JP6883411B2 - Covering material for raising seedlings - Google Patents

Description

The present invention relates to a covering material used in a seedling raising period such as paddy rice cultivation.

For example, in paddy rice cultivation, there is a seedling raising period performed in a greenhouse and a Honda management period performed in a paddy field. The seedling raising period is a period in which the seedlings are completed through a germination period from sowing to emergence, a greening period until the seedlings reach a predetermined length, and a hardening period in which the seedlings are acclimatized to the outside air.

During the seedling raising period, mainly during the germination period and the greening period, seedlings are placed in a predetermined box and covered with a silver-colored coating material formed by blending or applying metal particles such as aluminum. (See, for example, Patent Documents 1 and 2). By covering with the covering material in this way, the heat retaining effect is exhibited, and for example, the temperature is controlled in the range of about 30 to 32 ° C. in the daytime of the budding period and about 20 to 25 ° C. in the daytime of the greening period. Although light is almost unnecessary during the emergence period, many coating materials allow a predetermined amount of light to pass through so that the seedlings can be managed by irradiating the seedlings with light such as cloudiness during the greening period.

JP-A-54-106589 Japanese Patent Application Laid-Open No. 60-251826

By the way, when the inventor visited so-called agricultural cooperatives and farmers in various places to hear and investigate problems during seedling raising, it was found that the number of seedling burns, which is a high temperature disorder of seedlings, has increased in recent years. That is, the general seedling raising period is from April to May, but there are days when the outside temperature reaches 20 to 25 ° C even in April to May due to the influence of global warming, so the temperature inside the house is about 30. It was found that the temperature may reach ~ 35 ° C., and in the coating material, the temperature may reach about 45-50 ° C. Then, in the covering material, when the temperature reaches about 40 ° C., the root growth begins to be adversely affected, and when the temperature reaches about 45 ° C., seedlings are likely to burn. For this reason, farmers take measures such as raising the hem of the house and covering materials at the right timing so that the temperature does not rise too much, but it is difficult for part-time farmers to determine when to raise the hem. Is. It was also found that it is not always easy for full-time farmers to control the temperature by such hemming.

The present invention is for solving the above problems, and is a coating for raising seedlings that can be controlled to a temperature that does not burn seedlings even when the outside air temperature is high, and that can take in the light required for raising seedlings. The purpose is to provide materials.

The above-mentioned problem is white, which is a coating material for raising seedlings that is used for heat retention during the seedling raising period and covers the container that houses the seedlings, and is a layer that is exposed to the outside of the container and contains a white pigment. By having the layer and the silver layer which is a layer in which the metal particles which are exposed inside the container and become silver are mixed, the reflectance to near infrared rays having a wavelength of 800 nm is approximately 42 to 73%. Thus, the solution is to use a coating material for raising seedlings so that the transmittance of visible light having a wavelength in the visible light region is approximately 5 to 20%.

According to the above configuration, by setting the reflectance to near infrared rays of 800 nm to about 42 to 73%, even if the outside air temperature becomes 20 to 25 ° C., the covering material can be used without turning over the hem of the house or the covering material. The covered containment can be kept within at least 45 ° C to prevent seedling burns, the containment can be kept warm within the required temperature range, and the seedlings can be exposed to the light required for the greening period. ..
That is, the reflectance for infrared rays having a wavelength of 800 nm can be used as a guide for reflecting the near infrared region that has a great influence on the temperature, and increasing this reflectance can effectively suppress the high temperature. Therefore, it is preferable to increase the reflectance of near-infrared rays, and by adjusting the reflectance of near-infrared rays at 800 nm to approximately 42%, accommodation during the greening period (depending on the location, usually April in the case of paddy rice) is accommodated. The temperature inside the body could be suppressed within about 45 ° C.
On the other hand, if the reflectance of near-infrared rays of 800 nm is increased too much, there is still a cool period during the seedling raising period, which impairs the heat retention property, which is the original purpose of the covering material, and may cause a delay in growth. Therefore, the reflectance is preferably about 73% or less. In the experiment, by setting the reflectance of near infrared rays at 800 nm to about 72.2%, the temperature inside the containment during the seedling raising period was raised to about 38 ° C even on a hot day (for example, a day when the outside temperature was 25 ° C). At the same time, the average daytime temperature could be set to about 20 ° C even on a cold day (note that when the reflectance of near infrared rays at 800 nm is about 42%, the temperature is lower than when it is about 73%. Not). In this respect, in the case of paddy rice, it is necessary to keep the daytime temperature at about 20 to 32 ° C, although it depends on the place, time, type of seedling, and farming method. From the above, it is most preferable that the reflectance of the coating material for raising seedlings at 800 nm is approximately 42% to 73%.
Then, it was found by experiments that such a numerical value can be achieved by the outer layer containing the white pigment and the inner layer containing the metal particles which are inside the outer layer and become silvery. That is, if only the silver layer called silver poly as in the conventional case is used, the heat retention is certainly excellent, but the reflectance of infrared rays having a wavelength of 800 nm can be suppressed to only about 35 to 36%. Therefore, while maintaining the heat-retaining effect with this silver layer, a white layer containing a white pigment having a high reflectance effect was provided on the silver layer. However, since the conventional white pigment has a high light-shielding property such as 90% or more, the reflectance of infrared rays having a wavelength of 800 nm can be substantially reduced by forming a white layer in which the content and thickness of the white pigment are devised. It is set to ~ 73%. The white layer may be one layer or two or more consecutive layers, and the white pigment has a predetermined content with respect to the entire white layer, and the white layer has a predetermined total. It suffices to have the thickness of.
Further, by setting the content of the white pigment in the white layer to a predetermined amount, the transmittance of visible light having a wavelength in the wavelength region of 380 nm to 750 nm (hereinafter referred to as “visible light region”) is 5 to 20% (greening period). It was also possible to maintain the known transmittance required for the above. This 5 to 20% transmittance belongs to the known transmittance that has been practiced in conventional coating materials for raising seedlings, thereby ensuring the same amount of light as conventional products, for example, during the greening period. be able to. If it is within the visible light region, the error in the light transmittance is small. Therefore, a white pigment or the like is used so that the transmittance of a part of the visible light within the visible light region is approximately 5 to 20%. The amount may be set, and preferably the transmittance of visible light at 500 nm is set to be about 5 to 20%.

Further, preferably, the white pigment is titanium oxide, the metal particles are aluminum, and the ratio of the titanium oxide to the white layer is approximately 6 to 24% by weight.
As a result, the reflectance for near infrared rays having a wavelength of 800 nm can be kept in the range of about 42 to 73%. That is, according to an experiment, when titanium oxide is blended in the white layer in an amount of about 6% by weight, the reflectance of near infrared rays having a wavelength of 800 nm can be set to about 42.6%, and titanium oxide is added in the white layer in an amount of about 24% by weight. When blended, the reflectance could be about 72.2%.
As a result of the experiment, it was found that when the metal particles are aluminum, increasing or decreasing the amount has almost no effect on the reflectance of near infrared rays having a wavelength of 800 nm. Therefore, in order to obtain the above-mentioned preferable reflectance of near infrared rays, it is only necessary to consider the blending of titanium oxide at a predetermined thickness of the white layer.
By the way, it has been found that the composition of titanium oxide in the white layer affects the transmittance of visible light having a wavelength in the visible light region, but if the proportion of the titanium oxide is set to about 6 to 24% by weight, It was also found that the transmittance of visible light having a wavelength in the visible light region can be set to 5 to 20% under a predetermined amount of aluminum. Therefore, in order to obtain the desired reflectance for near infrared rays, the composition of titanium oxide is adjusted, and the transmittance of the wavelength in the visible light region obtained as a result of the adjustment is visible by adjusting the composition of aluminum. The desired transmittance of the wavelength in the light region can be obtained.
Further, it is preferable that the ratio of aluminum to the silver layer is about 2 to 5% by weight.
As a result, it is possible to obtain a transmittance of approximately 5 to 20% as the transmittance of visible light having a wavelength in the visible light region without changing the reflectance to near infrared rays having a wavelength of 800 nm.
Further, preferably, the white layer has a first white layer which is the outermost layer, and a second white layer sandwiched between the first white layer and the silver layer. The first white layer, the second white layer, and the silver layer are continuously formed, and another layer is interposed between the first white layer, the second white layer, and the silver layer. Instead, the thickness of the first white layer, the thickness of the second white layer, and the thickness of the silver layer have the same thickness.
As a result, it is possible to suppress an excessive rise in the temperature of the inner space between the seedling raising covering material and the soil contained in the container.

As described above, according to the present invention, a coating material for raising seedlings that can be controlled to a temperature that does not burn seedlings even when the outside air temperature is high and that can take in the light required for raising seedlings. Can be provided.

It is a figure which shows the state in the house at the time of raising seedlings of paddy rice, FIG. 1A is a schematic vertical sectional view of a house, and FIG. Figure. The figure which shows the relationship between the wavelength of light and radiant energy. Temperature data in the containment from April 14th to 19th obtained by the experiment. Temperature data in the containment from May 6 to 14 obtained by the experiment. Test data on the proportion of titanium oxide and aluminum contained to obtain the desired reflectance and transmittance. Test data on the ratio of titanium oxide and aluminum when the coating material for raising seedlings has a two-layer structure of white layer and silver layer. A cross-sectional view which is a modification of the embodiment of the present invention and corresponds to FIG. 1 (B).

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Since the embodiments described below are suitable specific examples of the present invention, various technically preferable limitations are added, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, the present invention is not limited to these aspects. Further, the same reference numerals given in each figure have the same structure.

FIG. 1 is a diagram showing the inside of the house 10 during the seedling raising period of paddy rice, and FIG. 1 (A) is a schematic vertical sectional view of the house 10. As shown in FIG. 1, in paddy rice cultivation, before planting seedlings in a paddy field, seedlings are raised in a house 10 until they reach a predetermined length (for example, 12 cm). The house 10 is a known so-called vinyl house, and is formed by forming a resin film such as a substantially transparent vinyl chloride film or a special polyolefin film into a substantially dome shape. In mainland Japan, the temperature of the inner space S1 of the house 10 is, for example, a maximum temperature of about 18 to 20 ° C when the outside air temperature is about 14 ° C., and a maximum temperature of 30 to 30 when the outside air temperature is 20 to 25 ° C. It becomes 35 ° C. The house 10 is not an essential condition in the present invention, and can be used inside what is called a tunnel, for example.

Then, in the seedling raising period, an accommodating body 20 for accommodating seedlings is placed in the house 10, and the accommodating body 20 is covered with a seedling raising covering material (hereinafter, referred to as “covering material”) 30.
The housing 20 is made of resin or wood, is also called a nursery box, has a tray shape with an open upper side, and has a plurality of small holes at the bottom. Soil CR is put in the housing 20, seeds (not shown) are sown on it (clan seeds), and soil CR is thinly covered on the seeds (clan seeds). The accommodating bodies 20 in FIG. 1 are arranged in two rows, for a total of four rows, but may be in one to three rows, or in five or more rows.

The covering material 30 is a thin sheet that forms an inner space S2 with the soil CR and is placed on the housing 20 so as to seal the inner space S2.
The covering material 30 is a heat insulating material for heat-retaining the inside space S2 of the housing 20 to promote the growth of seedlings after budding and budding, and is used continuously in the budding period and the greening period. .. The appropriate temperature of the inner space S2 varies depending on the type, time, and area of raising seedlings, but in the case of paddy rice, it is generally about 30 to 32 ° C during the daytime during the emergence period (early April) and during the greening period (mid-April). It is preferable to keep the temperature at about 20 to 25 ° C during the daytime. At night, it is preferable that the temperature is about 15 ° C. or higher in both the germination period and the greening period.
The covering material 30 is also used as a shade. That is, when the seedlings are whitened when suddenly exposed to strong light when the seedlings are suddenly exposed to strong light after the germination stage, which does not require light, the seedlings become a shade for dim and cloudy light. Therefore, the coating material 30 used from the budding stage to the greening stage is required to have not only heat retention but also light transmission to the extent that dim light can be inserted. Regarding this light transmittance, as a known fact, it is preferable that the transmittance of visible light having a wavelength in the visible light region is about 5 to 20%. This is because if the transmittance is less than 5%, the growth of seedlings is likely to be hindered due to insufficient photosynthesis and heat retention, and if it exceeds 20%, the seedlings may be whitened due to sudden exposure to strong light. If the transmittance exceeds 20%, whitening of seedlings does not always occur, but it is better not to exceed 20% transmittance even considering the balance between heat retention and prevention of high temperature damage. preferable.

FIG. 1B is a vertical cross-sectional view of the covering material 30 (PA portion of FIG. 1A) according to the embodiment of the present invention.
As shown in this figure, the covering material 30 is composed of a white layer 40 which is a white layer and a silver layer 32 which is a silver layer. The white layer 40 is an outer layer exposed to the outside of the housing 20 of FIG. 1 (A) (that is, the inner space S1), and the silver layer 32 of FIG. 1 (B) is the inside of the housing 20 of FIG. 1 (A). It is an inner layer exposed to (that is, the inner space S2).

The silver layer 32 is mainly used for maintaining the temperature of the inner space S2, repels the radiant heat of the inner space S2, and effectively prevents the radiant heat from being released to the outside.
The silver layer 32 of this embodiment is based on highly transparent linear low density polyethylene (LLDPE). Since this linear low-density polyethylene has softness, it is excellent in handleability, but it is inferior in weather resistance. Therefore, a substantially transparent weathering agent (ultraviolet absorber), an antioxidant, and metallocene linear low-density polyethylene (M-LLDPE) are blended with this linear low-density polyethylene for a longer period of time (seedling raising). Although it depends on the sheet storage condition other than the period, it may exceed 10 years).
Further, the silver layer 32 is blended with silver-colored metal particles. Aluminum is preferably used for the metal particles, and the ratio of aluminum to the silver layer 32 is preferably in the range of about 2 to 5% by weight, and is 2% in the case of the present embodiment. The ratio of this aluminum may be determined based on the blending ratio of titanium oxide in the white layer 40, which will be described later.

The white layer 40 is a layer mainly used for suppressing an excessive rise in the temperature of the inner space S2, and can be whitened by blending a white pigment such as ^{titanium oxide (TiO 2).} is there.
The white layer 40 of the present embodiment is further divided into two layers, and therefore, the covering material 30 includes the first white layer 34, which is the outermost layer, the first white layer 34, and the silver layer 32. It has a three-layer structure consisting of a second white layer 36 sandwiched between the white layers 36 and the innermost silver layer 32. The first white layer 34, the second white layer 36, and the silver layer 32 are continuously formed, and no other layer (including an air layer) intervenes between them. The thickness D1 of the first white layer 34, the thickness D2 of the second white layer 36, and the thickness D3 of the silver layer 32 have the same thickness, and in the case of the figure, each is 0.015 mm. Therefore, the total thickness D4 of the first and second white layers 34 and 36 is substantially doubled with respect to the thickness D3 of the silver layer 32.

The first white layer 34 in the figure is also based on linear low density polyethylene (LLDPE), which has high transparency and excellent softness. Then, the linear low-density polyethylene is blended with a substantially transparent low-density polyethylene (Low Density Polyethylene), a weathering agent (ultraviolet absorber), and an antioxidant to extend the service life. Further, the first white layer 34 of the present embodiment contains titanium oxide for forming white color. In the case of the present embodiment, the proportion of titanium oxide in the first white layer 34 is approximately 16% by weight.
Further, the second white layer 36 in the figure is also based on linear low density polyethylene (LLDPE) having high transparency and excellent softness, and titanium oxide for forming white color is blended therein. .. In the case of the present embodiment, the proportion of titanium oxide in the second white layer 36 is approximately 32% by weight. Since the second white layer 36 is an intermediate layer and is less irradiated with light, it does not contain a weather resistant agent or an antioxidant.

As described above, the titanium oxide of the first white layer 34 is approximately 16% by weight, the titanium oxide of the second white layer 34 is approximately 32% by weight, and the aluminum of the silver layer 32 is approximately 2% by weight. The coating material 30 has a reflectance of about 72.2% for near infrared rays having a wavelength of 800 nm, and a transmittance of visible light having a wavelength within the visible light region (visible light having a wavelength of 500 nm in the case of the present embodiment). It is said to be approximately 9.5%. Therefore, it is possible to prevent absorption and transmission of most of the near-infrared range FR shown in FIG. 2, which shows the relationship between the wavelength of light and radiant energy, and suppress the excessive rise in temperature of the inner space S2 in FIG. it can. That is, since near-infrared rays have a great influence on the temperature, the reflectance can be increased to effectively suppress the high temperature such as burning seedlings, and greening while preventing the absorption and transmission of near-infrared rays in this way. You can also take in the light you need for the period.

3 and 4 show the covering material of FIG. 1 (coating material having a reflectance of about 72.2% for near infrared rays having a wavelength of 800 nm and a transmittance of visible light having a wavelength of 500 μm of about 9.5%) 30. This is experimental data showing the thermal superiority over the existing coating materials of.
The sixth graph in the figure is data using the covering material 30 in FIG. Further, the graphs Nos. 1 to 5 are data using the conventional covering material, and No. 1 uses what is called silver poly consisting of only a silver sheet. No. 2 uses a non-woven fabric called Aihokka # 40 (trademark) provided inside the No. 1 silver poly. No. 3 uses what is called a healthy seedling sheet (trademark) formed from a foam sheet. No. 4 uses a coating material with aluminum vapor deposition called Polyshine (trademark). No. 5 uses a non-woven fabric called a love sheet (trademark) provided inside the No. 1 silver poly.
First, the superiority will be described with reference to FIG. Fig. 3 shows the temperature data measured every hour in the covering material (inner space S2 in Fig. 1) at the Niigata Prefectural Agricultural Research Institute from April 14th to 19th (general greening period in Niigata Prefecture). is there. In this experiment, the seedlings were sown on April 12 and then covered with a covering material (at 11:00 am) in order to obtain the same conditions as normal seedling raising.

As shown in Fig. 3, in Nos. 1, 2 and 5, there are days when the temperature rises above 40 ° C, which may adversely affect root growth even in mid-April, and in No. 2, there is a risk of seedling burning. Since there are days when the temperature exceeds 45 ° C., it is not preferable in recent years when global warming progresses. On the other hand, in No. 4, there are days when the temperature is below 25 ° C even during the day, and it cannot be said that the original covering material for the purpose of heat retention is sufficiently fulfilled.
Nos. 3 and 6 are generally in the range of 25 ° C to 35 ° C during the daytime, and can prevent high temperatures and have excellent heat retention. However, the coating material No. 3 is made of a foaming material, and is inevitably deteriorated over time in a short period of time. That is, while the covering material is often used for 10 years, the No. 3 covering material has a problem that cracks and cracks occur in 3 years at the longest, and the seedlings are burnt when exposed to sunlight. Occurs. In addition, since the No. 3 covering material is thick, there is a problem in workability. In this regard, as described in FIG. 1 (B), the coating material of No. 6 (the present embodiment) is based on low-density polyethylene having high softness in both the white layer 40 and the silver layer 32. It has excellent handleability and can withstand long-term use.

The No. 6 coating material of the present embodiment has a reflectance of about 72.2% for near infrared rays having a wavelength of 800 nm, and has a maximum temperature of about April 14 to 19, which is often in the greening period. Although it was possible to suppress the temperature to 34 ° C., it was also found that the maximum temperature during the greening period could be suppressed to within about 45 ° C. when the reflectance of near infrared rays having a wavelength of 800 nm was set to about 42% (not shown). From this, it can be seen that at the current level of global warming, seedling burning can be prevented at least during the greening period by setting the reflectance of near infrared rays having a wavelength of 800 nm to about 42% to about 73%.
As described above, the covering material of the present embodiment can prevent seedling burning, but it can be seen from FIG. 3 that the heat retention property is also exhibited without any problem. The temperature of the daytime DY was the lowest on April 18 at the time of FIG. 3, but when the covering material of No. 6 (the present embodiment) was used, the average temperature of the daytime DY on the 18th was greening. It exceeds about 20 ° C required for the period.

FIG. 4 is temperature data measured every hour in the covering material (inner space S2 in FIG. 1) at the Niigata Prefectural Agricultural Research Institute from May 6 to 14. In this experiment as well, the seedlings were sown on May 6 and then covered with a covering material (11:00 am) in order to obtain the same conditions as normal seedling raising.
In the past, this period was the period when Niigata Prefecture entered the hardening period after the greening period, but due to the promotion of global warming in the future, it is expected that the temperature during this period will occur in April, and the location and seedlings Depending on the conditions such as type and farming method, this period may be the greening period. In this regard, for example, the outside air temperature on May 13 in FIG. 4 reached a maximum of 25 ° C, but the result was that the coating material No. 6 of the present embodiment had a temperature of less than 40 ° C, which could prevent an adverse effect on root elongation. Was the only one I could get.
On the other hand, in the coating material composed of the No. 3 foam sheet, the outside temperature exceeded 40 ° C on May 13 at 25 ° C, and on other days, it was 6 compared to the No. 3 foam sheet. The temperature of the covering material is lower. From FIG. 4 and FIG. 3 described above, it can be seen that the coating material of the present embodiment is more effective in preventing high temperature than the foamed sheet as the outside air temperature increases.
Regarding the nighttime temperature, there is not much difference in temperature regardless of which of the covering materials No. 1 to No. 6 is used.

5 and 6 show the titanium oxide blended in the white layer and the aluminum blended in the silver layer, which were carried out to simultaneously obtain both the desired near-infrared reflectance and visible light transmittance described above. It is a test result about the ratio.
FIG. 5 shows the test results when the covering material has a three-layer structure as shown in FIG. 1 (B), and FIG. 6 shows the coating material having a two-layer structure of a white layer 40 and a silver layer 32 as shown in FIG. It is a test result when. The "reflectance" of FIGS. 5 and 6 is the reflectance for near infrared rays having a wavelength of 800 nm, and the "transmittance" is the transmittance of visible light having a wavelength of 500 nm. The wavelength of 500 nm is the measurement target because when the transmittance of each wavelength in the visible light region is compared, the error is within a range of several%, which is preferable as a reference value. The thickness of each of the first white layer, the second white layer, and the silver layer in FIG. 5 is 0.015 mm, the thickness of the white layer in FIG. 6 (D4 in FIG. 7) is 0.03 mm, and the silver layer. The thickness of (D3 in FIG. 7) is 0.015 mm. Further, the “white total” in FIG. 5 indicates the proportion of titanium oxide in the entire first and second white layers in% by weight.
As mentioned above, this test was carried out by increasing the reflectance of near-infrared rays with a wavelength of 800 nm to approximately 42% to 73% at least to prevent seedling burns, and to grow seedlings without problems with visible light. It is preferable that the transmittance of visible light having a wavelength in the region is about 5 to 20%, and for this purpose, it is necessary to understand how much the mixture of titanium oxide and aluminum should be.
In these tests, each coating material was irradiated with light, and the reflectance and transmittance were measured using an ultraviolet-visible near-infrared spectrophotometer V-770ST (manufactured by JASCO Corporation).

From the test results of FIGS. 5 and 6, the following was found.
First, from tests 1 to 7 in FIG. 5, it was found that the reflectance of near infrared rays increases as the proportion of titanium oxide in the entire first and second white layers increases (grasping item 1).
Further, in Test 11 and Test 12 of FIG. 5, the ratios of titanium oxide in the first white layer and the second white layer were reversed, but in each case, the reflectance was around 57%. From this, it was also found that the ratio of titanium oxide in the outer layer and the ratio of titanium oxide in the intermediate layer are substantially irrelevant to the reflectance to near infrared rays (grasp item 2).
Further, for example, in Test 1 of FIG. 5 and Test 15 of FIG. 6, the proportion of titanium oxide in the entire white layer was 6% by weight, and the reflectance was also about 43%. Similarly, in Test 3 of FIG. 5 and Test 14 of FIG. 6, the proportion and reflectance of titanium oxide in the entire white layer were similar. From this, it was found that the reflectance does not change as much as the left as long as the white layer as a whole has the same thickness regardless of whether the white layer is one layer or multiple layers (grasping item 3).

From the above, regardless of whether the white layer is one layer, multiple layers, or the proportion of titanium oxide contained in each of the multiple layers is different, the entire white layer is covered. It was found that the reflectance to near-infrared rays changes (the higher the titanium oxide, the lower the reflectance), following the ratio of the total weight of titanium oxide to the total weight.
Further, while the proportion of titanium oxide in the entire white layer in FIG. 5 was the same 24% by weight, the proportion of aluminum in weight was changed from tests 7 to 10 in which the proportion of aluminum in the silver layer was changed. It was found that the reflectance did not change as much as the left even if the amount increased (grasping item 4).
Therefore, if the reflectance of near-infrared rays having a wavelength of 800 nm is to be approximately 42% to 73%, the proportion of titanium oxide in the entire white layer is 6% by weight (see test 1 in FIG. 5) to 24% by weight (see Test 1 in FIG. 5). It was found that the test 7 in FIG. 5) should be performed (grasp item 5).

By the way, looking at tests 6 and 7 in FIG. 5, although the ratio of aluminum in the silver layer is the same in both cases, the entire white layer is compared with test 6 in which titanium oxide accounts for 22% by weight in the entire white layer. In Test 7, where titanium oxide accounts for 24% by weight, the transmittance is reduced by 1%. Looking at Tests 1 and 6 in FIG. 5, Test 6 has a higher proportion of titanium oxide in the entire white layer, although Test 6 has a lower proportion of aluminum than Test 1. The transmittance is lower than that of Test 1. From this, it can be seen that the transmittance with respect to visible light also changes (the transmittance decreases as the amount of titanium oxide increases) according to the ratio of the total weight of titanium oxide to the entire white layer (grasp item 6).
Further, looking at Tests 1 and 7 of FIG. 5, if the titanium oxide in the white layer having an overall thickness of 0.03 mm is within the range of 6 to 24% by weight, the amount of aluminum in the silver layer is set to a predetermined amount. Therefore, it can be seen that the transmittance can be set within the range of about 5 to 20% (grasp item 7).
Further, while the ratio of titanium oxide to the entire white layer in FIG. 5 was the same 24% by weight, the weight of aluminum was changed from tests 7 to 10 in which the ratio of the weight of aluminum to the silver layer was changed. It was found that the transmittance decreases as the proportion of the above increases (although the reflectance does not change as much as the left) (the transmittance decreases by about 2% as the ratio increases by 2% by weight) (grasp item 8).
From the above, in the white layer having an overall thickness of approximately 0.03 mm, the reflectance of approximately 42% to approximately 73% is set within the range of 6 to 24% by weight of titanium oxide in the entire white layer. If a predetermined transmittance is obtained and then a silver layer containing a predetermined aluminum is arranged inside, a transmittance of approximately 5 to 20% can be obtained without changing the reflectance. it can. This transmittance of approximately 5 to 20% of visible light is conventionally considered to be the transmittance required for the greening period, and from the test results in the figure, titanium oxide occupying the entire white layer is within the range of 6 to 24% by weight. In this case, it can be assumed that this can be achieved by setting the ratio of aluminum to the silver layer to 2 to 5% by weight.

The present invention is not limited to the above-described embodiment. Each configuration of each embodiment may be combined or omitted as appropriate, and may be combined with other configurations (not shown).
For example, in the above-described embodiment, it has a three-layer structure (two layers of white layer and one layer of silver layer), but as shown in FIG. 7, it has a two-layer structure (one layer of white layer and one layer). It does not matter if it is a silver layer of. In the case of a two-layer structure as shown in FIG. 7, it is preferable that the thickness D4 of the white layer 40 is approximately twice the thickness D3 of the silver layer 32.
Further, in the above embodiment, it has been described assuming that the covering material is used continuously in the budding period and the greening period and removed (unveiled) in the curing period, but the method of using the covering material of the present invention is limited to this. However, for example, it may be used only during the budding period and unveiled during the greening period. For example, when the outside air temperature is high due to the weather and the need for heat retention is low, and the inside is dim due to the position of the house, it is not necessary to use the covering material even during the greening period, and the covering material of the present invention is used. It is not always necessary during the greening season.
Further, as a preferred mode of the coating material, it has been explained that the reflectance with respect to near infrared rays having a wavelength of 800 nm is approximately 42 to 73%, but of course, near infrared rays having wavelengths before and after that are also reflected.
Further, as described above, in the present invention, the transmittance of a part of visible light within the visible light region (380 nm to 750 nm) may be approximately 5 to 20%.
Further, the seedling raising coating material of the present embodiment can be suitably used for raising seedling management of paddy rice, but may be used, for example, for heat retention in raising seedling management of onions.

20 ... containment body, 30 ... coating material for raising seedlings, 32 ... silver layer, 34 ... first white layer, 36 ... second white layer, 40 ... white layer

Claims (4)

It is used to keep the seedlings warm during the seedling raising period, and is a seedling raising covering material that covers the container containing the seedlings.
It has a white layer that is exposed to the outside of the container and is a layer containing a white pigment, and a silver layer that is a layer that is exposed to the inside of the container and is a layer containing silver-colored metal particles. The seedlings were raised so that the reflectance for near infrared rays having a wavelength of 800 nm was approximately 42 to 73%, and the transmittance for visible light having a wavelength in the visible light region was approximately 5 to 20%. Coating material for. The white pigment is titanium oxide.
The metal particles are aluminum
The coating material for raising seedlings according to claim 1, wherein the ratio of the titanium oxide to the white layer is approximately 6 to 24% by weight. The coating material for raising seedlings according to claim 2, wherein the ratio of the aluminum to the silver layer is approximately 2 to 5% by weight. The white layer is
The outermost layer, the first white layer,
A second white layer sandwiched between the first white layer and the silver layer,
Have,
The first white layer, the second white layer, and the silver layer are continuously formed, and another layer is formed between the first white layer, the second white layer, and the silver layer. The invention according to any one of claims 1 to 3, wherein the thickness of the first white layer, the thickness of the second white layer, and the thickness of the silver layer have the same thickness without intervening. Coating material for raising seedlings.

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