Flame-retardant polyolefin-based reinforced curtain

Abstract

This flame-retardant polyolefin-based reinforced curtain is provided with: a flame-retardant layer that contains a polyolefin-based resin and a flame retardant; and a reinforcement layer that is composed of polyolefin-based fibers. A recycled resin that is obtained by subjecting this flame-retardant polyolefin-based reinforced curtain to a material recycling treatment has a melt flow rate of 10 g / 10 min to 50 g / 10 min inclusive as determined at 230°C under a load of 2.16 kg.

Description

Flame-retardant polyolefin-based reinforced curtain

[0001] The present disclosure relates to a flame-retardant polyolefin-based reinforced membrane.

[0002] Tarpaulin curtains, which are made of a polyester fiber substrate laminated with a vinyl chloride resin layer, have traditionally been used as large curtains for advertising and construction site protection. However, while tarpaulin curtains have excellent strength and flame retardancy, they contain vinyl chloride resin, which places a heavy burden on the environment when they are disposed of.

[0003] Therefore, a curtain has been proposed in which a polyolefin resin layer containing a flame retardant is laminated on a polyolefin fiber substrate (see, for example, Patent Documents 1 and 2). Such a curtain not only has good properties such as strength and flame retardancy, but is also recyclable, so that disposal burden is small.

[0004] JP 2021-109345 A JP 2023-11232 A

[0005] Meanwhile, with the growing global awareness of a sustainable society, the importance of recycling resin products is also increasing. Therefore, it is desirable that the above-mentioned curtains not only be recyclable, but also that they yield higher quality resins in terms of processability, etc.

[0006] To solve the above problems, various embodiments of a flame-retardant polyolefin-based reinforced membrane are described below. [Embodiment 1] A flame-retardant polyolefin-based reinforced membrane comprises a flame-retardant layer containing a polyolefin resin and a flame retardant, and a reinforcing layer composed of polyolefin fibers. The membrane is recycled to obtain a recycled resin having a melt flow rate of 10 g / 10 min to 50 g / 10 min at 230°C and a load of 2.16 kg. This configuration ensures that the recycled resin is well suited for injection molding and extrusion molding.

[0007] [Aspect 2] The flame-retardant polyolefin-based reinforced film according to aspect 1, wherein the flame-retardant layer contains a bromine-based compound as the flame retardant and a white pigment, and the mass ratios of the materials contained in the flame-retardant layer are 40% to 80% of the polyolefin-based resin, 10% to 20% of the bromine-based compound, and 3% to 20% of the white pigment. This configuration ensures the flame retardancy of the flame-retardant layer and provides excellent concealing properties due to the white pigment. Furthermore, the recycled resin of the reinforced film is more likely to have good physical properties.

[0008] [Embodiment 3] The flame-retardant polyolefin-based reinforced film according to [Embodiment 1] or [Embodiment 2], wherein the flame-retardant layer is composed of a resin composition having a melt flow rate of 8 g / 10 min or more and 30 g / 10 min or less at 230°C and a load of 2.16 kg.

[0009] According to the above-mentioned configuration, the resin composition is highly suitable for T-die extrusion molding. By forming the flame-retardant layer by T-die extrusion molding, it is possible to make the flame-retardant layer thinner, and as a result, it is possible to reduce the weight of the reinforced membrane.

[0010] [Aspect 4] The flame-retardant polyolefin-based reinforced film according to any one of [Aspects 1] to [Aspect 3], wherein the flame-retardant layer has a thickness of 30 μm or more and 200 μm or less. This configuration allows for a reduction in the weight of the reinforced film.

[0011] [Aspect 5] The flame-retardant polyolefin-based reinforced film according to any one of [Aspects 1] to [Aspect 4], wherein the dry heat dimensional change of the polyolefin-based fiber at 150°C is within the range of -5% to -50%. With this configuration, when a flame is ignited, the reinforcing layer undergoes thermal contraction, moving the reinforced film away from the fire source and allowing the remaining flame in the molten part to self-extinguish.

[0012] [Aspect 6] A flame-retardant polyolefin-based reinforced film described in any one of [Aspects 1] to [Aspect 5], wherein the flame-retardant layer is composed of a resin composition having a melt flow rate lower than that of the resin constituting the polyolefin-based fiber.

[0013] [Aspect 7] A flame-retardant polyolefin-based reinforced film described in any one of [Aspects 1] to [Aspect 6], wherein the flame-retardant layer is composed of a resin composition having a flexural modulus smaller than that of the resin constituting the polyolefin-based fiber.

[0014] According to each of the above configurations, the reinforcing function of the reinforcing layer is accurately ensured, and the resin of the flame-retardant layer complements the physical properties of the resin of the reinforcing layer, thereby preventing imbalances in the properties of the recycled resin of the reinforced membrane and obtaining high-quality recycled resin.

[0015] [Aspect 8] The flame-retardant polyolefin-based reinforced film according to any one of [Aspects 1] to [Aspect 7], which comprises one reinforcing layer and two flame-retardant layers sandwiching the reinforcing layer. This configuration provides increased strength compared to a two-layer structure. Furthermore, the increased rigidity of the reinforced film makes it easier to handle during printing processes, etc. Furthermore, the reinforced film is less likely to warp.

[0016] [Aspect 9] The flame-retardant polyolefin-based reinforced film according to any one of [Aspects 1] to [Aspect 7], which comprises one flame-retardant layer and two reinforcing layers sandwiching the flame-retardant layer. This configuration provides increased strength compared to a two-layer structure. Furthermore, the increased rigidity of the reinforced film makes it easier to handle during printing processes, etc. Furthermore, the unique texture of the fabric is reflected in the appearance of the reinforced film, improving the design of the reinforced film. Furthermore, the visibility of wrinkles on the surface of the reinforced film is reduced.

[0017] [Aspect 10] The flame-retardant polyolefin-based reinforced film according to any one of [Aspects 1] to [Aspect 9], having a printable surface, can be used as a decorative material.

[0018] [Aspect 11] The flame-retardant polyolefin-based reinforced film according to [Aspect 10], wherein the polyolefin-based fiber contains a pigment. This configuration enhances the concealing properties of the reinforcing layer, and reduces show-through when printing is applied to the surface of the reinforced film. Therefore, the reinforced film can be used as a decorative material.

[0019] According to the present disclosure, recycled resin with high processability can be obtained.

[0020] Figure 1 shows the cross-sectional structure of a first example of a flame-retardant polyolefin-based reinforced curtain according to one embodiment. Figure 2 shows the cross-sectional structure of a second example of a flame-retardant polyolefin-based reinforced curtain according to one embodiment. Figure 3 shows the cross-sectional structure of a third example of a flame-retardant polyolefin-based reinforced curtain according to one embodiment. Figure 4 shows the cross-sectional structure of a modified example of the flame-retardant polyolefin-based reinforced curtain according to the first example. Figure 5 shows the cross-sectional structure of a modified example of the flame-retardant polyolefin-based reinforced curtain according to the second example. Figure 6 shows the cross-sectional structure of a modified example of the flame-retardant polyolefin-based reinforced curtain according to the third example.

[0021] One embodiment of a flame-retardant polyolefin-based reinforced curtain will be described with reference to the drawings. The flame-retardant polyolefin-based reinforced curtain of this embodiment may be used as a decorative material or as a protective material at construction sites, etc. When used as a decorative material, the flame-retardant polyolefin-based reinforced curtain is printed on the surface and used as an advertising sheet, banner, hanging banner, etc.

[0022] [Layer Structure of Flame-Retardant Polyolefin-Based Reinforced Film] The flame-retardant polyolefin-based reinforced film comprises a flame-retardant layer containing a polyolefin-based resin and a flame retardant, and a reinforcing layer that is a base material made of polyolefin-based fibers.

[0023] 1 shows a first example of the layer structure of a flame-retardant polyolefin-based reinforced curtain 10. The first example of the flame-retardant polyolefin-based reinforced curtain 10, reinforced curtain 10A, comprises one flame-retardant layer 11 and one reinforcing layer 12. The flame-retardant layer 11 is supported by the reinforcing layer 12.

[0024] According to the first example, the reinforced curtain has a two-layer structure, which allows for a lightweight reinforced curtain. Figure 2 shows a second example of the layer structure of a flame-retardant polyolefin-based reinforced curtain 10. The second example of the flame-retardant polyolefin-based reinforced curtain 10, reinforced curtain 10B, comprises two flame-retardant layers 11 and one reinforcing layer 12. The reinforcing layer 12 is sandwiched between the two flame-retardant layers 11.

[0025] According to the second example, the reinforced membrane has a three-layer structure, which increases its strength compared to a two-layer structure. Furthermore, the increased rigidity of the reinforced membrane makes it easier to handle during printing processes, etc. Furthermore, because both sides of the reinforcing layer 12 are covered with the flame-retardant layer 11, the reinforced membrane is less likely to warp due to differences in the materials used on the front and back.

[0026] 3 shows a third example of the layer structure of a flame-retardant polyolefin-based reinforced curtain 10. The third example of the flame-retardant polyolefin-based reinforced curtain 10, reinforced curtain 10C, comprises one flame-retardant layer 11 and two reinforcing layers 12. The flame-retardant layer 11 is sandwiched between the two reinforcing layers 12.

[0027] The third example, like the second example, achieves the benefits of a three-layer structure for the reinforced curtain. Furthermore, since the reinforced curtain has a fiber-based reinforcing layer 12 on its surface, the unique texture of fabric is apparent in its appearance. This also improves the design of the reinforced curtain. Furthermore, the appearance of the reinforced curtain is also reduced, reducing the visibility of wrinkles on its surface.

[0028] In each of the above embodiments, T-die extrusion molding, calendar molding, inflation molding, etc. are used to form the flame-retardant layer 11. When forming the flame-retardant layer 11 thinly, about 30 μm to 200 μm, T-die extrusion molding is suitable because it allows a large degree of freedom in adjusting manufacturing conditions such as the resin discharge amount, lip width, and take-up speed. On the other hand, when forming a flame-retardant layer 11 with a thickness exceeding 200 μm, calendar molding is suitable because it is easy to increase the resin discharge amount and has high productivity.

[0029] Using T-die extrusion molding, the flame-retardant layer 11 can be formed thinly, making it possible to reduce the weight of the flame-retardant polyolefin-based reinforced film 10. As a result, the workability of the reinforced film 10 is improved and the workload is reduced. The thickness of the flame-retardant layer 11 is preferably 30 μm or more and 200 μm or less.

[0030] The flame-retardant layer 11 may be stretched. The stretching ratio is preferably 0.5 to 5. Even if the flame-retardant layer 11 is stretched, residual stress is released when the flame-retardant layer 11 melts upon ignition, causing thermal contraction, which moves the flame-retardant layer 11 away from the fire source, and at the same time, the thermal contraction allows the residual flame in the molten part to self-extinguish.

[0031] The flame-retardant layer 11 and the reinforcing layer 12 may be bonded together using an adhesive, or the flame-retardant layer 11 may be fused to the reinforcing layer 12 without using an adhesive. For laminating the flame-retardant layer 11 and the reinforcing layer 12, it is preferable to use a lamination process such as extrusion lamination or hot-melt lamination.

[0032] The flame-retardant polyolefin-based reinforced curtain 10 may have a printable surface. At least one of the two surfaces of the reinforced curtain 10 is printable. Specifically, the flame-retardant polyolefin-based reinforced curtain 10 has a receiving layer on its surface. The surface of the receiving layer is the outermost printable surface of the reinforced curtain 10.

[0033] Figure 4 shows a first example of a reinforced curtain 10A equipped with a receiving layer 13. The receiving layer 13 is laminated to a flame-retardant layer 11. In the example shown in Figure 4, one of the two surfaces of the reinforced curtain 10A is printable. Figure 5 shows a second example of a reinforced curtain 10B equipped with a receiving layer 13, and Figure 6 shows a third example of a reinforced curtain 10C equipped with a receiving layer 13. In the examples shown in Figures 5 and 6, the reinforced curtains 10B and 10C have receiving layers 13 on both the front and back, and both of the two surfaces of the reinforced curtains 10B and 10C are printable.

[0034] The receiving layer 13 contains an anchoring agent that enhances the adhesion of printing ink to the polyolefin resin. The anchoring agent is, for example, an acrylic or urethane resin. In the reinforced film 10, the surface of the lower layer, such as the flame-retardant layer 11 on which the receiving layer 13 is laminated, may be subjected to surface treatment such as corona discharge treatment, chromic acid oxidation treatment (wet), flame treatment, hot air treatment, ozone plasma irradiation treatment, or easy-adhesion treatment.

[0035] These surface treatments increase the wettability of the coating liquid for forming the receiving layer 13 on the surface of the lower layer, thereby improving the adhesion of the receiving layer 13 to the lower layer. The surface treatment method may be selected depending on the type of the lower layer, but corona discharge treatment and ozone plasma irradiation treatment are preferably used from the viewpoints of the adhesion effect with the receiving layer 13 and the operability of the treatment device.

[0036] Adhesion of the receiving layer 13 to the lower layer may be improved by forming an anchor layer or a primer layer between the lower layer and the receiving layer 13. Materials for the anchor layer and the primer layer may be selected appropriately, but when an aqueous material with high surface tension, such as an alcohol-based material, is used, it is preferable to increase the surface tension to about 50 dyn / cm. When a solvent-based material or a material with low surface tension, such as urethane, is used, coating suitability may be obtained even with a surface tension of about 45 dyn / cm.

[0037] In addition, in the case of applications where the period of use is extremely short, printing may be applied to the surface of the reinforced curtain 10 that does not have the receiving layer 13. Furthermore, in the case where the reinforced curtain 10 is used as a protective material, the reinforced curtain 10 does not need to have the receiving layer 13, and printing on the reinforced curtain 10 does not need to be performed.

[0038] [Characteristics of the Flame-Retardant Polyolefin-Based Reinforced Film] The melt flow rate (MFR) of the recycled resin obtained by subjecting the entire flame-retardant polyolefin-based reinforced film 10 to material recycling is 10 g / 10 min or more and 50 g / 10 min or less.

[0039] In the material recycling process, the reinforced film 10 is crushed and melted, then molded into pellets or the like to produce recycled resin. The MFR of the recycled resin is measured in accordance with JIS K7210-1:2014 (ISO 1133-1:2011). The temperature conditions are 230°C and the load is 2.16 kg. Having an MFR of the recycled resin within the above range ensures that the recycled resin is well suited to versatile processing methods such as injection molding and extrusion molding. Therefore, since these processing methods can be used to process the recycled resin, the flexibility of the recycled resin's applications is also increased.

[0040] The MFR of the recycled resin can be controlled by adjusting the MFR of the constituent layers of the flame-retardant polyolefin-based reinforced film 10. Since the proportion of the receiving layer 13 in the flame-retardant polyolefin-based reinforced film 10 is at most about 2% by mass, the effect of the receiving layer 13 on the MFR of the recycled resin is extremely small.

[0041] The constituent layers of the flame-retardant polyolefin-based reinforced film 10 are described in detail below. [Flame-Retardant Layer] The flame-retardant layer 11 contains a polyolefin-based resin and a flame retardant. The flame-retardant layer 11 preferably further contains a white pigment and various additives. Details of each material and the physical properties of the flame-retardant layer 11 are described below.

[0042] (Polyolefin Resin) Examples of polyolefin resins include syndiotactic polypropylene, isotactic polypropylene, atactic polypropylene, homopolypropylene, random polypropylene, block polypropylene, ethylene-α-olefin copolymer, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-methyl methacrylic acid copolymer, ethylene-methyl methacrylic acid ester copolymer, ethylene-ethyl acrylic acid copolymer, ethylene-ethyl acrylic acid ester copolymer, etc. The polyolefin resin contained in the flame-retardant layer 11 may be one type of resin or may contain two or more types of resins.

[0043] Polyolefin resins may be produced by radical polymerization or ionic polymerization. Polyethylene resins produced by radical polymerization include ethylene homopolymers and copolymers of ethylene and monomers capable of radical polymerization with the ethylene.

[0044] As the polyolefin resin, polypropylene resin is preferably used. When the flame-retardant layer 11 is formed by calendar molding, the temperature for laminating the reinforcing layer 12 is lowered, so the proportion of polyethylene resin in the flame-retardant layer 11 may be increased to increase the adhesive strength of the flame-retardant layer 11 to the reinforcing layer 12 during lamination.

[0045] The polyolefin resin may contain a biomass resin. Examples of biomass resins are biomass polyethylene resin and biomass polypropylene resin. Biomass resin is a resin produced using renewable biological resources such as plants as raw materials. For example, biomass resin is produced by polymerizing plant-derived monomers. A known method may be used to produce the biomass resin. By including a biomass resin in the polyolefin resin, a flame-retardant polyolefin-based reinforced film 10 that contributes to carbon neutrality can be realized.

[0046] The polyolefin resin may contain both a fossil fuel-derived resin and a biomass resin. For example, the polyolefin resin may contain a fossil fuel-derived polypropylene resin and a biomass polyethylene resin. The proportion of the biomass resin in the polyolefin resin is preferably less than 50 mass %, for example. This configuration allows the flame-retardant layer 11 to maintain its properties while contributing to carbon neutrality.

[0047] By measuring the radioactive carbon (C14) in polyolefin resins, it is possible to calculate the biomass ratio, which is the proportion of biologically derived materials in the polyolefin resin. Since carbon dioxide in the atmosphere contains a certain proportion of C14 (105.5 pMC), the C14 concentration in plants that grow by absorbing carbon dioxide from the atmosphere is also about 105.5 pMC. On the other hand, fossil fuels contain almost no C14.

[0048] Therefore, the biomass ratio can be calculated by determining the proportion of C14 carbon atoms contained in the total carbon atoms of the polyolefin resin. The biomass ratio Pbio (%) can be calculated using the following formula (1), where Pc (pMC) is the C14 concentration in the polyolefin resin: Pbio = (Pc / 105.5) × 100 (1)

[0049] When the entire polyolefin resin contained in the flame-retardant layer 11 is a resin derived from a living organism, the biomass content is theoretically 100%. When the entire polyolefin resin is a resin derived from a fossil fuel, the biomass content is theoretically 0%. Based on this, it is possible to confirm the presence of a biomass resin in the polyolefin resin by measuring the C14 content in the resin composition constituting the flame-retardant layer 11.

[0050] (Flame Retardant) It is preferable to use a combination of a bromine-based compound and an inorganic compound as a flame retardant. Bromine-based compounds include drip-type and non-drip-type flame retardants. Drip-type compounds suppress combustion by falling droplets. Non-drip-type compounds act on the gas phase, suppressing combustion by trapping OH radicals and diluting and blocking oxygen by generating non-flammable gases. When the flame-retardant layer 11 is formed at high temperatures, such as when the flame-retardant layer 11 is formed by T-die extrusion molding, drip-type flame retardants decompose, so non-drip-type flame retardants are preferably used. Furthermore, when pelletized recycled resin is produced using extrusion molding in a recycling process, drip-type flame retardants also decompose. Therefore, using non-drip-type flame retardants results in higher-quality recycled resin.

[0051] Examples of inorganic compounds include antimony oxide compounds such as antimony trioxide and antimony pentoxide, hydrated metal compounds such as magnesium hydroxide and aluminum hydroxide, and zinc borate. In particular, it is preferable to use an antimony oxide compound. By using an antimony oxide compound in combination with a bromine compound, a heavy non-flammable gas containing antimony is generated upon ignition, thereby synergistically enhancing the oxygen dilution effect and the oxygen blocking effect.

[0052] To ensure flame retardancy, the mass ratio of the flame retardant contained in the flame-retardant layer 11 is preferably 7 or more, with the polyolefin resin taken as 100. In addition, to prevent the MFR of the resin composition used to form the flame-retardant layer 11 from becoming too high, the mass ratio of the flame retardant contained in the flame-retardant layer 11 is preferably 30 or less, with the polyolefin resin taken as 100.

[0053] (White Pigment) When the flame-retardant polyolefin-based reinforced film 10 is used as a decorative material, it is particularly important to prevent color changes such as yellowing due to ultraviolet rays.

[0054] Furthermore, as described above, when the flame-retardant layer 11 is formed by T-die extrusion molding, the flame-retardant layer 11 becomes thin, and therefore the color of the reinforcing layer 12 superimposed on the flame-retardant layer 11 becomes more visible in the reinforced film 10 of the first and second examples. Therefore, it is preferable that the light-shielding property and whiteness of the flame-retardant layer 11 be enhanced.

[0055] Therefore, it is preferable that the flame-retardant layer 11 contains a white pigment for the purpose of increasing the whiteness of the flame-retardant layer 11 and blocking light. Examples of white pigments include titanium oxide and barium sulfate. Titanium oxide is particularly suitable because it has a small particle size and a high hiding effect.

[0056] Titanium oxide primarily used for industrial purposes comes in two types: rutile and anatase. Of these, rutile, which has a higher refractive index, is preferred. Specifically, the refractive index of rutile titanium oxide (rutile) is 2.72, while the refractive index of anatase titanium oxide (anatase) is 2.52. The refractive index is the primary factor determining the optical properties of inorganic pigments; the higher the refractive index, the greater the surface reflection, which in turn increases the light scattering in the resin, and therefore the greater the hiding power. Therefore, using titanium oxide with a higher refractive index can reduce the yellowing of the resin due to ultraviolet rays.

[0057] Furthermore, titanium oxide strongly absorbs light with wavelengths shorter than 400 nm, but does not absorb visible light, and therefore exhibits effects similar to those of light stabilizers and ultraviolet absorbers. Therefore, the inclusion of titanium oxide allows the content of these additives to be reduced.

[0058] Titanium oxide also has photocatalytic properties, exerting strong oxidizing power on its surface when exposed to light. This property is used industrially to decompose difficult-to-decompose substances, but if its oxidizing power is exerted in resin or on the surface layer of a flame-retardant polyolefin-based reinforced film 10, it may cause deterioration of the resin or the quality of the printed surface. Therefore, it is preferable to subject titanium oxide to a surface treatment to suppress its oxidizing power before use. Examples of surface treatment agents and dispersants include silica, aluminum hydroxide, dimethicone, cyclopentasiloxane, triethoxycaprylylsilane, hydrogen dimethicone, isostearic acid, stearic acid, alumina, and sodium polyacrylate.

[0059] Inorganic fillers have the effect of enhancing light-shielding properties, and antimony oxide compounds, magnesium hydroxide, aluminum hydroxide, and the like used as flame retardants also have the effect of improving light-shielding properties and whiteness.

[0060] In order to accurately obtain the light-shielding and whitening effects, the weight ratio of the functional component for light-shielding and whitening contained in the flame-retardant layer 11 is preferably 10 or more relative to the polyolefin resin (100). Furthermore, the weight ratio of the functional component contained in the flame-retardant layer 11 is preferably 30 or less relative to the polyolefin resin (100). If the weight ratio of the functional component is 30 or less, the inorganic filler component does not become too high, thereby suppressing the progression of resin degradation due to shear heat during the manufacturing process of the flame-retardant layer 11. Furthermore, the specific gravity does not become too high, thereby suppressing a decrease in processability for T-die extrusion molding.

[0061] (Additives) Additives have functions such as improving processing stability, weather resistance, strength, etc. Specific examples of additives include lubricants, antioxidants, light stabilizers, antistatic agents, and ultraviolet absorbers.

[0062] When a large amount of a hydrated metal compound is contained as a flame retardant, resin deterioration due to shear heat is likely to progress during the manufacturing process of the flame-retardant layer 11. Therefore, it is preferable to add a lubricant. Adding a lubricant to the resin composition used to form the flame-retardant layer 11 can reduce friction between the resin and the molding machine and friction between resin particles. For example, hydrocarbon-based, fatty acid-based, aliphatic alcohol-based, aliphatic amide-based, metal soap-based, or other lubricants can be used. It is preferable to use a combination of multiple lubricants, taking into account the balance between external and internal lubrication.

[0063] In addition, it is preferable to add an antioxidant to suppress resin deterioration due to shear heat and to improve weather resistance for outdoor use. Antioxidants include primary antioxidants as radical scavengers and secondary antioxidants as peroxide decomposers.

[0064] Phenol-based antioxidants are commonly used as primary antioxidants. Phenolic antioxidants have the effect of stabilizing alkoxy radicals generated from radicals generated by ultraviolet light or thermal energy and oxygen. There are three types of phenolic antioxidants, hindered type, semi-hindered type, and less hindered type, which differ in chemical structure, and these differ in the number of radicals captured and the reaction rate. In general, polyolefin resins are relatively stable resins and undergo oxidation reactions slowly, so hindered-type antioxidants that act slowly are effective. Representative commercially available phenolic antioxidants include the Irganox series manufactured by BASF and the AO series manufactured by ADEKA.

[0065] Sulfur-based and phosphorus-based antioxidants are used as secondary antioxidants. These antioxidants decompose the hydroperoxide (ROOH) produced as a reaction product of radical scavenging by the phenol-based antioxidant into stable substances, thereby suppressing the chain reaction of radical generation from the hydroperoxide, which leads to the progression of oxidation.

[0066] However, since sulfur-based antioxidants generate odors at high temperatures and are difficult to color, it is preferable to use phosphorus-based antioxidants when manufacturing a white reinforced film 10. Representative commercially available phosphorus-based antioxidants include Irgafos 168 manufactured by BASF and 2112 in the PEP series manufactured by ADEKA.

[0067] It is preferable to add an ultraviolet absorber to the flame-retardant layer 11 in order to prevent resin deterioration due to exposure to ultraviolet light. Benzotriazole-based or benzophenone-based ultraviolet absorbers are used as the ultraviolet absorber. These ultraviolet absorbers absorb ultraviolet light in the wavelength range of about 320 nm to 350 nm, which is the wavelength range to which resins are most susceptible.

[0068] Furthermore, higher light stability can be achieved by using hindered amine light stabilizers (HALS) in combination with an ultraviolet absorber. HALS have the effect of capturing radicals generated by ultraviolet light, and exhibit the effects of preventing discoloration and maintaining gloss. However, when used together with a bromine-based compound, which is a flame retardant, a small amount of acidic substances are generated in the resin composition due to the action of the bromine-based compound, and if the HALS is alkaline, neutralization occurs, antagonizing the reaction. Therefore, it is preferable to use NOR-type HALS, which is less likely to form salts with acidic substances.

[0069] Representative commercially available ultraviolet absorbers include the Tinuvin series and Uvinul series manufactured by BASF. The Tinuvin series contains HALS. Representative commercially available HALS products include the LA series manufactured by ADEKA.

[0070] (Mixing ratio of materials) The mass proportions of the materials contained in the flame-retardant layer 11 are preferably 40% or more and 80% or less of polyolefin-based resin, 10% or more and 20% or less of bromine-based compound, and 3% or more and 20% or less of white pigment, relative to the total mass of the flame-retardant layer 11.

[0071] In order to obtain good physical properties from the recycled resin, the proportion of polyolefin resin in the flame-retardant layer 11 is preferably 50% by mass or more. However, even if the proportion of polyolefin resin is less than 50% by mass, the recycled resin can still be used as a material for molded products by injection molding or the like.

[0072] (MFR) The resin composition used to form the flame-retardant layer 11 preferably has an MFR at 230° C. under a load of 2.16 kg of 8 g / 10 min or more and 30 g / 10 min or less.

[0073] As described above, it is preferable to use T-die extrusion molding to reduce the weight of the flame-retardant polyolefin-based reinforced film 10. If the resin composition has an MFR of 8 g / 10 min or more and 30 g / 10 min or less, it is highly suitable for T-die extrusion molding.

[0074] If the MFR of the resin composition is low, around 0.5 g / 10 min to 7 g / 10 min, the resin's fluidity is too low, making it difficult to increase the extrusion rate in the extruder, resulting in low productivity. While it is possible to increase the fluidity in the extrusion machine by increasing the resin temperature, significant improvements in fluidity are difficult, and increasing the extrusion rate causes a pulsating phenomenon known as draw resonance, making stable production difficult. Further increasing the resin temperature improves draw resonance, but if the resin temperature is too high, problems such as deterioration due to the resin's thermal history, melting or thermal shrinkage of the reinforcing layer 12 during lamination of the flame-retardant layer 11 to the reinforcing layer 12, and blocking due to insufficient cooling after the recovery process of the manufactured film can occur. If the MFR of the resin composition is 8 g / 10 min or higher, the occurrence of these problems can be suppressed.

[0075] On the other hand, if the MFR of the resin composition exceeds 30 g / 10 min, the fluidity is significantly improved, but in order to increase the MFR to more than 30 g / 10 min, a resin with a low average molecular weight must be used. If a resin with a low average molecular weight is used, holes are likely to be formed during film formation of the flame-retardant layer 11, significantly reducing moldability. If the MFR of the resin composition is 30 g / 10 min or less, the occurrence of such problems can be suppressed.

[0076] Furthermore, if the MFR of the resin composition is 8 g / 10 min or more and 30 g / 10 min or less, it is easy to control the MFR of the recycled resin of the flame-retardant polyolefin-based reinforced film 10 to 10 g / 10 min or more and 50 g / 10 min or less.

[0077] In order to obtain a desired MFR for a resin composition, it is preferable to use a polyolefin resin having an MFR that is about 5 g / 10 min to 10 g / 10 min smaller than the desired MFR. This makes it easy to control the MFR of the resin composition to a desired value of 30 g / 10 min or less, even if the MFR increases due to the inclusion of a flame retardant.

[0078] [Reinforcing Layer] (Polyolefin Fiber) The material of the polyolefin fiber constituting the reinforcing layer 12 may be polyethylene or polypropylene. As an example, the structure of polypropylene fiber will be described below.

[0079] Known resins are used as the polypropylene resin constituting the fibers. The polypropylene resin may be a polymer obtained from a monomer containing propylene as the main component. For example, the polypropylene resin may be a homopolymer of propylene, or a copolymer of propylene and one or more other comonomers. Examples of comonomers include olefin hydrocarbons such as ethylene and 1-butene.

[0080] Specific examples of the copolymer include propylene-ethylene random copolymers, propylene-ethylene-α-olefin random copolymers such as propylene-ethylene-1-butene copolymers, and propylene-α-olefin random copolymers such as propylene-1-butene copolymers, propylene-1-pentene copolymers, propylene-1-hexene copolymers, and propylene-1-octene copolymers. The α-olefin used in the copolymerization preferably has 4 to 10 carbon atoms.

[0081] The polypropylene resin constituting the fibers may be a single type of resin or a mixture of two or more types of resins. For example, the polypropylene resin may be a mixture of propylene homopolymers with different average molecular weights, or a mixture of a propylene homopolymer and the random copolymers exemplified above. In one example, the polypropylene resin may be a mixture of a propylene homopolymer and a low-crystalline or amorphous propylene-ethylene random copolymer.

[0082] When a homopolymer polypropylene resin is used, an isotactic polymer is usually used, but it is also acceptable to use a syndiotactic polymer or an atactic polymer, or for the resin constituting the fiber to contain these polymers.

[0083] When the flame-retardant polyolefin-based reinforced film 10 is used as a decorative material and printing is applied to the surface of the reinforced film 10, a concealing pigment may be added to the resin of the fiber material to prevent show-through. Examples of pigments include black pigment, white pigment, opaque pigment, etc. For example, when a black pigment is used, adding approximately 3% by mass of the black pigment to the polyolefin-based resin provides sufficient light-blocking performance in the reinforcing layer 12 made of fibers formed from this resin material.

[0084] The dry heat dimensional change rate of the polyolefin fiber at 150°C is preferably within the range of -5% to -50%. The dry heat dimensional change rate is measured in accordance with JIS L1013 Method B. The heat treatment time is 30 minutes. If the dry heat dimensional change rate is within the above range, when a flame is ignited, the polyolefin fiber undergoes thermal contraction, which moves the reinforcing layer 12 away from the fire source and simultaneously enables self-extinguishing of any remaining flames in the molten zone.

[0085] (Method of Manufacturing Fiber) The polyolefin-based fiber constituting the reinforcing layer 12 may be a multifilament or a flat yarn.

[0086] Multifilaments are produced using a melt spinning method. Specifically, molten resin is extruded from a spinning nozzle and cooled to obtain undrawn yarns. The undrawn yarns are then reheated and drawn to obtain drawn yarns. Multifilaments are made up of these drawn yarns. The drawing ratio is about 3 to 10 times.

[0087] Flat yarns can be obtained by forming a molten resin into a film by a method such as T-die extrusion or inflation molding, cutting the film into strips, and stretching the film. The stretching ratio is preferably 3 to 15 times, more preferably 5 to 10 times. This ensures sufficient strength. To prevent uneven stretching, the stretching is preferably carried out in multiple stages.

[0088] Split yarn can be obtained by splitting flat yarn into small pieces. Flat yarn is a thick, flat, strip-like yarn, but by splitting flat yarn, thin yarns like multifilament can be obtained.

[0089] The thickness of the polyolefin fiber is not particularly limited, but when multifilament is used, if the yarn is too thin, it will melt due to frictional heat during the weaving process, resulting in reduced productivity. Therefore, the thickness of the polyolefin fiber is preferably 100 denier or more, and the filament count of the multifilament is preferably 48 or more. The polyolefin fiber may also be FTY (filament twisted yarn) or DTY (draw textured yarn).

[0090] The resin constituting the polyolefin fiber of the reinforcing layer 12 preferably has an MFR of 20 g / 10 min or more and 50 g / 10 min or less at 230°C and a load of 2.16 kg. Generally, the resin constituting the polyolefin fiber has an MFR that corresponds to the fiber manufacturing method, the fiber application, and the desired function. For example, some fibers are made of resins with an MFR of around 5 g / 10 min, while others are made of resins with an MFR of more than 50 g / 10 min. By varying the physical properties of the resin, it is possible to impart various functions to the polyolefin fiber, and substrates made of polyolefin fibers are used for a variety of applications.

[0091] As an example, Table 1 shows the properties of polyolefin-based fibers according to their applications. The properties of the yarn for each application are described in the book "Easy Basic Knowledge of Industrial Fibers" published by Nikkan Kogyo Shimbun.

[0092]

[0093] As described above, the characteristics of polyolefin-based fibers differ depending on the physical properties of the resin. It is preferable that the polyolefin-based fibers of the reinforcing layer 12 be made of a resin that can enhance the reinforcing function of the reinforcing layer 12, in other words, a resin that can increase the strength of the fibers. Strength can be improved by using a resin with a large average molecular weight, i.e., a resin with a small MFR. On the other hand, if the MFR is too small, moldability decreases, resulting in a decrease in yarn productivity. From this perspective, it is preferable that the fibers of the reinforcing layer 12 be made of a resin with an MFR of 20 g / 10 min or more and 50 g / 10 min or less.

[0094] Resins having an MFR in this range are suitable for producing yarns by melt spinning, and therefore the polyolefin fibers constituting the reinforcing layer 12 are preferably multifilament.

[0095] Furthermore, if the MFR of the resin of the reinforcing layer 12 is within the above range, it is easy to control the MFR of the recycled resin of the flame-retardant polyolefin-based reinforced film 10 to 10 g / 10 min or more and 50 g / 10 min or less.

[0096] (Method of Manufacturing Reinforcing Layer) The reinforcing layer 12 may be a woven fabric, a knitted fabric, or a nonwoven fabric.

[0097] Woven fabrics have a structure in which warp threads and weft threads cross at right angles, and are manufactured by interlacing the weft threads with the parallel warp threads according to a certain rule. The weaving structure of a woven fabric, i.e., the interlacing pattern of the warp and weft threads, includes plain weave, twill weave, satin weave, imitation weave, pongee weave, leno weave, etc.

[0098] The strength and texture of the woven fabric vary depending on the number of warp and weft threads and the structure, but are not particularly limited in this embodiment. The warp and weft thread densities are, for example, from 5 threads / 2.54 cm to 40 threads / 2.54 cm, and preferably from 10 threads / 2.54 cm to 30 threads / 2.54 cm. An example of a commercially available woven fabric is Tarpee Cloth (manufactured by Hagiwara Industries Co., Ltd.).

[0099] Examples of knitted fabrics include raschel knit, tricot knit, and Milanese knit. The reinforcing layer 12 may also be a mesh nonwoven fabric. A mesh nonwoven fabric has a structure in which layers of parallel flat yarns are stacked so that the parallel directions are perpendicular to each other, and these layers are heat-fused. Representative commercially available examples of mesh nonwoven fabrics include Warif (registered trademark, manufactured by JX ANCI), CLAF (registered trademark, manufactured by JX ANCI), and Sof (manufactured by Sekisui Film).

[0100] [Differences in physical properties between flame-retardant layer and reinforcing layer] In the recycled resin of flame-retardant polyolefin-based reinforced film 10, the resin of the flame-retardant layer 11 and the resin of the reinforcing layer 12 are kneaded together.Therefore, in order to obtain a recycled resin with good properties, it is necessary to consider the balance of the physical properties of the resins of the flame-retardant layer 11 and the reinforcing layer 12.

[0101] Specifically, from the viewpoint of strength and rigidity, it is preferable to use polypropylene resin, which is a homopolymer with an isotactic structure, for the fibers of the reinforcing layer 12, and the characteristics of the homopolymer are reflected in the resin obtained by recycling such reinforcing layer 12. As a result, the recycled resin of the reinforcing layer 12 is characterized by high flexural modulus and hardness, but low impact strength.

[0102] Therefore, it is preferable to use a polypropylene resin, which is a random polymer, as the resin for the flame-retardant layer 11. A polypropylene resin, which is a random polymer, has a structure in which a small amount of comonomer such as ethylene is randomly incorporated into a propylene chain. This breaks down the regular propylene chain, reducing the crystallinity of the polymer, but it also softens the polymer and makes it sticky, improving impact resistance.

[0103] Therefore, by using a random polymer as the resin for the flame-retardant layer 11, the impact strength is supplemented by the recycled resin of the flame-retardant polyolefin-based reinforced film 10, and good impact resistance is obtained.

[0104] Thus, in order to obtain a recycled resin with good properties, it is preferable to use a resin that is softer, more stretchable, and more viscous as the resin for the flame-retardant layer 11 than the resin for the reinforcing layer 12. Specifically, the resin composition constituting the flame-retardant layer 11 has a lower flexural modulus, a larger nominal tensile strain at break, and a larger Charpy impact strength than the resin constituting the polyolefin fibers of the reinforcing layer 12. Furthermore, the MFR of the resin composition of the flame-retardant layer 11 is smaller than the MFR of the resin for the reinforcing layer 12.

[0105] This allows the reinforcement layer 12 to adequately reinforce the reinforced membrane 10 while minimizing the bias in the properties of the recycled resin, resulting in a recycled resin that can be used in a wide range of applications. In other words, good properties can be obtained for both the reinforced membrane 10 and the recycled resin.

[0106] [Examples] The above-mentioned flame-retardant polyolefin-based reinforced film will be explained using specific examples and comparative examples.

[0107] (Configuration of the flame-retardant polyolefin-based reinforced film of Example 1) <Production method> The following materials were mixed to produce a resin composition used to form the flame-retardant layer. Polyolefin-based resin: 100 parts by mass of polypropylene resin (random polymer); Flame retardant: 11 to 21 parts by mass of bromine compound; 3 to 7 parts by mass of antimony oxide compound; White pigment: 10 to 11 parts by mass of titanium oxide; Additives: 0 to 2 parts by mass of antioxidant, HALS, UVA, lubricant, etc.

[0108] A flame-retardant layer made of the resin composition was laminated onto a reinforcing layer by T-die extrusion molding and lamination to obtain a laminate in which the reinforcing layer was sandwiched between two flame-retardant layers. The flame-retardant layer had a thickness of 80 μm. The reinforcing layer was a plain-woven fabric made of multifilament yarn. The multifilament yarn was a polypropylene fiber made of an isotactic homopolymer.

[0109] Both surfaces of the laminate were subjected to a corona discharge treatment to improve the surface wettability to about 48 dyn / cm. A urethane anchoring agent was applied to the corona discharge-treated surface by gravure printing, and the coating was dried and solidified to form a receiving layer. The coating had a solid content of the anchoring agent of 4.0 g / m. ２ In this way, a flame-retardant polyolefin-based reinforced membrane of Example 1 was obtained.

[0110] <Dry heat dimensional change rate of fibers in reinforcing layer> The shrinkage rate upon heating of the polypropylene fibers constituting the reinforcing layer of Example 1 was measured in accordance with JIS L1013 Method B. The results are shown in Table 2. In condition 1, the treatment temperature was 120°C and the treatment time was 30 minutes. In condition 2, the treatment temperature was 150°C and the treatment time was 30 minutes.

[0111]

[0112] It was confirmed that polypropylene fibers shrink when heated, as shown in Table 2. By using a reinforcing layer made of such fibers, when a flame-retardant polyolefin-based reinforced film catches fire, the film shrinks thermally, moving away from the fire source, and at the same time, the remaining flame in the molten area self-extinguishes.

[0113] <Comparison of physical properties between flame-retardant layer and reinforcing layer> The resin composition used to form the flame-retardant layer in Example 1 and the resin obtained by recycling the reinforcing layer were each measured for MFR, tensile yield stress, tensile stress at break, nominal tensile strain at break, flexural strength, flexural modulus, and Charpy impact strength.

[0114] MFR was measured in accordance with ISO 1133 at a temperature of 230°C and a load of 2.16 kg. Tensile yield stress, tensile stress at break, and nominal tensile strain at break were measured in accordance with ISO 527-1 at a pulling rate of 50 mm / min. Flexural strength and flexural modulus were measured in accordance with ISO 178. Charpy impact strength was measured using a notched test piece in accordance with ISO 179. The measurement results for each physical property are shown in Table 3.

[0115]

[0116] As shown in Table 3, the resin composition of the flame-retardant layer has a lower MFR and a lower flexural modulus than the recycled resin of the reinforcing layer, which means it is softer. Furthermore, the resin composition of the flame-retardant layer has a higher nominal tensile break strain (435% or more) than the recycled resin of the reinforcing layer, which means it is more stretchable. Furthermore, the resin composition of the flame-retardant layer has a higher Charpy impact strength than the recycled resin of the reinforcing layer, which means it is tougher.

[0117] (Physical Properties of Flame-Retardant Polyolefin-Based Reinforced Film) The mass, thickness, tensile strength, and tear strength of the flame-retardant polyolefin-based reinforced films of Example 1 and Comparative Example were measured. For the flame-retardant polyolefin-based reinforced film of Comparative Example, the flame-retardant layer was produced by calendar molding. Because calendar molding places importance on the viscosity of the resin during molding, the flame-retardant layer of Comparative Example was formed using a resin composition with a lower MFR than that of Example 1.

[0118] The mass was measured according to JIS L1096 8.3.2. The thickness was measured according to JIS L1096 8.4. The tensile strength was measured according to JIS L1096 8.14.1 Method A (strip method) with a test piece width of 30 mm. The tear strength was measured according to JIS L1096 8.17.4 Method D (pendulum method). The measurement results for each physical property are shown in Table 4.

[0119]

[0120] As shown in Table 4, the flame-retardant polyolefin-based reinforced film of Example 1 is thinner than the comparative example, with a mass of 50% or less. This is the result of forming a thinner flame-retardant layer using extrusion molding. As shown in Table 3, the MFR of the resin composition of the flame-retardant layer is 8 g / 10 min or more and 30 g / 10 min or less, making it possible to use this molding method and achieve this thickness. In Example 1, the tensile strength is slightly lower than that of the comparative example as the thickness decreases, but sufficient strength is still maintained for practical use.

[0121] (Flame Retardancy Evaluation) The flame-retardant polyolefin-based reinforced film of Example 1 was subjected to a flame retardancy test using the 45° microburner method specified in the flame retardancy performance test method of the Ministry of Internal Affairs and Communications Ordinance. For pretreatment, the reinforced film was immersed in 50°C warm water for 30 minutes. The test results are shown in Table 5. Note that this test method requires evaluation of three samples for the 1-minute heating test and two samples for the 3-second heating test after flame ignition. Samples 1 to 3 used in the 1-minute heating test and Samples 1 and 2 used in the 3-second heating test after flame ignition are different samples.

[0122]

[0123] As shown in Table 5, it was confirmed that the flame-retardant polyolefin-based reinforced membrane of Example 1 exhibited good flame retardancy. Therefore, it was confirmed that the flame-retardant polyolefin-based reinforced membrane of Example 1 had sufficient flame retardancy.

[0124] (Evaluation of Printability) A pattern was printed on the surface of the receiving layer of the flame-retardant polyolefin-based reinforced film of Example 1 using a UV inkjet printer. Thereafter, evaluations of coating adhesion and rub fastness were carried out to evaluate printability. The coating adhesion was evaluated according to JIS K5600-5-6 (cross-cut method) with a cut interval of 2 mm. The rub fastness was evaluated in accordance with JIS L0849 by observing the color staining of the rubbing cloth and the appearance of the rubbed object. The evaluation results are shown in Table 6.

[0125]

[0126] As shown in Table 6, the coating adhesion evaluation was rated as Class 1, meaning that small peeling of the printed coating was observed at the intersections of the cuts, but the affected area in the cross-cut region was less than 5%. Furthermore, the evaluation of friction fastness using a staining gray scale confirmed a rub fastness of about Grade 4-5. Therefore, it was confirmed that the flame-retardant polyolefin-based reinforced film of Example 1 has good printability and the printed coating is less likely to peel off.

[0127] (Recycling Suitability Evaluation) <Physical Properties of Recycled Resin> A pattern was printed on the surface of the receiving layer of the flame-retardant polyolefin-based reinforced film of Example 1 using a UV inkjet printer. This reinforced film was subjected to material recycling to obtain recycled resin. The following three methods, A to C, were used for the material recycling process, and recycled resin was obtained by each method.

[0128] Method A: Using a waste plastic compactor (Mr. Meino), compacted flake material was produced from reinforced film, and this compacted flake material was pelletized using a single-screw extruder to obtain recycled resin. The processing temperature of the compactor was 200°C. The processing temperature of the single-screw extruder was also 200°C, and impurities were removed using an 80-mesh sieve.

[0129] Method B: Using an integrated recycling processing machine (manufactured by Ichioku), pelletized recycled resin was obtained from the reinforced film. The processing temperature was 200°C, and impurities were removed using a 200 mesh. Method C: Using a waste plastic volume reduction machine (manufactured by Meino), volume-reduced flake material was generated from the reinforced film, and this volume-reduced flake material was sorted through a sieve to homogenize the shape, resulting in recycled resin. The processing temperature of the volume reduction machine was 200°C. A mesh with 5 mm openings was used as the sieve.

[0130] The recycled resins obtained by each method were measured for MFR, tensile stress at yield, tensile stress at break, nominal tensile strain at break, flexural strength, flexural modulus, and Charpy impact strength. MFR was measured in accordance with ISO 1133 at a temperature of 230°C and a load of 2.16 kg. Tensile stress at yield, tensile stress at break, and nominal tensile strain at break were measured in accordance with ISO 527-1 at a pulling rate of 50 mm / min. Flexural strength and flexural modulus were measured in accordance with ISO 178. Charpy impact strength was measured using notched test specimens in accordance with ISO 179. The measurement results for each physical property are shown in Table 7.

[0131]

[0132] As shown in Table 7, regardless of whether methods A, B, or C were used, the MFR of the recycled resin ranged from 21 g / 10 min to 24 g / 10 min, values ​​suitable for injection molding and extrusion molding. Furthermore, compared to Table 3, the MFR and flexural modulus were higher than those of the resin composition of the flame-retardant layer and lower than those of the recycled resin of the reinforcing layer. The nominal tensile strain at break was 435% or higher, and the Charpy impact strength was lower than that of the resin composition of the flame-retardant layer and higher than that of the recycled resin of the reinforcing layer. Therefore, the physical properties of the resin of the reinforcing layer were complemented by those of the resin of the flame-retardant layer, resulting in a recycled resin with good softness, elongation, and toughness.

[0133] <Processability of Recycled Resins> Two types of molding tests were carried out on each of the recycled resins obtained by the above methods A to C.

[0134] [Single-layer film formation test using a small T-die] Recycled resin was molded into a sheet using the following equipment and manufacturing conditions: Equipment used: T-die extrusion molding machine (manufactured by Plastics Engineering Research Institute) Die width: 150 mm Molding temperature: 230°C Take-up speed: 2.9 m / min Film thickness: 80 μm Pellet pretreatment: Hot air dried at 80°C for 8 hours or more to remove moisture Pellets moisture content: 349.00 ppm (Karl Fischer method, heating temperature: 220°C, end-point drift value: 0.1 μg / s or less) The test results showed that very clean sheets could be produced for each recycled resin.

[0135] [Extrusion Lamination Test Using a Small T-Die] Equipment: T-Die Extrusion Sandwich Lamination Machine; Die Width: 400 mm; Molding Temperature: 250°C; Take-up Speed: 10 m / min, 20 m / min, 25 m / min, 30 m / min, 40 m / min; White Fabric: Polypropylene Woven Fabric; Film Thickness: 80 μm; Pellet Pretreatment: Hot Air Drying at 80°C for 8 hours or More to Remove Moisture; Pellet Moisture Content: 349.00 ppm (Karl Fischer Method, Heating Temperature: 220°C, End-Point Drift: 0.1 μg / s or Less). The test results showed that excellent sheets could be produced with each recycled resin, from a low take-up speed of 10 m / min to a high speed of 40 m / min. These results confirmed that the flame-retardant polyolefin-based reinforced film of Example 1 can be used to produce recycled resins with high suitability for sheet processing.

[0136] (Configuration of the Flame-Retardant Polyolefin-Based Reinforced Film of Example 2) A flame-retardant polyolefin-based reinforced film of Example 2, comprising a flame-retardant layer, a reinforcing layer, and a receiving layer, was obtained using the same materials and manufacturing method as in Example 1, except that a portion of the polyolefin-based resin in the resin composition used to form the flame-retardant layer was replaced with a biomass polyethylene resin (SBC818, manufactured by Braskem). The biomass polyethylene resin content was 10% of the total mass of the flame-retardant layer. The reinforced film of Example 2, like Example 1, has a configuration in which receiving layers are formed on both sides of a laminate consisting of a reinforcing layer sandwiched between two flame-retardant layers.

[0137] (Flame Retardancy Evaluation) The flame-retardant polyolefin-based reinforced film of Example 2 was subjected to a flame retardancy test using the 45° microburner method and 45° coil method specified in the flame retardancy performance test method of the Ministry of Internal Affairs and Communications Ordinance. For pretreatment, the reinforced film was immersed in 50°C warm water for 30 minutes. The test results using the 45° microburner method are shown in Table 8, and the test results using the 45° coil method are shown in Table 9. Note that the samples used in the 45° microburner method and the 45° coil method were different samples.

[0138]

[0139]

[0140] As shown in Tables 8 and 9, it was confirmed that the flame-retardant polyolefin-based reinforced film of Example 2 exhibited good flame retardancy. Therefore, it was confirmed that sufficient flame retardancy can be obtained even when the polyolefin-based resin contains biomass resin.

[0141] (Recyclability Evaluation) The flame-retardant polyolefin-based reinforced film of Example 2 was subjected to material recycling at a processing temperature of 210°C using a small re-pelletizing machine (manufactured by Nippon Yuki Co., Ltd.) to obtain a recycled resin. The MFR of the recycled resin was measured in accordance with ISO 1133 at a temperature of 230°C and a load of 2.16 kg. The resulting MFR of the recycled resin was 21.25 g / 10 min. This confirmed that a recycled resin with high processability could be obtained from the reinforced film of Example 2.

[0142] As explained in the above embodiments and examples, the flame-retardant polyolefin-based reinforced film 10 provides the following advantages: (1) The recycled resin of the flame-retardant polyolefin-based reinforced film 10 has an MFR of 10 g / 10 min or more and 50 g / 10 min or less, which improves the processability of the recycled resin for injection molding and extrusion molding.

[0143] (2) The mass proportions of the materials contained in the flame-retardant layer 11 are 40% to 80% polyolefin resin, 10% to 20% bromine-based compound, and 3% to 20% white pigment. This composition ensures the flame retardancy of the flame-retardant layer 11 and also provides good concealing properties due to the white pigment. Furthermore, the recycled resin of the reinforced film 10 is more likely to have good physical properties.

[0144] (3) The flame-retardant layer 11 is made of a resin composition having an MFR of 8 g / 10 min or more and 30 g / 10 min or less. This configuration makes the resin composition highly suitable for T-die extrusion molding. Forming the flame-retardant layer 11 by T-die extrusion molding allows for a thinner flame-retardant layer 11, thereby reducing the weight of the reinforced membrane 10.

[0145] (4) If the thickness of the flame-retardant layer 11 is 30 μm or more and 200 μm or less, it is possible to reduce the weight of the reinforced film 10. (5) The dry heat dimensional change rate at 150°C of the polyolefin fiber that makes up the reinforcing layer 12 is within the range of -5% to -50%. As a result, when a flame is ignited, the reinforcing layer 12 undergoes thermal contraction, moving the reinforced film 10 away from the fire source and allowing the remaining flame in the molten area to self-extinguish.

[0146] (6) The flame-retardant layer 11 is composed of a resin composition having a lower MFR than the resin constituting the polyolefin-based fibers of the reinforcing layer 12. The flame-retardant layer 11 is also composed of a resin composition having a lower flexural modulus than the resin constituting the polyolefin-based fibers of the reinforcing layer 12. This configuration ensures that the reinforcing function of the reinforcing layer 12 is adequately maintained, and the resin of the flame-retardant layer 11 complements the physical properties of the resin of the reinforcing layer 12. As a result, the characteristics of the recycled resin in the reinforced membrane 10 are not biased, and high-quality recycled resin is obtained.

[0147] (7) If the reinforcing layer 12 is sandwiched between two flame-retardant layers 11, the strength is increased compared to a two-layer structure. Furthermore, the rigidity of the reinforced curtain 10 is also increased, making it easier to handle during printing processes, etc. Furthermore, the reinforced curtain 10 is less likely to warp.

[0148] (8) If the flame-retardant layer 11 is sandwiched between two reinforcing layers 12, the strength is increased compared to a two-layer structure. Furthermore, the rigidity of the reinforced curtain 10 is also increased, making it easier to handle during printing processes, etc. Furthermore, the texture unique to the fabric is reflected in the appearance of the reinforced curtain 10, which improves the design of the reinforced curtain 10. Furthermore, wrinkles on the surface of the reinforced curtain 10 are less likely to be visible.

[0149] (9) The reinforced curtain 10 has a printable surface, which allows it to be used as a decorative material. (10) If the polyolefin-based fibers of the reinforcing layer 12 contain a pigment, the reinforcing layer 12 has enhanced concealing properties, which can reduce show-through when printing is applied to the surface of the reinforced curtain 10. Therefore, the reinforced curtain 10 can be used as a decorative material.

[0150] 10, 10A, 10B, 10C...Flame-retardant polyolefin-based reinforced film 11...Flame-retardant layer 12...Reinforcing layer 13...Receiving layer

Claims

1. A flame-retardant polyolefin-based reinforced curtain comprising a flame-retardant layer containing a polyolefin resin and a flame retardant, and a reinforcing layer composed of polyolefin fibers, wherein the recycled resin obtained by material recycling the reinforced curtain has a melt flow rate of 10 g / 10 min or more and 50 g / 10 min or less at 230°C and a load of 2.16 kg.

2. The flame-retardant polyolefin-based reinforced film according to claim 1, wherein the flame-retardant layer contains a bromine-based compound as the flame retardant and a white pigment, and the mass proportions of the materials contained in the flame-retardant layer are 40% or more and 80% or less of the polyolefin-based resin, 10% or more and 20% or less of the bromine-based compound, and 3% or more and 20% or less of the white pigment.

3. The flame-retardant polyolefin-based reinforced curtain according to claim 1, wherein the flame-retardant layer is composed of a resin composition having a melt flow rate of 8 g / 10 min or more and 30 g / 10 min or less at 230°C and a load of 2.16 kg.

4. The flame-retardant polyolefin-based reinforced curtain according to claim 1, wherein the thickness of the flame-retardant layer is 30 μm or more and 200 μm or less.

5. The flame-retardant polyolefin-based reinforced curtain according to claim 1, wherein the dry heat dimensional change rate of the polyolefin-based fiber at 150°C is within the range of -5% to -50%.

6. The flame-retardant polyolefin-based reinforced curtain according to claim 1, wherein the flame-retardant layer is composed of a resin composition having a melt flow rate lower than that of the resin constituting the polyolefin-based fiber.

7. The flame-retardant polyolefin-based reinforced curtain according to claim 1, wherein the flame-retardant layer is composed of a resin composition having a flexural modulus smaller than that of the resin constituting the polyolefin-based fiber.

8. The flame-retardant polyolefin-based reinforced curtain according to claim 1, comprising one reinforcing layer and two flame-retardant layers sandwiching the reinforcing layer.

9. The flame-retardant polyolefin-based reinforced curtain according to claim 1, comprising one flame-retardant layer and two reinforcing layers sandwiching the flame-retardant layer.

10. The flame-retardant polyolefin-based reinforced film according to claim 1, wherein the reinforced film has a printable surface.

11. The flame-retardant polyolefin-based reinforced curtain according to claim 10, wherein the polyolefin-based fiber contains a pigment.

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