JPH0574615B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention has high heat resistance, that is, a high heat distortion temperature,
The present invention also relates to a flame-retardant ethylene-ethyl acrylate copolymer composition having excellent mechanical strength. (Prior Art) It is well known that polyolefins are suitable for wire insulation, cable sheathing, and other applications due to their mechanical strength, water resistance, chemical resistance, and their outstanding electrical properties. be. However, polyolefins are easily flammable, and flame retardation is required in the above-mentioned applications. Conventionally, halogen-based flame retardants or a mixture of the halogen-based flame retardants and antimony oxide have been most commonly used to make polyolefin flame retardant, but when heated and burned, a large amount of highly toxic halogen gas and smoke are released. The problem is that it is not only harmful to the human body, but also corrodes surrounding equipment due to its corrosive nature. On the other hand, it is well known that inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide are effective as low-smoke flame retardants that do not generate harmful gases during flame retardation. In addition, when using the above inorganic flame retardants, oxygen-containing resins such as ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) and ethylene-ethyl acrylate copolymer (hereinafter referred to as EEA) are used as the polyolefin. It is also known that a additive flame retardant effect can be obtained when used in combination with a flame retardant effect. Among them
EEA is superior to EVA in terms of heat resistance, low-temperature properties, electrical properties, etc., and in recent years demand for advanced flame retardancy has been met, and demand is rapidly increasing. (These techniques include, for example, JP-A No. 51-132254, JP-A No. 56-136832, JP-A No. 60-
There are issues such as No. 13832. ) However, conventionally, commercially available
In EEA, when the content of ethyl acrylate (hereinafter referred to as EA) is increased in order to improve flame retardant performance and improve receptivity to inorganic metal compounds that are flame retardants, the degree of crystallinity decreases significantly, resulting in a decrease in mechanical strength and heat resistance. It has the disadvantage that the deformation temperature decreases, making it impractical. On the other hand, when the EA content is reduced, the acceptability of inorganic metal compounds deteriorates, and the amount of inorganic metal compounds added is naturally limited, resulting in deterioration of low-temperature properties and flame retardancy. As mentioned above, although EEA is preferable as a non-polluting flame retardant resin with the addition of inorganic flame retardants, conventional EEA has been used to improve mechanical strength and heat resistance in recent years, where a high degree of flame retardancy is required. It is difficult to say that I am fully satisfied with these points. (Problems to be Solved by the Invention) In view of the above points, the present invention provides a flame-retardant composition that has particularly excellent heat resistance, mechanical strength, and low-temperature properties, is low in smoke, and is non-polluting. This flame-retardant composition is used for molding purposes such as electric wires, cables, packing, sealing materials, holes, films, and injection molded products, and as master batches. (Means for Solving the Problems) The present invention is characterized in that an inorganic flame retardant is added to 100 parts by weight of a resin component whose main component is an ethylene-ethyl acrylate copolymer.
In a composition comprising 40 to 150 parts by weight of the ethylene-ethyl acrylate copolymer, (a) a melt index of 0.2 to 5 g/10 min, and (b) a content of ethyl acrylate of 10 to 20 (c) a flame-retardant ethylene-ethyl acrylate copolymer in which the relationship between the content (E) of ethyl acrylate and the melting point (T) satisfies the following formula: T≧-0.8×E+109; A combined composition is provided. The ethylene-ethyl acrylate copolymer of the present invention has an ethyl acrylate content of 10 to 20% by weight and a melt index (hereinafter referred to as MI).
is in the range of 0.2 to 5 g/10 min, and the relationship between the ethyl acrylate content (E) and the melting point (T) of the resin satisfies the following formula T≧-0.8×E+109, which is a specific range. is necessary. If the above-mentioned MI is less than 0.2 g/10 minutes, workability deteriorates, and if it exceeds 5 g/10 minutes, strength decreases. A particularly preferred MI ranges from 0.5 to 2 g/10 minutes. Furthermore, if the EA content is less than 10% by weight, when an amount sufficient to make the inorganic metal compound described below flame retardant is added, the mechanical strength will be significantly reduced and the low-temperature properties will be deteriorated. On the other hand, if it exceeds 20% by weight, the melting point will drop significantly, the heat distortion temperature will become low, and there will be no heat resistance. In view of the above, a particularly preferred EA content is in the range of 14 to 17% by weight. Furthermore, in the present invention, the relationship between the EA content (E) and the melting point (T) of EEA, that is, the formula T≧−0.8×E+
By satisfying 109, it is essentially distinguished from conventional EEA, and by limiting the EA content to the above-mentioned specific range, it becomes a composition that can meet the recent strict demands for flame retardancy. It is. Positive, <melting point> is differential scanning calorimetry (DSC)
The maximum peak temperature (Tm) is measured as follows: In other words, accurately weigh approximately 5 mg of sample, and
Set it on DSC, raise the temperature to 170℃, and at that temperature
After holding for 15 minutes, cool to room temperature at a rate of 10°C/min. Next, from this state, at a speed of 10℃/min.
The measurement is completed by increasing the temperature to 170℃. The maximum peak temperature (Tm) is expressed by the temperature at the top of the maximum peak that appears during the temperature increase from 0°C to 170°C. <EA content> is determined from the absorbance at 860 cm ^-1 attributed to EA by infrared absorption spectrum (IR). However, the calibration curve is determined by determining the EA concentration using nuclear magnetic resonance spectroscopy (NMR) and by correlating it with the absorbance at 860 cm ^-1 of IR. The EEA of the present invention, which satisfies the above relational expression between EA content (E) and melting point, was developed by the present inventors as a result of intensive studies to satisfy the above strict requirements. It is manufactured under the EEA system and is structurally different from the previously proposed EEA. That is, as shown in FIG. 1, the EEA of the present invention has the formula T in the relationship between the EA content and the melting point.
≧−0.8×E+109 line or higher, and the EA content is 10 to 10 to maintain high flame retardant properties.
The amount is limited to 20% by weight. On the other hand, the previously proposed EEA is the above T≧−0.8×E+109
Exists below the line. The reason for this is not yet clear, but it is speculated that the structure is different due to the distribution state of the EA group introduced into the ethylene polymer chain. Inorganic flame retardants of the present invention include aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, basic magnesium carbonate, dolomite, hydrotalcite, calcium hydroxide, barium hydroxide, tin oxide hydrate, borax, etc. Hydrates of inorganic metal compounds, zinc borate, zinc metaborate, barium metaborate, zinc carbonate, magnesium-calcium carbonate, calcium carbonate, barium carbonate, magnesium oxide, molybdenum oxide, zirconium oxide, tin oxide, antimony oxide, red Examples include phosphorus. These may be used alone or in combination of two or more. Among these, at least one selected from the group consisting of magnesium hydroxide, aluminum hydroxide, basic magnesium carbonate, and hydrotalcite has a good flame retardant effect and is economically advantageous. The particle size of these flame retardants varies depending on the type, but for magnesium hydroxide, aluminum hydroxide, etc., the average particle size is preferably 20 μm or less. The above amount of inorganic flame retardant is based on 100 parts by weight of EEA.
It ranges from 40 to 150 parts by weight, preferably from 70 to 120 parts by weight. If the amount of the flame retardant is less than 40% by weight, the flame retardant effect will be small, and if it exceeds 150 parts by weight, the elongation will decrease, the material will become brittle, and the low-temperature properties will also deteriorate. In addition to the above inorganic flame retardants, clay, silica,
There is no problem in using common inorganic fillers such as talc. Furthermore, the surface of the inorganic flame retardant is coated with fatty acids such as stearic acid, oleic acid, and palmitic acid, or metal salts thereof, wax, organic silane, organic borane,
It is preferable to perform a surface treatment such as coating with an organic titanate or the like. In the flame retardant composition of the present invention, other olefinic polymers may be added to the extent that they do not impair the characteristics of the present invention.
For example, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-unsaturated carboxylic acid ester copolymers other than the scope of the present invention, high-, medium-, and low-density Ethylene homopolymer or ethylene and propylene, butene-1, pentene-1, hexene-1,
Copolymers with α-olefins having 3 to 12 carbon atoms such as 4-methylpentene-1, octene-1, and decene-1, propylene homopolymers, or copolymers of propylene and other α-olefins, or Polymers obtained by modifying ethylene or propylene homopolymers or copolymers containing ethylene or propylene as a main component with other α-olefins with unsaturated carboxylic acids such as acrylic acid or maleic acid or derivatives thereof, and mixtures thereof, etc. There is no problem in adding. Furthermore, in the present invention, in order to improve the flame retardant effect, the inorganic flame retardant may be used in combination with a small amount of an organic flame retardant such as a halogen flame retardant or a phosphorus flame retardant, or a flame retardant aid. Further, conventional additives such as various stabilizers such as antioxidants, ultraviolet absorbers, and copper damage inhibitors, pigments, crosslinking agents, crosslinking aids, blowing agents, and nucleating agents may be added. (Operations and Effects of the Invention) As described above, the flame retardant composition of the present invention does not generate harmful gases during flame retardation, has low smoke properties, is non-polluting, and is superior to conventional flame retardant EEA. Cables with excellent heat resistance and mechanical strength are used for various power generation plants including nuclear power research institutes, which have regulated amounts of corrosive gases, cables for chemical, steel, and petroleum plants, fire-resistant electric wires, and general indoor wiring. It is suitable for use in places where a high degree of flame retardancy is required. It can also be used for molding purposes such as films, sheets, pipes, and injection molded products, and as a master batch. Examples 1 to 7 and Comparative Examples 1 to 7 <Manufacture of EEA resin> Using a tubular reactor, in the presence of an initiator and a chain transfer agent, a pressure of 2500 to 3000 Kg/
Ethylene and ethyl acrylate were radically copolymerized under conditions of cm ² and temperature of around 250°C to produce various EEAs as shown in Table 1. Add a specified amount of magnesium hydroxide (product name: Kisuma 5B, manufactured by Kyowa Kagaku Co., Ltd.) to 100 parts by weight of each of the above EEAs and an antioxidant (product name: Santonox R,
(manufactured by Yoshitomi Pharmaceutical Co., Ltd.) was uniformly kneaded in a Plastograph set at 200°C. The tensile strength, heat deformation rate, embrittlement temperature, and oxygen index of this composition were measured, and the results are shown in Table 1 (Example 1
-6, Comparative Examples 1-5). Table 1 shows the results of evaluation in the same manner as in Example 1, using aluminum hydroxide instead of magnesium hydroxide, which is the flame retardant in Example 1 (Example 7). Table 1 also shows the results of evaluation using a commercially available EEA in the same manner as in Example 1 (Comparative Example 6 used Nippon Unicar's product name DPDJ6182, and Comparative Example 7 used Mitsui Polychemical's product name A702. example). <Test method> 1 Tensile strength and elongation A test piece was punched out from a sheet with a thickness of 1 m/m using a No. 3 dumbbell, and the tensile speed was adjusted using a Tensilon.
Measurements were made at a speed of 200 mm/min. 2 Heating deformation rate A cylinder with a thickness of 6 m/m and a diameter of 10 m/m was immersed in an oil bath at 90°C, pressurized with a load of 1.02 kg, and the deformation rate was determined after 30 minutes. 3 Brittleness temperature Compliant with ASTMD746 4 Oxygen index Compliant with JISK7201

[Table] Note: Underlining indicates that it is outside the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between ethyl acrylate (EA) content and melting point in an ethylene-ethyl acrylate copolymer.

Claims (1)

[Claims] 1. 40 to 150 parts by weight of an inorganic flame retardant to 100 parts by weight of a resin component whose main component is an ethylene-ethyl acrylate copolymer.
parts by weight, the ethylene-ethyl acrylate copolymer has (a) a melt index of 0.2 to 5 g/10 min, and (b) an ethyl acrylate content in the range of 10 to 20% by weight. and (c) a flame-retardant ethylene-ethyl acrylate copolymer composition in which the relationship between the content (E) of ethyl acrylate and the melting point (T) satisfies the following formula: T≧−0.8×E+109. 2. The flame-retardant ethylene-ethyl acrylate copolymer composition according to claim 1, wherein the inorganic flame retardant is a hydrate of an inorganic metal compound. 3. The flame-retardant ethylene-ethyl acrylate copolymer composition according to claim 2, wherein the hydrate of the inorganic metal compound is aluminum hydroxide or magnesium hydroxide.