JP6214407B2 - Surface treatment method for galvanized base material, method for producing galvanized cord, and method for producing power transmission belt - Google Patents

Description

  The present invention relates to a surface treatment method for a galvanized substrate, a galvanized cord, and a transmission belt. In particular, the present invention relates to a galvanized substrate surface treatment method, a galvanized cord, and a transmission belt that can be suitably used as a reinforcing metal cord for a transmission belt such as a timing belt.

  Metal cords used as reinforcements for transmission belts such as timing belts (hereinafter also referred to as “toothed belts”) are made by twisting galvanized steel wires or stainless steel wires, and are made of rubber or urethane resin. Embedded in a belt body made of an elastomer material.

  In such a transmission belt, in order to improve the adhesion between the elastomer material and the metal cord, for example, a method of coating the surface of the steel wire constituting the metal cord with an epoxy resin layer is known. However, since an organic solvent is used, an environmentally friendly steel wire surface treatment means is required. Further, in recent years, urethane resins having excellent fatigue resistance and the like have been attracting attention as elastomer materials in timing belts and the like, and in particular, steel wires for improving adhesion to the base material urethane resin constituting the belt body. Surface treatment technology is required.

  As a surface treatment means for various materials, a treatment using a silane coupling agent is well known. The materials treated with silane coupling agents start with glass fibers, and include a wide range of materials such as inorganic materials, silica, and metal materials. However, it is difficult to ensure reactivity with metal materials, and other agents are allowed to act in combination. In most cases, a special silane coupling agent is used.

  Although the field to which the invention belongs differs from that of the present invention, for example, Patent Document 1 discloses at least one substance selected from substances containing a specific polyphenol carboxylic acid and its depside and a silane coupling having a specific structure. A technique for improving paint adhesion by treating the surface of a galvanized steel sheet with a surface treatment liquid containing an agent is disclosed.

  In the same technical field as the present invention, as a technique using a special coupling agent, for example, Patent Document 2 discloses a silane cup for improving the adhesion between a vulcanized elastomer and a metal reinforcing material. A specific coupling agent comprising, as a ring agent, a polymer main chain having an unsaturated carbon-carbon bond for reacting with a vulcanized elastomer material, and a terminal group having a specific group for bonding with a metal material Is disclosed.

  Further, as another surface treatment technique for the base material, for example, a technique for treating the base material surface with ozone water is known. Although the field to which the invention belongs is a medical field different from the present invention, for example, Patent Documents 3 and 4 disclose a technique for treating the surface of a substrate with ozone water in order to improve the adhesion of the calcium phosphate coating to the substrate. It is disclosed.

JP 7-216268 A Special table 2010-519374 International Publication No. 2009/057502 Pamphlet International Publication No. 2010/125686 Pamphlet

  As described above, various techniques are known as surface treatment means for various materials, but the adhesion between a metal base material and an elastomer material such as urethane resin that constitutes the belt body is improved easily and effectively. The fact is that there are no environmentally friendly technologies to be developed.

  The present invention provides an environment-friendly surface treatment method for a metal substrate that can effectively and effectively improve the adhesion between the metal substrate and the elastomer material constituting the transmission belt body, in a short treatment time, An object is to provide a metal cord and a transmission belt.

According to the first aspect of the present invention, a hydroxylation treatment step of introducing a hydroxyl group into the surface of the galvanized substrate by bringing an alkaline aqueous solution into contact with the surface of the galvanized substrate;
A silane coupling agent that forms a hydrogen bond between a silanol group derived from the silane coupling agent and a hydroxyl group on the surface of the galvanized substrate by bringing a silane coupling agent aqueous solution into contact with the surface of the galvanized substrate after the hydroxylation treatment Processing steps, and
A process of forming a silane coupling agent film on the surface of the galvanized substrate through SiO bond formed by dehydration condensation reaction of the silanol group and the hydroxyl group by heating the galvanized substrate after the silane coupling agent treatment A method for surface treatment of a galvanized base material is provided.

In one embodiment of the present invention, the alkaline aqueous solution is a sodium hydroxide aqueous solution.
In another embodiment of the present invention, the surface treatment method of the present invention may further include a step of oxidizing the surface of the galvanized substrate before the hydroxylation step.

  In another embodiment of the present invention, the oxidation treatment is performed by heating.

  In another embodiment of the present invention, the silane coupling is an amino silane coupling agent.

  In another embodiment of the present invention, the galvanized substrate may be a galvanized linear body or a strand obtained by twisting two or more galvanized linear bodies.

According to a second aspect of the present invention, a galvanized cord is provided.
In one embodiment of the present invention, the galvanized cord is made of a strand obtained by twisting two or more zinc linear bodies that have been surface-treated using the above-described surface treatment method for a galvanized substrate.

  In another embodiment of the present invention, the galvanized cord is made of a strand obtained by twisting two or more zinc linear bodies, and the strand is surface-treated using the above-described surface treatment method for a galvanized substrate. It is a thing.

  In another embodiment of the present invention, the galvanized cord includes a sheath strand obtained by twisting two or more galvanized wire bodies around a core strand obtained by twisting two or more galvanized wire bodies. A plurality of galvanized cords are arranged, and at least a galvanized linear body constituting the sheath strand is surface-treated by the above-described surface treatment method for a galvanized base material.

  In another embodiment of the present invention, the galvanized cord includes a sheath strand obtained by twisting two or more galvanized wire bodies around a core strand obtained by twisting two or more galvanized wire bodies. A plurality of galvanized cords are arranged, and at least the sheath strand is surface-treated by the above-described surface treatment method for a galvanized substrate.

  In another embodiment of the present invention, the galvanized cord is used as a reinforcing material for a transmission belt, for example, as a reinforcing material for a timing belt.

  According to the third aspect of the present invention, there is provided a transmission belt in which the galvanized cord described above is embedded in a belt body containing an elastomer material as a reinforcing material.

  In one embodiment of the present invention, the elastomer material contains a urethane resin.

  In another embodiment of the present invention, the transmission belt is a timing belt.

  According to the present invention, an environmentally friendly surface treatment of a galvanized base material that can improve the adhesion between the galvanized base material and the elastomer material constituting the transmission belt body in a short processing time, simply and effectively. It has become possible to provide a method, a galvanized cord and a transmission belt.

The photograph which shows the sample external appearance used in the pull-out test of an Example.

Hereinafter, embodiments of the present invention will be described in detail.
The surface treatment method for a galvanized base material according to the present invention includes a hydroxylation process in which an alkaline aqueous solution is brought into contact with the surface of the galvanized base material, and a silane coupling agent aqueous solution is brought into contact with the surface of the galvanized base material after the hydroxylation treatment. And a silane coupling agent coating forming step of heating the galvanized substrate after the silane coupling agent processing to form a silane coupling agent coating.

  That is, in the surface treatment method for a galvanized base material according to the present invention (hereinafter also referred to as “the surface treatment method of the present invention” or the like), first, the surface of the galvanized base material is contacted with an alkaline aqueous solution to thereby form a metal substrate. Hydroxyl groups are introduced on the surface of the material, and the hydrogen bond between the silanol group derived from the silane coupling agent and the hydroxyl group on the surface of the galvanized substrate is made by contacting the aqueous solution of the silane coupling agent with the surface of the zinc after the hydroxylation treatment. It is formed. Next, by heating the galvanized substrate after the silane coupling treatment, a SiO bond is formed by a dehydration condensation reaction between the silanol group and the hydroxyl group on the surface of the galvanized substrate, through which the silane coupling agent film is formed. Immobilized on the substrate surface.

  The above-described mechanism of immobilizing the silane coupling agent film by the surface treatment method of the present invention is achieved by using an aqueous solution of a silane coupling agent in the silane coupling agent treatment. 4 (see eg paragraphs 0030-0031, Examples etc.), this is not achieved by using an organic solvent solution of the silane coupling agent.

  That is, the surface of the metal substrate after the hydroxylation treatment is hydrophilic due to the presence of oxide (MO), hydroxide (M-OH), etc., and moisture is adsorbed on the surface. Since the silane coupling agent in the organic solvent is hydrophobic (Si—O—R), when the surface of the metal substrate after the alkali hydroxylation treatment is treated with an organic solvent solution of the silane coupling agent, alkaline water is used. The reaction with the substrate surface (hydrophilicity) after the oxidation treatment does not proceed easily, and the silane coupling agent film is difficult to be formed. For this reason, it is necessary to form a Si-OM bond directly between the metal substrate and the silane coupling agent film by performing the silane coupling agent treatment at a high temperature for a long time.

  On the other hand, in the surface treatment method of the present invention, since an aqueous solution of a silane coupling agent is used, as described above, a silanol group (Si—OH) (hydrophilic) derived from a silane coupling agent, and after hydroxylation treatment The hydroxyl group on the surface of the metal substrate forms a hydrogen bond, and the reaction proceeds quickly. For this reason, the silane coupling agent treatment is performed at room temperature and in a short time as will be described later. Furthermore, as a result of the heat treatment that is performed next, as described above, a SiO bond is formed by a dehydration condensation reaction between the silanol group and the hydroxyl group on the metal substrate surface, through which the silane coupling agent film is formed on the substrate surface. To be fixed.

<Galvanized base material>
The metal substrate treated by the surface treatment method of the present invention is a galvanized substrate. As a result of diligent research by the present inventors, the surface treatment method including the above-described treatment steps has dramatically improved adhesiveness with an elastomer material, particularly when applied to the surface treatment of a galvanized substrate among metal substrates. It has been found to improve.

  In one aspect of the present invention, the galvanized substrate treated by the surface treatment method of the present invention is used as a reinforcing material for a transmission belt. Here, the transmission belt is, for example, a timing belt (toothed belt), a flat belt, a V-ribbed belt, and the like, and as a metal base material used as a reinforcing material, a galvanized linear body or two or more zinc The strand which twisted the plated linear object is mentioned. Therefore, the galvanized substrate to be treated by the surface treatment method of the present invention may be a galvanized linear body or a strand obtained by twisting two or more galvanized linear bodies.

<Hydroxylation treatment>
The surface treatment method of the present invention includes a hydroxylation treatment step in which an alkaline aqueous solution is brought into contact with the surface of the galvanized substrate. By this hydroxylation treatment step, the surface of the galvanized base material is converted into an oxide (MO) or hydroxide (M-) by a chemical reaction between the base (OH ⁻ ) in the alkaline aqueous solution and zinc on the base material surface. OH) and the like become hydrophilic, and moisture is adsorbed on the surface. That is, hydroxyl groups are introduced on the surface of the galvanized base material. A silanol group derived from a silane coupling agent described later reacts with this hydroxyl group to form a hydrogen bond.

  The alkaline aqueous solution that can be used in the hydroxylation treatment step is preferably a strong alkaline aqueous solution, and examples thereof include a sodium hydroxide aqueous solution.

  The method for bringing the surface of the galvanized base material into contact with the alkaline aqueous solution is not particularly limited. For example, the galvanized base material may be immersed in the alkaline aqueous solution. Moreover, you may pour alkaline aqueous solution on a galvanization base material. In the case of immersion, any method of batch and continuous may be used. Moreover, you may apply an ultrasonic wave to a solution during immersion.

  The alkali concentration in the alkaline aqueous solution is not particularly limited, and can be appropriately set in relation to the temperature of the alkaline aqueous solution described later. When the alkali concentration is too low, the reaction speed with the substrate is slowed down, and the treatment time becomes long or the reaction effect becomes insufficient. For example, when the temperature of the aqueous alkali solution is 25 ° C., pH 11 or more is suitable. A pH of 12 or more is more preferable. On the other hand, if the alkali concentration is too high, non-uniformity of the reaction may occur, and the washing after the hydroxylation treatment will be a burden. For example, in the case of 25 ° C., pH 13.5 or less is suitable. When the alkaline aqueous solution is a sodium hydroxide aqueous solution, the concentration of sodium hydroxide is preferably 0.002% by mass or more and 1% by mass or less, and more preferably 0.02% by mass or more and 1% by mass or less. Moreover, it is preferable that it is 1 mass% or less.

  The temperature of the alkaline aqueous solution is not particularly limited, and may be set as appropriate together with the concentration of the alkaline aqueous solution depending on the hydroxylation state of the surface of the galvanized substrate. In one embodiment of the present invention, the temperature of the aqueous alkaline solution is preferably, for example, 20 to 50 ° C, and more preferably 25 to 45 ° C.

  The time for bringing the surface of the galvanized substrate into contact with the alkaline aqueous solution is not particularly limited and can be set as appropriate. In one form of the present invention, the treatment time is preferably, for example, 20 seconds to 2 minutes, and more preferably 30 seconds to 1 minute.

<Washing process>
In addition, in one form, the surface treatment method of this invention may further include the washing | cleaning process of removing the excess alkali adhering to the zinc plating base-material surface after the hydroxylation process mentioned above. This alkali removal step can be performed, for example, by washing the galvanized substrate after the hydroxylation treatment with water.

<Silane coupling agent treatment>
In the surface treatment method of the present invention, the aqueous silane coupling agent solution is brought into contact with the surface of the galvanized substrate after the alkaline aqueous solution is brought into contact therewith. The silane coupling agent that can be used here is not particularly limited. For example, from the viewpoint of water solubility, an amino-based silane coupling agent containing an amino group is preferable. Specifically, 3-aminopropyl Trietoxysilane (CAS No. 919-30-2; product name KEB-003 manufactured by Shin-Etsu Chemical Co., Ltd.), N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane (KBM-602), N-2- (Aminoethyl) -3-aminopropyltrimethoxysilane (KBM-603), 3-aminopropyltrimethoxysilane (KBM-903), 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine (KBE-9103), N-phenyl-3-aminopropyltrimethoxysilane (KBM-573), 3-isocyana And tetrapropyltriethoxysilane (KBE-9007).

  The silane coupling agent aqueous solution used in the silane coupling agent treatment step of the present invention is not limited as long as it is water in which the silane coupling agent is dissolved. A silane cup is formed through a SiO bond formed by a dehydration condensation reaction, which will be described later, by forming a hydrogen bond between a silanol group derived from a silane coupling agent and a hydroxyl group on the surface of the galvanized substrate without using any other agent. The ring agent film can be immobilized on the surface of the galvanized substrate.

  The method of bringing the silane coupling agent into contact with the surface of the galvanized substrate is not particularly limited. For example, the galvanized substrate may be immersed in an aqueous solution of the silane coupling agent or as in a shower. An aqueous solution of a silane coupling agent may be poured onto the galvanized substrate. In the case of immersion, any method of batch and continuous may be used. Further, the contact operation can be performed in the air, and for example, does not need to be performed in a nitrogen atmosphere.

  Although it does not specifically limit as a density | concentration of the silane coupling agent in a silane coupling agent aqueous solution, For example, it is suitable that it is 1-8 volume%, and 2-4 volume% is still more suitable. When the concentration of the silane coupling agent is less than 1% by volume, an action time and temperature are required. On the other hand, when the concentration exceeds 8% by volume, a large amount of the silane coupling agent adheres and the film may become too thick.

  Although it does not specifically limit as temperature of silane coupling agent aqueous solution, 20-40 degreeC is suitable and room temperature (for example, 25 degreeC) is more suitable.

  Although it does not specifically limit as time to contact the surface of a galvanized base material, and a silane coupling agent aqueous solution, For example, 30 second or more is suitable and 1 minute or more is more suitable. There is no need to contact for longer than necessary.

  In the surface treatment method of the present invention, the surface of the galvanized substrate is immersed in a water-soluble organic solvent (for example, tetrahydrofuran (THF)) after the hydroxylation treatment and before the silane coupling agent treatment. It is not necessary to remove the moisture on the substrate surface during the hydroxylation treatment. This operation is necessary when, for example, a hydrophobic organic solvent is used in the step of bringing the silane coupling agent into contact with the surface of the galvanized substrate. In the present invention, an aqueous solution of the silane coupling agent is used. Therefore, there is no need for such work and it can be performed easily.

<Silane coupling agent film forming step (heating step)>
In the surface treatment method of the present invention, the galvanized substrate after contacting with the aqueous silane coupling agent solution is heated. As a result, a SiO bond is formed by a dehydration condensation reaction between the silanol group derived from the silane coupling agent and the hydroxyl group on the surface of the galvanized substrate, through which the silane coupling agent film is immobilized on the surface of the galvanized substrate. Is done.

  Although it does not specifically limit as heating temperature, For example, it is suitable that it is 100 degreeC or more, and it is still more suitable that it is about 110 degreeC. On the other hand, if the heating temperature is too high, decomposition of the silane coupling agent, polymerization between the silane coupling agents, oxidation of the galvanized substrate, etc. may occur. And

  The heating time may be an appropriate time for removing dehydrated water, and may be, for example, about 5 minutes. When the galvanized substrate is a strand formed by twisting a plurality of metal linear bodies, for example, the heating time may be further increased in order to sufficiently dry the substrate.

  The surface treatment method of the present invention described above can be used for various applications. For example, as described above, it is useful when used in a surface treatment method for a galvanized base material used as a reinforcing material for a transmission belt such as a timing belt, a flat belt, or a V-ribbed belt. The galvanized base material treated by the surface treatment method of the present invention can dramatically improve the adhesiveness with the base material elastomer constituting the belt body of the transmission belt.

  Here, the elastomer material serving as a base material constituting the belt body is not particularly limited, but an elastomer having a structure such as amine or amide in the molecular chain is preferable, and examples thereof include a urethane resin. A urethane resin is particularly preferable from the viewpoint of fatigue resistance.

  As described above, in one aspect of the present invention, the surface treatment method of the present invention is used as a surface treatment method for a galvanized base material constituting a galvanized cord used as a reinforcing material for a transmission belt such as a timing belt. The

  In this case, the metal cord in this case is a strand formed by twisting two or more galvanized linear bodies treated by the surface treatment method of the present invention. In another embodiment, the galvanized cord is a strand obtained by treating a strand obtained by twisting two or more galvanized linear bodies with the surface treatment method of the present invention. In another embodiment, the galvanized cord includes a plurality of sheath strands obtained by twisting two or more galvanized linear bodies around a core strand obtained by twisting two or more galvanized linear bodies. The galvanized cord is a galvanized cord formed by subjecting at least the galvanized linear body constituting the sheath strand to the surface treatment method of the present invention. In another embodiment, the galvanized cord includes a plurality of sheath strands in which two or more galvanized linear bodies are twisted around a core strand in which two or more galvanized linear bodies are twisted together. The galvanized cord, wherein at least the sheath strand is surface treated by the surface treatment method of the present invention.

Examples of the present invention will be described below. The present invention is not limited to these.
<To-be-processed object>
As galvanized wire, 72C high carbon steel wire is electrogalvanized and cold-worked wire (diameter 0.15mm) is used. Codes A1, A2, A3, and A4 (see Table 1) were used as objects to be processed (coiled). In Table 1, for example, three galvanized linear bodies (diameter: 0.15 mm) twisted, and seven more galvanized cord No. The configuration of A1 is expressed as 7 × 3 × 0.15.

<Example 1-4>
[Hydroxylation treatment]
A coiled galvanized cord was immersed in an aqueous sodium hydroxide solution. The concentration and temperature of the sodium hydroxide aqueous solution and the treatment time are as shown in Table 2 below.

[Washing treatment]
Each sample after the hydroxylation treatment was washed with tap water in order to remove excess alkali adhering to the surface.

[Silane coupling agent treatment]
As a silane coupling agent, KBE-903 organosilane (manufactured by Shin-Etsu Chemical Co., Ltd., 3-aminopropyltriethoxysilane CAS No. 919-30-2) was used, and using this, a silane cup having a concentration of 2% by volume was used. An aqueous ring agent solution was prepared. A galvanized cord was immersed in a stainless steel container containing the silane coupling agent aqueous solution. The processing conditions are as described in Table 2 below.

[Heat treatment after silane coupling agent treatment]
About the galvanized cord after the silane coupling agent treatment, a coiled cord was hooked in an oven and subjected to heat treatment under the conditions shown in Table 2.

  Regarding the Zn cords A1, A2, A3 and A4 shown in Table 1, those subjected to the surface treatment described above were evaluated as adhesiveness by the pull-out test described later as Examples 1 to 4, respectively.

<Example 5>
The surface treatment was applied to Example 1 under the same conditions as in Example 1 except that the concentration of the NaOH aqueous solution in the hydroxylation treatment was changed to 0.01% by mass. This was used as Example 5 to evaluate adhesion by a pull-out test described later.

<Comparative Example 1>
The surface treatment was applied to Example 1 under the same conditions as in Example 1 except that the hydroxylation treatment was not performed. This was designated as Comparative Example 1, and the adhesion was evaluated by the pull-out test described below.

<Adhesion evaluation>
Each sample after the surface treatment was subjected to the following pull-out test to evaluate the adhesion between the surface-treated galvanized cord and the urethane resin.

[Pullout test]
Each sample after the surface treatment was subjected to extrusion coating with urethane resin (coating thickness 3 mm), and then a test sample was prepared by removing the coating portion so that the length of the coating portion was 10 mm (see FIG. 1). With respect to this sample, under the conditions shown in Table 3, the load (drawing force) necessary for drawing the galvanized cord was determined three times, and the average value is shown in Table 4.

  From the results shown in Table 4, it can be seen that a good pulling force approximately proportional to the surface area of each galvanized cord section is obtained, and that the surface treatment according to the present invention is effective.

Claims (13)

A hydroxylation treatment step for introducing a hydroxyl group into the surface of the galvanized substrate by bringing an alkaline aqueous solution into contact with the surface of the galvanized substrate;
A silane coupling agent that forms a hydrogen bond between a silanol group derived from the silane coupling agent and a hydroxyl group on the surface of the galvanized substrate by bringing a silane coupling agent aqueous solution into contact with the surface of the galvanized substrate after the hydroxylation treatment Processing steps, and
A process of forming a silane coupling agent film on the surface of the galvanized substrate through SiO bond formed by dehydration condensation reaction of the silanol group and the hydroxyl group by heating the galvanized substrate after the silane coupling agent treatment A method for surface treatment of a galvanized base material comprising: The surface treatment method for a galvanized substrate according to claim 1, wherein the aqueous alkali solution is an aqueous sodium hydroxide solution.   The surface treatment method for a galvanized substrate according to claim 1 or 2, wherein the silane coupling agent is an amino silane coupling agent.   The surface treatment method for a galvanized substrate according to any one of claims 1 to 3, wherein the galvanized substrate is a galvanized linear body.   The surface treatment method for a galvanized substrate according to any one of claims 1 to 4, wherein the galvanized substrate is a strand formed by twisting two or more galvanized linear bodies. Surface-treating the surface of the galvanized linear body using the surface treatment method for a galvanized substrate according to any one of claims 1 to 4 , and
Twist two or more surface-treated galvanized linear bodies to form a strand
A method of manufacturing a galvanized cord including By twisting two or more galvanized linear body to form a strand, and
The surface of the strand, be surface treated using the surface treatment method of the galvanized substrate according to any one of claims 1 to 5
A method of manufacturing a galvanized cord including A method for producing a galvanized cord comprising a plurality of sheath strands arranged around a core strand,
That by twisting two or more galvanized wire-like material to form the core strand, and has been surface treated with a surface treatment method of the galvanized substrate according to any one of claims 1 to 4 Twisting two or more galvanized wire bodies to form the sheath strand; and
Arranging a plurality of sheath strands around the core strand;
A method of manufacturing a galvanized cord including A method for producing a galvanized cord comprising a plurality of sheath strands arranged around a core strand,
By twisting two or more galvanized linear body to form the core strands,
By twisting two or more galvanized linear bodies forming the sheath strands,
The surface of the sheath strand, be surface treated by the surface treatment method of the galvanized substrate according to any one of claims 1 to 5, and
Arranging a plurality of the surface-treated sheath strands around the core strand
A method of manufacturing a galvanized cord including The said galvanized cord is a manufacturing method of the galvanized cord of any one of Claims 6-9 used as a reinforcing material of a transmission belt. A method for producing a transmission belt , comprising embedding a galvanized cord produced by the method for producing a galvanized cord according to any one of claims 6 to 9 in a belt body containing an elastomer material as a reinforcing material. The manufacturing method of the transmission belt of Claim 11 which contains a urethane resin as said elastomer material. The manufacturing method of the transmission belt of Claim 11 or 12 whose said transmission belt is a timing belt.