Suspension member, and method for manufacturing suspension member

Abstract

A suspension member (1) according to the present disclosure is provided with: a core member (2) which is formed of a fiber-reinforced plastic; and a cover layer (3) which is formed of a resin and covers the outer periphery of the core member (2). The fiber-reinforced plastic contains: reinforcing fibers; an epoxy compound which has an epoxy group; a curing agent; and a hydrazide compound.

Description

Technical Field

[0001] The present disclosure relates to a suspension member and a method for manufacturing the suspension member.

Background Art

[0002] In a conventional belt-shaped or rope-shaped suspension member using fibers, a load support portion is composed of a fiber-reinforced plastic made of a polymer matrix and fibers. Further, the outer periphery of the load support portion is covered with a coating layer such as polyurethane (see, for example, Patent Document 1: Japanese Patent No. 5713682).

[0003] When such a suspension member is applied to an elevator, the driving force from the elevator hoist is transmitted to the coating layer by the frictional force from the sheave of the hoist, and is transmitted to the load support portion through the coating layer to move the elevator car up and down. At this time, if the coating layer and the load support portion are not integrated, the driving force from the hoist may not be sufficiently transmitted to the load support portion, and the reliability of the elevator may decrease.

[0004] In response to such a problem, a suspension member in which an adhesion strengthening agent based on a melamine compound such as melamine phosphate, melamine pyrophosphate, or polymelamine phosphate is added to the coating layer is known (see, for example, Patent Document 2: International Publication No. WO2012 / 000169).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Even when a melamine-based adhesion enhancer is added as in Patent Document 2, in enhancing the adhesion to the load support portion, the adhesion between the load support portion and the coating layer is promoted by intermolecular forces and hydrogen bonds, and there are cases where the adhesion is insufficient.

[0007] In addition, when an additive such as the above-described adhesion enhancer is added to the coating layer, it bleeds out to the surface of the coating layer after aging, fluctuates the frictional force with the sheave of the hoisting machine, and affects the driving force transmission from the hoisting machine to the load support portion, which is one of the roles of the coating layer. There were cases where this happened.

[0008] Also, a means of applying an adhesive to the load support portion and covering the outer periphery thereof with a coating layer to increase the adhesive force can be considered, but this is not preferable because it increases the manufacturing process and complicates the process management.

[0009] Therefore, an object of the present disclosure is to provide a suspension member with improved adhesion between a core member made of fiber-reinforced plastic, which is a load support portion, and a coating layer without using an adhesive.

Means for Solving the Problems

[0010] The suspension member of the present disclosure includes a core member made of fiber-reinforced plastic and a coating layer that covers the outer periphery of the core member and is made of resin. The fiber-reinforced plastic includes reinforcing fibers, an epoxy compound having an epoxy group, a curing agent, and a hydrazide compound.

Effects of the Invention

[0011] According to the present disclosure, it is possible to provide a suspension member with improved adhesion between a core member made of fiber-reinforced plastic, which is a load support portion, and a coating layer without using an adhesive.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present disclosure will be described. In the drawings, dimensional relationships such as length, width, thickness, and depth are appropriately changed for clarity and simplification of the drawings, and do not represent actual dimensional relationships.

[0014] First, the characteristic principle of the present disclosure will be described. In the conventional technology, for example, the fiber-reinforced plastic (hereinafter sometimes abbreviated as FRP) that constitutes the core member 2 and the thermoplastic polyurethane elastomer (hereinafter sometimes abbreviated as TPU) that constitutes the coating layer 3 have low adhesion, so peeling occurs at the interface, and there is a concern that the driving force from the winch cannot be transmitted to the core member 2 which is the load support part. Therefore, usually, as shown in FIG. 16, the adhesion between the core member 2 (FRP) and the coating layer 3 (TPU) was improved by using an adhesive 21. However, there was a problem that a process of applying the adhesive 21 to the surface of the core member 2 was required, increasing the manufacturing process.

[0015] In contrast, in the present disclosure, as shown in FIG. 1, first, a hydrazide compound is blended into the FRP that constitutes the core member 2, and the FRP is cured at a first temperature (T1). Next, the adhesive coating process that was conventionally required is omitted, and a coating layer 3 made of TPU or the like is formed on the outer periphery of the FRP (core member 2) by extrusion molding at a second temperature (T2). Here, at the temperature T1 (for example, 120 °C) during the thermosetting of the FRP (core member 2), the hydrazide compound is inactive and does not react with the epoxy compound. On the other hand, at the extrusion molding temperature T2 (for example, 200 °C) when forming the coating layer, the hydrazide compound is activated and chemically bonds with the epoxy groups remaining in the FRP, improving the adhesion at the interface between the FRP (core member) and the coating layer.

[0016] Embodiment 1. (Suspension member) FIGS. 2 to 8 are schematic cross-sectional views showing an example of the suspension member of Embodiment 1. The suspension member of Embodiment 1 includes a core member 2 which is a load support part inside, and a coating layer 3 that covers the outer periphery of the core member 2.

[0017] The suspension member 1 shown in FIG. 2 includes a core member 2 having a rectangular cross-sectional shape that is wider in the width direction than in the thickness direction, and a coating layer 3 that covers the outer periphery of the core member 2. The suspension member 1 also has a rectangular cross-sectional shape.

[0018] The suspension member shown in Fig. 3 has a plurality of core members 2 having a rectangular cross-sectional shape. The plurality of core members 2 are arranged side by side in the width direction of the suspension member 1, and the outer peripheries of these core members 2 are covered with a covering layer 3. The suspension member 1 also has a rectangular cross-sectional shape.

[0019] In the suspension member 1 shown in Fig. 4, a plurality of core members 2 are arranged side by side in the thickness direction of the suspension member 1, and the outer peripheries of these core members 2 are covered with a covering layer 3.

[0020] The suspension member shown in Fig. 5 includes a core member 2 having a square cross-sectional shape with equal lengths in the thickness direction and the width direction, and the outer periphery of the core member 2 is covered with a covering layer 3. The suspension member 1 also has a square cross-sectional shape.

[0021] The suspension member shown in Fig. 6 includes a core member 2 having a circular cross-sectional shape, and the outer periphery of the core member 2 is covered with a covering layer 3. The suspension member 1 also has a circular cross-sectional shape.

[0022] The suspension member shown in Fig. 7 has a rectangular cross-sectional shape and includes a plurality of core members 2 having a circular cross-sectional shape. The plurality of core members 2 are arranged side by side in the width direction of the suspension member 1, and the outer peripheries of these core members 2 are covered with a covering layer 3.

[0023] The suspension member shown in Fig. 8 has a plurality of core members 2 having a circular cross-sectional shape. The plurality of core members 2 are arranged bundled, and the outer peripheries of the plurality of core members 2 are covered with a covering layer 3. The suspension member 1 also has a circular cross-sectional shape.

[0024] Note that the suspension members shown in Figs. 2 to 8 are examples of the suspension members included in Embodiment 1, and the suspension members of Embodiment 1 are not limited to these.

[0025] The suspension member of Embodiment 1 is, for example, a long member, and preferably a continuous body having substantially the same cross-sectional shape with respect to the longitudinal direction. The overall shape of the suspension member of Embodiment 1 may be, for example, belt-shaped or rope-shaped. The core member 2 is arranged, for example, parallel to the same direction as the longitudinal direction of the suspension member 1.

[0026] The core member 2 is, for example, a long member similar to the suspension member, and preferably a continuous body having substantially the same cross-sectional shape with respect to the longitudinal direction. The overall shape of the core member 2 may be, for example, belt-shaped or rope-shaped (fibrous). Note that, for example, the fibrous core member 2 may form a long aggregate such as a woven fabric or a braided cord formed by twisting or braiding.

[0027] The core member 2 is made of a fiber-reinforced plastic. The fiber-reinforced plastic includes reinforcing fibers, an epoxy compound having an epoxy group, a curing agent, and a hydrazide compound. Here, the description of including an epoxy compound having an epoxy group, a curing agent, and a hydrazide compound also has the meaning of including the functional groups derived from each compound as constituent units of the polymer.

[0028] FIG. 9 is a conceptual diagram showing an enlarged cross-section of an example of the core member of the suspension member of Embodiment 1. As shown in FIG. 9, the core member 2 is made of a fiber-reinforced plastic composed of reinforcing fibers 4 and a resin part 5.

[0029] The material of the reinforcing fibers 4 is not particularly limited, but it is preferable that the reinforcing fibers are lightweight and have high strength and elastic modulus. As the reinforcing fibers, for example, one type selected from carbon fibers, glass fibers, aramid fibers, polyarylate fibers, polyparaphenylene benzobisoxazole fibers, etc., or fibers formed by blending two or more types can be used.

[0030] The resin part 5 contains an epoxy compound having an epoxy group, a curing agent, and a hydrazide compound. For example, the resin part 5 contains, as constituent units of the polymer constituting the resin part 5, functional groups derived from an epoxy compound having an epoxy group, a curing agent, and a hydrazide compound as constituent units of the polymer.

[0031] The resin part 5 is preferably composed of a cured product (epoxy resin) of a resin composition containing an epoxy compound, a curing agent, and a hydrazide compound.

[0032] In addition to the above epoxy resin, the resin part 5 may contain a resin other than the above epoxy resin. Examples of the resin other than the above epoxy resin include thermosetting resins obtained by adding a curing agent to polyurethane, unsaturated polyester, vinyl ester, phenol, etc., thermoplastic resins such as polyurethane, polyamide 6 (PA6), polyamide 12 (PA12), polyamide 66 (PA66), and epoxy resins not containing a hydrazide compound. The resin constituting the resin part 5 may contain additives such as a flame retardant.

[0033] The hydrazide compound is not particularly limited as long as it is a compound having a hydrazide group (-NHNH 2 ). Examples of the hydrazide compound include adipic acid dihydrazide, sebacic acid dihydrazide (SDH), dodecanedioic dihydrazide, isophthalic acid dihydrazide (IDH), salicylic acid hydrazide, etc. As the hydrazide compound, one or a mixture of two or more selected from these can be used.

[0034] The hydrazide group of the hydrazide compound is a latent curing agent that is not activated at low temperatures and is activated at a certain specific temperature (activation temperature) or higher to react with an epoxy group or the like. The above activation temperature varies depending on the type of hydrazide compound. For example, for isophthalic acid dihydrazide, it is 140°C.

[0035] The addition amount of the hydrazide compound is not particularly limited, but is preferably 0.01% by mass to 70% by mass, more preferably 0.1% by mass to 50% by mass, based on the total amount of the resin part 5 (the resin composition serving as the raw material of the resin part 5). When the addition amount of the hydrazide compound is 0.01% by mass or less, since the amount of the hydrazide compound is too small, the adhesion between the core member and the coating layer may not be sufficiently improved. Further, when the addition amount of the hydrazide compound is 70% by mass or more, it becomes difficult to mix the hydrazide compound into the resin composition to be a fiber-reinforced plastic due to reasons such as thickening.

[0036] As the curing agent, various compounds known as curing agents for epoxy compounds can be used. Examples of the curing agent include amine compounds (amine-based curing agents).

[0037] The resin constituting the coating layer 3 is not particularly limited, and examples thereof include thermoplastic polyurethane elastomers, thermoplastic polystyrene elastomers, thermoplastic vinyl chloride elastomers, thermoplastic polyester elastomers, thermoplastic polyamide elastomers, thermoplastic polybutadiene elastomers, and the like. From the viewpoints of the frictional force with the sheave of the hoisting machine and the abrasion resistance, a thermoplastic polyurethane elastomer can be preferably used as the resin material constituting the coating layer 3.

[0038] Examples of the thermoplastic polyurethane elastomer include ether-based thermoplastic polyurethane elastomers and carbonate-based thermoplastic polyurethane elastomers. These are materials that are difficult to hydrolyze in a high-temperature and high-humidity environment and can be preferably used.

[0039] In addition to these, examples of the resin constituting the coating layer 3 include olefin-based elastomers, styrene-based elastomers, vinyl chloride-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, etc., and one or a mixture of two or more of these can be used. Further, the resin material constituting the coating layer 3 may contain additives such as flame retardants, crosslinking agents, colorants, lubricants, etc.

[0040] In particular, when the resin material constituting the coating layer 3 is a material (such as thermoplastic polyurethane elastomer) that does not sufficiently obtain adhesion to the fiber-reinforced plastic constituting the core member 2 as it is, the effect obtained by the suspension member of the present disclosure is useful.

[0041] (Manufacturing method of suspension member) Next, the manufacturing method of the suspension member of Embodiment 1 will be described with reference to the flow of an example of the manufacturing method of the suspension member of Embodiment 1 shown in FIG. 10.

[0042] First, the first heating step is carried out. In the first heating step, the resin composition containing an epoxy compound having an epoxy group, a curing agent, and a hydrazide compound having a hydrazide group is heated at the first temperature (T1) in a state where it is in contact with reinforcing fibers, and the epoxy compound and the curing agent are reacted to form a core member.

[0043] Specifically, referring to FIG. 10, first, a hydrazide compound is mixed with a base material composed of an epoxy compound (a compound having an epoxy group) and a curing agent to prepare a resin composition as a raw material for the core member. Next, the obtained resin composition is impregnated into reinforcing fibers (such as a web made of reinforcing fibers) arranged in a mold. Next, the resin composition impregnated into the reinforcing fibers is heated at the first temperature (T1) to form at least one core member.

[0044] Here, the first temperature (T1) is a temperature at which the hydrazide group of the hydrazide compound is not activated (a temperature lower than the temperature at which the hydrazide compound begins to be activated). Therefore, in the first heating step, the epoxy group of the epoxy compound in the resin composition reacts with the curing agent (such as an amine compound), and the hydrazide compound, which has a slower reaction rate (lower activity) than the curing agent, remains unreacted in the resin composition. In order for a large amount of the unreacted hydrazide compound to remain in the resin composition, the first temperature (T1) is preferably 300 °C or lower, more preferably 200 °C or lower, and most preferably 180 °C or lower. Note that at such a temperature, it is expected that some epoxy compound remains in the core member after the first heating step. This unreacted epoxy compound can react with the hydrazide compound in the second heating step described later.

[0045] If T1 is a temperature at which the hydrazide compound is activated (for example, 300 °C or higher), the hydrazide compound reacts with the epoxy group in the resin composition and is consumed during the first heating step (when forming the core member). In this case, it is possible to react with the epoxy compound in the resin composition by heating at the second temperature (T2) in the second heating step (when forming the coating layer) described later, and since there is no hydrazide compound that interacts with the resin constituting the coating layer, the effect of improving the adhesion between the core member and the coating layer is not exhibited.

[0046] Further, in order to cure the resin composition to form the core member, the first temperature (T1) is preferably equal to or higher than the curing temperature (polymerization initiation temperature) of the composition containing the epoxy compound and the curing agent. From such a viewpoint, the first temperature (T1) is preferably 80 °C or higher, more preferably 100 °C or higher, and most preferably 120 °C or higher.

[0047] If T1 is lower than the curing temperature (for example, 80 °C) of the composition containing the epoxy compound and the curing agent, the epoxy compound and the curing agent in the resin composition cannot react sufficiently, the core member cannot be formed, and the suspension member cannot be manufactured.

[0048] Next, a second heating step is carried out. In the second heating step, the resin composition is heated at a second temperature (T2) which is higher than the first temperature, in a state where the coating material composition which is the raw material of the resin constituting the coating layer is arranged to cover the outer periphery of the core member, so that the hydrazide group of the hydrazide compound reacts with the epoxy compound contained in the fiber reinforced plastic constituting the core member.

[0049] Specifically, referring to FIG. 10, by a method such as extrusion molding, a resin (such as a thermoplastic polyurethane elastomer) which is the material of the coating layer is heated and melted at the second temperature (T2), and a coating layer is formed on the outer periphery of one or a plurality of core members.

[0050] In such a second heating step, heat at the second temperature (T2) is also applied to the core member, and the unreacted hydrazide compound in the core member chemically reacts with the epoxy compound remaining unreacted in the core member to form a chemical bond. Further, the hydrazide compound also interacts with the coating layer by hydrogen bonding or intermolecular forces or the like. Thereby, the adhesion between the core member and the coating layer is improved.

[0051] The second temperature (T2) is the temperature at which the hydrazide group of the hydrazide compound is activated. The second temperature (T2) is preferably 140°C or higher and 400°C or lower. When T2 is lower than 140°C, the hydrazide compound is not activated and it is difficult to react with the epoxy compound in the resin composition, so there is a possibility that the improvement in adhesion and curing cannot be obtained. On the other hand, when T2 is higher than 400°C, there is a concern that the fiber reinforced plastic (core member) or the resin constituting the coating layer may deteriorate due to thermal decomposition. Note that T1 and T2 are appropriately adjusted according to the types, compositions, etc. of the materials constituting the core member and the coating layer.

[0052] The suspension member of Embodiment 1 described above is excellent in the adhesion (adhesive strength) between the core member which is the load support part and the coating layer. The suspension member of Embodiment 1 can be applied, for example, as a suspension member (such as an elevator rope) for an elevator.

[0053] Embodiment 2. (Suspension member) Figs. 11 to 14 are schematic cross-sectional views showing an example of the suspension member of Embodiment 2. The suspension member 1 of Embodiment 2 includes a plurality of core members 2 inside, and a part or all of the plurality of core members 2 are twisted or braided. The outer periphery of the plurality of twisted or braided core members 2 is covered with a coating layer 3. Since other points are the same as those in Embodiment 1, overlapping explanations are omitted.

[0054] The suspension member shown in Fig. 11 has a plurality of core members 2 having a circular cross-sectional shape, and the plurality of core members 2 are twisted together. The outer periphery of the twisted plurality of core members 2 is covered with a coating layer. The suspension member 1 also has a circular cross-sectional shape.

[0055] The suspension member 1 shown in Fig. 12 has a rectangular cross-sectional shape. In the suspension member 1, a plurality of twisted core members 2 are arranged side by side in the width direction of the suspension member 1.

[0056] The suspension member 1 shown in Fig. 13 has a circular cross-sectional shape. The suspension member 1 includes a plurality of core members 2a on the outer peripheral side and a core member 2b on the center side inside, and the plurality of core members 2a on the outer peripheral side are twisted around the outer periphery of the core member 2b on the center side.

[0057] The suspension member shown in Fig. 14 has a rectangular cross-sectional shape. In this suspension member 1, a plurality of twisted core members 2a, 2b, similar to those in Fig. 13, are arranged side by side in the width direction of the suspension member 1.

[0058] The suspension members shown in Figs. 11 to 14 are examples of the suspension members included in Embodiment 2, and the suspension members of Embodiment 2 are not limited to these.

[0059] In the suspension member of Embodiment 2, at least some of the plurality of core members are arranged as a long aggregate such as a fabric or a braided cord formed by twisting or braiding a plurality of fibrous core members, for example. Some other core members may be arranged without being twisted or braided.

[0060] In the suspension member of Embodiment 2, for example, a long aggregate formed by twisting or braiding a plurality of core members is arranged such that the longitudinal direction of the aggregate is parallel to the longitudinal direction of the suspension member.

[0061] (Manufacturing method of suspension member) Next, the manufacturing method of the suspension member of Embodiment 2 of the present disclosure will be described with reference to the flow of an example of the manufacturing method of the suspension member of Embodiment 2 shown in FIG. 15.

[0062] Up to the process of obtaining the core members (first heating process), it is the same as the manufacturing method of the suspension member of Embodiment 1. A plurality of core members obtained in the first heating process are twisted together. Next, a coating layer is formed on the outer periphery of the plurality of twisted core members by the same method as in Embodiment 1.

[0063] The suspension member of Embodiment 2 includes a plurality of core members, and some or all of the plurality of core members are twisted or braided, so it has the characteristic of being more bendable compared to the suspension member of Embodiment 1.

[0064] On the other hand, in the suspension member of Embodiment 2, since some or all of the plurality of core members are twisted, the cross-sectional area of the core members that can be included per cross-section of the suspension member is smaller compared to the suspension member of Embodiment 1. Therefore, for example, when trying to obtain the same strength as the suspension member of Embodiment 1 in the suspension member of Embodiment 2, usually, the overall cross-sectional area of the suspension member of Embodiment 2 is larger than that of Embodiment 1. Thus, the suspension members of Embodiment 1 and Embodiment 2 can be selected according to the intended application, considering their respective advantages and disadvantages.

Examples

[0065] The present disclosure will be described in more detail with the following examples, but the present disclosure is not limited to these examples.

[0066] (Example 1) As shown in Table 1, an epoxy compound (product number EP-4100E manufactured by ADEKA) as the base material (main component), an amine-based curing agent (product number HN-2000 manufactured by Hitachi Chemical), and an imidazole-based curing accelerator (product number 1B2MZ manufactured by Shikoku Chemicals) were mixed. To the resulting mixture, isophthalic acid dihydrazide (IDH), which is a hydrazide compound, was further mixed to prepare a resin composition (see Figure 10). Note that isophthalic acid dihydrazide was added at a ratio of 3% by mass based on the total amount of the resin composition.

[0067] This resin composition was impregnated into polyacrylonitrile (PAN)-based carbon fibers and cured at 120 °C (T1) to obtain a core member made of continuous fiber-reinforced plastic with a rectangular cross-section having a width of 40 mm and a thickness of 2 mm.

[0068] Thereafter, a coating layer with a thickness of 1 mm covering the outer periphery of the obtained core member was formed by extrusion molding at 200 °C (T2) using an ether-based thermoplastic polyurethane elastomer to obtain the suspension member of Example 1.

[0069] (Example 2) In Example 2, sebacic acid dihydrazide (SDH) was used as the hydrazide compound. Otherwise, in the same manner as in Example 1, the suspension member of Example 2 was obtained.

[0070] (Comparative Example 1) In Comparative Example 1, no hydrazide compound was added. Otherwise, in the same manner as in Example 1, the suspension member of Comparative Example 1 was obtained.

[0071] <Evaluation Test> For the suspension members obtained in Examples 1 and 2 and Comparative Example 1, a peel test was conducted based on JIS K 6854-2 to evaluate the adhesion (adhesive strength) between the core member and the coating layer. The peel strength (adhesive strength) was expressed as the value (N / m) obtained by dividing the obtained test force (N) by the width (m) of the test piece. Also, the peel test was carried out with the test displacement from 0 mm to 80 mm, and the average value of the peel strength from the test displacement of 20 mm to 60 mm was taken as the peel strength.

[0072]

Table 1

[0073] From the results shown in Table 1, it can be seen that in the suspension members of Examples 1 and 2 in which the fiber-reinforced plastic constituting the core member contains a hydrazide compound, the adhesion (adhesive strength) between the core member and the coating layer is significantly superior compared to Comparative Example 1 in which the fiber-reinforced plastic does not contain a hydrazide compound.

[0074] The embodiments and examples disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present disclosure is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0075] 1 Suspension member, 2, 2a, 2b Core member, 21 Adhesive, 3 Coating layer, 4 Reinforcing fiber, 5 Resin part.

Claims

1. A suspension member comprising a core member made of a fiber-reinforced plastic and a coating layer made of a resin that covers the outer periphery of the core member, wherein the fiber-reinforced plastic contains reinforcing fibers, an epoxy compound having an epoxy group, a curing agent, and a hydrazide compound.

2. The suspension member according to claim 1, wherein the resin constituting the coating layer is a thermoplastic polyurethane elastomer.

3. The suspension member according to claim 1 or 2, wherein the curing agent is an amine compound.

4. A method for manufacturing the suspension member according to any one of claims 1 to 3, comprising: a first heating step of forming the core member by reacting the epoxy compound and the curing agent by heating the resin composition containing an epoxy compound having an epoxy group, a curing agent, and a hydrazide compound having a hydrazide group in a state where the resin composition is in contact with reinforcing fibers at a first temperature; a second heating step of reacting the hydrazide group of the hydrazide compound with the epoxy compound contained in the fiber-reinforced plastic constituting the core member by heating the resin composition at a second temperature, which is higher than the first temperature, in a state where a coating material composition, which is a raw material of the resin constituting the coating layer, is disposed so as to cover the outer periphery of the core member.

5. The first temperature is a temperature at which the hydrazide group of the hydrazide compound is not activated, The second temperature is a temperature at which the hydrazide group of the hydrazide compound is activated. The method for manufacturing a suspension member according to claim 4.

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