JPS62182B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a flame-retardant polyolefin molded article with excellent properties. Polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymers have excellent mechanical and electrical properties, and are therefore widely used in coating materials for electric wires and cables and in various electrical parts. In recent years, from the standpoint of disaster prevention, it has become necessary for the above-mentioned electric wires and cables to have highly flame-retardant coating materials, and there is a tendency for some to be required to do so. By the way, as mentioned above, polyolefin has the advantage of excellent mechanical and electrical properties, but on the other hand, it easily burns in the event of a fire, and it also poses serious problems in terms of disaster prevention, such as releasing a large amount of combustion heat and potentially spreading damage. It was hot. Therefore, various studies have been conducted regarding the development of flame retardant technology for polyolefins, and today, for example, (i) combination of halogen flame retardants, (ii) combination of halogen flame retardants and antimony trioxide, etc. (iii) Incorporation of powdered inorganic substances are well known. However, with method (i) above, a high degree of flame retardation cannot be obtained unless the amount of halogen flame retardant is considerably increased.
Furthermore, even if method (ii) allows the amount of halogen-based flame retardant to be reduced slightly, there is a limit to this, and in either case, black smoke is generated during combustion, and harmful halogen-containing gases are generated. I was worried that this would cause serious problems. The method in point (iii) has many advantages, such as eliminating the risk of generating such black smoke and harmful gases and helping to conserve waste resources. However, in order to obtain a high degree of flame retardancy, Significant increases in the amount, e.g. equivalent to or even more than the base polymer, may have to be incorporated in order to avoid the drawbacks that can significantly reduce the good mechanical properties of the polyolefin. Nakatsuta. As a result of intensive studies to solve this problem, the inventors of the present invention discovered that at least 80 parts by weight of a hydrated metal oxide is mixed with 100 parts by weight of polyolefin to make it flame retardant, as will be described in detail later. At least 0.5 parts by weight of a halogenated acenaphthylene polymer is blended with 100 parts by weight of polyolefin, and this composition is subjected to a free radical generation treatment to further polymerize the halogenated acenaphthylene polymer, or By blending at least 0.5 parts by weight of a halogenated acenaphthylene polymer, which is a condensation of at least two or more of the above-mentioned structural units, per 100 parts by weight of polyolefin, the above-mentioned problems can be significantly improved and excellent properties can be obtained. The present invention was completed based on the discovery that a flame-retardant polyolefin molded article with elasticity can be obtained. That is, this invention uses 80 to 250 parts by weight of hydrated metal oxide powder and the general formula 100 parts by weight of polyolefin. (However, X is any atom selected from hydrogen, chlorine, and bromine, Y is a chlorine or bromine atom, m is an integer of 2 to 6, R is a substituent other than a halogen atom,
n is an integer of 0 to 4; when n is 2 or more, R may be the same or different; one or more halogenated acenaphthylene multimers whose constituent elements are units represented by m+n≦6) A flame retardant method characterized by molding a desired molded article with a composition containing at least 0.5 parts by weight of the above substance per 100 parts by weight of polyolefin, and then subjecting the resulting molded article to a free radical generation treatment. This is a method for producing a polymer composition molded article. The reason why this invention solves the above problem is that although it has not necessarily been possible to do so clearly,
The mechanical properties of the composition are improved as a result of the excellent compatibility of the halogenated acenaphthylene polymer with the polyolefin and, after free radical generation treatment, also the increased affinity of the hydrated metal oxide for the polymer. This is thought to be due to the fact that it exhibits a preferable structure that significantly suppresses the decrease in . The polyolefin in this invention refers to a hydrocarbon polymer substance that is inherently flammable, such as polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, ethylene-propylene copolymer, etc. Examples include polymers, ethylene-propylene diene copolymers, and the like. The hydrated metal oxide that is mixed in to make this polyolefin flame retardant has the general formula Mm On XH ₂ O
(In the formula, M is a metal, m and n are integers of 1 or more determined by the valence of the metal, and X represents the number of bound water contained). Specific examples include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, zirconium oxide hydrate, tin oxide hydrate, basic magnesium carbonate, hydrotalcide usonite, borax, etc. One type or two or more types may be selected and used depending on the purpose of use.
In particular, aluminum hydroxide and magnesium hydroxide are particularly preferred from the viewpoint of their effectiveness and economy. The blending amount of these hydrated metal oxides is 80 to 250 parts by weight per 100 parts by weight of polyolefin, but below this lower limit, the original flame retardant effect cannot be expected, and above the upper limit, mechanical properties may deteriorate. Both are undesirable because they become too large and lack practicality. Next, the halogenated acenaphthylene multimer referred to in the present invention has the general formula It is indicated by. In terms of formation, halogenated acenaphthylene undergoes dehydrogenation or dehydrohalogenation reaction and condenses to form a multimer with a degree of condensation of 2 or more. Bonding points between acenaphthylene structural units include, for example, 1 (or 2), 5'-

[Formula] 1 (or 2), 6'-

[Formula] 4, 4′ (or is 4,7′,7,7′)

[Formula] 4,5' (or 4,6', 5,7)

[Formula] 5, 5' (or 5,6')

Examples include [Formula], but there are also 1, 1', 1, 2'-, 1
(or 2), 3'-, 1 (or 2), 4'-, 1 (or 2),
7′-, 1 (or 2), 8′-, 3,3′-, 3,4′-,
3,5'-, 3,6'-, 3,7'-, 3,8'-, 4,
Bonds such as 8'-, as well as, for example, 5,5' and 6,6',
It is also possible to condense via two bonds, such as 4,7' and 6,6'. Those having a degree of condensation of 3 or more are those in which the number of constituent units is increased by any of these bonds. Note that an upper limit of the degree of condensation of 10 or more is not preferable because the dispersibility in the composition will be significantly reduced and the effect of blending will be reduced. Such a multimer can be synthesized by first introducing a halogen at the allyl or benzyl position, and then taking advantage of its high reactivity and treating it in the presence of a catalyst, as described in the example below. . The compatibility between these halogenated acenaphthylene polymers and polymeric substances is good even without any substituents, but it can be further improved by introducing methyl groups, methoxy groups, methyl ester groups, etc. . This improves the processability during kneading and molding and the property of not volatilizing or exuding when the molded product is used for a long time at high temperatures. However, substituents with an excessively large number of carbon atoms are difficult to synthesize, and long-chain alkyl groups need to be avoided because they reduce flame retardancy and radiation resistance. Examples of substituents introduced for this purpose include alkyl groups having 1 to 4 carbon atoms, alkoxy groups, and alkyl ester groups. In order to exhibit the effects of the present invention, the blending amount must be at least 0.5 parts by weight per 100 parts by weight of the above-mentioned polymeric substance. Next, the composition as described above is molded into a suitable molded article, and the molding method may be extrusion molding, pressure molding or roll molding without particular limitation. The double bond between carbon 1 and carbon 2 of the halogenated acenaphthylene unit has radical polymerizability. Therefore, after mixing a multimer into a polymeric substance and forming a composition, it is further made into a multimer by subjecting it to a free radical generation treatment. In advance, dicumyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, di-t-butyl An appropriate amount of an organic peroxide such as peroxide, t-butyl hydroperoxide, di-isopropylbenzene hydroperoxide, or cumene hydroperoxide is mixed in and heated, or
There are methods such as irradiation with ionizing radiation such as rays, gamma rays, and electron beams. In the present invention, it is of course possible to add other reinforcing agents, extenders, crosslinking aids, pigments, lubricants, heat-light stabilizers, etc. to the above composition according to the purpose of use, as long as the properties do not deteriorate. do not have. According to the present invention, as is clear from the above description and the examples described later, in the method for producing a flame-retardant polyolefin molded product by incorporating a hydrated metal oxide, the deterioration of the mechanical properties of the resulting molded product is significantly suppressed. However, it is possible to solve the above-mentioned problems such as obtaining a highly flame-retardant molded article, and its industrial value is extremely high. The present invention will be specifically explained below with reference to Examples. Example of producing a multimer of halogenated acenaphthylene 1 A solution of 1 mol of 1,2,3,5-tetrabromoacenaphthene (C ₁₂ H ₆ Br ₄ ) in benzene (500 g), 2 mol of potassium bromide, and 0.2 mol of potassium bromate. An aqueous solution (600 g) of was placed in a three-necked flask and mixed with vigorous stirring in a dark place. Two moles of concentrated sulfuric acid was diluted with the same volume of water, and the mixture was added dropwise at around 10° C. under stirring, and reacted for 3 hours. After the reaction was completed, the benzene layer was washed with water, an aqueous solution of caustic soda (2%), and water again in this order, and dried with silica gel. Next, the dry benzene solution was transferred to a three-necked flask, and a warm ethanol solution in which about 2 moles of potassium hydroxide had been dissolved was added dropwise from a side pipe to carry out a dehydrobromation reaction. After the reaction was completed, the benzene layer was washed with water and dried. Furthermore, benzene was distilled off under reduced pressure, and the residue was thoroughly washed and dried with hot acetone to obtain a bromoacenaphthylene condensate. The compositional formula estimated from elemental analysis of the condensate was (C ₁₂ H _{3 .7} Br _{2 .9} )l. The degree of condensation l determined by GPC measurement was 2 to 5 as the main component. Example 2 A catalytic amount of stannic chloride was added to a chloroform solution of 1,2,3,5-tetrabromoacenaphthene and gently boiled and refluxed for about 3 hours. After the reaction was completed, the mixture was washed with water, dried, and chloroform was distilled off. Next, the residue was dissolved in benzene, and a dehydrobromination reaction was carried out in the same manner as in Example 1. The benzene layer was washed with water, dried, and then benzene was distilled off and thoroughly washed with hot acetone. The compositional formula of the obtained bromoacenaphthylene condensate is (C ₁₂ H ₄ . ₁ Br ₂ . ₃ )l
The main components had a degree of condensation l of 2 to 7 as determined by GPC measurement. Example 3 Dissolve 154 g of acetonaphthene in approximately 340 ml of carbon tetrachloride, maintain the temperature at 10°C, and dissolve 154 g of ferric chloride.
g was added. To this was added dropwise 960 g of bromine diluted with carbon tetrachloride while stirring well. After the dropwise addition was completed, the reaction system was heated to 45 to 55°C to complete the reaction. Next, the catalyst was filtered off, the solution was washed with water, and carbon tetrachloride was distilled off to obtain an intermediate bromoacenaphthene condensate. Next, in the same manner as in Example 1, the bromoacenaphthene condensate was subjected to a dehydrobromination reaction. The benzene layer was washed with water, dried, and then benzene was distilled off and thoroughly washed with hot acetone. The compositional formula of the obtained _{bromoacenaphthylene} condensate was ( _C12H1.7Br3.8 )l, and the degree of condensation l as _measured by GPC was 2 _{to 3} as the main component. Examples 1 to 3 and Comparative Examples 1 to 3 The compounds shown in Table 1, including polyethylene and aluminum hydroxide, were well kneaded with a heated roll, and this mixture was press-molded at 160°C for 30 minutes. Sheets with a thickness of 1 mm and 3 mm were obtained. The obtained sheet has mechanical properties and heat resistance according to JIS C 3005 (heating conditions: 150℃,
168 hours) and the oxygen index was measured according to JIS K 7201. The results are also shown in the same table. As is clear from the table, it is clear that the addition of the halogenated acenaphthylene polymer improves the mechanical properties and heat resistance of the composition, which are degraded by the addition of aluminum hydroxide, magnesium hydroxide, and the like.

[Table] Examples 4 to 7 and Comparative Examples 4 to 5 The blends shown in Table 2, including the ethylene-vinyl acetate copolymer and aluminum hydroxide, were thoroughly kneaded with a heating roll, and the resulting mixture The product was press-molded at 150° C. for 10 minutes to obtain sheets with a thickness of 1 mm and 3 mm. The obtained sheets were irradiated with an electron beam of 10 Mrad from one side of the 1 mm thick sheet, and 10 Mrad of electron beam from both sides of the 3 mm thick sheet using an electron beam accelerator. The mechanical properties, heat resistance, and oxygen index of the obtained sample were measured in the same manner as in Example 1, and the results are shown in Table 2. As is clear from the table, it is clear that the mechanical properties, heat resistance, and flame retardance of the composition are significantly improved by incorporating the halogenated acenaphthylene polymer.

[Table] As is clear from the above examples, flame-retardant polyolefin molded articles having excellent properties can be produced according to the method of the present invention, and its industrial value is extremely large.

Claims (1)

[Claims] 1. 80 to 250 parts by weight of hydrated metal oxide powder and the general formula, based on 100 parts by weight of polyolefin. (However, in the formula, X is any atom selected from the group of hydrogen, chlorine, and bromine, Y is a chlorine or bromine atom, m is an integer from 2 to 6, R is a substituent other than a halogen atom, and n is 0 An integer of ~4, if n is 2 or more, R
may be the same or different, m+n≦
After blending at least 0.5 parts by weight of a halogenated acenaphthylene polymer containing the unit represented by 6) as a constituent element and molding this composition into a desired molded product, free radicals are generated in the resulting molded product. A method for producing a flame-retardant polyolefin molded article, which comprises subjecting it to a treatment.