Resin film, laminate, and method for manufacturing the laminate

Abstract

To provide a resin film with a low coefficient of dynamic friction and excellent water repellency. [Solution] A resin film formed from a powder coating containing ethylene-based polymer particles that satisfy the following requirements (I) and (II), and that satisfies the following requirement (i). (I) The intrinsic viscosity [η] measured in decalin at 135°C is 5-50 dL / g. (II) The average particle size d50 is 1 to 500 μm. (i) The unfolded surface area ratio (Sdr) of the resin film surface is 30% or more.

Description

Technical Field

[0001] The present invention relates to a resin film, a laminate, and a method for producing the laminate.

Background Art

[0002] A wiping molded body such as a wiper blade is a molded body that has a wiping function of dynamically removing moisture or the like from an object such as glass without substantially absorbing moisture or the like, and is widely used. These molded bodies are required to conform to and follow the shape of the object, such as glass, and remain soft even when the temperature changes. Such a molded body, for example, a wiper blade, as a member that contacts an object such as glass, a member made of a rubber material, specifically, a natural rubber or a synthetic rubber (e.g., polyolefin rubber, chloroprene rubber, silicone rubber, polyurethane rubber) or the like is used.

[0003] Since the rubber material exhibits a relatively high dynamic friction coefficient, when dynamically wiping foreign substances such as moisture on the surface of an object such as glass, the resistance is large and the operating load tends to increase. Therefore, when trying to improve the wiping performance of a member made of such a rubber material, the friction coefficient increases, the operating load increases, and noise may be generated due to friction, or damage may occur to the object such as glass.

[0004] For the purpose of solving this problem, specifically, for the purpose of reducing the dynamic friction coefficient of the member, it has been reported that a paint containing polyolefin powder is applied to the rubber material. For example, Patent Document 1 discloses that a paint containing a specific ultra-high molecular weight polyethylene powder can obtain a coating film with a small dynamic friction coefficient.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The inventors investigated and found that although the coating described in Patent Document 1 has a low coefficient of dynamic friction, there is room for improvement in terms of water repellency.

[0007] This invention has been made in view of the above-mentioned problems, and aims to provide a resin film that has a low coefficient of dynamic friction and excellent water repellency. [Means for solving the problem]

[0008] As a result of the inventor's diligent efforts to find a way to solve the aforementioned problems, the inventor discovered that the problems can be solved by the following configuration example, and thus completed the present invention. The following are examples of the configuration of the present invention. In this specification, "A~B" indicating a numerical range means A or greater and B or less.

[0009] [1] A resin film formed from a powder coating containing ethylene polymer particles that satisfy the following requirements (I) and (II), and that satisfies the following requirement (i). (I) The intrinsic viscosity [η] measured in decalin at 135°C is 5-50 dL / g. (II) The average particle size d50 is 1 to 500 μm. (i) The unfolded surface area ratio (Sdr) of the resin film surface is 30% or more.

[0010] [2] The resin film according to [1], wherein the expanded surface area ratio (Sdr) is 80% or more.

[0011] [3] The resin film according to [1] or [2], wherein the particle size d50 of the ethylene polymer particles is 1 to 200 μm.

[0012] [4] The resin film according to any one of [1] to [3], wherein the intrinsic viscosity [η] of the ethylene polymer particles is 5 to 15 dL / g.

[0013] [5] A laminate having a base material and a resin film according to any one of [1] to [4]. [6] The laminate according to [5], wherein the base material is metal.

[0014] [7] A step of coating a substrate with a powder coating containing ethylene polymer particles that satisfy the following requirements (I) and (II), A step of forming a resin film on a substrate by baking the powder coating applied to the substrate under conditions that satisfy the following formula (1) and in an air atmosphere, including, A method for manufacturing laminates. (I) The intrinsic viscosity [η] measured in decalin at 135°C is 5-50 dL / g. (II) The average particle size d50 is 1 to 500 μm. Baking temperature (°C) + 0.65 × baking time (minutes) < 200 ···(1)

[0015] [8] The manufacturing method according to [7], wherein the substrate is a metal. [Effects of the Invention]

[0016] According to the present invention, it is possible to form a resin film that has a low coefficient of dynamic friction and excellent water repellency (large water contact angle). Therefore, the resin film according to the present invention and the laminate having the resin film have excellent wiping properties for liquids and the like on the surface of an object, and can suppress friction with the object and damage to the object. Furthermore, the resin film according to the present invention is particularly suitable for use on substrates (especially metal substrates) where liquid-repellent properties are required. Specifically, the resin film according to the present invention can be suitably used as a substitute material for fluorine coatings on substrates where fluorine coatings are required, and the resin film according to the present invention can be used as a substitute material for fluororesin films that are harmful to the environment and human health. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a scanning electron microscope (SEM) image of the surface of the resin film obtained in Example 1. [Figure 2] Figure 2 is a scanning electron microscope (SEM) image of the surface of the resin film obtained in Example 4. [Figure 3] Figure 3 is a scanning electron microscope (SEM) image of the surface of the resin film obtained in Example 7. [Figure 4] Figure 4 is a scanning electron microscope (SEM) image of the surface of the resin film obtained in Comparative Example 1. [Figure 5] Figure 5 is a scanning electron microscope (SEM) image of the surface of the resin film obtained in Comparative Example 2.

Mode for Carrying Out the Invention

[0018] ≪Resin Film≫ The resin film according to the present invention (hereinafter also referred to as "the present resin film") is formed from a powder coating (hereinafter also referred to as "the present coating") containing ethylene-based polymer particles (hereinafter also referred to as "particles (A)") that satisfy the following requirements (I) and (II), and satisfies the following requirement (i). Requirement (i): The developed interfacial area ratio (Sdr) of the surface of the present resin film is 30% or more.

[0019] The developed interfacial area ratio (Sdr) is an index of the roughness of the surface of the present resin film and is one of the surface roughness parameters (ISO 25178). The developed interfacial area ratio (Sdr) obtains the surface area when irregularities are taken into account with respect to the normal non-rough surface area, and is an index (Sdr of a smooth surface is 0%) indicating the rate of increase in the surface area, that is, how much the developed area (surface area) of the defined region has increased with respect to the area of the defined region, that is, it represents the rate of increase in the surface area. The more dense the shape of the surface of the resin film formed from the present coating and the more intense the undulations, the larger the value of the developed interfacial area ratio (Sdr).

[0020] The expanded surface area ratio (Sdr) is 30% or more, preferably 80% or more, more preferably 150% or more, and even more preferably 200% or more. There is no particular upper limit to the expanded surface area ratio (Sdr), but it is usually 1000%. Resin films with an expanded surface area ratio (Sdr) within the aforementioned range tend to have large surface irregularities, a large water wetting contact angle, and excellent water repellency. By using this paint containing particles (A), and further by adjusting the resin film formation conditions, in particular by forming the resin film under baking conditions in an air atmosphere and satisfying the following formula (1), a resin film with an expanded interface area ratio (Sdr) within the aforementioned range can be easily formed. The expanded surface area ratio (Sdr) is specifically measured in accordance with ISO 25178-2:2012.

[0021] The resin film has a water-wetting contact angle of preferably 100° or more, more preferably 110° or more. There is no particular upper limit, but for example, it could be 170°. A resin film having a water-wetting contact angle greater than or equal to the aforementioned lower limit can be said to have a large water-wetting contact angle and excellent water repellency, and can be suitably used in applications where water repellency is required. The water wetting contact angle can be measured specifically by the method described in the following examples.

[0022] The resin film has a surface coefficient of dynamic friction of preferably 0.3 or less, more preferably 0.2 or less. The lower limit is not particularly limited, but for example, it is 0.05. A resin film with a dynamic friction coefficient below the aforementioned upper limit can be said to have a low dynamic friction coefficient, resulting in a reduced operating load. This makes it easy to suppress noise caused by friction between the resin film and the object it contacts, and to prevent damage to the object the resin film contacts. The coefficient of dynamic friction can be measured specifically by the method described in the following examples.

[0023] The thickness of this resin film is preferably 20 to 200 μm, and more preferably 20 to 150 μm.

[0024] <Powder paint> The paint is not particularly limited as long as it contains particles (A), and may contain conventionally known additives used in powder coatings (e.g., processability improvers, antioxidants, UV absorbers, antistatic agents, fillers, flame retardants, lubricants, antifungal agents, antifouling agents, colorants), but it is preferable that the paint consists only of particles (A). The content of particles (A) in this paint is preferably 98% by mass or more, more preferably 99% by mass or more, and preferably 100% by mass or less. When the content of particle (A) is within the aforementioned range, a resin film with a low coefficient of dynamic friction can be easily formed.

[0025] This paint is preferably used as a powder coating for powder coating applications. In particular, it is preferably used as a powder coating for corona electrostatic powder coating applications. Corona-charging powder coating is a coating method that uses an electrostatic powder coating machine with a corona charging system. In this method, a high voltage is applied to the corona electrode at the tip of the electrostatic gun, causing a corona discharge from the electrode. This discharge charges the powder coating, which then adheres to the surface of the object to be coated (substrate).

[0026] [Ethylene-based polymer particles (particle (A))] Particle (A) is not particularly limited as long as it satisfies the following requirements (I) to (II). This paint may use one type of particle (A), or it may use two or more types of particles (A) that have different physical properties and / or shapes.

[0027] Requirement (I): The intrinsic viscosity [η] measured in decalin at 135°C is 5 to 50 dL / g. The intrinsic viscosity [η] is preferably 5 to 15 dL / g, more preferably 10 to 15 dL / g. When the intrinsic viscosity [η] is within the aforementioned range, a resin film with superior sliding properties and durability can be easily formed. On the other hand, if the intrinsic viscosity [η] exceeds 50 dl / g, the productivity of this coating may decrease. The intrinsic viscosity [η] can be measured specifically by the method described in the following examples.

[0028] Requirement (II): The average particle size d50 is 1 to 500 μm. The average particle size d50 is preferably 1 to 200 μm, more preferably 4 to 70 μm, and even more preferably 8 to 40 μm. When the average particle diameter d50 of particle (A) falls within the aforementioned range, it becomes possible to increase the number of particles per unit volume, and the bonding force is improved by increasing the number of contact points between the substrate and particle (A). Furthermore, by using particle (A) with an average particle diameter d50 within the aforementioned range, a resin film with excellent sliding properties (low coefficient of dynamic friction) can be easily formed. The average particle size d50 can be measured specifically by the method described in the following examples.

[0029] Particle (A) preferably satisfies the following requirement (III) in addition to the requirements (I) to (II) above. Requirement (III): The MFR measured under conditions of 190°C and a test load of 21.6 kg, in accordance with JIS K 7210-1:2014, is 0.001 to 0.5 g / 10 min. The MFR is preferably 0.01 to 0.5 g / 10 min, more preferably 0.01 to 0.05 g / 10 min. Particles (A) with an MFR within the aforementioned range become less prone to melting and flowing, and can maintain their particle shape. As a result, it becomes possible to effectively create irregularities originating from the particles (A) in the resin film obtained using the particles (A).

[0030] Examples of ethylene-based polymers include polymers containing 90 to 100 mol% of structural units derived from ethylene and 0 to 10 mol% of structural units derived from one or more monomers selected from α-olefins having 3 to 6 carbon atoms, and it is preferable that they are homopolymers of ethylene.

[0031] Particles (A) can be produced using known methods, but it is preferable to produce them using the method described in International Publication No. 2006 / 54696, for example. According to the method described in this document, it is considered easy to form a catalyst component with a small particle size and a narrow particle size distribution, and furthermore, by performing polymerization of olefins using this catalyst, it is suitable for producing particles (A) with a small particle size and a narrow particle size distribution.

[0032] Furthermore, particles (A) can also be obtained by crushing an existing olefin polymer and, if necessary, classifying it, in addition to the method described above. However, since existing olefin polymers have a high degree of crystallinity and a dense crystalline structure, especially if their intrinsic viscosity [η] is high, obtaining particles (A) may require a relatively large amount of energy for the crushing process.

[0033] The particles (A) may also contain additives such as pigments and stabilizers.

[0034] ≪Laminates and Methods for Manufacturing Laminates≫ The laminate according to the present invention comprises a substrate and the resin film. The laminate is preferably manufactured by a method that includes a coating step of applying the paint to the surface of a substrate, preferably by powder coating, and more preferably by corona charging powder coating, and a step of baking the powder coating applied to the substrate to form a resin film (baked body) on the substrate.

[0035] The aforementioned substrate is not particularly limited and may be any member on which a resin film obtained from this coating is to be formed. It is preferably a substrate used in applications where sliding properties are required, more preferably a metal substrate or a rubber substrate, and particularly preferably a metal substrate. Examples of the aforementioned metal substrate include stainless steel (SUS), iron steel, and aluminum steel. The rubber used in the rubber substrate may be natural rubber (NR) or synthetic rubber. Specific examples of synthetic rubber include ethylene-propylene copolymer rubber (EPR), ethylene-propylene-diene copolymer rubber (EPDM), chloroprene rubber, silicone rubber, and polyurethane rubber.

[0036] The aforementioned coating process is preferably carried out in such a way that the thickness of the formed resin film (baked body) is preferably 20 to 200 μm, more preferably 20 to 150 μm.

[0037] The conditions for the aforementioned coating are not particularly limited as long as a resin film can be formed on the desired substrate. For example, when performing corona-charging powder coating, the applied voltage is preferably 50 to 120 kV, more preferably 70 to 100 kV, from the standpoint of excellent coating efficiency (the proportion of the coating that adheres to the object to be coated).

[0038] The conditions for the baking process are not particularly limited as long as a resin film can be formed on the desired substrate. However, conditions under an air atmosphere that satisfy the following formula (1) are preferred, as these conditions tend to easily form a resin film with a developed interface area ratio (Sdr) within the above range, a large water wetting contact angle, and excellent water repellency. Baking temperature (°C) + 0.65 × baking time (minutes) < 200 ···(1)

[0039] The aforementioned "baking temperature (°C) + 0.65 × baking time (minutes)" is preferably 197 or less, more preferably 195 or less, even more preferably 190 or less, and particularly preferably 185 or less. The aforementioned "baking temperature (°C) + 0.65 × baking time (minutes)" is preferably 100 or more, more preferably 150 or more, and even more preferably 160 or more.

[0040] The baking temperature is preferably a temperature that satisfies formula (1), and specifically, preferably 140°C or higher, more preferably 150°C or higher, less than 200°C, and preferably 190°C or lower. The baking time is preferably a time that satisfies formula (1), and although it depends on the baking temperature, it is specifically preferably 5 to 60 minutes, more preferably 10 to 50 minutes.

[0041] The aforementioned air atmosphere is not particularly limited as long as it is an atmosphere containing air. For the same reasons as above, it is preferable to perform the baking in air and under conditions that satisfy formula (1).

[0042] This resin film can be used as an alternative material to fluorine coating in applications where fluorine coating is required, and is preferably used in applications where the aforementioned metal is used as the substrate. Applications for this resin film and the laminate include, for example, applications involving a substrate (especially a metal substrate) that has been given liquid-repellent properties. Specifically, these include packaging materials for food, pharmaceuticals, cosmetics, chemical products (including detergents), lubricants, etc. (e.g., containers), toiletries, manufacturing equipment, sliding parts, transport rails, pots, funnels, mesh, piping, etc. Furthermore, the laminate can also be used as a wiper blade, a window wiper for various transportation equipment such as trains and aircraft, a portable wiper (hand wiper) for cleaning glass windows, a sliding material for glass run channels in automobiles, and so on. [Examples]

[0043] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0044] <Intrinsic viscosity [η]> The intrinsic viscosity [η] of ethylene polymer particles was measured at 135°C in decalin solvent.

[0045] <Average particle diameter d50> If the average particle diameter d50 of ethylene polymer particles is 100 μm or less, the mass-based particle size distribution is measured using a particle size distribution analyzer ("Coulter Counter Multisizer 4e", manufactured by Beckmann), and the particle diameter at which the mass accumulation in the mass-based particle size distribution reaches 50% is defined as the average particle diameter d50. If the average particle size d50 of the ethylene polymer particles exceeded 100 μm, the mass of particles remaining on each sieve (unpassed particles) was calculated using sieves with different mesh sizes. From the calculated data, a cumulative distribution (cumulative unpassed particles (%) / sieve mesh size (μm)) was plotted, and the sieve mesh size at which the unpassed particles accounted for 50% by mass was defined as the average particle size d50 of the ethylene polymer particles.

[0046] <mfr> The MFR of ethylene polymer particles was measured in accordance with JIS K 7210-1:2014 under conditions of 190°C and a test load of 21.6 kg.

[0047] <Ethylene-based polymer particles (A-1)> Ultra-high molecular weight ethylene polymer fine particles (Miperon PM-200, manufactured by Mitsui Chemicals, Inc.) were used as ethylene polymer particles (A-1). The physical properties of the ethylene polymer particles (A-1) are as follows. Intrinsic viscosity [η]=13.0dL / g Average particle diameter d50=12.0μm MFR (190℃, 21.6kg load) = 0.020g / 10min

[0048] <Ethylene-based polymer particles (A-2)> Ultra-high molecular weight ethylene polymer fine particles (Mipelon XM-220, manufactured by Mitsui Chemicals, Inc.) were used as ethylene polymer particles (A-2). The physical properties of the ethylene polymer particles (A-2) are as follows. Intrinsic viscosity [η]=14.4dL / g Average particle diameter d50=33.0μm MFR (190℃, 21.6kg load) = 0.015g / 10min

[0049] [Example 1] Ethylene-based polymer particles (A-1) were used as the powder coating. Using a corona-charging electrostatic powder coating machine (Gx8500αK, manufactured by Parker Engineering Co., Ltd.), powder coating was applied to a SUS sheet at a voltage of 100kV so that the resin film thickness obtained from the powder coating was 100μm. The SUS sheet coated with the powder coating was placed in an oven and baked in air at 150°C for 30 minutes, then allowed to cool to room temperature to form a laminate (resin-coated SUS sheet). SEM images of the resin film surface in the formed laminate were obtained using a JSM-6510LV (acceleration voltage 5kV) manufactured by JEOL Ltd. The obtained SEM images are shown in Figure 1.

[0050] [Example 2] In Example 1, the laminate was formed in the same manner as in Example 1, except that the baking time was changed to 60 minutes.

[0051] [Example 3] In Example 1, the laminate was formed in the same manner as in Example 1, except that the baking conditions were changed to 170°C for 10 minutes.

[0052] [Example 4] In Example 1, the laminate was formed in the same manner as in Example 1, except that the baking conditions were changed to 170°C for 20 minutes. SEM images of the resin film surface in the formed laminate were obtained in the same manner as in Example 1. The obtained SEM images are shown in Figure 2.

[0053] [Example 5] In Example 1, the laminate was formed in the same manner as in Example 1, except that the baking conditions were changed to 170°C for 30 minutes.

[0054] [Example 6] In Example 1, the laminate was formed in the same manner as in Example 1, except that the baking conditions were changed to 170°C for 45 minutes.

[0055] [Example 7] In Example 1, the laminate was formed in the same manner as in Example 1, except that the baking conditions were changed to 190°C for 10 minutes. SEM images of the resin film surface in the formed laminate were obtained in the same manner as in Example 1. The obtained SEM images are shown in Figure 3.

[0056] [Example 8] Ethylene-based polymer particles (A-2) were used as the powder coating. Using a corona-charging electrostatic powder coating machine (Gx8500αK, manufactured by Parker Engineering Co., Ltd.), powder coating was applied to a SUS sheet at a voltage of 100kV so that the resin film thickness obtained from the powder coating was 100μm. The SUS sheet coated with the powder coating was placed in an oven and baked in air at 170°C for 30 minutes, then allowed to cool to room temperature to form a laminate (resin-coated SUS sheet).

[0057] [Example 9] In Example 8, the laminate was formed in the same manner as in Example 8, except that the baking time was changed to 45 minutes.

[0058] [Comparative Example 1] In Example 1, the laminate was formed in the same manner as in Example 1, except that the baking conditions were changed to 170°C for 60 minutes. SEM images of the resin film surface in the formed laminate were obtained in the same manner as in Example 1. The obtained SEM images are shown in Figure 4.

[0059] [Comparative Example 2] In Example 1, the laminate was formed in the same manner as in Example 1, except that the baking conditions were changed to 190°C for 20 minutes. SEM images of the resin film surface in the formed laminate were obtained in the same manner as in Example 1. The obtained SEM images are shown in Figure 5.

[0060] [Comparative Example 3] In Example 1, the laminate was formed in the same manner as in Example 1, except that the baking conditions were changed to 190°C for 30 minutes.

[0061] [Comparative Example 4] In Example 8, the laminate was formed in the same manner as in Example 8, except that the baking time was changed to 60 minutes.

[0062] <Formula (1)> In each example and comparative example, the value of "baking temperature (°C) + 0.65 × baking time (minutes)" when forming the laminate is shown in Table 1 as the value of formula (1).

[0063] <Developed interface area ratio (Sdr)> Using a confocal laser microscope (LEXT OLS5100, manufactured by Evident Co., Ltd.), a 960 μm square area of ​​the resin film surface in the formed laminate was measured, and the unfolded interface area ratio (Sdr) was determined in accordance with ISO 25178-2:2012. The results are shown in Table 1.

[0064] <Water wetting contact angle of resin film> Using an image processing-based solid-liquid interface analysis system (DropMaster500, manufactured by Kyowa Interface Science Co., Ltd.), 1.5 μL of distilled water was dropped onto the resin film surface of a laminate at the ambient temperature of 23°C. The contact angle (°) of the water was determined after holding it for 10 seconds. The results are shown in Table 1.

[0065] <Coefficient of dynamic friction of resin film> Using a Gakushin abrasion tester (TRIBOGEAR TYPE31, manufactured by Shinto Kagaku Co., Ltd.), the frictional force was measured for one to three reciprocating passes by bringing the resin film surface of the laminate into contact with a glass plate (30 mm x 30 mm x 6 mm thick), and the coefficient of dynamic friction was calculated. The test conditions were: load: 1 kg, speed: 1 mm / sec, stroke: 80 mm, and ambient temperature: 23 °C. The results are shown in Table 1.

[0066] [Table 1] < / mfr>

Claims

1. A resin film formed from a powder coating containing ethylene polymer particles that satisfy the following requirements (I) and (II), and that satisfies the following requirement (i). (I) The intrinsic viscosity [η] measured in decalin at 135°C is 5 to 50 dL / g. (II) The average particle size d50 is 1 to 500 μm. (i) The unfolded surface area ratio (Sdr) of the resin film surface is 30% or more.

2. The resin film according to claim 1, wherein the unfolded interface area ratio (Sdr) is 80% or more.

3. The resin film according to claim 1, wherein the particle size d50 of the ethylene polymer particles is 1 to 200 μm.

4. The resin film according to claim 1, wherein the intrinsic viscosity [η] of the ethylene polymer particles is 5 to 15 dL / g.

5. A laminate comprising a base material and a resin film according to any one of claims 1 to 4.

6. The laminate according to claim 5, wherein the substrate is metal.

7. A process of coating a substrate with a powder coating containing ethylene polymer particles that meet the following requirements (I) and (II), A step of forming a resin film on a substrate by baking the powder coating applied to the substrate under conditions that satisfy the following formula (1) and in an air atmosphere, including, A method for manufacturing laminates. (I) The intrinsic viscosity [η] measured in decalin at 135°C is 5 to 50 dL / g. (II) The average particle size d50 is 1 to 500 μm. Baking temperature (°C) + 0.65 × baking time (minutes) < 200 ... (1)

8. The manufacturing method according to claim 7, wherein the substrate is a metal.

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