JPH05209182A - Receiving material for rotating drum - Google Patents

Abstract

PURPOSE:To provide the subject low-friction receiving material for a rotating drum, excellent in abrasion resistance characteristics and heat resistance and having stability and reliability for a long period while absorbing the vibration. CONSTITUTION:The objective receiving material 3 for a rotating drum 1 is equipped with a sliding surface, receiving the rotating drum 1 and formed of a lubricating rubber composition comprising a thermoplastic fluororesin which is the first essential component, a fluororubber which is the second essential component and a low-molecular weight fluorine-containing polymer which is the third essential component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving material for receiving a rotating drum such as a dryer drum.

[0002]

2. Description of the Related Art As a rotary drum, for example, a drum for a dryer is known. The drum for this dryer is generally supported by a cantilevered shaft, and a belt is wound around the outer periphery of the drum and is rotated by rotating the belt. As a member for receiving this drum, generally 3 to 5 receiving members are provided. The bearing material for such a rotary drum is required to have heat resistance, low friction characteristics, low wear resistance, and vibration absorbability capable of withstanding high-speed sliding at 70 to 100 m / min.

Conventionally, a sheet member such as a diene-based synthetic rubber having a Teflon sheet attached to the surface has been mainly used.

[0004]

However, since it is exposed to high temperature for a long period of time and frictional sliding heat is added,
The rubber easily deteriorates, and peeling of the adhesive part becomes a problem. Further, since the sliding surface is not an elastic body, sliding absorbency is not sufficiently satisfied.

As a measure for improving the vibration absorbing property, a type in which a diene rubber material is impregnated with oil has been studied, but the oil is discharged over time, the sliding resistance gradually increases, and stick slip or the like occurs. Occurred and damage occurred. Further, Teflon coating on a rubber material was also tried, but there was a problem of heat resistance of the rubber material, and usable ones were not sufficient in abrasion resistance.

Olefinic polymers such as polyethylene have been investigated, but there was a problem of surface softening due to sliding heat generation. A thermosetting resin such as a phenolic resin to which a fluororesin was added was also examined, but vibration absorption was almost impossible.

Further, a diene rubber to which a solid lubricant such as Teflon or silicone was added to give low frictional properties was also studied, but addition of both results in high hardness and insufficient sealing property. However, there are problems such as deterioration in tensile strength and tear strength, and inferior wear resistance to conventional products, making it unusable for practical use.

Silicon rubber and fluororubber were also targeted, but their superiority was not recognized.

On the other hand, in a drum for a dryer, a speed change operation such as a speed increase and an oscillating motion is required for the purpose of drying in a shorter time in recent years. A drum receiving material having excellent heat resistance is desired.

An object of the present invention is to provide a rotary drum support member which absorbs vibrations, has low friction, is excellent in wear resistance and heat resistance, and has stability and reliability for a long period of time.

[0011]

A rotary drum receiving member according to the present invention has a sliding surface for receiving a rotating drum, and at least the sliding surface is formed of a lubricating rubber composition. It is characterized in that it contains a thermoplastic fluororesin which is the first essential component, a fluororubber which is the second essential component, and a low molecular weight fluoropolymer which is the third essential component.

In the present invention, the thermoplastic fluororesin which is the first essential component is a polymer having a carbon chain in the main chain and a fluorine bond in the side chain. Examples of such a thermoplastic fluororesin include tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (hereinafter abbreviated as PFA), tetrafluoroethylene.
Hexafluoropropylene / perfluoroalkyl vinyl ether copolymer (hereinafter abbreviated as EPE), tetrafluoroethylene / hexafluoropropylene copolymer (hereinafter abbreviated as FEP), tetrafluoroethylene /
Ethylene copolymer (hereinafter abbreviated as ETFE), trifluorochloroethylene polymer (hereinafter abbreviated as CTFE), trifluorochloroethylene / ethylene copolymer (hereinafter abbreviated as ECTFE), polyvinyl fluoride (hereinafter PVF and (Abbreviated) and polyvinylidene fluoride (hereinafter abbreviated as PVDE) are preferably one or more polymers selected from the group consisting of: In particular, ETFE, PFA and FEP are preferable in consideration of not forming fibers in the kneading step, ease of kneading such as meltability, and maintenance of rubber-like elasticity of the final product. In ETFE, MI value (melt index) is 300 ° C, 216
It is preferably 1 to 20 g / 10 min at 0 g.

Any of the above resins can be produced by various polymerization methods such as catalyst emulsion polymerization, suspension polymerization, catalyst solution polymerization, gas phase polymerization and ionizing radiation irradiation polymerization. It is desirable that the molecular weight is 50,000 or less.
It is particularly preferable that the value exceeds 00 and is almost 20000 or less.

As a typical example corresponding to the above conditions, the above-mentioned PFA PF manufactured by Mitsui DuPont Fluorochemical Co., Ltd.
AMP10, FEP Teflon FEP100 manufactured by Mitsui DuPont Fluorochemicals, ETFE Aflon COP manufactured by Asahi Glass Co., Ltd. CTFE, NEOFLON CTFE manufactured by Daikin Industries, KPV manufactured by Kureha Chemical Co., Ltd.
Examples include polymers and PVF Tedlar manufactured by DuPont.

In the present invention, the fluororubber is a polymer or copolymer of unit monomers containing an average of one or more fluorine atoms, has a glass transition temperature of room temperature or lower, and exhibits rubber-like elasticity at room temperature. There is no particular limitation as long as it has, and a wide range can be exemplified.

Examples of the polymerization method of fluororubber include bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, catalyst polymerization, ionizing radiation polymerization, and redox polymerization. Further, the molecular weight of the fluororubber is usually preferably 50,000 or more, and the one having a high molecular weight as much as possible obtains a good result. Therefore, it is more preferably 70,000 or more, particularly preferably 100,000 to 250,000. Use one.

Typical examples corresponding to the above conditions are tetrafluoroethylene / propylene copolymer Afras manufactured by Asahi Glass Co., Ltd., vinylidene fluoride / hexafluoropropylene copolymer DuPont / Showa Denko Viton, and fluorine. Montefluos technoflon, which is a vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene copolymer, Silastic LS, a fluorosilicone elastomer, Dow Corning, PNF, a phosphazene elastomer, PNF,
And a perfluoroelastomer such as Daiel Perflo manufactured by Daikin Industries, Ltd.

The composition obtained by mixing the above-mentioned fluororubber and thermoplastic fluororesin has characteristics as an elastic body. In the present invention, the low molecular weight fluoropolymer, which is the third essential component, is added in order to impart even more excellent sliding properties to such an elastic body.

In the present invention, the low molecular weight fluorine-containing polymer means tetrafluoroethylene (TFE), a fluoropolyether having a main structural unit —C _n F _2n —O— (n is an integer of 1 to 4), Structural unit

[0020]

[Chemical 1]

Among the polyfluoroalkyl group-containing compounds (having 2 to 20 carbon atoms) having, for example, those having a molecular weight of 50,000 or less. In order to impart excellent sliding properties, it is particularly preferable that the low molecular weight fluoropolymer has a molecular weight of 5,000 or less. Among such low molecular weight fluorinated polymers, those having an average particle size of 5 μm or less of the tetrafluoroethylene polymer represented by the following formula are particularly preferable.

[0022]

[Chemical 2]

Examples of such materials include Bydax AR manufactured by DuPont, and Fluon Lubricant L169 manufactured by Asahi Glass Co., Ltd.

Next, (the n 1 to 4 integer) -C _n F _2n -O- mean molecular weight of 50,000 or less fluoropolyethers having a main structural unit of,

[0025]

[Chemical 3]

For example, Such polymers are those having a structural unit containing a functional group such as an isocyanate group, a hydroxyl group, a carboxyl group, and an ester group in order to improve the affinity (adhesion) with other compounding materials and additives. desirable.

Specific examples of such a fluoropolyether include the following.

[0028]

[Chemical 4]

These fluoropolyethers may be used alone or in combination. Further, a fluoropolyether having activated hydrogen as a functional group and an isocyanate compound having no polyfluoropolyether group may be used in combination. Further, a fluoropolyether having an isocyanate group, diamines not containing various fluoropolyether groups, triamines, or diols not containing various fluoropolyether groups,
A method of using triols together may be adopted.

Particularly, it is preferable to use a combination of fluoropolyethers in which functional groups react with each other to increase the molecular weight. As such, it is likewise desirable to combine, for example, those having units containing isocyanate groups with those having units containing hydroxyl groups.

Examples of the polyfluoroalkyl group-containing compound include compounds having a polyfluoroalkyl group as shown below.

[0032]

[Chemical 5]

Those having the above polyfluoroalkyl group (having 2 to 20 carbon atoms) and having an average molecular weight of 50,000 or less include:

[0034]

[Chemical 6]

And the like, a polymer of a reaction product (for example, a fluoroalkyl acrylate) of a compound having a reactive group and a polyfluoroalkyl group with an ethylenically unsaturated compound having a group which reacts with the reactive group, and Examples thereof include a reaction product of a compound having a reactive group and a polyfluoroalkyl group with various polymers having a group that reacts with the reactive group, or a polycondensation product of the compound.

Like the above-mentioned fluoropolyether, the polyfluoroalkyl group-containing compound is a functional group having a high affinity for improving the affinity (adhesion) with other compounding materials and additives, such as an isocyanate group, A compound having a unit containing a hydroxyl group, a mercapto group, a carboxyl group, an epoxy group, an amino group, a sulfone group and the like is preferable.

These polyfluoroalkyl group-containing compounds may be used alone or in combination. Further, a polyfluoroalkyl group-containing compound having a reactive group having activated hydrogen and an isocyanate compound having no polyfluoroalkyl group may be used in combination. Also,
Adopting a method such as combining a polyfluoroalkyl group-containing compound having an isocyanate group with various polyfluoroalkyl group-free diamines, triamines or various polyfluoroalkyl group-free diols, triols, etc. May be.

The combination of functional groups is preferable from the viewpoint of increasing the strength, and specifically, it has a polyfluoroalkyl group having 2 to 20 carbon atoms and is selected from a hydroxyl group, a mercapto group, a carboxyl group and an amino group. Combination with a fluorine-containing polymer containing at least one kind, or 2 to 20 carbon atoms
A fluoropolymer having a polyfluoroalkyl group and having a unit containing an isocyanate group, and having 2 to 2 carbon atoms.
There may be mentioned a combination with a fluoropolymer having 20 polyfluoroalkyl groups and further having a unit containing a reactive group having activated hydrogen.

Among these low molecular weight fluoropolymers,
Use of tetrafluoroethylene polymer or fluoropolyether gives excellent results in lubricity,
In particular, it has been found that the use of a tetrafluoroethylene polymer having an average particle size of 5 μm or less gives the most desirable results.

In the present invention, the compounding ratio of the fluororubber and the thermoplastic fluororesin is preferably such that the weight ratio of the fluororubber and the thermoplastic fluororesin is 50:50 to 95: 5. The blending weight ratio of the thermoplastic fluororesin is 5
If it exceeds 0/100, sufficient elasticity cannot be obtained for the intended composition, and if it is less than 5/100, sufficient abrasion resistance cannot be obtained.

The low molecular weight fluoropolymer is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the total of the fluororubber and the thermoplastic fluororesin. This is because if the compounding ratio of the low molecular weight fluoropolymer is less than 5 parts by weight, sufficient sliding properties cannot be obtained, and if it exceeds 50 parts by weight, the rubber-like elastic properties are impaired.

Further, with respect to the above-mentioned lubricating rubber composition, 3
Abrasion resistance can be improved by adding a cured powder of a thermosetting resin that does not melt at 00 ° C. or a heat-resistant resin powder having a glass transition point of 300 ° C. or higher.

The thermosetting resin powder is a fine powder of a phenol resin, an epoxy resin or the like after thermosetting, and the heat-resistant resin having a glass transition point of 300 ° C. or higher is a polyimide resin, an aromatic aramid resin or the like. Fine powder can be used.

Among the commercially available resin powders, the hardened and ground product of the phenol resin is Bellbell H300, manufactured by Kanebo.
The hardened and ground product of the polyimide resin is manufactured by Mikasa Sangyo Co., Ltd .:
As a pulverized product of PWA20 and an aromatic aramid resin, Asahi Kasei Corporation: MP-P, and as a thermosetting resin powder having a glass transition point Tg of 300 ° C. or higher, Ube Industries: Upilex S (Tg> 500), etc. is there.

The particle size of such thermosetting resin powder is 1
Those having a particle size of up to 15 μm are preferable from the viewpoint of maintaining rubber-like elasticity and facilitating the kneading process. The thermosetting resin powder is preferably added in an amount of 5 to 20% by weight with respect to the first to third essential components. If it is less than 5% by weight, there is no effect of improving wear resistance and
If the amount is more than 10% by weight, the rubber elasticity decreases, which is not preferable.

In addition to the above components, various additives may be added within the range not impairing the object of the present invention. For example, as a vulcanizing agent for fluororubber, isocyanurate, organic peroxide, etc., antioxidants such as sodium stearate, magnesium oxide, and calcium hydroxide, or acid acceptors, antistatic agents such as carbon, silica and It goes without saying that fillers such as alumina, other metal oxides, colorants, flame retardants and the like may be added as appropriate.

The method for mixing the above various raw materials is not particularly limited, and the generally-used methods can be used for mixing. For example, the elastomer as the main raw material and the other raw materials may be individually mixed sequentially or simultaneously by a roll mixer or other mixer. At this time, it is desirable to provide a temperature controller to prevent heat generation due to friction.

When a roll mixer is used,
For finishing mixing, it is more preferable to tighten the roll interval to about 3 mm or less and perform thin threading.

The rotary drum support material according to the present invention does not require a particularly limited means in the molding process, and the primary vulcanization (for example, 14
10 to 30 minutes at 0 to 170 ° C, 5 to 10 kgf / c of pressure
m ² ) and then secondary vulcanization (for example, 200 to 300 ° C.).
It can be molded for 2 to 20 hours without applying pressure.

Further, in the present invention, only the sliding surface is molded with the lubricating rubber composition containing the above-mentioned first to third essential components, and the other parts are compound-molded with general synthetic rubber, plastic or metal. May be.

As the general synthetic rubber at this time, vulcanized rubber such as nitrile rubber, chloroprene rubber, butadiene rubber, urethane rubber, styrene rubber, butyl rubber, acrylic rubber, silicone rubber, ethylene rubber, and fluorine rubber, or urethane, polyester. , Thermoplastic elastomers such as polyamide, vinyl chloride, polybutadiene, and soft nylon, and liquid elastomers such as liquid urethane and liquid butadiene.

[0052]

The lubricating rubber composition used at least on the sliding surface according to the present invention is extremely excellent in wear resistance, low friction property and sealing property. Therefore, the rotary drum receiving member according to the present invention can be used stably and reliably for a long period of time while absorbing vibration.

[0053]

1 is a sectional view showing a rotary drum of a dryer according to an embodiment of the present invention. With reference to FIG. 1, the rotary drum 1 is rotatably supported by a support shaft 7. A heater 6 for heating the inside of the rotary drum 1 is provided outside the rotary drum 1. At one end of the rotary drum 1, a tubular portion 1a having a slightly reduced diameter is formed. A frame 2 is provided around the tubular portion 1a, and an end portion of the frame 2 is also provided with the tubular portion 2a. The drum receiving member 3 is attached to the inside of the cylindrical portion 2a.

FIG. 2 is a sectional view showing the cylindrical portion of the rotary drum of FIG. 1 and the drum receiving member. Referring to FIG. 2, the tubular portion 1a
The drum receiving members 3, 4 and 5 are attached to the inside of the cylindrical portion 2a of the frame 1 around the.

FIG. 3 is a perspective view showing the rotary drum.
Referring to FIG. 3, a belt is wound around the outer periphery of rotary drum 1, and this belt is rotated by motor 8. The convection fan 9 is also rotated by the motor 8.

FIG. 4 is a perspective view showing a frame to which the drum receiving member is attached. Drum receiving members 3, 4 and 5 are attached to the inside of the cylindrical portion 2 a of the frame 2.

In this embodiment, as the drum receiving members 3, 4 and 5, a lubricating rubber composition containing the first to third essential components is used. The test results for this lubricating rubber composition are shown below.

Examples 1 to 3 First, fluororubber was wrapped around a roll mixer adjusted to have a roll interval of about 5 to 10 mm, and sodium stearate, MT carbon, ETFE and M were successively added at the ratios shown in Table 1.
gO and Ca (OH) ₂ etc. were added and kneaded. Then, the roll interval was adjusted to 1 mm, and mastication was performed about 10 times. For the purpose of preventing frictional heat at this time, cooling water was constantly passed through the roll to keep the roll temperature at 60 ° C or lower. Next, cooling water is stopped, steam is passed through the rolls, the rubber temperature is adjusted to 70 ° C or higher and 90 ° C or lower, and then the roll interval is returned to about 5 to 10 mm,
While adding the low molecular weight fluoropolymer little by little, Table 1
Kneading was carried out at the compounding ratio of each example shown in. Then, the roll interval was again narrowed to 1 mm and mastication was performed about 10 times.

Raw materials used in Examples and Comparative Examples are collectively shown below. The abbreviations are shown in []. In addition, the mixing ratio of each component is all% by weight, but (6)
The raw materials shown in (17) and (19) to (24) are% by weight based on 100 of the total weight of the raw materials shown in (1) to (5) and (18).

(1) Vinylidene fluoride / fluoropropylene copolymer [Technoflon] (Technoflon FOR420 manufactured by Asahi Monte Co., Ltd.) (2) Tetrafluoroethylene / propylene copolymer [AFLAS] (Asahi Glass / Nippon Synthetic Rubber Co., Ltd.) Made: AFLA
S 150P) (3) Fluorosilicone type elastomer (Silastic LS manufactured by Dow Corning) (4) Tetrafluoroethylene / ethylene copolymer [ETFE] (Aflon COP manufactured by Asahi Glass Co., Ltd.) (5) Tetrafluoroethylene per Fluoroalkyl vinyl ether copolymer [PFA] (Mitsui DuPont Fluorochemical Co., Ltd .: PFA-MP10) (6) Low molecular weight fluoropolymer [low molecular weight TFE]
(Asahi Glass Co., Ltd .: Lubricant L169) (7) Low molecular weight fluorine-containing polymer [low molecular weight FPE (fluoropolyether)] (Japan Enimont Co .: Fomblin Z-Doll) (8) High molecular weight PTFE (Mitsui DuPont Fluoro) Chemical Co., Ltd .: Teflon 7J (9) Carbon (van der Wirt Co .: MT carbon) (10) Sodium stearate (general industrial material) (11) Organic peroxide (α, α′-bis (t-butyl) (Peroxy) diisopropylbenzene) (12) Polyfunctional monomer [TAIC] (triallyl isocyanurate) (13) Magnesium oxide (general reagent) (14) Calcium hydroxide (general reagent) (15) Phenolic resin (Kanebo Ltd.) (Bell Pearl H300) (16) Imide resin (Ube Industries, Ltd .: Upilex S) (17) Imide resin (Mikasa Sangyo Co., Ltd .: PWA20) (18) NBR (Nippon Synthetic Rubber Co., Ltd .: N237H) (19) HAF carbon (20) JSR AROMA (21) Anti-aging agent (22) Vulcanization accelerator CZ (23) Vulcanization accelerator TT (24) Sulfur 150 × 1 using the compound obtained in the above process
Primary vulcanization of a 50 x 2t sheet (170 ° C, 10 minutes,
It was obtained at a pressing pressure of 7 kgf / cm ² . Further, secondary vulcanization (230 ° C., 16 hours, free) was performed to perform vulcanization.

The test piece obtained as described above was processed into an inner diameter of φ17 and an outer diameter of φ21 and bonded to an SPCC ring piece of φ17 × φ21 × 10 to obtain a ring test piece. The mating material was a disc-shaped test piece of SUJ2 (bearing steel) φ6 × φ33 × 6, and was evaluated using a thrust type abrasion friction tester. The conditions are a sliding speed of 128 m / min and a surface pressure of 3.5.
It was set to kgf / cm ² . The friction coefficient and wear coefficient after 500 hours are shown in Table 3.

In addition, JIS-
Based on K6301, the tensile strength, elongation and hardness (JIS-A) were evaluated. The results obtained are shown in Table 3.

Examples 4 to 10 In the proportions shown in Table 1, mixed in the same manner as in Examples 1 to 3,
Molded and vulcanized. Further, the preparation of the test piece and the test method were also carried out in the same manner as in Examples 1 to 3. The measurement results are shown in Table 3.

Comparative Examples 1 to 5 In Comparative Examples 1 to 5, the raw materials were blended in the proportions shown in Table 1, and the mixing, molding and vulcanization were performed in the same manner as in Examples 1 to 3. Further, the preparation of the test piece and the test method were also carried out in the same manner as in Examples 1 to 3. Table 3 shows the measurement results
It was shown to.

Comparative Examples 6 and 7 Comparative Examples 6 and 7 were prepared by blending the raw materials shown in Table 2,
Mixing, molding, and vulcanization were performed in the same manner as in Examples 1 to 3. The test pieces were prepared and tested in the same manner as in Examples 1-3. The measurement results are shown in Table 3.

Comparative Example 8 As Comparative Example 8, glass-filled PTFE (T-1103J manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was used to prepare a test piece, and the same test method as in Examples 1 to 3 was evaluated. The results are shown in Table 3.

[0067]

[Table 1]

[0068]

[Table 2]

[0069]

[Table 3]

As is clear from the results shown in Table 3, the rotary drum bearing material according to the present invention has smaller friction coefficient and wear coefficient than those of the comparative example, and is excellent in general physical properties such as tensile strength.

[Brief description of drawings]

FIG. 1 is a sectional view showing a rotary drum of a dryer which is an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a cylindrical portion and a drum receiving member of the rotary drum of FIG.

FIG. 3 is a perspective view showing a rotary drum.

FIG. 4 is a perspective view showing a frame to which a drum receiving member is attached.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotary drum 1a cylinder part 2 frame 2a cylinder part 3,4,5 5 drum receiving material 6 heater 7 support shaft 8 motor 9 convection fan

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Claims (7)

[Claims] 1. A rotary drum receiving member having a sliding surface for receiving a rotating drum, wherein at least the sliding surface is formed of a lubricating rubber composition, and the lubricating rubber composition is a first essential component. A rotary drum receiving material comprising a thermoplastic fluororesin as a component, a fluororubber as a second essential component, and a low molecular weight fluoropolymer as a third essential component. 2. The rotary drum receiving member according to claim 1, wherein a cured powder of a thermosetting resin or a heat-resistant resin powder having a glass transition point of 300 ° C. or higher is added to the lubricating rubber composition. 3. A group in which the thermoplastic fluororesin as the first essential component comprises a tetrafluoroethylene / ethylene copolymer, a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer and a tetrafluoroethylene / hexafluoropropylene copolymer. The rotary drum receiving material according to claim 1, which is one or more selected from the following. 4. The second essential component has a molecular weight of 100,000 to 25.
The rotary drum receiving material according to claim 1, which is a fluororubber. 5. The fluororubber as the second essential component is a tetrafluoroethylene / propylene copolymer, a vinylidene fluoride / hexafluoropropylene copolymer, a vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene copolymer, The rotary drum receiving material according to claim 1, which is one or more polymers selected from the group consisting of fluorosilicone elastomers and perfluoroelastomers. 6. The low molecular weight fluoropolymer as the third essential component is selected from the group consisting of tetrafluoroethylene polymers, fluoropolyethers and polyfluoroalkyl group-containing compounds which are polymers having a molecular weight of 50,000 or less. The rotating drum receiving material according to claim 1, which is one or more kinds of polymers described above. 7. The rotary drum receiving material according to claim 1, wherein the low molecular weight fluoropolymer which is the third essential component is a tetrafluoroethylene polymer having an average particle size of 5 μm or less.