JP5818489B2 - Combustion resistant sheet - Google Patents

Description

  The present invention relates to a flame resistant sheet.

Conventionally, thermoplastic resin has been used as a plant plate, pipe, pipe joint, sheet as a material having excellent physical properties such as impact resistance and heat resistance and chemical properties such as solvent resistance and acid resistance. It is used for many applications such as film.
However, when it burns, toxic gas, a large amount of black smoke, etc. are generated, and in vehicle applications such as trains, the safety of passengers is impaired in the event of a fire.

As a method for improving the flame retardancy of a thermoplastic resin, for example, a method of adding a flame retardant such as aluminum hydroxide or magnesium hydroxide to a vinyl chloride resin has been proposed (for example, see Patent Document 1).
Further, a method of adding graphite to a vinyl chloride resin has been proposed (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 5-25347 JP 09-227747 A

  However, with such a thermoplastic resin composition, Section 83, “Fire Control for Vehicles,” in Section 5 of the “Ministerial Ordinance for Establishing Technical Standards Regarding Railways (Ministry of Land, Infrastructure, Transport and Tourism Ordinance No. 151, December 25, 2001)” In a combustion test conducted by a method compliant with the above, a large amount of filling is required in order to develop a combustion suppression effect, and therefore, physical properties such as impact resistance and secondary workability such as vacuum formability are significantly reduced. There was a drawback of inviting.

  This invention is made | formed in view of the said problem, and it aims at providing the flame-resistant sheet | seat excellent in the flame retardance and secondary workability.

The flame resistant sheet of the present invention is a flame resistant sheet in which a flame resistant layer composed of a flame resistant resin composition and a decorative layer are laminated,
The flame resistant layer is formed of a flame resistant resin composition containing graphite and a thermoplastic resin, and is defined by [thickness of the flame resistant layer] × [thermal conductivity of the flame resistant layer]. The thermal conductivity of the combustible layer] is 3.4 mW / K or more,
The decorative layer includes a vinyl chloride resin and an acrylic resin, and a tensile elastic modulus at 23 ° C. based on ASTM D638 is 2,500 MPa or less.

  ADVANTAGE OF THE INVENTION According to this invention, the flame-resistant sheet | seat excellent in the flame retardance and secondary workability can be provided.

(Flame resistant sheet)
The combustion resistant sheet of the present invention is configured by laminating a combustion resistant layer and a decorative layer. The decorative layer is disposed on the surface of the flame resistant sheet. By disposing the decoration layer on the surface of the flame resistant sheet, for example, excellent processing characteristics of the material constituting the decoration layer can be exhibited.
Moreover, the coating layer may be laminated | stacked on the flame-resistant sheet | seat of this invention. In order to efficiently express the combustion resistance effect of the coating layer, on the back side of the flame resistance layer, to compensate for the deterioration of secondary workability such as impact resistance and vacuum formability due to graphite of the flame resistance layer. It is preferable to arrange. Furthermore, in addition to these layers, various functional layers such as a protective layer and an antireflection layer may be formed.
The flame resistant layer may have a multilayer structure with different thermal conductivities. Further, depending on the purpose, it may be a three-layer structure in which coating layers are laminated on both the front and back surfaces of the flame resistant layer, or a laminated structure of four or more layers such as these layers being alternately laminated. It may be. In this case, the decorative layer is preferably disposed on the outermost surface of the combustion resistant sheet.
In addition, in this application, when using a combustion-resistant sheet | seat as interior materials, such as a railway vehicle, the surface exposed to a passenger side is called the surface.

(Flame resistant layer)
The flame resistant layer only needs to be formed of a flame resistant resin composition containing at least graphite and a thermoplastic resin. The flame resistant layer may be a single layer structure made of a flame resistant resin composition, but is formed of, for example, a thermoplastic resin and different types of fillers such as fine metal particles such as copper and aluminum or fine fibers. A multilayer structure in which a layer and a layer formed of a flame resistant resin composition are arbitrarily combined may be used. Thus, by combining specific materials, the excellent characteristics of the materials themselves can be sufficiently exhibited. Thereby, a flame retardance can be improved as interior materials, such as a rail vehicle, for example.

(graphite)
The graphite is not particularly limited, and various conventionally known ones can be used. Either natural graphite or artificially produced graphite may be used. For example, scaly graphite, scaly graphite, scaly (lumpy) graphite, earthy graphite, artificial graphite, expanded graphite, expanded graphite, pyrolytic graphite and the like can be mentioned. These graphites may be refined, dried, fired, pulverized and / or classified. The pulverization process is not particularly limited, and can be performed using a conventionally known apparatus such as a rod mill, a ball mill, or a jet mill.
Thus, by adding graphite to the thermoplastic resin, the flame resistance can be remarkably improved in the flame resistant sheet. Therefore, a combustion test conducted by a method in accordance with Article 83 of Section 5 of the Fire Countermeasures for Vehicles in the "Ministerial Ordinance for Establishing Technical Standards on Railways (December 25, 2001, Ministry of Land, Infrastructure, Transport and Tourism Ordinance No. 151)" In this case, the effect of suppressing the ignition of the specimen can be expressed.

The carbon source used as the raw material of the graphite described above is not particularly limited, and may be any of naturally occurring materials, artificially produced materials such as natural graphite and quiche graphite.
The shape of the carbon source used as the raw material for graphite and the coke described later may be either solid or powder.

  Scaly graphite is a kind of naturally produced graphite and is conventionally known, and is not particularly limited. Any graphite can be used. Scalar graphite is preferable because it has a large aspect ratio of particles, allows heat to escape more in the plane direction than in the thickness direction, and improves the flame retardancy of the interior material. Further, the scaly graphite includes scaly graphite having a larger aspect ratio, exfoliated graphite, and the like. Generally, the aspect ratio of flake graphite is about 30, and the aspect ratio of exfoliated graphite is about 100.

  Artificial graphite is artificially produced by heating a carbon source as a raw material at a high temperature, and any graphite can be used as long as it is conventionally known. For example, graphite obtained by heat-treating coke includes that produced by pulverizing an artificial graphite electrode produced by heat-treating a binder such as coke and coal tar at a high temperature of 2000 ° C. or higher. What does not contain binders, such as coal tar, is preferred because of its high thermal conductivity.

  The expanded graphite is a conventionally known one, and is not particularly limited, and any one can be used. Usually, it is produced by chemically treating graphite. For example, natural scale-like graphite, pyrolytic graphite, quiche graphite and other powders such as concentrated sulfuric acid, nitric acid, selenic acid and other inorganic acids and concentrated nitric acid, perchloric acid, perchlorate, permanganate, dichromate, Examples include crystalline compounds that maintain a carbon layer structure obtained by inserting an inorganic acid between graphite layers using a strong oxidizing agent such as hydrogen peroxide and performing acid treatment.

The expanded graphite is obtained by expanding the expanded graphite. The method for expanding is not particularly limited. For example, a method of performing a heat treatment for several minutes to several hours at a temperature of several hundred to 1,000 degrees in a furnace and the like can be mentioned.
Expanded graphite expands expanded graphite and then increases the surface area of the graphite by opening the interlayer of the graphite that has been pulverized, thus increasing the probability that the graphites are closer together after molding the flame resistant sheet. Conceivable.

Pyrolytic graphite is artificially produced by heating a carbon source as a raw material at a high temperature, and any graphite can be used as long as it is conventionally known. . Pyrolytic graphite is produced by, for example, heat-treating a coke raw material at a high temperature of 2000 to 3000 ° C. or higher, or by heating the graphite at a high temperature (about 2000 to 3000) in a hydrocarbon atmosphere. And those produced by carbon deposition on the graphite surface. The graphite is not particularly limited, and may be any naturally occurring one, artificially produced one, such as natural graphite or quiche graphite. The shape of graphite and coke may be solid, powder, or the like.
Pyrolytic graphite is particularly preferred because the flame resistance is enhanced by its thin shape and high degree of graphitization by high temperature treatment.
Note that pyrolytic graphite includes graphite obtained by heat treating coke, including coke powder that is heat treated at a high temperature of 2000 ° C. or higher when producing SiC, and has a tendency to increase the thermal conductivity with less impurities. Therefore, it is particularly preferable.

  The size and shape of graphite to be used are not particularly limited, but considering the dispersibility and / or physical properties of the thermoplastic resin, the average particle size is preferably about 500 μm or less, more preferably about 300 μm or less. . Considering the thermal conductivity described later, the larger one is preferable because the probability of contact between graphites increases (the probability of contact with a material such as a thermoplastic resin having low thermal conductivity decreases) and the thermal conductivity increases. In order to ensure a certain degree of thermal conductivity, it is preferably about 15 μm or more. In order to maintain good dispersibility, moldability and the like in the molded body, about 25 μm to 200 μm is more preferable, and about 30 to 100 μm is particularly preferable. If the average particle size is too small, the bulk specific gravity increases, which may cause inconvenience in handling. Here, the particle size is, for example, a value measured by using a laser diffraction particle size distribution analyzer SALD-2200 (manufactured by Shimadzu Corporation) after sufficiently dispersing graphite in a THF solution.

  In addition, when the flame-resistant sheet of the present invention is used as an interior material for a railway vehicle, the shape of graphite is a thin plate rather than a spherical shape from the viewpoint of delaying ignition by quickly releasing heat from a flame during a fire. The shape is preferable, and this makes it easier to release heat in the plane direction than in the thickness direction, and the flame retardancy of the interior material can be improved. For this reason, those having a large aspect ratio are preferred. In particular, when a combustion-resistant sheet is used as an interior material for a railway vehicle, it is preferable to orient the graphite having a long diameter along the surface direction of the interior material. This makes it possible to efficiently release heat from the flame.

The degree of graphitization of graphite is an index of crystallinity that is directly measured by the half-value width of X-ray diffraction, which will be described later. In graphite, if the value is high (if the half-value width is small), the thermal conductivity becomes high and difficult. From the viewpoint of improving flammability, a higher one is more preferable. For the same purpose, graphite having less impurities is more preferable.
The relative degree of graphitization can be measured, for example, by the following method.
The full width at half maximum (FWHM) of the largest peak appearing in the vicinity of 52 ° to 57 ° by 2θ is measured by X-ray diffraction. The smaller this value, the higher the graphitization degree.
For example, when this half-value width is measured using an X-ray diffractometer manufactured by Brugger AXS, the half-value width is 0.47 for earth-like graphite and 0.53 for artificial graphite, and graphitization has not progressed. Graphite, scaly graphite, and pyrolytic graphite are preferable because they are as small as about 0.23 and have a high degree of graphitization, thus increasing the thermal conductivity. Among them, pyrolytic graphite is particularly preferable because it is not only highly graphitized but also thinner and has less impurities.
The graphitization degree of the graphite used in the present invention is not limited, but the above-described half-value width is suitably 0.4 or less, preferably 0.35 or less, more preferably 0.3 or less.

When the content of graphite increases with respect to the flame-resistant resin composition containing a thermoplastic resin, the flame-resistant resin composition, a sheet (single layer) comprising the composition, and the flame-resistant sheet of the present invention Increase the thermal conductivity. Therefore, the graphite content is, from one point of view, the thermal conductivity of the combustion-resistant resin composition, that is, the thermal conductivity when the combustion-resistant resin composition is a single layer is 1.4 W / m · K or more. It is suitable to be in the range. In order to impart higher flame retardancy, such as when used as an interior material for railway vehicles, it is preferably 3.0 W / m · K or more, more preferably 4.6 W / m · K or more, and 5.8 W. / M · K or more is more preferable.
The upper limit of the thermal conductivity is suitably 25 W / m · K or less, preferably 13 W / m · K or less, and more preferably 8 W / m · K or less.
In addition, since the content for obtaining the above-described thermal conductivity may vary depending on the type or state of graphite, for example, it is preferable to adjust graphite appropriately in consideration of the content described later.

In the present invention, the thermal conductivity means a value measured as follows.
As an example of a method for producing a test piece, a resin composition is supplied to a twin screw extruder, melt-kneaded, and has a predetermined thickness (for example, 1 mm to several tens mm, specifically 3.2 mm). There is a way to get a sheet.
As another example, the resin composition is supplied to a kneader and melt-kneaded at a temperature of about 185 ° C. to obtain a sheet having a thickness of 1 mm. Next, the plurality of sheets are laminated and supplied to a hot press molding machine, and pressurized at a temperature of 190 ° C. and 7 MPa to obtain a 3.2 mm sheet.
The thermal conductivity is a value specific to the material, but may be affected by the base when the thickness of the measurement target layer is about 10 mm or less or in the case of a laminated structure. When the measurement target layer is about 10 mm or less or in the case of a laminated sheet, only the measurement target layer may be isolated and used as a test piece.
The test piece described above is placed on a standard plate (silicon, quartz, zircon brick) with a known thermal conductivity so that the test piece is closely adhered to the surface of the test piece at room temperature using a thermal conductivity meter. Apply the probe to measure the thermal conductivity. Here, as the thermal conductivity meter, Chemtherm. QTM-D3 (trade name) (manufactured by Kyoto Electronics Industry Co., Ltd.) can be used.
Subsequently, the thermal conductivity of the standard plate and the deviation of the measured thermal conductivity are plotted, and the thermal conductivity is obtained from the intersection of the obtained straight line and the deviation = 0.

In the flame-resistant sheet of the present invention, in order to effectively develop the flame resistance, it is suitable to adjust the thermal conductivity of the above-mentioned flame-resistant layer to a predetermined range. It is preferable to consider the thickness of the combustion resistant layer in the thermal conductivity of the conductive layer.
The total thickness of the flame resistant layer is not particularly limited in either a single layer or a laminate structure of two or more layers, and can be appropriately adjusted depending on the material, required characteristics, and the like. The thicker the flame resistant layer, the greater the flame resistant effect and the lower the graphite content. This is advantageous in terms of physical properties such as impact resistance and secondary workability such as vacuum formability. For example, 0.1 mm or more is mentioned. Moreover, 0.2 mm or more is suitable for the total thickness of a combustion-resistant layer, 0.8 mm or more is preferable and 2 mm or more is more preferable. If the total film thickness of the flame resistance is too small, the flame resistance tends to be hardly exhibited even if the thermal conductivity of the flame resistance layer is increased.
Therefore, the total thickness of the flame resistant layer contributing to heat dispersion is 0.2 mm or more, and [combustion resistant] defined by [thickness of the flame resistant layer] × [thermal conductivity of the flame resistant layer]. It is suitable to adjust the thermal conductivity of the layer] to 3.4 mW / K or more. Further, the heat conduction amount of the combustion resistant layer is preferably 7.2 mW / K or more, more preferably 11.0 mW / K or more, and particularly preferably 13.9 mW / K or more.
In addition, when the flame resistant layer is composed of a plurality of flame resistant layers having different thermal conductivities, [the thermal conductivity of the flame resistant layer] = [of the first flame resistant layer] Thickness] × [Thermal conductivity of the first flame-resistant layer] + [The thickness of the second flame-resistant layer] × [Thermal conductivity of the second flame-resistant layer] +... + It means [thickness of nth layer of flame resistant layer] × [thermal conductivity of nth layer of flame resistant layer].

From another point of view, the graphite content is preferably 36.0% by weight or more based on the total weight of the combustion-resistant resin composition. More preferably, it is 50.5 weight% or more, More preferably, it is 59.1 weight%. If the content is too large, the moldability may be deteriorated, and therefore it is preferably 80% by weight or less. More preferably, it is 70 weight% or less. Therefore, it is suitable to contain in 30 to 80 weight%, Preferably it is 40 to 70 weight%, More preferably, it is 50 to 70 weight%. By setting it as this range, while being able to acquire a suitable thermal conductivity and a flame-retardant effect, the fall of a moldability can be prevented.
In particular, the content of graphite dominates the magnitude of the thermal conductivity as described above, but is affected by the shape as described later, the manufacturing method of the flame-resistant sheet, etc. And it is more preferable to adjust suitably in the range used as content mentioned above.

(Thermoplastic resin / combustion-resistant resin composition)
It does not specifically limit as a thermoplastic resin, A conventionally well-known various thing can be used. However, the thermoplastic resin here excludes a resin generally functioning as a processing aid, particularly a processing aid described later. For example, polyolefin resin such as polypropylene resin and polyethylene resin; poly (1-) butene resin, polypentene resin, polycarbonate resin, polyphenylene ether resin, acrylic resin, styrene resin [for example, polystyrene (resistant Impact polystyrene), acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene (AS) resin, acrylonitrile-ethylene-propylene-styrene (AES) resin, acrylonitrile-acrylate-styrene (AAS) resin, etc.), polyamide Resin, chlorinated polyethylene, vinyl chloride resin, chlorinated vinyl chloride resin, ethylene copolymer [for example, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer (EMA), Len - ethyl acrylate copolymer (EEA), ethylene - butyl acrylate copolymer (EBA), ethylenemethyl - methyl methacrylate copolymer (EMMA), and the like also like including] AES described above. These may be used alone or in combination of two or more. Among these, vinyl chloride resin with excellent combustion resistance and chlorine with excellent impact resistance and secondary processability can compensate for the decrease in impact resistance due to the addition of graphite and secondary processability such as vacuum formability. Preferred is a modified polyolefin. Further, when a vinyl chloride resin is used, the interlayer adhesion is further strengthened and advantageous in that a decorative layer and / or a coating layer containing the vinyl chloride resin is laminated.

Although the molecular weight of the thermoplastic resin used by this invention is not specifically limited, For example, the weight average molecular weight of about 10,000-1 million is mentioned. This weight average molecular weight is a polystyrene-reduced weight average molecular weight measured by GPC (gel permeation chromatography) of a styrene elastomer (hereinafter, the same method for measuring the weight average molecular weight).
In particular, in the method for measuring the weight average molecular weight of the (meth) acrylate polymer, it can be a value specifically measured under the following conditions.
Apparatus: HLC-8120 (manufactured by Tosoh Corporation),
Solvent: Using THF, a calibration curve is prepared according to the molecular weight of polystyrene having a known molecular weight.
The column is appropriately selected depending on each molecular weight. For example, in the case of 3 million or more,
Column used: GMHHR-H (30) × 2 Solvent: THF, sample concentration: 0.05%, injection amount: 50 μl, flow rate: 0.5 ml / min, the sample concentration is also adjusted depending on the molecular weight.

  Vinyl chloride resin is a copolymer of vinyl chloride homopolymer (vinyl chloride homopolymer), a monomer having an unsaturated bond copolymerizable with vinyl chloride monomer, and vinyl chloride monomer (preferably containing 50% by weight or more). Examples thereof include a graft copolymer obtained by graft copolymerizing a vinyl chloride monomer with a polymer or a polymer. These polymers may be used alone or in combination of two or more.

  Examples of the monomer having an unsaturated bond copolymerizable with vinyl chloride monomer include α-olefins such as ethylene, propylene, and butylene; vinyl esters such as vinyl acetate and vinyl propionate; butyl vinyl ether, cetyl vinyl ether, and the like. Vinyl ethers; (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl acrylate, and phenyl methacrylate; aromatic vinyls such as styrene and α-methylstyrene; vinylidene chloride, vinylidene fluoride, etc. And halogenated vinyl vinyls; N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide; (meth) acrylic acid, maleic anhydride, acrylonitrile and the like. These may be used alone or in combination of two or more.

  The polymer for graft copolymerization of vinyl chloride resin is not particularly limited as long as the vinyl chloride resin is graft polymerized. For example, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-carbon monoxide copolymer , Ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate-carbon monoxide copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, acrylonitrile-butadiene copolymer, polyurethane, chlorinated polyethylene, chlorine And polypropylene. These may be used alone or in combination of two or more.

  The polymerization method of the vinyl chloride resin is not particularly limited, and any conventionally known polymerization method can be used. Examples thereof include a bulk polymerization method, a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method.

The chlorinated vinyl chloride resin may be polymerized using a material chlorinated before polymerization of the vinyl chloride monomer, or may be chlorinated after polymerizing the vinyl chloride resin.
The method for chlorinating the vinyl chloride resin is not particularly limited, and a conventionally known chlorination method can be used. Examples thereof include a thermal chlorination method and a photochlorination method.

When the degree of polymerization of the vinyl chloride resin decreases, mechanical properties tend to decrease, and when it increases, moldability tends to deteriorate. Therefore, it is preferably about 400 to 2500, more preferably about 600 to 2000, 600 About 1600.
Examples of the method for adjusting the degree of polymerization mainly include the polymerization temperature. In general, the higher the polymerization temperature, the lower the degree of polymerization. The degree of polymerization can be measured according to JIS K 6720-2.

  Chlorinated polyolefins, such as chlorinated polyethylene, are chlorinated parts of polyethylene, and are generally used alone as elastomers with excellent flexibility, weather resistance, heat aging resistance, flame resistance, and chemical resistance. . Further, it is used as a physical property improver for general purpose resins such as vinyl chloride resin, olefin resin, ABS, or rubbers such as EPDM, chlorosulfonated polyethylene, chloroprene, SBR. Of these, chlorinated polyethylene is preferably used. Chlorinated polyethylene can be obtained using a conventionally known chlorination method.

When graphite is added to the resin component, the elastic modulus is remarkably increased and the entire composition becomes rigid, so that the elongation at high temperature required for impact resistance and secondary workability may be lowered. In particular, by using chlorinated polyethylene, the impact resistance reduced by graphite can be efficiently compensated by taking a network structure in a matrix that has become harder and brittle due to the addition of graphite and imparting flexibility, It is considered that the effect of improving elongation at high temperatures is exhibited.
The weight average molecular weight of about 50,000 to 400,000 is suitable for chlorinated polyethylene, and it is preferable that it is in a relatively high range (for example, about 320,000 or more). The degree of chlorination is suitably about 20% to 40%. Furthermore, it is preferable that the molecular weight is about 150,000 to 350,000 and the degree of chlorination is 25% to 36%.
In particular, when other resins are contained in the flame resistant resin composition, by setting the molecular weight within this range, it is possible to prevent other resins (for example, vinyl chloride resin, (meth) acrylate polymer, etc.). It is possible to improve the compatibility by developing entanglement at the molecular chain level. Also, by relatively increasing the degree of chlorination (for example, about 34% or more), imparting a polarity close to that of other resins (for example, vinyl chloride resin, acrylic processing aids, etc.) and improving compatibility. It is thought that you can.

  The content of the thermoplastic resin is not particularly limited, and is preferably adjusted appropriately in consideration of the kind of the thermoplastic resin, secondary processability such as vacuum forming, moldability, and combustibility. For example, the thermoplastic resin is 1% by weight or more, preferably 5% by weight, more preferably 8% by weight or more, and particularly preferably 15% by weight or more based on the total flame-resistant resin composition. Moreover, as an upper limit, it is 85 weight% or less, Preferably it is 60 weight% or less, More preferably, it is 40 weight% or less, Most preferably, it is 30 weight% or less. If the content is too small, the physical properties tend to deteriorate. On the other hand, if the content is too large, the amounts of graphite, other resins, etc. are reduced, and the combustibility and secondary processability may be reduced.

It is preferable that an acrylic processing aid for improving secondary processability is added to the flame resistant resin composition. By adding an acrylic processing aid, the vacuum formability can be improved. The acrylic processing aid is also excellent in compatibility with various combustion-resistant resin compositions.
Examples of acrylic processing aids include (meth) acrylate polymers. The (meth) acrylate polymer is a general term for polymers mainly composed of acrylate monomers or methacrylate monomers, and serves as a processing aid.
For example, homopolymers or copolymers of (meth) acrylate monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate; the above (meth) acrylate monomers and styrene, vinyltoluene, acrylonitrile And copolymers with other monomers. You may use these individually or in combination of 2 or more types.

The content of the acrylic processing aid can be adjusted as appropriate in consideration of the content of graphite, secondary processability such as vacuum forming reduced by the addition of graphite, formability and combustibility.
In the flame resistant resin composition, when the content of graphite increases, the content of the (meth) acrylate polymer needs to be increased for the purpose of preventing deterioration of moldability. On the other hand, in the case where decoration such as laminate of vinyl chloride resin is applied to the surface layer, in order to determine that there is no ignition (non-combustion) in the vehicle flammability test, the graphite content (ratio to the composition) Therefore, the amount of (meth) acrylate polymer that can be added is limited. Therefore, the content of the (meth) acrylate polymer is 1% by weight or more, preferably 4% by weight, more preferably 12% by weight or more, and particularly preferably 23% by weight with respect to the total weight of the flame resistant resin composition. % Or more. Moreover, as an upper limit, it is 60 weight% or less, Preferably it is 40 weight% or less, 30 weight% or less. For example, 1-60 weight%, 4-40 weight%, 12-40 weight%, 12-30 weight% etc. are mentioned. By setting to this range, it is possible to achieve both improvement in combustion resistance due to the addition of graphite and secondary workability. If the content is too large, the amount (ratio) of the thermoplastic resin is decreased, and the physical properties are further deteriorated.

The vacuum forming of the flame resistant resin composition is generally performed by heating the surface temperature of the resin composition to about 180 ° C to 220 ° C. In such a high temperature state, the tension of the combustion-resistant resin composition, for example, polyvinyl chloride resin may be reduced and may be easily broken. Therefore, a (meth) acrylate polymer having a higher tension in the high temperature region is preferably used. When an inorganic material, particularly a non-spherical type inorganic material such as graphite, is added, it tends to break at a high temperature, so the addition of (meth) acrylate polymer is effective.
As the compound for improving elongation at high temperature, thermoplastic elastomers such as NBR (nitrile butadiene rubber) and Elvalloy, and plasticizers such as DOP (dioctyl phthalate) can be used. From the viewpoint of imparting tension at high temperature ( A meth) acrylate polymer is particularly preferred.

  The weight average molecular weight of the (meth) acrylate polymer is not particularly limited. However, higher molecular weight is preferable from the viewpoint of higher tension at high temperature. For example, it is preferably 1 million or more, more preferably 3 million or more. On the other hand, if the molecular weight is too high, the moldability and physical properties are adversely affected. More preferably, it is 5 million or less.

It is preferable that an impact modifier excellent in impact resistance is added to the combustion resistant resin composition.
The impact modifier is not particularly limited as long as it is usually used in the field. For example, methyl methacrylate-butadiene-styrene graft copolymer (MBS resin), chlorinated polyethylene (CPE), ABS. Examples thereof include resins and acrylic modifiers. These may be used alone or in combination of two or more.
Here, the acrylic modifier is at least one acrylic copolymer selected from the group consisting of one of acrylic acid esters or methacrylic acid esters, in particular an acrylic component as a main component, and is crosslinked and spherical. The one that became. Among them, chlorinated polyethylene that can effectively compensate for the impact resistance reduced by graphite by adopting a network structure in a matrix that has become hard and brittle by the addition of graphite and imparting flexibility is suitably used. .
The content of the impact modifier can be appropriately adjusted in consideration of the content of graphite, the type of impact modifier, and the like.

  In addition to the acrylic processing aid and / or impact modifier described above, various additives may be added to the flame resistant resin composition of the present invention. Examples of the additive include a flame retardant, a heat stabilizer, a stabilizing aid, a lubricant, an antioxidant, a light stabilizer, and a pigment for the purpose of assisting the combustion suppressing effect. You may use these individually or in combination of 2 or more types.

  Examples of the flame retardant include antimony oxide such as antimony dioxide, antimony trioxide, and antimony pentoxide, molybdenum compounds such as molybdenum trioxide, molybdenum disulfide, and ammonium molybdate, and bromines such as tetrabromobisphenol A and tetrabromoethane. Examples thereof include phosphorus compounds such as compounds, triphenyl phosphate, and ammonium polyphosphate.

  Examples of the heat stabilizer include dimethyltin mercapto, dibutyltin mercapto, dioctyltin mercapto, dibutyltin malate, dibutyltin malate polymer, dioctyltin malate, dioctyltin malate polymer, dioctyltin laurate, dibutyltin laurate, dibutyltin Organotin stabilizers such as laurate polymer, lead white, lead stearate, dibasic lead stearate, dibasic lead phosphite, basic lead sulfite, dibasic lead sulfite, tribasic lead sulfate, Lead stabilizers such as silica gel co-precipitated lead oxalate, lead benzoate, lead naphthenate, metal soap stabilizers such as calcium stearate, barium stearate, zinc stearate, calcium-zinc stabilizer, barium-zinc Stabilizer, barium-cadmium stabilizer, hydrotalcite, zeolite, etc. System stabilizer and the like.

  The stabilizing aid is not particularly limited, and examples thereof include epoxidized soybean oil, epoxidized linseed bean oil, epoxidized tetrahydrophthalate, epoxidized polybutadiene, and phosphate ester.

  The lubricant is not particularly limited, and examples thereof include montanic acid wax, paraffin wax, polyethylene wax, stearic acid, stearyl alcohol, and butyl stearate.

Examples of the antioxidant include phenol-based antioxidants, sulfur-based antioxidants, phosphite-based antioxidants, and the like.
The light stabilizer is not particularly limited, and examples thereof include ultraviolet absorbers such as salicylic acid esters, benzophenones, benzotriazoles, and cyanoacrylates, or hindered amine light stabilizers.
The pigment is not particularly limited, and examples thereof include organic pigments such as azo, phthalocyanine, selenium, and dye lakes, oxides, molybdenum chromate, sulfide / selenide, ferrocyanide, and the like. An inorganic pigment etc. are mentioned.

  The addition method and order of addition of the additive are not particularly limited, and can be any method and order. For example, the addition method is not particularly limited, and it can be added to the vinyl chloride resin by a hot blend method, a cold blend method, or the like.

(Decoration layer)
The decorative layer in the flame-resistant sheet of the present invention means a layer that can improve design properties such as characters / patterns, metallic luster, and paint texture, and may be a so-called printing / processing layer.
Such a decorative layer includes a vinyl chloride resin and an acrylic resin. One or more vinyl chloride resins can be appropriately selected from those described above. Examples of the acrylic resin include a homopolymer of (meth) acrylic acid ester, a copolymer of a monomer copolymerizable with (meth) acrylic acid ester, and the like. These may be used alone or in combination of two or more.

  Examples of monomers copolymerizable with (meth) acrylic acid esters include α-olefins such as ethylene, propylene and butylene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as butyl vinyl ether and cetyl vinyl ether. ; (Meth) acrylic esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl acrylate and phenyl methacrylate; aromatic vinyls such as styrene and α-methylstyrene; halogens such as vinylidene chloride and vinylidene fluoride; Vinyl vinyl halides; N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide, (meth) acrylic acid, maleic anhydride, acrylonitrile and the like. These may be used alone or in combination of two or more.

When a large amount of filler such as graphite is added, secondary workability is lowered, and the surface decoration layer becomes thin, and problems such as tearing tend to occur. Therefore, in the combustion resistant sheet of the present invention, this problem can be solved by using an acrylic resin that is excellent in followability during vacuum forming. However, when the acrylic resin alone is used, the combustion resistance is lowered, and therefore, it is preferably composed of a mixture with a vinyl chloride resin.
The ratio of the vinyl chloride resin and the acrylic resin in the decorative layer is not particularly limited, and can be appropriately adjusted depending on the balance of combustion resistance, secondary workability, and the like. For example, about 5-95: 95-5 is mentioned, About 10-90: 90-10 is preferable.

The tensile elastic modulus at 23 ° C. according to ASTM D638 of the decorative layer is suitably about 2,500 MPa or less. By setting it as such a tensile elasticity modulus, the outstanding followable | trackability with respect to a sheet | seat can be exhibited at the time of vacuum forming, and defects, such as a tear of a film, can be suppressed.
In addition to the vinyl chloride resin and the acrylic resin, the decorative layer may contain other resins, for example, additives known in the art. Examples of such additives include those similar to various additives that may be contained in the flame resistant resin composition. Substantially, those made of vinyl chloride resin and acrylic resin are preferable.

The composition and thickness of the decorative layer can be determined in accordance with the thickness of the combustion-resistant layer, the content of graphite, and the like, further considering the above-described heat conduction amount and the like. Thereby, physical properties and secondary workability can be efficiently supplemented without impairing the combustion resistance.
In particular, the decorative layer has a minimum thickness within a range that does not impair the flame resistance, that is, to reduce the influence on the flame resistance or to increase the thermal conductivity within the above-described range. It is preferable. For example, the thickness of the decorative layer may be about 3 mm or less, and is suitably suppressed to about 0.5 mm or less, preferably 0.05 to 0.3 mm.

(Coating layer)
When the coating layer is disposed on the flame-resistant sheet of the present invention, it is suitable to use a highly flame-retardant material (for example, vinyl chloride resin) in consideration of the flame resistance. For example, it is preferably formed of a thermoplastic resin composition containing a thermoplastic resin, more preferably formed of a thermoplastic resin composition containing an impact modifier and / or processing aid, More preferably, it is formed of a thermoplastic resin composition containing a thermoplastic resin, an impact modifier and a processing aid.
One or more thermoplastic resins and impact modifiers can be appropriately selected from those described above. Among them, as the thermoplastic resin, it is preferable to use a styrene resin and / or a vinyl chloride resin. The styrenic resin includes the above-described polymer alloys of the styrenic resin and other resins. For example, an alloy of polycarbonate resin and ABS resin (PC / ABS), an alloy of polycarbonate resin and AES resin (PC / AES), and the like can be given.
As the processing aid, the acrylic processing aid described above is preferable.
In this case, 1 to 30 parts by weight of the impact modifier is suitable for 100 parts by weight of the thermoplastic resin in consideration of improvement in impact resistance, heat resistance, mechanical strength, etc., preferably 3 ~ 20 parts by weight. The processing aid is suitable in an amount of 1 to 30 parts by weight, preferably 3 to 20 parts by weight in consideration of improvement in vacuum formability and surface smoothness of the sheet.

A preferred combination of an impact modifier and a processing aid is an MBS resin (copolymerization of methyl methacrylate, butadiene and styrene), a (meth) acrylate polymer having a weight average molecular weight of 1 to 6 million, chlorinated polyethylene (CPE). ) And a (meth) acrylate polymer having a weight average molecular weight of 1,000,000 to 6,000,000, an acrylic impact modifier and a (meth) acrylate polymer having a weight average molecular weight of 1,000,000 to 6,000,000, or a combination thereof. .
By setting it as such a structure, the flame-resistant sheet excellent in a flame retardance, a physical property, and secondary workability can be obtained.
Various additives may be added to the thermoplastic resin composition constituting the coating layer in the same manner as the combustion resistant resin composition.

  Note that the coating layer and other optional layers are appropriately determined in accordance with the thickness and material of the combustion-resistant layer and the decorative layer, the content of graphite, and the like, further considering the above-described thermal conductivity and the like. be able to.

  As described above, when the combustion-resistant sheet of the present invention is used as an interior material for a railway vehicle or the like, the surface exposed to the passenger side is referred to as the surface thereof. Is evaluated. For example, a combustion test conducted by a method in accordance with Article 83 of Section 5 of the Fire Countermeasures for Vehicles in the Ministerial Ordinance (Ministry of Land, Infrastructure, Transport and Tourism Ordinance No. 151 on December 25, 2001) that establishes technical standards related to railway It becomes one of the indicators.

(Production method of flame resistant sheet)
The flame resistant sheet of the present invention can be formed by any method known in the art. For example, (1) a method of separately forming a flame resistant layer and a decorative layer into a sheet shape, and bonding them together, (2) forming either a flame resistant layer or a decorative layer into a sheet shape, A method of applying the other raw material, (3) a lamination integration method, etc., are provided by co-extrusion of the combustion-resistant layer and the decorative layer by a known method such as an inflation method or a T-die method.
In addition, even when a coating layer or the like is further provided, it can be formed by any one or combination of (1) to (3) described above.

  Examples of the flame resistant sheet of the present invention will be described below, but are not limited to the following examples. In addition, unless otherwise indicated, the part and% in an Example show the value of a weight reference | standard. In addition, the composition of each component in the table indicates% by weight unless otherwise specified.

(material)
The materials used in Examples and Comparative Examples of the present invention are as follows.
(1) Vinyl chloride resin: manufactured by Tokuyama Sekisui Industry Co., Ltd., trade name “TS-800E”, polymerization degree 800
(2) Chlorinated polyethylene (CPE): manufactured by Dow Chemical Co., Ltd., trade name “Tyrin 3615P”
(3) Impact modifier: methyl methacrylate / butadiene / styrene copolymer (MBS), manufactured by Kaneka Corporation, trade name “M511”
(4) Processing aid ((meth) acrylate polymer):
Product name “Metabrene P-530A”, manufactured by Mitsubishi Rayon Co., Ltd., molecular weight 3.1 million (5) Heat stabilizer: Product name “TVS # 1380” (manufactured by Nitto Kasei Kogyo Co., Ltd.)
(6) Lubricant 1: HW220MP (trade name “Hiwax220MP”, manufactured by Mitsui Chemicals)
(7) Lubricant 2: G70S (trade name “LOXIOL G70S”, manufactured by Emery Oleo Chemicals Japan)
(9) Graphite:
Pyrolytic graphite (trade name “PC99-300M”, manufactured by Ito Graphite Co., Ltd., average particle size 42 μm)
Scale graphite (trade name “CFW18AK”, manufactured by Chuetsu Graphite Co., Ltd., average particle size: 18 μm)

(Resin composition / sheet)
A predetermined amount (% by weight) of each component shown in Table 1 was supplied to a 20 L supermixer (manufactured by Kawata) and mixed by stirring to obtain a resin composition.

The obtained resin composition was supplied to an 8-inch mixing roll kneader (manufactured by Yasuda Seiki Co., Ltd.) and melt-kneaded at a temperature of 185 ° C. to obtain a roll sheet having a thickness of 1 mm.
Next, it is supplied to a hot press molding machine (manufactured by Kobayashi Machine Industry Co., Ltd.), pressed at a temperature of 190 ° C. and 7 MPa, and has a length of 230 mm, a width of 500 mm, and a press sheet (combustion resistant layer or coating layer) having the thickness shown in Table 1. Got.

(Decoration layer)
The following were prepared as a decoration layer of Table 1.
Decorative layer 1: PVC / acrylic mixed single layer film (ML-A, gray, manufactured by American RENOLIT Corporation), thickness: 200 μm, thermal conductivity 0.2 W / m · K, tensile elastic modulus 2,270 MPa,
Decorative layer 2: PVC / acrylic mixed monolayer film (ML-A, gray, manufactured by American RENOLIT Corporation), thickness: 250 μm, thermal conductivity 0.2 W / m · K, tensile elastic modulus 2,270 MPa,
Decorative layer 3: PVC / acrylic mixed monolayer film (ML-A, white, manufactured by American RENOLIT Corporation), thickness: 200 μm, thermal conductivity 0.2 W / m · K, tensile elastic modulus 2,270 MPa,
Decorating layer 4: PVC single layer film, white, thickness: 200 μm, tensile modulus 2,650 MPa.

(Flame resistant sheet)
The decorative layer (front side) and the flame resistant layer or the decorative layer (front side), the flame resistant layer and the coating layer (back side) are overlapped and supplied to a hot press molding machine (manufactured by Kobayashi Machinery Co., Ltd.) Pressurization was performed at 190 ° C. and 7 MPa to obtain a press sheet having a length of 230 mm, a width of 500 mm, and the thickness shown in Table 1.

The obtained flame resistant sheet was evaluated for impact resistance (notched Izod) and vehicle combustion test by the following methods.
<Impact resistance (notched Izod)>
The obtained press sheet was cut to prepare a test piece, which was measured at 23 ° C. in accordance with ASTM D-256.

<Vehicle combustion test>
Ignition: Evaluated in accordance with Article 83 of Section 5 on Fire Countermeasures for Vehicles in “Ministerial Ordinance Establishing Technical Standards on Railways (Ministry of Land, Infrastructure, Transport and Tourism No. 151 December 25, 2001)”.
All surfaces that come into contact with the flame of alcohol are from the decorative layer side.
Judgment criteria:
A: No ignition (equivalent to nonflammability)
○: Ignition time is 70 seconds or more and the fire after ignition is weak (equivalent to extremely flame retardant)
Δ: Ignition over 30 seconds and less than 70 seconds (equivalent to flame retardant)
X: Ignition within 30 seconds

Moreover, the obtained press sheet was set in a vacuum forming machine (manufactured by Fuse Vacuum Co., Ltd.), fixed with a clamp, heated with a heater until the sheet surface temperature reached 170 ° C. to 180 ° C., and then 130 mm long, 300 mm wide, An aluminum mold having a height of 35 mm was protruded and evacuated to bring the sheet into close contact with the mold for evaluation of vacuum forming.
Judgment criteria:
A: Film is not torn and adhesion to the mold is good ○ to A: Film is not torn, but adhesion to the mold is slightly poor ○: Film is not torn, but adhesion to the mold is poor Δ : There is no tearing of the film, but the adhesion to the mold is large. ×: The film is torn or thinned, and the adhesion to the mold is large.

Moreover, the thermal conductivity and the tensile elastic modulus of the decorative layer were evaluated by the following methods.
(Thermal conductivity / thermal conductivity)
A single layer sheet of each of the flame resistant layer and the decorative layer was cut, and a 150 × 100 mm sheet was used as a test piece.
At room temperature, using a thermal conductivity meter (trade name Chemtherm. QTM-D3 (trade name) manufactured by Kyoto Electronics Industry Co., Ltd.) on a standard plate (silicon, quartz, zircon brick) whose thermal conductivity is known. The test pieces were brought into close contact with each other, and a probe was applied to the surface of the test piece (single layer) to measure the conductivity.
Specifically, when the thermal conductivity was 1.4 or more, the sample was brought into close contact with a quartz standard plate, and a probe was placed on the sample and allowed to stand for 2 minutes, followed by measurement. After the measurement, the probe was allowed to stand on an aluminum cooling plate for 2 minutes, and then the sample was brought into close contact with the zircon brick standard plate, and the probe was placed on the plate for 2 minutes to perform measurement.
Subsequently, when measuring another sample, the probe was left on the aluminum cooling plate for 15 minutes, and then the above operation was performed.
The deviation between the thermal conductivity of the standard plate and the measured thermal conductivity of the test piece was plotted, and the thermal conductivity was determined from the intersection of the obtained straight line and deviation = 0.
QTM-D3 (manufactured by Kyoto Electronics Industry) software was used for calculation of thermal conductivity.

The thermal conductivity of the flame resistant layer is
[Thermal conductivity of the flame resistant layer (mW / K)] = [Thickness of the flame resistant layer] × [Thermal conductivity of the flame resistant layer]
Calculated by

(Tensile modulus)
The film used for the decorative layer is laminated to a thickness of 1.5 mm, supplied to a hot press molding machine (manufactured by Toho Machinery Co., Ltd.), pressurized at 190 ° C. and 10 MPa, and a 150 mm × 150 mm press plate Got. The obtained press plate was cut into a dumbbell shape according to ASTM D638, and the tensile modulus was measured at 23 ° C. The test machine was an autograph AGS-J manufactured by Shimadzu Corporation and was equipped with a dedicated extensometer.

  The flame-resistant sheet of the present invention has various functionalities in addition to various fields that require flame resistance, for example, interior materials for vehicles and the like, in particular, interior materials for railway vehicles, automobiles, airplanes, and the like. It can be suitably used as a functional sheet or the like.

Claims (4)

Combustion-resistant sheet composed of a flame-resistant resin composition, a decoration layer, and a coating layer disposed on the opposite side of the decoration layer, a combustion-resistant sheet,
The flame resistant layer is formed of a flame resistant resin composition containing graphite and a thermoplastic resin, and is defined by [thickness of the flame resistant layer] × [thermal conductivity of the flame resistant layer]. The thermal conductivity of the combustible layer] is 3.4 mW / K or more,
The decorative layer includes a vinyl chloride resin and an acrylic resin, and a tensile elastic modulus at 23 ° C. based on ASTM D638 is 2,500 MPa or less,
The coating layer is formed of a thermoplastic resin containing a vinyl chloride resin ,
In the ignition test which makes the flame of alcohol contact from the said decoration layer side, it is nonflammable equivalent which does not ignite, The combustion- resistant sheet | seat characterized by the above-mentioned.   The combustion-resistant sheet according to claim 1, wherein the coating layer includes 1 to 30 parts by weight of an impact modifier with respect to 100 parts by weight of the thermoplastic resin.   The combustion-resistant sheet according to claim 1 or 2, wherein the coating layer contains 1 to 30 parts by weight of a processing aid with respect to 100 parts by weight of the thermoplastic resin. The flame-resistant sheet according to any one of claims 1 to 3, wherein the thermoplastic resin contained in the flame-resistant layer is a vinyl chloride resin.