JP7775586B2 - Flame-retardant polyolefin decorative material and advertising medium using the same - Google Patents

Description

The present invention relates to flame-retardant polyolefin-based decorative materials and advertising media using the same.

Traditionally, fiber-reinforced products have been obtained by using synthetic woven or knitted fiber fabrics as a core material and forming a conventional polyvinyl chloride resin layer on the surface, or reinforced sheets such as tarpaulins and canvas formed by coating or laminating a vinyl chloride resin composition layer onto a woven fiber fabric. These products have been used in applications for buildings and structures, such as tents, sheet warehouses, construction site protection sheets, and soundproofing sheets for construction sites. In these cases, they have a relatively long lifespan and can be reused at the next construction site.

On the other hand, similar materials are also used in large advertising media such as "large board advertisements," "banners," "hanging banners," and "building wall display advertisements" that target consumers and are used on the rooftops and walls of buildings in business districts, downtown areas, and in front of train stations. However, tarpaulins and other advertising media cannot be reused in their original state because the advertising period is short and advertisements are printed all over the surface.

Furthermore, because tarpaulin is a composite material with a core of synthetic knitted or woven polyester fiber and a surface layer of polyvinyl chloride resin, separating these materials makes it difficult to recycle. Because polyvinyl chloride resin contains chlorine in its molecular structure, it generates hydrogen chloride gas, a corrosive gas, when burned, and, depending on the combustion conditions, may also generate toxic gases such as dioxins. As a result, when it comes to disposal, tarpaulin material, which is primarily made of polyvinyl chloride and contains a large amount of chlorine, can damage furnaces when incinerated and can generate harmful substances such as hydrogen chloride, so landfilling, which is considered to be a high environmental burden, is the mainstream method.

In addition, in order to realize a sustainable society, as exemplified by the SDGs, attention is being focused on materials that do not rely on landfill disposal as much as possible. In recent years, environmental issues such as the problem of microplastics have intensified, and Japan produces approximately 10 million tons of plastic waste per year, of which approximately 740,000 tons are landfilled and approximately 1.5 million tons are exported overseas. However, in July 2017, the Chinese government announced the "Implementation Plan for Reform of the Solid Waste Import Management System," and China's import ban began in 2018. As a result of China's measures, exports to Malaysia, Vietnam, Thailand, and other countries have increased, but ASEAN countries are also moving to ban imports.

In addition, conventional architectural canvas and tarpaulin materials are primarily made of polyvinyl chloride resin, which itself has high flame retardancy. Therefore, adding a small amount of flame retardant such as antimony trioxide (5 to 20 parts by weight) can make them flame-retardant, enabling them to comply with the fire-resistant standards stipulated in the Fire Service Act (Fire Service Act Enforcement Regulations Article 4: JIS Standard L-1091).

On the other hand, polyolefin resins such as polyethylene (PE) and polypropylene (PP), which do not contain halogens such as chlorine, are the most widely produced and are a type of general-purpose resin used in a variety of fields in everyday life. They are easy to recycle and have a well-established market as part of social infrastructure. However, when the constituent resins of these canvases and tarpaulins are replaced with polyolefin-based resins, the polyolefin-based resins themselves are highly flammable, making it essential to incorporate a flame retardant to impart flame resistance to these resins. Technology has been proposed that uses a flame retardant in combination with an antioxidant (see Patent Document 1), but depending on the type of antioxidant used, it has sometimes been difficult to achieve sufficient flame retardancy.

Patent No. 5503071

The present invention was conceived to reduce the amount of halogen-based flame retardants added while still requiring their use. Its objective is to provide flame-retardant polyolefin decorative materials and advertising media using the same that have excellent flame retardancy, weather resistance, mechanical strength, and flexibility, and that can be recycled without relying on incineration or landfill disposal when disposed of.

In order to solve the above problems, the present invention
The flame-retardant polyolefin decorative material is characterized by being a laminate consisting of at least three layers, including a flame-retardant polyolefin resin film formed from a flame-retardant polyolefin resin containing at least a polyolefin resin, a shielding additive which is a white pigment, and a flame retardant, and a fiber structure base fabric composed of fibers formed by stretching polyolefin resin at a stretch ratio within a range of 2 to 15 times bonded to the front and back of the flame-retardant polyolefin resin film.
This flame-retardant polyolefin decorative material is formulated with 50 to 200 parts by weight of a metal hydrate as a flame retardant and 20 to 80 parts by weight of a bromine-based flame retardant per 100 parts by weight of polyolefin resin, with the total amount of polyolefin resin being 50 wt% or less.

The present invention also provides a flame-retardant polyolefin decorative material, which is a laminate consisting of at least three layers, comprising a fiber structure base fabric made of fibers stretched from polyolefin resin at a stretch ratio within the range of 2 to 15 times, and flame-retardant polyolefin resin films bonded to the front and back of the fiber structure base fabric, the flame-retardant polyolefin resin films being formed from flame-retardant polyolefin resin containing at least polyolefin resin, a shielding additive which is a white pigment, and a flame retardant, the front and back surfaces of which are made of the flame-retardant polyolefin resin films.
This flame-retardant polyolefin decorative material is formulated with 50 to 200 parts by weight of a metal hydrate as a flame retardant and 20 to 80 parts by weight of a bromine-based flame retardant per 100 parts by weight of polyolefin resin, with the total amount of polyolefin resin being 50 wt% or less.

The flame-retardant polyolefin resin film may be one in which 0.5 to 10 parts by weight of the shielding additive is blended with 100 parts by weight of the polyolefin resin.

Furthermore, the flame-retardant polyolefin resin film may further contain 10 to 50 parts by weight of antimony trioxide as the flame retardant per 100 parts by weight of the polyolefin resin.

The flame-retardant polyolefin resin film may have a melt flow rate (MFR) of 0.5 to 50.0 g/10 min.

Furthermore, the shape of the fiber structure base fabric may be selected from filament yarn, multifilament yarn, monofilament yarn, tape yarn, split yarn, and split yarn.

A print image-receiving layer may also be provided on the surface of the flame-retardant polyolefin decorative material.

The present invention also provides an advertising medium characterized by being formed by printing on the flame-retardant polyolefin decorative material according to any one of claims 1 to 7 .

The advertising medium according to claim 8 , further characterized in that a resin eyelet is provided on the outer periphery.

According to the present invention, when the flame-retardant polyolefin resin film and the fiber structure base fabric melt during a flame ignition test, the residual stress in the stretched fiber structure base fabric is released, causing it to shrink thermally and move away from the fire source. At the same time, the physical action caused by the thermal shrinkage makes the remaining flame in the molten area more likely to fall off, thereby promoting the self-extinguishing function.

As a result, the material has excellent flame retardancy, weather resistance, mechanical strength, and flexibility. Furthermore, it is possible to provide flame-retardant polyolefin decorative materials and advertising media using them that are recyclable and do not rely on incineration or landfill disposal when disposed of.

1 is a cross-sectional view showing the layer structure of a flame-retardant polyolefin decorative material according to the present invention. FIG. 3 is a cross-sectional view showing another layer structure of the flame-retardant polyolefin decorative material according to the present invention.

Embodiments of the present invention will be described below with reference to the drawings. Each of the embodiments shown below exemplifies a configuration that embodies the technical concept of the present invention, and the technical concept of the present invention is not limited to the materials, shapes, structures, etc. of the components described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

Figure 1 is a cross-sectional view showing the layer structure of the flame-retardant polyolefin decorative material of the present invention. As shown in Figure 1, the flame-retardant polyolefin decorative material of the present invention is a laminate comprising a flame-retardant polyolefin resin film 10 and a fiber structure base fabric 20 bonded to both sides of the film.

The flame-retardant polyolefin resin film is a film made from a flame-retardant polyolefin resin containing a polyolefin resin, a white pigment, a shielding additive, and a flame retardant, and the fiber structure base fabric 2 is made from fibers stretched from a polyolefin resin at a stretch ratio within the range of 3 to 15 times.

<Flame-retardant polyolefin resin film>
Examples of polyolefin resins that can be used in flame-retardant polyolefin resin films include ethylene-α-olefin copolymers, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, ethylene-methacrylic acid copolymers, ethylene-methacrylic acid ester copolymers, ethylene-methyl methacrylic acid copolymers, ethylene-methyl methacrylic acid ester copolymers, ethylene-ethyl acrylic acid copolymers, ethylene-ethyl acrylic acid ester copolymers, and mixtures of two or more of these. The polyolefin resins used in the present invention can be those produced by radical polymerization or ionic polymerization.

Polyethylene resins obtained by radical polymerization include polymers of ethylene alone and copolymers obtained by copolymerizing ethylene with a monomer that can be radically polymerized with ethylene.

The flame retardants used in flame-retardant polyolefin resin films preferably include metal hydrates, bromine-based compounds, and inorganic compounds. Metal hydrates include aluminum hydroxide and magnesium hydroxide, which rapidly lower the combustion temperature by absorbing heat from dehydration during combustion, and are effective in suppressing the generation of flammable gases due to the thermal decomposition of plastics.

Bromine-based flame retardants include non-drip flame retardants that act directly on the combustion mechanism, such as by trapping OH radicals in the gas phase, blocking oxygen by generating flame-retardant inert gases, and diluting oxygen, as well as drip flame retardants that physically remove the burning part by reducing the viscosity of the plastic during combustion and causing the embers to fall. The preferred amounts of these additives are 50 to 200 parts by weight of metal hydrate and 20 to 80 parts by weight of bromine-based flame retardant per 100 parts by weight of polyolefin resin.

Inorganic flame retardants include antimony oxide compounds such as antimony trioxide and antimony pentoxide. It is preferable to add antimony trioxide as a flame retardant, preferably in an amount of 10 to 50 parts by weight per 100 parts by weight of polyolefin resin. When used in combination with a bromine-based flame retardant, a heavy flame-retardant gas containing antimony is generated, synergistically enhancing the oxygen blocking and oxygen dilution effects. Inorganic flame retardants such as zinc borate and zinc stannate also suppress smoke generation and reduce afterglow by promoting the formation of graphite-like char during combustion, and the formation of a gas barrier layer enhances the flame retardant effect.

Furthermore, adding excessive amounts of the above flame retardants to impart sufficient flame retardancy can reduce the processability of the polyolefin resin composition and significantly reduce the mechanical strength of the processed product. In such cases, adding a small amount of a modified polyolefin resin grafted with maleic anhydride is a good solution. The addition of maleic anhydride reduces the polarity of the polyolefin resin and significantly improves adhesion. Therefore, when inorganic fillers such as metal hydrate flame retardants are highly loaded, the interfacial adhesion between the filler and the resin improves, improving dispersibility and reducing voids in the resin, resulting in improved rigidity and strength of the processed product. Furthermore, improving the dispersibility of metal hydrate flame retardants improves the efficiency of the endothermic reaction during combustion, thereby enhancing the flame retardant effect.

Furthermore, because the flame-retardant polyolefin decorative material of the present invention is intended for outdoor use, color changes such as yellowing, along with resin degradation due to ultraviolet rays, are also important factors to control. Therefore, it is preferable to add a white pigment/shielding additive, preferably in an amount of 0.5 to 10 parts by weight per 100 parts by weight of polyolefin resin. Examples of white pigment/shielding additives include titanium oxide, zinc borate, and zinc oxide. Furthermore, there are two types of titanium oxide for industrial use: rutile and anatase. For the additive of the present invention, the rutile type, which has a high refractive index, is preferable.

The primary factor in the optical properties of inorganic pigments is the refractive index; the higher the refractive index, the greater the surface reflection, which improves light scattering in the resin and tends to increase hiding power. This can reduce yellowing of the resin due to ultraviolet rays. Rutile type (Rutile): Refractive index 2.72. Anatase type (Anatase): Refractive index 2.52.

Titanium dioxide also has the advantage of being able to strongly absorb light with wavelengths shorter than 400 nm, but not visible light. This allows it to have similar effects to light stabilizers and UV absorbers, allowing for the addition of fewer of these additives. Titanium dioxide also has photocatalytic properties, exerting a powerful oxidizing power on its surface when exposed to light. This property is used industrially to break down difficult-to-decompose substances. However, if its oxidizing power is exerted within or on the surface of the resin, it can lead to quality degradation, such as resin degradation or peeling of the printed surface. Therefore, it is recommended to use it after surface treatment to suppress its oxidizing power. Examples of surface treatment agents and dispersants include silica, aluminum hydroxide, dimethicone, cyclopentasiloxane, triethoxycaprylylsilane, hydrogen dimethicone, isostearic acid, stearic acid, alumina, and sodium polyacrylate.

In addition, it is desirable to add a light-blocking agent such as an ultraviolet absorber. UV absorbers include benzotriazoles and benzophenones, which absorb ultraviolet light in the 320-350 nm range, the region to which plastics are most susceptible. Furthermore, using them in combination with HALS can impart even greater light stability. Typical examples include BASF's Tinuvin series and Uvinul series, and ADEKA's LA series.

In addition, when compounding the flame-retardant polyolefin resin described above, additives can be added to improve processing stability, weather resistance, strength, etc.

Additional agents to improve processability include lubricants, antioxidants, light stabilizers, UV absorbers, and antistatic agents. In particular, a significant amount of metal hydrate flame retardant is added to improve flame retardancy, which makes shear heat generation more likely during the compounding and film-forming processing stages. Therefore, the addition of a lubricant is necessary. Adding a lubricant reduces friction between the synthetic resin and the processing machine, as well as between the synthetic resin particles themselves. Lubricants that are used include hydrocarbons, fatty acids, fatty alcohols, fatty amides, and metal soaps. It is usually desirable to use multiple lubricants in combination, taking into account the balance between external and internal lubrication.

In addition, it is advisable to add an antioxidant to prevent resin deterioration due to shear heat or when using outdoors. Antioxidants are divided into primary antioxidants, which act as radical scavengers, and secondary antioxidants, which act as peroxide decomposers. Phenolic antioxidants are commonly used to scavenge radicals, stabilizing ROO· (alkoxy radicals) generated from radicals generated by ultraviolet light or thermal energy and oxygen. There are three types of chemical structures: hindered, semi-hindered, and less hindered, which differ in the number of radicals they scavenge and the reaction rate. Generally, olefin-based resins are relatively stable, and oxidation reactions proceed slowly, so a slow-acting hindered type is effective. Typical antioxidants include the Irganox series manufactured by BASF and the AO series manufactured by ADEKA.

Furthermore, plastic peroxides (ROOH radicals) are generated as a reaction product of radical scavenging by phenolic antioxidants, and if left unattended, they will further decompose into radicals and deteriorate. To prevent this, sulfur- or phosphorus-based antioxidants, which have the peroxide decomposition ability to break down ROOH into stable substances, are used. However, sulfur-based antioxidants emit an odor at high temperatures and are difficult to color, making them unsuitable for creating white sheets; therefore, it is preferable to use phosphorus-based antioxidants. Representative phosphorus-based antioxidants include Irgafos 168 manufactured by BASF and the PEP series and 2112 manufactured by ADEKA.

In addition, to improve weather resistance, it is desirable to add a light stabilizer (HALS), which captures radicals generated by ultraviolet light, preventing discoloration and maintaining gloss. However, when used in combination with brominated flame retardants, trace amounts of acidic substances are generated in the resin, and because regular HALS are alkaline, a neutralization reaction occurs in the resin, resulting in an antagonistic effect. For this reason, it is desirable to use NOR-type HALS, which are less likely to form salts with acidic substances. Typical examples include the Tinuvin series made by BASF and the LA series made by ADEKA.

Furthermore, in the flame-retardant polyolefin resin film 10, it is preferable that the total amount of the polyolefin resin is 50 wt% (weight %) or less, and that the melt flow rate (MFR) of the flame-retardant polyolefin resin described above is 0.5 to 50.0 g/10 min. If the melt flow rate is less than 0.5 g/10 min, molding processing may become extremely difficult, and if it is higher than 50.0 g/10 min, the mechanical strength will be insufficient.

Flame-retardant polyolefin resin films can be molded using methods such as T-die extrusion film production, calendar film production, and inflation film production. When producing thin films of around 50 to 150 μm, T-die film production is suitable, as it offers a wide range of adjustments for extrusion volume, lip width, take-up speed, etc. On the other hand, when producing films or sheets with thicknesses exceeding 150 μm, calendar film production is suitable, as it is easier to increase the extrusion volume and is highly productive.

<Fiber structure base fabric>
The fiber structure base fabric 20 is preferably a nonwoven fabric or woven fabric made of polyolefin resin flat yarn, the shape of which is selected from filament yarn, multifilament yarn, monofilament yarn, tape yarn, split yarn, and split yarn.

To form polyolefin multifilament yarn, polyolefin resin is melt-kneaded in an extruder and extruded into a long, thin rod. It is then stretched at 2-3 times the normal speed while being heated, homogenizing the molecular orientation of the polyolefin resin and increasing its strength, before being turned into fiber.

When considering strength, flexibility, and texture when finished, it is generally desirable for the yarn used in the reinforcing material of this invention to be in the range of 80 to 200 denier. Furthermore, polyolefin resin has a lower melting point than polyester resin, which is a typical example of ordinary chemical fibers, and is therefore more susceptible to breakage due to frictional heat during fiber processing and subsequent weaving and knitting processes. Therefore, it is desirable to set the filament count of the filament yarn to a low level. Furthermore, when using thin yarn, care must be taken to avoid problems such as the fibers becoming more susceptible to breakage in the subsequent fabric manufacturing process.

The polyolefin flat yarn is formed by melt-kneading the polyolefin resin in an extruder, forming a film using the inflation method or T-die method, slitting the film to a width of approximately 10 to 20 mm, stretching the film, and then heat-treating it to form a flat yarn. The stretching process is carried out at a temperature below the melting point and above the softening point of the polyolefin. Any heating method, including hot rolls, hot plates, infrared rays, and hot air, can be used. The slit polyolefin film is heated and stretched by varying the peripheral speed difference between the front and rear rolls. The stretching ratio is preferably 3 to 15 times, more preferably 5 to 10 times. A stretching ratio of less than 3 times may result in insufficient mechanical strength. On the other hand, a stretching ratio of more than 15 times may make it difficult to stretch using conventional methods, requiring expensive equipment, and other problems. Stretching in multiple stages is preferred to prevent uneven stretching.

The polyolefin flat yarn obtained in this manner is used as the warp and weft yarns to form a woven or knitted fabric. The weave of the woven or knitted fabric is not particularly limited; examples of woven fabrics include plain weave, twill weave, twill weave, ramie weave, and leno weave, while examples of knitted fabrics include raschel knit, tricot knit, and Milanese knit. The weft and warp yarn density is typically in the range of 5 to 40 threads/2.54 cm, and preferably 10 to 30 threads/2.54 cm.

An example of a commercially available woven fabric is Tarpee Cloth (trade name) manufactured by Hagiwara Kogyo Co., Ltd. In addition to woven and knitted fabrics, two sheets of the resulting polyolefin flat yarn are stacked together so that the main fibers are approximately perpendicular to each other, and then heated and welded together. A mesh-like nonwoven fabric may also be used. Representative commercially available examples of such mesh-like nonwoven fabrics include Warif (registered trademark) and CLAF (registered trademark) manufactured by JX ANCI, and Sof (trade name) manufactured by Sekisui Film Co., Ltd.
When such a fiber structure base fabric catches fire, the higher the draw ratio, the more volumetric shrinkage occurs, moving it away from the flame, resulting in improved flame retardancy.

The flame-retardant polyolefin resin film 10 and the fiber structure base fabric 20 are laminated by laminating the film on both sides of the base fabric. The lamination method may involve providing an adhesive layer between the film and the base fabric, or lamination and fusion bonding without adhesive. In this embodiment of the present invention, the flame-retardant polyolefin resin film molded by the calendaring method and the fiber structure base fabric are laminated via adhesive 3.

When laminating, the flame-retardant polyolefin resin film 10 may be subjected to corona discharge treatment, chromic acid oxidation treatment (wet), flame treatment, hot air treatment, ozone plasma irradiation treatment, or adhesion enhancement treatment on the surface facing the print image-receiving layer 30. By applying these treatments, the surface of the flame-retardant polyolefin resin film 10 facing the print image-receiving layer 30 improves the wettability of the coating agent containing a metal material used in forming the print image-receiving layer 30, thereby improving the adhesion of the print image-receiving layer 30 to the flame-retardant polyolefin resin film 10. These surface treatment methods are selected appropriately depending on the type of flame-retardant polyolefin resin film 10, but corona discharge treatment and ozone plasma irradiation treatment are preferred in terms of adhesion to the print image-receiving layer 30 and the operability of the processing equipment.

In addition, the adhesion of the print image-receiving layer 30 to the flame-retardant polyolefin resin film 10 may be improved by forming an anchor layer or primer layer on the surface of the flame-retardant polyolefin resin film 10 facing the print image-receiving layer 30. There are various types of anchor agents and primer agents. For water-based materials such as alcohol-based materials with high surface tension, it is desirable to increase the surface tension to around 70 dynes. For solvent-based materials or materials with low surface tension such as urethane, appropriate coating may be possible even with a surface tension of around 50 dynes.

<Printing image-receiving layer>
The print image-receiving layer 30 is a layer provided to improve printability and weather resistance of the print, and is provided by dissolving an acrylic or urethane resin or the like in a solvent, applying it to a fiber structure base fabric and drying it, or by forming the resin into a film and adhering it.
In addition, when the flame-retardant polyolefin decorative material and the advertising medium using it are used for an extremely short period of time, printing can be done directly with a UV inkjet printer without applying the print image-receiving layer 30 .

<Manufacturing advertising media>
1) Printing Step When the flame-retardant polyolefin resin sheet obtained by the above method is used as an advertising medium, it is necessary to print a pattern on it.
The most common method for printing images is by inkjet printer. There are several printing methods for inkjet printers, but they are not particularly limited. Typical inkjet printer methods include:

a) Latex inkjet printer: This is a printer that uses so-called "water-based pigment" ink, in which the pigment is dissolved in water. Latex ink contains four main components: water, latex (polymer), pigment (color component), and scratch-resistant material. It is characterized by being a volatile organic compound (VOC) and having less odor than solvents, and is often used for display purposes in hospitals, educational facilities, and stores.

b) Solvent inkjet printer: Solvent-based ink contains pigment in a dilute organic solvent. When the ink lands on the surface to be printed, the solvent components first attack the surface of the media. In other words, it dissolves the surface of the media, allowing the ink to penetrate slightly into the media. After that, the solvent evaporates, allowing the pigment to adhere to the media and providing high weather resistance. Because it uses a solvent, a solvent smell remains after printing, making it unsuitable for indoor displays.

c) UV inkjet printer: When UV ink is exposed to the equipment's UV light (ultraviolet), the monomer components contained in the ink polymerize and solidify, allowing the ink to set. While solvent ink erodes the surface of the media, UV printing forms an image when the ink is solidified on the object to be printed. Because the ink solidifies the moment it is exposed to UV light, the product can be immediately sent for post-processing such as cutting and sewing after printing.

2) Sewing and Grommet Processing Process When manufacturing advertising media such as banners and hanging banners, it is necessary to fold back and sew the edges and then process the grommets around the periphery to attach strings when displaying. Typically, sewing thread made from polyester resin is used, and the grommets are often made from metal materials such as aluminum or brass. However, these sewing threads and grommets must be removed during the recycling process after use, which is inefficient.

Therefore, it is desirable to use polyolefin resin for each component so that the sewing and eyelet processing processes can be carried out together in the recycling process.
Representative examples of sewing threads include Toyobo's Izanas (registered trademark), Asahi Kuma's Pylen thread, Mitsubishi Chemical's Pylen (registered trademark), etc. Regardless of the above, any thread made of olefin resin is acceptable.

The eyelets are manufactured by injecting olefin resin into a mold. While conventional metal and polycarbonate eyelets are fastened by crimping like rivets, olefin resin eyelets cannot be fastened by crimping due to the properties of the resin. Therefore, male-female mating resin eyelets were inserted into multiple holes on the periphery of the flame-retardant polyolefin decorative material.

Figure 2 shows the layer structure of another flame-retardant polyolefin-based decorative material. It comprises a fiber structure base fabric 50, flame-retardant polyolefin-based resin films 60 on both sides of the fiber structure base fabric 50, and a print image-receiving layer 70 on at least one side of the flame-retardant polyolefin-based resin film 60. The method for bonding the fiber structure base fabric 50 and the flame-retardant polyolefin-based resin film 60 is as described above. Even with this layer structure, it is possible to produce a flame-retardant polyolefin-based decorative material that can be printed on both sides.

In the case of such a layer structure, the thickness of the flame-retardant polyolefin resin film 60 must be thin to ensure the flexibility of the resulting structure, and it is desirable for it to be constructed with a thickness of 100 microns or less.

Forming methods used in this process include extrusion molding using a T-die, lamination processing, and film formation using inflation molding. Furthermore, the lamination method is not particularly limited, although it is desirable from a manufacturing cost perspective to use thermal lamination, which utilizes the heat generated during molding and is carried out simultaneously with the molding process. Other methods include lamination using a heated roll in the next step, and spraying hot melt adhesive to adhere the film.

The subsequent formation of the print image-receiving layer 70 and manufacturing of the advertising medium are as described above.

The present invention will now be explained in more detail using examples.

Example 1
A 230 μm thick flame-retardant polyolefin resin film was molded using a compound with a melt flow rate (MFR) of 0.5 to 50.0 g/10 min, containing 100 to 200 parts by weight of a metal hydrate as a flame retardant, 20 to 80 parts by weight of a bromine-based flame retardant, and 10 to 50 parts by weight of titanium oxide and antimony trioxide as white pigment/shielding additives, per 100 parts by weight of polyolefin resin. The resulting film was coated with 2 to 30 g/ ^m² of olefin hot melt adhesive using a hot melt spray method, and then a plain woven base fabric of 100 denier multifilament yarn was bonded to both sides as a fiber structure base fabric to create a flame-retardant polyolefin decorative material. Furthermore, since the flame-retardant polyolefin decorative material of this example has a structure in which a flame-retardant polyolefin resin film is sandwiched between a fiber structure base fabric, wrinkles that occur in the flame-retardant polyolefin resin film are difficult to see from the outside.

Example 2
An olefin-based hot melt was applied to a mesh nonwoven fabric (CLAF, manufactured by JX Nippon Oil & Energy) as a fiber structure base fabric using a hot melt spray method at a weight of 2 to 30 g/ ^m² , and then a 230 μm thick flame-retardant polyolefin-based resin film was laminated using a compound with a melt flow rate (MFR) of 0.5 to 50.0 g/10 min, which was made by blending 100 to 200 parts by weight of a metal hydrate as a flame retardant, 20 to 80 parts by weight of a bromine-based flame retardant, and 10 to 50 parts by weight of titanium oxide and antimony trioxide as white pigment/shielding additives, per 100 parts by weight of polyolefin-based resin.The compound was then rolled using an inverted L-type four-roll calender at a temperature of 150 to 200°C to produce a flame-retardant polyolefin-based decorative material.

Strength tests and flame retardancy tests were conducted on the flame-retardant polyolefin decorative materials of Examples 1 and 2.

<Strength test>
Test 1) Tensile strength JIS P8113 3.1 Paper and paperboard - Test methods for tensile properties Part 2: Constant rate extension method Tensile strength test piece width: 15 mm (test results converted to 1 m width)
Grip spacing: 100 mm
Test speed: 20 mm/min. Equipment used: Shimadzu Autograph AG-X 10 kN (load cell 1 kN)
Test 2) Tear strength JIS P8116 3.1 Paper - Tear strength test method Elmendorf tear tester method Number of sheets stacked: 4 sheets (test results converted to values per sheet)
Equipment used: Elmendorf tear tester manufactured by Yasuda Seiki Seisakusho Test 3) Burst test JIS L 1096 Burst strength: The fabric is burst using a burst tester to examine the strength of the fabric.
Equipment used: Burst testing machine manufactured by Yasuda Seiki Seisakusho.

The test results are shown in Table 1.

The Reference Example shown in Table 1 is the sheet itself molded from the compound described above, while Examples 1 and 2 are three sheets obtained by laminating a reticular nonwoven fabric (manufactured by JX Nippon Oil & Energy Corporation) called CLAF as a fiber structure base fabric layer.

The results in Table 1 confirm that the strength is significantly improved by attaching a fiber structure base fabric layer.

<Flame retardancy test>
Details of the flame retardancy test are as follows: Indoor and outdoor banners, hanging banners, and other decorative items are subject to flame retardancy regulations under the Fire Service Act, and must comply with the test methods set out in Article 4-3, Paragraphs 3 to 7 of the Enforcement Regulations of the Fire Service Act. The test standard applied is JIS L 1091, Flammability Test Method for Textile Products, and the test method differs depending on the basis weight of the test object.

The flame-retardant polyolefin decorative material produced this time exceeded 450 g/ ^m² , so it was tested using the A-2 method (45° microburner method) and judged according to the evaluation criteria for Category 3. Table 2 shows the test criteria for Category 3 of the JIS L 1091A | = -1 method, and Table 3 shows the test results.

The results in Tables 3 and 4 show that all flame-retardant polyolefin decorative materials achieved good results, meeting the standards of JIS L 1091A-1, Category 3.

<Recycling test>
Next, a recycling test was conducted to see if plastic flower pots could be produced using samples of advertising media printed with the above flame-retardant polyolefin decorative material using a UV inkjet printer. The outline of the recycling test is as follows:

- Purpose of the test: To re-pelletize the advertising media samples and measure their basic physical properties. Also, to confirm whether they could be molded into flower pots and used.
Test procedure: Crushing → Re-pelletization → Injection molding → Flowerpot creation Mixing ratio: 100% re-pelletized

As a result, it was confirmed that flowerpots with sufficient strength could be manufactured using printed advertising media samples, even when re-pelletized. It was also confirmed that the flame-retardant polyolefin resin film of the flame-retardant polyolefin decorative material of the present invention can be used.

As a result, the flame-retardant polyolefin decorative material of the present invention has excellent flame retardancy, weather resistance, mechanical strength, and flexibility. Furthermore, when discarded after use as an advertising medium, it can be recycled without relying on incineration or landfill disposal.

10: Flame-retardant polyolefin-based resin film 20: Fiber structure base fabric 30: Printed image-receiving layer 50: Fiber structure base fabric 60: Flame-retardant polyolefin-based resin film 70: Printed image-receiving layer

Claims (9)

The laminate is composed of at least three layers, and includes a flame-retardant polyolefin resin film formed from a flame-retardant polyolefin resin containing at least a polyolefin resin, a shielding additive which is a white pigment, and a flame retardant, and a fiber structure base fabric made of fibers obtained by stretching a polyolefin resin at a stretch ratio within a range of 2 to 15 times bonded to the front and back of the flame-retardant polyolefin resin film,
50 to 200 parts by weight of a metal hydrate and 20 to 80 parts by weight of a bromine-based flame retardant are blended with 100 parts by weight of the polyolefin-based resin,
The total amount of the polyolefin resin is 50 wt % or less
A flame-retardant polyolefin decorative material characterized by: A laminate consisting of at least three layers, comprising a fiber structure base fabric made of fibers obtained by stretching a polyolefin resin at a stretch ratio within a range of 2 to 15 times, and flame-retardant polyolefin resin films formed by forming films of a flame-retardant polyolefin resin containing at least a polyolefin resin, a shielding additive which is a white pigment, and a flame retardant on the front and back sides of the fiber structure base fabric, the front and back sides being made of the flame-retardant polyolefin resin films,
50 to 200 parts by weight of a metal hydrate and 20 to 80 parts by weight of a bromine-based flame retardant are blended with 100 parts by weight of the polyolefin-based resin,
The total amount of the polyolefin resin is 50 wt % or less
A flame-retardant polyolefin decorative material characterized by: The flame-retardant polyolefin-based decorative material according to claim 1 or 2, characterized in that the flame-retardant polyolefin-based resin film contains 0.5 to 10 parts by weight of the shielding additive per 100 parts by weight of the polyolefin-based resin. The flame-retardant polyolefin-based decorative material according to any one of claims 1 to 3, characterized in that the flame-retardant polyolefin-based resin film further contains 10 to 50 parts by weight of antimony trioxide as the flame retardant per 100 parts by weight of the polyolefin-based resin. The flame-retardant polyolefin decorative material according to any one of claims 1 to 4, characterized in that the flame-retardant polyolefin resin film has a melt flow rate (MFR) of 0.5 to 50.0 g/10 min. 6. The flame-retardant polyolefin decorative material according to claim 1, wherein the fiber structure base fabric has a shape selected from the group consisting of filament yarn, multifilament yarn, monofilament yarn, tape yarn, split yarn, and split yarn. 7. The flame-retardant polyolefin decorative material according to claim 1, wherein a print image-receiving layer is provided on the surface of the flame-retardant polyolefin decorative material. 8. An advertising medium comprising the flame-retardant polyolefin decorative material according to claim 1, printed thereon. 9. The advertising medium according to claim 8 , wherein a resin eyelet is provided on the outer periphery.