KR20220110353A - Transparent film heaters for vinyl greenhouses - Google Patents

Abstract

The present invention relates to a transparent planar heating element for a greenhouse, and more specifically to the transparent planar heating element for a greenhouse which is used as a covering material surrounding a frame of a greenhouse for growing crops and prevents damage from cold damage in the winter with high transparency and thermal stability and minimizes damage from excessive humidity caused by condensation from temperature difference between inside and outside, and also prevents snow accumulation outside the greenhouse. According to the present invention, the transparent planar heating element for a greenhouse comprises: a protective layer (10) forming the lowermost surface of the transparent planar heating element; a heating layer (20) composed of a thermally conductive nanomaterial, a thermally conductive inorganic material, and a polyethylene-based binder resin, laminated and formed on an upper part of the protective layer (10), and generating heat at a constant temperature by application of electricity by an electrode layer (30); and a UV coating layer (40) laminated and formed on an upper part of the heating layer (20) to form the uppermost surface of the transparent planar heating element and protecting the heating layer (20) from an external environmental factor. Accordingly, the present invention can increase production efficiency by reducing damage to crops grown in the greenhouse.

Description

Transparent film heaters for vinyl greenhouses

The present invention relates to a transparent planar heating element for a plastic house, and more particularly, it is used as a covering material surrounding the frame of a plastic house for cultivation of crops and prevents damage from cold damage in winter with high transparency and thermal stability, and the temperature difference between inside and outside It relates to a transparent planar heating element for a plastic house that minimizes damage from over-humidity due to the occurrence of dew condensation and prevents snow accumulation outside the plastic house.

A plastic house is a facility widely used for the stimulated or suppressed cultivation of vegetables, flowers, and fruit trees. , EVA, PVC refers to a greenhouse structure manufactured to artificially control light, temperature, and humidity, which are the main growth environments of plants by enclosing the covering material formed of plastic materials such as EVA and PVC.

In general, the types of greenhouses are classified according to the shape, and they are divided into tunnel type, arch type, roof type, etc. according to the shape of the roof. is selected taking into account.

In addition, the plastic house has advantages of high airtightness, relatively good thermal insulation, and relatively high light transmittance.

However, despite these advantages, in winter, in the greenhouse growing farmhouse, the cold air outside the greenhouse and the warm, humid air inside the greenhouse cause excessive moisture damage to the crops due to condensation or invincibility (no water droplets on the surface of the covering material) Damage to crops occurs due to blocking and reduction of sunlight due to defective occurrence, which accounts for most of the damage caused by farmhouse vinyl accidents. Although oil additives are mixed, the actual effect is only 3 to 4 months, so there is a problem of increasing the generation of waste vinyl.

In addition, the occurrence of heavy snowfall and long-term cold damage is gradually increasing due to global warming and extreme weather conditions. It causes economic loss to house-growing farms.

In order to reduce the damage as described above, computer simulation studies on the mechanical structure of the reinforcement material were conducted through snow load analysis, and it was possible to provide help in terms of reinforcement of the structure of the greenhouse. are in a situation that cannot be prevented or reduced.

In addition, conventionally, a snow removal system for a greenhouse that sweeps away snow accumulated on the roof by installing a monorail and a driving roller on the roof and side of the greenhouse has been developed. It is effective to some extent on narrow roofs because have.

Accordingly, various technologies related to a covering material for a plastic house having a heating function for snow removal or snowmelting of a plastic house have been proposed.

As an example, Korean Patent No. 10-1723910 discloses a heat control system for a vinyl house that can prepare for heavy snow by connecting a plurality of heating patterns coated with conductive ink on the surface of the film and providing a heating film. , this technology includes a heating film having a heating pattern formed of conductive ink on the surface of a polymer film through printing technology, so it is possible to minimize sunlight required for crops and to heat the temperature uniformly to some extent during heat generation. There is this.

However, in general, the covering material for a vinyl house is formed of a thermoplastic resin, and most of it is commercialized and used in an uncured state, so it retains a very weak property to heat. There is a risk of being easily damaged when connecting, and moreover, it will be difficult to connect a large-area vinyl house without damage.

In particular, in recent years, due to the abnormal climate phenomenon, local heavy snow and wet snow (snow containing a lot of water, 2 to 3 times heavier than construction with little water) falls a lot, so the conventional thin It may be difficult to support the weight of the snow on the top with a large-area film connected by a heating pattern, and therefore, there is a problem that the lifespan of the plastic house may be shortened.

Republic of Korea Patent Registration No. 10-1723910 (2017.03.31.)

The present invention has been devised to solve the above problems, and an object of the present invention is to maintain a uniform heating temperature with high transparency and thermal stability by being used as a covering material surrounding the frame of a plastic house for growing crops in winter season. It is to provide a transparent planar heating element for a plastic house that prevents damage from cold damage, minimizes damage from over-humidity due to condensation caused by internal and external temperature differences, and prevents snow accumulation outside the greenhouse.

In addition, another object of the present invention is to provide a transparent planar heating element for a greenhouse capable of implementing mechanical strength and durability that can sufficiently respond to a normal snow load in order to improve the structural stability of the greenhouse.

Objects of the present invention are not limited to the objects mentioned above, and other objects not mentioned will be clearly understood by those of ordinary skill in the art from the following description.

In order to achieve the above object, according to the present invention, the protective layer 10 to form the lowermost section of the transparent planar heating element; A heating layer 20 made of a thermally conductive nanomaterial, a thermally conductive inorganic material and a polyethylene-based binder resin to be laminated on the protective layer 10, and to generate heat at a predetermined temperature when electricity is applied by the electrode layer 30; and a UV coating layer 40 that is laminated on the heating layer 20 to form an uppermost cross-section of the transparent planar heating element, and protects the heating layer 20 from external environmental factors; Transparent planar heating element for a plastic house including; can provide

At this time, the heating layer 20 is characterized in that it comprises 0.5 to 20 parts by weight of the thermally conductive nanomaterial and 0.5 to 2.0 parts by weight of the thermally conductive inorganic material with respect to 100 parts by weight of the polyethylene-based binder resin. .

In addition, the thermally conductive nanomaterial is characterized in that it is a silver nanowire having a diameter of about 5 nm to 500 nm, a length of about 0.5 μm to 2,500 μm, and an aspect ratio of about 100 to 5,000.

In addition, the thermally conductive nanomaterial is a transparent planar heating element for a plastic house, characterized in that it further comprises a straight single-walled carbon nanotube (SWNT) or a thin multi-walled carbon nanotube (MWCNT).

In addition, the thermally conductive inorganic material is characterized in that it contains at least one selected from zinc oxide nanoparticles, activated zinc oxide, transparent zinc oxide, or a combination thereof.

Here, the zinc oxide nanoparticles are characterized in that the zinc oxide nanoparticles surface-treated with a PDMS (Poly Dimethyl Siloxane) coupling agent.

On the other hand, the heating layer 20 is first subjected to an extrusion pellet process of forming a master batch by mixing and extruding the thermally conductive nanomaterial and the polyethylene-based binder resin using a two-stage extruder, followed by multi-layer blow extrusion It is characterized in that it is formed by extruding the master batch, the thermally conductive inorganic material, and the polyethylene-based binder resin through a process or a multilayer film extrusion process by increasing and supplementing the amount.

The present invention is used as a covering material surrounding the frame of a plastic house for growing crops, and maintains a uniform heating temperature with high transparency and thermal stability to prevent damage from cold damage in the winter season. By minimizing damage and preventing snow accumulation outside the greenhouse, there is an advantage in that the damage to the crops grown in the greenhouse can be reduced and the production efficiency can be increased.

In addition, the present invention can be applied to a large-area plastic house by implementing mechanical strength and durability that can sufficiently respond to a normal snow load in order to improve the structural stability of the plastic house, and through this, the cost when constructing a plastic house It is possible to promote economic benefits to farms through the reduction, and furthermore, there is an advantage in that it is possible to reduce the amount of waste vinyl generated and prevent environmental pollution.

1 is a cross-sectional view of a transparent planar heating element for a plastic house according to the present invention.
Figure 2 is a perspective view showing a portion of one end of the transparent planar heating element for a plastic house according to the present invention cut away.

Advantages and features of the present invention, and a method of achieving them, will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims.

With reference to the accompanying drawings will be described in detail for the implementation of the present invention. Irrespective of the drawings, like reference numbers refer to like elements, and "and/or" includes each and every combination of one or more of the recited items.

The terminology used herein is for the purpose of describing the embodiments, and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components in addition to the stated components.

Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used with the meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not to be interpreted ideally or excessively unless clearly defined in particular.

Hereinafter, a transparent planar heating element according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of a transparent planar heating element for a plastic house according to the present invention.

As shown in FIG. 1, the transparent planar heating element for a plastic house that can be used as a covering material for a plastic house is largely a protective layer 10, a heating layer 20, an electrode layer 30 and a UV coating layer 40 are sequentially stacked. is formed

Specifically, first, the protective layer 10 is formed at the lowermost end of the transparent planar heating element, and when the transparent planar heating element is used as a covering material for a plastic house, it forms the inner surface of the covering material.

The protective layer 10 is polyethylene (PE; Polyethylene), polyamide (PA; Poly amides), polycarbonate (PC; Polycarbonate), polyolefin (PO; Poly olefine), poly propylene (PP; Poly propylene), plastic (PVC; Polyvinyl chloride), ethylenevinyl acetate copolymer (EVA; Ethylene-vinyl acetate), metallocene polypropylene (m-PP; metallocene-Poly propylene), metallocene polyolefin (m-PO; metallocene-Poly) olefine) is formed of a binder resin made of a thermoplastic resin comprising at least one selected from the group consisting of, preferably light, flexible, high toughness, transparency, impact resistance, electrical insulation, chemical resistance, water resistance, cold resistance, It may be formed of a polyethylene-based binder resin having high utility, such as oil resistance.

In addition, the polyethylene-based binder resin is low-density polyethylene (LDPE), metallocene polyethylene (m-PE), linear low-density polyethylene (LLDPE), metallocene linear low-density polyethylene (m-LLDPE), high-density polyethylene (HDPE), metal It may include at least one selected from the group consisting of rosene high-density polyethylene (m-HDPE) and ultra-high molecular weight polyethylene (UHMW-PE).

On the other hand, the protective layer 10 may be formed by using the polyethylene-based binder resin alone, but preferably, it may be formed by mixing the polyethylene-based binder resin with functional additives such as oil oil additives and transparent flame retardants.

Next, the heating layer 20 is laminated on the protective layer 10 to generate heat at a uniform temperature over the entire area when electricity is applied to the electrode layer 30 to be described later, binder resin, thermal conductive nano It is formed by mixing a material and a thermally conductive inorganic material.

Here, the binder resin constituting the heating layer 20 reduces the sense of heterogeneity with the protective layer 10, prevents the occurrence of layer separation due to a decrease in adhesive strength, and increases the transparency and mechanical strength of the transparent planar heating element. It is preferable to apply a polyethylene (PE)-based binder resin, which is the same type of resin as the binder resin of the protective layer 10, but recently, as raw materials with improved functionality are developed, different types of thermoplastic resins are used. It can also be used by mixing.

However, by applying a polyethylene-based binder resin excellent in flexibility and flex resistance and a silver nanowire having flexibility to the heating layer 20, creases or wrinkles occur during packaging, loading, storage and transportation of the completed planar heating element, resulting in a short circuit or Heat failure can be prevented.

In addition, it is effective to select a material with high thermal conductivity and high transparency for the thermally conductive nanomaterial. It is preferable to use spherical silver nanoparticles or silver nanowires, but in the case of spherical silver nanoparticles, the particles overlap each other. A silver nanowire is most preferable because a small number of junctions may be formed and the electrical disconnection may increase while the bonding strength is weak, and thus a large amount of spherical silver nanoparticles is required compared to the silver nanowire.

In general, silver nanowires have a diameter of 27.5 nm, which is 1/3 the size of a hair, and nano-sized particles have a diameter similar to that of a polymer, so it is generally known that a molecular level heating layer can be formed.

In addition, the thermally conductive nanomaterial is single-walled carbon nanotube (SWNT) or thin multi-walled carbon nanotube (SWNT) to increase the heating effect of the heating layer 20 within a range that does not significantly affect the decrease in transparency. It may contain a small amount of carbon nanotube (Multi-walled carbon nanotube, MWCNT).

In addition, the thermally conductive inorganic material may include one or more selected from zinc oxide nanoparticles (ZnO nanoparticles, ZnO NPs), active zinc oxide, transparent zinc oxide (ZINC Carbonate) or a combination thereof of a transparent conductive oxide material. However, the thermally conductive inorganic material is preferably zinc oxide (ZnO) nanoparticles, and the zinc oxide nanoparticles are transparent conductive oxides having excellent high-temperature thermal stability characteristics. It can provide effects such as stability against overcurrent, improve thermal conductivity of the heating layer 20 and protect from surge voltage (impact current), so its application in the present invention is very important.

The heating layer 20 includes about 0.5 to 20 parts by weight of the thermally conductive nanomaterial and about 0.5 to 2.0 parts by weight of the thermally conductive inorganic material with respect to 100 parts by weight of the polyethylene-based binder resin, more preferably the With respect to 100 parts by weight of the polyethylene-based binder resin, the thermally conductive nanomaterial includes about 1.0 to 10.0 parts by weight and about 0.5 to 2.0 parts by weight of zinc oxide nanoparticles, and when the thermally conductive nanomaterial is applied in less than about 0.5 parts by weight , there may be a risk that the electrical conductivity of the heating layer 20 may be lowered. On the contrary, when the thermally conductive nanomaterial is applied in excess of 20 parts by weight, the transparency of the heating layer 20 may be lowered to 80% or less, and since a large amount of relatively long particles are applied, the occurrence of entanglement between particles is reduced. may appear, and mechanical properties may be reduced, which may be undesirable as a transparent planar heating element.

In addition, most of the particle sizes of the thermally conductive nanomaterial, that is, the silver nanowire, have a diameter of about 5 nm to 500 nm, a length of about 0.5 μm to 2,500 μm, and an aspect ratio of about 100 to 5,000. Although applicable, preferably, the silver nanowire having a diameter of about 5 nm to 300 nm, a length of about 0.5 μm to 1,000 μm, and an aspect ratio of 100 to about 2,000 should be selected, and the particles of the silver nanowire If the size is applied within the corresponding range, it is possible to form the efficient heating layer 20 even with a small concentration of content, to form an electrical bridge between particles more densely and uniformly, and to secure a sufficient electrical network By doing so, when a current flows through the heating layer 20, quality instability in which heat is concentrated in a portion of the heating layer can be solved, and hot spots or interruption of current can be prevented.

In other words, the heating layer 20 formed by utilizing the long particles of the silver nanowires can obtain the same effect while using a smaller content of silver nanowires as compared with a conventional heating layer, in particular, When forming a transparent planar heating element, the transparency of the film may not be greatly reduced, and even if a short circuit occurs in some heating wires, long silver nanowires are connected like a net, so that a multi-layer structure of several layers is not necessary, As a structure in which a plurality of contact points and detours are secured, the electrical network can be sufficiently formed, so it may be very stable.

In addition, as mentioned above, the thermally conductive nanomaterial may further include 0.1 to 0.4 parts by weight of carbon nanotubes (MWCNT) in order to increase the heating effect of the heating layer 20 .

On the other hand, looking at the process of forming the heating layer 20 in detail, using a two-stage extruder, the thermally conductive nanomaterial and the polyethylene-based binder resin are pelletized through mixing and extrusion to form a master batch. After first passing through the multi-layer blow extrusion process or the multi-layer film extrusion process, the master batch is quantitatively utilized to form the heating layer 20, but the remaining composition is increased in the multi-layer blow extrusion process or the multi-layer film extrusion process and It is possible to form the high-density and uniform heat-generating layer 20 by extruding it on top of the supplementary protective layer 10 .

At this time, in the case of using a general pulverizer in the extrusion pellet process, there is a disadvantage that the length of the silver nanowire is cut too short. By utilizing the two-stage extruder without using a process or a dispersant, silver nanowires of unnecessarily long particles can be cut within the required range.

In addition, when performing the extrusion pellet process, using the two-stage extruder, the unique melt bonding force (about 90Ns/m2 to 100Ns/ ㎡), it is effective for uniform dispersion and cutting of entangled particles of silver nanowires, and furthermore, because it does not damage the structure of silver nanowires, the unique properties and electrical properties of silver nanowires and It has the advantage that it does not change or decrease the thermal conductivity properties.

In addition, by applying the uniform dispersion and cutting action of entangled particles of silver nanowires using the two-stage extruder, a conventional large-area heating element for a plastic house (heating layer) that has no choice but to use a large amount of expensive silver nanowires Contrary to this, since high electrical and thermal conductivity properties can be secured even when a small amount is used, there may be an advantage in realizing cost reduction.

And, the thickness of the heating layer 20 extruded through the multi-layer blown extrusion process or the multi-layer film extrusion process is about 5 μm to 200 μm, preferably about 10 μm to about 100 μm, and the heating layer When the thickness of (20) is less than 5 μm, the mechanical strength of the transparent planar heating element may be weakened, so it may be difficult to withstand normal snow weight, and the thickness of the heating layer 20 is reduced to about 200 μm When the above is applied, the transparency of the transparent planar heating element is lowered, so it may be difficult to receive sufficient sunlight for the growth of crops.

In addition, in the multi-layer blow extrusion process performed to extrude the heating layer 20, the molten resin is expanded into a tube-shaped bubble through a circular extrusion die and an air ring of the extruder, and the tube-shaped bubble is formed. The heating layer 20 is formed by deforming in a sheet form, but it may be an extrusion molding process that can be continuously formed into an ultra-wide, large-area sheet shape made of a slippery surface without an intermediate connection and bonding part.

At this time, in the case of the initial sheet discharged from the extrusion die at an extrusion temperature of 140° C. to 230° C., the heating layer 20 formed by the multi-layer blown extrusion process has a thick thickness and high temperature and low viscosity properties. However, it is possible to form the heating layer 20 in the form of a high-density sheet having a large area that cannot be obtained by a printing method as in the prior art while gradually stretching thinly, and through this, mechanical properties and molding methods are similar to those of polymers. However, electrical and thermal properties may have properties close to those of metals.

In addition, when the exothermic layer 20 is discharged from the die of the extruder used in the multi-layer blown extrusion process, it is entangled with the polyethylene-based binder resin having a strong bonding force while being expanded to the outside by the force of the extrusion force and the air. The cut silver nanowire particles are strongly affected by the stretching force of the polyethylene-based binder resin, and at the same time, they are widely spun and dispersed and loosened. It is possible to form the heating layer 20 in the form of a sheet consisting of a network structure of irregularly entangled fibers.

On the other hand, although the zinc oxide nanoparticles included in the heating layer 20 have a certain degree of transparency, depending on the content of the thermally conductive nanomaterial, it may cause a decrease in the transparency of the transparent planar heating element, so that the oxidation The amount of zinc nanoparticles may be appropriately changed depending on the content of the thermally conductive nanomaterial. In addition, in order to solve this problem, the zinc oxide nanoparticles surface-treated with PDMS (Poly Dimethyl Siloxane) coupling agent (Coupling Agent) By applying the particles together with the silver nanowire, it is possible to secure 80% or more of the transparency of the transparent planar heating element, and long-term thermal stability can be greatly improved.

More specifically, in order to continuously use the polyethylene-based binder resin, which is weak to heat, for the heating layer 20, a solution of a PDMS coupling agent in a weight ratio of the main agent and the curing agent in a weight ratio of 10:1 is coated on the surface of zinc oxide nanoparticles. After treatment to remove bubbles in a vacuum chamber, heat treatment at 100° C. for about 1 hour in a dry oven and surface treatment, and then mixing and applying zinc oxide in a multi-layer blown extrusion process, the transparency of the transparent planar heating element does not drop significantly. It will be possible to sufficiently improve the long-term thermal stability of the heating layer 20 and to continuously maintain the mechanical strength, thereby improving the service life of the product.

Next, the electrode layer 30 is positioned on both ends of the heating layer 20 to receive power. Preferably, a pair of the electrode layers 30 are opposite to each other at both ends of the heating layer 20 . It is formed by being adhesively connected to the heating layer 20 in a positioned state, and a detailed description of the forming step of the electrode layer 30 will be described later.

Next, the UV coating layer 40 is formed on the uppermost end of the transparent planar heating element, and when the transparent planar heating element is used as a covering material for a plastic house, it forms the outer surface of the covering material.

The UV coating layer 40 seals the outer surface of the heating layer 20 together with the protective layer 10 to prevent the heating layer 20 from coming into contact with external air and water. ) to protect

The UV coating layer 40 is composed of a polyethylene-based binder resin like the protective layer 10, and the UV coating layer 40 may also be formed using the polyethylene-based binder resin alone, but preferably the It may be configured by mixing a functional additive such as a UV blocker or a UV absorber with the polyethylene binder resin, and more preferably, the UV coating layer 40 is a UV blocker or UV absorber 5 to 100 parts by weight of the polyethylene binder resin. It may be formed by mixing 15 parts by weight.

This is to prevent the transparent planar heating element from being damaged thereby because the polyethylene-based binder resin constituting the UV coating layer 40 is weak to ultraviolet rays (UV). Since it affects the coloring of flowers or fruits, the occurrence of pests, etc. and acts as an inhibitor of plant growth, the UV blocker or the UV absorber is used in combination to form the UV coating layer 40, thereby effectively improving the productivity of greenhouse cultivation. can do it

2 is a perspective view showing a portion of one end of the transparent planar heating element for a plastic house according to the present invention cut away.

As shown in FIG. 2, on the other hand, the protective layer 10, the heating layer 20 and the UV coating layer 40 are adhered through a stretching process in a sequentially stacked state to form the transparent planar heating element, , as it passes through the middle between the nip rolls, the bonding force between the silver nanowire particles overlapping each other inside the heating layer 20 may be increased by receiving a stronger compressive force once more.

Thereafter, the transparent planar heating element can be continuously passed through a plurality of guide rolls to be wound on a winder roll, and the transparent planar heating element in the form of a roll (ROLL) wound in this way is aged at room temperature in the aging room for about 2 days or more. At this time, the aging step of the roll (ROLL) type film may be to provide an effect of continuously receiving a high pressure, similar to receiving the compression force of a compression press.

In general, when silver nanowires are applied to exothermic technology, silver nanowire particles

The strength of mutual bonding is very important and has a great influence on the quality. Usually, as a method of increasing bonding strength between silver nanowire particles, methods such as electron beam irradiation, annealing, and mechanical press are developed

In the present invention, due to the heating and softening of the silver nanowire in the blown extrusion process, the stretching process, the compression process in the nip roll, the roll-type aging process, etc., The overlapped and contacted silver nanowires are subjected to a strong compressive force for a long time, so that a uniform and high bonding force can be formed. In addition, the compositions mixed in the transparent planar heating element can be sufficiently stable from the various stresses received above. There will be.

In the above process, since the density of the heating layer 20 can be formed to be high, it will be possible to provide a uniform heating temperature to the large-area vinyl house to be achieved in the present invention.

In this case, the sheet resistance of the heating layer 20 is 100 Ohm/sq. to 1,000 Ohm/sq., preferably 200 Ohm/sq. to 700 Ohm/sq. In addition, the heating temperature of the heating layer 20 can be used in the range of 40 ℃ to 60 ℃, preferably according to the amount of snow accumulated in the plastic house formed with the transparent planar heating element temperature controller (not shown) should be managed so as not to exceed the maximum of 70 ° C. This is because the heat deformation temperature of the polyethylene-based binder resin constituting the heating layer 20 is usually as low as 80 ° C to 85 ° C.

On the other hand, the electrode layer 30 is formed of a thin copper plate, and is adhesively bonded to the end of the heating layer 20, and is specifically formed through the following process.

First, after mass-producing the transparent planar heating element formed by laminating only the protective layer 10, the heating layer 20, and the UV coating layer 40, cut to the required size, and a skiving machine capable of fine processing (or by using a leather avoider) to remove by skiving the width direction one end of the cut transparent planar heating element by the width (about 15 mm to 20 mm) where the electrode layer 30 will be formed.

In this case, the skiving machine may be replaced with a device formed by combining a sewing machine for transferring fabric and a precise buffing machine.

Next, after applying the transparent conductive adhesive 31 to the top surface of the heating layer 20 exposed to the outside through the skiving step, the transparent conductive adhesive 31 is applied to the upper surface of the external power connection part. After placing the thin copper plate to which the electrode wire 32 is connected, and drying the transparent conductive adhesive 31, the transparent planar heating element is passed through a movable compression roller or compression press to increase adhesion.

In this case, the copper thin plate constituting the electrode layer 30 may include silver (Ag) other than copper (Cu).

In addition, the transparent conductive adhesive 31 may be a commercially available conductive adhesive, and by adhering the heating layer 20 including the silver nanowire and the copper thin plate with conductivity, the mutual current can be smoothly communicated. Thus, it is possible to reduce and eliminate the contact resistance that may occur in the gap.

Thereafter, when the transparent conductive adhesive 31 is sufficiently cured and adhesion is completed, the upper surface and the side surface of the copper thin plate are sealed by using a polyethylene-based binder resin.

Preferably, a polyethylene tape is cut to a size corresponding to the width (about 15 mm to 20 mm) of the skived area after the polyethylene-based binder resin is coated on a single side to a suitable thickness on a release paper and wound to form a long roll. It is possible to seal the portion exposed to the outside by wrapping the upper surface of the copper foil adhesively connected to the heating layer 20 using In the state placed on the upper surface of the thin plate, the upper surface and the side of the copper thin plate are simultaneously heated and compressed by placing them in a heating compression press consisting of an upper mold formed in a “L” shape with a width of about 30 mm and a lower mold formed in a straight line. It can be sealed and blocked from the outside.

At this time, since the width of the skiving part is formed to be larger than the thickness of the transparent planar heating element, it is preferable that the width direction length of the upper mold is long and the height in the vertical direction is short, and the surfaces of the upper mold and the lower mold are By treating it with Teflon coating, it is possible to minimize the occurrence of product contamination even with multiple compression processes.

In addition, in the step of heating and compressing the polyethylene tape, an obstacle may occur due to a short circuit of the electrode wire exposed to the outside, but by cutting a part of the side of the upper mold, the inconvenience can be eliminated without hindering the process.

After the heat compression step of the polyethylene tape, in addition to the electrode layer 30 formation position, the place where the cross section of the heating layer 20 is unnecessarily exposed to the outside in the cutting step of the transparent planar heating element is hot melt bonding equipment or hot It is sealed with polyethylene binder resin or ethylene vinyl acetate resin (EVA: EthyleneVinyl Acetate) using a melt glue gun (HOT MELT GLUE GUN).

In addition, by connecting the end of the electrode wire 32 to a temperature controller, power supply and heating temperature can be adjusted. At this time, when an AC voltage of 220 volts is connected to the electrode layer 30, the heating layer 20 is Current flows and heat is generated, and the range of the heating temperature of the heating layer 20 may be about 30° C. to about 100° C., but the commercial heating temperature may be about 40° C. to about 60° C., and the maximum temperature is about 70 It is desirable to manage it so that it cannot exceed ℃.

On the other hand, the method of applying the transparent planar heating element to the plastic house can be used in the same way as in a general plastic house, without connecting the power source in normal times or in spring, summer, and autumn, and by supplying power and heating when necessary in winter, It is possible to remove the snow that accumulates in the plastic house in winter as quickly as possible, and also, when the temperature outside the plastic house drops and water drops are generated in the plastic house, or when there is a long-term cold damage, damage to the crops being grown is concerned. In the occurrence of various situations such as, by being able to appropriately adjust the strength and weakness of the heating temperature of the transparent planar heating element, it will be possible to reduce the damage to the crops cultivated in the greenhouse.

Hereinafter, the present invention will be described in more detail by Examples, Comparative Examples and Experimental Examples of the transparent planar heating element for a plastic house according to the present invention.

Example

With respect to 90 parts by weight of a mixture of LDPE and EVA in a 1:1 ratio, 10 parts by weight of a thermally conductive nanomaterial containing trace carbon nanotubes (CNT) is mixed with silver nanowires, and the screw L/D is 20 to 48 After preparing the extruded pellets in a two-stage extruder having a screw speed of 300 to 400/min, the remaining compositions were added according to the composition ratio shown in Table 1, and Examples 1 to 3 were prepared using a blown extruder of an 1800 mm extruder. did.

comparative example

100 parts by weight of a mixture of LDPE and EVA in a 1:1 ratio was prepared in a two-stage extruder having a screw L/D of 20 to 48 and a screw speed of 300 to 400/min. Comparative Example 1 was prepared using a blown extruder of an 1800 mm extruder by adding the remaining composition accordingly.

division material name protective layer heating layer UV coating layer Comparative Example 1 EVA 50 50 50 LDPE 45 45 45 UV blocker 5 5 5 Example 1 EVA 47 45 47 LDPE 47 46 47 UV blocker 5 5 5 Thermally Conductive Nanomaterials 0 3 0 ZnO nanoparticles (10nm ∼ 20nm) One One One Example 2 LDPE 35 32 35 EVA 30 30 30 m-LLDPE 30 30 30 UV blocker 5 5 5 Thermally Conductive Nanomaterials 0 3 0 ZnO nanoparticles (10nm to 20nm) 0 0 0 Example 3 LDPE 34 30 34 EVA 30 30 30 m-LLDPE 30 30 30 UV blocker 5 5 5 Thermally Conductive Nanomaterials 0 4 0 ZnO nanoparticles (10nm-20nm, PDMS surface treatment) One One One

Experimental Example 1

Examples 1 to 3 and Comparative Example 1 were evaluated for physical properties as shown in Table 2, where the evaluated physical properties are the best values among the test results of each of 5 specimens of Examples 1 to 3 and Comparative Example 1 and the mean value excluding the lowest value, and the test method for this is as follows.

⑴ Tensile strength test

Tensile strength was measured with a test piece of KS M3006 standard under the condition of a load cell of 50 kgf using Instron's UTM (Instron 4400 series).

(2) Flexural test

The flexural modulus was measured using a test piece of KS M3008 standard with a span distance of 50 mm and a crosshead speed of 2.5 m/min in Instron's UTM (Instron 4400 series).

⑶ UV (ultraviolet rays) blocking effect

Measuring equipment: UV Rejection (ultraviolet light transmittance meter)

⑷ Transparency measurement

Measuring equipment: Opacity Meter TOM11, SOLAR TRANSMISSION

⑸ Thermal stability

By supplying an AC voltage of 220V to each test piece, a long-term heating test was performed at 100° C., the test heating temperature being higher than the commercial maximum temperature (Comparative Example 1 was excluded from the test).

⑹ Surface temperature measurement

Measuring equipment: surface temperature measuring instrument (IR CAMERA)

According to the present invention, in 4 places of 5 m × 5 m of the test films of Examples 1, 2, and 3 according to the present invention, the temperature was measured after 10 minutes from the start of the heat generation at 60 ° C. (Comparative Example 1 is a test excluded).

division Comparative Example 1 Example 1 Example 2 Example 3 Tensile strength (kgf/㎠) 282 284 309 318 Flexural modulus (kgf/㎠) 12,571 11,996 13,125 13,350 transparency Transmittance (%) 87 76 85 84 Opacity 0.582 0.640 0.596 0.618 UV protection effect
(wavelength 350nm) 2.1 2.4 2.3 2.3 thermal stability
(Measurement of long-term heating time at 100℃) _ over 900 minutes 350 minutes
(Damage around 420 minutes) over 900 minutes Surface temperature measurement (℃)
(4 places of 5m*5m) - 61.2 60.5
60.9 60.7 60.1 61.8
61.4 60.6 61.9 60.4
60.8 61.1

As a result of measuring the surface temperature of Examples 1 to 3 and Comparative Example 1, the temperature deviation at each location was measured within 60°C ± 2.0°C, and in the case of Example 2, about 350 minutes passed at the test exothermic temperature of 100°C When the resistance started to rise slowly, it broke at about 420 minutes.

In addition, in the case of Example 1 using zinc oxide nanoparticles that were not surface-treated using PDMS and Example 3 using zinc oxide nanoparticles surface-treated using PDMS, when continuously operated at a test exothermic temperature of 100° C. , all had excellent heat-generating properties without resistance change until about 900 minutes, but in the case of Example 1, the transparency was greatly reduced, and in the case of Example 3, it was found that the transparency was reduced little.

In addition, the tensile strength test results of Examples 1 to 3 and Comparative Example 1 were found to be similar, and when specifically compared, Examples 2 and 3 had higher tensile strength than Comparative Examples 1 and 1 The appearance can be seen as a result of using an increased amount of metallocene linear low-density polyethylene (m-LLDPE) in the type of resin.

However, it is evaluated that it does not affect the increase or decrease of tensile strength in relation to the use of thermally conductive nanomaterials and zinc oxide nanoparticles (10 nm to 20 nm), but since it can greatly improve the thermal stability of the transparent planar heating element, agricultural vinyl Considering the fact that the tensile strength quality standard of House's polyethylene-based wide (multi-layer, triple) film is stipulated as 21.6N/mm2 or more/0.08mm to 0.1mm (220.32kgf/cm2 or more/0.08mm to 0.1mm). The heating film will be able to maintain sufficient mechanical strength to withstand the weight of normal snow during the heating process of the heating layer.

In addition, the results of the flexural modulus showed a predetermined difference depending on the resin used, but the flexural modulus of Examples 1 to 3 and Comparative Example 1 did not show a particularly significant difference.

On the other hand, the measurement result of the transparency showed high transparency in Comparative Example 1, but it was confirmed that the light transmittance and the opacity were significantly reduced at the same time as in Example 1, in which zinc oxide nanoparticles were applied to improve the thermal stability of the silver nanowire. In order to solve this problem, it was confirmed that in Example 3, in which zinc oxide nanoparticles surface-treated with PDMS were applied, the transparency did not significantly decrease.

Experimental Example 2

In Example 3, a specimen having a size of 34 cm × 64 cm was prepared and placed on a flat plywood, and the results of measuring the temporal performance at a heating temperature of 60° C. are shown in Table 3.

At this time, the plywood was set to a slope condition of 20 degrees, which was determined and set under the same conditions in consideration of the inclination angle of a general greenhouse roof of 20 to 30 degrees. It is judged that the snow can be sufficiently removed from the amount of snow on the plastic house with a thickness of about 10 cm.

division Contents Main Category subdivision Common Situations and Conditions outside temperature
(℃) ○ Where it snowed,
○ -3℃ ~ 0℃ power 220V AC voltage Commercial Highest Temperature
(℃) 61.5 snow cover method frame for snow
(Unit: cm) ○ Width:60, Length:30, Height:10,
○ 1.5T transparent acrylic plate connected to the upper and lower open rectangles fever film ○ Thickness: 150㎛
○ Width: 64cm, Length: 34cm Way ○ On the top of the 5T plywood, according to Example 3, place the heating film on the floor, and place the frame for the snow on the top.
→ Transfer the snow that fell around it with a shovel.
→ Remove the excess snow by scraping the top with a 30cm ruler without applying pressure.
→ Remove the frame for snow, taking care not to damage the snow. Required time to reach 60℃ from outside temperature (0℃) no snow 8 seconds 10cm snow condition 15 seconds inclination horizontality 60℃ 600 seconds passed About 3 to 4 cm high of snow remained.
(starting with switch operation) flat 20 degree slope long slope 60℃ * About 318 seconds All melted down at the bottom (including the switch operation) unidirectional slope 60℃* About 233 seconds The bottom melts and all flows down (including the switch operation) ○ Over 65℃, the heating temperature is not exceeded.

Summarizing again based on the measurement result of the physical properties of Example 3 and the measurement result of the thermal performance on snow cover, the transparent planar heating element according to the present invention does not significantly reduce the transparency, and long-term thermal stability can be maintained as it is, and the tensile strength By improving it, it is possible to maintain the mechanical strength and uniform heating temperature that can sufficiently cope with the normal snow load, so that more improved snow removal can be expected, and damage to farms due to snow can be reduced.

Although embodiments of the present invention have been described with reference to the above and the accompanying drawings, those of ordinary skill in the art to which the present invention pertains can practice the present invention in other specific forms without changing its technical spirit or essential features. You will understand that there is Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

10: protective layer
20: heating layer
30: electrode layer
31: conductive adhesive
32: electrode wire
40: UV coating layer

Claims (7)

a protective layer 10 forming the lowermost section of the transparent planar heating element;
A heating layer 20 made of a thermally conductive nanomaterial, a thermally conductive inorganic material and a polyethylene-based binder resin to be laminated on the protective layer 10, and to generate heat at a predetermined temperature when electricity is applied by the electrode layer 30; and
A transparent planar heating element for a plastic house comprising; a UV coating layer 40 that is laminated on the heating layer 20 to form the uppermost cross-section of the transparent planar heating element, and protects the heating layer 20 from external environmental factors. The method of claim 1,
The heating layer 20,
With respect to 100 parts by weight of the polyethylene-based binder resin, the transparent planar heating element for a plastic house, characterized in that it comprises 0.5 to 20 parts by weight of the thermally conductive nanomaterial and 0.5 to 2.0 parts by weight of the thermally conductive inorganic material. 3. The method of claim 2,
The thermally conductive nanomaterial,
A transparent planar heating element for a plastic house, characterized in that it is a silver nanowire having a diameter of about 5 nm to 500 nm, a length of about 0.5 μm to 2,500 μm, and an aspect ratio of about 100 to 5,000. 4. The method of claim 3,
The thermally conductive nanomaterial,
A transparent planar heating element for a vinyl house, characterized in that it further comprises a direct single-walled carbon nanotube (SWNT) or a thin multi-walled carbon nanotube (MWCNT). 3. The method of claim 2,
The thermally conductive inorganic material is
A transparent planar heating element for a plastic house, characterized in that it comprises at least one selected from zinc oxide nanoparticles, activated zinc, transparent zinc, or a combination thereof. 6. The method of claim 5,
The zinc oxide nanoparticles,
A transparent planar heating element for a vinyl house, characterized in that it is zinc oxide nanoparticles surface-treated with a PDMS (Poly Dimethyl Siloxane) coupling agent. According to claim 1,
The heating layer 20,
After first undergoing an extrusion pellet process of forming a master batch by mixing and extruding the thermally conductive nanomaterial and the polyethylene-based binder resin using a two-stage extruder, the master through a multi-layer blow extrusion process or a multi-layer film extrusion process A transparent planar heating element for a plastic house, characterized in that it is formed by extruding the batch and the thermally conductive inorganic material and the polyethylene-based binder resin by increasing and supplementing it.

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