JPH11206556A - Fluororesin curtain material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluororesin curtain material suitably used in a work space requiring an undusty (clean) environment to a high degree such as a computer room and an IC manufacturing factory. SOLUTION: A fluororesin sheet is composed of an independent polymer containing at least one or more kinds of fluorine containing monomers or a blend with the other polymer, and has the fluorine content not less than 55 wt.% and a melting point of 60 to 220 deg.C. In this case, transmissivity of a beam of light is not less than 80%, and a tensile elastic modulus (at a measured temperature of 23 deg.C) falls within a range of (3×10<7> to 6×10<8> Pa).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material which can be used as various curtains,
The present invention relates to a curtain material using a fluororesin sheet, which is preferably used in a work space (hereinafter, referred to as a "clean room") requiring a highly dust-free (clean) environment, such as an IC manufacturing factory, and more specifically, is transparent. The present invention relates to a fluororesin-based curtain material having excellent heat resistance, flame retardancy, flexibility and secondary workability, and furthermore, excellent contamination prevention properties.

[0002]

2. Description of the Related Art A soft polyvinyl chloride sheet (hereinafter referred to as a "PVC sheet") formed by adding additives such as a plasticizer and a stabilizer to a polyvinyl chloride resin has good moldability, is flexible, and can be used. Because of its simplicity, it is widely used from agricultural houses, industrial materials, building materials to household goods.
Here, a curtain is used in the clean room or the like for the purpose of partitioning a work space, and a PVC sheet has been used as a material for the curtain. However, in the PVC sheet, a plasticizer and an additive such as a stabilizer are used. There are problems such as contamination due to volatilization and deterioration in transparency.

[0003] In other words, the additives generally contained in the PVC sheet are not sufficiently soluble and dispersible in the polyvinyl chloride resin, and partially ooze out to the surface to impair the transparency or to pass through other substances or humans. Or, it becomes vapor and evaporates into the air, so that it adheres to electronic devices and members in a clean room or the like, which is one of the causes of deterioration in function due to contamination.

Further, polyvinyl chloride resin is a material having relatively low chemical stability, and is liable to cause a dehydrochlorination reaction by heat or light, and as a result, the PVC sheet is colored and the transparency is impaired. Become. Even inside a room such as a clean room, the stimulus such as heat or light cannot be completely eliminated, so that this reaction proceeds and deterioration cannot be suppressed substantially.

[0005] Therefore, there is a strong demand for a material that can substitute for such a PVC sheet. However, in addition to the qualities naturally required as curtain functions such as transparency, flame retardancy and flexibility, there is also a need for static electricity of electronic equipment. Many features such as antistatic processing to eliminate malfunctions and adhesion of dust and dirt, and secondary workability such as splicing to expand the size according to the work space, and pollution prevention. No suitable curtain material that can simultaneously satisfy the above requirements has been found.

[0006]

DISCLOSURE OF THE INVENTION The present invention has found a fluororesin curtain material which can solve the above-mentioned problems. The gist of the present invention is that a polymer containing at least one kind of fluorine-containing monomer is used alone. Alternatively, it consists of a blend with another polymer and has a fluorine content of 55
It is a fluororesin sheet having a melting point of 60 to 220 ° C and a light transmittance of 80% or more and a tensile modulus (measuring temperature of 23 ° C) of 3 × 10 ^{7 to} 6 × 10 ⁸ Pa. It is in fluororesin curtain material.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The fluororesin-based curtain material in the present invention is a fluororesin sheet made of a polymer containing at least one kind of fluorine-containing monomer alone or a blend with another polymer, and the fluorine-containing monomer component is vinyl fluoride. , Vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, pentafluoropropylene, hexafluoropropylene and the like, and a homopolymer or copolymer of a fluorine-containing monomer, or the fluorine-containing monomer, ethylene, alkyl vinyl ether and the like It is composed of a copolymer in which a vinyl monomer or the like is used in combination, or a blend thereof.

[0008] Any material can be used as long as it can be formed into a sheet, that is, a material that can be hot-melt-molded. Fluororesins other than tetrafluoroethylene homopolymer (PTFE) can be used without any particular limitation.

Specifically, a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer,
Examples thereof include a tetrafluoroethylene-vinylidene fluoride-hexafluoropropylene copolymer and polyvinylidene fluoride.

The fluororesin sheet having the above composition has a fluorine content of 55% by weight or more and a melting point of 60 to 220%.
° C, and the fluorine content is 55%.
If the amount is less than the weight percentage, there is a problem that the flame retardancy of the curtain material is impaired.

When the melting point is less than 60 ° C., the heat resistance at the time of secondary processing such as seaming is insufficient, and particularly, softening becomes remarkable in the summer and blocking occurs.
There is a problem that handling becomes difficult. Usually, a heat sealing method is often used for joining the curtain material, and it is necessary to press the curtain material at a temperature equal to or higher than the melting point at the time of heel sealing.
It is preferable that the temperature is not higher than ° C. The melting point in the above range can be adjusted by adjusting the monomer component ratio, crystallinity, and the like of the resin used.

Further, the fluororesin curtain material of the present invention needs to have a light transmittance of 80% or more and a tensile modulus in a specific range. By setting the light transmittance to 80% or more, the transparency is not impaired when processed into a curtain. It is essential that the curtain has a high degree of flexibility due to its use, and as a minimum condition, the tensile modulus at a measurement temperature of 23 ° C. must be 3 × 10 ^{7 to} 6 × 10 ⁸ Pa.

Setting the measurement temperature in the range of 23 ° C. corresponds to a normal ambient temperature. The method for measuring the tensile elastic modulus is a method in which dynamic viscoelasticity is measured by a tensile method at a cycle of 1 Hz to determine a storage elastic modulus. In order to make the above range of the tensile modulus, the monomer component ratio of the resin used in the same manner as the adjustment of the melting point,
It is possible by adjusting the crystallinity and the like.

When the fluororesin-based curtain material of the present invention is used as a curtain material for a clean room or the like, it needs to have an appropriate flexibility as a curtain, that is, a so-called good drape property. The product of the thickness of the material is 5 × 10 ³ -1 × 10
Good drapability can be obtained if it is in the range of ⁵ (N / m). If the product of the tensile modulus and the thickness is less than 5 × 10 ³ (N / m), the stiffness of the curtain material is too weak to form drape,
On the other hand, if it exceeds 1 × 10 ⁵ (N / m), the drape of the curtain material is hardly obtained because the curtain material is too strong.

Further, the plastic sheet is generally an insulator and therefore easily generates static electricity. Particularly in a clean room, the plastic sheet is usually kept at a constant temperature (20 to 25 ° C.) and low humidity (relative humidity: 40 to 60%). Therefore, the environment is likely to generate static electricity.

The generation of static electricity in a clean room is a factor in maintaining and managing the cleanliness of sucking and releasing fine dust and dust, and in a clean room handling electronic components such as ICs, static electricity damage of electronic components is caused. Disliked in quality control as promoting the danger of Therefore, it is essential that a curtain for a clean room be subjected to an antistatic treatment.

As a method of the antistatic treatment, (1)
A method in which an opaque conductive material mainly composed of carbon black is printed on the entire surface of the sheet in a pattern such as a tortoise shell. (2) A method of kneading a transparent conductive material into a sheet. (3) A method of coating a transparent conductive material on the entire surface of a sheet is common.

Although each method has advantages and disadvantages,
In the conductive material printing type (1), the entire curtain is difficult to see, and there is a psychological problem in appearance depending on the print pattern.
The type of kneading conductive material (2) is inferior in cost and moldability as compared with a method in which only the surface layer of the curtain is made conductive, so that the amount of conductive material added is limited, and the conductivity tends to be poor. Further, the conductive material coated type (3) has a problem that the conductive material is easily peeled off and it is difficult to maintain the conductivity.

The fluororesin curtain material of the present invention has a feature that it is difficult to adhere to other materials and has excellent anti-staining properties. On the other hand, the method for coating a conductive material in the above (3) uses a conductive material. Therefore, it is indispensable to improve the leakage of the sheet surface because of poor adhesion to the sheet. In the fluororesin-based curtain material of the present invention, it is preferable to adjust the surface tension of at least one surface to a range of 30 to 70 dyne / cm, and if the surface tension is less than 30 dyne / cm, the adhesion of the conductive material is not improved. And 70dyne again
If it exceeds / cm, yellowing of the sheet occurs, and a low molecular weight substance is generated in a large amount on the surface layer of the sheet, whereby the wettability is improved, but the problem that the adhesive strength is reduced is apt to occur.

The fluororesin curtain material having the surface tension adjusted in this way and further coated with a conductive material does not come off and peel off the conductive material, has excellent antistatic properties, flame retardancy, and transparency. In addition, the most suitable curtain for a good clean room can be obtained. As a surface treatment method for imparting a surface tension in the above range, a generally known method may be employed, and examples thereof include a corona treatment method and electron beam irradiation.

As the conductive material to be coated,
Examples include a coating agent mainly containing a conductive polymer such as polypyrrole, polyaniline, polyacetylene, and polythiophene, and a coating agent mainly containing a conductive filler such as tin oxide doped with indium or antimony oxide.

Usually, the fluororesin is formed into a sheet by extrusion using an extruder. Fluororesin itself has excellent extruder flow path in hot melt molding, excellent in mold release properties,
It is a material with high chemical and thermal stability, and can be formed into an extruded sheet by itself. In calendering, since the melt tension is small relative to the peeling force of the molten sheet from the roll, it is necessary to add a considerable amount of an additive such as a lubricant in order to improve the releasability from the roll. This is unfavorable as a method for producing the sheet of the present invention because of the decrease and the deterioration of transparency.

Even when the above-mentioned fluororesin sheet is used as a curtain material, it exhibits a sufficiently good antifouling property as compared with a polyvinyl chloride sheet, but there are also clean rooms which require an extremely high degree of cleanliness. It is not always enough in view of the required quality. This is due to contamination of the fluorocarbon resin with contaminant materials, which may cause residues of catalysts, chain transfer agents, emulsifiers, and other additives and oligomers after polymerization. It is presumed that it was not completely removed in the process and a trace amount remained.

Therefore, as a result of diligent studies, it has been found that a fluororesin curtain material with further improved anti-staining properties can be obtained by adjusting the fluororesin under specific conditions.

Specifically, a fluororesin curtain material is
Volatile components generated by heating at 50 ° C. for 10 minutes were measured by gas chromatography, and the ratio of the weight (g) of the fluororesin-based curtain material to the total peak area in the retention time range of 1 to 50 (minutes) was 1. It has been found that an extremely high degree of cleanliness can be maintained by adjusting the ^{concentration to} 0 × 10 ⁷ (g ⁻¹ ) or less.

The specific measurement conditions are as follows. Apparatus name: GCMS-QP1000EX (manufactured by Shimadzu Corporation) <Volatile conditions> Sample conditions: Weight about 100 mg, heating at 150 ° C x 10 minutes Volatile component expulsion conditions: Expulsion medium He, flow rate 100 l / min Volatile component adsorption conditions : Adsorption medium TENAXTA, temperature -4
0 ° C volatile component desorption conditions: adsorption medium temperature 358 ° C, ejection medium H
e, flow rate 50 ml / min <Gas chromatography conditions> Column conditions: Column type TC-WAX (GL Science Co., Ltd.)
Column size 0.25 mm (inner diameter) × 30 m (length), 0.25 μm (liquid crystal film thickness) Column temperature rise condition 35 ° C (hold for 5 minutes) → (100 ° C /
Min) → 150 ° C. (hold for 5 minutes) Injection conditions: carrier gas He, flow rate 50
ml / min Detection method: TIC method.

1 at 150 ° C. for fluororesin curtain material
The ratio of the weight (g) of the fluororesin-based curtain material to the total peak area in the retention time range of 1 to 50 (minutes) when the volatile component generated by heating for 0 minutes was measured using gas chromatography under the above conditions. is preferably at 1.0 × 10 ⁷ (g ^-1) or less, is not preferable impaired contamination preventive property contamination by volatile components are generated as it exceeds ^{1.0 × 10 7 (g -1)} .

As a method of adjusting the fluororesin curtain material in this range, a method of deaeration from a vent port during melt extrusion in an extruder, a method of deaeration by reheating after sheet formation, and the like are possible. Hereinafter, the present invention will be described with reference to examples.

[0029]

EXAMPLES (Example 1) 30% by weight of vinylidene fluoride,
A fluororesin curtain material in which a fluororesin composed of 50% by weight of tetrafluorotylene and 20% by weight of hexafluoropropylene is extruded into a sheet having a thickness of 100 μm by an extruder, and then corona-treated on both sides of the sheet to adjust the surface tension. I got A transparent acrylic coating material (hereinafter referred to as "transparent conductive material") using tin oxide doped with antimony oxide as a conductive filler on the obtained fluororesin-based curtain material was coated on both sides of the sheet to form a curtain material.

The physical properties of the following items were measured for the fluororesin sheet and the curtain material, and the workability of the curtain was comprehensively evaluated. The results are shown in Table 1. The workability of the curtain was evaluated as (○) when the workability (adhesion) at the time of seaming was good. The appearance was evaluated as (○) when there was no spot on the conductive material coating.

The test evaluation method for each item is as follows. (1) Regarding the light transmittance of the material, the total light transmittance (%) of the fluororesin sheet before coating with the transparent conductive material was measured according to JIS K7105. (2) As for the fluorine content in the raw material, the ratio (% by weight) of the total weight of fluorine atoms to the total weight of fluorine resin constituent atoms was calculated from the monomer component of the fluorine resin. (3) The melting point of the material was measured by a differential scanning calorimetry at a heating rate of 10
C./min, and the endothermic peak temperature was determined. (4) The surface tension of the material was calculated from the contact angle between water and methylene iodide.

(Comparative Example 1) A 3,000-μm-thick sheet was extruded from a fluororesin composed of 30% by weight of vinylidene fluoride, 50% by weight of tetrafluorotylene and 20% by weight of hexafluoropropylene by an extruder.
A corona treatment was applied to both sides of the sheet to obtain a fluororesin curtain material whose surface tension was adjusted.

(Comparative Example 2) Using an ethylene-tetrafluorothylene copolymer, the extruder was used in the same manner as in Example 1 to obtain 20
The sheet was formed into a sheet having a thickness of 0 μm, and then the surface tension was adjusted by corona treatment. A transparent conductive material was coated on both sides of the obtained fluororesin sheet to obtain a curtain material.

Comparative Example 3 A vinylidene fluoride-hexafluoropropylene copolymer was formed into a sheet having a thickness of 300 μm by a calender roll, and then the surface tension was adjusted by corona treatment. A transparent conductive material was coated on both sides of the obtained fluororesin sheet to obtain a curtain material.

Comparative Example 4 A 100 μm thick sheet was extruded from a fluororesin consisting of 30% by weight of vinylidene fluoride, 50% by weight of tetrafluorotylene and 20% by weight of hexafluoropropylene by an extruder in the same manner as in Example 1. Then, a transparent conductive material was coated on both sides of the sheet without any subsequent surface treatment to obtain a curtain material.

[0036]

[Table 1]

From Table 1, it can be seen that the fluororesin-based curtain material of the present invention and Example 1 comprising the curtain using this material are excellent as a curtain for a clean room. On the other hand, in Comparative Example 1 where the tensile elastic modulus of the material × the thickness is too large, the drapability is poor, and in Comparative Example 2 where the melting point of the material is too high, the seamability is inferior. X In Comparative Example 3 in which the value of the thickness was too low, the material was too weak and the drape property was poor. Further, in Comparative Example 4 in which the surface tension was too low, there was a problem that even when the transparent conductive material was coated, spotting or peeling of the conductive material layer occurred.

Next, examples relating to anti-contamination properties will be described. Example 2 Using a copolymerized fluororesin composed of vinylidene fluoride 40 (% by weight), tetrafluoroethylene 40 (% by weight), and hexafluoropropylene 20 (% by weight), a vent port was formed using a bidirectional twin screw extruder. The heating temperature of the cylinder zone is 200 (° C.), the air pressure at the vent port is −60 (cmHg), and the ratio of the cross-sectional area of the vent port passage to the resin flow rate in the cylinder zone having the vent port is 150 (s / m). While performing the degassing treatment under the conditions described above, a fluororesin sheet having a thickness of 100 μm was extruded. When this sheet was measured and evaluated by gas chromatography,
It was 5.3 × 10 ⁶ (g ⁻¹ ), and the contamination prevention property in a clean room was extremely good.

[Evaluation of Pollution Prevention Property] In a clean room (at a constant temperature and humidity control of 23 ° C. and 50% RH) containing 350 or less particles having a size of 0.5 μm or more contained in 1 (m ³ ) air. A PMMA Al vapor deposition plate is placed on the lower surface (the Al vapor deposition surface is up), and a sample sheet of the same size is placed horizontally 10 cm directly above it, and after 5 hours, the PMMA / Al vapor deposition plate is taken out and dropped. The water contact angle of the Al vapor-deposited surface was measured by the method, and the contamination prevention property was determined according to the following criteria.

◎; 56 (°) or more and less than 68 (°) ○; 68 (°) or more and less than 73 (°) Δ; 73 (°) ×; exceeds 73 (°) Incidentally, when no sample is set Was 56 (°), and particularly 73 (°) when an extruded sheet that did not prevent contamination such as degassing was installed.

Example 3 A copolymerized fluororesin composed of vinylidene fluoride 40 (% by weight), tetrafluoroethylene 40 (% by weight) and hexafluoropropylene 20 (% by weight) was 100 μm thick by a single screw extruder. At the same time as extruding the sheet, a polytetrafluoroethylene film was laminated to form a laminated sheet, kept in a hot air oven at 250 ° C. for 3 minutes, then cooled, and the polytetrafluoroethylene film was peeled off to obtain a fluororesin sheet.
When this sheet was measured and evaluated by gas chromatography, it was found to be 8.2 × 10 ⁶ (g ⁻¹ ), and the contamination prevention property in a clean room was also good.

Comparative Example 5 A commercially available vinyl chloride sheet for a clean room curtain (with antistatic treatment) was measured and evaluated by gas chromatography and found to be 2.8 × 10 ⁹ (g ⁻¹ ).
Therefore, the pollution prevention in a clean room was also low.

(Comparative Example 6) A single-screw extruder made of a copolymerized fluororesin consisting of vinylidene fluoride 40 (% by weight), tetrafluoroethylene 40 (% by weight) and hexafluoropropylene 20 (% by weight) without a vent mechanism By the thickness 1
A 00 μm sheet was extruded. When this sheet was measured and evaluated by gas chromatography, it was found to be 2.6 × 10 ⁷
(G ^-1 ), the contamination prevention in a clean room was not sufficient.

[0044]

[Table 2]

From Table 2, it can be seen that Examples 2 and 3 made of the fluororesin curtain material of the present invention have excellent pollution control properties. On the other hand, Comparative Example 5 using a PVC sheet as a base material and Comparative Example 6 having a peak area / weight (g) ratio exceeding 1.0 × 10 ⁷ are inferior in anti-staining properties.

[0046]

As described above, the fluororesin curtain material of the present invention is excellent in transparency, flame retardancy, flexibility, workability of coating and splicing of a conductive material, and furthermore, is excellent in anti-pollution properties, and is a clean room. It is very useful for such applications.

Claims (4)

[Claims] 1. A fluororesin sheet comprising a polymer containing at least one type of fluorine-containing monomer alone or a blend with another polymer, having a fluorine content of 55% by weight or more and a melting point of 60 to 220 ° C. The light transmittance is 80% or more and the tensile modulus (measuring temperature 23 ° C)
Is in the range of 3 × 10 ^{7 to} 6 × 10 ⁸ Pa. 2. The product of tensile modulus and thickness (m) is 5 × 1.
2. The fluororesin-based curtain material according to claim 1, wherein the thickness is in the range of 0 ³ to 1 × 10 ⁵ (N / m). 3. The surface tension of at least one surface is 30.
The fluororesin-based curtain material according to claim 1 or 2, wherein a surface treatment is performed so as to be in a range of from 70 to 70 dyne / cm, or a conductive treatment is further performed on the surface. 4. A volatile component generated by heating at 150 ° C. for 10 minutes is measured by gas chromatography, and the ratio of the weight (g) of the fluororesin curtain material to the total peak area in a retention time of 1 to 50 minutes is measured. 4. The fluororesin-based curtain material according to claim 1, wherein the content is 1.0 × 10 ⁷ (g ⁻¹ ) or less.