JP2020138397A - Sheet - Google Patents

Abstract

To provide a sheet including a glass fiber cloth and a fluororesin that is capable of improving the transparency while reducing a total calorific value when the thickness of the sheet is increased.SOLUTION: A sheet includes at least one glass fiber cloth, a first resin layer including resin other than a fluororesin, which is impregnated in the glass fiber cloth, a second resin layer including resin other than a fluororesin, which is included without being impregnated in the glass fiber cloth, and a third resin layer including a fluororesin. A total concentration of bromine and silicon in the second resin layer is 30 mass% or more. The third resin layer is included in at least one surface of the sheet. The sheet has a total light transmittance of 80% or more and a haze of 20% or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sheet containing a glass fiber cloth and a fluororesin.

Conventionally, as a sheet used for a membrane material, for example, a roofing material for a building, a tent warehouse material, or the like, a sheet containing a glass fiber cloth and a resin is known. Among them, the sheet containing the glass fiber cloth and the fluororesin is known to be excellent in antifouling property, flexibility and the like. When the sheet is used as a roofing material for a building, a tent warehouse material, or the like, it may be required to be able to illuminate from the outside to the inside, and excellent translucency is also required.

As a sheet containing a glass fiber cloth and a fluororesin, a layer of a fiber-reinforced resin sheet composed of a matrix containing a resin having no fluorocarbon atom and a glass fiber cloth having an opening ratio of 20% or less embedded in the matrix. , And a laminated sheet having a fluororesin layer containing an ultraviolet absorber provided on at least one surface of the fiber-reinforced resin sheet layer (see, for example, Patent Document 1). According to the sheet, it has flame resistance, transparency, and excellent weather resistance.

Japanese Patent No. 6330810

By the way, when a membrane material is used as a building material for buildings such as commercial facilities and public facilities that are often used by many people, it may be required to be nonflammable as stipulated by the Building Standards Act and the Building Standards Act Enforcement Ordinance. is there. Further, the film material may be required to have an increased thickness from the viewpoint of handleability and the like.

Examples of the nonflammability include a total calorific value of 8 MJ / m ² or less in a heat generation test in which the surface of the sheet is irradiated with radiant heat of 50 kW / m ² from a radiant electric heater.

The sheet specifically disclosed as an example in Patent Document 1 has a thickness of 186 μm even if it has the largest thickness, and cannot be said to be excellent in handleability and the like.

On the other hand, as a result of examination by the present inventors, the amount of the fluororesin constituting the fluororesin or the fluorine atom is present for the purpose of increasing the thickness of the sheet specifically disclosed as an example of Patent Document 1. It has been found that if the amount of the matrix containing the non-resin resin is increased, it becomes difficult to reduce the total calorific value to 8 MJ / m ² or less. Further, as a result of examination by the present inventors, it has been found that if the mass of the glass fiber cloth is increased for the purpose of increasing the thickness of the sheet, the transparency of the sheet may be lowered. ..

Therefore, the present invention solves the above-mentioned problems, and in a sheet containing a glass fiber cloth and a fluororesin, when the thickness of the sheet is increased, the transparency is improved and the total calorific value is reduced. The challenge is to provide a sheet that makes it possible to achieve a better balance with.

As a result of studies by the present inventors in order to solve the above problems, it has been found that it is effective to include bromine or silicon in the resin constituting the sheet in order to reduce the total calorific value. did.

However, it is difficult for the present inventors to improve the transparency when a high concentration of bromine is contained in the matrix containing the resin having no fluorine atom in the sheet disclosed in Patent Document 1. I learned that there are cases. That is, in a resin containing bromine, such as a resin containing a bromine element as a substituent, the halogen element is a high refractive index substituent, and the refractive index of the resin may exceed 1.6, for example. Then, the present inventors, for example, when the glass fiber is a general-purpose E glass or the like, the refractive index of the resin is considerably higher than the refractive index of the glass fiber cloth when the concentration of bromine in the resin is increased. I learned that it can be expensive and it is difficult to improve the transparency of the sheet.

Further, the present inventors have found it difficult to improve the transparency of the sheet disclosed in Patent Document 1 when a silicone resin is used as a matrix containing a resin having no fluorine atom and a high concentration of silicon is contained. I learned that it may happen. That is, the present inventors have a low refractive index of about 1.4 for silicone resin and the like. For example, when the glass fiber is general-purpose E glass or the like, the refractive index of the silicone resin is that of the glass fiber cloth. It has been found that it becomes considerably lower than the refractive index, and it becomes difficult to improve the transparency of the sheet.

On the other hand, in order to improve the transparency, the present inventor has a low concentration of bromine or silicon in the matrix containing a resin having no fluorine atom in the sheet disclosed in Patent Document 1 so as not to impair the transparency. When it is contained as, the obtained sheet tends to have a high total calorific value, the amount of resin is limited, and it becomes difficult to reduce the total calorific value while increasing the thickness of the sheet. I got it. That is, in a sheet containing a glass fiber cloth and a fluororesin, when the thickness of the sheet is increased, it is a trade-off relationship between improving the transparency and reducing the total calorific value.

Then, the present inventors have further studied, and the glass fiber cloth, the first resin layer contained in the glass fiber cloth in a state of being impregnated and containing a resin other than the fluororesin, and the glass fiber cloth. A sheet containing a second resin layer containing a resin other than fluororesin and a third resin layer containing fluororesin as a surface layer, which is contained in a non-impregnated state, and is contained in a state where the glass fiber cloth is not impregnated. It is known that if the total concentration of bromine and silicon is increased in the two resin layers, it is not necessary to dilute the total concentration of bromine and silicon, and the low heat generation characteristics of the resin containing bromine or silicon can be further utilized. did. That is, by using a resin having a low total concentration of bromine and silicon (including a resin containing no bromine and silicon as described later) for the first resin layer contained in the glass fiber cloth in a state of being impregnated, the glass fiber cloth is used. A second resin layer that can be easily reduced in difference in refractive index from and is contained in the glass fiber cloth without being impregnated, separately from the first resin layer that is contained in the glass fiber cloth. By laminating and using a resin having a high concentration of bromine and silicon as the second resin layer, it is possible to fully utilize the low heat generation characteristics of the resin having a high concentration of bromine or silicon, and it is transparent when the resin weight is increased. It was found that it is possible to more preferably achieve both the improvement of the above and the reduction of the total calorific value. The present invention is an invention completed by further studying based on these findings.

That is, the present invention provides the inventions of the following aspects.
Item 1. A resin other than the fluororesin, which is contained in at least one glass fiber cloth in a state of being impregnated in the glass fiber cloth and is contained in a first resin layer containing a resin other than the fluororesin and in a state of not being impregnated in the glass fiber cloth. A sheet containing a second resin layer containing a fluororesin and a third resin layer containing a fluororesin, wherein the total concentration of bromine and silicon in the second resin layer is 30% by mass or more, and the third resin layer. Is contained on at least one surface of the sheet, and the total light transmittance is 80% or more and the haze is 20% or less.
Item 2. Item 2. The sheet according to Item 1, which has a thickness of 400 μm or more.
Item 3. Item 2. The sheet according to Item 1 or 2, wherein the glass fibers constituting the glass fiber cloth have a refractive index of 1.53 to 1.58.
Item 4. Item ^2. The sheet according to any one of Items 1 to 3, wherein the total mass of the glass fiber cloth in the sheet is 150 to 250 g / m ² .

According to the sheet of the present invention, at least one glass fiber cloth, a first resin layer contained in the glass fiber cloth in a state of being impregnated and containing a resin other than fluororesin, and a state in which the glass fiber cloth is not impregnated. A sheet containing a second resin layer containing a resin other than a fluororesin and a third resin layer containing a fluororesin, wherein the total concentration of bromine and silicon in the second resin layer is 30% by mass or more. The third resin layer is contained on at least one surface of the sheet, and the total light transmittance is 80% or more and the haze is 20% or less. Therefore, in the sheet containing the glass fiber cloth and the fluororesin, When the thickness of the sheet is increased, it is possible to further improve the transparency and reduce the total calorific value.

It is a cross-sectional schematic diagram explaining one aspect of the sheet of this invention. It is a cross-sectional schematic diagram explaining one aspect of the sheet of this invention. It is a cross-sectional schematic diagram explaining one aspect of the sheet of this invention. 4.10.2 The test equipment used when performing the heat generation test / evaluation method in the "Fireproof Performance Test / Evaluation Business Method Manual" (revised on March 1, 2014) of the Building Materials Testing Center. It is a figure which shows the outline. 4.10.2 For the test equipment used when performing the heat generation test / evaluation method in the "Fireproof Performance Test / Evaluation Business Method Manual" (revised on March 1, 2014) of the Building Materials Testing Center. It is the schematic of the included test holder and holding frame. The unit of the numerical value (dimension) shown in FIG. 5 is mm.

The sheet of the present invention is contained in a state of being impregnated with at least one glass fiber cloth and the glass fiber cloth, and is contained with a first resin layer containing a resin other than fluororesin and a state of not being impregnated with the glass fiber cloth. A sheet containing a second resin layer containing a resin other than the fluororesin and a third resin layer containing a fluororesin, wherein the total concentration of bromine and silicon in the second resin layer is 30% by mass or more. The third resin layer is contained on at least one surface of the sheet, and the total light transmittance is 80% or more and the haze is 20% or less.

For example, as shown in FIGS. 1 to 3, the sheet 1 of the present invention includes the glass fiber cloth 2 and the first resin layer 3 which is impregnated with the glass fiber cloth 2 and contains a resin other than the fluororesin. The glass fiber cloth 2 contains a second resin layer 4 containing a resin other than the fluororesin and a third resin layer 5 containing the fluororesin, and the bromine and silicon in the second resin layer 4 are contained. The total concentration is 30% by mass or more, and the third resin layer 5 is contained on at least one surface of the sheet 1.

In the sheet 1 of the present invention, at least one glass fiber cloth 2 may be contained, and a plurality of glass fiber cloths 2 may be contained. Further, as shown in FIGS. 1 to 3, in the sheet 1 of the present invention, the first resin layer 3 fills the gaps between the glass fibers constituting the glass fiber cloth 2, and the first resin layer 3 One surface side portion and the other surface side portion communicate with each other through the gap. As shown in FIGS. 1 and 3, the sheet 1 of the present invention can include a plurality of first resin layers 3 contained in a state of being impregnated in the glass fiber cloth 2. Further, although not shown in FIGS. 1 to 3, a plurality of glass fiber cloths 2 may be included in the first resin layer 3 of one layer.

In the sheet 1 of the present invention, the second resin layer 4 contained in the glass fiber cloth in a state of not being impregnated may be one layer as shown in FIG. 1, for example, or as shown in FIGS. 2 and 3. , May be multiple layers. When the second resin layer 4 is a plurality of layers, it is preferably 2 to 5 layers, and more preferably 2 to 3 layers.

For example, the sheet 1 shown in FIGS. 1 and 3 has a laminated structure in which the first resin layer 3 is laminated on both side surfaces of the second resin layer 4. Further, the sheet 1 shown in FIGS. 2 and 3 has a laminated structure in which the second resin layer 4 is laminated on both side surfaces of the first resin layer 3. In the sheet 1 of the present invention, as a specific example of the laminated structure of the first resin layer 3 and the second resin layer 4, the first resin layer 3 / the second resin layer 4 / the first resin layer 3 as shown in FIG. A laminated structure in which the second resin layer 4 / the first resin layer 3 / the second resin layer 4 are laminated in this order as shown in FIG. 2; a second resin as shown in FIG. A laminated structure in which the layer 4 / first resin layer 3 / second resin layer 4 / first resin layer 3 / second resin layer 4 are laminated in this order can be mentioned.

In the sheet 1 of the present invention, the third resin layer 5 is preferably contained on at least one surface of the sheet 1 and is preferably contained on both surfaces of the sheet 1. In the sheet 1 of the present invention, as a specific example of the laminated structure of the first resin layer 3, the second resin layer 4, and the third resin layer 5, the third resin layer 5 / first resin layer 3 as shown in FIG. / 2nd resin layer 4 / 1st resin layer 3 / 3rd resin layer 5 are laminated in this order; 3rd resin layer 5 / 2nd resin layer 4 / 1st resin layer 3 as shown in FIG. / 2nd resin layer 4 / 3rd resin layer 5 are laminated in this order; 3rd resin layer 5 / 2nd resin layer 4 / 1st resin layer 3 / 2nd resin layer 4 as shown in FIG. / A laminated structure in which the first resin layer 3 / the second resin layer 4 / the third resin layer 5 are laminated in this order can be mentioned. Hereinafter, each layer constituting the sheet 1 of the present invention will be described in detail.

[Glass fiber cloth 2]
In the sheet 1 of the present invention, the glass fiber cloth 2 is included in a state of being impregnated with the first resin layer 3 described later. In the sheet 1 of the present invention, the glass fiber cloth 2 contributes to the improvement of the nonflammability of the sheet. The refractive index of the glass fiber cloth 2 is set to be close to the refractive index of the first resin layer 3 described later, whereby the total light transmittance of the sheet 1 of the present invention described later is 80% or more, and the haze 20 It can be configured as% or less. In other words, the configuration in which the total light transmittance of the sheet 1 of the present invention is 80% or more and the haze is 20% or less is at least the refractive index of the glass fiber cloth 2 and the refractive index of the first resin layer 3 described later. Is sufficiently approximate (for example, the difference between the refractive index of the glass fiber cloth 2 and the refractive index of the first resin layer 3 is 0.02 or less).

In the sheet 1 of the present invention, the glass fiber cloth 2 is composed of a plurality of glass fibers. In the glass fiber cloth 2, a plurality of glass fibers are intertwined with each other to form one cloth. Examples of the glass fiber cloth 2 include a glass fiber woven fabric (glass cloth) composed of a plurality of warp threads and a plurality of weft threads. The weaving structure of the glass fiber woven fabric is not particularly limited, and examples thereof include plain weave, satin weave, twill weave, diagonal weave, and ridge weave.

The glass material of the glass fiber constituting the glass fiber cloth 2 is not particularly limited, and for example, a known glass material can be used. Examples of the glass material include non-alkali glass (E glass), acid-resistant alkali-containing glass (C glass), high-strength and high-elasticity glass (S glass, T glass, etc.), alkali-resistant glass (AR glass), and the like. , And preferably, non-alkali glass (E glass) having high versatility can be mentioned. The glass fibers constituting the glass fiber cloth 2 may be made of one kind of glass material, or may be a combination of two or more kinds of glass fibers made of different glass materials. Further, from the viewpoint of improving the transparency, it is preferable to select a glass material which is similar to the refractive index of the first resin layer 3, which will be described later.

The count of the glass fibers constituting the glass fiber cloth 2 is not limited to a specific one as long as the glass fiber cloth 2 can be formed. The count of the glass fiber is preferably 30 tex or less from the viewpoint of further improving the transparency. From the viewpoint of further improving the transparency and reducing the resin weight of the first resin layer 3, which will be described later, to further improve the nonflammability of the sheet 1, the number of the glass fibers is preferably 3 to 30 tex, and 10 to 10 tex. 30 tex is more preferable, and 15 to 30 tex is further preferable.

In the sheet 1, the total weight (g / ^{m 2)} and the total mass of the first resin layer 3 below the glass fiber cloth 2 (g / ^{m 2,} the glass fiber cloth 2 are excluded.) And the total amount of (g / m for ^2), the ratio of the total mass of the glass fiber cloth 2 in the sheet 1 (wt%), when increasing the resin weight in the sheet, to the improve the transparency, and as low a gross calorific value From the viewpoint of further achieving compatibility with the above, 20 to 60% by mass is preferable, 30 to 60% by mass is more preferable, and 40 to 60% by mass is further preferable. Further, as the ratio (mass%) of the total mass (g / m ² ) of the glass fiber cloth 2 in the sheet 1 to the total mass (g / m ² ) of the sheet 1, the transparency is improved and the total heat generation is generated. From the viewpoint of further achieving both a low amount and a low amount, 10 to 50% by mass is preferable, 20 to 40% by mass is more preferable, 20 to 35% by mass is further preferable, and 25 to 33% by mass is particularly preferable. preferable. The mass (g / m ² ) per sheet of the glass fiber cloth 2 is not particularly limited, but is preferably 10 to 150 (g / m ² ), more preferably 40 to 120 (g / m ² ), and 80 to 80 to 120. 120 (g / m ² ) is more preferable. The total mass (g / m ² ) of the glass fiber cloth 2 in the sheet 1 is 10 to 500 (g / m ² ) from the viewpoint of further improving the transparency of the sheet 1 while improving the nonflammability of the sheet 1. ² ) is preferable, 100 to 300 (g / m ² ) is more preferable, and 150 to 250 (g / m ² ) is particularly preferable. Further, the total number of glass fiber cloths in the sheet 1 is 1 to 6, and 2 to 5 sheets are preferable from the viewpoint of further improving the handleability while maintaining excellent transparency and nonflammability. Can be mentioned. The number of glass fiber cloths 2 contained in each layer of the first resin layer 3, which will be described later, includes 1 to 3 and preferably 1 or 2.

The difference in refractive index between the glass fiber cloth 2 and the first resin layer 3 described later is preferably 0.02 or less, more preferably 0.01 or less. The refractive index of the glass fiber cloth 2 is preferably about 1.50 to 1.58, more preferably about 1.53 to 1.58, and even more preferably about 1.54 to 1.57.

The refractive index of the glass fiber cloth 2 is measured according to the B method of JIS K 7142: 2008. Specifically, first, the glass fibers constituting the glass fiber cloth are pulverized to such an extent that the Becke line can be observed when observed at a magnification of 400 times using an optical microscope. Then, using a halogen lamp provided with an interference filter for D-rays as a light source, observing and measuring under the conditions of a magnification of 400 times and a temperature of 23 ° C. using an optical microscope, and refracting the average value of three tests. Let it be the value of the rate. Further, the refractive index of the first resin layer 3 and the second resin layer 4, which will be described later, is measured according to the B method of JIS K 7142: 2008. Specifically, the first resin layer 3 or the second resin layer 4 is pulverized to such an extent that the Becke line can be observed when observed with an optical microscope at a magnification of 400 times. Then, using a halogen lamp provided with an interference filter for D-rays as a light source, observation and measurement are performed under the conditions of a magnification of 400 times and a temperature of 23 ° C. using an optical microscope, and the average value of three tests is refracted. Let it be the value of the rate.

The difference in the Abbe number between the glass fiber cloth 2 and the first resin layer 3 is preferably 30 or less, more preferably 20 or less, still more preferably 10 or less. The Abbe number of the glass fiber cloth 2 is preferably 30 to 80, more preferably 40 to 70, and even more preferably 50 to 65. The Abbe numbers of the first resin layer 3 and the glass fiber cloth 2 are measured as follows.

(Abbe number of the first resin layer 3)
Using the resin constituting the first resin layer 3, a sheet not containing the glass fiber cloth 2 is produced to have the same thickness under the same conditions as when the glass fiber cloth 2 is included, and used as a test piece. The surface of the test piece is 8 mm wide and 20 mm long, and the surface is well polished. According to the JIS K 7142A method, the Abbe refractometer is NAR-2T manufactured by Atago Co., Ltd. Is used to measure the refractive index at a wavelength of 589 nm, with the measurement temperature being 23 ° C. Subsequently, the dispersion value is measured and calculated using the light source as natural light, and the Abbe number is calculated according to the following formula (I).
Abbe number = (refractive index at wavelength 589 nm-1) / dispersion value (I)

(Abbe number of glass fiber cloth 2)
A glass sheet having a width of 8 mm, a length of 20 mm, and a thickness of 5 mm was prepared using the glass material constituting the glass fiber, the surface was well polished, and according to the JIS K 7142A method, it was manufactured by Atago Co., Ltd. as an Abbe refractometer. Using NAR-2T, diiodomethane as a contact liquid, and sodium D-ray having a wavelength of 589 nm as a light source, the refractive index is measured at a wavelength of 589 nm at a measurement temperature of 23 ° C. Subsequently, the dispersion value is measured and calculated using the light source as natural light, and the Abbe number is calculated according to the above formula (I).

The thickness of the glass fiber cloth 2 per sheet is, for example, about 10 to 150 μm, preferably 40 to 120 μm, from the viewpoint of further improving the transparency of the sheet 1 while improving the nonflammability of the sheet 1. It is more preferably about 80 to 100 μm. Further, the glass fiber cloth 2 is easily impregnated efficiently by the first resin layer 3, and the glass volume ratio calculated by the following formula (II) is calculated from the viewpoint of reducing the weight of the resin used for the first resin layer. It is preferably 30% or more, more preferably 40 to 60%. The glass volume fraction can be adjusted, for example, by subjecting the glass fiber cloth to a fiber opening treatment.

Glass volume fraction (%) = (A / (B × C)) × 100 (II)
A: Mass of glass fiber cloth (g / m ² )
B: Specific gravity of the glass material constituting the glass fiber cloth (g / m ³ )
C: Thickness of glass fiber cloth (m)

When the glass fiber 2 exists as a glass fiber fabric, the gap between adjacent warp threads in the glass fiber fabric is 0.5 mm or less and / or the glass fiber from the viewpoint of further improving the nonflammability of the sheet 1. The gap between adjacent wefts in the woven fabric is preferably 0.5 mm or less. The gaps between adjacent warp threads and the gaps between adjacent weft threads in the glass fiber woven fabric are measured and calculated as follows.

<Measuring method of the gap between adjacent warp threads and the gap between adjacent weft threads>
The glass fiber woven fabric is observed from the plane direction with a microscope, and the gaps between adjacent warp threads are arbitrarily measured at 20 points. Then, the average value of the gaps between the adjacent warp threads at the 20 locations is defined as the gap spacing (mm) between the adjacent warp threads. The interval between the gaps between the adjacent wefts is also adjusted in the same manner, and the obtained average value is defined as the interval (mm) between the adjacent wefts.

Further, when the glass fiber cloth 2 is a glass fiber woven fabric, the opening ratio of the glass fiber woven fabric is not particularly limited, but for example, 40% or less can be mentioned, further achieving both transparency and nonflammability of the sheet 1. From the viewpoint, 3 to 30% is preferably mentioned. Further, the aperture ratio can be 15% or more and 30% or less, and can be more than 20% and 27% or less. The aperture ratio is calculated by the following formula (III).

Aperture ratio (%) = (distance between adjacent warp threads (mm) x interval between adjacent weft threads (mm)) / [(25 ÷ warp density (book / 25 mm)) x (25 ÷) Weft density (book / 25 mm))] × 100 ・ ・ ・ (III)

(First resin layer 3)
In the sheet 1 of the present invention, the first resin layer 3 is impregnated with the glass fiber cloth 2 and is formed of a resin composition obtained by curing or solidifying a resin composition containing a resin other than a fluororesin. Further, as described later, the second resin layer 4 is included in a state where the glass fiber cloth is not impregnated. Therefore, at least when the first resin layer 3 and the second resin layer 4 are in contact with each other, the glass fiber cloth 2 is not exposed on the surface of the first resin layer 3, and the glass fiber cloth 2 is not exposed. Is contained in the first resin layer 3. As described above, the first resin layer 3 is selected and set so as to be close to the refractive index of the glass fiber cloth 2, whereby light scattering on the glass fiber surface can be reduced, and the total light transmittance described later is 80%. As described above, the haze can be set to 20% or less.

The first resin layer 3 can be a cured resin composition layer or a thermoplastic resin composition layer. In the case of forming a cured resin composition layer, a cured product (photo-cured resin composition or thermosetting) in which the resin composition is cured by applying energy such as light or heat to the resin composition containing the curable resin. The resin composition is obtained). When the thermoplastic resin composition layer is used, it can be a cured product obtained by drying and solidifying the thermoplastic resin composition.

In the sheet 1 of the present invention, the total concentration of bromine and silicon in the first resin layer 3 is preferably lower than the total concentration of bromine and silicon in the second resin layer 4, which will be described later. As a result, the difference in refractive index between the first resin layer 3 and the glass fiber cloth 2 can be made smaller, and the second resin layer 4 contained in the glass fiber cloth without being impregnated is laminated, and the second resin layer is laminated. By using a resin having a high total concentration of bromine and silicon as No. 4, the low heat generation characteristics of the resin having a high total concentration of bromine and silicon can be fully utilized, and the transparency can be improved when the resin weight is increased. It is possible to further achieve both the low total calorific value and the low total calorific value.

From the viewpoint of further lowering the haze of the sheet 1 of the present invention, the total concentration of bromine and silicon in the first resin layer 3 is, for example, 29% by mass or less, preferably 28% by mass or less. 20% by mass or less is more preferably mentioned, and 16.7% by mass or less is further preferably mentioned. The lower limit of the bromine concentration in the first resin layer 3 is 0% by mass. That is, the first resin layer 3 may not contain bromine and silicon.

In the present invention, the concentrations of bromine and silicon are measured by EDS analysis. Specifically, as illustrated in FIGS. 1 to 3, the cut surface in the thickness direction of the sheet 1 is used as the measurement surface, and the sample thickness (that is, the length in the vertical or horizontal direction of the sheet 1) is 1 cm. As a measurement sample, a measurement sample was used as a device under the trade name JSM-6390A manufactured by JEOL Ltd., and one point was arbitrarily measured near the center in the thickness direction of the layer to be measured, and the bromine concentration and silicon concentration were measured. Measure the value of.

In the sheet 1 of the present invention, the difference (= second resin) between the total concentration (mass%) of bromine and silicon in the first resin layer 3 and the total concentration (mass%) of bromine and silicon in the second resin layer 4 described later. The total concentration of the layer 4 − the total concentration of the first resin layer 3) is, for example, 3% by mass or more, which improves the transparency when the resin weight is increased and lowers the total calorific value. From the viewpoint of further achieving compatibility with the above, 3 to 50% by mass is preferably mentioned, 30 to 50% by mass is more preferably mentioned, and 40 to 50% by mass is particularly preferable.

As the curable resin used for forming the first resin layer 3, the refractive index of the first resin layer 3 and the above-mentioned glass fiber cloth 2 can be approximated from the viewpoint of further improving the transparency of the sheet 1. What can be done is preferable. The curable resin preferably has a curable resin composition that is photocurable. For example, vinyl ester resin, brominated vinyl ester resin, urethane acrylate resin, fluorene acrylate resin, unsaturated polyester resin, and curable acrylic resin. , Epoxy resin and the like. Among them, a curable acrylic resin is more preferable, and a cured resin composition containing an acrylic syrup is particularly preferable, from the viewpoint of further improving the adhesiveness with the third resin layer 5. In the present invention, the acrylic syrup refers to a polymerizable liquid mixture in which a (meth) acrylic acid ester polymer such as polymethyl methacrylate (PMMA) is dissolved in an acrylic monomer such as methyl methacrylate. Among the above acrylic syrups, one or more acrylic acid ester polymers selected from the group consisting of polymethyl methacrylate, methyl methacrylate / methyl acrylate copolymer, and methyl methacrylate / normal butyl acrylate copolymer are methacrylic. Acrylic syrup dissolved in a methyl acrylate monomer is particularly preferable. In this way, when the first resin layer 3 is a cured resin composition containing an acrylic syrup, the adhesion to the film layer 5 is further improved, so that the transparency of the sheet 1 is further improved. preferable.

As the thermoplastic resin used for forming the first resin layer 3, the refractive index of the first resin layer 3 and the glass fiber cloth 2 can be approximated from the viewpoint of further improving the transparency of the sheet 1. Is preferable. Preferred thermoplastic resins include, for example, polyvinyl chloride resin, saturated polyester resin, polyolefin resin, thermoplastic acrylic resin, polycarbonate resin, polyvinyl alcohol resin, ethylene vinyl acetate copolymer, polyamide resin, polyarylate resin and the like. For example, when E glass is used as the glass material of the glass fibers constituting the glass fiber cloth 2, from the viewpoint of further approximating the refractive electrodes of the two, among these, polyvinyl chloride resin, saturated polyester resin, and thermoplastic acrylic Resin or the like is preferable. One type of thermoplastic resin may be used alone, or two or more types having different refractive indexes may be used in combination for the purpose of approximating the refractive index of the glass fiber to be used. In the sheet 1 of the present invention, when the first resin layer 3 is used as the thermoplastic resin composition layer, the first resin layer 3 is impregnated with the thermoplastic resin composition in the form of a sol or dissolved in a solvent and solidified (heated). It is preferable that it is solidified by or drying).

The resin composition constituting the first resin layer 3 shall contain phosphorus from the viewpoint that the maximum heat generation rate does not exceed 200 kW / m ² continuously for 10 seconds or more within 20 minutes from the start of heating. Can be done. As the phosphorus-containing form, for example, among the above-mentioned resins, a resin composition composed of a resin in which a phosphorus atom is introduced as a substituent, or a resin composition obtained by adding a known phosphorus-based flame retardant to the above-mentioned resin. Can be done. Examples of the phosphorus-based flame retardant include a condensed phosphoric acid ester compound such as a non-halogen condensed phosphoric acid ester compound and a halogen-containing condensed phosphoric acid ester compound. From the viewpoint of adjusting the refractive index, the phosphorus-based flame retardant may be non-halogen condensed. It is more preferable to contain a phosphoric acid ester compound. Further, from the viewpoint of further suppressing the bleed-out of the phosphoric acid ester compound, it is more preferable to contain the condensed phosphoric acid ester compound having a molecular weight of 420 or more. Examples of the non-halogen condensed phosphate compound include 1,3-phenylene bis (diphenyl phosphate) [RDP, molecular weight 574.46], bisphenol A bis (diphenyl phosphate) [BDP, molecular weight 692.64], 1,3-. Examples thereof include phenylene bis (dixylenyl) phosphate [molecular weight 686.67] and bisphenol A bis ((bisdimethylphenyl) phosphate) [molecular weight 804.86]. Examples of the halogen-containing condensed phosphoric acid ester compound include 2,2-bis (chloromethyl) trimethylenebis (bis (2chloroethyl) phosphate) [molecular weight 582.99]. These phosphoric acid ester compounds may be used alone or in combination of two or more.

Further, the resin composition constituting the first resin layer 3 can contain an inorganic flame retardant such as antimony trioxide and magnesium hydroxide.

Further, the resin composition constituting the first resin layer 3 may further contain additives such as a curing accelerator, an ultraviolet absorber, a filler, and a photopolymerization initiator. Examples of the ultraviolet absorber include benzotriazole and the like. Examples of the filler include calcium carbonate, silica, talc and the like. Examples of the photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 2-hydroxy-2-methyl-1-phenyl-propane-1-. On, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1-one, 2-hirodoxy-1- {4- [4- (2-hydroxy-) 2-Methyl-propionyl) -benzyl] phenyl} -2-methyl-propane-1-one, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one, 2-benzyl-2 -Dimethylamino-1- (4-morpholinophenyl) -butanone-1,2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl]- Examples thereof include 1-butanone, 2,4,6, -trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and the like. Above all, when a curable acrylic resin is used as the first resin layer 3, 1-hydroxy-cyclohexyl-phenyl-ketone is preferable from the viewpoint of improving transparency. These additives may be used alone or in combination of two or more. When the first resin layer 3 contains an additive, the content thereof is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass.

In the sheet 1 of the present invention, the total mass of the resin composition of the first resin layer 3 (glass fiber cloth 2).
(Mass excluding) is, for example, 20 to 300 g / m ^2, and the compatibility between improving the transparency and making the nonflammability more excellent when the resin weight is increased is further enhanced. From the viewpoint of planning, 100 to 300 g / m ² is preferably mentioned, 150 to 250 g / m ² is more preferably mentioned, and 170 to 220 g / m ² is particularly preferable. The thickness of the first resin layer 3 per layer (thickness including the glass fiber cloth 2) is, for example, 50 to 200 μm, and the transparency is improved when the resin weight is increased. From the viewpoint of further achieving both that and making the nonflammability more excellent, 80 to 170 μm is preferably mentioned, and 80 to 135 μm is more preferably mentioned.

In the sheet 1 of the present invention, the refractive index of the first resin layer 3 is preferably about 1.50 to 1.58, more preferably about 1.53 to 1.58, and further preferably about 1.54 to 1. About 57 can be mentioned.

(Second resin layer 4)
In the sheet 1 of the present invention, the second resin layer 4 is contained in the glass fiber cloth 2 in a non-impregnated state, and contains a resin other than the fluororesin. The total concentration of bromine and silicon in the second resin layer 4 is 30% by mass or more. In the sheet 1 of the present invention, the first resin layer 3 contained in the glass fiber cloth 2 in a state of being impregnated and the second resin layer 4 contained in the glass fiber cloth 2 in a non-impregnated state are laminated separately. However, as the second resin layer 4 contained in the glass fiber cloth 2 without being impregnated, a resin having a high total concentration of bromine and silicon is used. As a result, the sheet 1 of the present invention can fully utilize the low heat generation characteristics of the resin having a high total concentration of bromine and silicon.

The total concentration of bromine and silicon in the second resin layer 4 of the sheet 1 of the present invention is, for example, 31% by mass or more from the viewpoint of further suppressing the total calorific value and further increasing the resin weight. Is preferable, and 35% by mass is preferably mentioned. The upper limit value is not particularly limited, and examples thereof include 60% by mass or less or 55% by mass or less. The bromine concentration in the second resin layer 4 is preferably, for example, 31% by mass or more, preferably 35% by mass, from the viewpoint of further suppressing the total calorific value and further increasing the resin weight. Be done. The upper limit value is not particularly limited, and examples thereof include 60% by mass or less or 55% by mass or less. The silicon concentration in the second resin layer 4 is preferably, for example, 31% by mass or more, preferably 35% by mass, from the viewpoint of further suppressing the total calorific value and further increasing the resin weight. Be done. The upper limit value is not particularly limited, and examples thereof include 60% by mass or less or 55% by mass or less. As another viewpoint, the sheet of the present invention can have a bromine concentration or a silicon concentration of 30% or more in the second resin layer, preferably 35% by mass. The upper limit of the bromine concentration or the silicon concentration in the second resin layer is not particularly limited, and examples thereof include 60% by mass or less or 55% by mass or less.

Examples of the method of including bromine in the second resin layer 4 include a method of using a resin constituting the second resin layer 4 as a substituent and using a resin containing a bromine atom, a method of using a flame retardant containing a bromine atom as a curable resin or a curable resin. Examples thereof include a method of preparing a resin composition added to a thermoplastic resin.

Examples of the resin containing a bromine atom as the substituent include a curable resin or a thermoplastic resin containing a bromine atom as the substituent. Examples of the curable resin containing a bromine atom as a substituent include a brominated epoxy resin, a brominated vinyl ester resin, and a brominated unsaturated polyester resin. Examples of the thermoplastic resin containing a bromine atom as a substituent include a brominated polycarbonate resin, a brominated polyurethane resin, and a brominated polyester resin.

Examples of the flame retardant containing a bromine atom include decabromodiphenyl, tetrabromobisphenol A (TBBA) and its derivatives, bis (pentabromophenyl) ethane, and 1,2-bis (2,4,6-tribromophenoxy). ) Ethan, brominated polystyrene, hexabromocyclododecane, hexabromobenzene, pentabromobenzyl acrylate, pentabromobenzyl acrylate, decabromodiphenyl oxide, octabromodiphenyl oxide, tetrabromodiphenyl oxide and other phenyl oxide flame retardants. Be done. Examples of the resin containing the flame retardant include a resin containing a bromine atom as a substituent, and a curable resin or a thermoplastic resin exemplified in the first resin layer 3.

Examples of the method of including silicon in the second resin layer 4 include a method of using a resin constituting the second resin layer 4 as a main chain or a substituent containing a silicon atom, and a method of curing a flame retardant containing a silicon atom. Examples thereof include a method of preparing a resin composition added to a sex resin or a thermoplastic resin.

Examples of the resin containing a silicon atom as a main chain or a substituent include a transparent silicone resin. Examples of the flame retardant containing a silicon atom include a compound containing RSiO, and R is, for example, an aryl group such as a phenyl group or a xsilyl group, an alkyl group such as a methyl group or a propyl group, an alkenyl group or the like. There is. Generally, it is known as polyorganosiloxanes.

In sheet 1 of the present invention, the total weight of the second resin layer 4, for example, 100 to 300 g / ^{m 2} can be mentioned, 160~250g / ^{m 2} may be preferably mentioned. The thickness of the second resin layer 4 per layer is, for example, 50 to 200 μm, preferably 120 to 150 μm.

In the sheet 1 of the present invention, the difference in refractive index between the glass fiber cloth 2 and the second resin layer 4 is 0.03 or more, and 0.03 to 0.2. The refractive index of the first resin layer 3 and the second resin layer is 0.03 or more, and 0.03 to 0.2.

In addition, while improving the transparency of the sheet 1 of the present invention and reducing the total calorific value, the resin weight of the sheet 1 is increased to improve the mechanical strength. From the viewpoint of increasing the total content of the resins constituting the first resin layer 3 and the second resin layer 4, all the first resin layers 3 contained in the sheet 1 (excluding the mass of the glass fiber cloth 2). ) And the total in the second resin layer 4) are preferably 200 g / m ² or more, more preferably 300 g / m ² or more, and further preferably 350 g / m ² or more. The upper limit of the total content is, for example, 600 g / m ² or less, preferably 500 g / m ² or less, and more preferably 420 g / m ² or less.

While improving the transparency of the sheet 1 of the present invention and reducing the total calorific value, the resin weight of the sheet 1 is further increased to further improve the mechanical strength. The ratio of the total mass of the first resin layer 4 (excluding the mass of the glass fiber cloth 2) to the total mass of the second resin layer 4 (total mass of the first resin layer / second resin layer) from the viewpoint of increasing the total mass. The total mass) is preferably 0.5 to 3, and more preferably 0.8 to 1.3.

[Third resin layer 5]
The sheet 1 of the present invention contains a third resin layer 5 containing a fluororesin on one surface. As a result, weather resistance can be imparted to the sheet 1.

In the present invention, the fluororesin is a polymer (monopolymer or copolymer) having a repeating unit derived from at least one fluorine-containing monomer, and is, for example, polyfluorovinylidene (PVDF) or polyfluor. Vinyl carbonate (PVF), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene / perfluoroalkyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP) ), Ethylene / tetrafluoroethylene copolymer (ETFE), ethylene / tetrafluoroethylene / hexafluoropropylene copolymer, vinylidene fluoride / tetrafluoroethylene copolymer, vinylidene fluoride / hexafluoropropylene copolymer, foot Vinylidene conjugation / pentafluoropropylene copolymer, tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer (THV), vinylidene fluoride / pentafluoropropylene / tetrafluoroethylene copolymer, vinylidene fluoride / perfluoroalkyl Examples include vinyl ether / tetrafluoroethylene copolymer, ethylene / chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride / chlorotrifluoroethylene copolymer. These fluororesins may be used alone or in combination of two or more. Among these fluororesins, one or more compounds selected from the group consisting of PCTFE, PFA, FEP, ETFE, and PVDF may be contained from the viewpoint of providing the sheet 1 of the present invention with more excellent transparency. Preferably, ETFE and PVDF are more preferable from the viewpoint of weather resistance and flexibility.

From the viewpoint of improving the adhesiveness between the third resin layer 5 and the first resin layer 3 or the second resin layer 4, the third resin layer 5 preferably contains PVDF and an acrylic resin. Examples of the acrylic resin include methyl poly (meth) acrylate (PMMA), ethyl poly (meth) acrylate, propyl poly (meth) acrylate, butyl poly (meth) acrylate, and methyl (meth) acrylate. (Meta) butyl acrylate copolymer, ethyl (meth) acrylate- (meth) butyl acrylate copolymer, ethylene- (meth) methyl acrylate copolymer, styrene-methyl acrylate copolymer Such as a resin containing a (meth) acrylic acid ester alone or a copolymer. Above all, PMMA is preferable from the viewpoint of further improving the adhesiveness with the photocurable resin layer 3.

From the viewpoint of further exhibiting the weather resistance of PVDF and the adhesiveness of acrylic resin to the photocurable resin layer 3, the third resin layer 5 has a PVDF-rich surface (that is, the PVDF content is 51% by mass or more). It is preferable that the acrylic resin-rich surface (that is, the acrylic resin content is 51% by mass or more) is included, and the surface that adheres to the photocurable resin layer 3 is the acrylic resin-rich surface. As the mass ratio of PVDF to acrylic resin (PVDF: acrylic resin) on the PVDF rich surface, for example, 51:49 to 95: 5 is preferable, and 60:40 to 90:10 is more preferable. Further, as the mass ratio of PVDF to acrylic resin (PVDF: acrylic resin) on the acrylic resin rich surface, for example, 5:95 to 49:51 is preferable, and 10:90 to 40:60 is more preferable. .. As described above, a method in which the third resin layer 5 includes a PVDF-rich surface (that is, a PVDF content of 51% by mass or more) and an acrylic resin-rich surface (that is, an acrylic resin content of 51% by mass or more). For example, a sheet A which is an alloy of PVDF and an acrylic resin and has a PVDF content of 51% by mass or more and a sheet B having an acrylic resin content of 51% by mass or more are prepared. Examples thereof include a method of joining the sheet A and the sheet B.

The third resin layer 5 has a transmittance of 30% or less, preferably 20% or less, more preferably 15% or less, still more preferably 10% or less at a wavelength of 380 nm measured by a spectrophotometer. This makes it possible to prevent deterioration such as discoloration of the first resin layer 3 or the second resin layer 4 due to ultraviolet rays, and to maintain transparency when used outdoors for a long period of time. Specifically, the transmittance is measured using a spectrophotometer, trade name U-4000 manufactured by Hitachi High-Tech Science Corporation.

In order to make the third resin layer 5 have the above-mentioned transmittance, it is possible to include an ultraviolet shielding agent in the resin composition constituting the third resin layer 5. The ultraviolet shielding agent also includes an ultraviolet absorbing agent.

Examples of the ultraviolet shielding agent include a metal-based ultraviolet shielding agent, a metal oxide-based ultraviolet shielding agent, a benzotriazole-based ultraviolet shielding agent, a benzophenone-based ultraviolet shielding agent, a triazine-based ultraviolet shielding agent, and malon, in addition to the above-mentioned ultraviolet shielding agent. Acid ester-based UV shielding agents, oxalic acid anilide-based UV shielding agents, benzoate-based UV shielding agents, etc. are mentioned, and from the viewpoint of further improving transparency, benzotriazole-based UV shielding agents, benzophenone-based UV shielding agents, triazine-based UV shielding agents, malonic acid ester-based ultraviolet shielding agents, oxalic acid anilide-based ultraviolet shielding agents, and benzoate-based ultraviolet shielding agents are preferable. The content (mass%) of the ultraviolet shielding agent in the third resin layer 5 is not particularly limited, and examples thereof include 1 to 10% by mass and 3 to 8% by mass. These ultraviolet shielding agents may be kneaded into the third resin layer 5 or may be applied to the surface of the third resin layer 5.

The mass of the third resin layer 5 per layer is not particularly limited, but is preferably 22 to 200 g / m ² and 30 to 100 g / m ² from the viewpoint of achieving both transparency and strength. m ² is more preferable, and 50 to 90 g / m ² is even more preferable. The thickness of the third resin layer 5 per layer is not particularly limited, but is preferably 15 to 150 μm, more preferably 22.5 to 75 μm, and even more preferably 35 to 70 μm.

The total light transmittance per layer of the third resin layer 5 is preferably 85% or more, more preferably 85 to 98%, and even more preferably 90 to 96%. The haze per layer of the third resin layer 5 is preferably 15% or less, more preferably 1 to 10%, and even more preferably 2 to 8%. The total light transmittance of the third resin layer 5 is a value that can be measured according to JIS K7361-1: 1997, and the haze is a value that can be measured according to JIS K7136: 2000.

(Physical properties of sheet 1)
The sheet 1 of the present invention has a total light transmittance of 80% or more and a haze of 20% or less. As described above, the configuration in which the total light transmittance of the sheet 1 of the present invention is 80% or more and the haze is 20% or less has at least the refractive index of the glass fiber cloth 2 and the refractive index of the first resin layer 3. It shows that they are sufficiently close to each other (for example, the difference between the refractive index of the glass fiber cloth 2 and the refractive index of the first resin layer 3 is 0.02 or less). The total light transmittance is preferably 90% or more. Further, the haze is preferably 10% or less. The total light transmittance of Sheet 1 is a value obtained by measuring according to JIS K7361-1 1997, and the haze is a value obtained by measuring according to JIS K 7136: 2000.

The thickness of the sheet 1 of the present invention is 300 to 800 μm, preferably 450 to 600 μm. As the mass of the sheet 1 of the present invention, 500 to 1000 g / ^{m 2} can be mentioned, 600~900g / ^{m 2} may be preferably mentioned. The total mass of the resin in the sheet 1, for example, 300 to 700 g / ^{m 2} can be mentioned, 400~700g / ^{m 2} can be mentioned preferably, 450~600g / ^{m 2} can be cited more preferably.

Sheet 1 of the present invention is "4.10.2 Heat-generating test / evaluation method" in "Fireproof performance test / evaluation work method manual" (modified version on March 1, 2014) of the Building Materials Testing Center. In the heat generation test in which the surface of the sheet is irradiated with radiant heat of 50 kW / m ² from the radiant electric heater measured according to the above, the total calorific value is preferably 8 MJ / m ² or less. Further, it is preferable that the maximum heat generation rate of the sheet 1 of the present invention does not exceed 200 kW / m ² continuously for 10 seconds or more after the start of heating in the heat generation test.

In addition, about "4.10.2 heat generation test / evaluation method" in "fireproof performance test / evaluation work method manual" (changed version on March 1, 2014) of general incorporated foundation building materials test center, concrete Is performed according to the contents described in the following test specimens, test equipment and test conditions.

(1) The number of test specimens (sheets) shall be three.
(2) The shape and dimensions of the test piece shall be a square with a side size of 99 mm ± 1 mm.
[Test equipment]
(1) FIG. 4 shows a schematic view of the test apparatus used. The test device is composed of a conical radiant electric heater, an ignition plug, a radiant heat shield plate, a test piece holder, a gas concentration analyzer, an exhaust system capable of measuring gas flow rate, a heat flow meter, and the like.
(2) The radiant electric heater shall be capable of stably irradiating the surface of the test piece with radiant heat of 50 kW / m ² .
(3) The radiant heat shield plate shall be able to protect the test piece from radiant heat before the start of the test.
(4) FIG. 5 shows a schematic view of a test holder and a holding frame included in the test apparatus. The specimen holder is a square with an outer dimension of 106 mm ± 1 mm on a side, a size of 25 mm ± 1 mm in depth, and made of stainless steel with a thickness of 2.15 mm ± 0.25 mm. A square opening of 0.0 mm ± 0.5 mm shall be provided in the center. The holding frame is made of stainless steel having an inner dimension of 111 mm ± 1 mm on a side and a depth of 54 mm ± 1 mm.
(5) The exhaust system shall be equipped with a centrifugal exhaust fan, a hood, a ventilation port, an exhaust duct, an orifice plate flow meter, etc. that function effectively at the test temperature. The distance between the lower end of the hood and the surface of the test piece shall be 210 mm ± 50 mm, and the exhaust system of the exhaust system in that state shall have a flow rate of 0.024 m ³ / s or more converted to standard temperature and standard pressure. .. An orifice with an inner diameter of 57 mm ± 3 mm is provided between the hood and the duct for measuring the exhaust flow rate. For the purpose of collecting exhaust gas, 12 ring samplers with holes having a diameter of 2.2 mm ± 0.1 mm are attached at a position 685 mm ± 15 mm from the hood so that the holes face in the direction opposite to the flow. Further, the temperature of the exhaust gas is measured at the center of the exhaust duct at a position 100 mm ± 5 mm upstream from the orifice. The orifice should be installed in a position that does not affect the flow rate measurement.
(6) The gas analyzer shall be able to continuously and accurately measure the concentrations of oxygen, carbon monoxide, and carbon dioxide in the exhaust gas.
(7) The spark plug shall be capable of supplying electric power from a 10 kV transformer, an inductive coil system, or the like. The distance between the electrodes of the spark shall be 3 mm ± 0.5 mm, and the position of the electrodes shall be 13 mm ± 2 mm on the central axis of the test piece in principle.
(8) As the heat flow meter, a Schmidt-Boulder type capable of measuring up to 100 kW / m ² ± 10 kW / m ² is used. It is assumed that the heat sensing portion of the heat flow meter has a circular shape with a diameter of 12.5 mm and a surface emissivity of 0.95 ± 0.05.
[Test conditions]
(1) The test time shall be 20 minutes after the surface of the test piece is irradiated with radiant heat and the electric spark is activated at the same time. However, the measurement can be terminated when the combustion clearly does not continue.
(2) The test piece is made by wrapping the side surface and the back surface with an aluminum foil having a thickness of 0.025 mm or more and 0.04 mm or less and putting it in a holding frame, and further, on the back surface side, an inorganic fiber (nominal thickness 13 mm, density 65 kg / m) ^After filling ³ ), it shall be pushed into the specimen holder.
(3) During the test, the surface of the test piece is irradiated with radiant heat of 50 kW / m ² from the radiant electric heater.
(4) regulating the exhaust gas flow rate 0.024m ³ /s±0.002m ³ / s.
(5) Until the start of the test, the radiant heat shielding plate prevents the test piece from receiving radiant heat.
(6) Before moving the radiant heat shield plate, set the spark plug in a predetermined position.
[Measurement]
(1) Measure the concentrations of oxygen, carbon monoxide and carbon dioxide at intervals of 5 seconds or less.
(2) The heat generation rate per unit area (kW / m ² ) is calculated by the method shown below, and the total heat generation amount per unit area (MJ / m ² ) is calculated as the heat generation rate from the start to the end of heating. Is calculated by accumulating.

The heat generation rate (q) is calculated according to the following formula.

here,
^{_{V 298 = C (Δp · Te}} ) 1/2 / 350 (: duct flow at 25 ° C.)
E = 17.2 × 10 ³ kJ / m ³
X ⁰ _O2 : Average value of oxygen concentration by baseline measurement for 1 minute X _O2 : Measured value of oxygen concentration The heat generation rate (q ") per unit area is
q "= q / As
here,
As: Initial exposure area of specimen (0.0088 m ² ).
C (orifice coefficient) is the oxygen concentration (X _O2 ) and differential pressure (X _O2 ) when methane is burned at a flow rate corresponding to the heat generation rate of qb = 5 kW ± 0.5 kW in this measurement under the specified exhaust flow velocity. Calculate from Δp) using the following formula.
C = q _b / (Δhc / ro × 1.10) (Te / Δp) ^1/2 (1.105-1.5X _O2 ) / (0.2095-X _O2 )
here,
q _b : Heat generation rate of supplied methane Δhc / ro: 12.54 × 103 kJ / kg in the case of methane
Te: Gas temperature in the exhaust duct (value measured near the two-way Pitot tube)

(Method for Manufacturing Sheet 1 of the Present Invention)
The method for producing the sheet 1 of the present invention is not particularly limited, but for example, the first step of preparing an intermediate 1 contained in a state where the glass fiber cloth 2 is impregnated with the first resin layer 3, the intermediate 1 The second step of laminating the second resin layer 4 to prepare the intermediate 2 and the third step of laminating the third resin layer 5 on the intermediate 2 can be included. Hereinafter, an example in the case of the laminated structure shown in FIG. 1 will be described.

The first step will be described with reference to a case where the resin constituting the first resin layer 3 is a curable resin. In the first step, first, a glass fiber cloth 2 and an uncured curable resin composition to be used as the first resin layer 3 are prepared. The uncured curable resin composition is applied to a process film (for example, PET film), the glass fiber cloth 2 is placed on the applied uncured curable resin composition, and the glass fiber cloth 2 is uncured. Is impregnated with the curable resin composition of. Next, another process film (for example, PET film) is placed on the uncured curable resin composition impregnated in the glass fiber cloth 2, and the first resin is pressed by a roller from above the process film B. Adjust the mass of layer 3. Then, the uncured curable resin composition which is passed through the step PET film B to form the first resin layer 3 is irradiated with light using a black light fluorescent lamp to cure the curable resin composition, and the first resin is cured. The first layer is contained in a state in which one of the above-mentioned laminated process films (process film A for convenience in this example) is peeled off after forming the layer 3 and the process film B / glass fiber cloth 2 is impregnated. An intermediate body 1 having a laminated structure of the resin layer 3 can be obtained. Two pieces of the intermediate 1 are prepared.

The second step will be described with reference to a case where the resin constituting the second resin layer 4 is a curable resin. In the second step, an uncured curable resin to be used as the second resin layer 4 is prepared, and the uncured curable resin is used on three surfaces of the first resin layer of the intermediate 1 obtained in the first step. Apply to the side. Next, on the uncured curable resin to be the second resin layer 4, the other of the obtained intermediate 1 is uncured so that the first resin layer 3 side is the second resin layer 4. It is placed so as to be on the curable resin side, and is pressed by a roller from above the other intermediate body 1 to adjust the mass of the second resin layer 4. Then, the uncured curable resin composition which passes through the other intermediate body 1 to form the second resin layer 4 is irradiated with light using a black light fluorescent lamp to cure the curable resin composition. The second resin layer 4 is formed and laminated. Then, by peeling off the process films B on both surfaces of the second resin layer 4, the first resin layer 3 / the glass fiber cloth 2 is included in the state of being impregnated in the glass fiber cloth 2 without being impregnated. An intermediate body 2 having a laminated structure of the first resin layer 3 contained in the second resin layer 4 / the glass fiber cloth 2 in a state of being impregnated can be obtained.

Regarding the third step, a fluororesin film to be used as the third resin layer 5 is laminated on both sides of the intermediate body obtained in the second step, and the third resin layer is adhered by heating and pressurizing with a heating press machine. 5 / First resin layer 3 included in the state of being impregnated in the glass fiber cloth 2 / Second resin layer 4 included in the state of being impregnated in the glass fiber cloth 2 / First included in the state of being impregnated in the glass fiber cloth 2. A sheet 1 having a laminated structure of 1 resin layer 3 / 3rd resin layer 5 can be obtained.

(Use of Sheet 1 of the present invention)
Since the sheet 1 of the present invention is excellent in transparency and nonflammability, it can be suitably used for a roofing material, a film material, a film ceiling, a lighting cover, etc. of a building.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

The resin composition constituting the first resin layer 3 to be impregnated with the glass fiber cloth 2 has the composition shown in Table 1 and is made of acrylic syrup (trade name "Acrysyllap XD-8005" manufactured by Ryokou Co., Ltd.). Refraction rate 1.550)), a mixture of RDP (trade name "Adecaster PFR" manufactured by ADEKA Co., Ltd.) which is a non-halogen condensed phosphate compound and a photopolymerization initiator (Omnirad 184 manufactured by IGM) (mass ratio (acrylic syrup) : Non-halogen condensed phosphoric acid ester compound: Photopolymerization initiator) = 70:30: 3), brominated vinyl ester (trade name Neopol 8197 manufactured by Nippon Yupica Co., Ltd.), neopentyl glycol diacrylate (manufactured by Nippon Yupica Co., Ltd., A mixture of a molecular weight 212) and a photopolymerization initiator (Omnirad 184 manufactured by IGM) (mass ratio (vinyl bromide ester: neopentyl glycol diacrylate: photopolymerization initiator) = 67: 33: 3) was used. The resin composition constituting the second resin layer 4 contained in the glass fiber cloth 2 without being impregnated has the composition shown in Table 1 and is a brominated vinyl ester resin (trade name Neopol manufactured by Nippa Corporation). A mixture of 8197) and a photopolymerization initiator (Omnirad 184 manufactured by IGM) and a silicone resin adhesive material (trade name NSH-50 manufactured by Nippa Corporation, 50 μm thick) in which a release PET film was laminated on both sides were used. The amount of the photopolymerization initiator was 3 parts by mass with respect to 100 parts by mass of the brominated vinyl ester resin. The third resin layer 5 includes a sheet containing PVDF and an acrylic resin (a sheet A which is an alloy of PVDF and PMMA and has a PVDF content of 80% by mass and a PMMA content of 20% by mass). A sheet (manufactured by Denka Co., Ltd., trade name "Denka DX Film DX-14S0250", thickness 50 μm, mass) formed by joining sheet B having a PVDF content of 20% by mass and a PMMA content of 80% by mass. 68 g / m ² , a transmittance of 10% at a wavelength of 380 nm, a total light transmittance (JIS K 7105: 1981) 92%, and a haze (JIS K 7105: 1981) 5%) were used.

<Example 1>
(Preparation of glass fiber cloth)
An air jet loom using the trade name "ECE225 1/0 1Z" (average filament diameter 7.0 μm, average filament number 200, twist number 1.0Z, count 22.5tex) manufactured by Unitika Glass Fiber Co., Ltd. as warp and weft. A plain weave glass fiber woven fabric having a warp density of 60 threads / 25 mm and a weft density of 57 threads / 25 mm was obtained. Then, the spinning sizing agent and the weaving sizing agent adhering to the obtained glass fiber woven fabric were removed by heating at 400 ° C. for 30 hours. Then, the surface treatment agent silane coupling agent (S-350: N-vinylbenzyl-aminoethyl-γ-aminopropyltrimethoxysilane (hydrochloride) Chisso Co., Ltd.) was adjusted to a concentration of 15 g / L and squeezed with a padder roll. After that, it was dried and cured at 120 ° C. for 1 minute. Then, the glass fiber woven fabric was subjected to widening treatment while the tension of the glass fiber woven fabric was set to 100 N / m in the warp direction by water flow processing at a pressure of 1.5 MPa to obtain a glass fiber woven fabric to be used as the glass fiber cloth 2. The obtained glass fiber woven fabric had a warp density of 60 threads / 25 mm, a weft density of 57 threads / 25 mm, a thickness of 90 μm, a mass of 105 g / m ² , and a refractive index of 1.561. The gap between the adjacent warp threads in the glass fiber woven fabric and the gap between the adjacent weft threads in the glass fiber woven fabric were 0.5 mm or less. Two pieces of the glass fiber woven fabric were prepared.

(Formation of First Resin Layer 3)
A curable resin composition composed of the acrylic syrup shown in Table 1 as the first resin layer 3 was applied onto one surface of the PET film used as the process film. Next, one sheet of the obtained glass fiber cloth 2 is placed on the curable resin composition to be the first resin layer 3, and the mixture is allowed to stand for 1 minute to allow the above acrylic syrup in the gap of the glass fiber cloth 2. It was impregnated with a curable resin composition comprising. Next, another PET film used as the process film was placed on the curable resin composition composed of the acrylic syrup, and the mass of the first resin layer 3 was 105 g / m ^{2 by a} roller from above the PET film. Pressurized so that After that, a black light fluorescent lamp (trade name FL15BLB manufactured by Toshiba Corporation) was used to irradiate a curable resin composition composed of acrylic syrup as the first resin layer 3 through the process PET film with light (light irradiation condition: integration). The curable resin composition was cured with a light amount of 200 mJ / cm ² ) to form the first resin layer 3, and then the laminated step PET film was peeled off to obtain an intermediate 1. In the obtained intermediate 1, the gap between the glass fibers of the glass fiber cloth 2 is impregnated with the first resin layer 3 (cured product of the resin composition) made of acrylic syrup without exposing the glass fibers. It was. Two pieces of the intermediate 1 were prepared.

(Lamination of the second resin layer 4)
The brominated vinyl ester resin composition shown in Table 1 as the second resin layer 4 contained in the glass fiber cloth 2 without being impregnated is applied to one surface of one of the obtained intermediates 1. did. Next, on the brominated vinyl ester resin composition, the other of the obtained intermediates 1 is placed, and from the brominated vinyl ester resin composition by a roller from above the other intermediate 1. The pressure was applied so that the mass of the second resin layer 4 was 184 g / m ² . Then, a black light fluorescent lamp (trade name FL15BLB manufactured by Toshiba Corporation) is used to irradiate the brominated vinyl ester resin composition which passes through the other intermediate 1 to form the second resin layer 4 (light irradiation conditions). : Cumulative light amount 200 mJ / cm ² ), the brominated vinyl ester resin composition is cured to form the second resin layer 4, and the first resin layer 3 / glass contained in the glass fiber cloth 2 in a state of being impregnated. An intermediate body 2 having a laminated structure of a second resin layer 4 contained in the fiber cloth 2 without being impregnated and a first resin layer 3 contained in the glass fiber cloth 2 in a state of being impregnated was obtained.

(Lamination of the third resin layer 5)
Next, the obtained intermediate body 2 is made of two sheets containing the above-mentioned PVDF and acrylic resin, and the surface of both of the sheets that adheres to the intermediate body 2 is the sheet B side (that is, the acrylic resin rich surface). By sandwiching the cloth and pressing it with a heating press machine under the conditions of a temperature of 160 ° C., a press pressure of 10 kgf / cm ² , and a time of 5 minutes, the intermediate body 2 and a sheet containing PVDF and acrylic resin are adhered to each other. 3 The state of being impregnated with the first resin layer 3 / the state of being impregnated with the glass fiber cloth 2 and the second resin layer 4 / the state of being impregnated with the state of being impregnated with the glass fiber cloth 2 The sheet of the present invention having a laminated structure of the first resin layer 3 / the third resin layer 5 contained in the above was obtained.

<Example 2>
(Preparation of glass fiber cloth)
Two sheets of the same glass fiber woven fabric as the glass fiber woven fabric prepared in Example 1 were prepared.

(Formation of First Resin Layer 3)
A curable resin composition composed of the acrylic syrup shown in Table 1 as the first resin layer 3 was applied onto one surface of the PET film used as the process film. Next, two sheets of the obtained glass fiber cloth 2 are placed on the curable resin composition to be the first resin layer 3, and the mixture is allowed to stand for 1 minute to allow the above acrylic syrup in the gap between the glass fiber cloth 2. It was impregnated with a curable resin composition comprising. Next, another PET film used as the process film was placed on the curable resin composition composed of the acrylic syrup, and the mass of the first resin layer 3 was 180 g / m ^{2 by a} roller from above the PET film. Pressurized so that After that, a black light fluorescent lamp (trade name FL15BLB manufactured by Toshiba Corporation) was used to irradiate a curable resin composition composed of acrylic syrup as the first resin layer 3 through the process PET film with light (light irradiation condition: integration). The curable resin composition was cured with a light amount of 200 mJ / cm ² ) to form the first resin layer 3, and then the laminated step PET film was peeled off to obtain an intermediate 1. In the obtained intermediate 1, the gap between the glass fibers of the glass fiber cloth 2 is impregnated with the first resin layer 3 (cured product of the resin composition) made of acrylic syrup without exposing the glass fibers. It was.

(Lamination of the second resin layer 4)
The release film of the silicone resin adhesive material described above was peeled off on both sides, sandwiched between the 12 intermediates obtained above, pressed with a press machine under the conditions of a press thickness of 10 kgf / cm ² and a time of 1 minute, and applied to a glass fiber cloth 2. Lamination of the second resin layer 4 contained in the non-impregnated state / the first resin layer 3 contained in the glass fiber cloth 2 impregnated state / the second resin layer 4 contained in the glass fiber cloth 2 in a non-impregnated state. The intermediate body 2, which is a structure, was obtained.

(Lamination of the third resin layer 5)
Next, the obtained intermediate body 2 is made of two sheets containing the above-mentioned PVDF and acrylic resin, and the surface of both of the sheets that adheres to the intermediate body 2 is the sheet B side (that is, the acrylic resin rich surface). The fiberglass is sandwiched and pressed with a heating press machine under the conditions of a temperature of 160 ° C., a press pressure of 10 kgf / cm ² , and a time of 5 minutes, and the intermediate 2 and a sheet containing PVDF and acrylic resin are adhered to each other. 3 The state of being impregnated with the first resin layer 3 / the state of being impregnated with the second resin layer 4 / the state of being impregnated with the glass fiber cloth 2 included in the state of being impregnated with the resin layer 5 / the state of being impregnated with the glass fiber cloth 2. The sheet of the present invention having a laminated structure of the second resin layer 4 / the third resin layer 5 contained in the first resin layer 3 / the glass fiber cloth 2 without being impregnated with the above was obtained.

<Example 3>
Weaving with an air jet loom using the trade name "D450 1/01 1Z" (average filament diameter 5.0 μm, average filament number 200, twist number 1Z) manufactured by Unitika Glass Fiber Co., Ltd. as the warp and weft, the warp density is high. A plain weave glass fiber woven fabric having 59 threads / 25 mm and a weft density of 47 threads / 25 mm was obtained. Then, the spinning sizing agent and the weaving sizing agent adhering to the obtained glass fiber woven fabric were removed by heating at 400 ° C. for 30 hours. Then, the surface treatment agent silane coupling agent (S-350: N-vinylbenzyl-aminoethyl-γ-aminopropyltrimethoxysilane (hydrochloride) Chisso Co., Ltd.) was adjusted to a concentration of 15 g / L and squeezed with a padder roll. Then, it was dried and cured at 120 ° C. for 1 minute to obtain a glass fiber woven fabric to be made into glass fiber 2. The obtained glass fiber woven fabric had a thickness of 60 μm, a mass of 50 g / m ² , and a refractive index of 1.561. The gap between the adjacent warp threads in the glass fiber woven fabric and the gap between the adjacent weft threads in the glass fiber woven fabric were 0.5 mm or less. Four pieces of the glass fiber woven fabric were prepared.

(Formation of First Resin Layer 3)
A curable resin composition composed of the acrylic syrup shown in Table 1 as the first resin layer 3 was applied onto one surface of the PET film used as the process film. Next, two sheets of the obtained glass fiber cloth 2 are placed on the curable resin composition to be the first resin layer 3, and the mixture is allowed to stand for 1 minute to allow the above acrylic syrup in the gap between the glass fiber cloth 2. It was impregnated with a curable resin composition comprising. Next, another PET film used as the process film was placed on the curable resin composition composed of the acrylic syrup, and the mass of the first resin layer 3 was adjusted to 120 g / m ^{2 by a} roller from above the PET film. Pressurized so that After that, a black light fluorescent lamp (trade name FL15BLB manufactured by Toshiba Corporation) was used to irradiate a curable resin composition composed of acrylic syrup as the first resin layer 3 through the process PET film with light (light irradiation condition: integration). The curable resin composition was cured with a light amount of 200 mJ / cm ² ) to form the first resin layer 3, and then the laminated step PET film was peeled off to obtain an intermediate 1. In the obtained intermediate 1, the gap between the glass fibers of the glass fiber cloth 2 is impregnated with the first resin layer 3 (cured product of the resin composition) made of acrylic syrup without exposing the glass fibers. It was. Two pieces of the intermediate 1 were prepared.

(Lamination of the second resin layer 4)
The brominated vinyl ester resin composition shown in Table 1 as the second resin layer 4 contained in the glass fiber cloth 2 without being impregnated is applied to one surface of one of the obtained intermediates 1. did. Next, the other of the obtained intermediates 1 is placed on the brominated vinyl ester resin composition, and the brominated vinyl ester resin composition is rolled from above the other intermediate 1 with a roller. The pressure was applied so that the mass of the second resin layer 4 was 136 g / m ² . Then, a black light fluorescent lamp (trade name FL15BLB manufactured by Toshiba Corporation) is used to irradiate the brominated vinyl ester resin composition which passes through the other intermediate 1 to form the second resin layer 4 (light irradiation conditions). : Cumulative light amount 200 mJ / cm ² ), the brominated vinyl ester resin composition is cured to form the second resin layer 4, and the first resin layer 3 / glass contained in the glass fiber cloth 2 in a state of being impregnated. An intermediate body 2 having a laminated structure of a second resin layer 4 contained in the fiber cloth 2 without being impregnated and a first resin layer 3 contained in the glass fiber cloth 2 in a state of being impregnated was obtained.

(Lamination of the third resin layer 5)
Next, the obtained intermediate body 2 is made of two sheets containing the above-mentioned PVDF and acrylic resin, and the surface of both of the sheets that adheres to the intermediate body 2 is the sheet B side (that is, the acrylic resin rich surface). By sandwiching the cloth and pressing it with a heating press machine under the conditions of a temperature of 160 ° C., a press pressure of 10 kgf / cm ² , and a time of 5 minutes, the intermediate body 2 and a sheet containing PVDF and acrylic resin are adhered to each other. 3 The state of being impregnated with the first resin layer 3 / the state of being impregnated with the glass fiber cloth 2 and the second resin layer 4 / the state of being impregnated with the state of being impregnated with the glass fiber cloth 2 The sheet of the present invention having a laminated structure of the first resin layer 3 / the third resin layer 5 contained in the above was obtained.

<Example 4>
(Preparation of glass fiber cloth)
Two sheets of the same glass fiber woven fabric as the glass fiber woven fabric prepared in Example 1 were prepared.

(Formation of First Resin Layer 3)
A curable resin composition composed of the brominated vinyl ester shown in Table 1 as the first resin layer 3 was applied onto one surface of a PET film used as a process film. Next, two sheets of the obtained glass fiber cloth 2 are placed on the curable resin composition to be the first resin layer 3, and the mixture is allowed to stand for 1 minute to bromide the gaps of the glass fiber cloth 2. It was impregnated with a curable resin composition composed of vinyl ester. Next, another PET film used as a process film is placed on a curable resin composition composed of the brominated vinyl ester, and the mass of the first resin layer 3 is 200 g / m with a roller from above the PET film. ^The pressure was increased to ² . After that, a black light fluorescent lamp (trade name FL15BLB manufactured by Toshiba Corporation) was used to irradiate a curable resin composition composed of a brominated vinyl ester which passes through the step PET film to form the first resin layer 3 (light irradiation conditions). : The integrated light amount was 200 mJ / cm ² ) to cure the curable resin composition to form the first resin layer 3, and then the laminated step PET film was peeled off to obtain an intermediate 1. In the obtained intermediate 1, the first resin layer 3 (cured product of the resin composition) made of brominated vinyl ester is impregnated in the gaps between the glass fibers of the glass fiber cloth 2 without exposing the glass fibers. It had been.

(Lamination of the second resin layer 4)
The release film of the silicone resin adhesive material described above was peeled off on both sides, sandwiched between the 12 intermediates obtained above, pressed with a press machine under the conditions of a press thickness of 10 kgf / cm ² and a time of 1 minute, and applied to a glass fiber cloth 2. Lamination of the second resin layer 4 contained in the non-impregnated state / the first resin layer 3 contained in the glass fiber cloth 2 impregnated state / the second resin layer 4 contained in the glass fiber cloth 2 in a non-impregnated state. The intermediate body 2, which is a structure, was obtained.

(Lamination of the third resin layer 5)
Next, the obtained intermediate body 2 is sandwiched between two sheets containing PVDF and an acrylic resin so that the surface of both of the sheets that adheres to the intermediate body 2 is the sheet B side (that is, the acrylic resin rich surface). , Pressed with a heating press machine at a temperature of 160 ° C., a press pressure of 10 kgf / cm ² , and a time of 5 minutes, and by adhering the intermediate body 2 and a sheet containing PVDF and acrylic resin, the third resin Layer 5 / First resin layer 3 included in the glass fiber cloth 2 impregnated / Second resin layer 4 included in the glass fiber cloth 2 without being impregnated / Glass fiber cloth 2 impregnated The sheet of the present invention having a laminated structure of the second resin layer 4 / the third resin layer 5 contained in the first resin layer 3 / the glass fiber cloth 2 without being impregnated was obtained.

In Examples and Comparative Examples, the weaving density of the glass fiber cloth was measured and calculated according to JIS R 3420 2013 7.9. The thickness of the glass fiber cloth was measured and calculated according to the JIS R 3420 2013 7.10.1A method. The mass of the glass fiber cloth was measured and calculated according to JIS R 3420 2013 7.2. The refractive indexes of the glass fiber cloth 2, the first resin layer 3, and the second resin layer 4 were measured and calculated by the above-mentioned method. The Abbe numbers of the glass fiber cloth 2 and the first resin layer 3 were measured and calculated by the above method. The following evaluation was performed after the sheet 1 was manufactured and left indoors for one week.

The bromine concentration and the silicon concentration were measured by the method described above.

The total light transmittance and haze of Sheet 1 and "4.10" of Sheet 1 in the "Fireproof Performance Test / Evaluation Work Method Manual" (revised March 1, 2014) of the Building Materials Testing Center. .2 Heat generation test / evaluation method ”, the total heat generation amount (MJ / m ² ) and heat generation rate 200 kW / in the heat generation test in which the surface of the sheet is irradiated with radiant heat of 50 kW / m ² from the radiant electric heater. The time (S) exceeding m ² was measured and calculated by the method described above. Further, the presence or absence of a through hole was determined for the sheet 20 minutes after the start of heating according to the above "4.10.2 Heat generation test / evaluation method".

The results of each evaluation are shown in Table 1.

Claims (4)

With at least one fiberglass cloth,
A first resin layer that is impregnated in the glass fiber cloth and contains a resin other than fluororesin,
A second resin layer that is contained in the glass fiber cloth without being impregnated and contains a resin other than fluororesin,
A sheet containing a third resin layer containing a fluororesin.
The total concentration of bromine and silicon in the second resin layer is 30% by mass or more.
The third resin layer is contained on at least one surface of the sheet,
Total light transmittance is 80% or more, haze is 20% or less,
Sheet. The sheet according to claim 1, which has a thickness of 400 μm or more. The sheet according to claim 1 or 2, wherein the glass fibers constituting the glass fiber cloth have a refractive index of 1.53 to 1.58. The sheet according to any one of claims 1 to 3, wherein the total mass of the glass fiber cloth in the sheet is 150 to 250 g / m ² .