JP4117151B2 - Flame retardant sheet - Google Patents

Description

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【表２】

【００６３】
【表３】

【００６４】
【発明の効果】
本発明の難燃性シートの構成は前述の通りである。メラミン、特定の脂肪酸アミド、特定の樹脂を特定の割合で組み合わせることにより、ＵＬ−９４ ＶＴＭ−０に相当する高度の難燃性を有しながら、物性に優れ、加工しやすく、燃焼時に有害なガスの発生が無く、灰分もほとんど無く、特に放射線物質取扱所において好適に使用できるシートが安価に得られる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flame-retardant sheet excellent in flame retardancy, excellent in sheet processability and sheet physical properties, generating little harmful gases and harmful substances even when incinerated, and having little residual ash content. It is about.
[0002]
[Prior art]
When a radiation handling device is inspected at a place where radioactive materials such as chemical factories, research laboratories, hospitals, and nuclear power plants are handled, the device and its surroundings must be covered with a sheet to protect it from contamination. Has been done.
[0003]
This seat covers the removed equipment and the like to ensure safety during construction, prevent contamination, and lay down in passages and work spaces to move workers and perform maintenance work on the seat. It may also be used as a protective clothing fabric to protect workers.
[0004]
Fire may be used for fusing, welding, etc. due to construction work in the surrounding area, and there are many facilities that cause a great risk of fire occurrence, so the seat used for this purpose must have a high degree of flame retardancy. In addition, flame retardancy corresponding to VTM-0 is required in a flame retardancy test based on UL-94 as a flame retardancy standard.
[0005]
Conventionally, ethylene-vinyl acetate resin and vinyl chloride resin have been used as protective sheets, and inorganic materials such as aluminum hydroxide, magnesium hydroxide, antimony oxide, and melamine phosphate are used to impart flame retardancy to the sheet. A flame retardant was used.
[0006]
These protective sheets are removed and incinerated after the completion of the predetermined work, but the residual ash contains radioactive substances, so it must be put in a special container and landfilled. In addition, if halogen-based resin sheets or flame retardants containing halogens are used, toxic gases and harmful substances are generated during incineration, which damages the incinerator and adversely affects the surrounding environment. No flame retardant resin sheet was required.
In addition, since elements such as phosphorus and halogen become radioisotopes, it is required that the target sheet does not contain elements that easily become radioisotopes such as phosphorus and halogen.
[0007]
Therefore, a film in which an organic flame retardant such as melamine cyanurate is added to a polyamide resin or an olefin resin has been proposed (Japanese Patent Laid-Open Nos. 2001-31780 and 2001-206961). However, although these films satisfy the above-mentioned requirements for post-treatment properties, the actual situation is that the flame retardancy is not necessarily sufficient, and if the amount of the flame retardant is increased in order to have sufficient flame retardancy, Since film processability and film strength must be sacrificed and the price of the flame retardant is also expensive, further improvement has been desired.
[0008]
In addition, in Japanese Patent Application No. 2002-099182, a flame retardant film composed of melamine and a fatty acid was proposed. Although the film has sufficient flame retardancy and post-treatment properties, white streaks occur during sheet molding when continuously formed in large quantities. In addition, unevenness in thickness is likely to occur, which is insufficient in terms of film formability.
[0009]
[Problems to be solved by the invention]
The present invention is intended to solve the above-mentioned problems of the prior art, and is excellent in flame retardancy, film elongation, strength, film formability and thickness unevenness during mass production of sheets, and workability. It is to provide an inexpensive flame retardant which is excellent and easy in post-processing.
[0010]
[Means for Solving the Problems]
In order to solve the aforementioned problems, a flame retardant sheet comprising 100 parts by weight of melamine, 2 to 20 parts by weight of a fatty acid amide having 12 to 24 carbon atoms, and 50 to 150 parts by weight of an olefin resin containing an elastomer component is provided. Yes,
[0011]
Preferably, the olefin resin provides the flame retardant sheet which is a polypropylene resin,
[0012]
The olefin-based resin provides the flame-retardant sheet, which is an ethylene-propylene copolymer elastomer-containing polypropylene containing an elastomer component,
[0013]
Preferably, the flame retardant sheet in which the fatty acid amide is stearamide is provided.
[0014]
Preferably, the flame retardant sheet having a particle size of melamine of 10 μm or less is provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
The flame retardant sheet in the present invention is made of an olefin resin. Considering the ease of forming a sheet and the processing of the sheet after disposal, a polyolefin-based resin that does not generate harmful substances during incineration is preferable.
[0016]
The polyolefin resin is not particularly limited as long as it is a polyolefin resin that can be formed into a sheet without impairing flame retardancy and sheet formability, but includes polyolefin resins and modified olefin resins.
[0017]
The narrowly defined polyolefin resin is a low crystal or high crystallinity resin obtained by polymerization or copolymerization mainly of an olefin having 2 to 8 carbon atoms, and is a very low density polyethylene (hereinafter sometimes abbreviated as VLDPE). , Low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), polypropylene (PP), atactic polypropylene, polybutene-1 (PB-1) and the like.
[0018]
The modified olefin resin referred to here refers to a resin obtained by copolymerization of olefin and a monomer other than olefin within a range not inhibiting the generation of negative ions. Examples of the olefin monomer include ethylene, propylene, butene, butadiene, isoprene, hexene, heptene, octene and the like, and examples of the monomer to be copolymerized include EPM, EPDM, styrene, alkyl styrene, vinyl ether and the like.
[0019]
Among the polyolefin-based resins, ethylene-propylene copolymer elastomers (EPM, EPDM) and polypropylene-polyethylene (PP-PE) random copolymers are preferable from the viewpoint of stable productivity at the time of continuous molding. In view of improvement of generation and unevenness of thickness, PP-PE random copolymer is particularly preferable.
[0020]
Also, considering the moldability of sheeting among the polyolefin resins, ultra low density polyethylene, linear low density polyethylene, low density polyethylene, high density polyethylene, polypropylene, polybutene-1, styrene-olefin copolymer resins At least one kind of resin composition selected from among them is also preferably used. Among them, a polypropylene-based resin containing polypropylene as a main constituent is excellent in flame retardancy and moldability and is preferably used.
[0021]
In addition to the polyolefin-based resin, the resin of the present invention may contain other resins in a range that does not hinder flame retardancy and sheet formability. Examples of resins that can be mixed include (meth) acrylic acid ester resins, styrene resins, urethane resins, polyester resins, polyoxyethylene resins, polyamide resins, and the like.
[0022]
The flame retardant sheet in the present invention can also use a polypropylene resin containing an elastomer component.
The elastomer component is not particularly limited as long as it has properties as an elastomer. For example, styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene -Styrene-containing elastomers such as butadiene-styrene block copolymer (SBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), hydrogenated styrene-butadiene random copolymer (HSBR), and 1,2- There are polybutadiene elastomer (RB), trans 1,4-polyisoprene elastomer (TPI), ethylene-propylene copolymer elastomer (EPM, EPDM), polyisobutylene, polyethylene-polybutylene, and the like.
[0023]
With respect to polypropylene, a certain amount of high molecular weight atactic body can be formed by controlling stereoregularity during polymerization. This high molecular weight atactic component functions as an elastomer component in the present application, brings about the same effect as blending an elastomer with a single composition polypropylene, and can be suitably used for the sheet of the present invention.
[0024]
Considering the moldability of sheeting and the physical properties of the sheet, polypropylene-based thermoplastic bioelastomer (TPO) is a preferred embodiment.
Depending on the type of TPO, (1) a simple blend type TPO (a thermoplastic polyolefin resin and an elastomeric component such as EPDM are physically blended with a disperser such as Banbury or Plastmill, and a rubber component in an olefin matrix. ), (2) Implant type TPO (Elastomeric polymerization of olefin to form hard segment and soft segment in the reactor in order to give elastomeric properties), (3) Motion Cross-linking type TPO (which is physically mixed with a disperser such as Banbury or Plastomyl and the rubber component is subjected to a cross-linking reaction, and the cross-linked rubber component is finely dispersed in the thermoplastic polyolefin matrix). Any of them can be suitably used.
The flame retardant sheet of the present invention contains melamine as a flame retardant. The melamine used in the present invention is not particularly limited as long as it is a crystal having a purity of 90% or more, and a commercially available product used as a raw material such as a melamine resin may be used.
[0026]
The melamine used in the patented invention preferably has an average particle size of 10 μm or less, and particularly preferably an average particle size of 5 μm or less, considering the dispersibility in the resin and the appearance of the sheet. Accordingly, a powder obtained by further finely pulverizing commercially available melamine crystals can also be suitably used.
[0027]
The pulverization method is not particularly limited, but a ball mill, a roller mill, a bead mill, a hammer mill, a stamp mill or the like can be used, and it is preferable to use a ball mill from the viewpoint of workability. Also, an alumina ball mill is preferable in order to prevent contamination.
[0028]
The content of the resin is 50 to 150 parts by weight, preferably 55 to 140 parts by weight, particularly preferably 60 to 120 parts by weight, based on 100 parts by weight of melamine. If it is 50 parts by weight or more, it is preferable because the elongation and strength of the sheet are sufficient.
[0029]
The flame retardant sheet of the present invention contains a fatty acid amide having 12 to 24 carbon atoms. This fatty acid amide enhances the affinity of melamine to the resin, contributes to improving physical properties such as sheet elongation, and also gives the sheet appropriate softness and tenacity, making it easier to handle the sheet. Also have.
[0030]
The fatty acid amide that can be used in the sheet is not particularly limited as long as it does not contain elements other than carbon, hydrogen, oxygen, and nitrogen. Lauric acid amide, myristic acid amide, bartimic acid amide, stearic acid amide, Saturated fatty acid amides such as isostearic acid amide, arachidic acid amide, behenic acid amide, lignoceric acid amide, adipic acid amide; palmitoleic acid amide, oleic acid amide, linoleic acid amide, linolenic acid amide, elaidic acid amide, celetic acid amide, Elca Examples thereof include unsaturated fatty acid amides such as acid amides, ricinoleic acid amides, phthalic acid amides, and toluic acid amides. Of these, stearamide is most preferable because it is inexpensive, has an appropriate melting point, has little irritation and odor, and is easy to handle.
Unsaturated fatty acid amides such as oleic acid amide are liquid at room temperature and easy to handle, but have poor heat resistance and may cause thermal discoloration during processing. In such a case, for example, a heat stabilizer such as α-tocopherol may be used in combination.
[0031]
The content of the fatty acid amide is 2 to 20 parts by weight, preferably 3 to 15 parts by weight, particularly preferably 5 to 10 parts by weight, based on 100 parts by weight of melamine.
If it is 2 parts by weight or more, the formability and strength of the sheet are sufficient, and if it is 20 parts by weight or less, the flame retardancy is sufficient, it is preferable.
[0032]
In addition to the above resin, the flame retardant sheet has a structure that does not cause inconvenience during incineration, that is, a structure that does not contain elements other than oxygen, hydrogen, carbon, and nitrogen in the molecule (generates harmful radioisotopes) Various additives such as an ultraviolet absorber having a structure that does not contain such an element as a structure), a light stabilizer, and various additives such as an antioxidant may be contained.
[0033]
As the ultraviolet absorber, organic ultraviolet absorbers such as benzophenone, benzotriazole, cyanoacrylate and benzoate can be used.
[0034]
Examples of the light stabilizer include bis (2,2,6,6, -tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6, -pentamethyl-4-piperidyl) sebacate, 1- [ 2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy Hindered amines such as -2,2,6,6, -tetramethylpiperidine, 4-benzoyloxy-2,2,6,6, -tetramethylpiperidine can be used.
[0035]
As the antioxidant, hindered phenol-based, lactone-based, and α-tocopherol-based agents can be used.
The above ultraviolet absorbers, light stabilizers, and antioxidants can be selected and used in combination with high effects, and fluorescent whitening agents such as benzoxazole and stilbene can also be added. You may contain another organic filler for the purpose of improving a flame retardance, a film physical property, etc. Furthermore, you may contain coloring agents, such as a pigment and dye, for the purpose of coloring.
[0036]
A general method may be used for blending the compound into a sheet. For example, as a blending method, melamine and a fatty acid are heated and mixed using a Henschel mixer or the like, then finely pulverized with a ball mill or the like, and biaxial extrusion together with a resin. What is necessary is just to pelletize using a machine etc.
Examples of the sheet forming method include a T-die extrusion method, an inflation method, and a calendar method.
[0037]
The flame retardant sheet of this case is often used as a protective sheet when repairing nuclear facilities, but it can be used to cover disassembled equipment, lay it on the floor, walk on it, or work in some cases. The sheet needs to have mechanical properties (strength, resistance to slipping, etc.), flexibility (easiness to cover, difficulty in tearing, etc.), workability, and the like.
[0038]
The film thickness of the flame retardant sheet is 30 to 300 μm, preferably 35 to 200 μm, more preferably 40 to 150 μm. A film thickness of 30 μm or more is preferred because it has excellent mechanical strength and is less likely to break during use. Moreover, if it is 300 micrometers or less, since it is lightweight and easy to handle and it is advantageous also in terms of cost, it is preferable.
[0039]
The yield stress of the flame retardant sheet is 3 MPa or more, preferably 4 MPa or more, particularly preferably 5 MPa or more, and the flame retardant sheet breaking stress is 4 MPa to 25 MPa, preferably 5 MPa to 20 MPa, particularly preferably 6 MPa to A high-strength sheet having a moderate hardness of 15 MPa is particularly preferable.
[0040]
The yield stress of the flame retardant sheet is 3 MPa or more, preferably 4 MPa or more, particularly preferably 5 MPa or more, and the breaking elongation of the film at that time is 200% or more, preferably 300% or more, particularly preferably 400 It is particularly preferable to use a flame retardant sheet that is at least% and has strength and flexibility.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be described by way of examples.
The physical properties were evaluated by the methods described below.
(1) Appearance of sheet Visual evaluation ○: Good and no defects Δ: Conspicuous flow stripes ×: Significant surface roughness (2) Sheet mechanical properties: The following physical properties were measured based on JIS K7127 .
(1) Yield stress (2) Breaking stress (3) Elongation at break (3) Sheet evaluation ○: Flexible and well stretched, not easily tearable Δ: Slightly stretchable and slightly tearable ×: Crude, practical as a sheet Unbearable (4) Ash content The residue at 850 ° C. was regarded as ash content.
(5) Flame retardance It was carried out by the VTM method based on UL-94.
[0042]
[Example 1]
8 parts by weight of stearamide was added to 100 parts by weight of melamine having an average particle size of 3 μm, and the mixture was stirred with a Henschel mixer, and when the temperature reached 130 ° C. over about 1 hour, the stirring was stopped. After cooling to 50 ° C. for about 8 hours, a polypropylene resin having a PP-PE random copolymer structure as a polypropylene resin is mixed with 90 parts by weight of Sumitomo Nobrene S131 (manufactured by Sumitomo Chemical Co., Ltd.) and the same direction twin screw extruder PCM-30 (manufactured by Ikekai) was kneaded and pelletized at a cylinder temperature of 200 ° C.
The pellet was extruded at a cylinder temperature of 200 ° C. and a die temperature of 190 ° C. using a single-screw extruder with a T-die having a cylinder diameter of 65 mm and L / D 28 to obtain a sheet having a thickness of 130 μm.
[0043]
[Example 2]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that 8 parts by weight of stearamide was changed to 5 parts by weight.
[0044]
[Example 3]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that 8 parts by weight of stearamide was changed to 15 parts by weight.
[0045]
[Example 4]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that the polypropylene resin S131 (manufactured by Sumitomo Chemical) was changed to 60 parts by weight.
[0046]
[Example 5]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that 120 parts by weight of polypropylene resin S131 (Sumitomo Chemical Co., Ltd.) was used.
[0047]
[Example 6]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that 90 parts by weight of polypropylene resin S131 (manufactured by Sumitomo Chemical Co., Ltd.) was used.
[0048]
[Example 7]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that isostearic acid amide was used instead of stearic acid amide.
[0049]
[Example 8]
To 100 parts by weight of melamine having an average particle size of 30 μm, 8 parts by weight of oleic acid amide and 0.5 parts by weight of α-tocopherol were added and pulverized for 5 hours using an alumina ball mill to obtain an average particle size of 5 μm. Subsequently, 90 parts by weight of polypropylene resin S131 (manufactured by Sumitomo Chemical Co., Ltd.) and kneaded and pelletized at a cylinder temperature of 200 ° C. using the same direction twin screw extruder PCM-30 (manufactured by Ikekai)
The pellet was extruded at a cylinder temperature of 200 ° C. and a die temperature of 190 ° C. using a single-screw extruder with a T-die having a cylinder diameter of 65 mm and L / D 28 to obtain a sheet having a thickness of 130 μm.
[0050]
[Example 9]
In the same manner as in Example 8, a sheet having a thickness of 65 μm was obtained.
[0051]
[Example 10]
Except for replacing 90 parts by weight of polypropylene resin S131 (manufactured by Sumitomo Chemical) with 100 parts by weight of in-reactor alloy-polypropylene resin KS-353P (manufactured by MONTEL-JPO) containing an ethylene propylene-based elastomer, the same procedure as in Example 1 was performed. A sheet having a thickness of 130 μm was obtained.
[0052]
Example 11
A sheet having a thickness of 130 μm was prepared in the same manner as in Example 1 except that 90 parts by weight of the polypropylene resin S131 (manufactured by Sumitomo Chemical) was replaced with 100 parts by weight of an elastomer component-containing ethylene-based resin, Tuffmer A-4090 (manufactured by Mitsui Chemicals). Obtained.
[0053]
Example 12
A sheet having a thickness of 130 μm was prepared in the same manner as in Example 1 except that 90 parts by weight of the polypropylene resin S131 (manufactured by Sumitomo Chemical) was replaced with 100 parts by weight of an elastomer component-containing polypropylene resin, Tuffmer XR-106P (manufactured by Mitsui Chemicals). Obtained.
[0054]
[Comparative Example 1]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that stearamide was not used.
[0055]
[Comparative Example 2]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that 1 part by weight of stearamide was used.
[0056]
[Comparative Example 3]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that 25 parts by weight of stearamide was used.
[0057]
[Comparative Example 4]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that 45 parts by weight of polypropylene resin S131 (Sumitomo Chemical Co., Ltd.) was used.
[0058]
[Comparative Example 5]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that 160 parts by weight of polypropylene resin S131 (manufactured by Sumitomo Chemical) was used.
[0059]
[Comparative Example 6]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that melamine having an average particle size of 30 μm was used.
[0060]
[Comparative Example 7]
A sheet having a thickness of 130 μm was obtained in the same manner as in Example 1 except that stearic acid was used instead of stearic acid amide.
[0061]
The above results are summarized in Tables 1 to 3.
[Table 1]

[0062]
[Table 2]

[0063]
[Table 3]

[0064]
【The invention's effect】
The structure of the flame retardant sheet of the present invention is as described above. Combining melamine, specific fatty acid amide, and specific resin in specific proportions, while having high flame retardancy equivalent to UL-94 VTM-0, it has excellent physical properties, is easy to process, and is harmful during combustion There is no generation of gas, almost no ash, and a sheet that can be suitably used particularly at a radioactive material handling station can be obtained at low cost.

Claims (5)

A flame retardant sheet comprising 100 parts by weight of melamine having an average particle size of 10 μm or less, 2 to 20 parts by weight of a fatty acid amide having 12 to 24 carbon atoms, and 50 to 150 parts by weight of an olefin resin , which does not contain phosphorus / halogen , A flame retardant sheet for a radioactive material handling station having an ash content of 0.1% or less and a breakage of 300% or more . The flame retardant sheet according to claim 1, wherein the olefin resin is a polypropylene resin. The flame-retardant sheet according to claim 1, wherein the olefin-based resin is a polypropylene-polyethylene (PP-PE) random copolymer. The flame-retardant sheet according to claim 1, wherein the olefin resin is an ethylene-propylene copolymer elastomer-containing polypropylene containing an elastomer component. The flame retardant sheet according to any one of claims 1 to 4, wherein the fatty acid amide is stearic acid amide.