JP5950066B1 - Transparent composite sheet - Google Patents

Abstract

Disclosed is a transparent composite sheet that is easy to impregnate a glass fiber fabric with a vinyl chloride resin, is excellent in whitening resistance and peel resistance, and has transparency and flame resistance. A transparent composite sheet includes a glass fiber fabric and a resin composition impregnated therein. The glass fiber which comprises a glass fiber fabric is SiO252.0-56.0 mass%, B2O35.0-10.0 mass%, Al2O312.0-16.0 mass%, CaO and MgO in total 20-25 And 0 to 1.0% by mass in total of Li 2 O, K 2 O and Na 2 O. The glass fiber fabric has an air permeability of 50 to 200 cm <3> / cm <2> / second, and methacrylic silane or cationic silane is attached to the surface. A resin composition contains 45.0-75.0 mass% vinyl chloride-vinyl acetate copolymer resin with respect to the total mass. The transparent composite sheet has a total light transmittance of 85% or more and a haze of 20% or less. [Selection] Figure 1

Description

The present invention relates to a transparent composite sheet obtained by impregnating a glass fiber fabric with a resin composition.

  Conventionally, a transparent composite sheet including a glass fiber fabric impregnated with a resin composition has been used as a membrane material for buildings such as smoke barriers, ceiling lighting shades, and space partitions. In the transparent composite sheet, it is known to use a vinyl chloride resin as a resin composition to be impregnated into the glass fiber fabric (see, for example, Patent Documents 1 to 4).

  According to the transparent composite sheet using the glass fiber fabric impregnated with the vinyl chloride resin, excellent transparency and flame resistance (flame extinguishing) can be obtained.

Japanese Patent Laying-Open No. 2015-77756 International Publication No. 2009/063809 Japanese Patent Application Laid-Open No. 2014-077653 JP 2011-213093 A

  However, the transparent composite sheet is disadvantageous in that the vinyl chloride resin is less likely to be impregnated into the glass fiber fabric and the production efficiency may be lowered.

  Further, in the transparent composite sheet using the glass fiber fabric impregnated with the vinyl chloride resin, whitening occurs at the time of bending, or the vinyl chloride resin and the glass fiber fabric are peeled off due to change over time. There is an inconvenience that the handleability is low.

  In particular, it has been difficult to process the transparent composite sheet into an accordion curtain that is easy to open and close and has excellent space-saving properties during folding because of whitening that occurs during folding.

  Therefore, the present invention eliminates such inconvenience, and the glass fiber fabric is easily impregnated with vinyl chloride resin, has excellent whitening resistance during bending, excellent peel resistance (peeling resistance) due to aging, and transparency. An object of the present invention is to provide a transparent composite sheet having flameproofness, and a flameproof accordion curtain using the transparent composite sheet.

In order to achieve this object, the transparent composite sheet of the present invention is a transparent composite sheet comprising a glass fiber fabric and a resin composition impregnated in the glass fiber fabric, the glass constituting the glass fiber fabric. _fibers, SiO 2 52.0-56.0 _{wt%, B} 2 O 3 5.0 to 10.0 _{wt%, Al} 2 O 3 12.0 to 16.0 wt%, in total of the CaO and MgO 20 to 25% by mass and a composition containing 0 to 1.0% by mass in total of Li ₂ O, K ₂ O, and Na ₂ O, and the glass fiber fabric has a composition of 50 to 200 cm ³ / cm ^2. The glass fiber fabric has methacrylic silane or cationic silane as a silane coupling agent on the surface thereof, and the resin composition has 45.0% of its total mass. ~ 75.0 mass% vinyl chloride They include acid vinyl copolymer resin, salt vinyl - vinyl acetate copolymer resin is composed of a constitutional unit 60% to 95% derived from vinyl chloride monomer, and constituent units 5-40% derived from vinyl acetate monomer, the total The light transmittance is 85% or more, and the haze is 20% or less.

In the transparent composite sheet of this invention, it is a glass fabric woven using the glass fiber provided with the said composition, Comprising: It has an air permeability of 50-200 cm < ³ > / cm < ² > / sec, and methacryl is used as a silane coupling agent on the surface. A resin composition comprising 45.0 to 75.0% by mass of a vinyl chloride-vinyl acetate copolymer resin based on the total mass of the resin composition with respect to a glass fiber fabric to which silane or cationic silane is adhered. Impregnate. As a result, the glass fiber fabric can be easily impregnated with the resin composition.

  Further, according to the transparent composite sheet of the present invention in which the glass fiber fabric is impregnated with the resin composition, the whitening resistance at the time of bending processing, the peel resistance (peeling resistance) due to change over time, excellent transparency, It can be provided with flameproofness.

  Moreover, the transparent composite sheet of this invention can be equipped with the total light transmittance of 85% or more and a haze of 20% or less by setting it as the said structure.

If the air permeability is less than 50 cm ³ / cm ² / sec, the glass fiber fabric is difficult to impregnate the resin composition, and whitening resistance cannot be obtained when the obtained transparent composite sheet is bent. On the other hand, when the air permeability of the glass fiber fabric exceeds 200 cm ³ / cm ² / sec, the peel resistance of the resin composition against the glass fiber fabric cannot be obtained over time, and the transparent composite sheet is burnt. In such a case, flame burnout occurs, and thus the obtained transparent composite sheet cannot be imparted with nonflammability.

  Further, when the silane coupling agent other than methacryl silane or cationic silane is attached to the surface of the glass fiber fabric, it is difficult to impregnate the glass fiber fabric with the resin composition.

  The resin composition has a peel resistance of the resin composition with respect to the glass fiber fabric when the content of the vinyl chloride-vinyl acetate copolymer resin is less than 45.0% by mass with respect to the total mass of the resin composition. I can't. On the other hand, the resin composition is difficult to impregnate into the glass fiber fabric when the content of the vinyl chloride-vinyl acetate copolymer resin exceeds 75.0% by mass with respect to the total mass of the resin composition. Whitening resistance cannot be obtained when the sheet is bent.

  By the way, due to the irregularities on the surface of the glass fiber fabric derived from the fabric structure, there may be a case where minute irregularities remain on the surface of the glass fiber fabric impregnated with the resin composition. Then, it is preferable that the transparent composite sheet of this invention is equipped with the soft vinyl chloride resin film laminated | stacked on the upper surface and lower surface of the said glass fiber fabric impregnated with the said resin composition.

  The transparent composite sheet of the present invention is provided with the vinyl chloride resin film, whereby the surface irregularities of the glass fiber fabric are masked, and a transparent composite sheet having higher surface smoothness can be obtained. Since the transparent composite sheet has high surface smoothness, light diffusion on the surface of the transparent composite sheet can be suppressed and haze can be reduced, so that higher transparency can be obtained.

  At this time, the transparent composite sheet of the present invention includes a difference in refractive index between the glass fiber fabric and the resin composition, a difference in refractive index between the glass fiber fabric and the soft vinyl chloride resin film, and the resin composition. The difference in refractive index from the soft vinyl chloride resin film is preferably less than 0.010. The transparent composite sheet of this invention can obtain the outstanding transparency because each said refractive index difference is less than 0.010.

  In the transparent composite sheet of the present invention, the vinyl chloride-vinyl acetate copolymer resin is composed of 70 to 95% of a structural unit derived from a vinyl chloride monomer and 5 to 30% of a structural unit derived from a vinyl acetate monomer. It is preferable.

  In the transparent composite sheet of the present invention, when the composition of the vinyl chloride-vinyl acetate copolymer resin is out of the above range, the glass fiber fabric may not be sufficiently impregnated with the resin composition. In addition, the peel resistance of the resin composition may not be sufficiently obtained with respect to the glass fiber fabric, and the whitening resistance may not be sufficiently obtained when the obtained transparent composite sheet is bent.

  The flameproof accordion curtain according to the present invention includes the transparent composite sheet.

  Since the flameproof accordion curtain of the present invention includes the transparent composite sheet, whitening does not occur even when it is folded, so that the appearance is good, and the transparency, nonflammability, and prevention can be confirmed over the curtain. Since it has flame resistance, it is particularly excellent as a flameproof curtain.

The table | surface which shows the physical property of the transparent composite sheet of Examples 1-3. The table | surface which shows the physical property of the transparent composite sheet of Comparative Examples 1-3. The table | surface which shows the physical property of the transparent composite sheet of Comparative Examples 4-7.

  Next, embodiments of the present invention will be described in more detail.

The transparent composite sheet of the present embodiment is a transparent composite sheet containing a glass fiber fabric and a resin composition impregnated in the glass fiber fabric, and the glass fiber constituting the glass fiber fabric is made of SiO ₂ 52. 0 to 56.0 _{wt%, B} 2 O 3 5.0 to 10.0 _{wt%, Al} 2 O 3 12.0 to 16.0 wt%, 20-25 wt% of the CaO and MgO in total, and , Li ₂ O, K ₂ O, and Na ₂ O in a total amount of 0 to 1.0% by mass, and the glass fiber fabric has an air permeability of 50 to 200 cm ³ / cm ² / sec. In the glass fiber fabric, methacryl silane or cationic silane is attached to the surface, and the resin composition is 45.0 to 75.75 with respect to its total mass (total mass of the resin composition). Contains 0% by weight vinyl chloride-vinyl acetate copolymer resin Vinyl acetate copolymer resin, a constituent unit 60% to 95% derived from vinyl chloride monomer, consists of a structural unit 5-40% derived from vinyl acetate monomer, the total light transmittance of 85% or more - salt vinyl Yes, the haze is 20% or less, preferably 10% or less. The transparent composite sheet of this embodiment contains a dye or pigment in the resin composition in order to make it difficult to perceive the presence of the sheet, and to reduce the feeling of pressure given to the person by the presence of the sheet, particularly in a closed space. It is preferably a colorless and transparent transparent composite sheet.

  The composition of the glass fiber constituting the glass fiber woven fabric is derived from each component using a fluorescent X-ray analyzer (for example, Simulix type 12 (trade name) manufactured by Rigaku Corporation) with respect to the glass fiber woven fabric. It can be calculated by obtaining the intensity of each peak and comparing each peak intensity. Further, for B, which is a light element, in order to obtain higher measurement accuracy, an object obtained by pulverizing and pulverizing a glass fiber fabric is measured, and an ICP emission spectroscopic analyzer (for example, manufactured by Seiko Electronics Industry Co., Ltd.) is used. It can also be measured using SPS4000 (trade name). In addition, as a measuring object used for the measurement of the composition of the glass fiber constituting the glass fiber fabric, for example, the glass fiber fabric remaining after the transparent composite sheet is heated at 600 ° C. for 24 hours to remove the resin can be used. .

  The total light transmittance is measured according to JIS K7361-1 (Plastic—How to determine the total light transmittance of a transparent material).

  The haze is measured according to JIS K7136 (Plastic—How to determine haze of transparent material).

The transparent composite sheet of the present embodiment can contain 1 to 2 glass fiber fabrics, but preferably 1 sheet. At this time, the thickness of the glass fiber fabric is, for example, 10 to 100 μm, preferably 15 to 90 μm, more preferably 20 to 80 μm, and further preferably 30 to 70 μm. Moreover, the mass per unit area of the said glass fiber fabric is 10-95 g / m < ² >, for example, Preferably it is 15-85 g / m < ² >, More preferably, it is 20-75 g / m < ² >, More preferably. Is 30 to 65 g / m ² , particularly preferably 35 to 60 g / m ² , and most preferably 40 to 53 g / m ² . The thickness and the mass per unit area of the glass fiber fabric are measured according to JIS R 3420 (Glass fiber general test method). Here, as a measurement target of the thickness and the mass per unit area of the glass fiber fabric, for example, the glass fiber fabric remaining after the resin is removed by heating the transparent composite sheet at 600 ° C. for 24 hours can be used. .

  The content of the glass fiber fabric in the transparent composite sheet of the present embodiment is, for example, 7 to 75% by mass, preferably 8 to 25% by mass, and more preferably 9%, based on the total mass of the transparent composite sheet. It is -20 mass%, More preferably, it is 10-15 mass%. Moreover, the ratio of the thickness of the said glass fiber fabric with respect to the total thickness of the transparent composite sheet of this embodiment is 8 to 80%, for example, Preferably it is 10 to 40%, More preferably, it is 12 to 30%. More preferably, it is 15 to 25%.

In the transparent composite sheet of the present embodiment, the mass per unit area of the resin composition impregnated in the glass fiber fabric is, for example, 15 to 170 g / m ² , preferably 20 to 80 g / m ² . , more preferably 30~70g / ^{m 2,} more preferably from 40 to 60 g / ^{m 2.} In addition, the mass per unit area of the resin composition is determined from the mass per unit area of the transparent composite sheet, for example, by heating the transparent composite sheet at 600 ° C. for 24 hours and removing the resin, and then remaining glass fiber fabric. It can be calculated by subtracting the mass per unit area. When the transparent composite sheet includes a soft vinyl chloride resin film, the mass per unit area of the transparent composite sheet is measured in advance, and then the transparent composite sheet dissolves the resin composition but dissolves the soft vinyl chloride resin film. Soak the resin composition in an organic solvent by immersing it in an organic solvent (for example, acetone or methyl ethyl ketone), and then determine the mass per unit area of the glass fiber fabric and the soft vinyl chloride resin film that remain without being eluted. It can be calculated by measuring and subtracting the sum of the mass per unit area of the glass fiber fabric and the soft vinyl chloride resin film from the mass per unit area of the transparent composite sheet.

Moreover, the mass per unit area of the transparent composite sheet of this embodiment is 100-700 g / m < ² >, for example, Preferably it is 150-600 g / m < ² >, More preferably, it is 200-500 g / m < ² >. More preferably, it is 250 to 400 g / m ² . Moreover, the thickness of the transparent composite sheet of this embodiment is 50-650 micrometers, for example, Preferably it is 100-500 micrometers, More preferably, it is 150-400 micrometers, More preferably, it is 200-300 micrometers. The mass per unit area of the transparent composite sheet can be calculated from the mass of the measurement sample prepared with a measurement sample of 5 cm × 5 cm and measured with an electronic balance. The thickness of the transparent composite sheet can be obtained by preparing a measurement sample of 5 cm × 5 cm, measuring the thickness of four corners in the measurement sample with a micrometer, and taking the average of these. it can.

Moreover, in the transparent composite sheet of this embodiment, the air permeability of the glass fiber fabric is preferably 55 to 150 cm ³ / cm ² / sec, more preferably 60 to 140 cm ³ / cm ² / sec, It is preferably 65 to 130 cm ³ / cm ² / sec, particularly preferably 70 to 125 cm ³ / cm ² / sec, particularly preferably 75 to 110 cm ³ / cm ² / sec, particularly preferably 80 to a 100cm ³ / cm ² / sec, most preferably 85~95cm ³ / cm ² / sec. The porosity of the glass fiber fabric is, for example, 3.5 to 12.0%, preferably 4.0 to 11.0%, more preferably 4.5 to 10.0%. More preferably, it is 5.0 to 9.0%, particularly preferably 5.2 to 8.8%, particularly preferably 5.5 to 8.5%, and most preferably 6.0 to 8.0%.

  The air permeability of the glass fiber fabric is measured according to JIS R 3420 (Glass Fiber General Test Method). Here, as a measurement target of the air permeability of the glass fiber fabric, for example, the glass fiber fabric remaining after removing the resin by heating the transparent composite sheet at 600 ° C. for 24 hours can be used.

  When the average void width Wt (μm), the average weft width Wy (μm) of the warp, the weave density Dt (line / 25 mm), and the weave density Dy (line / 25 mm) of the weft are used as the porosity. , (25000 × 25000−25000 × Wt × Dt−25000 × Wy × Dy + Wt × Dt × Wy × Dy) / (25000 × 25000) × 100.

  In the transparent composite sheet of the present embodiment, the methacrylic silane as the silane coupling agent includes 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxy. Examples thereof include silane and 3-methacryloxypropyltriethoxysilane.

  Examples of the cationic silane as the silane coupling agent include N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride, N-2- (aminoethyl) -3- Aminopropylmethyldimethoxysilane hydrochloride, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane hydrochloride, 3-aminopropyltrimethoxysilane hydrochloride, 3-aminopropyltriethoxysilane hydrochloride, 3-tri Examples thereof include ethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine hydrochloride, N-phenyl-3-aminopropyltrimethoxysilane hydrochloride and the like.

  Here, the silane coupling agent can be identified by, for example, GC-MS (for example, GC-MSQP2010Ultra (trade name) manufactured by Shimadzu Corporation).

  In addition, as said silane coupling agent, it is more preferable to use the said methacryl silane from the point which the haze of the obtained transparent composite sheet becomes 10% or less, and is more excellent in transparency.

  Moreover, in the transparent composite sheet of this embodiment, the resin composition is a vinyl chloride-vinyl acetate copolymer resin, preferably 48.0 to 70.0% by mass with respect to the total mass of the resin composition. More preferably, it contains 50.0-65.0 mass%, More preferably, it is 52.0-60.0 mass%, Most preferably, it contains 53.0-57.0 mass%. In addition, the resin composition has a plasticizer of 30 to 39% by mass, a flame retardant of 0 to 10% by mass, and a refraction as a component other than the vinyl chloride-vinyl acetate copolymer resin with respect to the total mass of the resin composition. 0-10 mass% of rate regulators can be included. In addition, content (content ratio) of each component in the said resin composition is the light absorbency of the peak derived from each component using FT-IR (For example, Perkin Elmer Japan Co., Ltd. make, Spectrum 100 (brand name)). Can be calculated by comparing the absorbance of each peak. Here, as a measurement object for obtaining the content of each component in the resin composition, a transparent composite sheet is an organic solvent that dissolves the resin composition but does not dissolve a soft vinyl chloride resin film (for example, acetone, Obtained by leaching the resin composition in the transparent composite sheet into an organic solvent to obtain a resin composition solution, and then drying and volatilizing the organic solvent in the resin composition solution. A resin film can be used.

Examples of the plasticizer include phosphate ester plasticizers, phthalate ester plasticizers, and polyester plasticizers. Examples of the flame retardant include a phosphate ester flame retardant and a bromine flame retardant. Examples of the refractive index adjusting agent include bisphenol A type epoxy resins and bisphenol F type epoxy resins.
Is mentioned.

  Further, the transparent composite sheet of this embodiment may only be impregnated with the resin composition in the glass fiber fabric, but the upper and lower surfaces of the glass fiber fabric impregnated with the resin composition. A soft vinyl chloride resin film laminated on the substrate may be provided. One or two soft vinyl chloride resin films can be laminated on the upper and lower surfaces of the glass fiber fabric impregnated with the resin composition. From the viewpoint of production efficiency, one soft vinyl chloride resin film is laminated on the upper and lower surfaces. It is preferable to do. In order to obtain a transparent composite sheet having excellent transparency, the soft vinyl chloride resin film is preferably a transparent soft vinyl chloride resin film. Specifically, the total light transmittance of 90% or more and 5 It is preferable that it is a transparent soft vinyl chloride resin film provided with the haze of% or less. Further, in the transparent composite sheet of the present embodiment including the transparent soft vinyl chloride resin film, in order to make it difficult to perceive the presence of the sheet, and particularly to reduce the feeling of pressure given to the person by the presence of the sheet in a closed space, The transparent soft vinyl chloride resin film does not contain a dye or pigment, and is preferably a colorless and transparent transparent soft vinyl chloride resin film.

In this case, the mass per unit area of the one soft vinyl chloride resin film is, for example, 20 to 300 g / m ² , preferably 80 to 220 g / m ² , and more preferably 100 to 150 g / m ^2. It is. Moreover, the thickness of one said soft vinyl chloride resin film is 20-240 micrometers, for example, Preferably it is 60-150 micrometers, More preferably, it is 80-120 micrometers. The mass per unit area of the soft vinyl chloride resin film can be calculated from the mass of the measurement sample measured with an electronic balance by preparing a measurement sample of 5 cm × 5 cm. Moreover, the thickness of the said soft vinyl chloride resin film made the sample for a measurement of 5 cm x 5 cm, measured the thickness of four corners in a sample for measurement with a micrometer, and took these averages. Can be sought. The soft vinyl chloride resin film is peeled after scratching the soft vinyl chloride resin film, or when it is difficult to remove, the transparent composite sheet is dissolved in the resin composition but is soft. The resin composition can be separated from the transparent composite sheet by immersing it in an organic solvent that does not dissolve the vinyl chloride resin film (for example, acetone or methyl ethyl ketone) and eluting the resin composition into the organic solvent.

  As the soft vinyl chloride resin, for example, a resin containing 31 to 39% of a plasticizer can be used.

  Further, in the transparent composite sheet of the present embodiment, the difference in refractive index between the glass fiber fabric and the resin composition, the difference in refractive index between the glass fiber fabric and the soft vinyl chloride resin film, and the resin composition The difference in refractive index from the soft vinyl chloride resin film is less than 0.010, preferably less than 0.005, whereby excellent transparency can be obtained.

  Moreover, in the transparent composite sheet of this embodiment, the vinyl chloride-vinyl acetate copolymer resin is composed of 70 to 95% of a structural unit derived from a vinyl chloride monomer and 5 to 30% of a structural unit derived from a vinyl acetate monomer. It is preferable to become. More preferably, the vinyl chloride-vinyl acetate copolymer resin is composed of 75 to 93% of structural units derived from vinyl chloride monomer and 7 to 25% of structural units derived from vinyl acetate monomer. More preferably, it is composed of 80 to 92% of structural units and 8 to 20% of structural units derived from vinyl acetate monomer, and is composed of 85 to 91% of structural units derived from vinyl chloride monomer and vinyl acetate monomer. It is particularly preferably composed of 9 to 15%, and most preferably composed of 86 to 90% of structural units derived from vinyl chloride monomer and 10 to 14% of structural units derived from vinyl acetate monomer.

  Here, the vinyl chloride-vinyl acetate copolymer resin composed of 70 to 95% of a structural unit derived from a vinyl chloride monomer and 5 to 30% of a structural unit derived from a vinyl acetate monomer has a vinyl chloride monomer content of 70 to 95 mol. % And vinyl acetate monomer 5-30% is a resin that is a copolymer. Specifically, a resin composed of a structural unit A% derived from the vinyl chloride monomer and a structural unit (100-A)% derived from the vinyl acetate monomer (that is, the vinyl chloride monomer A mol%) , The vinyl acetate monomer (100-A) mol%) is vinyl chloride so that the number of moles of vinyl chloride monomer: number of moles of vinyl acetate monomer = A: (100-A). It is a resin obtained by copolymerizing a monomer and a vinyl acetate monomer.

The ratio of the number of moles of vinyl chloride monomer to the number of moles of vinyl acetate monomer can be determined by the following method, for example. First, FT-IR (for example, Spectrum, manufactured by PerkinElmer Japan Co., Ltd.) is used for at least two types of vinyl chloride-vinyl acetate copolymer resins in which the ratio between the number of moles of vinyl chloride monomer and the number of moles of vinyl acetate monomer is known. 100 (trade name)) at analyzed, 1744 cm ^-1 vicinity of absorbance (corresponding to C = O stretching vibration in the vinyl acetate monomer) and 1425cm ^-1 vicinity of absorbance (in _CH 2 Cl in the vinyl chloride monomer CH ₂ Corresponding to the symmetric bending vibration). Next, a calibration curve is prepared by the ratio of the number of moles of vinyl chloride monomer to the number of moles of vinyl acetate monomer and the ratio of these absorbances. Then, the resin to be determined the number of moles of moles of vinyl acetate monomer in the vinyl chloride monomer was analyzed by FT-IR, determining the ratio between the absorbance and 1425cm ^-1 vicinity absorbance near 1744 cm ^-1. Finally, the ratio between the number of moles of vinyl chloride monomer and the number of moles of vinyl acetate monomer can be determined from the absorbance ratio and calibration curve determined. Here, as a target to which FT-IR is applied, a transparent composite sheet is immersed in an organic solvent (for example, acetone, methyl ethyl ketone) that dissolves the resin composition but does not dissolve a soft vinyl chloride resin film. The resin composition obtained by eluting the resin composition in the sheet into an organic solvent to obtain a resin composition solution, and then drying and volatilizing the organic solvent in the resin composition solution can be used.

  The transparent composite sheet of this embodiment can be suitably used for flameproof curtains, smokeproof partitions, smokeproof hanging walls, smokeproof shutters, and the like. In particular, the transparent composite sheet of this embodiment is preferably used as a flameproof accordion curtain.

  The flameproof accordion curtain including the transparent composite sheet of the present embodiment is configured by attaching the transparent composite sheet of the present embodiment folded in a bellows shape to a framework that expands and contracts in a pantograph shape.

  Next, examples and comparative examples of the present invention are shown.

[Example 1]
In this example, a vinyl chloride-vinyl acetate copolymer resin having a ratio of a vinyl chloride monomer-derived structure to a vinyl acetate monomer-derived structure of 88:12 is 56.4% by mass, and a phosphate ester 38.0 is used as a plasticizer. A resin solution (manufactured by Kobayashi Co., Ltd.) prepared by adding an organic solvent to a resin composition consisting of 5.6% by mass of bisphenol A type epoxy resin as an additive and having a solid content of 33%. Glass fiber fabric was impregnated.

Glass fiber fabric is IPC spec 1080 type (E glass fiber yarn used, warp (weft) yarn filament diameter 7μm, warp (weft) yarn filament concentrating number 200, warp (weft) yarn mass 11.2tex, warp weave density) 60/25 mm, weft weaving density 46/25 mm, plain weave structure) so that the thickness is 50 μm, the air permeability is 86 cm ³ / cm ² / sec, and the porosity is 6.6%. What was surface-treated with 3-methacryloxypropyltrimethoxysilane (a kind of methacrylic silane) (manufactured by Nitto Boseki Co., Ltd.) was used.

The E _glass, SiO 2 52.0 to 56.0 _{wt%, B} 2 O 3 5.0 to 10.0 _{wt%, Al} 2 O 3 12.0 to 16.0 wt%, the CaO and MgO The composition includes 20 to 25% by mass in total and 0 to 1.0% by mass in total of Li ₂ O, K ₂ O, and Na ₂ O.

Next, the glass fiber woven fabric impregnated with the resin solution was dried at 120 ° C. for 10 minutes to evaporate the solvent, thereby obtaining a resin-impregnated glass fiber woven fabric. A transparent soft vinyl chloride resin film having a thickness of 100 μm, a mass per unit area of 126 g / m ² , a plasticizer content of 38% by mass, a total light transmittance of 92%, and a haze of 1% on the upper and lower surfaces of the resin-impregnated glass fiber fabric. (Made by Diamond Plus Film Co., Ltd.) Each one sheet is pasted and heat laminated at 160 ° C., 0.4 MPa, 0.5 m / min, and the resulting sheet is heated at 120 ° C. for 5 minutes to be transparent. A composite sheet was obtained.

The resulting transparent composite sheet is mass per unit area was 349 g / m ^2, of which the mass is 47 g / m ² per unit area of the glass fiber ^fabric, the mass per unit area of the resin composition is 50 g / The total mass of m ² and the soft vinyl chloride film per unit area was 252 g / m ² , and the content of the glass fiber fabric was 13% by mass with respect to the total mass of the transparent composite sheet. The thickness of the transparent composite sheet was 250 μm.

  Next, the air permeability of the glass fiber fabric, the refractive index of the glass fiber fabric, the refractive index of the resin composition, and the refractive index of the transparent soft vinyl chloride resin film were measured by the following methods. The results are shown in FIG.

[Measurement method of air permeability of glass fiber fabric]
The air permeability of the glass fiber fabric was measured in accordance with JIS R 3420 (Glass Fiber General Test Method) using a Fragile Permemeter (Toyo Seiki Seisakusho Co., Ltd.).

[Measurement method of refractive index of glass fiber fabric]
The refractive index of the glass fiber woven fabric was measured according to JIS K7142 (Plastics—Method of obtaining refractive index) B method. Specifically, first, the glass fiber fabric was pulverized to obtain glass fiber powder. In addition, when the compound adheres to the glass fiber fabric surface (including the case where the glass fiber fabric is embedded in the resin), the glass fiber fabric is heated at 625 ° C. for 30 minutes before pulverization, The resin was removed.

  Next, a predetermined amount of benzyl alcohol (nD: 1.539) and 1-bromonaphthalene (nD: 1.655) are mixed, and the refractive index of the liquid after mixing is determined by Abbe refractometer (manufactured by Atago Co., Ltd., DR- M2 (trade name)), and a plurality of immersion liquids were prepared so that the refractive index was in increments of 0.001. A glass fiber powder is placed on a slide glass, one of the immersion liquids is dropped onto the glass fiber powder, a cover glass is placed on the glass fiber powder, and a spectroscope (SPG-120S manufactured by Shimadzu Corporation, trade name) The glass fiber powder was observed with a microscope (manufactured by Shimadzu Corporation, AE31 (trade name)) using D line (589 nm) as a light source.

  Next, after focusing on the glass fiber powder, the microscope barrel is moved to separate the microscope objective lens from the glass fiber powder and remove the focus. Whether the refractive index of the glass fiber powder or the immersion liquid is higher in the direction in which the visible Becke line moves is determined, and the immersion liquid is appropriately changed.

  Finally, if the movement of the Becke line stops, the refractive index of the immersion liquid, or the average value of the two immersion liquids when the refractive index of the glass fiber powder falls between the two immersion liquids. The refractive index of the glass fiber fabric was used.

[Method of measuring refractive index of resin composition]
The refractive index of the resin composition is the same as that when the transparent composite sheet is manufactured, except that the glass fiber fabric is not included. A sheet made of the resin composition is manufactured under the same conditions, and JIS K7142 (Plastic- Determination of refractive index) The refractive index was determined by measuring the refractive index in accordance with Method A.

  The same method as that for measuring the refractive index of the glass fiber powder in the refractive index measurement method of the glass fiber fabric for the resin powder obtained by scraping the surface of the transparent composite sheet from which the resin film was removed. It is also possible to measure the refractive index of the resin composition by measuring the refractive index.

[Method for measuring refractive index of resin film]
The refractive index of the resin film was measured in accordance with JIS K7142 (Plastic—Method of obtaining refractive index) A method. For the measurement, an Abbe refractometer (manufactured by Atago Co., Ltd., DR-M2 (trade name)) was used. As the intermediate solution, 1-bromonaphthalene was used.

  In addition, about the resin powder obtained by shaving the part (surface part of a transparent composite sheet) equivalent to a resin film from a transparent composite sheet, the refractive index of glass fiber powder in the refractive index measurement method of the said glass fiber fabric is used. It is also possible to measure the refractive index of the resin film by measuring the refractive index in the same manner as the measurement.

  In this example, the refractive index measured by the measurement method was glass fiber fabric 1.554, resin composition 1.550, and transparent soft vinyl chloride resin film 1.554. The results are shown in FIG.

  About the transparent composite sheet obtained by the present Example, the total light transmittance and haze were measured with the following method. Moreover, about the transparent composite sheet obtained by the present Example, the impregnation property, the crease whitening resistance, the peel resistance, the burnout resistance, and the flameproofness were evaluated by the following methods. The results are shown in FIG.

[Measurement method of total light transmittance of transparent composite sheet]
The total light transmittance of the transparent composite sheet was measured in accordance with JIS K7361-1 (Plastic—How to determine the total light transmittance of a transparent material) using a haze meter NDH500 (manufactured by Nippon Denshoku Industries Co., Ltd.). did. For the measurement, a sample obtained by cutting a transparent composite sheet and molding it to 50 mm × 50 mm was used.

[Measurement method of haze of transparent composite sheet]
The haze of the transparent composite sheet was measured using a haze meter NDH500 (manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K7136 (how to determine the haze of a plastic-transparent material). For the measurement, a sample obtained by cutting a transparent composite sheet and molding it to 50 mm × 50 mm was used.

[Evaluation method of impregnation of transparent composite sheet]
The impregnation property of the transparent composite sheet was evaluated by observation of the appearance after the production of the transparent composite sheet. The case where there was no resin non-impregnated part (white streaks) in the glass fiber woven fabric part impregnated with the resin composition in the transparent composite sheet was marked with ◯, and the case where there was a resin non-impregnated part x.

[Evaluation Method for Bending Resistance of Transparent Composite Sheet]
The folding whitening resistance of the transparent composite sheet was evaluated by the presence or absence of whitening (a phenomenon in which the folded portion turns white) using a bending fatigue tester MIT-D2 (manufactured by Toyo Seiki Seisakusho Co., Ltd.). For the evaluation, a sample obtained by cutting a transparent composite sheet and molding it to 15 mm × 110 mm was used. Specifically, the sample was bent 50 times under the conditions of a load of 1.0 kgf, an angle of 135 °, and a speed of 90 cpm, and then the bent portion was observed to evaluate the presence or absence of whitening. The case where the bent part was not whitened was marked with ◯, and the case where the bent part was whitened was marked with x.

[Evaluation method of peel resistance of transparent composite sheet]
The peel resistance of the transparent composite sheet was evaluated by the degree of peeling of the resin film (transparent soft vinyl chloride resin film). For the evaluation, a sample obtained by cutting a transparent composite sheet and molding it to 25 mm × 250 mm was used. Specifically, when the resin film was peeled off from the sample with a scribing stick, it was evaluated whether or not the soft vinyl chloride film was peeled off and whether or not the resin film remained on the peeled surface. ◎ When the resin film cannot be peeled off with a scriber, ◯ when it can be peeled off with a scriber but part of the resin film remains on the peeled surface, it can be peeled off with a scriber The case where it did not remain on the peeled surface was marked with x.

[Measurement method of flame resistance of transparent composite sheet]
The flame resistance of the transparent composite sheet was evaluated using a cone calorimeter (manufactured by Toyo Seiki Seisakusho Co., Ltd.) according to ISO 5660-1 (exothermic test). For the evaluation, a sample molded into a size of 99 mm × 99 mm was used. Specifically, the evaluation was made based on the size of the pinhole after the exothermic test. The case where the pinhole was 0.5 mm or less was marked as ◯, and the case where the pinhole was larger than 0.5 mm was marked as x.

[Measurement method of flame resistance of transparent composite sheet]
The flame resistance of the transparent composite sheet conforms to JIS L 1091A-1 (Flameability test method for textile products-45 ° micro burner method) using a combustion tester FL-45 (manufactured by Suga Test Instruments Co., Ltd.). And evaluated. For the evaluation, a 25 cm × 35 cm sample was used. When the afterflame time is 3 seconds or less, the residual time is 5 seconds or less, and the carbonized area is 0 to less than 15 cm2, the afterflame time is 3 seconds or less, the residual time is 5 seconds or less, and the carbonized area is 15 to 25 cm2. In the case of less than ◯, in the other case, it was set as x.

[Example 2]
In this example, instead of the 3-methacryloxypropyltrimethoxysilane as a silane coupling agent, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride (cationic silane A transparent composite sheet was obtained in the same manner as in Example 1 except that 1 type) was used.

  About the transparent composite sheet obtained in this example, exactly the same as in Example 1, the air permeability of the glass fiber fabric, the refractive index of the glass fiber fabric, the refractive index of the resin composition, the refraction of the transparent soft vinyl chloride resin film Rate, total light transmittance, and haze were measured. In addition, the transparent composite sheet obtained in this example was evaluated in the same manner as in Example 1 in terms of impregnation, whitening resistance, peel resistance, flame resistance, and flame resistance. The results are shown in FIG.

Example 3
In this example, instead of the vinyl chloride-vinyl acetate copolymer resin in which the ratio of the structure derived from the vinyl chloride monomer and the structure derived from the vinyl acetate monomer is 88:12, the structure derived from the vinyl chloride monomer and the structure derived from the vinyl acetate monomer are used. A transparent composite sheet was obtained in the same manner as in Example 1 except that a vinyl chloride-vinyl acetate copolymer resin having a structure ratio of 60:40 was used.

Mass per unit area of the obtained transparent composite sheet is a 351 g / m ^2, mass 47 g / m ² of them per unit area of the glass fiber ^fabric, the mass per unit area of the resin composition is 52 g / m ^2. The mass per unit area of the soft vinyl chloride film was 252 g / m ² in total, and the content of the glass fiber fabric was 13% by mass with respect to the total mass of the transparent composite sheet. The thickness of the transparent composite sheet was 253 μm.

  About the transparent composite sheet obtained in this example, exactly the same as in Example 1, the air permeability of the glass fiber fabric, the refractive index of the glass fiber fabric, the refractive index of the resin composition, the refraction of the transparent soft vinyl chloride resin film Rate, total light transmittance, and haze were measured. In addition, the transparent composite sheet obtained in this example was evaluated in the same manner as in Example 1 in terms of impregnation, whitening resistance, peel resistance, flame resistance, and flame resistance. The results are shown in FIG.

[Comparative Example 1]
In this comparative example, as a glass fiber fabric, IPC specification 1078 type (E glass fiber yarn used, warp (weft) filament diameter 7 μm, warp (weft) filament filament number 200, warp (weft) yarn mass 11. 2 tex, warp weave density 53 / 25mm, weft weave density 53 / 25mm, plain weave structure), thickness 42μm, air permeability 10cm ³ / cm ² / sec, porosity 0.4% Thus, a transparent composite sheet was obtained in exactly the same manner as in Example 1 except that a surface treated with 3-methacryloxypropyltrimethoxysilane (manufactured by Nitto Boseki Co., Ltd.) was used. The mass per unit area of the obtained transparent composite sheet is 350 g / m ² , of which the mass per unit area of the glass fiber fabric is 48 g / m ² , and the mass per unit area of the resin composition is 50 g / m 2. ^2. The mass per unit area of the soft vinyl chloride film was 252 g / m ² in total, and the content of the glass fiber fabric was 14% by mass with respect to the total mass of the transparent composite sheet. The thickness of the transparent composite sheet was 242 μm.

  Next, with respect to the transparent composite sheet obtained in this comparative example, exactly the same as in Example 1, the air permeability of the glass fiber fabric, the refractive index of the glass fiber fabric, the refractive index of the resin composition, the transparent soft vinyl chloride resin The refractive index, total light transmittance, and haze of the film were measured. In addition, the transparent composite sheet obtained in this Comparative Example was evaluated in the same manner as in Example 1 in terms of impregnation property, crease whitening resistance, peel resistance, burnout resistance, and flame resistance. The results are shown in FIG.

[Comparative Example 2]
In this comparative example, as the fiberglass fabric, the IPC spec 1080 type is not opened, the thickness is 55 μm, the air permeability is 220 cm ³ / cm ² / sec, and the porosity is 13.0%. -A transparent composite sheet was obtained in exactly the same manner as in Example 1 except that a surface treated with methacryloxypropyltrimethoxysilane (manufactured by Nitto Boseki Co., Ltd.) was used.

The resulting transparent composite sheet is mass per unit area was 349 g / m ^2, of which the mass is 47 g / m ² per unit area of the glass fiber ^fabric, the mass per unit area of the resin composition is 50 g / The total mass of m ² and the soft vinyl chloride film per unit area was 252 g / m ² , and the content of the glass fiber fabric was 13% by mass with respect to the total mass of the transparent composite sheet. The thickness of the transparent composite sheet was 255 μm.

  Next, with respect to the transparent composite sheet obtained in this comparative example, exactly the same as in Example 1, the air permeability of the glass fiber fabric, the refractive index of the glass fiber fabric, the refractive index of the resin composition, the transparent soft vinyl chloride resin The refractive index, total light transmittance, and haze of the film were measured. In addition, the transparent composite sheet obtained in this Comparative Example was evaluated in the same manner as in Example 1 in terms of impregnation property, crease whitening resistance, peel resistance, burnout resistance, and flame resistance. The results are shown in FIG.

[Comparative Example 3]
In this comparative example, the same silane coupling agent as in Example 1 was used except that 3-aminopropyltrimethoxysilane (a kind of aminosilane) was used instead of 3-methacryloxypropyltrimethoxysilane. A composite sheet was obtained.

  Next, with respect to the transparent composite sheet obtained in this comparative example, exactly the same as in Example 1, the air permeability of the glass fiber fabric, the refractive index of the glass fiber fabric, the refractive index of the resin composition, the transparent soft vinyl chloride resin The refractive index, total light transmittance, and haze of the film were measured. In addition, the transparent composite sheet obtained in this Comparative Example was evaluated in the same manner as in Example 1 in terms of impregnation property, crease whitening resistance, peel resistance, burnout resistance, and flame resistance. The results are shown in FIG.

[Comparative Example 4]
In this comparative example, the same as Example 1 except that 3-glycidoxypropyltrimethoxysilane (a kind of epoxysilane) was used as the silane coupling agent instead of 3-methacryloxypropyltrimethoxysilane. Thus, a transparent composite sheet was obtained.

  Next, with respect to the transparent composite sheet obtained in this comparative example, exactly the same as in Example 1, the air permeability of the glass fiber fabric, the refractive index of the glass fiber fabric, the refractive index of the resin composition, the transparent soft vinyl chloride resin The refractive index, total light transmittance, and haze of the film were measured. In addition, the transparent composite sheet obtained in this Comparative Example was evaluated in the same manner as in Example 1 in terms of impregnation property, crease whitening resistance, peel resistance, burnout resistance, and flame resistance. The results are shown in FIG.

[Comparative Example 5]
In this comparative example, as a resin composition, a vinyl chloride vinyl acetate copolymer resin having a ratio of a structure derived from a vinyl chloride monomer to a structure derived from a vinyl acetate monomer of 88:12 is 40% by mass, and a phosphate ester 55. A transparent composite sheet was obtained in the same manner as in Example 1 except that a resin composition comprising 4% by mass and 5.6% by mass of bisphenol A type epoxy resin as an additive was used.

The mass per unit area of the obtained transparent composite sheet was 340 g / m ² , of which the mass per unit area of the glass fiber fabric was 47 g / m ² , and the mass per unit area of the resin composition was 41 g / m 2. ^2. The mass per unit area of the soft vinyl chloride film was 252 g / m ² in total, and the content of the glass fiber fabric was 14% by mass with respect to the total mass of the transparent composite sheet. The thickness of the transparent composite sheet was 246 μm.

  Next, with respect to the transparent composite sheet obtained in this comparative example, exactly the same as in Example 1, the air permeability of the glass fiber fabric, the refractive index of the glass fiber fabric, the refractive index of the resin composition, the transparent soft vinyl chloride resin The refractive index, total light transmittance, and haze of the film were measured. In addition, the transparent composite sheet obtained in this Comparative Example was evaluated in the same manner as in Example 1 in terms of impregnation property, crease whitening resistance, peel resistance, burnout resistance, and flame resistance. The results are shown in FIG.

[Comparative Example 6]
In this comparative example, as a resin composition, a vinyl chloride-vinyl acetate copolymer resin having a ratio of a structure derived from a vinyl chloride monomer to a structure derived from a vinyl acetate monomer of 88:12 is 80% by mass, and a phosphate ester is used as a plasticizer. A transparent composite sheet was obtained in exactly the same manner as in Example 1 except that a resin composition comprising 14.4% by mass and 5.6% by mass of bisphenol A type epoxy resin as an additive was used.

Mass per unit area of the obtained transparent composite sheet is a 365 g / m ^2, mass 47 g / m ² of them per unit area of the glass fiber ^fabric, the mass per unit area of the resin composition is 66 g / m ^2. The mass per unit area of the soft vinyl chloride film was 252 g / m ² in total, and the content of the glass fiber fabric was 13% by mass with respect to the total mass of the transparent composite sheet. The thickness of the transparent composite sheet was 261 μm.

  Next, with respect to the transparent composite sheet obtained in this comparative example, exactly the same as in Example 1, the air permeability of the glass fiber fabric, the refractive index of the glass fiber fabric, the refractive index of the resin composition, the transparent soft vinyl chloride resin The refractive index, total light transmittance, and haze of the film were measured. In addition, the transparent composite sheet obtained in this Comparative Example was evaluated in the same manner as in Example 1 in terms of impregnation property, crease whitening resistance, peel resistance, burnout resistance, and flame resistance. The results are shown in FIG.

[Comparative Example 7]
In this comparative example, instead of the vinyl chloride-vinyl acetate copolymer resin in which the ratio of the structure derived from the vinyl chloride monomer and the structure derived from the vinyl acetate monomer is 88:12 as the resin composition, A transparent composite sheet was obtained in the same manner as in Example 1 except that a vinyl chloride-vinyl acetate copolymer resin (polyvinyl chloride resin) having a structure ratio derived from the vinyl acetate monomer of 100: 0 was used.

Mass per unit area of the obtained transparent composite sheet is a 366 g / m ^2, mass 47 g / m ² of them per unit area of the glass fiber ^fabric, the mass per unit area of the resin composition is 67 g / m ^2. The mass per unit area of the soft vinyl chloride film was 252 g / m ² in total, and the content of the glass fiber fabric was 13% by mass with respect to the total mass of the transparent composite sheet. The thickness of the transparent composite sheet was 262 μm.

  Next, with respect to the transparent composite sheet obtained in this comparative example, exactly the same as in Example 1, the air permeability of the glass fiber fabric, the refractive index of the glass fiber fabric, the refractive index of the resin composition, the transparent soft vinyl chloride resin The refractive index, total light transmittance, and haze of the film were measured. In addition, the transparent composite sheet obtained in this Comparative Example was evaluated in the same manner as in Example 1 in terms of impregnation property, crease whitening resistance, peel resistance, burnout resistance, and flame resistance. The results are shown in FIG.

1, according to the transparent composite sheets of Examples 1 to 3 according to the present invention, the glass fiber fabric has an air permeability of 86 cm ³ / cm ² / sec, the glass fiber fabric has a refractive index of 1.554, and a resin composition. Has a refractive index of 1.550 (Examples 1 and 2) or 1.553 (Example 3), a transparent soft vinyl chloride resin film has a refractive index of 1.554, and vinyl chloride-vinyl acetate with respect to the total mass of the resin composition The content of the copolymer resin is 56.4% by mass, the total light transmittance of the transparent composite sheet is 90 to 91%, and the haze is 7 to 12%, providing excellent transparency, impregnation and folding resistance. It is clear that they are all excellent in whitening, peel resistance, burnout resistance and flameproofing.

On the other hand, the transparent composite sheet of Comparative Example 1 in which the air permeability of the glass fiber fabric is 10 cm ³ / cm ² / sec is not obtained from FIGS. In the transparent composite sheet of Comparative Example 2 having a degree of 220 cm ³ / cm ² / second, peel resistance and burn-out resistance cannot be obtained.

  Moreover, in the transparent composite sheet of Comparative Example 3 using aminosilane as the silane coupling agent, impregnation and crease whitening resistance cannot be obtained. In the transparent composite sheet of Comparative Example 4 using epoxy silane as the silane coupling agent, impregnation is performed. Sex cannot be obtained.

  Moreover, in the transparent composite sheet of Comparative Example 5 using a resin composition having a vinyl chloride-vinyl acetate copolymer resin content of 40% by mass with respect to the total mass of the resin composition, no peel resistance was obtained, and the resin composition In the transparent composite sheet of Comparative Example 6 using a resin composition having a vinyl chloride-vinyl acetate copolymer resin content of 80% by mass with respect to the total mass of the product, impregnation, fold whitening resistance, and flame resistance are obtained. Absent.

  Furthermore, in the resin composition, in the transparent composite sheet of Comparative Example 7 in which a polyvinyl chloride resin is used instead of the vinyl chloride-vinyl acetate copolymer resin, impregnation property, folding whitening resistance, and peel resistance cannot be obtained.

  Unsigned

Claims (5)

A transparent composite sheet comprising a glass fiber fabric and a resin composition impregnated in the glass fiber fabric,
Glass fibers constituting the glass fiber _fabric, SiO 2 52.0-56.0 _{wt%, B} 2 O 3 _{5.0~10.0 wt%, Al} 2 O 3 _12.0~16.0 wt% And a composition containing 20 to 25% by mass of CaO and MgO in total and 0 to 1.0% by mass of Li ₂ O, K ₂ O and Na ₂ O in total,
The glass fiber fabric has an air permeability of 50 to 200 cm ³ / cm ² / sec,
The glass fiber fabric has methacryl silane or cationic silane attached as a silane coupling agent on the surface,
The resin composition contains 45.0 to 75.0% by mass of a vinyl chloride-vinyl acetate copolymer resin based on the total mass of the resin composition,
The vinyl chloride-vinyl acetate copolymer resin is composed of 60 to 95% of structural units derived from vinyl chloride monomer and 5 to 40% of structural units derived from vinyl acetate monomer.
A transparent composite sheet having a total light transmittance of 85% or more and a haze of 20% or less.   2. The transparent composite sheet according to claim 1, further comprising a soft vinyl chloride resin film laminated on an upper surface and a lower surface of the glass fiber fabric impregnated with the resin composition.   The transparent composite sheet according to claim 2, wherein the refractive index difference between the glass fiber fabric and the resin composition, the refractive index difference between the glass fiber fabric and the soft vinyl chloride resin film, and the resin composition and the A transparent composite sheet, wherein the difference in refractive index from the soft vinyl chloride resin film is less than 0.010.   4. The transparent composite sheet according to claim 1, wherein the vinyl chloride-vinyl acetate copolymer resin is derived from 70 to 95% of a structural unit derived from a vinyl chloride monomer and a vinyl acetate monomer. A transparent composite sheet comprising 5 to 30% of structural units.   A flameproof accordion curtain comprising the transparent composite sheet according to any one of claims 1 to 4.