JPS6144095B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a highly inorganic-filled flame-retardant resin composition with excellent flame retardancy and mechanical properties, and particularly to a highly flame-retardant polyolefin-based resin composition that does not generate corrosive gas during combustion. Polyolefin resins are inexpensive, general-purpose resins that have excellent mechanical properties, electrical properties, etc., and are therefore used in large quantities in many fields. However, with the recent development of a high-density society, there is a trend toward stricter demands for flame retardancy in these resins. It is widely used to make polyolefin resins flame retardant by adding ordinary halogen flame retardants, but in this case, there is a problem in that when burned, a large amount of smoke is generated along with corrosive gases that are harmful to the human body and equipment. be. In order to solve this problem, flame retardant means that do not use halogenated flame retardants are being studied, such as flame retardant methods by highly filling inorganic powders such as hydrated metal oxides. For example, Japanese Patent Publication No. 52-38580 (Japanese Unexamined Patent Publication No. 49-59841) discloses a reactive filler made by coating the surface of a metal hydroxide with a polymerizable organic acid to a predetermined thickness. A flame-retardant composition has been proposed in which a predetermined amount of an organic phosphate ester or an inorganic phosphate compound is mixed into a composition obtained by melt-kneading an organic plastic and heating the mixture. This flame-retardant composition is characterized in that a polymerizable organic acid is reacted with the surface of an inorganic material to obtain a flame-retardant composition with excellent bending properties. Other known examples include putty made of polybutene and melamine phosphate (West German Publication No. 2,621,115), and paper containing melamine phosphate and aluminum hydroxide (Japanese Patent Laid-open Nos. 51-23313 and 51-51).
23312)). These examples relate to the flame retardation of flowable liquid putties and papers made of cellulose. The purpose of the present invention, which is completely different from these conventional known technologies, is to have extremely high flame retardancy and to generate no corrosive gas even if burned.
Another object of the present invention is to obtain a low-smoke flame-retardant resin composition that emits significantly less smoke, and which also maintains the excellent mechanical properties inherent to polyolefin resins. The present invention is characterized in that 80 to 250 parts by weight of hydrated metal oxide powder and 1 to 30 parts by weight of organic phosphate compound powder are uniformly contained in 100 parts by weight of polyethylene resin. This object is achieved by a highly inorganic-filled flame-retardant resin composition. In the present invention, it has been confirmed that flame retardancy is synergistically enhanced by using a hydrated metal oxide and an organic phosphate compound in combination with a polyethylene resin. In other words, by adding a large amount of hydrated metal oxide and a small amount of organic phosphate compound to polyethylene resin, it is possible to achieve the highest flame retardancy in the UL (U.S. Underwriter Laboratory Standard)-94 vertical combustion test. V- is a tough rank.
It was confirmed that the area that can pass the 0 standard can be expanded. Although the mechanism of action of the organic phosphate compound in the present invention is unknown, it has been shown that the addition of a small amount of organic phosphate chloride in the presence of a large amount of hydrated metal oxide improves the resin composition during combustion. It exhibits the effect of significantly reducing melt dripping. As a result, the content of hydrated metal oxide required to pass the V-0 standard in the UL-94 test can be significantly reduced, realizing a flame-retardant resin composition with excellent mechanical properties. be able to. The polyethylene resin used in the present invention is selected from the group consisting of polyethylene and ethylene copolymers. Here, "polyethylene" refers to various types of low-density, medium-density, and high-density polyethylene, and "ethylene copolymers" include, for example, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, Ethylene-α-olefin copolymers such as ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-butene copolymer, etc., ethylene-vinyl acetate-vinyl chloride terpolymer, etc. . As in the present invention, in order to maintain the excellent mechanical properties inherent to the polyethylene resin even when a large amount of hydrated metal oxide is added, it is important to select a suitable polyethylene resin. In particular, as a covering material for electric wires and cables, for example, in the case of polyethylene electric wires, it is required to have an elongation at break of 350% or more, so in this case, ethylene with a vinyl acetate content of 10 to 75% by weight is used. - Vinyl acetate copolymer, ethylene-ethyl acrylate copolymer with ethyl acrylate content of 5-30% by weight, density 0.910-
0.945 (g/cm ³ ), melt index 0.01-2.0
(g/10 min) of polyethylene and ethylene-α-
It is necessary to use a polyethylene resin selected from the group consisting of olefin copolymers. Considering not only elongation properties but also heat resistance, surface hardness, etc., ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer is recommended.
Polyethylene with 90-25% by weight and the above properties
Mixtures with 10-75% by weight are most preferred. The organic phosphate compound used in the present invention is a compound obtained by reacting a nitrogen-containing organic compound with phosphoric acid, such as melamine phosphate, guanidine phosphate, phosphoric acid amide, guanylurea phosphate, etc. Of these, melamine phosphate and guanidine phosphate are preferred. The amount of organic phosphate compound added is 1 to 30 per 100 parts by weight of polyethylene resin.
parts by weight, preferably 3 to 10 parts by weight. Even if it is added in an amount larger than this upper limit, the effect of improving flame retardancy will not increase, and on the contrary, the tensile and pressing properties will deteriorate, which is not preferable. If the amount is less than the above-mentioned lower limit, the effect of addition will be insufficient, which is not preferable. The above-mentioned organic phosphate compounds have the effect of synergistically improving flame retardancy when used in combination with hydrated metal oxides in the above-mentioned proportions, and even when used in large amounts exceeding the above-mentioned proportions, flame retardancy does not improve. No improvement effect was observed. Since organophosphate compounds tend to deteriorate extrusion and mechanical properties and are also expensive, it is of great practical advantage that a relatively small amount can be sufficient as described above. The hydrated metal oxide used in the present invention is, for example,
Aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, calcium hydroxide, barium hydroxide, hydrotalside, dawsonite,
These include tin oxide hydrate, zirconium oxide hydrate, borax, hard clay, etc., or a mixture of two or more of these. Furthermore, these hydrated metal oxides include, for example, oxides such as alumina and titania; carbonates such as calcium carbonate; borates such as zinc borate; silicates such as talc; and sulfates such as gypsum. ; One type or two or more types of phosphates such as calcium phosphate can also be mixed. As the hydrated metal oxide, aluminum hydroxide, magnesium hydroxide, and basic magnesium carbonate are particularly preferred.
Among these, it is particularly preferable to use aluminum hydroxide and basic magnesium carbonate in combination because a synergistic effect is observed on the flame retardancy shown by the oxygen index. These inorganic substances are usually used in powder form, with an average particle size of 0.01 to 30μ, preferably 0.1 to 10μ.
It is. In addition, the amount of hydrated metal oxide added to the resin
80 to 250 parts by weight per 100 parts by weight, preferably
It is 100 to 200 parts by weight. If the amount of hydrated metal oxide added is smaller than the above lower limit, even if it is used in combination with organophosphate to take advantage of its synergistic effect, the UL-99
Does not reach the level of severe flame retardancy such as vertical combustion test. Moreover, if the amount is larger than the above-mentioned upper limit, the molding processability will be markedly deteriorated and mechanical properties such as tensile elongation at break will be markedly reduced, making it unsuitable for practical use. In the present invention, when it is desired to obtain a resin composition with particularly excellent elongation properties, it is recommended to add a surface treatment agent effective for improving the interfacial interaction between the polyethylene resin component and the hydrated metal oxide. preferable. Surface treatment agents effective for this purpose include titanate coupling agents, silane coupling agents, organic carboxylic acids and their salts, polyolefins modified with carboxylic acid compounds, and the like. Particularly preferred examples are isopropyl triisostearoyl titanate, isopropyl dimethacrylate
Monoalkoxy organic titanate compounds such as isostearoyl titanate and isopropyl isostearoyl diacrylic titanate; stearate salts such as stearic acid and zinc stearate; maleated polybutadiene, and the like. The amount of the surface treatment agent added is based on 100 parts by weight of the hydrated metal oxide.
It ranges from 0.1 to 10 parts by weight. As for the timing of addition, it may be added during kneading of the resin composition, or the hydrated metal oxide may be treated with a surface treatment agent in advance. In addition, various other additives commonly used in the resin composition of the present invention may be added, such as lubricants, antioxidants, ultraviolet absorbers, metal deterioration inhibitors, pigments, antistatic agents, thickeners, and foaming agents. A crosslinking agent, a crosslinking agent, a crosslinking aid, etc. can be contained. Further, the resin composition of the present invention can be crosslinked by irradiation with an electron beam or the like, and can also be made into a crosslinked product by chemical means such as silane crosslinking or peroxide crosslinking. The resin composition of the present invention can be generally produced by uniformly kneading the ingredients using a two-roll mill, Banbury mixer, kneader, etc., and then molding it using an extruder, injection molding machine, etc. Its uses span a wide range of fields, including coating materials for electric wires, cables, metal tubes, etc., various injection molded parts, and extrusion molded products in sheet form and irregularly shaped lengths. Next, the present invention will be explained with reference to examples. Example 1 This example illustrates the effect of adding an organic phosphate compound. Commercially available ethylene containing 25% vinyl acetate by weight
Vinyl acetate copolymer (manufactured by Mitsui Polychemical Co., Ltd., Evaflex 360) 50 parts by weight, density 0.922
g/cm ³ , melt index 0.7 g/10 min medium density polyethylene (Mitsui Petrochemical Co., Ltd., Neozetsuku 2006H), 50 parts by weight, aluminum hydroxide powder with an average particle size of 1.0 μm (Showa Denko Co., Ltd., Heidi) A mixture consisting of 150 parts by weight of Light H-42M) and 0 to 15 parts by weight of guanidine phosphate (manufactured by Sanwa Chemical Co., Ltd.) was heated to a temperature of 140°C using a small tabletop kneading device. The mixture was uniformly kneaded to obtain a resin composition. Next, each resin composition was molded to a thickness of 140°C using an electrically heated press molding machine.
It was formed into a 1/8 inch (3.175 mm) sheet. Samples taken from the sheets of each of the compositions thus obtained were tested for mechanical properties and flame retardancy based on the method specified in the UL-94 vertical combustion test. The composition of the tested materials and the test results are shown in Table 1. For comparison, similar tests were conducted on resin compositions obtained by adding no guanidine phosphate and varying the amount of aluminum hydroxide added in the range of 120 to 160 parts by weight. I went. The results are shown in Table 2. From the results shown in Table 1, aluminum hydroxide
The resin composition containing 150 parts by weight and no guanidine phosphate (Experiment No. 1) completely failed the V-0 criterion due to dripping (i.e., melt dripping); 2
Resin compositions containing at least parts by weight (Experiment No. 2~
5), it can be seen that there is no dripping and the V-0 standard is passed. On the other hand, the results shown in Table 2 show that even if only aluminum hydroxide is added in the range of 120 to 160 parts by weight, it does not pass the V-0 standard. Moreover, from Tables 1 and 2, it can be seen that flame retardancy is significantly improved by the combined addition of a very small amount of guanidine phosphate.

【table】

【table】

[Table] also means that the test does not pass.
Example 2 Commercially available ethylene containing 25% by weight of vinyl acetate
85 parts by weight of vinyl acetate copolymer (same as that used in Example 1), high-density polyethylene with a density of 0.935 g/cm ³ and a melt index of 0.2 g/10 min (manufactured by Showa Yuka Co., Ltd., Shorex)
4002E) 15 parts by weight, aluminum hydroxide powder (same as that used in Example 1) in a predetermined amount within the range of 150 to 160 parts by weight, melamine phosphate (manufactured by Sanwa Chemical Co., Ltd.) 0 to 10 parts by weight A resin composition having a predetermined amount within the range of 100% was prepared in the same manner as in Example 1, and the mechanical properties and UL-94 vertical combustion test were conducted on this resin composition in the same manner as in Example 1. In addition, in order to evaluate the tensile properties of the produced resin composition, a sheet with a thickness of 1 mm was manufactured, and JIS No. 3 dumbbell-shaped test pieces were punched out from this sheet.
C3005-1977 “Plastic insulated wire testing method”
A tensile test was conducted according to the method described in .
The results are shown in Table 3. From Table 3, it can be seen that by adding 2.5 parts by weight or more of melamine phosphate, the product passes the V-0 standard of the UL-94 test and maintains a high tensile elongation.

【table】

Claims (1)

[Claims] 1. 100 parts by weight of polyethylene resin, uniformly containing 80 to 250 parts by weight of hydrated metal oxide powder and 1 to 30 parts by weight of organic phosphate compound powder. Features a highly inorganic-filled flame-retardant resin composition. 2 The polyethylene resin contains 90 to 25% by weight of ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer and a density of 0.910 to 0.945 (g/
cm ³ ), melt index 0.01 to 2.0 (g/10 min)
A composition according to claim 1, comprising a mixture of 10 to 75% by weight of polyethylene.