JP7105047B2 - Transparent noncombustible sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transparent noncombustible sheet using a glass fiber fabric and a thermoplastic resin, and more particularly to a transparent noncombustible sheet that suppresses the occurrence of whitening flaws due to sheet bending and folding and excels in maintaining transparency for a long period of time.

A noncombustible sheet is a noncombustible material specified by the Building Standards Law and the Building Standards Law Construction Ordinance, and in a heat buildup test, the total calorific value for 20 minutes after the start of heating is 8 MJ / m ² or less, and It is a requirement that the maximum heat release rate in 20 minutes from the start of heating does not exceed 200 kW/m ² and does not continue for 10 seconds or more, and that there are no through holes after combustion.

As such a noncombustible sheet, a glass fiber material or a composite sheet of glass fiber fabric and resin is known, and can be used as a building material.
For example, smoke-proof hanging walls that are installed on the ceiling of a building to prevent the movement and diffusion of smoke in the event of a fire, partition curtains that separate work areas in factories, and membrane ceilings that transmit the luminous intensity of the light source into the space as it is. It is used as a lighting membrane cover, and the demand for materials with high light transmission is increasing.

Thermosetting resins and vinyl chloride resins are mainly used as the resin to be combined with the glass fiber fabric.
For example, Patent Document 1 discloses a transparent nonflammable sheet comprising a glass fiber fabric and a cured resin layer such as a vinyl ester resin, and Patent Document 2 discloses a glass fiber base material impregnated with a soft vinyl chloride resin composition. A transparent composite sheet consisting of

When using a thermosetting resin as in Patent Document 1, the uncured state has a low viscosity, so it is easy to impregnate the glass fiber fabric, and the difference in refractive index between the glass fiber and the curable resin is 0.02 or less. By setting the Abbe number difference to 30 or less, a nonflammable sheet having excellent transparency can be obtained. However, the apparatus and process for forming the cured resin layer are relatively complicated, and the cost is high.
In addition, when the incombustible sheet is bent or folded, it is often observed that whitening damage occurs inside the sheet. This whitening damage is a state in which gaps are generated due to minute peeling between the interface between the thermosetting resin and the glass fiber fabric or between the fibers of the glass fiber fabric, and the gaps are not restored and refraction diffuse reflection occurs. , are visible as whitened scratches. In particular, since thermosetting resins are difficult to stretch, they cannot follow glass fiber fabrics and tend to cause whitening flaws. Therefore, a nonflammable sheet using a thermosetting resin is not very suitable for applications that require flexibility.
In addition, depending on the application, such a nonflammable sheet requires a large area, and generally, the width of the sheet is joined by sewing or heat welding, but it is easy with thermosetting resin. There is also the problem that the width of the sheet cannot be joined by heat welding.

Further, Patent Document 2 discloses adjusting the refractive index by adding a large amount of an aromatic phosphate ester compound, which is a type of plasticizer, to vinyl chloride resin as a refractive index adjuster. This makes it possible to reduce the difference in refractive index between the vinyl chloride resin and the glass fiber, thereby ensuring transparency.
However, in such a sheet containing a plasticizer in a resin, the plasticizer migrates (bleeds out) to the surface over time, making the surface more sticky and attracting dust and the like, making it easily soiled and difficult to handle. was difficult. Moreover, in a sheet obtained by impregnating and applying the soft vinyl chloride resin to a base material made of glass fiber, the adhesion between the glass fiber and the soft vinyl chloride resin is insufficient, and the sheet peels off. It was easy to cause whitening scratches on the surface.

Therefore, in Patent Document 3, an adhesive-impregnated glass cloth in which an adhesive component containing a non-aromatic triisocyanate compound and a binder resin is impregnated and coated on a glass cloth base material, and a soft vinyl chloride resin transparent layer is provided on both sides thereof. A transparent noncombustible sheet has been proposed.
The glass cloth base material is surface-treated with a silane coupling agent, and the reaction between the silane coupling agent and the triisocyanate compound of the adhesive component causes the inside of the sheet to bend or fold. It is disclosed that a sheet is obtained which does not readily develop whitening defects. In addition, by providing a soft vinyl chloride resin transparent layer on both sides, it is possible to connect the width of the sheet because it has excellent heat-welding property.

However, although the soft vinyl chloride resin transparent layer contains an aromatic phosphate ester compound as a plasticizer, the phosphate ester compound and the binder resin degrade from the adhesive-impregnated glass cloth to the soft vinyl chloride resin transparent layer over time. It migrates to the layer and causes bleeding. As a result, there is a problem that the difference in refractive index between the glass cloth and the adhesive component increases and the transparency decreases with time.

In order to suppress such bleeding out of the plasticizer from the impregnated layer, Patent Document 4 discloses that the plasticizer contained in the vinyl chloride resin composition to be impregnated into the glass fiber fabric has a molecular weight of greater than 420. Although countermeasures such as the use of such materials have been considered, they have not completely improved the problem of transparency deterioration over time.

JP-A-2005-319746 JP 2010-052370 A JP 2014-076563 A JP 2015-077756 A

Therefore, the present invention provides a sheet made of a glass fiber fabric composited with a thermoplastic resin, which has excellent flexibility without causing whitening damage even if the sheet is repeatedly folded or folded, and To provide a transparent noncombustible sheet capable of maintaining transparency for a long period of time.

As a result of studies to solve the above problems, the inventors of the present invention have found that when a styrene-based thermoplastic elastomer is used as a thermoplastic resin to be impregnated into a glass fiber fabric, the refractive index is and flexibility can be adjusted, and the impregnation with the glass fiber fabric is good, and even if the sheet composited with the glass fiber fabric is repeatedly folded and folded, whitening damage will not occur inside the sheet. This finding led to the invention of the present application.

That is, the present invention comprises an intermediate layer in which a glass fiber fabric is impregnated with a styrene-based thermoplastic elastomer, and a vinyl chloride resin film layer laminated on both sides of the intermediate layer, and the plasticity in the vinyl chloride resin film layer is The addition amount of the agent is 15 to 40% by weight with respect to 100% by weight of the film, and the styrenic thermoplastic elastomer is hydrogenated and has a glass transition temperature of -20°C to 20°C. It is characterized by

In the present invention, since a styrene-based thermoplastic elastomer is used, it is possible to adjust the refractive index and flexibility without including a plasticizer in the resin impregnated into the glass fiber fabric, and the transparency can be maintained for a long time. can be maintained. Furthermore, since the styrene-based thermoplastic elastomer has excellent impregnating properties into the glass fiber fabric and adhesion properties with the vinyl chloride resin film layer, even if the sheet is repeatedly folded and folded, whitening damage will not occur inside the sheet. It is possible to obtain a transparent noncombustible sheet that does not have a flame, has excellent flexibility, and can maintain transparency for a long period of time.

Moreover, it is preferable that the refractive index difference between the glass fiber and the styrene-based thermoplastic elastomer is 0.03 or less. If the refractive index difference is 0.03 or less, the glass fiber fabric becomes inconspicuous and a highly transparent transparent noncombustible sheet can be obtained.

Further, in the present invention, the sheet having excellent transparency preferably has a total light transmittance of 80% or more and a haze of 30% or less.

Further, the styrene-based thermoplastic elastomer is a hydrogenated styrene-based thermoplastic elastomer, and the SP value of the hydrogenated butadiene portion is 17.5 (J/cm ³ ) ^1/2 or more. do.

If the SP value is within the range, the impregnation property into the glass fiber fabric is improved, so that the transparency is also enhanced, and the occurrence of whitening damage due to bending or folding can be further suppressed. In addition, since the adhesiveness between the vinyl chloride resin film layer and the intermediate layer is improved, there is no peeling and the flexibility is not impaired.

The present invention is a transparent noncombustible sheet comprising an intermediate layer formed by impregnating a glass fiber fabric with a styrene thermoplastic elastomer, and a vinyl chloride resin film layer laminated on both sides of the intermediate layer, wherein the styrene thermoplastic elastomer By using, it is possible to adjust the refractive index and flexibility without adding a plasticizer to the resin impregnated into the glass fiber fabric, and the transparency can be maintained for a long period of time. Furthermore, since the styrene-based thermoplastic elastomer has excellent impregnating properties into the glass fiber fabric and adhesion properties with the vinyl chloride resin film layer, the transparent noncombustible sheet of the present invention can be whitened inside the sheet even if it is repeatedly folded and folded. It is flexible and does not scratch.

The present invention is a transparent noncombustible sheet comprising an intermediate layer formed by impregnating a glass fiber fabric with a thermoplastic resin, and vinyl chloride resin film layers laminated on both sides of the intermediate layer.

The intermediate layer of the present invention will be described.
The intermediate layer is a glass fiber fabric impregnated with a thermoplastic resin, and in order to impart transparency, it is necessary to use a resin having a small difference in refractive index from the glass fiber of the glass fiber fabric. Therefore, in the present invention, a styrene-based thermoplastic elastomer is used as a resin whose refractive index can be easily adjusted.

Examples of styrene-based thermoplastic elastomers include block copolymers of styrene-based monomers and butadiene (SBS), block copolymers of styrene-based monomers and isoprene (SIS), and styrene- Ethylene-butylene-styrene-based block copolymer (SEBS), styrene-ethylene-propylene-styrene-based block copolymer (SEPS) in which the double bond portion of SIS is hydrogenated, etc. can be used, and hydrogenated styrene-based It is preferable to use a thermoplastic elastomer (hereinafter referred to as a hydrogenated styrenic thermoplastic elastomer). Further, the hydrogenation rate is preferably 90% or more, more preferably complete hydrogenation.

Examples of the styrene-based monomer include styrene, α-methylstyrene, p-methylstyrene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene and the like. Styrene or α-methylstyrene is preferred from the aspect. These styrenic monomers may be used alone or in combination of two or more.
On the other hand, examples of butadiene include 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-butadiene (isoprene) and the like. 3-butadiene is preferred. These butadiene-based monomers may be used alone or in combination of two or more.

Styrene-based thermoplastic elastomers have a styrene block region (hard segment) that imparts strength and an ethylene-butylene region (soft segment) that imparts rubber elasticity. characteristics. For example, it is excellent in heat resistance, weather resistance, transparency, and compatibility with other resins, and can provide flexibility equivalent to that of soft vinyl chloride resin. In particular, a hydrogenated styrenic thermoplastic elastomer in which the double bond portion is hydrogenated has excellent weather resistance.

Moreover, unlike vinyl chloride resins, the refractive index of styrene-based thermoplastic elastomers can be adjusted by adjusting the composition of hard segments and soft segments without adding additives such as plasticizers. Therefore, when impregnated into a glass fiber fabric, the difference in refractive index from the glass fiber increases due to the bleeding out of the plasticizer from the intermediate layer, and the transparency does not decrease over time, and the transparency can be maintained for a long time. .
In the present invention, one whose refractive index is adjusted to the range of 1.53 to 1.59 can be used. Within this range, since the average refractive index of general-purpose glass fiber (E glass) is about 1.56, the difference in refractive index can be minimized.
The refractive index difference between the styrene-based thermoplastic elastomer and the glass fiber is preferably 0.03 or less, more preferably 0.02 or less. If the refractive index difference is 0.03 or less, the glass fiber fabric becomes inconspicuous and a noncombustible sheet with high transparency can be obtained.

The refractive index is determined according to JIS K 7142, and materials with similar refractive indices are excellent in transparency.

In addition, the flexibility of the styrene-based thermoplastic elastomer can be adjusted by adjusting the composition of the hard segment and the soft segment. It is.
In addition, since the styrene-based thermoplastic elastomer has excellent impregnation properties into the glass fiber fabric, even if the intermediate layer is repeatedly folded and folded, fine particles are formed at the interface between the styrene-based thermoplastic elastomer and the glass fiber fabric and between the glass fibers. It is possible to suppress the occurrence of whitening flaws inside the sheet without creating a gap due to excessive peeling.

In particular, in the hydrogenated styrenic thermoplastic elastomer, it is preferable that the hydrogenated butadiene portion has an SP value of 17.5 (J/cm ³ ) ^1/2 or more. Within this range, excellent compatibility and wettability with highly polar resins and inorganic materials can be obtained.
When the hydrogenated styrene thermoplastic elastomer is used in the intermediate layer, the impregnation of the glass fiber fabric is improved, so the transparency is increased (the haze value is lowered), and the occurrence of whitening damage due to bending and folding is further suppressed. can. It also has excellent adhesiveness to a vinyl chloride resin film layer, which will be described later.

Here, the solubility parameter (SP value, Solubility Parameter) is used to evaluate the solubility, adhesion, or wettability to other substances. The SP value is calculated from the formula: (molar cohesive energy (J/mol)/molar volume (10 ⁻⁶ m ³ /mol)) ^1/2 .

In the present invention, the glass transition temperature (Tg) of the styrene-based thermoplastic elastomer is preferably in the range of -55 to 30°C, more preferably -20 to 20°C. In addition, when it is in this range, the adhesiveness to the vinyl chloride resin film is enhanced, and the sheet has a higher flexibility.

In the present invention, as the glass fiber fabric to be impregnated with the styrene-based thermoplastic elastomer, a fabric such as a woven fabric, a knitted fabric, or a nonwoven fabric composed of warps and wefts made of glass fibers can be used.

As the glass fibers constituting the glass fiber fabric, known glass fibers can be used, for example, general-purpose alkali-free glass fibers (E glass), acid-resistant alkali-containing glass fibers (C glass), alkali-resistant glass fibers. (AR glass), high strength and high elastic modulus glass fiber (S glass, T glass), and the like.
Among them, E-glass is preferable from the viewpoint of versatility and refractive index difference from that of the styrene-based thermoplastic elastomer, and S-glass and T-glass are preferable from the viewpoint of flexibility.

Further, the glass fiber constituting the glass fiber fabric preferably has a filament diameter in the range of 4 to 7 μm. By setting the diameter of the glass fiber within the above range, the strength of the fiber fabric is good, and the impregnation of the styrene-based thermoplastic elastomer between the fibers is good.

Further, the glass fiber fabric is preferably surface-treated with a silane coupling agent or the like on the glass fibers constituting the glass fiber fabric. Specific examples include vinylsilane, phenylsilane, epoxysilane, acrylsilane, aromatic aminosilane, and aliphatic aminosilane, with aromatic aminosilane being preferred.
By subjecting the glass fiber to the surface treatment, the impregnation property with the styrene-based thermoplastic elastomer is enhanced, and good transparency can be maintained. It is possible to suppress the occurrence of whitening damage inside the sheet due to peeling of the sheet.

Further, the glass fiber fabric preferably has a basis weight of 20 to 60 g/m ² .
If the basis weight of the glass fiber fabric is less than 20 g/m ² , impregnation with the styrene-based thermoplastic elastomer can be carried out satisfactorily, but the strength of the sheet may be low and deformation may occur during processing. On the other hand, if the basis weight exceeds 60 g/m ² , impregnation of the resin between the glass fibers becomes difficult, and the transparency of the transparent noncombustible sheet may decrease.

Further, the glass fiber fabric preferably has a gap of 0.5 mm or less between adjacent warp fiber bundles and between adjacent weft fiber bundles constituting the glass fiber cloth. If there is a gap larger than the above range, it may be difficult to obtain noncombustibility.
In this case, in terms of weave density, the warp density and weft density are preferably 60/2.54 cm or more, the gap between the fiber bundles can be 0.5 mm or less, and excellent noncombustibility can be maintained.

In the intermediate layer of the present invention, the amount of the styrene-based thermoplastic elastomer attached to the glass fiber fabric is not particularly specified, but is preferably 10 to 90 g/m ² in a dry state, more preferably 30 to 90 g/m ² . preferable. If the coating amount is too small, it is difficult to obtain good transparency, and if the coating amount is too large, nonflammability cannot be obtained.

In the present invention, the impregnability is evaluated by using a digital microscope and using a value calculated by calculating the area ratio of the portion where the glass fiber is visible without being impregnated with the resin by area calculation of the luminance extraction region. The area ratio is preferably less than 20%.
In areas where the glass fiber is visible without being impregnated with resin, the white color of the glass fiber is visible, creating a difference in brightness from the area where the resin is impregnated (transparent). can be asked for.

The intermediate layer may contain other additives, if necessary, except those having bleeding properties. Examples thereof include coloring pigments, inorganic fillers, flame retardants, lubricants, heat stabilizers, antioxidants, ultraviolet absorbers, light diffusing agents, and other resins.

Next, the vinyl chloride resin film layer of the present invention will be explained.
In the present invention, vinyl chloride resin film layers are laminated on both sides of the intermediate layer. By providing the vinyl chloride resin film layer, the non-combustibility is improved, and the width of the sheet can be joined by heat welding.
Moreover, in order to obtain a transparent nonflammable sheet, the vinyl chloride resin film layer is preferably transparent. Specifically, the total light transmittance is 90% or more and the haze value is 5% or less.

In the present invention, the vinyl chloride resin is not particularly limited, but for example, a soft vinyl chloride resin containing a plasticizer can be used.
The amount of the plasticizer to be added is desirably 15 to 40% by weight based on the weight of the film. Even if the vinyl chloride resin film layer contains a plasticizer, the transparency of the nonflammable sheet does not deteriorate, and this has not been confirmed over time.
Furthermore, additives such as flame retardants, ultraviolet absorbers, fillers, antistatic agents, and colorants may be contained within a range that does not impair the effects of the present invention.

The surface of the vinyl chloride resin film layer may be subjected to surface treatment for purposes such as antiblocking and antistatic.
In addition, although the vinyl chloride resin film and the styrene thermoplastic elastomer impregnated in the intermediate layer have excellent adhesiveness, in order to further improve the adhesiveness, the surface of the vinyl chloride resin film that comes into contact with the intermediate layer is also surface-treated. may be applied.

The thickness of the vinyl chloride resin film layer is not particularly limited, but each layer preferably has a thickness of 0.05 to 0.2 mm, more preferably 0.08 to 0.15 mm. If it is thicker than 0.2 mm, the noncombustibility is lowered. If the thickness is less than 0.05 mm, the unevenness of the glass fiber fabric affects the surface of the vinyl chloride film, resulting in a decrease in visibility.

INDUSTRIAL APPLICABILITY The present invention is a transparent noncombustible sheet which is formed by laminating vinyl chloride resin film layers on both sides of an intermediate layer, does not cause whitening damage inside the sheet even after repeated bending and folding, and has excellent flexibility.

In the present invention, transparency is evaluated by total light transmittance and haze value measured using a haze meter.
The nonflammable sheet of the present invention has a total light transmittance of 80% or more, preferably 90% or more. With a transmittance of 80% or more, it has high transparency. For example, when used as a curtain for disaster prevention, the opposite side of the sheet can be seen. It does not excessively reduce the brightness of illumination or the like.
Also, the haze value is preferably 30% or less, more preferably 20% or less. When the haze value is within the above range, visibility on the opposite side of the obtained sheet is improved.
Furthermore, in the present invention, when the haze value after the accelerated test at 40° C. for 8 weeks was measured, the rate of change from before the accelerated test was less than 10%, and no change in transparency over time was observed.

In addition, the present invention performs a heat generation test with a cone calorimeter tester based on Article 2, Item 9 of the Building Standards Law and Article 108-2 of the Enforcement Order of the Building Standards Law, and the maximum heat generation rate after the start of heating is 10 seconds. The above requirements must not exceed 200 kW/m ² continuously and the total calorific value must be 8 MJ/m ² or less, and have nonflammability.

In the present invention, the flexibility is evaluated by using an MIT folding endurance tester and counting the number of times until whitening flaws occur inside the sheet when repeatedly folded.
The sheet of the present invention showed high flexibility because no whitening flaws occurred inside the sheet even when it was repeatedly folded 50 times or more under the conditions of a load of 9.8 N, an angle of 135°, and a speed of 175 times/min. rice field. In addition, even if the transparent incombustible sheet falls from the installation location in the event of a disaster, it will never break, and there is a low possibility of injury due to fragments, etc., so it can be applied to smoke-proof hanging walls.

The manufacturing method of the present application will be described.
The nonflammable sheet of the present invention is produced by (1) the step of producing an intermediate layer, and (2) the step of laminating a vinyl chloride resin film layer on the intermediate layer.

(1) Step of Producing Intermediate Layer The intermediate layer is produced by impregnating a glass fiber fabric with a styrene-based thermoplastic elastomer.
A solution impregnation method can be used as the impregnation method.
First, a styrene-based thermoplastic elastomer solution (impregnation liquid) is prepared by dissolving and diluting to a predetermined concentration with a predetermined solvent, and the glass fiber fabric is immersed. At this time, additives may be added to the impregnating liquid as required.
Next, after the glass fiber fabric is sufficiently impregnated with the impregnation liquid, the glass fiber fabric is taken out and pressed with rolls to squeeze out the excess solution, or while removing the excess solution by its own weight without pressing with rolls, Heat and dry at a predetermined temperature to obtain an intermediate layer.

Cyclohexane, toluene, xylene, tetrahydrofuran (THF), chloroform, and the like can be used as a solvent for dissolving the styrene-based thermoplastic elastomer, and among them, toluene is preferable from the viewpoint of work efficiency.

Also, the concentration of the impregnating liquid is preferably 10 to 30% by weight. If the concentration is less than 10% by weight, the glass fiber fabric can be easily impregnated with the solution, but the amount of resin adhered tends to be small, making it difficult to obtain the desired transparency. On the other hand, if it exceeds 30% by weight, the viscosity of the solution increases, making it difficult to impregnate the glass fiber woven fabric with the solution, which may reduce transparency and production efficiency.
At this time, the viscosity of the impregnating liquid is preferably 50 to 2500 cps in terms of impregnation and resin adhesion amount.

As another impregnation method, a film coated with a paste-like styrene-based thermoplastic elastomer solution dissolved and diluted with a predetermined solvent to a predetermined concentration is laminated on both sides of the glass fiber fabric and thermocompression bonded to the resin. is impregnated with, heated and dried at a predetermined temperature, and then the film is peeled off to obtain the intermediate layer.

Further, the transparent noncombustible sheet obtained by the solution impregnation method can be subjected to a treatment such as hot pressing to improve the surface smoothness.

(2) Step of Laminating a Vinyl Chloride Resin Film Layer on the Intermediate Layer Preliminarily prepared vinyl chloride resin films are laminated on both sides of the intermediate layer to integrate them. The method of integration is not particularly limited, but a method of bonding by thermocompression bonding without using an adhesive is preferred.

The noncombustible sheet of the present invention comprises an intermediate layer formed by impregnating a glass fiber fabric with a styrene thermoplastic elastomer, and vinyl chloride resin film layers laminated on both sides of the intermediate layer, and a styrene thermoplastic elastomer is used. Therefore, it is possible to adjust the refractive index and flexibility without adding a plasticizer to the resin impregnated into the glass fiber fabric, and the transparency does not deteriorate over time and can be maintained for a long period of time. Furthermore, since the styrene-based thermoplastic elastomer has excellent impregnating properties into the glass fiber fabric and adhesion properties with the vinyl chloride resin film layer, even if the sheet is repeatedly folded and folded, whitening damage will not occur inside the sheet. No, it is flexible.
In particular, by using a hydrogenated styrene-based thermoplastic elastomer in which the hydrogenated butadiene portion has an SP value of 17.5 (J/cm ³ ) ^1/2 or more, the impregnation of the glass fiber fabric is improved. , the transparency is increased (the haze value is lowered), and the occurrence of whitening flaws due to bending or folding can be further suppressed. In addition, it has excellent adhesiveness to the vinyl chloride resin film layer, does not peel off, and does not impair flexibility.
Further, since the vinyl chloride resin film layers are provided on both sides of the intermediate layer, it is possible to carry out a heat welding process, and it is easy to join the width of the sheet.

The present invention will be described below using examples, but the present invention is not limited to these.

[Example 1]
A solution was prepared by dissolving the styrene-based thermoplastic elastomer A in a toluene solvent so that the solid content was 20% by weight, and the solution was surface ^- treated with an aromatic aminosilane. A woven fiber cloth (E-glass fiber, refractive index 1.558) was immersed. At this time, the adhesion amount of the resin was set to 150 g/m ² in a wet state.
Next, in order to volatilize the solvent, it was dried in an oven at 130° C. for 5 minutes to obtain a resin-impregnated glass fiber woven fabric (intermediate layer). The obtained intermediate layer had a resin adhesion amount of 30 g/m ² in a dry state and a thickness of 0.05 mm.
Furthermore, both sides of the intermediate layer were sandwiched between two 120 μm-thick vinyl chloride resin films (manufactured by Achilles Co., trade name “Achilles Fullere”), and pressed with a press at a temperature of 120° C., a pressure of 10 kg/cm ² , and a time of 5 minutes. to obtain a transparent nonflammable sheet with a thickness of 0.29 mm.
The vinyl chloride resin film used contained 29.5% by weight of a plasticizer.

[Example 2]
A transparent noncombustible sheet was obtained in the same manner as in Example 1, except that the thermoplastic styrene-based elastomer B was used as the resin for impregnating the glass fiber fabric.

[Example 3]
A transparent noncombustible sheet was obtained in the same manner as in Example 1, except that the styrene-based thermoplastic elastomer C was used as the resin with which the glass fiber fabric was impregnated.

[ Reference Example 4]
A transparent noncombustible sheet was obtained in the same manner as in Example 1, except that the thermoplastic styrene-based elastomer D was used as the resin for impregnating the glass fiber fabric.

[ Reference Example 5]
A transparent noncombustible sheet was obtained in the same manner as in Example 1, except that the styrene-based thermoplastic elastomer E 2 was used as the resin to be impregnated into the glass fiber fabric.

[Comparative Example 1]
4 parts by weight of a curing agent (benzoyl peroxide) and 25 parts by weight of a styrene monomer are added to 100 parts by weight of a vinyl ester resin (manufactured by Japan U-Pica Co., Ltd., trade name "Neopol 8125"), and stirred for 30 minutes to obtain a resin composition. made things. A glass fiber woven fabric (E glass fiber, refractive index 1.558) having a thickness of 29 μm and a basis weight of 31.5 g/m ² surface-treated with acrylsilane was immersed in this resin composition for 30 minutes.
Then, both sides of the glass fiber woven fabric impregnated with the resin solution were sandwiched between two polyethylene terephthalate films having a thickness of 100 μm, air bubbles were removed with a roller, and the resin was hardened by holding in an oven at 100° C. for 10 minutes. rice field. After curing the resin, the polyethylene terephthalate film was peeled off to obtain a resin-impregnated glass fiber woven fabric (intermediate layer). The obtained intermediate layer had a resin adhesion amount of 31 g/m ² in a dry state and a thickness of 0.05 mm.
Two vinyl chloride resin films having a thickness of 120 μm were adhered to both surfaces of the obtained intermediate layer using a urethane adhesive to obtain a transparent nonflammable sheet having a thickness of 0.29 mm.

[Comparative Example 2]
200 parts by weight of torque resin phosphate, 50 parts of di-2-ethylhexyl phthalate, 2 parts of zinc stearate, and 2 parts of barium stearate are added to 100 parts by weight of polyvinyl chloride resin, and the mixture is stirred for 30 minutes. A resin composition was produced. A glass fiber woven fabric (E glass fiber, refractive index 1.558) having a thickness of 29 μm and a basis weight of 31.5 g/m ² surface-treated with an aromatic aminosilane was immersed in this resin composition.
Then, it was heat-treated at 180° C. for 1 minute to be gelled to obtain a resin-impregnated glass fiber woven fabric (intermediate layer). The obtained intermediate layer had a resin adhesion amount of 30 g/m ² in a dry state and a thickness of 0.05 mm.
Then, both sides of the obtained intermediate layer were sandwiched between two vinyl chloride resin films and pressed with a press under conditions of a temperature of 120° C., a pressure of 10 kg/cm ² and a time of 5 minutes to form a transparent nonflammable sheet with a thickness of 0.29 mm. got

The sheets obtained in Examples 1 to 3, Reference Examples 4 and 5, and Comparative Examples 1 and 2 were evaluated as follows. Results are shown in Table 1.

〔transparency〕
Using a haze meter (manufactured by Suga Test Instruments Co., Ltd., trade name "HZ-V3"), the total light transmittance and haze value were measured to evaluate the transparency of the sheet.
The transparent nonflammable sheet of the present invention has a total light transmittance of 80% or more and a haze value of 30% or less.

[Impregnability]
Using a digital microscope (manufactured by Keyence Corporation, trade name "VHX-5000"), the sample was observed at a magnification of 200 times, and the glass fiber was visible without being impregnated with resin for the total area of 2.4 mm ² . The area ratio of the location was calculated by calculating the area of the luminance extraction region, and evaluated according to the following criteria.

◎: Less than 10% ○: 10% or more and less than 15% △: 15% or more and less than 20% ×: 20% or more

[Maintenance of transparency]
For the purpose of verifying the change in transparency over time, the transparent noncombustible sheet immediately after production was placed in a dryer and an accelerated test was conducted at 40°C for 8 weeks. The haze value of the sheet after the accelerated test was measured.
When the rate of change in haze value between before and after the accelerated test was 10% or more, the transparency was not maintained over time, and was evaluated as x.

[Flexibility]
Using an MIT folding endurance tester (Tester Sangyo Co., Ltd., product name "BE-202S"), using a sample cut to 15 mm × 110 mm, load 9.8 N, angle 135 °, speed 175 times / min After repeatedly bending under the conditions of , the bending portion was observed, and the number of times until whitening damage occurred was evaluated according to the following criteria.

○: 100 times or more △: 50 times or more and less than 100 times ×: less than 50 times

〔Incombustibility〕
Using each sheet, a heat build-up test was conducted with a cone calorimeter tester in accordance with Article 2, Item 9 of the Building Standards Law and Article 108-2 of the Enforcement Order of the Building Standards Law. Samples in which the maximum heat release rate after the start of heating did not exceed 200 kW/m ² continuously for 10 seconds or more and the total calorific value was 8 MJ/m ² or less were accepted, and the others were rejected.

Styrenic thermoplastic elastomers used in the examples:
A: SEBS (manufactured by Asahi Kasei Chemicals, trade name “S.O.E.S1605”)
SP value of hydrogenated butadiene portion (hereinafter referred to as SP value)
17.5 (J/cm ³ ) ^1/2 or more, refractive index 1.559, Tg 18°C
B: SEBS (manufactured by Asahi Kasei Chemicals, trade name “S.O.E.S1606”)
SP value 17.5 (J/cm ³ ) ^1/2 or more, refractive index 1.536, Tg -13°C
C: SEBS (manufactured by Asahi Kasei Chemicals, trade name “S.O.E.S1611”)
SP value 17.5 (J/cm ³ ) ^1/2 or more, refractive index 1.530, Tg 9°C
D: SEBS (manufactured by Asahi Kasei Chemicals, trade name “Tuftec H1043”)
SP value 17.5 (J/cm ³ ) less than ^1/2 , refractive index 1.549, Tg -55°C
E: SEBS (manufactured by Asahi Kasei Chemicals, trade name “Tuftec H1051”)
SP value 17.5 (J/cm ³ ) less than ^1/2 , refractive index 1.525, Tg -44°C

According to Examples 1 to 5, the present invention is a transparent noncombustible sheet that does not cause whitening flaws inside the sheet even after repeated bending and folding, has excellent flexibility, and can maintain transparency for a long period of time. In particular, Examples 1 to 3 use a styrenic thermoplastic elastomer having a hydrogenated butadiene portion with an SP value of 17.5 (J/cm ³ ) ^1/2 or more. The impregnability of the resin was superior, and the flexibility was also good.

Claims (3)

an intermediate layer formed by impregnating a glass fiber fabric with a styrene-based thermoplastic elastomer;
A vinyl chloride resin film layer is laminated on both sides of the intermediate layer,
The addition amount of the plasticizer in the vinyl chloride resin film layer is 15 to 40% by weight with respect to 100% by weight of the film,
A transparent noncombustible sheet, wherein the styrene-based thermoplastic elastomer is hydrogenated and has a glass transition temperature of -20°C to 20°C. 2. The transparent noncombustible sheet according to claim 1, wherein a difference in refractive index between said glass fiber fabric and said styrene-based thermoplastic elastomer is 0.03 or less. 3. The transparent noncombustible sheet according to claim 1, wherein the sheet has a total light transmittance of 80% or more and a haze of 30% or less.