JP2003260763A - Transparent flame-retardant film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent flame-retardant film having fire retardancy and transparency while it is used, which does not generate harmful gases such as a halogen-based gas or the like, and generates less ash during disposal and incineration after use. <P>SOLUTION: The transparent flame-retardant film composed of at least three layers comprising both outer layers and an interlayer. The interlayer is composed of a thermoplastic urethane resin and a condensation phosphoric ester, and the both outer layers are composed of olefin resin. The film has an oxygen index of 26 or greater, and a total luminous transmittance of 70% or higher. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has no self-extinguishing property (flame retardancy) without generating halogen-based gas during combustion, and can visually recognize an object under a film when coated. The present invention relates to a transparent flame-retardant film used for a curing sheet used for welding and painting, a case for stationery, a bag for packaging, and the like.

[0002]

2. Description of the Related Art As a transparent flame-retardant film, it is necessary to have a flame-retardant property at the time of use and to be able to see the inside when coated, so that it has been conventionally used in vinyl chloride resin. Those filled with a flame retardant were used. These have flame retardancy and excellent transparency.
However, these films are environmentally problematic because the vinyl chloride resin itself and the flame retardant generate halogen gas when incinerated. Therefore, olefin resins have been used instead of vinyl chloride resins. Also in the case of an olefin resin, a flame retardant and the like are added in the same manner as the vinyl chloride resin in order to obtain flame retardancy of the film itself. For example, phosphorus-based flame retardants, metal hydroxides or nitrogen-rich compounds are used alone or in combination. However, the flame-retardant film of the above-mentioned olefin resin has a problem that a large amount of ash is generated at the time of waste incineration, and especially when it is used as a curing sheet for a nuclear facility, this ash treatment becomes a serious problem. There are cases. In addition, such an olefin resin flame-retardant film is insufficient in terms of transparency and cannot be used in applications requiring visibility.

[0003]

DISCLOSURE OF THE INVENTION The present invention has flame retardancy and transparency when used, and when discarded and incinerated after use,
It is an object of the present invention to provide a flame-retardant transparent film that does not generate harmful gases such as halogen-based gas and that generates less ash.

[0004]

The flame-retardant transparent film of the present invention is a transparent flame-retardant film comprising at least three outer layers and an intermediate layer, in which the intermediate layer is a thermoplastic urethane resin and condensed phosphoric acid. It is formed of an ester, both outer layers are made of an olefin resin, and have an oxygen index of 26 or more and a total light transmittance of 70% or more. The oxygen index in the present invention is JIS K 7
It was obtained by a measuring method according to 210, and the oxygen index may be 26 or more. JIS total light transmittance
It was obtained by a measuring method according to K 7105,
When the total light transmittance is 70% or more, the coated material can be seen through the film when the material is coated in a painting operation or the like. The flame-retardant transparent film of the present invention is characterized in that the weight ratio of the thermoplastic urethane resin forming the intermediate layer to the condensed phosphoric acid ester is 95: 5 to 70:30. Furthermore, the flame-retardant transparent film of the present invention has a thickness ratio of the intermediate layer and both outer layers of 8: 1.
It is characterized by being ˜40: 1.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The flame-retardant transparent film of the present invention comprises
The thickness can be appropriately selected depending on the application used,
Usually, it is about 10 μm to 5 mm. Further, it has an oxygen index of 26 or more as flame retardancy and a total light transmittance of 70% or more as transparency. As a result, it has a self-extinguishing property when used and can be used as a transparent film.

As the thermoplastic urethane-based resin used as the intermediate layer, those made of polyester-based, polyether-based, polycarbonate-based urethane resins and the like can be used and can be appropriately selected depending on the use of the film. If desired, an olefin resin or an acrylic resin may be mixed and used.

The condensed phosphoric acid ester added to the thermoplastic urethane resin is water resistant and has a melting point of 90.degree.
It is preferably about 190 ° C. When the melting point is less than 90 ° C, blooming is likely to occur on the film surface due to aging and transparency is likely to decrease, which is not preferable. On the other hand, the melting point is 1
If it exceeds 90 ° C., the processing conditions will be higher than the usual processing conditions for the thermoplastic urethane film, and the thermoplastic urethane resin will be in an unmelted state, and the transparency of the intermediate layer will be reduced, which is not preferable. The phosphorus content of the condensed phosphoric acid ester is preferably 5 to 20%. When the phosphorus content is less than 5%, the flame retardancy is insufficient, and when it exceeds 20%, there is no problem in the flame retardancy, but there is a problem in ash or the like at the time of waste incineration.

The compounding ratio of the thermoplastic urethane resin and the condensed phosphoric acid ester is preferably about 95: 5 to 70:30. If the blending ratio of the condensed phosphoric acid ester is smaller than 95: 5, the desired flame retardancy cannot be obtained, which is not preferable. Further, if the blending ratio of the condensed phosphoric acid ester is larger than 70:30, there is no problem in terms of flame retardancy, but transparency is lowered, which is not preferable.

In the present invention, when the thermoplastic polyurethane resin is used in a single layer, there is no problem in transparency and flame retardancy, but it is sticky as a film, the slip property at the time of moldability is bad, and the release paper, etc. Must be used at the time of molding, and there is a problem of blocking when the film is wound. If an inorganic filler or the like is added to prevent this, the transparency will be reduced. Polyethylene resin, polyolefin resin, and a mixed resin thereof can be used as the olefin resin for both outer layers. Considering the transparency and flexibility of the film itself, it is selected from low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, and ethylene α-olefin polymer polymerized by a metallocene catalyst.
Olefin-based resins containing at least one ethylene-based polymer as a main component are preferable.

The thickness ratio between the intermediate layer and both outer layers of the flame-retardant transparent film of the present invention is preferably in the range of 8: 1 to 40: 1. If this ratio becomes larger than 8: 1 and the outer layer becomes thick, the influence of the combustion of the olefin resin in the outer layer becomes large, and the flame retardancy is lowered, which is not preferable. If this ratio is less than 40: 1, there is no effect of suppressing the elongation of the thermoplastic urethane-based resin layer of the intermediate layer at the time of molding, and it becomes sticky, resulting in a marked decrease in film moldability. Will end up.

As a method for laminating the intermediate layer and both outer layers, a usual laminating method or a coextrusion method is used. In the case of the laminating method, an adhesive layer may be provided on both sides of a thermoplastic urethane resin film formed in advance, and the olefin resin film formed in advance may be attached to each surface. The adhesive of the adhesive layer used here may be one that can bond the urethane resin and the olefin resin, but a maleic anhydride resin adhesive is preferred in the present invention. Moreover, you may integrate with extrusion by a T-die extruder by a co-extrusion method. In this case, the adhesive component may be added to the thermoplastic urethane-based resin or the olefin-based resin to perform co-extrusion with two kinds of three layers, or an adhesive layer may be provided.
It may be carried out by co-extrusion of 5 layers of seeds.

As the flame-retardant transparent film of the present invention, in order to secure more excellent transparency, an adhesive component is added to a thermoplastic urethane resin or an olefin resin without providing an adhesive layer. It is preferable to mold by two-kind three-layer coextrusion. As the adhesive component added in this case,
For example, a maleic anhydride resin can be added.
The addition amount is preferably 2 to 20% by weight. If the amount of the maleic anhydride-based resin added is less than 2% by weight, the adhesive strength between the intermediate layer and the outer layer will be insufficient, and if it exceeds 20% by weight, the transparency will decrease and the lubricity will be insufficient. It is not preferable because the surface is easily damaged.

[0013]

EXAMPLES The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. First, as a resin for the intermediate layer, an ether type thermoplastic urethane resin (Estran 5888 manufactured by NOVERON)
7) and condensed phosphoric acid ester (PX201 manufactured by Daihachi Chemical Co., Ltd.)
Phosphorus content of 9.0% and melting point of 168 ° C.) were mixed in the mixing ratio shown in Table 1 and kneaded with a twin-screw extruder to prepare pellets.
As the resin for the outer layer, ethylene / ethyl acrylate maleic anhydride resin (Bondyne TX8030 manufactured by Sumitomo Chemical) was dry blended with ultra-low density polyethylene (Excellen VL400 manufactured by Sumitomo Chemical) according to the formulation shown in Table 1. The two kinds of resins obtained above were mixed with a cylinder die temperature of 190 ° C. in a two-kind three-layer T-die extruder to form an intermediate layer,
A film having a thickness of 0.2 mm was obtained at the ratios of the outer layers shown in Table 1. Regarding the obtained film, (1)
The transparency, (2) flame retardancy, and (3) interlayer adhesion were evaluated by the following measuring methods, and the results are shown in Table 1. (1) Transparency The total light transmittance was measured according to JIS K 7105. (2) Flame retardance The oxygen index was measured according to JIS K 7210. (3) Interlayer Adhesion Cellophane tape was attached to the surface of the obtained film and peeled off in the direction of 90 degrees, and the appearance of the surface layer was evaluated. No abnormality on the surface layer: ○ The surface layer was peeled off: ×

[0014]

[Table 1]

From Table 1, in Experimental Example 1, since the condensed phosphoric acid ester was not added to the intermediate layer, the oxygen index was 22 and there was a problem in flame retardancy. In Experimental Example 6, since the amount of the condensed phosphoric acid ester added to the intermediate layer was large, the total light transmittance was 60%, which was insufficient in terms of transparency. In Experimental Example 7,
Although there is no problem in terms of transparency and flame retardancy, the adhesive strength between the intermediate layer and the outer layer was insufficient because no ethylene / ethyl acrylate maleic anhydride resin was added to the outer layer.
In Experimental Example 11, there is no problem in terms of transparency and flame retardancy, but the surface strength of the outer layer is insufficient in terms of scratch resistance due to the large amount of ethylene / ethyl acrylate maleic anhydride resin added to the outer layer. It was In Experimental Example 14, there were no problems in terms of flame retardancy and transparency, but stickiness was generated on the surface due to the lack of the thickness of the outer layer, and there was a problem in molding workability and the like. There were no particular problems in Experimental Examples 2 to 6, 8 to 10, and 12, 13.

[0016]

EFFECTS OF THE INVENTION The flame-retardant transparent film of the present invention is excellent in transparency because it uses a thermoplastic urethane resin for the intermediate layer. Since the olefin resin is provided in the outer layer, it has excellent physical properties as a film, no halogen-based gas is generated during disposal and incineration, and no inorganic filler is added. It has a low ash content after incineration.

Claims (3)

[Claims] 1. A transparent flame-retardant film comprising at least three outer layers and an intermediate layer, wherein the intermediate layer is formed of a thermoplastic urethane resin and a condensed phosphate ester, and both outer layers are formed of an olefin resin. A transparent flame-retardant film having an oxygen index of 26 or more and a total light transmittance of 70% or more. 2. The weight ratio of the thermoplastic urethane resin forming the intermediate layer to the condensed phosphoric acid ester is 95: 5 to 70: 3.
It is 0, The transparent flame-retardant film of Claim 1 characterized by the above-mentioned. 3. The thickness ratio between the intermediate layer and both outer layers is 8: 1 to 4.
It is 0: 1, The transparent flame-retardant film of Claim 1 or 2 characterized by the above-mentioned.