Method for running accelerated weather resistance test and paste used for the same

Abstract

To provide a method for running an accelerated weather resistance test on a polymer material, the method being highly reproducible and reducing the time of the test.SOLUTION: The method for running an accelerated weather resistance test of a polymer material includes: a first step of applying a paste containing a load substance and water on the surface of a polymer material to be a sample, and fixing the load substance in the surface of the sample; washing the sample and removing the paste from the surface; and a third step of radiating light to the sample, the load substance including a layered clay mineral and the paste presenting acidity.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an accelerated weathering test method and a paste for the accelerated weathering test method used therefor.

Background Art

[0002] Polymeric materials such as polymeric coatings are used for the purpose of imparting various properties to an object to be coated, such as antifouling property, waterproof property, rustproof property, corrosion resistance, scratch resistance, fire resistance, heat resistance, chemical resistance, weather resistance and the like. Further, the objects to be coated also cover a wide variety, such as metals, resins, carbon materials, ceramics and the like.

[0003] The polymeric material applied to the object to be coated gradually deteriorates under the actual use environment. Such deterioration is particularly remarkable when used outdoors, and is caused by heat and ultraviolet rays from sunlight, pollutants in the atmosphere and the like.

[0004] As methods for knowing the deterioration of the performance of polymeric materials, that is, how various properties change from the initial state, there are outdoor exposure tests and market records. However, these require a long test period of one year.

[0005] Therefore, for the purpose of shortening the test time, methods using various accelerated weathering test machines have also been adopted. However, the methods using these test machines are difficult to completely reproduce the deterioration of polymeric materials under the actual use environment.

[0006] On the other hand, Patent Document 1 discloses a method in which a test aqueous solution containing nitrate ions at a specific concentration is adhered to the surface of a coating material and irradiated with light having a specific illuminance in the ultraviolet region. Further, Patent Document 2 discloses a method in which a sample having a deliquescent inorganic salt adhered to the surface is subjected to an accelerated weathering test under temperature and humidity conditions in a tank at a certain relative humidity or higher.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, neither of the methods described in Patent Documents 1 and 2 can still cover all the factors causing deterioration in the actual use environment, and the market reproducibility is low. In addition, such an accelerated weather resistance testing machine is very costly, such as electricity costs, because a test time of a certain length or more is required.

[0009] Therefore, an object of the present invention is to provide an accelerated weather resistance testing method for polymer materials with extremely high market reproducibility and capable of shortening the test time. Another object is to provide a paste with extremely high market reproducibility and high accelerating properties for use in the above accelerated weather resistance test.

Means for Solving the Problems

[0010] As a result of intensive studies, the present inventor has found that the above problems can be solved by using a paste containing a layered clay mineral as a loading substance, and has thus completed the present invention.

[0011] That is, the gist of the present invention is as follows. [1] An accelerated weather resistance testing method for polymer materials, comprising: a first step of applying a paste containing a loading substance and water to the surface of a polymer material to be a sample, and fixing the loading substance to the surface of the sample; a second step of washing the sample and removing the paste from its surface; and a third step of irradiating the sample with light, in this order, to perform a cycle, wherein the loading substance contains a layered clay mineral, and the paste shows acidity, an accelerated weather resistance testing method. [2] The method for accelerating weather resistance test according to [1], wherein the paste contains a clay pigment as a loading substance containing the layered clay mineral. [3] The method for accelerating weather resistance test according to [1] or [2], wherein the loading substance further contains an inorganic salt. [4] The method for accelerating weather resistance test according to [3], wherein the inorganic salt contains at least one selected from the group consisting of sodium salts, magnesium salts, potassium salts, calcium salts, and ammonium salts. [5] The cycle includes a preparation step of preparing the paste before the first step. The method for accelerating weather resistance test according to any one of [1] to [4], wherein in the preparation step, the acidity of the paste is adjusted. [6] The loading substance further contains an inorganic salt. The method for accelerating weather resistance test according to [5], wherein the acidity is adjusted by adjusting the concentration of the inorganic salt. [7] The method for accelerating weather resistance test according to [5], wherein the acidity is adjusted by introducing an acid. [8] The method for accelerating weather resistance test according to any one of [1] to [7], wherein the loading substance further contains at least one selected from the group consisting of carbon-based dust, SiO2, Fe2O3, Al2O3, CaO, MgO, and TiO2. [9] The method for accelerating weather resistance test according to any one of [1] to [8], wherein in the first step, after applying the paste, by heating, at least one of the acid component and the ionic component in the paste showing acidity is permeated into the sample.

[10] The method for accelerating weather resistance test according to any one of [1] to [9], wherein the light irradiation in the third step is performed while spraying hydrogen peroxide solution.

[11] The method for accelerating weather resistance test according to any one of [1] to

[10] , wherein the light irradiation in the third step is performed using a sunshine carbon arc, an ultraviolet carbon arc, a metal halide arc lamp, a xenon arc lamp, an ultraviolet fluorescent lamp, or an ultraviolet fluorescent lamp xenon lamp.

[12] The accelerated weathering test method according to any one of [1] to

[11] above, which repeats the cycle a plurality of times.

[0012]

[13] In the accelerated weathering test of a polymer material, a paste used as a loading factor, The paste contains a layered clay mineral and water, and shows acidity, and is a paste for an accelerated weathering test.

[14] The paste according to

[13] above, which further contains an inorganic salt.

Advantages of the Invention

[0013] The accelerated weathering test method according to the present invention can achieve extremely high market reproducibility. As a result, it becomes possible to customize tests according to the actual use environment of polymer materials, provide appropriate feedback for material development, and improve the predictability of market troubles. In addition, since the accelerated weathering test method according to the present invention can evaluate weather resistance in a shorter test time than before, it becomes possible to reduce the environmental load, reduce costs such as electricity charges, and create surplus time.

[0014] The paste for an accelerated weathering test according to the present invention has high market reproducibility and high acceleration property, so that the accelerated weathering test of a polymer material can be carried out with extremely high market reproducibility in a shorter time than before.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0016] 《Accelerated Weathering Test Method》 The accelerated weathering test method according to this embodiment performs a cycle including the following steps in order. First step: A step of applying a paste containing a loading substance and water to the surface of the polymer material to be the sample and fixing the attachment substance on the surface of the sample. Second step: A step of washing the sample and removing the paste from its surface. Third step: A step of irradiating the sample with light.

[0017] The cycle in the accelerated weathering test method according to this embodiment may include the following preparation step before the first step in addition to the first to third steps. Preparation step: A step of preparing a paste whose acidity has been adjusted.

[0018] Hereinafter, each step will be described in order.

[0019] 〈Preparation Step〉 The preparation process in this embodiment is a process of preparing a paste, which is optional. In the above process, the acidity of the paste is adjusted. That is, the paste may be acidic, but if desired, its acidity may be adjusted.

[0020] As a method for adjusting the acidity, when an inorganic salt is included in addition to the layered clay mineral as a loading substance, a method of adjusting the concentration of the inorganic salt can be mentioned. This is what the inventor has found through research that when the paste contains a layered clay mineral and an inorganic salt as loading substances, the paste becomes acidic due to their reaction.

[0021] In this case, the paste can be made acidic without separately introducing an acid into the paste, and further, by adjusting the concentration of the inorganic salt, it can also be adjusted to a desired pH. However, the above does not exclude at all adjusting the acidity by using other means such as further separately introducing an acid to adjust the acidity even when the loading substance contains an inorganic salt.

[0022] That is, the acidity of the paste can be adjusted, for example, in addition to the above concentration adjustment of the inorganic salt, or together with the concentration adjustment of the inorganic salt, by introducing an acid. Examples of the acid to be introduced include sulfuric acid, hydrochloric acid, nitric acid, acetic acid, etc.

[0023] The pH of the paste also varies depending on the environment to be reproduced. For a general exposure site, an acidity of pH 3 - 5 is suitable, but in a polluted environment such as an industrial area or along a trunk road where the exposure is severe, a strong acidity of pH 1 - 3 is suitable. On the other hand, in a dry area with little rainfall or a sparsely populated exposure site, a weak acidity of pH 5 - 6 is suitable. Note that the pH of the paste in this specification is a value measured using a pH meter. When the viscosity of the paste is too high to be measured with a pH meter, the viscosity of the paste is appropriately adjusted using pure water, and then the measurement is performed with a pH meter.

[0024] 〈First Step〉 The first step in this embodiment is a step of applying a paste containing a loading substance and water to the surface of a polymer material serving as a sample, and fixing the loading substance to the surface of the sample.

[0025] The paste in this embodiment contains a loading substance and water and exhibits acidity. The loading substance contains a layered clay mineral, and the layered clay mineral is a substance classified as a pseudo-pollutant among the loading substances.

[0026] The loading substance containing the layered clay mineral, which is a pseudo-pollutant, is fixed to the surface of the sample because it is in paste form. As a result, even after the sample is washed in the second step, the state where the loading substance is fixed to the sample surface is maintained. Although the reason for this is not clear, it is thought that because the loading substance is in paste form, the loading substance is fixed to the sample surface at the molecular level. As a result, the degree of progress of sample deterioration when irradiated with light in the third step can be reproduced in a state closer to the actual use environment than in the conventional test method, enabling an accelerated weather resistance test with high market reproducibility. Furthermore, by making the paste acidic, higher market reproducibility can also be achieved for the deterioration due to acid hydrolysis of the polymer material. Note that the deterioration due to acid hydrolysis is further enhanced in market reproducibility by allowing the acid component and ionic component of the paste to penetrate into the interior of the polymer material. Details will be described later. As an index of the degree of progress of deterioration of the polymer material, there is a change in the glossiness of the sample, that is, the gloss retention rate.

[0027] Among the loading substances, the layered clay mineral is generally a layered silicate, and has a basic structure in which a tetrahedral sheet in which (Si,Al)O4 tetrahedrons are two-dimensionally bonded and an octahedral sheet in which M(O,OH)6 (M = Al, Mg, Fe, Ti, etc.) octahedrons are two-dimensionally networked share some O ions to form a layered structure.

[0028] Examples of the loading substance containing a layered clay mineral include clay pigments. Examples of clay minerals contained in clay pigments include kaolinite, bentonite, montmorillonite, illite, smectite, vermiculite, pyrophyllite, halloysite, sericite, and the like.

[0029] Examples of clay pigments include the ASP (registered trademark) series, Satintone (registered trademark) series, Translink (registered trademark) series, Mattex (registered trademark), Buca (registered trademark) manufactured by BASF, the Garamite series manufactured by Southern Clay Products, the Optiwhite series manufactured by BURGESS PIGMENT, the wax stone clay series manufactured by Maruo Calcium, the Hardtop Clay manufactured by Shiraishi Calcium, and the like.

[0030] As a loading substance containing a layered clay mineral, other than clay pigments, those containing a layered silicate mineral are not particularly limited and can be adopted as long as they contain at least one of the pigments contained in the clay pigment. For example, other pigments containing at least one of the pigments contained in the clay pigment can be mentioned.

[0031] The preferred range of the total content ratio of the above-mentioned layered clay minerals with respect to the total amount of solids in the paste is not particularly limited because it varies depending on the environment of the exposure site to be reproduced. The total content ratio is preferably, for example, 10 to 100% by mass, may be 30 to 95% by mass, or may be 50 to 95% by mass. Here, from the viewpoint of paintability, the content ratio is preferably 10% by mass or more, may be 30% by mass or more, or may be 50% by mass or more. Also, the content ratio may be 100% by mass, that is, the total amount of solids in the paste may be a layered clay mineral, but in accordance with the environment of the exposure site, other components such as inorganic salts are also contained, and from the viewpoint of enhancing market reproducibility, the content ratio is preferably 95% by mass or less.

[0032] The loading substance may further contain an inorganic salt. Inorganic salts are substances classified as pseudo-corrosive substances among the loading substances, and from the viewpoint of approaching the actual environment, it is preferable for the loading substance to contain an inorganic salt. In addition to the above, when the method according to the present embodiment includes a preparation step of preparing a paste whose acidity has been adjusted before the first step, as described above, the acidity of the paste may be adjusted by adjusting the concentration of the inorganic salt in the loading substance.

[0033] When the acid hydrolysis of the polymer material of the sample is promoted by the presence of the layered clay mineral and the inorganic salt, the hydrophilicity of the polymer material is promoted, the internal stress increases, and the film thinning can be promoted. As a result, the accelerated weathering test time is further shortened.

[0034] When the loading substance further contains an inorganic salt, the inorganic salt preferably contains at least one selected from the group consisting of sodium salts, magnesium salts, potassium salts, calcium salts, and ammonium salts. The anion component of the above various salts is Cl - , NO3 - , SO4 2- is preferred.

[0035] That is, the inorganic salt preferably contains at least one selected from the group consisting of sodium chloride, magnesium chloride, potassium chloride, calcium chloride, ammonium chloride, sodium nitrate, magnesium nitrate, potassium nitrate, calcium nitrate, ammonium nitrate, sodium sulfate, magnesium sulfate, potassium sulfate, calcium sulfate, ammonium sulfate, and sodium sulfate, and more preferably contains at least one of sodium chloride, magnesium chloride, and magnesium nitrate. Furthermore, since chloride ions are components that promote photo-degradation, the inorganic salt more preferably contains at least one selected from the group consisting of sodium chloride, magnesium chloride, potassium chloride, calcium chloride, and ammonium chloride, and even more preferably contains at least one of sodium chloride and magnesium chloride.

[0036] The inorganic salt may further contain other inorganic salts other than those described above. Examples of other inorganic salts include strontium, iron, zinc, copper, manganese, lithium, etc. as cation components. Also, as anion components, CO 3- , NO2 - , SO3 2- , F - , Br - and the like.

[0037] The total proportion of sodium salt, magnesium salt, potassium salt, calcium salt, and ammonium salt in the inorganic salt is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and may be 90 to 99% by mass. Here, from the viewpoint of market reproducibility, the above proportion is preferably 50% by mass or more, more preferably 70% by mass or more, and may be 90% by mass or more. Also, the above proportion may be 100% by mass, that is, the total amount of inorganic salts contained in the paste may be sodium salt, magnesium salt, potassium salt, calcium salt, and ammonium salt. However, depending on the environment of the exposure site, it may be appropriate to include other salts, and in this case, the total content may be less than 100% by mass, or may be 99% by mass or less.

[0038] The total content ratio of the above inorganic salts to the total amount of solid content in the paste is not particularly limited because it varies depending on the environment of the exposure site to be reproduced. Examples of the total content ratio include 0 to 10% by mass, may be more than 0% by mass and less than 10% by mass, and may be 0.1 to 8% by mass. Here, the total content ratio may be 0% by mass, that is, it may not contain inorganic salts. However, when it contains, it may be 0.1% by mass or more. Also, the upper limit of the total content ratio is not particularly limited, but for example, it may be 10% by mass or less, may be less than 10% by mass, and may be 8% by mass or less.

[0039] The paste in this embodiment may further contain at least one other component selected from the group consisting of carbon-based dust, SiO2, Fe2O3, Al2O3, CaO, MgO, and TiO2 as a loading substance. These are components that are likely to be contained in the air in urban areas, or components contained in volcanic ash, and like the layered clay minerals, are components that reduce the gloss retention rate of the sample. Examples of the other components include one to twelve types, fifteen to seventeen types, etc. of JIS dust conforming to JIS Z 8901:2006. Among them, although it varies depending on the environment of the exposure site to be reproduced, seven types, eight types, and eleven types of the above JIS dust are preferable, and eight types and eleven types are more preferable. Also, examples of carbon-based dust include carbon ash and the like.

[0040] The total content ratio of the other components with respect to the total amount of the solid content in the paste is preferably 0 to 90% by mass, more preferably 5 to 70% by mass, and even more preferably 5 to 50% by mass. Here, it may not contain the other components, but when it contains them, from the viewpoint of suitably obtaining the effects of the other components, the content ratio is preferably 5% by mass or more. Also, from the viewpoint of suitably obtaining the effects of components such as layered clay minerals, the content ratio is preferably 90% by mass or less, more preferably 70% by mass or less, and even more preferably 50% by mass or less.

[0041] The paste in this embodiment contains the above load substance and water, but may further contain other substances as long as the effects of the present invention are not impaired. Examples of the other substances include acid components used for adjusting the acidity of the paste in the preparation process.

[0042] The paste in this embodiment shows acidity, which makes it easier for the load substance to adhere to the surface of the polymer material and promotes the acid hydrolysis of the polymer material. As a result, the hydrophilicity of the polymer material is promoted, the internal stress increases, and the film reduction can be promoted, so that the accelerated weathering test time can be further shortened.

[0043] The solid content concentration of the paste in this embodiment is not particularly limited. For example, 10 to 70% by mass is preferable, 20 to 60% by mass is more preferable, and 25 to 50% by mass is even more preferable. Here, from the viewpoint of preventing the paste from flowing down after being applied to the surface of the polymer material, the solid content concentration is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more. Further, from the viewpoint of the smoothness of the applied paste, the solid content concentration is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0044] The viscosity of the paste is not particularly limited and varies depending on the coating method. For example, in the case of spray coating, the viscosity at 23°C is preferably 0.1 to 10 Pa·s, more preferably 0.5 to 8 Pa·s, and even more preferably 1 to 5 Pa·s. Here, from the viewpoint of preventing the paste from flowing down after being applied to the surface of the polymer material, the viscosity of the paste is preferably 0.1 Pa·s or more, more preferably 0.5 Pa·s or more, and even more preferably 1 Pa·s or more. Further, from the viewpoint of the smoothness of the applied paste, the viscosity is preferably 10 Pa·s or less, more preferably 8 Pa·s or less, and even more preferably 5 Pa·s or less. Note that the viscosity of the paste in this specification means the rotational viscosity at 60 revolutions using a B-type viscometer.

[0045] The method of applying the paste to the surface of the polymer material is not particularly limited. For example, application using a brush, dip coating, printing, coating with a bar coater, spray coating, etc. can be mentioned.

[0046] After applying the paste in this embodiment to the surface of the polymer material, it is preferable to heat it. Thereby, the acid component and ionic component in the paste showing acidity can be more suitably penetrated into the interior of the polymer material. Thereby, the hydrophilization and acid hydrolysis of the polymer material are promoted, and the market reproducibility is further improved. For example, when the actual use environment of the polymer material as a sample exceeds 40°C, the market reproducibility can be further enhanced by heating to a temperature comparable to the actual use environment.

[0047] In the first step of this embodiment, it was found that after applying a paste to the surface of a polymer material and then drying it, a loading substance can be fixed to the surface. It is considered that the cohesive force of the loading substance contributes to this during the drying process of the paste. Further, the above fixation can be made stronger by further heating after applying the paste. It is considered that the plastic flow of the applied paste contributes to this by heating. On the other hand, when the loading substance is an aqueous solution rather than a paste, even if the surface of the sample can be altered, the adherent substance cannot be fixed, or if it can be fixed, it is insufficient, so the market reproducibility is poor.

[0048] The drying method of the paste applied to the surface of the polymer material is not particularly limited, and natural drying, heating drying, reduced-pressure drying, heating reduced-pressure drying, etc. can be adopted. For example, heating is preferable from the viewpoint of making the fixation of the loading substance strong, heating drying or heating reduced-pressure drying is preferable, and heating drying is more preferable.

[0049] Among them, when heating such as heat drying or heat reduced-pressure drying is performed, it may also combine the penetration of the acid component or ionic component in the paste and drying.

[0050] <Second step> The second step in this embodiment is a step of washing the sample and removing the paste from its surface.

[0051] If dust, dirt, stains, etc. enter the inside of the accelerated weathering tester, it will lead to the failure and short life of the tester. Therefore, in the second step, in the accelerated weathering tester, when water is sprayed on the sample, washing is performed to such an extent that the contaminated dust does not flow out. Thereby, the constituent components of the paste other than the loading substance fixed to the sample surface at the molecular level are removed from the surface of the polymer material.

[0052] Specifically, methods such as washing with running water or using running water and further scrubbing the surface of the polymer material with a sponge or gauze can be adopted. After washing, after appropriately draining and drying, the sample is provided to the subsequent third step.

[0053] 〈Third Step〉 The third step in this embodiment is a step of irradiating the sample with light. By irradiating with light, the polymer material as the sample is photo-degraded.

[0054] For the irradiation with light, conventionally known ones can be adopted, and it also varies depending on the accelerated weathering tester used. Specifically, for example, a sunshine carbon arc, an ultraviolet carbon arc, a metal halide arc lamp, a xenon arc lamp, an ultraviolet fluorescent lamp, or an ultraviolet fluorescent lamp xenon lamp can be used. According to the actual usage environment to be reproduced, the type of light, illuminance, etc. can be appropriately determined. Also, if necessary, irradiation with light may be performed under a dew condensation state by spraying water or using a humidifier, etc.

[0055] Irradiation with light may be performed while spraying hydrogen peroxide solution. Generally, inside the accelerated weathering tester, since the ratio of oxygen to light is lower due to the higher illuminance of light compared to the actual usage environment, it is considered that the photo-oxidation reaction is less likely to occur. In contrast, it has been found that by introducing hydrogen peroxide solution, oxygen is generated by light irradiation, and this promotes the photo-oxidation reaction of the polymer material, making it possible to approach the actual usage environment.

[0056] In the accelerated weathering test method according to this embodiment, the above first step to third step are taken as one cycle, and the cycle may be repeated a plurality of times. When a preparation step is included before the first step, the preparation step to third step are taken as one cycle, and the cycle may be repeated a plurality of times. When repeating the above cycle multiple times, each step is generally performed under the same conditions, but there is no exclusion from adopting different conditions.

[0057] The number of times the above cycle is repeated varies depending on the actual environment to be reproduced and the conditions of each step. However, for example, in the case of outdoor exposure for one year, while the conventional accelerated weathering test required a test time of 2000 hours, the test method according to this embodiment can achieve high market reproducibility in about 900 hours. Thus, the test method according to this embodiment can significantly shorten the test time compared to the conventional test method. This can be said to be the effect of accelerating the deterioration of the coating film due to the pollution load using the loading substance in the first and second steps above. That is, the accelerated weathering test method according to this embodiment is more suitable for the accelerated weathering test that reproduces outdoor exposure with a particularly high pollution load.

[0058] 《Paste for Accelerated Weathering Test》 The paste according to this embodiment is used as a loading factor in the accelerated weathering test of polymer materials. The paste contains a layered clay mineral and water and exhibits acidity. The above paste can adopt the same one as the paste in the above-mentioned 《Accelerated Weathering Test Method》, and the preferred embodiments are also the same. For example, the paste according to this embodiment preferably further contains an inorganic salt in addition to the layered clay mineral and water.

Example

[0059] Hereinafter, the present invention will be described in more detail with reference to examples, reference examples, and comparative examples, but the present invention is not limited thereto.

[0060] 《Example 1》 〈Preparation of Sample〉 On the surface of a degreased and zinc phosphate-treated steel sheet (70 mm × 150 mm × 0.8 mm) conforming to JIS G 3141:2017, cationic electrodeposition paint A was applied and heated at 170 °C for 20 minutes to form an electrodeposition coating film with a film thickness of 20 μm. On the surface of the above electrodeposition coating film, intermediate coating paint B (a polyester resin-melamine resin-based material) was electrostatically coated and heated at 140 °C for 30 minutes to form an intermediate coating film with a film thickness of 35 μm. Finally, topcoat base coat paint C (an acrylic resin-melamine resin-based material) and topcoat clear coat paint D (an acrylic resin-melamine resin-based material) were applied in a wet-on-wet manner on the surface of the above intermediate coating film and heated at 140 °C for 30 minutes to form a topcoat film with a topcoat base coat film thickness of 15 μm and a topcoat clear coat film thickness of 40 μm, and this was used as a sample.

[0061] 〈First step〉 As loading substances, clay pigment (kaolin, manufactured by BASF, ASP200), 8 types of JIS test powder 1, and inorganic salts were added to water to prepare a paste. The mixing ratio of each component in the paste was ASP200: 8 types of JIS test powder 1: inorganic salts: water = 250:50:7:593 (mass ratio). Also, the above inorganic salts were sodium chloride: magnesium nitrate hexahydrate = 10:90 (mass ratio). The pH of the obtained paste was 4.0, the measured viscosity at 6 rotations of a B-type viscometer at 23 °C was 7.9 Pa·s, and the measured viscosity at 60 rotations was 1.9 Pa·s. The paste obtained above was applied to the sample surface with a brush so that it became 900 g / m 2 and allowed to stand at 50 °C for 20 hours. Thereby, the loading substances were fixed to the sample surface, and the acid components and ionic components in the paste were allowed to penetrate into the sample interior.

[0062] 〈Second step〉 The sample was washed using running water to remove the paste from its surface. Then, it was drained and dried at room temperature.

[0063] 〈Third step〉 Next, the sample was placed in an accelerated weathering tester (manufactured by Suga Test Instruments Co., Ltd., Super Xenon Weather Meter SX-75, attached with a hydrogen peroxide spraying device SX-H2O2), and while spraying hydrogen peroxide water (H2O2), light with a xenon arc lamp as the light source was irradiated. The light irradiation conditions are as follows. · Illuminance at wavelengths of 300 to 400 nm: 60 W / m 2 (Radiant exposure) · Black panel temperature: 63 ± 3°C · Humidity inside the tester: 50 ± 5%RH · For the sample, 1% hydrogen peroxide water was sprayed 15 minutes / 20 hours each time, for a total of 20 times. · Test time: 400 hours (integrated exposure amount 86 MJ / m 2 )

[0064] The above first to third steps were performed 6 cycles to conduct an accelerated weathering test. The total irradiation time of light in the accelerated weathering test was 2400 hours, and the total test time was about 2520 hours.

[0065] 《Example 2》 In the 〈Preparation of Sample〉 of Example 1, as the topcoat film, instead of the topcoat base coat paint C (acrylic resin - melamine resin-based material) and the topcoat clear coat paint D (acrylic resin - melamine resin-based material), a white solid paint E (polyester - melamine resin-based material) was applied and heated at 140°C for 30 minutes to form a topcoat film with a film thickness of 40 μm as the sample. An accelerated weathering test was conducted in the same manner as in Example 1.

[0066] 《Example 3-1》 In the 〈Preparation of Sample〉 of Example 1, as the topcoat film, instead of the topcoat base coat paint C (acrylic resin - melamine resin-based material) and the topcoat clear coat paint D (acrylic resin - melamine resin-based material), a yellow solid paint F-1 (polyester - polyisocyanate resin-based material) was applied and heated at 80°C for 30 minutes to form a topcoat film with a film thickness of 40 μm as the sample. An accelerated weathering test was conducted in the same manner as in Example 1.

[0067] Examples 3-2 to 3-15 Accelerated weather resistance tests were conducted in the same manner as in Example 3-1, except that yellow solid paints F-2 to F-15, in which the hydroxyl value and composition of the polyester resin were varied with respect to the yellow solid paint F-1 of Example 3-1, were prepared and applied. Note that for yellow solid paints F-1 to F-15, the hydroxyl value of the polyester resin was varied from 52 mgKOH / g to 130 mgKOH / g, and the dynamic coating film Tg of the coating film was varied from 50°C to 79°C.

[0068] Example 4 Accelerated weather resistance tests were conducted in the same manner as in Example 1, except that the conditions of <Third Step> in Example 1 were changed as follows. <Third Step>[ The sample was placed in an accelerated weather resistance tester (manufactured by Suga Test Instruments Co., Ltd., Super Xenon Weather Meter SX-75), and irradiated with light using a xenon arc lamp as the light source. The light irradiation conditions are as follows. · Illuminance at wavelengths of 300 to 400 nm: 60 W / m 2 (Radiant exposure) · Black panel temperature: 63 ± 3°C · Humidity inside the tester: 50 ± 5%RH · Test time: 400 hours (integrated exposure amount 86 MJ / m 2 )

[0069] Example 5 Accelerated weather resistance tests were conducted in the same manner as in Example 4, except that the same samples as in Example 2 were used for the samples in Example 4.

[0070] Reference Example 1 The same samples as in Example 1 were placed in an exposure site in the external environment of Okinotorishima, Oshima-gun, Kagoshima Prefecture, and a weather resistance test (under actual use environment) was conducted for 3 years (about 26,300 hours).

[0071] Reference Example 2 The same samples as those in Example 2 were placed at an exposure site in the external environment of Okinoerabu Island, Ōshima District, Kagoshima Prefecture, and a weather resistance test (under actual use conditions) was conducted for 3 years (about 26,300 hours).

[0072] 《Reference Examples 3-1 to 3-15》 The same samples as those in Examples 3-1 to 3-15 were placed at an exposure site in the external environment of Okinoerabu Island, Ōshima District, Kagoshima Prefecture, and a weather resistance test (under actual use conditions) was conducted for 3 years (about 26,300 hours). Note that the same sample numbers in the examples and reference examples mean that the samples are the same.

[0073] 《Comparative Example 1》 Using the same samples as those in Example 1, an accelerated weather resistance test was conducted in accordance with JIS K 5600-7-7:2008. The total time of the accelerated weather resistance test was 6,000 hours.

[0074] 《Comparative Example 2》 An accelerated weather resistance test was conducted in the same manner as Comparative Example 1 for the samples in Comparative Example 1, except that the same samples as those in Example 2 were used.

[0075] 《Comparative Examples 3-1 to 3-15》 An accelerated weather resistance test was conducted in the same manner as Comparative Example 1 for the samples in Comparative Example 1, except that the same samples as those in Examples 3-1 to 3-15 were used. Note that the same sample numbers in the examples and comparative examples mean that the samples are the same.

[0076] 《Evaluation》 〈Composition change〉 For the samples before and after the tests in each of Example 1, Example 4, Reference Example 1, and Comparative Example 1, infrared spectroscopy (IR) analysis (ALPHAII, manufactured by Bruker) using the total reflection measurement method (ATR method) was performed to obtain IR spectra. The IR spectrum of Example 1 is shown in Figure 1, the IR spectrum of Example 4 is shown in Figure 2, the IR spectrum of Reference Example 1 is shown in Figure 3, and the IR spectrum of Comparative Example 1 is shown in Figure 4. In Figures 1 to 4, the dotted line represents the IR spectrum before the test, and the solid line represents the IR spectrum after the test. Also, the enlarged views of the IR spectra in the wavenumber range of 1600 to 1400 cm -1 are also shown in Figures 1 to 4 respectively.

[0077] As a result, in Reference Example 1 under the actual use environment, compared with before the test, the -OH group (around 3400 cm -1 wavenumber) increased, the peroxide (around 1780 cm -1 wavenumber) increased, and the melamine (in the wavenumber range of 1600 to 1450 cm -1 ) decreased. Similarly, in Example 1 and Example 4, compared with before the test, the phenomena of an increase in the -OH group, an increase in the peroxide, and a decrease in the melamine were also observed. On the other hand, in Comparative Example 1 that adopted the conventional accelerated weathering test method, although the phenomena of an increase in the -OH group and an increase in the peroxide were observed, the phenomenon of a decrease in the melamine was not observed. The decrease in melamine was due to the elution of the melamine resin from the topcoat film accompanying the hydrolysis reaction, and it can be seen that the hydrolysis reaction was progressing along with the coating film deterioration in Reference Example 1 under the actual use environment. In Comparative Example 1, this hydrolysis reaction could not be reproduced, but it can be seen that it could be reproduced in Example 1 and Example 4.

[0078] 〈Surface Observation〉 The surface of the sample in each case was observed periodically from the start of the test using a scanning electron microscope (SEM, JSM-5510LV manufactured by JEOL Ltd.). Among the obtained SEM images, the results of Example 2, Example 5, Reference Example 2, and Comparative Example 2 are summarized in FIG. 5. For Example 2 and Example 5, SEM images at 800 hours, 1600 hours, and 2400 hours after the start of the test were shown. For Reference Example 2, SEM images at 1 year, 2 years, and 3 years after the start of the test (start of exposure) were shown. For Comparative Example 2, SEM images at 2000 hours, 4000 hours, and 6000 hours after the start of the test were shown.

[0079] As a result, in Reference Example 2 under the actual use environment, honeycomb-shaped coating film shape deterioration was observed, and this deterioration became more severe with the passage of the exposure time. On the other hand, in the accelerated weather resistance test (Comparative Example 2) compliant with the conventional JIS standard, cracking on the coating film surface and exposure of the titanium oxide pigment due to decomposition and disappearance of the resin component occurred, and it was found that the shape deterioration in the actual use environment could not be reproduced. On the contrary, when using the accelerated weather resistance test method according to the present embodiment, it was found that honeycomb-shaped coating film shape deterioration was observed and an accelerated weather resistance test close to the actual use environment could be realized. This was particularly remarkable in Example 2 where hydrogen peroxide water was sprayed while irradiating light, and the extremely high market reproducibility of the accelerated weather resistance test method according to the present embodiment was confirmed.

[0080] 〈Gloss retention rate〉 Regarding Example 3-1 to Example 3-15 and Comparative Example 3-1 to Comparative Example 3-15, a study was conducted on the correlation with the degree of deterioration of the samples in Reference Example 3-1 to Reference Example 3-15 under the actual use environment. Specifically, for the sample in each case, the 60° specular reflectance (r0) before the test and the 60° specular reflectance (r1) after the test were measured respectively, and the value represented by {(r1 / r0)×100(%)}, that is, the 60° gloss retention rate was obtained.

[0081] Fifteen samples of yellow solid paints F-1 to F-15 have had their hydroxyl value of the polyester resin and the dynamic film Tg of the coating film changed. Therefore, the 60° gloss retention rates when 2 years had passed since the start of the test (start of exposure) in Reference Examples 3-1 to 3-15, which are the actual use environments, were different for each, with a minimum of 33%, a maximum of 63%, and an average of 47%. In contrast, the 60° gloss retention rates after 1600 hours had passed since the start of the accelerated weather resistance test in Examples 3-1 to 3-15 were a minimum of 35%, a maximum of 74%, and an average of 52%. Also, the 60° gloss retention rates after 4000 hours had passed since the start of the accelerated weather resistance test in Comparative Examples 3-1 to 3-15 were a minimum of 15%, a maximum of 84%, and an average of 53%.

[0082] Figure 6 shows a graph indicating the correlation between the 60° gloss retention rate when 2 years had passed since the start of the test (start of exposure) in Reference Examples 3-1 to 3-15, which are the actual use environments, and after 1600 hours had passed since the start of the accelerated weather resistance test in Examples 3-1 to 3-15. The correlation coefficient R2 in this graph was 0.713. In contrast, similarly, Figure 7 shows a graph indicating the correlation between the 60° gloss retention rate when 2 years had passed since the start of the test (start of exposure) in Reference Examples 3-1 to 3-15, which are the actual use environments, and after 4000 hours had passed since the start of the accelerated weather resistance test in Comparative Examples 3-1 to 3-15. The correlation coefficient R2 in this graph was 0.044. From these, it can be said that the accelerated weather resistance test method according to this embodiment has extremely high market reproducibility compared to the conventional method.

[0083] Also, Figure 8 shows the relationship between the test time and the average value of the 60° gloss retention rate in each of the 15 samples of Examples 3-1 to 3-15, Reference Examples 3-1 to 3-15, and Comparative Examples 3-1 to 3-15. Here, the average value of the 60° gloss retention rate means the average value of the 60° gloss retention rate at a predetermined time for each of the 15 samples in the examples, reference examples, and comparative examples. Specifically, for the examples, the average values of the 60° gloss retention rate were determined at 800 hours, 1600 hours, and 2400 hours after the start of the test. For the comparative examples, the average values of the 60° gloss retention rate were determined at 2000 hours, 4000 hours, and 6000 hours after the start of the test. For the reference examples, the average values of the 60° gloss retention rate were determined at 1 year (about 8760 hours), 2 years (about 17520 hours), and 3 years (about 26280 hours) after the start of the test. Also, in FIG. 8, the results of Examples 3-1 to 3-15 are shown as "Example 3", the results of Comparative Examples 3-1 to 3-15 are shown as "Comparative Example 3", and the results of Reference Examples 3-1 to 3-15 are shown as "Reference Example 3". In this graph, when comparing the test times at which the 60° gloss retention rate reaches 50%, the reference example (average of Reference Examples 3-1 to 3-15) under the actual use environment was about 17000 hours (about 2 years), while the example (average of Examples 3-1 to 3-15) was about 1600 hours, and the comparative example (average of Comparative Examples 3-1 to 3-15) was about 4200 hours. There was a difference of about 2.6 times between the example and the comparative example. From these results, it can be said that the accelerated weathering test method according to this embodiment can significantly shorten the test time compared to the conventional method.

Claims

1. A method for accelerating the weather resistance test of a polymer material, comprising: a first step of applying a paste containing a loading substance and water to the surface of the polymer material to be a sample, and fixing the loading substance on the surface of the sample; a second step of washing the sample and removing the paste from its surface; and a third step of irradiating the sample with light, performing a cycle including these steps in order; the loading substance contains a layered clay mineral; the paste shows acidity, the method for accelerating the weather resistance test.

2. The method for accelerating the weather resistance test according to claim 1, wherein the paste contains a clay pigment as the loading substance containing the layered clay mineral.

3. The method for accelerating the weather resistance test according to claim 1 or 2, wherein the loading substance further contains an inorganic salt.

4. The method for accelerating the weather resistance test according to claim 3, wherein the inorganic salt contains at least one selected from the group consisting of sodium salts, magnesium salts, potassium salts, calcium salts, and ammonium salts.

5. The cycle includes a preparation step of preparing the paste before the first step; In the preparation step, the acidity of the paste is adjusted, the method for accelerating the weather resistance test according to claim 1 or 2.

6. The loading substance further contains an inorganic salt; The method for accelerating the weather resistance test according to claim 5, wherein the adjustment of the acidity is performed by adjusting the concentration of the inorganic salt.

7. The method for accelerating the weather resistance test according to claim 5, wherein the adjustment of the acidity is performed by introducing an acid.

8. The load substance further includes at least one selected from the group consisting of carbon dust, SiO ２ , Fe ２ O ３ , Al ２ O ３ , CaO, MgO, and TiO ２ , and the accelerated weather resistance test method according to claim 1 or 2.

9. In the first step, after applying the paste, by heating, at least one of the acid component and the ionic component in the paste showing acidity is penetrated into the interior of the sample, the method for accelerating the weather resistance test according to claim 1 or 2.

10. The method for accelerating the weather resistance test according to claim 1 or 2, wherein the irradiation with light in the third step is performed while spraying hydrogen peroxide solution.

11. The method for accelerating the weather resistance test according to claim 1 or 2, wherein the irradiation with light in the third step is performed using a sunshine carbon arc, an ultraviolet carbon arc, a metal halide arc lamp, a xenon arc lamp, an ultraviolet fluorescent lamp, or an ultraviolet fluorescent lamp xenon lamp.

12. The method for accelerating the weather resistance test according to claim 1 or 2, wherein the cycle is repeated a plurality of times.

13. A paste used as a loading factor in the accelerated weather resistance test of a polymer material, The paste for the accelerated weathering test contains a layered clay mineral and water and exhibits acidity.

14. The paste according to claim 13, further comprising an inorganic salt.

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