JP4398307B2 - Curing film for nuclear facilities - Google Patents

Description

  The present invention relates to a curing film or sheet (hereinafter referred to as “film” in this specification) in facilities such as nuclear power plants and nuclear research laboratories that handle radioactive substances (hereinafter, these facilities are collectively referred to as nuclear facilities). "Is related to a curing film for nuclear facilities used as a" sheet "). Specifically, the present invention relates to a curing film for nuclear facilities which is produced by inflation molding, has excellent flame retardancy and workability (or flexibility), and is excellent in other various characteristics.

  Curing films used for construction and periodic inspections at nuclear facilities such as nuclear power plants are used to prevent fire and to cover floors, walls, ceilings, shelves or equipment. Workability (or flexibility) is required.

On the other hand, the cured film after use may be incinerated because it may be contaminated with radiation. And the incinerated ash must be stored for a long time as a radiation-containing substance.
For this reason, in the curing film for nuclear facilities, when a general phosphorus flame retardant or halogen flame retardant is used as a flame retardant, the combustion product erodes the furnace, and thus its use is limited. Furthermore, in order to suppress the generation amount of residual ash after incineration, a film that does not use as much inorganic flame retardants as magnesium hydroxide is desirable.

  In order to impart flame retardancy to a film without using these flame retardants (phosphorus, halogen and inorganic flame retardants), Japanese Patent Publication No. 58-25379 adds melamine cyanurate to a polyamide resin. A method has been proposed. However, since the film made of polyamide resin is hard, it is inconvenient to construct on a floor or a wall, and it is slippery. Therefore, when it is used on a floor, there are problems in terms of safety.

On the other hand, Japanese Patent Application Laid-Open No. 5-98150 describes a film by inflation molding in which a thermoplastic urethane resin and melamine cyanurate are blended.
However, although the thermoplastic urethane resin is excellent in flame retardancy and flexibility, blocking between films is likely to occur. In order to prevent this blocking, it is necessary to take measures such as sandwiching a release paper between films or adding an additive for preventing blocking. However, when the urethane resin film is subjected to inflation molding, there is a problem that the operation of sandwiching the release paper becomes complicated, and it takes time to develop the effect of the additive.

In addition, when such a urethane resin is formed into a film by a conventional inflation molding machine for olefin resin, the resin adheres to the die outlet due to heat generation of the resin (hereinafter referred to as “eye”). Stable production is not possible.
Therefore, in order to mold a film containing this urethane resin, the screw shape and the die must be changed, special equipment improvements are required, and it is difficult to use the molding machine together with the olefin resin or the like. There was also a problem.

Further, Japanese Patent Application No. 2003-99891 by the present applicant proposes a film having a structure in which a thermoplastic urethane resin is used as an intermediate layer and outer layers made of a polyolefin resin are provided on both sides thereof.
However, the polyolefin resin has a high calorie burn and may damage the furnace during incineration, and because it does not have good adhesion with the urethane resin constituting the middle layer, it is likely to cause delamination after film formation There was a problem.
Japanese Patent Publication No.58-25379 JP-A-5-98150 Japanese Patent Application No. 2003-99891

  In consideration of the above points, the present invention uses a thermoplastic urethane resin, has not only flame retardancy but also has sufficient physical properties at the time of use and construction and excellent transparency without causing a change in color tone. It is an object of the present invention to provide a curing film for a nuclear facility that can be produced on an existing inflation molding machine.

  As a result of repeated studies to solve the above-mentioned problems, the present inventors made a film mainly composed of a thermoplastic polyurethane resin into an intermediate layer, and formed an outer layer made of a resin having good adhesion with the urethane resin on both sides thereof. By using a film with a three-layer structure, it is possible to obtain excellent flame retardancy and blocking resistance as a curing film for nuclear facilities, and molding without special improvement even in a two-kind three-layer inflation molding machine As a result, the present invention has been completed.

That is, the present invention provides a three-layer curing film for a nuclear facility, wherein the middle layer is a layer comprising a composition comprising 100 parts by weight of a thermoplastic polyurethane resin and 10 to 50 parts by weight of melamine cyanurate, The outer layer formed on both sides is a layer made of a composition containing 100 parts by weight of polybutylene adipate terephthalate (hereinafter also referred to as “polyester resin”) and 0 to 50 parts by weight of melamine cyanurate. The gist of the curing film for nuclear facilities.

The curing film for nuclear facilities of the present invention has a laminated structure comprising an intermediate layer mainly composed of a thermoplastic polyurethane resin (hereinafter also simply referred to as “urethane resin”) and an outer layer mainly composed of a polyester resin formed on both surfaces thereof. Is the body.
By forming such a laminated structure, (a) the occurrence of blocking, (b) the urethane resin is soft, which is a problem caused by molding the urethane resin as a single-layer film. Inflation molding is not possible with a single layer because of the occurrence of, and (c) urethane resin deteriorates with ultraviolet rays, so it is easily yellowed by light, and the molded film changes color tone, etc. Can be prevented.

In other words, by forming the outer layer made of polyester resin on both sides of the thermoplastic polyurethane resin as the middle layer, blocking resistance is improved, and production by the current inflation molding machine is possible without causing eye stains. In addition, since yellowing due to light can be prevented, the color tone of the film is maintained for a long period of time.
Also, in order to blow-mold urethane resin, it is possible to mold with a two-type two-layer structure, but in a two-type two-layer film, if the resin characteristics of both layers are different, the curl of the film may be In the present invention, a urethane resin is used as the middle layer of the two-kind / three-layer structure, and a polyester resin is used as both outer layers thereof because it tends to occur and may impair workability during use.

As the thermoplastic polyurethane resin constituting the middle layer, a general polyurethane resin such as a polyester urethane resin, a polyether urethane resin, or a polycarbonate urethane resin can be used.
Any of these polyester-based, polyether-based, or polycarbonate-based urethane resins may be used alone or in admixture of two or more by an appropriate combination.

As a polyester resin constituting the outer layer ,
For example, (1) aliphatic dihydroxy compound (ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, cyclopentane diol, cyclohexane diol, cyclohexane dimethanol, one or more, such as decamethylene glycol) and Aliphatic or aromatic dicarboxylic acids (succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, octadecanedicarboxylic acid, dimer acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, 1 type or 2 types of copolymers, such as naphthalene dicarboxylic acid, (2) Cyclic ester (竈 -propiolactone, 竈 -methyl- 竈 -propiolactone, 艟 -valerolactone, 蛩 -caprolactone, Ring-opening polymerization of one or more of cosides, lactides and the like and copolymers thereof, (3) hydroxycarboxylic acids (glycolic acid, lactic acid, 6-hydroxyhexanoic acid, p-hydroxybenzoic acid, etc.) In the present invention, since the dynamic friction coefficient of the surface of the formed film is large, walking on the film at the time of film construction or use is possible. Polybutylene adipate terephthalate (PBAT) is used because it is difficult to slip .

Polybutylene adipate terephthalate has excellent adhesion to the thermoplastic polyurethane resin that forms the middle layer, and a two-layer / three-layer coextrusion inflation molding results in a three-layer film. It is possible to obtain a laminated film that does not require use and therefore does not cause a decrease in transparency. Moreover, this copolymer does not require the addition of a strong flame retardant such as a halogen-based resin as a component of a flame retardant film, and has a low calorie burn. It also has the advantage that the furnace is not damaged during the incineration of the steel.

This polybutylene adipate terephthalate (hereinafter sometimes abbreviated as “PBAT”) is composed of a copolymer of 1,4-butanediol, terephthalic acid and adipic acid.
PBAT has biodegradability and is excellent in physical properties, flexibility and flame retardancy.
For this reason, when PBAT is used as the polyester resin constituting the outer layer, sufficient flame retardancy can be obtained only by mixing melamine cyanurate without using a flame retardant such as phosphorus, halogen and inorganic. be able to. Moreover, when using it for a floor surface etc., it is better that it is not slippery from the viewpoint of safety, and PBAT is the least slippery among the above-mentioned points.

  Melamine cyanurate added to both the middle and outer layers is a powdered product of the reaction product of melamine and cyanuric acid. It has a large amount of nitrogen atoms in its structure and has a high temperature of about 350 ° C or higher. When it is exposed to, it generates nitrogen gas and inhibits combustion. There are two tautomers of cyanuric acid, enol type and keto type, but in the present invention, those produced by reaction from either of them may be used, and the commonly used melamine cyanurate should be used. Can do.

  The melamine cyanurate preferably has an average particle size of 10 μm or less in order to improve dispersibility in a thermoplastic polyurethane resin or polyester resin and to make the flame retardancy of the film itself uniform. In order to further improve the dispersibility in the resin, a melamine cyanurate surface treated with polyvinyl alcohol or the like may be used.

The addition amount of melamine cyanurate in the middle layer is preferably 10 to 50 parts by weight with respect to 100 parts by weight of the thermoplastic polyurethane resin from the viewpoint of the layer thickness ratio balance with the outer layer and flame retardancy.
If it is less than 10 parts by weight, sufficient flame retardancy cannot be imparted to the thermoplastic polyurethane resin. On the other hand, if it exceeds 50 parts by weight, the flame retardant effect is saturated, the cost is increased, and the melt elongation is reduced, so that not only the film is cut during inflation molding, but the total calorific value is lowered. In the case of incineration, combustion assistance with a burner or the like is required, which is not preferable.

The addition amount of melamine cyanurate in the outer layer is preferably 0 to 50 parts by weight with respect to 100 parts by weight of the polyester resin from the viewpoint of the layer thickness ratio balance with the middle layer and flame retardancy.
The addition amount of melamine cyanurate can be set to 0 (zero) by selecting a resin having excellent flame retardancy such as the aforementioned PBAT as the polyester resin as the main component of the outer layer. On the other hand, if it exceeds 50 parts by weight, there is a possibility that problems may occur during inflation molding or incineration, as in the case of the middle layer.

  In the curing film for nuclear facilities of the present invention, it is possible to add a general phosphorus flame retardant, halogen flame retardant, inorganic flame retardant, etc. other than melamine cyanurate, as described above. It is preferable to avoid the use of flame retardants other than melamine cyanurate due to problems that occur during incineration (furnace erosion, residual ash production, etc.).

Further, in the present invention, in addition to this melamine cyanurate, if necessary, an antistatic agent, a light stabilizer, an ultraviolet absorber, an antioxidant, a plasticizer, a lubricant, Various additives such as a colorant, an inorganic filler, and an organic filler can be appropriately added.
As these antistatic agents, light stabilizers, ultraviolet absorbers, antioxidants, plasticizers, lubricants, colorants, inorganic fillers, organic fillers, and the like, those commonly used in general films can be used.

  Although the thickness of the curing film for nuclear facilities by this invention is not specifically limited, 5-500 micrometers is preferable with the total thickness of three layers. When the thickness is less than 5 μm, not only sufficient strength cannot be obtained, but also the flame retardancy tends to be lowered. When the thickness exceeds 500 μm, workability during handling due to weight increase is lowered.

And in the curing film for nuclear facilities consisting of three layers of the present invention, the thickness ratio between the middle layer and the outer layer is not particularly limited, but from the viewpoint of flexibility, moldability, flame retardancy, total calorific value, etc. : Middle layer: Outer layer = 2: 1: 2 to 1: 4: 1 are preferable.
If the outer layer has a thickness more than twice the thickness of the middle layer mainly composed of thermoplastic polyurethane resin, the total calorific value becomes too low, causing problems such as remaining unburned during incineration. In addition, if the thickness of the middle layer is more than 4 times the thickness of the outer layer, it will become too soft, and it will be easy for the eyes to die at the die outlet in the current inflation molding machine, resulting in lower molding efficiency. There is a possibility of inviting.

  The curing film for nuclear facilities according to the present invention can be produced by a coextrusion inflation method using an existing olefin inflation molding machine without any new equipment improvement, but is not limited thereto. In addition, it is also possible to use a molding method such as a multi-layer coextrusion molding method that has been conventionally used. In any method, each layer can be molded at the same time as each layer can be bonded, so there is no need for an adhesive or adhesive layer to adhere each layer, and therefore the flexibility of the film itself is maintained well. Is done.

The curing film for nuclear facilities of the present invention obtained in this way can be processed with excellent processability in the current inflation molding machine in spite of blending the thermoplastic urethane resin, and is excellent. It has flame retardancy, flexibility (workability), physical properties and transparency.
As specific flame retardancy, in the present invention, it is preferably VTM-0 or higher when measured by the VTM method based on UL94.
As physical properties, it is preferable that the tensile fracture elongation according to the measurement of JIS K 7121 is 300 to 1200%, or the Elmendorf tear strength according to the measurement of JIS K 7128-2 is 200 N / cm or more.

  The curing film for nuclear facilities of the present invention is excellent not only in flame retardancy and workability (or flexibility) but also in physical properties, transparency, and blocking resistance. It can be widely used as a film for covering and partitioning on floors, walls, ceilings, or equipment such as computers and precision instruments, as well as in facilities that handle radioactive materials. In particular, since it does not contain phosphorus-based, halogen-based and inorganic flame retardants, it is effective when used as a curing film for nuclear facilities that are finally incinerated.

  Moreover, since this curing film for nuclear facilities can be satisfactorily produced in the current inflation molding machine despite the blending of the thermoplastic urethane resin, investment for equipment improvement and the like is unnecessary.

[Study 1]
Examples 1-6, Comparative Examples 1-5
For the middle layer, a thermoplastic polyurethane resin (trade name “Esten 58300” manufactured by BF Goodrich) and melamine cyanurate (trade name “MC610” manufactured by Nissan Chemical Co., Ltd.) are mixed at a blending ratio shown in Table 1, and the composition is mixed. Prepared.
On the other hand, for the outer layer, polybutylene adipate terephthalate (trade name “Ecoflex” manufactured by BASF) and melamine cyanurate (similar to those used for the middle layer) were mixed at the blending ratio shown in Table 1 to prepare a composition. .
The prepared composition was put into an extruder for the middle layer and an extruder for the outer layer, respectively, and the thickness ratio of each layer was determined by using a two-kind / three-layer inflation molding machine having a screw having a diameter of 40 mm and a die having a diameter of 100 mm. : Middle layer: Outer layer = 1: 2: 1 A three-layer film having a width of 100 cm and a thickness of 0.1 mm was formed.

  The moldability, flame retardancy, physical properties and blocking resistance of the obtained film were evaluated by the following evaluation methods. The results are shown in Table 1.

(1) Formability: Molding was performed with the current inflation molding machine, and the suitability of molding, the interlayer state after molding, and the like were observed.
(2) Flame retardancy: Measured by the UL94 VTM method and indicated by “VTM-0”, “VTM-1”, “VTM-2” in accordance with the evaluation method of the UL94 VTM method. In addition, a flame retardance is inferior in order of "VTM-0", "VTM-1", and "VTM-2".
(3) Physical properties (tensile fracture elongation and Elmendorf tear strength): Tensile fracture elongation was measured according to JIS K 7121, and Elmendorf tear strength was measured according to JIS K 7128-2.
(4) Evaluation criteria for blocking resistance: The film immediately after molding was wound up in a roll shape and allowed to stand for 1 week at room temperature and normal pressure, then rewound 10 m, and evaluated according to the following criteria.
A: No blocking occurs and rewinding work can be performed smoothly.
○: Slight blocking occurred at a position of less than 10, but there was no adverse effect on the rewinding work and the product film.
X: Generation | occurrence | production of blocking is remarkable and a film cut | disconnect generate | occur | produces during a rewinding operation | work, or a rewinding operation | work can be done, but many adhesions of the broken film piece are seen on the film.

Abbreviations in Table 1 are as follows.
TPU: Thermoplastic polyurethane resin (trade name “Esten 58300” manufactured by BF Goodrich)
MC: Melamine cyanurate (trade name “MC610” manufactured by Nissan Chemical Co., Ltd.)
PBAT: Polybutylene adipate terephthalate (trade name “Ecoflex” manufactured by BASF)
PE: Low density polyethylene (trade name “Petrocene 176” manufactured by Tosoh Corporation)

For Comparative Examples 1, 3, and 4, it was impossible to form a laminated film by an inflation molding machine, and for Comparative Example 5, delamination occurred immediately after film formation. It was impossible to measure the characteristics.
In addition, “drip ignition” in the remarks column in Comparative Example 2 indicates that the absorbent cotton placed under the sample ignited by the melt or the combustion product during the flame retardancy evaluation test (VTM test). Yes.

[Study 2]
(Examination of the type of polyester resin used for the outer layer)
Comparative Examples 7-11
In Example 3, the same procedure as in Example 3 was performed except that the polyester resin shown in Table 2 was used instead of PBAT (polybutylene adipate terephthalate) which is the main component of the outer layer.
The flame retardancy and delamination between the middle layer and the outer layer were evaluated by the following evaluation methods. The results are shown in Table 2.

(1) Flame retardancy: the same as in Example 3.
(2) Interlaminar peelability: The peelability was examined by applying a gum tape to the obtained film surface and peeling off. The case where no peeling was observed was indicated by “◯”, and the case where peeling was indicated by “x”.
(3) Coefficient of dynamic friction: According to the measurement of JIS K 7125, the friction between the obtained films was measured.

Abbreviations in Table 2 are as follows.
TPU: Same as Table 1.
MC: Same as Table 1.
PBAT: Same as Table 1.
PET: Polyethylene terephthalate (trade name “Dianite MA-530H” manufactured by Mitsubishi Rayon Co., Ltd.)
PBT: Polybutylene terephthalate (trade name “Novaduran 5020S” manufactured by Mitsubishi Engineering Plastics)
PBS: Polybutylene succinate (trade name “Bionore # 1001” manufactured by Showa Polymer Co., Ltd.)

[Study 3]
(Examination of more preferable outer layer / middle layer / outer layer ratio)
Examples 12-15
Example 3 was carried out in the same manner as Example 3 except that the thickness ratio of each layer (outer layer: middle layer: outer layer) was changed as shown in Table 3.
The moldability, flame retardancy and total calorific value of the obtained film were evaluated by the following evaluation methods. The results are shown in Table 3.

(1) Formability: as in Example 3 (2) Flame retardancy: as in Example 3.
(3) Total calorific value: Measured by JIS M 8814 thermal laboratory automatic cylinder calorimeter method.
The abbreviations in Table 3 are the same as those in Table 1.

The curing film for nuclear facilities of the present invention is blended with a thermoplastic urethane resin, has not only flame retardancy but also sufficient physical properties at the time of use and construction, and excellent transparency without color change. Therefore, not only in facilities that handle radioactive materials, such as nuclear power plants and nuclear research laboratories, but also in general construction sites, etc., coating films for equipment such as floors, walls and ceilings, or computers and precision equipment, It can also be suitably used as a partition film.
In addition, this curing film for nuclear facilities can be produced on the current inflation molding machine without the need for special equipment improvement or new equipment investment in spite of blending thermoplastic urethane resin. Is.

Claims (1)

In the curing film for nuclear facilities consisting of three layers,
The middle layer is a layer made of a composition containing 100 parts by weight of a thermoplastic polyurethane resin and 10 to 50 parts by weight of melamine cyanurate,
A curing film for a nuclear facility, wherein the outer layers formed on both surfaces of the middle layer are layers comprising a composition containing 100 parts by weight of polybutylene adipate terephthalate and 0 to 50 parts by weight of melamine cyanurate.