JP2023074569A - Fastening member, and fastener comprising the same and resin mating member - Google Patents

Abstract

To provide a fastening member capable of improving residual torque after fastening when fastening a member to be fastened and a resin mating member with the fastening member, and a fastener comprising the fastening member and the resin mating member.SOLUTION: A fastening member is screwed into a resin mating member in order to fasten a member to be fastened and the resin mating member, and the fastening member comprises a body having a thread on its outer periphery, and a resin layer provided on the thread. The resin layer comprises a cured product of a curable resin composition containing a curable resin and a filler, where particles constituting the filler include particles having a hardness different from the hardness of the mating member, and an average particle size of the filler is less than or equal to a thickness of the resin layer.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening member including a body having threads on its outer periphery and a resin layer provided on the threads. The present invention also relates to a fastener including the fastening member and a resin mating member.

Methods for fastening a metal mating member and a member to be fastened include, for example, a method in which a metal bolt is passed through and the two are fastened from the opposite side with a metal nut; Metal fastening is known, for example, a method in which a male screw made of metal is passed through a member to be fastened and tightened into the female threaded portion of the member.

With respect to the above metal fastening, Patent Document 1 discloses a high-friction paint that is used for high-strength bolted joints of the friction-joining method and can have a slip coefficient of 0.45 or more. This high friction paint is mainly composed of an epoxy resin and a pigment containing zinc dust with a volume average particle size of 1 to 40 μm and an aggregate with a volume average particle size of 3 to 10 μm. It is coated on the steel material with a film thickness of 50 to 150 μm.

Further, in Patent Document 2, even when used in a high temperature and corrosive environment (specifically, in an environment in a chemical plant), it has excellent corrosion resistance and can suppress the occurrence of seizure. A bolt and nut are disclosed. The bolt and nut have a difference of 150 or more between the Vickers hardness of the bolt and the Vickers hardness of the nut at the portion where they contact each other.

In addition to the metal fastening described above, resin fastening, for example, a method of fastening a member to be fastened to a mating member by tightening a resin male screw into a female thread provided on the resin mating member is also known.

Japanese Patent Application Laid-Open No. 2004-26972 JP 2018-141490 A

However, unlike the metal fastening, the resin fastening sometimes had a residual torque of zero after the endurance test under temperature and input load. One of the causes of this problem is the property of resin to creep (plastic deformation that appears over time under constant stress). When this creep phenomenon occurs, it becomes difficult to maintain the balance between the axial force and the bearing surface (the contact surface between the member to be fastened and the male screw) in metal fastening with resin fastening. That is, the resin fastening that has been performed so far has low reliability in terms of torque maintenance after fastening.

Resin fastening and metal fastening are fastening methods for different fastening objects, and by applying the inventions disclosed in Patent Documents 1 and 2 regarding metal fastening, the problem of residual torque that occurs only in resin fastening can be solved. It is difficult to resolve.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a fastening member capable of improving residual torque after fastening when a member to be fastened and a mating member made of resin are fastened by the fastening member; An object of the present invention is to provide a fastener including the fastening member and a mating member made of resin.

In order to achieve the above object, a fastening member according to claim 1 is provided,
A fastening member to be screwed into the resin mating member for fastening the member to be fastened to the resin mating member, comprising a main body having a thread on its outer periphery and a resin layer provided on the thread,
The resin layer comprises a cured product of a curable resin composition containing a curable resin and a filler,
The particles constituting the filler include particles having a hardness different from the hardness of the mating member,
The average particle size of the filler is equal to or smaller than the thickness of the resin layer.

Another aspect of the fastening member according to the present invention is characterized in that the particles constituting the filler are particles having hardness higher than that of the mating member.

Another aspect of the fastening member according to the present invention is characterized in that the filler has an average particle size of 0.1 to 20 μm.

Another aspect of the fastening member according to the present invention is that the filler is zinc oxide, and the zinc oxide content is 10% by mass to 40% by mass with respect to 100% by mass of the curable resin composition. It is characterized by

A fastener comprising the fastening member and the resin mating member is for fastening a member to be fastened disposed between the fastening member and the resin mating member to the mating member. It is characterized by

According to the present invention, when a member to be fastened and a mating member made of resin are fastened together by a fastening member, the frictional force at the portion where the fastening member and the mating member come into contact is improved, so that after fastening with the resin, the frictional force is improved. Residual torque can be improved.

In addition, such an improvement in residual torque expands the range of application of resin fastening instead of metal fastening, making it possible to reduce the weight compared to the weight of members used for metal fastening.

Furthermore, since it is possible to avoid using a metal member that is used to improve residual torque in resin fastening, it is possible to avoid combining different members of resin and metal and improve recyclability.

4 is a graph showing the results of a basic evaluation test on the relationship between the film thickness of a resin layer and the coefficient of friction.

A fastener according to an embodiment of the present invention is a fastening member and a resin mating member (for example, a metal member or a resin member provided with a resin female thread, or a resin member (having no female thread)). Prepare. The fastening member includes a body (for example, a male screw) having a thread on its outer periphery and a resin layer provided on the thread. With this fastener, a member to be fastened arranged between the fastening member and the resin-made mating member can be fastened to the mating member. Specifically, the object to be fastened can be fastened to the resin-made mating member by the fastening force between the fastening member and the resin-made mating member. A member made of resin or metal can be used as the member to be fastened.

The fastening member and the resin-made mating member can be fastened by using the fastening member as a tapping screw and screwing the fastening member into the resin-made member (without a female thread) as the resin-made mating member, or by screwing the fastening member into a metal A metal member (with a resin female thread) or a resin member as a mating member made of resin by providing a female screw made of resin on a made member or a resin member and screwing the female thread and a fastening member together. This can be done by, for example, screwing the fastening member into the joint.

The body of the fastening member having threads on its outer circumference can be made of resin or metal. The mating member is made of resin.

The resin used for the resin body can be, for example, a known resin used as a material for male screws. The metal used for the metal body can be, for example, any known metal used as material for external threads.

The resin used for the mating member made of resin is a known resin used as a material for internal threads, such as polyamide resin (e.g., nylon 6 or nylon 66) or engineering plastic (e.g., polybutylene terephthalate resin (PBT ) or polyethylene terephthalate resin (PET)).

The resin layer can be directly provided on the surface of the main body of the fastening member, or can be provided on the fastening member via another layer. The resin layer can also be provided only at locations where the fastening member and the resin-made counterpart member come into contact when they are fastened together (for example, only on the threads). By providing the resin layer, it is possible to improve the coefficient of friction between the fastening member and the mating member made of resin, thereby improving the residual torque.

The thickness (film thickness) of the resin layer is preferably the same as or larger than the average particle size of the filler. This can prevent the filler from dropping out of the resin layer. Regarding the thickness of the resin layer, the lower limit is preferably 0.1 μm or more, more preferably 0.5 μm or more, and more preferably 1 μm or more, and the upper limit is preferably 30 μm or less, more preferably 20 μm or less. More preferably, it is 10 μm or less, and these numerical values can be arbitrarily combined to form the thickness range of the resin layer (for example, 0.1 to 30 μm).

The resin layer can be obtained from a curable resin composition containing a curable resin and a filler. The curable resin serves as a binder for holding the filler on the main body of the fastening member. The filler has the role of increasing the coefficient of friction between the fastening member and the mating member. It is preferable to use a filler that has an anchoring effect on the curable resin.

The curable resin composition may optionally contain other additives (eg, dyes and/or thickeners).

In order to reduce the viscosity of the curable resin composition and make it easy to handle, the curable resin composition is mixed with a solvent (for example, an organic solvent (specifically, a mixture of methyl ethyl ketone, xylene, and propylene glycol monomethyl ether acetate)). ) can be used to handle the curable resin composition.

The curable resin composition uses a known stirrer (e.g., propeller stirrer or homogenizer) to determine the temperature, stirring rotation speed, and stirring time according to the common technical knowledge of those skilled in the art, and the curable resin, Fillers and optional ingredients can be mixed.

For example, in the case of a curable resin composition dissolved in an organic solvent, using a known stirrer (eg, propeller stirrer or homogenizer), 0 ~ 40 ° C., rotation speed 500 ~ 8000 rpm, 5 ~ It can be obtained by dissolving a curable resin composition containing a curable resin, a filler and optional components in an organic solvent under stirring conditions for 60 minutes. The mixing process includes, for example, a kneading process and a milling process.

As the curable resin, any curable resin can be used as long as it can be mixed with a filler and can provide a degree of hardness that does not break the resin layer when the fastening member is fastened to the mating member. There are no particular restrictions, and thermosetting resins or photo-setting resins, particularly preferably thermosetting resins, can be used. Thermosetting resins include known epoxy resins (e.g., modified epoxy resins or bisphenol A solid epoxy resins), known phenol resins (e.g., modified phenol resins), or known epoxy resins and known phenol resins. A combination of

In the case of a combination of a known epoxy resin and a known phenolic resin, the ratio of epoxy resin to phenolic resin is preferably 1-2:1, more preferably 1.5:1. Moreover, the phenolic resin used in this combination has a role of increasing the hardness of the resin layer.

A known photocurable resin can be used as the photocurable resin.

As fillers, organic fillers and/or inorganic fillers, preferably inorganic fillers, can be used. Examples of materials that can be used for the organic filler include (meth)acrylic resins, polyamide resins, and polyolefin resins. Materials for the inorganic filler include, for example, metal compounds (zinc oxide (having a hardness of 4 to 5 in the case of Mohs' hardness), zinc sulfide (having a hardness of 3.5 to 4 in the case of Mohs' hardness), Antimony trioxide (such as having a hardness of 2-2.5 on the Mohs scale), or combinations thereof) can be used. Zinc oxide is particularly preferred because it is sufficiently harder than the mating member and a sufficient anchoring effect can be obtained.

The content of the filler is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 30% by mass or more, relative to 100% by mass of the curable resin composition. The upper limit is preferably 45% by mass or less, more preferably 40% by mass or less, and these numerical values can be arbitrarily combined to make the thickness range of the resin layer (for example, 10 to 45 mass% %). By adjusting the content to such a value, a sufficiently high coefficient of friction can be obtained and sufficient coating film strength can be maintained.

The content of the curable resin is preferably 55% by mass or more, more preferably 60% by mass or more, and the upper limit is preferably 90% by mass with respect to 100% by mass of the curable resin composition. %, more preferably 80 μm mass % or less, and even more preferably 70 mass % or less, and these numerical values can be arbitrarily combined to make the thickness range of the resin layer (for example, 55 to 90 mass % %).

A known colored (eg, black) dye can be used as the dye. The dye has a role of easily determining whether or not the resin layer is provided on the fastening member.
A known thickener can be used as the thickener. The thickener has the role of improving the paintability of the curable resin composition onto the fastening member.

Formation of the resin layer on the fastening member can be performed by the following method.
First, a curable resin composition (or a curable resin composition dissolved in an organic solvent) is applied to the body of the fastening member by a known coating method (e.g., spray coating method or barrel coating method). apply. Thereafter, the applied curable resin composition is usually dried at an ambient temperature of 180 to 200° C. for 30 to 60 minutes to obtain (form) a resin layer (cured product of the curable resin composition). can.

The curable resin composition can also be applied to the main body of the fastening member simply by degreasing the main body of the fastening member.

In addition, the curable resin composition can also be applied to the main body (especially, metal main body) of the fastening member after chemical treatment (for example, treatment using a chemical such as zinc phosphate). . The curable resin composition can also be applied to the main body of the fastening member after plating the main body (particularly, the metal main body) of the fastening member.

Particles constituting the filler include particles having a hardness different from that of the mating member. Preferably, the particles constituting the filler are particles having hardness higher than that of the mating member.

Here, for example, Mohs hardness or Vickers hardness can be used as the hardness index. The Mohs hardness and Vickers hardness can be determined using known measuring methods. For example, in the case of measurement of Mohs hardness, it can be determined by whether or not it can be scratched by a general Mohs standard mineral. Specifically, a standard mineral and a sample material can be rubbed and hardness can be measured based on the presence or absence of scratches. Examples of (standard) minerals having a Mohs hardness of 1 to 10 include talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum, and diamond.

More preferably, the particles constituting the filler are particles having a Mohs hardness higher by one rank or more than the Mohs hardness of the mating member. By increasing the difference between the Mohs hardness of the particles constituting the filler and the Mohs hardness of the mating member by one rank or more, sufficient fastening force can be obtained between the particles constituting the filler and the mating member. As for the difference between the Mohs hardness of the particles constituting the filler and the Mohs hardness of the mating member, a sufficient fastening force can be obtained if the difference is 1 or more, so the upper limit is not particularly limited.

The hardness of the main body, the resin layer (particularly filler), and the mating member in the fastening member preferably satisfies the following relationship: (main part of the fastening member≧) resin layer (particularly filler)>mating member.

A fastening member having a specific range of hardness (e.g., Mohs hardness or Vickers hardness), a mating member having a specific range of hardness (e.g., Mohs hardness or Vickers hardness), and a specific range of hardness (e.g., Mohs hardness or Vickers hardness) Vickers hardness) can be obtained according to the common technical knowledge of those skilled in the art.

The average particle size of the filler is the same as or smaller than the thickness of the resin layer. This can prevent the filler from coming off. Specifically, the lower limit of the average particle size of the filler is preferably 0.1 μm or more, more preferably 0.5 μm or more, and the upper limit is preferably 20 μm or less, more preferably It is 10 μm or less, and even more preferably 5 μm or less, and any combination of these values can be used as the average particle size range of the filler (for example, 0.1 to 20 μm).
The average particle size means the particle size at an integrated value of 50% in the particle size distribution determined by the laser diffraction/scattering method.

Fasteners according to the present invention are used in automobiles, specifically parts used in parts where vibrations are applied during driving (for example, parts for fixing attachments (such as radar) mounted on bumpers), and It can be used for parts that are used in parts that are subjected to impacts while the vehicle is stationary (eg, doors, trunks, and rear gates).

EXAMPLES The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples.

[Basic evaluation test for the relationship between the thickness of the resin layer and the coefficient of friction]
A basic evaluation test for the relationship between the thickness of the resin layer and the coefficient of friction was conducted by the following method.

(Preparation of test piece)
A SPCC (Steel Plate Cold Commercial) plate was plated with MFZn5C. Filler (manufactured by Hakusui Tech Co., Ltd.; 2 types of zinc oxide; Mohs hardness 4 to 5; average particle size 1.0 μm) 37% by mass and epoxy resin (manufactured by Arakawa Chemical Industries, Ltd.; product name Arakid 9203N) as a binder 63% by mass A mixture (curable resin composition: 100% by mass) is dissolved in an organic solvent (specifically, [methyl ethyl ketone, xylene, propylene glycol monomethyl ether acetate mixture]) (curable resin composition: organic solvent = 1:1), and these were coated on the plating so that the thickness of the resin layer was 0 µm (no coating), 2 µm, 5 µm, and 10 µm. The dissolution of the curable resin composition in the organic solvent was carried out using a stirring device (LAB-STIRRER LR-51B manufactured by Yamato Scientific Co., Ltd.) at 25° C. for 30 minutes at a rotation speed of about 700 rpm.

After the above coating, leave them in an oven at 200 ° C. (i.e., ambient temperature 200 ° C.) for 30 minutes to thermally cure the curable resin composition to obtain various film thicknesses (0 μm, 2 μm, 5 μm, 10 μm). A test piece having a resin layer of

(Evaluation method)
Evaluation (specifically, friction coefficient measurement) is performed by repeatedly sliding test pieces with various film thicknesses using a reciprocating sliding tester (HEIDON-14 special; manufactured by Shinto Kagaku Co., Ltd.). It was done by

Specific test conditions are as follows.
Material to contact the test piece: 10 mm diameter nylon sphere;
Load: 9.8N (1,000gf);
Speed: 3,000mm/min;
Stroke: 10 mm; and Evaluation method: The coefficient of friction (μs, μd) was measured after the 10th sliding. Measurement was performed three times, and the average value was taken as the coefficient of friction.

(Test results)
The test results are shown in FIG. In the case of having a resin layer (thickness: 2 μm, 5 μm, and 10 μm), the static friction coefficient and the dynamic friction coefficient increased compared to the case of not having a resin layer (thickness: 0 μm). At film thicknesses of 2 μm, 5 μm, and 10 μm, almost no change in the coefficient of friction was observed.

[Results of test on residual torque in resin fastening]
(Preparation of curable resin composition)
According to the formulation shown in Table 1 below, an epoxy resin (Arakawa Chemical Industry Co., Ltd. Co., Ltd.; product name Arakid 9203N) 63% by mass and filler (manufactured by Haku Sui Tech Co., Ltd.; zinc oxide type 2; Mohs hardness 4 to 5; average particle size 1.0 μm) 37% by mass (curable resin composition : 100% by mass) was dissolved in an organic solvent (specifically, a mixture of methyl ethyl ketone, xylene, and propylene glycol monomethyl ether acetate) (curable resin composition: organic solvent = 1:1).

(Creation of fastening members)
A resin male screw (screw grommet) manufactured by NIFCO was used as the main body of the fastening member. A metal male screw of M5 tapping screw manufactured by Fuji Parts Co., Ltd. was also used as the main body of the fastening member.

Coat the resin male screw and the metal male screw with the curable resin composition (dissolved in an organic solvent) using a barrel coating machine so that the resin layer has a thickness of 1.3 μm. bottom. The curable resin composition is applied to each of the resin-made and metal-made male screws after degreasing pretreatment with an organic solvent (specifically, an organic solvent such as isopropyl alcohol). was applied to

After the above coating, they are left in an oven at 200° C. (that is, an ambient temperature of 190-200° C.) for 30 minutes to thermally cure the curable resin composition to produce fastening members having a resin layer on their external threads. Obtained. Example 1 (installed product) is a case in which a metal male screw is used as the main body of the fastening member. Example 2 (construction product) is a case in which a resin male screw is used as the main body of the fastening member.

The case where the curable resin composition was not applied to the male screw made of metal was taken as Comparative Example 1 (untreated product).

(Creation of mating member)
As a mating member, a sheet metal simulating an automobile body having a square hole and a female screw made of resin (manufactured by NIFCO; product name: screw grommet; Mohs hardness: less than 4) was used.

(Evaluation method)
After an environmental load test simulating an actual vehicle environment, the residual torque value was measured using a direct-reading torque wrench. The measurement results are shown in Table 1 below.

The rate of improvement (%) of the residual torque of the worked product in Table 1 above is calculated based on the residual torque value of the unworked product.

Claims (5)

A fastening member to be screwed into the resin mating member for fastening the member to be fastened to the resin mating member, comprising a main body having a thread on its outer periphery and a resin layer provided on the thread,
The resin layer comprises a cured product of a curable resin composition containing a curable resin and a filler,
The particles constituting the filler include particles having a hardness different from the hardness of the mating member,
A fastening member, wherein the average particle size of the filler is equal to or less than the thickness of the resin layer. 2. The fastening member according to claim 1, wherein the particles constituting the filler are particles having a hardness higher than that of the mating member. 3. The fastening member according to claim 1, wherein the filler has an average particle size of 0.1 to 20 μm. Claims 1 to 3, wherein the filler is zinc oxide, and the zinc oxide content is 10% by mass to 45% by mass with respect to 100% by mass of the curable resin composition. A fastening member according to any one of the preceding claims. A fastener comprising the fastening member according to any one of claims 1 to 4 and a resin mating member,
A fastener for fastening a member to be fastened, which is arranged between the fastening member and the mating member made of resin, to the mating member.

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