Outdoor heat insulation coating and preparation method thereof

Abstract

The invention discloses an outdoor heat insulation coating as well as a preparation method and application thereof. The coating is prepared from the following components in parts by weight: 60 to 75 parts of acrylic emulsion, 10 to 20 parts of modified titanium dioxide, 5 to 10 parts of coalescing agent, 1 to 5 parts of dispersing agent, 0.1 to 0.5 part of defoaming agent, 0.1 to 0.5 part of flatting agent and 10 to 20 parts of water. The modified titanium dioxide is mixed with the acrylic emulsion, other auxiliaries and the like to obtain a heat-insulating coating, and the coating not only has the characteristics of water resistance, heat insulation and corrosion resistance, but also has high reflectivity to infrared rays in sunlight, and can reduce the absorption of a substrate to the infrared rays, reduce the surface temperature of outdoor equipment and prolong the service life of internal electronic equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of heat-insulating coatings, and in particular to a heat-insulating coating for outdoor use and a preparation method thereof. Background Art

[0002] Outdoor thermal insulation coating is a functional material primarily used to reduce heat transfer and lower the surface temperature of objects. It is widely used in construction, industrial equipment, transportation and other fields. Based on the insulation principle, thermal insulation coatings can be divided into reflective, barrier, radiant and shielding types. Reflective thermal insulation coatings use high-reflectivity materials to reflect infrared and visible light from sunlight, reducing heat accumulation on the surface of objects; barrier thermal insulation coatings use materials with low thermal conductivity to form an insulation layer, blocking heat transfer; radiant thermal insulation coatings absorb a small amount of heat and dissipate it into outer space through radiation, reducing the surface temperature of objects; shielding thermal insulation coatings form a heat shielding layer on the coating surface by emitting high electromagnetic waves, shielding infrared rays.

[0003] Thermal insulation coatings offer high thermal insulation, strong weather resistance, easy construction, and a long service life. They can significantly lower surface temperatures and reduce heat transfer, while also possessing excellent waterproof, moisture-proof, and corrosion-resistant properties, making them suitable for long-term outdoor use. Application is typically made with water-based, environmentally friendly materials that are simple to work with and easy to repair. The coating resists peeling and flaking and possesses high mechanical strength and wear resistance. In terms of application scenarios, thermal insulation coatings are widely used in the construction sector, reducing indoor temperatures and saving energy for air conditioning. They are also suitable for outdoor facilities, where they reflect sunlight to lower internal temperatures. The advantages of thermal insulation coatings lie in their energy conservation, environmental friendliness, and versatility. They reduce cooling and heating energy consumption by reducing heat transfer. Most coatings are water-based, environmentally friendly, and possess multiple functions, including waterproofing, corrosion resistance, and UV resistance.

[0004] Patent CN102993886A discloses a reflective heat-insulating exterior wall architectural coating, which belongs to the technical field of building exterior wall coatings. The coating comprises the following components by weight: an appropriate amount of water, 0.2-0.3 parts of cellulose, 0.15-0.2 parts of a pH regulator, 0.5-0.7 parts of a dispersant, 0.15-0.4 parts of a wetting agent, 1 part of a defoaming agent (0.15-0.3 parts), 18-25 parts of titanium dioxide, 8-12 parts of a filler, 2-3 parts of far-infrared ceramic powder (1250 meshes), 0-4 parts of hollow glass microspheres (65 μm), 0-8 parts of hollow glass microspheres (50 μm), 0-6 parts of hollow glass microspheres (40 μm), 20-28 parts of an acrylic copolymer elastic emulsion, 2 parts of a defoaming agent (0.15-0.3 parts), 1.0-2.5 parts of an antifreeze agent, 1.0-1.5 parts of a film-forming aid, 0.2-0.4 parts of an anticorrosive and mildew-proof agent, and 1.0-1.5 parts of a thickener. The coating is compounded with hollow glass microspheres of different sizes, which can not only ensure a smooth coating surface, high solar reflectivity, and good stain resistance, but also increase the gas volume fraction in the coating, thereby significantly improving the thermal insulation performance of the coating.

[0005] Patent CN114456659A relates to a solar heat-reflecting, heat-insulating coating and its preparation method. The coating is composed of the following components: a binder, hollow glass microspheres, a wetting and dispersing agent, a defoaming agent, an antifreeze agent, a film-forming aid, a thickener, a pH adjuster, pigments and fillers, and water. This invention significantly improves the compatibility between the silica aerogel and acrylic emulsion by treating modified xanthan gum with an alternating copolymer of 1-octadecene and maleic anhydride, and further modifying the silica aerogel using this modified xanthan gum. This enhances the coating's thermal insulation and stain resistance. The coating is suitable for use as a reflective, heat-insulating coating on building exteriors, effectively achieving energy conservation.

[0006] In reflective thermal insulation coatings, reflective fillers are key components in achieving high reflectivity. By efficiently reflecting and scattering incident light, they significantly reduce heat absorption on the coating surface, thereby achieving cooling and energy savings. Commonly used reflective fillers include titanium dioxide (TiO2), aluminum powder, and mica powder. However, these inorganic fillers have poor compatibility with the coating matrix and are prone to agglomeration, which can compromise the overall performance of the coating. Summary of the Invention

[0007] Nano-TiO2 is widely used in thermal insulation coatings due to its excellent infrared reflectivity and thermal stability. However, its high surface energy, easy agglomeration, poor dispersion, and certain photocatalytic activity may affect the long-term stability of the coating.

[0008] The present invention introduces a modified polyphenylene sulfide with a specific structure, utilizing its excellent hydrophobicity, high refractive index, and structural regularity to modify it with TiO2 under controlled conditions. The resulting composite particles exhibit improved dispersion stability, optical properties, and surface hydrophobicity. The modified polymer, grafted with an olefinic acid, is able to covalently bond with the active hydroxyl groups on the surface of the TiO2 particles. This grafting modification creates a certain steric hindrance effect between the particles in terms of physical structure, effectively reducing agglomeration and improving their uniform dispersion in the coating. Furthermore, polyphenylene sulfide itself is not UV-resistant and easily degrades. By forming a stable interface with the TiO2 particles, its environmental adaptability can be indirectly improved, helping to extend the service life of the coating.

[0009] Nano-scale TiO2 has a reflective, scattering and absorbing effect on ultraviolet rays, which can effectively block ultraviolet rays and reduce the thermal impact of ultraviolet rays on the material under the coating; at the same time, TiO2 has a high refractive index and has a good scattering effect on visible light, which can enhance the covering power and heat insulation effect of the coating. Secondly, TiO2 has a high melting point and good thermal stability. It can still maintain stable performance in high temperature environments and is suitable for a variety of heat insulation scenarios; and its thermal conductivity is low, which can effectively block heat transfer, reduce the thermal conductivity of the coating, and improve the heat insulation effect. However, the surface energy of titanium dioxide is high and it is prone to agglomeration and adhesion, resulting in poor dispersion of titanium dioxide. Therefore, it is necessary to change its surface polarity to improve dispersibility and dispersion stability.

[0010] The present invention provides a polymer that is modified. Polyphenylene sulfide, as a polymer with a relatively high refractive index, can enhance the reflective effect of titanium dioxide. Polyphenylene sulfide is composed of alternating benzene rings and sulfur atoms. The benzene rings have a relatively large conjugated system and can provide a relatively high polarizability. The sulfur atoms have a relatively large atomic weight and a relatively high molar refractive index. The polyphenylene sulfide molecular chain has relatively high regularity and crystallinity. Polymers with high crystallinity generally have a higher refractive index. However, polyphenylene sulfide is not UV-resistant. Its molecular structure will undergo significant changes under UV radiation, and the molecular chain will break. However, stably combining it with titanium dioxide can just improve this defect. The modified titanium dioxide not only has a higher refractive index and an enhanced thermal insulation effect, but the modified component also forms a certain steric hindrance on the TiO2 surface, inhibiting particle agglomeration, thereby enhancing dispersibility.

[0011] The modified titanium dioxide is mixed with acrylic emulsion and other additives to obtain a thermal insulation coating. This coating not only has waterproof, heat-insulating and corrosion-resistant properties, but also has high reflectivity for infrared rays in sunlight. It can reduce the substrate's absorption of infrared light, lower the surface temperature of outdoor equipment, and extend the service life of internal electronic equipment.

[0012] To achieve the above objectives, the present invention provides a thermal insulation coating for outdoor use, comprising the following components in parts by weight: 60 to 75 parts of acrylic emulsion, 10 to 20 parts of modified titanium dioxide, 5 to 10 parts of a film-forming aid, 1 to 5 parts of a dispersant, 0.1 to 0.5 parts of a defoaming agent, 0.1 to 0.5 parts of a leveling agent, and 10 to 20 parts of water.

[0013] The preparation method of the modified titanium dioxide comprises the following steps: X1. Add polyphenylene sulfide to N,N-dimethylformamide, then add 6-7 mol / L sodium borohydride methanol solution. Heat to 70-80°C under an inert atmosphere and stir for 10-20 hours. After the reaction is complete, cool to room temperature, dilute with methanol, filter, and dry the filter cake before use in the next step. X2. Add the product of the previous step, benzoin dimethyl ether, and olefinic acid to N,N-dimethylformamide, degas, irradiate with UV light, stir for 2-5 hours, dilute with methanol, filter, and dry the filter cake to obtain modified polyphenylene sulfide; X3. Add modified polyphenylene sulfide to N,N-dimethylformamide, then add titanium dioxide, heat to 60-70°C under an inert atmosphere and stir for 6-8 hours. After the reaction is completed, cool to room temperature, filter, wash and dry the filter cake to obtain modified titanium dioxide.

[0014] Furthermore, the mass ratio of the polyphenylene sulfide to the methanol solution of N,N-dimethylformamide and sodium borohydride is 1:30-50:4-5.

[0015] Furthermore, in step X2, the mass ratio of the product of the previous step to benzoin dimethyl ether, olefinic acid, and N,N-dimethylformamide is 1:0.01-0.02:1-3:10-20.

[0016] Furthermore, the power of the UV irradiation is 60 mW / cm 2 , under 365nm ultraviolet light radiation.

[0017] Furthermore, the mass ratio of the modified polyphenylene sulfide to N,N-dimethylformamide and titanium dioxide is 0.01-0.05:30-60:1.

[0018] Preferably, the olefinic acid is one of acrylic acid, methacrylic acid or 2-methylalkenylene decanoic acid.

[0019] Preferably, the preparation method of the modified titanium dioxide comprises the following steps: X1. Add polyphenylene sulfide to N,N-dimethylformamide, and then add a 6-7 mol / L methanol solution of sodium borohydride. The mass ratio of polyphenylene sulfide to N,N-dimethylformamide and the methanol solution of sodium borohydride is 1:30-50:4-5. Heat to 70-80°C and stir for 10-20 hours under an inert atmosphere. After the reaction is completed, cool to room temperature, add 5 times the amount of methanol to dilute, filter, and dry the filter cake before use in the next step. X2. Add the product of the previous step, benzoin dimethyl ether, and olefinic acid to N,N-dimethylformamide. The mass ratio of the product of the previous step to benzoin dimethyl ether, olefinic acid, and N,N-dimethylformamide is 1:0.01~0.02:1~3:10~20. After degassing, the power is 60mW / cm 2 , irradiate under 365nm ultraviolet radiation, stir for 2~5h, add 5 times methanol to dilute, filter, and dry the filter cake to obtain modified polyphenylene sulfide; X3. Add modified polyphenylene sulfide to N,N-dimethylformamide, and then add titanium dioxide. The mass ratio of modified polyphenylene sulfide to N,N-dimethylformamide and titanium dioxide is 0.01~0.05:30~60:1. Heat to 60~70℃ under an inert atmosphere and stir for 6~8h. After the reaction is completed, cool to room temperature, filter, wash and dry the filter cake to obtain modified titanium dioxide.

[0020] Furthermore, the film-forming aid is one of propylene glycol butyl ether, ethylene glycol butyl ether or dodecyl alcohol ester.

[0021] Furthermore, the dispersant is one of polyacrylate, phosphate or silicate.

[0022] Furthermore, the defoaming agent is one of an organosilicon defoaming agent, a polyether defoaming agent or a fatty acid defoaming agent.

[0023] Furthermore, the leveling agent is a silicone leveling agent or an acrylate leveling agent.

[0024] A method for preparing an outdoor thermal insulation coating comprises the following steps: After mixing the components according to the proportions and stirring evenly, the coating is obtained. The surface to be coated is cleaned and polished, and then the coating is applied thereon. After drying, the outdoor heat-insulating coating is obtained.

[0025] The present invention also provides an application of an outdoor heat-insulating coating in fields such as outdoor cabinets.

[0026] Beneficial effects of the present invention: The thermal insulation coating provided by the present invention has good infrared reflectivity, weather resistance and hydrophobicity. By adopting polymer-modified titanium dioxide as a functional filler, the reflection efficiency of the coating for the mid-infrared band of sunlight is improved, thereby significantly reducing the temperature rise effect of the coated surface. In a comparative test, the sunlight reflectance of the coating was increased by more than 10%, the thermal insulation temperature difference was increased by more than 7°C, and the water contact angle was significantly improved, showing excellent waterproof performance and thermal control effects. The modified functional filler shows better dispersibility and stability in the water-based acrylic emulsion system, good film uniformity, strong adhesion, and no obvious agglomeration and sedimentation, while maintaining excellent alkali resistance and corrosion resistance, and is suitable for application scenarios exposed to outdoor environments for a long time, such as surface thermal insulation protection of equipment such as communication cabinets and outdoor control boxes. DETAILED DESCRIPTION

[0027] 2-Methylidenedodecanoic acid, CAS No.: 52756-21-5.

[0028] Acrylic emulsion, model: AC8004, comes from Guangzhou Qiyuan New Materials Co., Ltd.

[0029] Polyacrylate, model: ACRMER 9300, from Dow.

[0030] Silicone defoamer, model: BYK-024, from BYK Chemical.

[0031] Acrylate leveling agent, model: BYK-358N, from BYK Chemical.

[0032] Polyphenylene sulfide, brand: A130M, comes from Toray of Japan.

[0033] Titanium dioxide, particle size: 20~50nm.

[0034] Example 1 A method for preparing an outdoor thermal insulation coating comprises the following steps, in parts by weight: Mix 70 parts of acrylic emulsion, 15 parts of modified titanium dioxide, 8 parts of lauryl alcohol ester, 2 parts of polyacrylate dispersant, 0.3 parts of silicone defoamer, 0.2 parts of acrylic leveling agent and 15 parts of water, and stir evenly to obtain a coating. After cleaning and polishing the surface to be coated, apply the coating thereon, and after drying, obtain a heat-insulating coating for outdoor use.

[0035] The preparation method of the modified titanium dioxide comprises the following steps: X1. Add polyphenylene sulfide to N,N-dimethylformamide, and then add a 6.5 mol / L methanol solution of sodium borohydride. The mass ratio of polyphenylene sulfide to N,N-dimethylformamide and the methanol solution of sodium borohydride is 1:40:4.5. Heat to 75°C and stir for 15 hours under an inert atmosphere. After the reaction is completed, cool to room temperature, add 5 times the amount of methanol to dilute, filter, and dry the filter cake before use in the next step. X2. Add the product of the previous step, benzoin dimethyl ether, and acrylic acid to N,N-dimethylformamide. The mass ratio of the product of the previous step to benzoin dimethyl ether, acrylic acid, and N,N-dimethylformamide is 1:0.01:2:15. After degassing, the power is 60mW / cm 2 , irradiated under 365nm ultraviolet radiation, stirred for 4h, diluted with 5 times methanol, filtered, and dried the filter cake to obtain modified polyphenylene sulfide; X3. Add modified polyphenylene sulfide to N,N-dimethylformamide, and then add titanium dioxide. The mass ratio of modified polyphenylene sulfide to N,N-dimethylformamide and titanium dioxide is 0.03:50:1. Heat to 65°C and stir for 7 hours under an inert atmosphere. After the reaction is completed, cool to room temperature, filter, and wash and dry the filter cake to obtain modified titanium dioxide.

[0036] Example 2 The process is basically the same as Example 1, except that acrylic acid is replaced by methacrylic acid.

[0037] Example 3 The process is basically the same as Example 1, except that acrylic acid is replaced by 2-methylalkenylenedecanoic acid.

[0038] Comparative Example 1 A method for preparing an outdoor thermal insulation coating comprises the following steps, in parts by weight: Mix 70 parts of acrylic emulsion, 15 parts of titanium dioxide, 8 parts of lauryl alcohol ester, 2 parts of polyacrylate dispersant, 0.3 parts of silicone defoamer, 0.2 parts of acrylic leveling agent and 15 parts of water, and stir evenly to obtain a coating. After cleaning and polishing the surface to be coated, apply the coating thereon, and after drying, obtain a heat-insulating coating for outdoor use.

[0039] Comparative Example 2 A method for preparing an outdoor thermal insulation coating comprises the following steps, in parts by weight: Mix 70 parts of acrylic emulsion, 15 parts of modified titanium dioxide, 8 parts of lauryl alcohol ester, 2 parts of polyacrylate dispersant, 0.3 parts of silicone defoamer, 0.2 parts of acrylic leveling agent and 15 parts of water, and stir evenly to obtain a coating. After cleaning and polishing the surface to be coated, apply the coating thereon, and after drying, obtain a heat-insulating coating for outdoor use.

[0040] The preparation method of the modified titanium dioxide comprises the following steps: Add 0.03 parts of 3-(isobutyleneoxy)propyltrimethoxysilane to 50 parts of water, add 1 mol / L dilute hydrochloric acid to adjust the pH to 3, stir for 30 minutes to hydrolyze and disperse, then mix with 1 part of titanium dioxide, stir at 70°C for 2 hours, cool to room temperature after the reaction is completed, filter, wash and dry the filter cake to obtain modified titanium dioxide.

[0041] Test Example 1 The coatings prepared in the examples and control examples were subjected to waterproof and anti-corrosion tests. The waterproof test was conducted by measuring the static water contact angle, and the anti-corrosion test was conducted according to the method in GB / T 9755-2024 "Synthetic resin emulsion wall coatings".

[0042] Table 1

[0043] Materials with a water contact angle greater than 90° are considered hydrophobic, and those greater than 150° are considered superhydrophobic.

[0044] As can be seen from Table 2, the hydrophobicity of the coating can be improved by modifying titanium dioxide. Titanium dioxide itself has a certain hydrophilicity, and its surface can adsorb water molecules. The acrylic emulsion itself contains hydrophilic groups, such as carboxyl groups, hydroxyl groups, etc. These groups can form hydrogen bonds with water molecules, thereby improving the hydrophilicity of the coating. However, when the coating has good hydrophilicity, it is not conducive to the long-term stability of the coating. In Control Example 2, titanium dioxide is grafted and modified so that titanium dioxide has hydrophobic groups, thereby giving the coating a certain hydrophobicity. In Examples 1 to 3, titanium dioxide is modified with polyphenylene sulfide, and polyphenylene sulfide itself is a hydrophobic polymer and has good waterproof and anti-corrosion properties. Therefore, compared with Control Example 2, the water contact angle of the embodiment is higher.

[0045] Compared with Examples 1 and 2, Example 3 uses an olefinic acid having a hydrophobic alkyl chain, so the hydrophobic effect is better and the water contact angle of the prepared coating is naturally higher.

[0046] Test Example 2 The coatings prepared in the Examples and Comparative Examples were tested for solar reflectance, near-infrared reflectance, hemispherical emissivity, and thermal insulation temperature difference according to the methods specified in JG / T 235-2014, "Architectural Reflective Thermal Insulation Coatings." Solar reflectance measures the material's reflectance across the solar spectrum (300-2500 nm) and calculates a weighted average, reflecting its ability to reflect sunlight. Near-infrared reflectance refers to the reflectance within the 780-2500 nm band. Hemispherical emissivity measures the material's hemispherical thermal radiation capacity, measured using a radiometer, as a ratio to blackbody radiation. Thermal insulation temperature difference simulates sunlight exposure and measures the temperature difference between the back of a coated test panel and a blank panel, reflecting its thermal insulation performance. Specific test results are shown in Table 2.

[0047] Table 2

[0048] As can be seen from Table 2, the heat reflective performance and thermal insulation performance of the coating obtained in the embodiment are significantly better than those in the control example. This may be because the poor dispersibility of titanium dioxide in the control example 1 makes it easy to agglomerate, thereby affecting the optical reflection. In the embodiment, modified polyphenylene sulfide is used to graft titanium dioxide. Polyphenylene sulfide, as a polymer with a high refractive index, can improve the reflective effect of titanium dioxide. Polyphenylene sulfide is composed of alternating benzene rings and sulfur atoms. The benzene rings have a large conjugated system and can provide a high polarizability. The sulfur atom has a large atomic weight and a high molar refractive index. The polyphenylene sulfide molecular chain has high regularity and crystallinity. Polymers with high crystallinity usually have a higher refractive index. Polyphenylene sulfide is not UV-resistant. Its molecular structure will undergo significant changes under ultraviolet radiation, and the molecular chain will break. Stably combining it with titanium dioxide can just improve this defect. The modified titanium dioxide not only has a higher refractive index and improved thermal insulation effect, but also forms a certain steric hindrance on the TiO2 surface, inhibiting particle agglomeration, thereby enhancing dispersibility. The modified titanium dioxide is mixed with acrylic emulsion and other additives to obtain a thermal insulation coating, which has high reflectivity to infrared rays in sunlight and therefore has good thermal insulation performance. It can reduce the substrate's absorption of infrared light, lower the surface temperature of outdoor equipment, and extend the service life of internal electronic equipment.

[0049] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A thermal insulation coating for outdoor use, characterized in that: The invention comprises the following components in parts by weight: 60-75 parts of acrylic emulsion, 10-20 parts of modified titanium dioxide, 5-10 parts of film-forming aid, 1-5 parts of dispersant, 0.1-0.5 parts of defoaming agent, 0.1-0.5 parts of leveling agent and 10-20 parts of water; The preparation method of the modified titanium dioxide comprises the following steps: X1. Add polyphenylene sulfide to N,N-dimethylformamide, then add 6-7 mol / L sodium borohydride methanol solution. Heat to 70-80°C under an inert atmosphere and stir for 10-20 hours. After the reaction is complete, cool to room temperature, dilute with methanol, filter, and dry the filter cake before use in the next step. X2. Add the product of the previous step, benzoin dimethyl ether, and olefinic acid to N,N-dimethylformamide, degas, irradiate with UV light, stir for 2-5 hours, dilute with methanol, filter, and dry the filter cake to obtain modified polyphenylene sulfide; X3. Add modified polyphenylene sulfide to N,N-dimethylformamide, then add titanium dioxide, heat to 60-70°C under an inert atmosphere and stir for 6-8 hours. After the reaction is completed, cool to room temperature, filter, wash and dry the filter cake to obtain modified titanium dioxide.

2. The outdoor thermal insulation coating according to claim 1, wherein the mass ratio of the polyphenylene sulfide to the methanol solution of N,N-dimethylformamide and sodium borohydride is 1:30~50:4~5.

3. The outdoor thermal insulation coating according to claim 1, wherein the mass ratio of the product of the previous step to benzoin dimethyl ether, olefinic acid, and N,N-dimethylformamide in step X2 is 1:0.01~0.02:1~3:10~20.

4. The outdoor heat-insulating coating according to claim 1, wherein the power of the UV irradiation is 60 mW / cm 2 , under 365nm ultraviolet light radiation.

5. The outdoor thermal insulation coating according to claim 1, wherein the mass ratio of the modified polyphenylene sulfide to N,N-dimethylformamide and titanium dioxide is 0.01-0.05:30-60:

1.

6. The outdoor heat-insulating coating according to claim 1, wherein the film-forming aid is one of propylene glycol butyl ether, ethylene glycol butyl ether or dodecyl alcohol ester.

7. The outdoor thermal insulation coating according to claim 1, characterized in that the dispersant is one of polyacrylate, phosphate or silicate; the defoamer is one of silicone defoamer, polyether defoamer or fatty acid defoamer; and the leveling agent is one of silicone leveling agent or acrylate leveling agent.

8. A method for preparing an outdoor thermal insulation coating according to any one of claims 1 to 7, characterized in that: The steps include: After mixing the components according to the proportions and stirring evenly, the coating is obtained. The surface to be coated is cleaned and polished, and then the coating is applied thereon. After drying, the outdoor heat-insulating coating is obtained.

9. Use of the outdoor thermal insulation coating according to any one of claims 1 to 7 in fields such as outdoor cabinets.

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