Hair-implanted spring

Abstract

To provide a flocked spring with less damage to a mating member.SOLUTION: A flocked spring 30 has a spring body 31, a coating layer 32 arranged on the surface of the spring body 31, an adhesive layer 33 arranged on the surface of the coating layer 32, and a flocked layer 34 made of a flocking filler fixed to the adhesive layer 33. The adhesive layer 33 is formed from an adhesive composition having an adhesive and a thixotropy application agent. In the flocked spring 30, a thickness of the adhesive layer 33 can be increased, and the number of flocking fillers constituting the flocked layer 34 can be increased.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a flocked spring having flocks on the surface of the spring. [Background technology]

[0002] For example, in a power tailgate of an automobile, a spring assembly for automatically opening and closing the tailgate is disposed between the tailgate and the vehicle body. The spring assembly has an expandable cylindrical shape and includes a compression coil spring between an outer cover member and an inner shaft member. When the compression coil spring is compressed, "buckling" may occur, causing the coil shaft to bend in a wavy or spiral shape. When the radially displaced portion of the coil shaft due to buckling comes into contact with the cover member disposed on the outside of the compression coil spring or the shaft member disposed on the inside, a tapping sound is generated. Therefore, compression coil springs used in spring assemblies are painted to provide rust resistance and are flocked to prevent tapping sounds. The flocking process involves applying an adhesive to the surface of the workpiece in advance and then attaching short fibers to the adhesive using electrostatic force or the like (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-224612 [Patent Document 2] Japanese Patent Application Publication No. 5-138813 [Patent Document 3] Japanese Patent Application Laid-Open No. 61-164682 Summary of the Invention [Problem to be solved by the invention]

[0004] In spring assemblies, the increased durability required of compression coil springs necessitates consideration of the impact on components related to the compression coil spring. For example, when the end of an inner shaft member is punched using a press, a slight protrusion may be formed on the outside. The surface of the shaft member is often coated with an electro-deposition coating, but when the compression coil spring slides against the shaft member, the coating on the protruding portion may peel off, exposing the base material. For this reason, compression coil springs are required to be designed to minimize damage to mating components. For example, in hair-planting processes, increasing the number of short fibers (filler) can reduce friction with the mating component and minimize damage. Increasing the number of filler particles requires an adhesive layer capable of fixing a large number of filler particles. For example, increasing the adhesive layer thickness would likely increase the number of filler particles. However, attempting to form a thick adhesive layer can result in dripping during application. Therefore, thicker adhesive layers are difficult to achieve.

[0005] The present disclosure has been made in consideration of the above-described circumstances, and an object of the present disclosure is to provide a hair-implanted spring that causes less damage to a mating member. [Means for solving the problem]

[0006] The flocked spring of the present disclosure comprises a spring body, a paint layer disposed on the surface of the spring body, an adhesive layer disposed on the surface of the paint layer, and a flocked layer made of a flocking filler fixed to the adhesive layer, wherein the adhesive layer is formed from an adhesive composition containing an adhesive and a thixotropic agent. [Effects of the Invention]

[0007] The adhesive layer constituting the flocked spring of the present disclosure is formed from an adhesive composition containing an adhesive and a thixotropic agent. The thixotropic agent is a material that imparts thixotropy to the adhesive composition. When the adhesive composition is imparted with thixotropy, the adhesive composition exhibits fluidity due to shear forces such as stirring during preparation and application. However, after application, the viscosity increases, the fluidity decreases, and dripping is suppressed. This allows the thickness of the formed adhesive layer to be increased, and the number of flocked fillers fixed to the adhesive layer, i.e., the number of flocked fillers constituting the flocked layer, can be increased. Furthermore, the inventors' studies have confirmed that the number of flocked fillers fixed in a nearly upright position relative to the surface of the adhesive layer can be increased. Thus, with the flocked spring of the present disclosure, the desired flocking state can be achieved by increasing the thickness of the adhesive layer, thereby reducing friction with the mating component and minimizing damage to the mating component.

[0008] Incidentally, Patent Document 3 describes a method for decoratively finishing the interior of an automobile body, in which electrodeposition coating is applied to the interior of the vehicle body, the coating is baked to form an electrodeposition coating film, and then a synthetic resin adhesive is applied and used as a counter electrode to electrostatically flock short fibers. It also describes that the adhesive used for electrostatic flocking may contain an anti-sagging agent in addition to an adhesive synthetic resin component. However, the electrostatic flocking described in Patent Document 3 is intended for decoratively decorating the interior of the vehicle body, and it is not intended that the flocked layer will come into contact with a mating component. Therefore, Patent Document 3 does not consider the thickness of the adhesive layer or the state of flocking filler, nor does it describe or suggest increasing the thickness of the adhesive layer. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a partial schematic view of a spring assembly including a compression coil spring, which is one embodiment of a hair-implanted spring of the present disclosure. FIG. [Figure 2] FIG. 2 is a cross-sectional view of the compression coil spring taken along a radial direction of the wire. [Figure 3]1A and 1B are schematic diagrams illustrating the planting state of a filler for flocking, for explaining an upright filler in the present disclosure, where (a) shows the vertical state and (b) shows the inclined state. [Figure 4] 1 is a graph showing the thickness of adhesive layers formed using adhesive compositions with and without a thixotropic agent. [Figure 5] 1 is a graph showing the measurement results of the amount of wear in a wear test. [Figure 6] 1 is a graph plotting the number of fillers against the thickness of the adhesive layer. [Figure 7] 1 is a graph plotting the number of upright fillers against the thickness of the adhesive layer. [Figure 8] 1 is a graph plotting filler gradient percentage against adhesive layer thickness. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Hair-implanted springs> As one embodiment of the hair-implanted spring of the present disclosure, a form used as a compression coil spring that constitutes a spring assembly will be described. First, the configuration of the spring assembly and compression coil spring of this embodiment will be described. FIG. 1 shows a partial schematic diagram of the spring assembly. FIG. 2 shows a cross-sectional view of the wire diameter of the compression coil spring housed in the spring assembly. As shown in FIG. 1, the spring assembly 1 has a cover member 10, a guide member 20, and a compression coil spring 30. The spring assembly 1 is used in a flip-up power tailgate of a vehicle.

[0011] The cover member 10 is made of polyamide resin and has a cylindrical shape with a bottom that opens upward. A spring seat 100 is disposed on the upper surface of the bottom wall of the cover member 10. The lower end of the cover member 10 is attached to the vehicle's back door (not shown) so as to be able to swing. The guide member 20 has a cylindrical shape and protrudes upward from the upper surface of the bottom wall of the cover member 10. The guide member 20 is disposed inside the spring seat 100. The guide member 20 is made of iron and has a surface that is coated with cathodic electrodeposition. The compression coil spring 30 is housed within the cover member 10. The compression coil spring 30 is disposed around the guide member 20 as its axis, and its lower end winding portion is annularly attached to the spring seat 100. The compression coil spring 30 repeatedly expands and contracts in the vertical direction in response to the opening and closing of the back door.

[0012] As shown in FIG. 2, the compression coil spring 30 includes, in the radial direction, a spring body 31, a coating layer 32, an adhesive layer 33, and a flocking layer 34. The spring body 31 is made of spring steel and has a zinc phosphate coating formed on its surface. The coating layer 32 is disposed on the surface of the spring body 31. The coating layer 32 contains a modified epoxy ester resin and a melamine resin as resins that form the coating. The coating layer 32 has a thickness of 25 μm. The adhesive layer 33 is disposed on the surface of the coating layer 32. The adhesive layer 33 is formed from an adhesive composition containing an adhesive containing a modified epoxy resin and an anti-rust pigment, and a thixotropic agent containing amorphous silica. The adhesive layer 33 has a thickness of approximately 41 μm. Because a flocking filler is fixed to the adhesive layer 33, the thickness of the adhesive layer 33 is affected by the flocking filler and varies. The pencil hardness of the surface 330 of the adhesive layer 33 is 3H.

[0013] The flock layer 34 is disposed on the surface 330 of the adhesive layer 33. The flock layer 34 is made of flock filler made of nylon 66 fiber. The flock filler has a length of 800 μm, with a portion embedded in the adhesive layer 33 and the other portion protruding outward from the adhesive layer 33. The flock layer 34 is formed by the other portion of the flock filler protruding from the adhesive layer 33. On the surface 330 of the adhesive layer 33, an arbitrary 1.2 mm 2The number of flock fillers fixed in this range is 76, of which 60 are upright fillers fixed in a substantially upright state (a state inclined at an angle of up to 45° from a perpendicular state to the surface 330 of the adhesive layer 33), and 16 are inclined fillers. In this case, the inclination rate of the flock fillers in the flock layer 34 (the proportion of inclined fillers) is 21%. The compression coil spring 30 is included in the concept of an implanted spring of the present disclosure.

[0014] Next, the effects of the compression coil spring of this embodiment will be described. According to this embodiment, the adhesive layer 33 is formed from an adhesive composition containing an adhesive and a thixotropic agent. The thixotropic agent increases the viscosity of the adhesive composition when it is applied, reducing its fluidity and preventing dripping. This allows the thickness of the formed adhesive layer 33 to be increased, allowing more filler fibers to be fixed to the adhesive layer 33. Furthermore, the number of upright filler fibers in the flocked layer 34 is large. Therefore, the compression coil spring 30 can reduce friction with the guide member 20, making it less likely to cause damage to the guide member 20, such as paint peeling.

[0015] The above describes one embodiment of the hair-implanted spring of the present disclosure, but the hair-implanted spring of the present disclosure is not limited to this form, and can be embodied in various forms with modifications and improvements that can be made by a person skilled in the art, as long as they do not deviate from the gist of the present disclosure.

[0016] [Spring body] The type of spring body is not particularly limited, and may be a coil spring, leaf spring, spiral spring, torsion bar, or the like. The spring body is preferably made of spring steel, which is commonly used for springs, such as carbon steel, alloy steel, and stainless steel. For example, after hot or cold forming the spring steel, the surface roughness of the spring body may be adjusted by shot peening or the like. It is also desirable to form a phosphate coating, such as zinc phosphate or iron phosphate, on the base surface of the spring body. Forming a paint layer on the phosphate coating improves corrosion resistance and the adhesion of the paint layer. In particular, when the phosphate is zinc phosphate, corrosion resistance is further improved. The phosphate coating may be formed by a known method. Examples of such methods include an immersion method in which the spring body is immersed in a phosphate solution bath, and a spray method in which the phosphate solution is sprayed onto the spring body using a spray gun or the like.

[0017] [Paint layer] The coating layer is disposed on the surface of the spring body. There are no limitations on the type of coating material that forms the coating layer. Examples include solvent-based coatings, water-based coatings, and powder coatings. Solvent-based and water-based (liquid) coatings have the advantage of easily forming a thin coating film (coating layer). Furthermore, they are easy to form a smooth coating film, and film thickness control is easy. For example, solvent-based coatings allow for the downsizing of equipment. Electrodeposition coating, in which the spring body is immersed in water-based coating and a voltage is applied using the spring body as the anode or cathode, can form a coating film that is chemically stable and has high mechanical strength. Powder coatings, which do not use organic solvents, have a small impact on the environment. Furthermore, compared to liquid coatings, there is less paint scattering, making them easier to recover, and they can easily be used to form thicker coatings.

[0018] Both types of paints consist of a base material for film formation: resin, pigment, additives, and solvent. Resins can be selected from thermosetting and thermoplastic resins. Thermosetting resins include epoxy resin, polyester resin, acrylic resin, phenolic resin, melamine resin, urethane resin, and silicone resin. Thermoplastic resins include fluororesin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, acrylonitrile-butadiene-styrene (ABS) resin, methacrylic resin, and nylon resin. Epoxy resins are preferred for enhanced rust resistance. Modified epoxy resins are particularly suitable. Melamine resins are also preferred for enhanced abrasion resistance, heat resistance, and weather resistance. For example, epoxy-melamine paints containing both modified epoxy resin and melamine resin are suitable.

[0019] Pigments include color pigments, extender pigments, and anti-rust pigments. Color pigments include inorganic pigments such as carbon black, titanium dioxide, red iron oxide, and yellow ochre, and organic pigments such as quinacridone red, phthalocyanine blue, and benzidine yellow. Extender pigments include aluminum silicate, calcium carbonate, magnesium carbonate, talc, silica, and barium sulfate. Anti-rust pigments include iron phosphate, aluminum phosphate, and calcium phosphate. Additives include surface conditioners, ultraviolet absorbers, antioxidants, antistatic agents, and flame retardants.

[0020] The thickness of the coating layer can be determined appropriately taking into consideration the mechanical strength, anti-corrosion performance, and the required dimensions of the flocked spring. To fully achieve the desired performance, a thickness of 10 μm or more, and even 15 μm or more, is preferable. On the other hand, from the viewpoint of design robustness, a thickness of 35 μm or less, and even 25 μm or less, is preferable.

[0021] [Adhesive layer] The adhesive layer is disposed on the surface of the coating layer. The adhesive layer is formed from an adhesive composition containing an adhesive and a thixotropic agent. The adhesive may be solvent-based or emulsion-based. Examples include adhesives primarily composed of epoxy resin, urethane resin, acrylic resin, vinyl acetate resin, polyimide resin, silicone resin, etc. The adhesive may be selected appropriately taking into account its adhesion to the resin of the coating layer. Among these, solvent-based adhesives primarily composed of modified epoxy resin are preferred because they have high rust prevention properties and can be used as a one-component lacquer. The adhesive may contain pigments, solvents, and additives in addition to the resin component. Pigments include color pigments, extender pigments, and rust-preventive pigments, similar to the paints of the coating layer described above. Additives include surface conditioners, ultraviolet absorbers, antioxidants, antistatic agents, and flame retardants.

[0022] The thixotropic agent may be any agent capable of imparting thixotropy to the adhesive composition. The thixotropic agent may be composed of a pigment such as amorphous silica, a resin such as an amino resin, a solvent, an additive, or the like. From the viewpoint of suppressing dripping of the adhesive composition and increasing the thickness of the adhesive layer, the amount of the thixotropic agent blended is desirably 5 parts by mass or more per 100 parts by mass of the adhesive, with 10 parts by mass or more being preferable. Conversely, from the viewpoint of suppressing a decrease in adhesion, etc., due to a relative decrease in the proportion of the resin component of the adhesive in the adhesive composition, the amount of the thixotropic agent blended is desirably 15 parts by mass or less per 100 parts by mass of the adhesive.

[0023] In addition to the adhesive and the thixotropic agent, the adhesive composition may contain a roughening solvent, a retarder (drying retarder), and the like. The roughening solvent is a solvent that acts to increase the surface roughness of the object (painted surface) to which the adhesive composition is applied. When the surface roughness of the painted surface is high, the anchor effect increases the adhesion between the paint layer and the adhesive layer, suppressing peeling of the adhesive layer. As a result, the flock filler is less likely to fall off, and the friction reduction effect with the mating member is sustained. For example, when the paint layer is formed by cationic electrodeposition coating, the surface is smooth, so the adhesion with the adhesive layer is likely to decrease. In such cases, it is effective to increase the surface roughness using a roughening solvent. Furthermore, adding a retarder can prevent the adhesive composition from drying out between application and flocking.

[0024] The flock filler is fixed to the adhesive layer. The thickness of the adhesive layer is not constant due to the influence of the flock filler; for example, after flocking, there are portions where the thickness is about 1.5 times that of the adhesive layer before flocking. From the viewpoint of fixing a large number of flock fillers by increasing the thickness of the adhesive layer, the thickness of the adhesive layer is preferably 20 μm or more, 22 μm or more, or even 25 μm or more before flocking, and 25 μm or more, 26 μm or more, or even 29 μm or more after flocking. On the other hand, from the viewpoint of suppressing dripping, the thickness of the adhesive layer is preferably 65 μm or less before flocking and 90 μm or less, 88 μm or less, or even 75 μm or less after flocking.

[0025] According to the inventors' investigations, the surface of an adhesive layer containing a thixotropic agent is harder than that containing no thixotropic agent. When the surface of the adhesive layer is harder, it becomes less susceptible to wear during use and the retention of the flock filler is improved. The surface hardness of the adhesive layer is preferably 3H or more in pencil hardness measured in accordance with JIS K5600-5-4:1999 "Scratch Hardness (Pencil Method)."

[0026] [Hair transplant layer] The flocking layer is made of flock fillers fixed to the adhesive layer. Some of the flock fillers are embedded in the adhesive layer, while other parts protrude outward from the adhesive layer. The flocking layer is formed by the other parts of the flock fillers protruding from the adhesive layer.

[0027] The type of filler for flocking (hereinafter sometimes simply referred to as "filler") is not particularly limited, and may be an organic filler or an inorganic filler. Organic fillers are more flexible than inorganic fillers. Therefore, they are less likely to break when attached and are easier to maintain in a flocked state. Examples of organic fillers include nylon fibers, polyester fibers, rayon fibers, cotton fibers, polyethylene fibers, aramid fibers, and fluorine fibers. Of these, it is preferable to use one or more fibers selected from nylon fibers, polyester fibers, rayon fibers, cotton fibers, and polyethylene fibers. Examples of inorganic fillers include glass fibers.

[0028] The surface resistance of the filler for flocking is 1 x 10 5 Ω or more 1×10 18 In this specification, the surface resistance is measured using a super insulation meter "SM-8220" manufactured by Hioki E.E. Corporation. The surface resistance of the filler for flocking is preferably 1×10 5 If the surface resistance is less than Ω, the electrical conductivity is high and discharge occurs easily, which reduces the ability of the filler to fly. This makes it difficult to implant the filler using electrostatic force. A more suitable surface resistance is 1×10 6 Ω or more. On the other hand, the surface resistance is 1×10 18 If the surface resistance is more than 100 Ω, the filler will be too charged and the flying ability will be poor. This makes it difficult to plant the filler using electrostatic force. A more suitable surface resistance is 1×10 13 Ω or less, even 1×10 10 In addition, when the filler for flocking is circulated during the flocking process and dried, the surface resistance value increases.

[0029] As the flock filler, fibers that have been subjected to various surface treatments, such as electrodeposition treatment, water absorption treatment, water repellency treatment, and primer treatment, can be used to improve dispersibility and suppress excessive charging. For example, it is desirable for the flock filler to have an electrodeposition treatment film on its surface. By having an electrodeposition treatment film, the surface resistance of the filler can be adjusted to a desired value. This suppresses excessive charging of the filler and improves its flying power when flocked. Furthermore, because fibers tend to aggregate, they tend to become tangled and form clumps if left as is. In this regard, having an electrodeposition treatment film on the surface improves the dispersibility of the fibers (flock filler). This suppresses filler aggregation and enables the realization of a nearly uniform flocked state.

[0030] The electrodeposition coating is formed by electrodeposition of the surface of fibers used as flock fillers. One method of electrodeposition is to treat the fibers with tannin, tartar emetic, or the like to produce tannin compounds on the fiber surface. Another method is to treat the fibers with a solution containing an appropriate mixture of inorganic salts such as barium chloride, magnesium sulfate, sodium silicate, and sodium sulfate, quaternary ammonium salts, higher alcohol sulfate ester salts, betaine-type surfactants, and organic silicon compounds (colloidal silica), thereby adhering the silicon compounds to the fiber surface.

[0031] The filler for flocking is fibrous. There are no particular limitations on the longitudinal length of the filler, but if the filler is too short, it will be buried in the adhesive layer, making it impossible to achieve the desired flocking state. For example, the length of the filler is desirably 50 μm or more. 200 μm or more, and even more preferably 500 μm or more. On the other hand, if the filler is too long, it will collapse, making it impossible to achieve the desired flocking state. For example, the length of the filler is desirably 2000 μm or less. 1000 μm or less, and even more preferably 600 μm or less. There are no particular limitations on the maximum length (thickness) of the filler in the transverse direction, but if the filler is too thin, it will curl under its own weight, making it impossible to achieve the desired flocking state. For example, the thickness of the filler is desirably 5 μm or more. 10 μm or more, and even more preferably 20 μm or more. On the other hand, if the filler is too thick, the feel will be poor. For example, the thickness of the filler is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less.

[0032] The placement of the filler for flocking does not necessarily have to be uniform throughout the entire flocked spring. For example, the number of filler pieces may be increased in areas that may come into contact with the mating member, and decreased in areas that may not come into contact. From the perspective of reducing friction with the mating member, it is desirable to have a large number of filler pieces for flocking. For example, on the surface of the adhesive layer, 2 When the above range is taken as the measurement area, the number of fillers for hair implantation fixed in the measurement area is preferably 32 or more, more preferably 35 or more, and even more preferably 40 or more.

[0033] The flock fillers can be planted not only upright but also at an angle relative to the surface of the spring body. It is believed that when the planted fillers cross each other, the amount of energy absorbed by the flock layer increases, improving sound deadening. On the other hand, increasing the number of upright fillers increases the effect of reducing friction with the mating component, which is effective in minimizing damage to the mating component. Therefore, from the perspective of reducing friction with the mating component, it is desirable that the number of upright fillers fixed in the measurement area in a substantially upright position relative to the surface of the adhesive layer be 11 or more. It is even more desirable to have 12 or more, and even more desirable to have 16 or more.

[0034] In this disclosure, "upright fillers fixed in a substantially upright state" refers to fillers fixed at an inclination angle of up to 45° from a perpendicular state to the surface of the adhesive layer. The method for identifying upright fillers is explained below. Figure 3 shows a schematic diagram of the planted state of flock fillers. In Figure 3, (a) shows the vertical state, and (b) shows the inclined state. When a flock filler with a circular cross section is cut along the surface of the adhesive layer as shown by the dotted line in Figure 3, if it is inclined, the cross section will be elliptical. As shown in Figure 3(b), if the angle of the inclined filler from the adhesive layer is θ, the relationship between the length d' of the major axis of the cross section of the inclined filler and the diameter d of the non-inclined filler can be expressed by the following formula (I): d'=d / sinθ (I) In this disclosure, the filler is cut by running a medical scalpel along the surface of the implanted spring, and the cross section is observed under a scanning electron microscope (SEM). A filler whose major axis length of the cross section is 1.41 times or less the diameter (thickness) of the filler used for implantation (corresponding to 45°≦θ≦90° in the above formula (I)) is considered to be an upright filler.

[0035] When the fillers other than the upright fillers among the flock fillers fixed in the measurement area on the surface of the adhesive layer are defined as inclined fillers, the proportion of inclined fillers in the entire filler can be expressed as the inclination ratio of the flock fillers. That is, the inclination ratio of the flock fillers in the measurement area can be calculated by the following formula (II). Gradient rate (%) = Number of gradient fillers in the measurement area / Number of fillers in the measurement area (II) From the viewpoint of reducing friction with the mating member, the gradient of the filler for flocking is preferably 66% or less, more preferably 65% ​​or less, and even more preferably 50% or less.

[0036] <Manufacturing method for hair-implanted springs> The flocked spring of the present disclosure can be manufactured, for example, as follows. First, the spring body is subjected to, as necessary, adjustment of surface roughness by shot peening or the like, and formation of a phosphate coating. Next, a paint for forming a coating layer is applied to the spring body. A known method, such as brushing, spraying, or dipping, may be used to apply the paint, depending on the type of paint. Next, an adhesive composition is applied to the surface of the coating film. The adhesive composition may be applied by brushing, spraying, or the like. For example, when using a spray method, the spray gun's discharge pressure, discharge amount, movement speed, spray time, workpiece distance, and the like may be appropriately adjusted to achieve the desired adhesive layer thickness. Next, a flocking filler is applied to the surface coated with the adhesive composition. For flocking, an electrostatic spray gun, an electrostatic fluidized bed, or the like may be used. Finally, the flocked spring body is heated. Heating may be performed using a commonly used electric furnace, hot air dryer, or the like. By heating, the coating film and the applied composition dry and solidify, forming a coating layer and an adhesive layer. The heating temperature, heating time, etc. may be determined appropriately depending on the type of coating material and adhesive. For example, the heating temperature is preferably 130 to 170°C, and the heating time is preferably 10 to 40 minutes. [Example]

[0037] Next, the present disclosure will be described more specifically with reference to examples. (1) Difference in adhesive layer thickness with and without thixotropic additives The thickness of the adhesive layer formed was investigated using adhesive compositions with and without a thixotropic agent. The substrate on which the adhesive layer was formed was a rectangular steel plate (70 mm long x 150 mm wide, 0.8 mm thick) with a zinc phosphate coating formed on its surface and then coated with epolamine. The epolamine coating was an epoxy-melamine-based paint containing modified epoxy ester resin and melamine resin, and the paint was sprayed with a spray gun to a target thickness of 25 μm. Table 1 shows the components of the epoxy-melamine-based paint. [Table 1]

[0038] Two types of adhesive compositions were prepared, one with a thixotropy-imparting agent and the other with no thixotropy-imparting agent. Table 2 shows the components of the adhesive compositions used. Table 3 shows the components of the adhesive and thixotropy-imparting agent in the adhesive compositions. [Table 2] [Table 3]

[0039] Each adhesive composition was sprayed onto the epolamine-coated surface of the substrate using a spray gun at two different liquid temperatures: 10°C and 35°C. The sample was then placed in a hot air dryer and heated at 150°C for 20 minutes to form a coating layer and an adhesive layer. Six samples were produced using the same adhesive composition and liquid temperature (Samples No. 1 to 6). Figure 4 shows the thickness of the adhesive layer formed. As shown in Figure 4, when an adhesive composition containing a thixotropic agent was used, the adhesive layer thickness was more than twice as thick as when an adhesive composition not containing a thixotropic agent was used, regardless of the liquid temperature. Furthermore, a tendency for the adhesive composition to have a slightly thicker thickness was observed when the liquid temperature of the adhesive composition was higher.

[0040] (2) Difference in wear amount depending on whether or not a thixotropic agent is present Adhesive layers were formed with and without a thixotropic agent, and the abrasion resistance of the test pieces after flocking was examined.

[0041] <Production of test specimens> First, a zinc phosphate film was formed on the surface of a steel plate, similar to the substrate in (1) above, and then an epolamine coating was applied. Next, two types of adhesive compositions, one with a thixotropy-imparting agent and the other without, were sprayed onto the epolamine-coated surface with a spray gun at a liquid temperature of 35°C. The components of the epolamine coating paint and adhesive composition are as shown in Tables 1 to 3 above. Next, a flock filler was sprayed onto the adhesive composition-coated surface using an electrostatic coating gun. The flock filler was an organic filler made of nylon 66 fiber (20 μm in diameter, 800 μm in length, with an electrodeposition treatment film, and a surface resistance of 10 6 ~10 7 Ω) was used. The steel sheet was then placed in a hot air dryer and heated at 150°C for 10 minutes to form a paint layer and an adhesive layer. In this way, test specimens were produced in which a zinc phosphate coating, paint layer, adhesive layer, and flock layer were formed on the surface of the steel sheet in this order from bottom to top. The paint layer on the test specimens was 25 μm thick. Two types of adhesive layers were formed with different thicknesses. When an adhesive composition without a thixotropy-imparting agent was used, the thicknesses were 27 μm and 28 μm, and when an adhesive composition with a thixotropy-imparting agent was used, the thicknesses were 53 μm and 60 μm. Three test specimens were produced for each adhesive layer thickness.

[0042] Separately, a steel plate in a state before flocking, i.e., with the adhesive composition sprayed onto the Epolamine-coated surface, was placed in a hot air dryer and heated at 150°C for 10 minutes to form a coating layer and an adhesive layer. The surface hardness of the formed adhesive layer was then measured in accordance with JIS K5600-5-4:1999 "Scratch hardness (pencil method)." The pencil hardness of the adhesive layer without the thixotropy-imparting agent was H, and the pencil hardness of the adhesive layer with the thixotropy-imparting agent was 3H.

[0043] <Test Method> A Taber abrasion test was conducted in accordance with JIS K7204:1999 "Plastics - Abrasion test method using abrasive wheels" to measure the amount of wear on the test specimens. The test specimens were 100 mm in diameter, disc-shaped, the abrasive wheel was CS10, and the abrasive wheel rotation speed was 72 rpm.

[0044] <Test Results> The results of measuring the amount of wear on the test pieces are shown in Figure 5. As shown in Figure 5, the amount of wear was less when an adhesive composition containing a thixotropy-imparting agent was used. The reason for this is thought to be that the adhesive layer was thick, resulting in a large number of fillers and high retention, and that the number of upright fillers was high (the inclination rate of the fillers was small), which reduced friction with the mating component (the abrasion wheel in this wear test).

[0045] (3) Evaluation of the hair transplant condition Adhesive layers of various thicknesses, with and without a thixotropic agent, were formed on the coil springs, and the filler implantation state was examined when implantation was performed.

[0046] <Manufacturing of hair-implanted springs> Similar to the procedure described in (2) above, implanted springs were manufactured by forming a zinc phosphate coating, a paint layer, an adhesive layer, and a flocked layer on the surface of a coil spring. Specifically, a zinc phosphate coating was first formed on a spring steel coil spring, followed by an epolamine coating. Next, two types of adhesive compositions, one containing a thixotropic agent and the other not, were sprayed onto the epolamine-coated surface at a liquid temperature of 35°C using a spray gun. The components of the epolamine coating paint and adhesive composition are listed in Tables 1 to 3 above. Next, an organic filler made of nylon 66 fiber (same as above) was sprayed onto the adhesive composition-coated surface using an electrostatic spray gun. The spring was then placed in a hot air dryer and heated at 150°C for 10 minutes to form a paint layer and an adhesive layer. The dimensions of the coil spring used were a wire diameter of 3.6 mm, an outer diameter of 27.5 mm, a free length of 724 mm, and a total number of turns of 57. The thickness of the paint layer on the implanted spring was 25 μm.

[0047] <Evaluation method> The implantation state of the filler was evaluated by counting the number of fillers in a predetermined measurement area as follows. First, the surface of the implanted spring was cut with a medical scalpel, and the cut surface was observed with an SEM. Then, 2 The number of fillers in the measurement area was counted. Next, the number of upright fillers whose major axis length in the cross section of the filler was 1.41 times or less the thickness of the filler used was counted. Then, the slope rate of the filler was calculated using the above formula (II).

[0048] <Evaluation results> As an example, the evaluation results of the planting condition inside the coil of a hair-implanted spring are shown below. Figure 6 shows a graph plotting the number of fillers against the thickness of the adhesive layer. Figure 7 shows a graph plotting the number of upright fillers against the thickness of the adhesive layer. Figure 8 shows a graph plotting the filler gradient against the thickness of the adhesive layer. As shown in Figure 6, when hair was planted in an adhesive layer containing a thixotropic agent, the number of fixed fillers increased. In this case, the number of fillers increased even when the adhesive layer was relatively thin, at 20 to 40 μm. Furthermore, as shown in Figures 7 and 8, the adhesive layer containing a thixotropic agent had a greater number of upright fillers and a lower filler gradient.

[0049] (4) Durability evaluation Seven implanted springs with different adhesive layer thicknesses manufactured in (3) above were each mounted in a spring assembly (see Figure 1 above) and subjected to a durability test in which the implanted springs were stretched and contracted vertically 30,000 times. Durability was then evaluated by inspecting the condition of the guide member (inner tube). The guide member was made of iron and had a cylindrical shape, with its surface coated with cationic electrodeposition. The adhesive layers of the implanted springs were all formed from an adhesive composition containing a thixotropic agent. Durability was evaluated based on the degree of peeling of the paint on the guide member. A case in which no peeling was observed was rated as excellent durability (indicated by a circle in Table 4 below), and a case in which partial peeling was observed was rated as slightly poor durability (indicated by a triangle in the same table). The durability evaluation results are shown in Table 4. [Table 4]

[0050] As shown in Table 4, when the thickness of the adhesive layer on the inside of the coil of the hair-implanted spring was 29 μm or more, the paint on the guide member did not peel off and showed high durability. However, when the thickness of the adhesive layer was 26 μm, some of the paint on the guide member peeled off. [Explanation of symbols]

[0051] 1: spring assembly, 10: cover member, 100: spring seat, 20: guide member, 30: compression coil spring (flocked spring), 31: spring body, 32: paint layer, 33: adhesive layer, 330: surface of adhesive layer, 34: flocked layer.

Claims

1. A spring body; a coating layer disposed on the surface of the spring body; an adhesive layer disposed on the surface of the coating layer; a flocking layer made of a flocking filler fixed to the adhesive layer; and the adhesive layer is formed from an adhesive composition having an adhesive and a thixotropic agent; 1.2 mm on the surface of the adhesive layer ２ When the measurement area is the range of the hair implantation spring, the number of upright fillers fixed in the measurement area in a substantially upright state relative to the surface of the adhesive layer is 11 or more.

2. A spring body; a coating layer disposed on the surface of the spring body; an adhesive layer disposed on the surface of the coating layer; a flocking layer made of a flocking filler fixed to the adhesive layer; and the adhesive layer is formed from an adhesive composition having an adhesive and a thixotropic agent; 1.2 mm on the surface of the adhesive layer ２ When the range of the above is set as a measurement area, the slope rate of the filler for hair implantation in the measurement area is 66% or less.

3. A spring body; a coating layer disposed on the surface of the spring body; an adhesive layer disposed on the surface of the coating layer; a flocking layer made of a flocking filler fixed to the adhesive layer; and The adhesive layer is formed from an adhesive composition containing an adhesive and a thixotropic agent, and the thickness of the adhesive layer is 25 μm or more and 90 μm or less.

4. A spring body; a coating layer disposed on the surface of the spring body; an adhesive layer disposed on the surface of the coating layer; a flocking layer made of a flocking filler fixed to the adhesive layer; and The adhesive layer is formed from an adhesive composition containing an adhesive and a thixotropic agent, and the surface of the adhesive layer has a pencil hardness of 3H or more.

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