JP4572069B2 - Urethane belt and manufacturing method thereof - Google Patents

Description

  The present invention relates to a urethane belt and a method for producing the same, and more particularly to a polyurethane belt having a thin layer of polyurethane containing a siloxane bond on the surface and having a reduced coefficient of friction, and a method for producing the same.

  Conventionally, regarding a method for producing a polyurethane elastomer molded product having a reduced coefficient of friction only on the surface, as described in Japanese Patent No. 2998106, a polyurethane elastomer molded product is prepared by centrifugal molding, and the molding material is rotated. After the injection into the molding drum, a silicone oil having a terminal hydroxyl group is added to the surface of the molding material in the initial stage of curing of the molding material to form a thin layer of polyurethane elastomer having a siloxane bond on the surface of the polyurethane elastomer. It was possible to reduce the coefficient of friction while maintaining the characteristics inherent to the. (For example, patent document 1).

Patent No. 0998106

  In the polyurethane molded product described in Patent Document 1, in order to release the polyurethane molded product from the mold, it is necessary to first apply a release agent to the mold, and the molding material and the silicone oil are added separately. It was necessary and time-consuming. Furthermore, in the method described in Patent Document 1, centrifugal molding has to be adopted, and equipment such as a large motor for centrifugal molding has been required. Further, when the mold is detached from the centrifugal molding machine for molding at a high rotation speed, it becomes dangerous and there is a problem in safety. Furthermore, it has been difficult to reduce the coefficient of friction on any one or both sides.

  Further, when a friction coefficient reducing agent is added in advance during the blending of the polyurethane molded product, it is dispersed throughout the polyurethane blend, resulting in a decrease in hardness and physical properties.

  Accordingly, an object of the present invention is to provide a polyurethane belt that can be molded in a stationary state without the need to rotate a mold and that can reduce the surface friction coefficient of one of the belts, and a method for manufacturing the same.

The invention according to claim 1 is a urethane belt having a polyurethane elastomer as a base material and a tensile body embedded in a urethane elastic body, which is cured in a mold to which a release agent is adhered and then released. In the obtained urethane belt, a urethane belt forming a polyurethane layer containing a siloxane bond formed by reacting a silicone compound having active hydrogen at the terminal contained in the release agent with polyurethane on the back surface of the urethane belt. is there.

According to the second aspect of the present invention, after a molding material containing a urethane prepolymer having a terminal isocyanate group and a crosslinking agent is injected into a cavity formed by an outer mold and an inner mold, urethane is cured to mold a urethane belt. In the method for producing a urethane belt, a release agent containing a silicone compound having a terminal hydroxyl group is selectively applied to at least one mold, and the silicone compound reacts with polyurethane when the urethane is cured, so that the mold surface and polyurethane A urethane belt manufacturing method for obtaining a urethane belt in which a polyurethane layer containing a siloxane bond is formed between the layers.

  According to the present invention, a urethane belt having a polyurethane elastomer as a base material and a tensile body embedded in a urethane elastic body, which selectively includes a siloxane bond on one or both of the power transmission surface and the back surface of the urethane belt. Since it is a urethane belt formed with a polyurethane layer, there is an effect that a siloxane bond is formed only on the surface where the friction coefficient is desired to be reduced, and further, the friction coefficient is not lowered over time.

  According to the second aspect of the present invention, the polyurethane layer containing the siloxane bond formed by the reaction of the silicone compound having active hydrogen at the terminal contained in the release agent with the polyurethane is formed on the back surface of the urethane belt. Since it is a urethane belt, the surface that reduces the friction coefficient of the belt can be selected by applying a release agent to the mold surface that forms the surface on which the friction coefficient is desired to be reduced. Friction of the belt surface facing the mold with the same man-hours as manufacturing a standard polyurethane belt by applying a mold release agent containing a silicon compound having a terminal hydrogen group to the mold. There is an effect that the coefficient can be lowered.

  According to a third aspect of the present invention, a release agent containing a silicone compound having a terminal hydroxyl group is applied to at least one mold, and the silicone compound reacts with the polyurethane during the urethane curing so that the mold surface and the polyurethane In addition to the effects of claims 1 and 2, since the urethane belt can be molded in a stationary state, the urethane belt can be molded in a stationary state. There is an effect that a facility for rotating the mold is not necessary and safety is high.

  The polyurethane cured product forming the polyurethane belt is obtained by casting and heating and curing a liquid polyurethane resin composition. Generally, as a molding method, a premix in which a polyol catalyst, a chain extender, a pigment and the like are mixed is used. A one-shot method in which a liquid and a solution containing an isocyanate component are mixed and cast and cured, and a prepolymer in which isocyanate and polyol are reacted in advance and a part of the isocyanate is modified with polyol, There is a prepolymer method in which a catalyst is added to this and cast, followed by a curing reaction. In the present invention, the prepolymer method is preferably employed.

  The isocyanate is not limited, but aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, and modified products thereof can be used. Specific examples include toluene diisocyanate (TDI), methylene diisocyanate (MDI), xylylene diisocyanate (XDI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). And MDI are preferably used.

  Examples of the polyol include ester polyols, ether polyols, acrylic polyols, polybutadiene polyols, and mixed polyols thereof. Examples of ether polyols include polyethylene ether glycol (PPG) and polytetramethylene ether glycol (PTMG). Examples of ester polyols include polyethylene adipate (PEA), polybutylene adipate (PBA), polyhexamethylene adipate ( PHA), poly-ε-caprolactone (PCL) and the like. Of these, polytetramethylene ether glycol (PTMG) is preferably used because it is excellent in moisture resistance and water resistance and can give a molded product having tough physical properties and small hysteresis loss.

In the present invention, the amine-based curing agent is not particularly limited, but 1,4-phenylenediamine, 2,6-diaminotoluene, 1,5-naphthalenediamine, 4,4′-diaminodiphenylmethane, 3 , 3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1-methyl-3,5-bis (methylthio) -2,6-diamino Benzene, 1-methyl-3,5'-diethyl-2,6-diaminobenzene, 4,4'-methylene-bis- (3-chloro-2,6-diethylaniline), 4,4'-methylene-bis -(3-chloro-2,6-diethylaniline), 4,4'-methylene-bis- (ortho-chloroaniline), 4,4'-methylene-bis- (2,3-dichloro) Nilin), trimethylene glycol-di-para-aminobenzoate, 4,4'-methylene-bis- (2,6-diethylaniline), 4,4'-methylene-bis- (2,6-diisopropylaniline), Examples include primary amine, secondary amine, tertiary amine amine compounds such as 4,4'-diaminodiphenylsulfone. The compounding amount of the amine curing agent is preferably such that the α value (NH ₂ / NCO), which is the ratio of the number of moles of NH ₂ in the amine curing agent to the number of moles of NCO in the isocyanate, is about 1. It is good to set it in the range of 0.90 to 1.10. Generally, the physical property of the cured product is the best when the α value is around 0.95, and when the α value is out of the above range, the physical property of the cured product tends to decrease.

  In the present invention, a silicone oil having active hydrogen uniformly at the terminals on the surface of the mold to be used, for example, a silicone oil represented by the structural formula 1 can be used.

  Such silicone oils are also called silicone diols, and those having a hydroxyl value of 20 to 120 and an average molecular weight of about 1000 to 6000 can be obtained as commercial products (for example, KF-6003 manufactured by Shin-Etsu Chemical Co., Ltd.). it can.

Below, an example of the manufacturing method of the urethane belt of this invention is shown.
First, prepare an outer mold and an inner mold, and if the outer mold is a toothed belt, for example, it is flat, or if it is a belt that conveys articles on the back of the belt and has a protrusion on the back, If the outer mold has grooves or dents in the shape of protrusions, or if it is an outer mold that forms a V-ribbed belt, it has grooves in the shape of V-ribs along the circumference of the outer mold. , Etc. are exemplified. Further, if the inner mold is a toothed belt, a groove for forming a tooth portion of the belt is formed in the longitudinal direction of the mold, and a protrusion called a nose is also provided in the longitudinal direction. Further, in the case of an inner mold for a V-ribbed belt, it has a protrusion called a notch extending in the inner mold longitudinal direction.

FIG. 1 is an example of a cross-sectional view of a mold used in the method for producing a urethane belt of the present invention. According to this, the mold 1 includes an outer mold 4 and an inner mold 5 that is inserted into the outer mold 4, and the space 6 for filling the casting elastomer is provided between the outer mold 4 and the inner mold 5. is doing.
The inner die 5 has a flat outer peripheral surface, but may be a toothed belt die provided with a groove extending in the axial direction.
And the mold release agent containing the silicone oil which has an active hydrogen at the said terminal is apply | coated to the metal mold | die which forms the surface which needs to reduce a friction coefficient continuously during use to the metal mold | die prepared above. Further, the inner die 5 is mechanically fixed to a spinning device (not shown) installed above the outer die 4 by a fastening member such as a screw, and the core wire 10 is spiraled on the outer peripheral surface while rotating the inner die 5. Wrap around. At the time of spinning, the inner die 5 is positioned directly above the outer die 4 while being suspended from the spinning device.
The core wire 10 to be used may be para-aramid fiber (trade name: Twaron, Kevlar, Technora), glass fiber (E glass, high-strength glass), or polyester fiber, and its configuration, thickness, number of twists. It is not influenced by etc.

After injecting a predetermined amount of liquid elastomer into the outer mold 4 installed on the movable table 15 in advance, the table 15 is moved right above, and the outer mold 4 is inserted into the inner mold 5. The inner mold 5 is placed in the outer mold 4 and separated from a fixing member such as a screw of the spinning device. Thereafter, the upper lid 16 is closed and the inside of the mold is sealed and decompressed to remove bubbles in the liquid elastomer, and then the liquid elastomer is allowed to flow upward.
In addition, since the moving direction of the outer mold 4 is set and the inner mold 5 is fixed in position, there is little deviation between the center positions of the outer mold 4 and the inner mold 5, and the thickness of the belt molded body 8 becomes uniform. .
In addition, it is not necessary to cast the liquid elastomer into the outer mold 4 in advance, and after the inner mold 5 is installed in the outer mold 4, the liquid elastomer is cast into the space 6 between the outer mold 4 and the inner mold 5. May be.

  When the liquid elastomer finishes rising, the upper lid 16 is removed, air is introduced into the mold and pressurized, and the liquid elastomer is cured at a predetermined temperature. The mold temperature at this time is adjusted to 80 to 150 ° C. The mold temperature can be adjusted by passing a heat medium such as steam or oil through the outer mold 4 or by placing a jacket through which the heat medium passes outside the outer mold 4.

  After the curing, as shown in FIG. 2, the outer mold 4 is moved right below to remove the outer mold 4 fitted with the belt molded body 8 from the inner mold 5, and after this is completed, the belt molded body 8 is removed from the outer mold 4.

The endless belt molded body is cut to a predetermined width to form a urethane belt. In the present invention, the toothed belt of FIG . 4, the V-ribbed belt shown in FIGS. 5 to 7, and the conveyance belt with protrusions shown in FIG. 9 are exemplified, but not limited thereto.

A pair of inner and outer molds for preparing a sheet is prepared, and a low viscosity silicone oil D having a viscosity of 90 cp having a component as a release agent in the inner mold and an active hydrogen at the terminal, and a viscosity of 1 × 10 ³ A silicone oil composed of cp silicone oil B and an aqueous release agent (FRX-M52) containing a fluorine compound and a wax were used. At this time, silicone oil B was blended less than silicone oil D. The release agent was uniformly applied to the inner mold. Next, an outer mold in which a predetermined amount of a liquid polyurethane raw material (100 parts by mass of a prepolymer, 12 parts by mass of a curing agent that is 3,3′-dicyclo4,4aminodiphenylmethane, 0.2 parts by mass of a catalyst) is cast in advance. It was moved and inserted into the inner mold. The inside of the space is sealed with an upper lid, depressurized and defoamed, the liquid polyurethane is raised, the mold is opened, air is introduced and pressurized, and the liquid polyurethane is cured at a mold temperature of 110 ° C. for 20 minutes. I let you. Thereafter, the urethane sheet was removed from the mold and aged in an atmosphere of 60 ° C. A 2 cm × 2 cm test piece was prepared from the urethane sheet, washed with isopropyl alcohol (IPA), and dried for 2 hours. Thereafter, a load of 1.96 N was placed on the test piece, the test piece was pulled at a tensile speed of 100 mm / min, and the friction coefficient was measured using a counterpart material as tetrafluoroethylene resin. The results are shown in Table 1.

  As a conventional example, a silicone compound having no active hydrogen at the terminal and a water-based mold release agent composed of a fluorine compound, a wax, an emulsifier, and water were used, and the mold release agent was uniformly applied to the same inner mold as in the examples. And the test piece was created by the method similar to an Example, and the friction coefficient of the test piece was measured on the conditions similar to an Example. The results are shown in Table 1.

  As Comparative Example 1, the same silicone compound as in the conventional example and fluorine compound, or a water-based mold release agent composed of wax and silicone rubber powder, emulsifier, and water having a melting point higher than that of the conventional example were used to carry out the release agent. It was uniformly applied to the same inner mold as the example. And the test piece was created by the method similar to an Example, and the friction coefficient of the test piece was measured on the conditions similar to an Example. The results are shown in Table 1.

As Comparative Example 2, a normal particle outer surface having a primary particle diameter of about 12 nm is chemically decorated from Si—OH (hydrophilic) to Si (CH ₃ ) ₂ (hydrophobic), and a release agent composed of an emulsifier and water is used. did. Then, the silica powder was transferred to the molded urethane surface to increase the surface roughness, thereby reducing the friction coefficient. A test piece was prepared in the same manner as in the example, and the coefficient of friction of the test piece was measured under the same conditions as in the example. The results are shown in Table 1.

As Comparative Example 3, a conventional release agent was used, and 5 parts by mass of higher fatty acid was added to the urethane formulation.
And the release agent of the prior art example was uniformly apply | coated to the same internal mold as an Example. And the test piece was created by the method similar to an Example, and the friction coefficient of the test piece was measured on the conditions similar to an Example. The results are shown in Table 1.

  As can be seen from Table 1, the friction coefficient of the examples is small both when the surface is wiped before measurement and when the surface is not wiped. In Comparative Example 3 in which a higher fatty acid was added to the urethane compound, the same coefficient of friction as that of the Example was obtained when the surface was not wiped before the measurement. The friction coefficient increases. From this, it can be seen that the friction coefficient during use can be reduced in the example even on the belt before use and on the conveying surface of card conveyance or the tooth side of the toothed belt.

  The present invention is a standard for continuously preventing the sound generation of a toothed belt made of urethane, a V-belt, and a V-ribbed belt, and a polyurethane conveyor belt for card conveyance, coin conveyance, etc., and the coefficient of friction of the conveyance surface is continuously maintained. It can be used when you want to keep it below.

It is an example of sectional drawing of an example metal mold | die used for the manufacturing method of the urethane belt of this invention. It is sectional drawing which shows the state which has released the inner type | mold and the outer type | mold in the manufacturing method of this invention. It is a figure showing the belt fabrication object concerning the present invention. It is a polyurethane toothed belt of the present invention, (a) is a partially broken perspective view, (b) is a sectional view. It is a perspective view of the polyurethane V-ribbed belt of the present invention. It is a perspective view of the truncated V-ribbed belt of the present invention. It is sectional drawing of the polyurethane V-ribbed belt of this invention. It is sectional drawing of the V belt made from polyurethane of this invention. It is a perspective view showing the conveyance belt with a projection of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal mold | die 4 Outer mold | type 5 Inner mold | type 6 Space part 8 Belt molded object 10 Core wire 16 Cover

Claims (2)

  A urethane belt comprising a polyurethane elastomer as a base material and a tensile body embedded in a urethane elastic body, wherein the urethane belt is obtained by curing in a mold to which a release agent is adhered and then releasing the mold. A polyurethane belt comprising a siloxane bond formed by reacting a silicone compound having active hydrogen at the terminal contained in the release agent with polyurethane on the back surface of the urethane belt. In a method for producing a urethane belt, a molding material containing a urethane prepolymer having a terminal isocyanate group and a crosslinking agent is injected into a cavity formed by an outer mold and an inner mold, and then urethane is cured to form a urethane belt. A mold release agent containing a silicone compound having the following is selectively applied to at least one mold, and the silicone compound reacts with polyurethane during urethane curing to include a siloxane bond between the mold surface and the polyurethane layer. A method for producing a urethane belt, comprising obtaining a urethane belt having a polyurethane layer formed thereon.

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