in the eluate after treatment in water at 130° C. for 60 minutes at a bath ratio of 100. The obtained 7-t was treated at 100° C. for 60 minutes at a water-dioxane 50150 bath ratio of 100, then air-dried, and the heavy metal 3 autofit and UV values were determined at N11l. The results obtained are shown in Table-1. (Air drying was carried out in a clean booth at 20°C.) It can be seen that impurities and heavy metals can be easily removed from the nonwoven fabric of the present invention by washing.

The filter performance was determined by cutting the washed non-woven fabric into 90 mm diameter pieces, stacking 3 sheets in the same direction vertically and horizontally, and measuring 40 mm thick.
,,I+Efficacy diameter 80. It was fixed in the column shown in ■. The column was then treated in washed sterile 21"C steel for 30 minutes and dry exploded for 4 tL.

Using this column, at 25°C, 1μ standard
< tt1% engineering? Renoyon (拉r/)'r 0 for the reason
．． 0.2% surfactant added). The liquid was supplied to the column by a pump controlled to have a pressure of L kg/-, and the liquid passed through the column i [(from 1' for 60 minutes).
The equalization velocity was determined.

Then, in 3M, (1'a l μIII拉r(1(calculated, f) -y m(7) 7 Ilter's capture rate of ?+tf was determined. The obtained results are shown in Table - Shown in 1.

The nonwoven fabric of the present invention had good filtration performance even after passing through the A1 and F stages, while the filtration performance of the nonwoven fabrics outside the present invention was poor after passing through the 6 stages and 1 stage.

Margins below (Effects of the Invention) The nonwoven fabric of the present invention can easily remove 1TI metals and impurities that are undesirable if gold is present in the filter, and there is little deterioration in filter performance due to washing operations.
It is an optimal non-n/I+ for medical filters.

Special 1.1 Applicant Higashi? Tbo Co., Ltd.

Claims (1)

[Scope of Claims] A nonwoven fabric made of polyester fibers having an average fiber diameter of 5 μm or less, where (ρ/ρa)≦1. 030, the apparent crystal size of the 1, 0, and 0 planes is calculated by ACS (10
0) A nonwoven fabric characterized in that it is composed of polyester fibers in which ACS (100)≧20 Å.