JP4576343B2 - Film stretcher - Google Patents

Description

  The present invention relates to a rolling bearing for a tenter clip used in a film stretching apparatus.

An example of a resin stretched film forming apparatus is shown in FIGS. FIG. 4 is a view showing an example of a resin biaxially stretched film manufacturing apparatus. FIG. 5 is a view showing a guide rail of the transverse stretching apparatus of FIG. As shown in FIGS. 4 and 5, the biaxially stretched film manufacturing apparatus includes an extruder 9 for melting and kneading a resin, a die head (T die) 10 for shaping and extruding the melt-kneaded resin to a raw fabric sheet, A longitudinal stretching machine 11 that stretches the anti-sheet in the longitudinal direction, a transverse stretching device 13 that stretches the sheet stretched in the longitudinal direction in the sheet width direction, and a draw that winds the film biaxially stretched in the longitudinal and lateral directions. And a winder 14. The lateral stretching device 13 includes a pair of guide rails 12 that circulate, a plurality of tenter clips 15 that circulate on the guide rails 12 at a predetermined interval, and a means for heating the sheet.
As shown in FIG. 5, the longitudinally stretched sheet is subjected to heat treatment in the lateral stretching apparatus 13 while being heat-treated in a state in which both ends are continuously sandwiched between a plurality of tenter clips 15, and is applied to the widened portions 12 a and 12 b of the guide rail 12. A biaxially stretched film is stretched in the width direction of the sheet along the longitudinal and lateral directions. As shown in FIG. 4, the biaxially stretched film is wound up by a winder 14.

Since the rolling bearing used for the tenter clip 15 is exposed to 200 to 250 ° C. in the transverse stretching apparatus 13 that performs the heat treatment, fluorine grease is enclosed as a lubricant for the rolling bearing for the tenter clip in consideration of heat resistance. It is common.
On the other hand, ester oil is often used for lubricating the guide rail 12. When this ester oil enters the fluorine grease-filled bearing, there is a problem that the fluorine grease leaks from the bearing due to the affinity between the fluorine grease and the metal of the ester oil, and the heat resistance of the bearing decreases. In a tenter clip rolling bearing, a method of using a mixed oil of ester oil and fluorine oil as a base oil is known as a method for preventing leakage of the fluorine grease (see Patent Document 1).
Although the method of using a mixed oil of ester oil and fluorine oil as the base oil is certainly effective as a method of preventing leakage of fluorine grease, it is necessary to properly seal the bearing sealing device, for example, the bearing seal member. For example, it is possible to effectively prevent intrusion of ester oil and leakage of fluorine grease. In this case, a non-contact or light contact seal member made of rubber is suitable as the sealing device, but it is common to use fluoro rubber as the rubber material from the ambient temperature. Conventionally, fluororubber compositions used for such applications include binary copolymers of vinylidene fluoride and hexafluoropropylene (VDF-HFP), and ternary copolymers obtained by adding tetrafluoroethylene to this. A vinylidene fluoride rubber (hereinafter referred to as FKM) such as a polymer (VDF-HFP-TFE) is generally used.

However, since these fluororubber compositions have high polarity and high affinity with ester oils, they may swell depending on the contact state and temperature with the oil. In general, the seal member is made by combining rubber with a metal core, but when the rubber part swells, the non-contact seal member comes into contact with the seal part. There is a problem that the rotational torque of the bearing increases.
In addition, since the stretching apparatus is used at a high temperature, an antioxidant such as an amine compound is generally added to the ester oil in order to prevent oxidative degradation of the ester oil that is the lubricating oil for the guide rail. When amine contacts FKM, there is a problem that a crosslinking reaction occurs at the vinylidene fluoride portion of FKM and the rubber is cured and deteriorated.
JP 2004-301167 A

  The present invention has been made to cope with such a problem, and can suppress deterioration of the seal member even when it contacts with ester oil which is a lubricant for the guide rail, and is reliable and durable at high temperature. An object of the present invention is to provide a rolling bearing for a tenter clip that is excellent in performance.

The film stretching apparatus of the present invention comprises a plurality of tenter clips that move along a guide rail, and the tenter clips are exposed to 200 to 250 ° C. and contain an amine-based additive for running aid ester oil. A rolling bearing that is in contact with the guide rail while being lubricated with the inner ring, an outer ring that is in contact with the guide rail on the outer periphery, a plurality of rolling elements interposed between the inner ring and the outer ring, and one end of the rolling bearing A seal member fixed to the outer ring and having the other end in contact with the inner ring and covering the axially opposite end openings of the inner ring and the outer ring, and is a fluorine grease alone or a mixed oil of fluorine oil and ester oil. Grease comprising oil and a thickener that is a mixture of diurea compound and polytetrafluoroethylene resin powder is enclosed, At least a part of the material that contacts the running assist ester oil on the outside of the bearing and a part of the part that contacts the encapsulated grease consists of a fluororubber molded body, and the fluororubber molded body is made of tetrafluoro A vulcanizable fluororubber composition comprising a copolymer comprising ethylene, propylene, and a crosslinking monomer composed of an unsaturated hydrocarbon having 2 to 4 carbon atoms in which some of the hydrogen atoms are substituted with fluorine atoms moldings der things is, the rubber hardness of the molded article is characterized in that it is a 60 ° to 90 °.

The crosslinking monomer is trifluoroethylene, 3,3,3-trifluoropropene-1, 1,2,3,3,3-pentafluoropropene, 1,1,3,3,3-pentafluoropropylene And at least one monomer selected from 2,3,3,3-tetrafluoropropene.
In addition, the copolymer includes vinylidene fluoride.

In the rolling bearing for tenter clip used in the film stretching apparatus of the present invention, the part of the seal member that contacts the ester oil for lubricating the outer ring is substituted with tetrafluoroethylene, propylene, and a part of hydrogen atoms with fluorine atoms. The seal is made of a fluororubber molded body, which is a molded body of a vulcanizable fluororubber composition comprising a copolymer containing a crosslinked monomer composed of an unsaturated hydrocarbon having 2 to 4 carbon atoms. Even when the member is in contact with ester oil, the volume change due to swelling is small, and an increase in bearing rotational torque can be prevented. In addition, it is possible to effectively prevent foreign substances from entering. Further, even when an amine-based additive is contained in the ester oil, the rubber is hardly deteriorated by curing. As a result, the high temperature durability and oil resistance of the rolling bearing for tenter clip used in the resin film stretching apparatus can be improved.

  A sectional view of an example of a tenter clip in which the rolling bearing for a tenter clip of the present invention is used is shown in FIG. As shown in FIG. 1, the tenter clip 15 includes a grip portion 17 that grips one end 16 of the sheet, and a plurality of tenter clip rolling bearings 18 that allow the tenter clip body 15 a to travel while being guided by the guide rail 12. And are provided. As shown in FIGS. 5 and 1, the tenter clip 15 circulates in the transverse stretching device 13 along the guide rail 12. The longitudinally stretched sheet is gripped at one end 16 of the sheet at the guide rail inlet 12c by the gripping part 17, and is laterally stretched by the guide rail widened parts 12a and 12b by the running of the tenter clip 15 while being heated. This longitudinally and laterally stretched sheet becomes a biaxially stretched film. At the guide rail exit 12d, the gripping portion 17 releases the gripping state, and the tenter clip 15 returns to the entrance of the lateral stretching device 13 along the guide rail 12. The tenter clip rolling bearing 18 is exposed to heat treatment in the transverse stretching device 13 and spraying of ester oil for assisting the running of the tenter clip 15. An amine-based additive is added to the ester oil to prevent oxidative degradation of the ester oil under high temperature conditions in the stretching apparatus, and the outer ring of the bearing 18 and the guide rail 12 are lubricated by the ester oil. Is done.

An example of the tenter clip rolling bearing 18 of the present invention is shown in FIG. FIG. 2 is a cross-sectional view of a deep groove ball bearing.
As shown in FIG. 1, a deep groove ball bearing 1 used as a rolling bearing for a tenter clip has an inner ring 2 having an inner ring rolling surface 2a on the outer circumferential surface and an outer ring 3 having an outer ring rolling surface 3a on the inner circumferential surface. A plurality of rolling elements 4 are arranged between the inner ring rolling surface 2a and the outer ring rolling surface 3a. A grease composition 7 is enclosed at least around the rolling element 4. Esters sprayed as travel aids are provided with retainers 5 for holding a plurality of rolling elements 4 and seal members 6 fixed to the outer ring 3 or the like in the axial end openings 8a and 8b of the inner ring 2 and the outer ring 3, respectively. Prevent oil intrusion and contamination. Here, the seal member 6 is a bridge where at least a portion in contact with the ester oil is composed of tetrafluoroethylene, propylene, and an unsaturated hydrocarbon having 2 to 4 carbon atoms in which a part of hydrogen atoms are substituted with fluorine atoms. The vulcanizable fluororubber composition is made of a copolymer containing a monomer for use.

The seal member 6 may be composed only of a rubber molded body including at least the above-described fluororubber molded body, or may be a composite of a rubber molded body and a metal plate, a plastic plate, a ceramic plate, or the like. From the viewpoint of durability and ease of fixing, a composite of a rubber molded body and a metal plate is preferable.
An example of the sealing member 6 made of a composite of a rubber molded body and a metal plate is shown in FIG. The seal member 6 is obtained by fixing a rubber molded body 6b to a metal plate 6a such as a steel plate. The fixing method may be either mechanical fixing or chemical fixing. As a preferable fixing method, a method of fixing a rubber molded body by laying a metal plate in a vulcanizing mold and performing molding and vulcanization at the same time can be mentioned.

The seal member 6 can be mounted by (1) fixing one end 6c of the seal member 6 to the outer ring 3, and forming the labyrinth gap along the V groove on the seal surface of the inner ring 2 at the other end 6d. One end 6c of the member 6 is fixed to the outer ring 3, and the other end 6d is brought into contact with the V groove side surface of the seal surface of the inner ring 2. (3) One end 6c of the seal member 6 is fixed to the outer ring 3, and the other end 6d is the inner ring. 2 is contacted with the side surface of the V-groove of the sealing surface, but a low-torque structure is provided by providing a suction-preventing slit or the like in the contacting lip.
In any of the above mounting methods, the surrounding ester oil comes into contact with the rubber molded body 6 b constituting the seal member 6. The rubber molded body 6b only needs to be formed of the above-described fluororubber molded body at least at a portion that contacts the ester oil. For example, the rubber molded body 6b may be a fluororubber molded body alone, or may be a laminated body in which a portion in contact with the ester oil is a fluororubber molded body and a conventional rubber molded body is laminated on the back surface thereof.
When grease that deteriorates the FKM fluororubber seal such as urea grease is used as the bearing-filled grease, it is preferable that the portion in contact with the grease is also formed of the above-described fluororubber molded body. .

The fluororubber composition for forming a fluororubber molded product according to the present invention comprises tetrafluoroethylene, propylene, and an unsaturated hydrocarbon having 2 to 4 carbon atoms in which a part of hydrogen atoms are substituted with fluorine atoms. A vulcanizable fluororubber composition comprising a copolymer containing a crosslinking monomer.
Examples of the crosslinking monomer comprising an unsaturated hydrocarbon having 2 to 4 carbon atoms in which a part of hydrogen atoms are substituted with fluorine atoms include trifluoroethylene, 3,3,3-trifluoropropene-1, Examples include 2,3,3,3-pentafluoropropene, 1,1,3,3,3-pentafluoropropylene, and 2,3,3,3-tetrafluoropropene. A preferred crosslinking monomer is 3,3,3-trifluoropropene-1.

  As a fourth component in the copolymer that can be used in the present invention, vinylidene fluoride, chlorotrifluoroethylene, perfluoro (alkyl vinyl) ether, perfluoro (alkoxy vinyl) ether, perfluoro (alkoxyalkyl vinyl) ether, perfluoroalkyl alkenyl ether, A perfluoroalkoxy alkenyl ether etc. can be mix | blended.

The copolymer constituting the fluororubber composition is 45 to 80% by weight, preferably 50 to 78% by weight, more preferably 65 to 78% by weight of tetrafluoroethylene, based on the whole copolymer. Is 10 to 40% by weight, preferably 12 to 30% by weight, more preferably 15 to 25% by weight, and the crosslinking monomer is 0.1 to 15% by weight, preferably 2 to 10% by weight, more preferably 3%. ~ 6% by weight.
When vinylidene fluoride is copolymerized, the vinylidene fluoride is 2 to 20% by weight, preferably 10 to 20% by weight. If the amount exceeds 20% by weight, the resistance to amine-based additives added to the ester oil sprayed for driving assistance may decrease, or if a urea compound is used as a thickener for the encapsulated grease, There is a risk that resistance to urea compounds may be reduced.

This fluororubber production method is disclosed in, for example, International Publication No. WO02 / 092683, and is produced by an emulsion polymerization method or a suspension polymerization method.
In order to vulcanize these fluororubbers, vulcanization accelerators selected from polyhydroxy (polyol) vulcanizing agents, quaternary ammonium salts, fourth phosphonium salts, third sulfonium salts, etc., calcium hydroxide and magnesium oxide Etc., fillers such as carbon black, clay, barium sulfate, calcium carbonate and magnesium silicate, processing aids such as octadecylamine and wax, heat aging inhibitors and pigments can be blended. For example, each blending amount is 0.1 to 20 parts by weight, preferably 0.5 to 3 parts by weight of the vulcanizing agent, and 0.1 to 20 parts by weight of the vulcanization accelerator, preferably 0.5 to 100 parts by weight of the copolymer. 3 parts by weight, acid acceptor 1-30 parts by weight, preferably 1-7 parts by weight, filler 5-100 parts by weight, and processing aid 0.1-20 parts by weight.

  In addition to these, a second vulcanizing agent such as an organic peroxide compound may be added in an amount of 0.7 to 7 parts by weight, preferably 1 to 3 parts by weight. In addition, fillers and additives that can be blended in general rubber compositions should be used as long as they do not impair the resistance and sealing properties of amine compounds in ester oils and urea compounds that are thickeners. Can do.

  As a method of mixing or molding these compositions, a process used for general rubber processing can be adopted. After kneading with an open roll, a Banbury mixer, a kneader, various sealed mixers, etc., press molding (press processing) Sulfur), extrusion molding, injection molding, etc. In order to improve the characteristics, it is preferable to perform secondary vulcanization after molding, and this is performed by sufficiently heating in an oven (for example, 200 ° C. for 24 hours). The rubber molded body is obtained through the molding and vulcanization steps.

  The rubber hardness of the rubber molded body that can be used in the present invention is 60 ° to 90 °. Preferably, it is 70 ° -80 °. If it is less than 60 °, it becomes too soft and wear resistance decreases, and if it exceeds 90 °, the rotational torque becomes too large and the temperature of the rolling bearing rises. The rubber hardness (degree) was measured according to JIS K 6253.

  The grease enclosed in the rolling bearing for the tenter clip of the present invention is based on fluorine oil such as perfluoropolyether (hereinafter referred to as PFPE) oil in consideration of heat resistance in the transverse stretching apparatus that performs heat treatment. Fluorine grease using PTFE resin powder as a thickener alone or a base oil that is a mixed oil of fluorine oil and ester oil and a grease containing a mixture of diurea compound and PTFE resin powder as a thickener Is preferred.

また、Ｒ₁ およびＲ₃ は、１価の脂肪族基、脂環族基または芳香族基をそれぞれ表す。特に、Ｒ₁およびＲ₃ が脂肪族基である脂肪族ジウレアを増ちょう剤とするウレア系グリースがフッ素グリースと容易に混合するので好ましい。なお、ウレア化合物の製造方法の一例としては、ジイソシアナート化合物にイソシアナート基当量のアミン化合物を反応させる方法が挙げられる。 The urea compound blended as a thickener contains a urea bond (—NHCONH—) in the molecule, and examples include diurea, triurea, tetraurea, urea urethane, and the like. A preferred urea compound is diurea having two urea bonds in the molecule, and is represented by the following chemical formula 1. R ₂ is a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and is specifically represented by the following chemical formula 2.

R ₁ and R ₃ each represent a monovalent aliphatic group, alicyclic group or aromatic group. In particular, a urea-based grease using an aliphatic diurea in which R ₁ and R ₃ are aliphatic groups as a thickener is preferable because it easily mixes with fluorine grease. In addition, as an example of the manufacturing method of a urea compound, the method of making the amine compound of an isocyanate group equivalent react with a diisocyanate compound is mentioned.

As ester oils, diester oils, polyol ester oils or complex ester oils thereof, aromatic ester oils and the like can be used.
Specific examples of ester oils include, for example, esters of monohydric alcohols having 7 to 22 carbon atoms and aromatic polyvalent carboxylic acids or derivatives thereof, and monovalent carboxylic acids having 7 to 22 carbon atoms and aliphatic polyvalent acids. Mention may be made of at least one ester oil selected from esters with alcohols. In monohydric alcohols and monohydric carboxylic acids, if the carbon number is less than 7 and the carbon number exceeds 22, the lubricity is poor.

Examples of the monohydric alcohol having 7 to 22 carbon atoms include heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, oleyl alcohol, stearyl alcohol, phenol, methylphenol, octylphenol, and other alkylphenols. .
The monovalent carboxylic acid having 7 to 22 carbon atoms is a monovalent carboxylic acid in which —CH ₂ OH of the aliphatic monohydric alcohol is replaced with —COOH, or —OH of the aromatic monohydric alcohol. A monovalent carboxylic acid substituted for -COOH can be mentioned.
Examples of the aromatic polycarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, diphenyltetracarboxylic acid, and benzophenonetetracarboxylic acid.
Examples of the aliphatic polyhydric alcohol include 1,3 butylene glycol, glycerin, propylene glycol, ethylene glycol, pentadiol, diethylene glycol, polyethylene glycol, polypropylene glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol and the like.

  When grease containing urea as a thickener comes into contact with an FKM fluororubber seal at high temperatures, urea or unreacted amine crosslinks the vinylidene fluoride portion of FKM, and there is a problem that the rubber cures and deteriorates. Since the fluororubber molded product used in the tenter clip rolling bearing of the present invention is excellent in resistance to urea and amine, there is an advantage that such a problem does not occur.

The fluororubber compositions used in each example and comparative example are shown below.
An unvulcanized fluororubber composition was obtained by kneading using an open roll at a roll temperature of 50 ° C. with the composition shown in Table 1. Each material used in Table 1 is shown below.
(1) Fluororubber 1: DuPont Dow Elastomer, VTR8802 (with vulcanizing agent)
(2) Fluoro rubber 2: DuPont Dow Elastomer, A32J
(3) Magnesium oxide: Kyowa Chemical Industry Co., Ltd. Kyowa Mug 150
(4) Calcium hydroxide: Omi Chemical Industries, Calbit (5) Carbon: Engineered, N990
The fluororubber 1 is made of a copolymer containing tetrafluoroethylene, propylene, and a crosslinking monomer composed of an unsaturated hydrocarbon having 2 to 4 carbon atoms in which some of the hydrogen atoms are substituted with fluorine atoms. It is a vulcanizable fluoro rubber, and the fluoro rubber composition 2 is a vinylidene fluoride rubber.

Example 1 and Comparative Example 1
A vulcanized molded product was obtained with a vulcanizing press using the unvulcanized fluororubber composition. Primary vulcanization was performed for 12 minutes while maintaining the actual mold temperature at 170 ° C. Next, the vulcanized molded product was transferred into a thermostat and subjected to secondary vulcanization at 200 ° C. for 24 hours.
The obtained vulcanized molded product was punched into the shape of a JIS K 6251 No. 3 test piece to prepare a test piece. 170 ° C x 500 hours conditions for the test piece to ester oil (manufactured by Nippon Steel Chemical Co., Ltd., Hatcoal H2362 [kinematic viscosity at 40 ° C 70 mm ² / sec] and 2 wt% amine antioxidant [alkylated diphenylamine] added) The volume before and after immersion was measured and the volume change rate was calculated. The volume was measured according to JIS K 6258. The volume change rate was calculated according to the following formula. The results are also shown in Table 1.
Volume change rate (%) = 100 × (volume after immersion−volume before immersion) / volume before immersion

実施例１は、長時間の浸漬でも劣化が軽微であり、エステル油に対して優れた耐性を有していた。
比較例１は、エステル油に浸漬された場合の体積変化が著しい。浸漬後、500 時間では、試験片の表面に溶解がみられた。

In Example 1, the deterioration was slight even when immersed for a long time, and it had excellent resistance to ester oil.
In Comparative Example 1, the volume change when immersed in ester oil is significant. After 500 hours of soaking, dissolution was observed on the surface of the test piece.

  Since the rolling bearing for tenter clips of the present invention has excellent ester oil resistance, it can be suitably used for a rolling bearing used under conditions in contact with ester oil.

It is a figure which shows an example of a tenter clip. It is sectional drawing of the rolling bearing for tenter clips. It is sectional drawing of the rolling bearing seal member for a tenter clip. It is a figure which shows an example of the biaxially stretched film manufacturing apparatus of resin. It is a figure which shows the guide rail of the horizontal extending | stretching apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Deep groove ball bearing 2 Inner ring 3 Outer ring 4 Rolling element 5 Cage 6 Seal member 7 Grease composition 8a Opening 8b Opening 9 Extruder 10 Die head (T die)
DESCRIPTION OF SYMBOLS 11 Longitudinal stretching machine 12 Guide rail 13 Lateral stretching apparatus 14 Winding winder 15 Tenter clip 15a Tenter clip main body 16 One end of sheet 17 Gripping part 18 Rolling bearing for tenter clip

Claims (3)

A film stretching apparatus comprising a plurality of tenter clips moving along a guide rail, the tenter clips being exposed to 200 to 250 ° C. and lubricated with a running assist ester oil containing an amine-based additive While having a rolling bearing in contact with the guide rail,
The rolling bearing includes an inner ring, an outer ring in contact with the guide rail on the outer periphery, a plurality of rolling elements interposed between the inner ring and the outer ring, one end fixed to the outer ring and the other end in contact with the inner ring, and the inner ring And a seal member that covers the openings on both ends in the axial direction of the outer ring, and a mixture of a fluorine grease alone or a base oil that is a mixed oil of fluorine oil and ester oil, and a diurea compound and polytetrafluoroethylene resin powder A grease consisting of a thickener that is
The seal member includes at least a portion that contacts the running assist ester oil on the outside of the bearing and a portion that contacts the encapsulated grease, and is formed of a fluoro rubber molded body.
The fluororubber molded product is a copolymer comprising tetrafluoroethylene, propylene, and a crosslinking monomer composed of an unsaturated hydrocarbon having 2 to 4 carbon atoms in which a part of hydrogen atoms are substituted with fluorine atoms. moldings der the vulcanizable fluororubber composition comprising is, film stretching device, wherein a rubber hardness of the molded product is 60 ° to 90 °.   The crosslinking monomer is trifluoroethylene, 3,3,3-trifluoropropene-1, 1,2,3,3,3-pentafluoropropene, 1,1,3,3,3-pentafluoro 2. The film stretching apparatus according to claim 1, wherein the film stretching apparatus is at least one monomer selected from propylene and 2,3,3,3-tetrafluoropropene.   The film stretching apparatus according to claim 1, wherein the copolymer contains vinylidene fluoride.

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