JPS625938B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a flame retardant for hydrocarbon thermoplastic polymer resins comprising a phosphoric acid ester having a styryl group and a brominated phenyl group. Hydrocarbon-based thermoplastic polymers, such as polyethylene, polypropylene, ethylene-propylene copolymer, polybutadiene, butadiene-styrene copolymer, polystyrene, polyisoprene, and other hydrocarbon-based polymers are easily flammable and are necessary for disaster prevention. When this is recognized, it is desirable to use these materials after undergoing flame retardant treatment. It is well known that various flame retardants and flame retardant methods have been proposed for this purpose. Examples of flame retardants include organic flame retardants such as chlorine or brominated paraffin, halogen-substituted aliphatic compounds such as chlorinated polyethylene, and halogen-substituted aromatic compounds such as hexabromobenzene and decabromodiphenyl ether. , triphenyl phosphate, tris(2,3 dibromopropyl) phosphate, and many other compounds such as aluminum hydroxide are known as inorganic flame retardants. Among them, halogen-substituted aromatic compounds such as bromine are known to be thermally stable and highly effective as flame retardants for hydrocarbon polymers. However, in the case of the so-called additive type flame retardant exemplified here, there is no chemical bond between the flame retardant and the polymer. For this reason, during long-term use, the flame retardant often oozes out onto the resin surface or evaporates at high temperatures, resulting in a decline in the flame retardant properties of the flame retardant resin molded product. Considering what happens when a flame retardant resin molded product actually encounters a fire, if the flame retardant has a small molecular weight and is additive, it will evaporate and evaporate from the molded product before the resin ignites due to flames or heat. This leads to a situation where the flame retardant effect is significantly reduced. For this reason, measures may be taken such as adding an excessive amount of flame retardant in advance, but adding a large amount of flame retardant can significantly impair mechanical properties such as strength and electrical properties such as insulation performance of flame retardant resin molded products. This causes a decrease in the amount of water. On the other hand, additive flame retardants with high molecular weights, such as chlorinated polyethylene, have been proposed.
In this case, there is little leaching from the resin or volatilization at high temperatures, which occurs with the low molecular weight ones mentioned above. However, these high molecular weight flame retardants are compatible only with resins having very similar molecular structures, and the compatibility between resins with different structures is very poor. Moreover, even if it appears to be mixed on the surface, it is often only dispersed non-uniformly, and the flame retardant effect is also poor. The present invention does not have the disadvantages of conventional flame retardants, that is, there is no leaching or volatilization of the flame retardant from the resin, and it exhibits good compatibility with a wide range of resins, and This paper attempts to present a new flame retardant method for hydrocarbon thermoplastic resins that can provide effective flame retardant effects even when used in small amounts. That is, in the course of conducting detailed basic research on flame retardant treatment of hydrocarbon thermoplastic polymers, which will be described later, the present inventors developed the general formula (In the formula, i is 1 or 2; j=3−i, and j
When = 1, n is 3, 4 or 5; when j = 2, n is an integer from 1 to 5, the sum of each n is 3 or more, and the vinyl group is ortho, meta or They discovered that a resin with excellent flame retardancy can be obtained by blending a polymerizable phosphoric acid ester represented by (present at the para position) and then polymerizing the ester. The polymerization-reactive styryl group in the phosphoric acid ester molecule according to the present invention provides heat resistance to this compound, and thus plays an important role in greatly improving the effectiveness of this compound as a flame retardant. For example, when this is changed to a group with poor thermal properties such as an acryloylethyl group (CH ₂ =CHCOOCH ₂ --CH ₂ --), the flame retardant effect on the polymer targeted by the present invention is extremely small. Furthermore, it is important that the bromine atom in this phosphoric acid ester molecule undergoes nuclear substitution with respect to the phenyl group. This is to improve the thermal decomposition temperature of the phosphoric ester. However, even in the case of nuclear bromination, for example, monobromophenyl compounds have a significantly small flame retardant effect. The flame retardant used in the present invention is characterized by its low molecular weight when mixed, so it exhibits good compatibility with many resins and is easily uniformly dispersed into the polymer. A feature of the present invention is that the polymerizable ester represented by the above general formula is polymerized in a thermoplastic polymer, whereby the phosphoric ester reacts with the thermoplastic polymer. Therefore, some phosphoric esters form a phosphoric ester graft polymer in a thermoplastic polymer, and some phosphoric esters form a homopolymer in the thermoplastic polymer. Therefore, the polymeric flame retardant is no longer leached out of the thermoplastic polymer. Furthermore, since the flame retardant is polymerized in the polymer, the flame retardant is uniformly dispersed, and a high flame retardant effect can be obtained. As will be described later, the phosphoric acid ester of the present invention exhibits the same flame retardant effect as, for example, about 1/2 the amount of bromine atoms as decabromodiphenyl ether, which is known as a brominated flame retardant. This also shows that the effect of the flame retardant in the present invention is extremely excellent. In addition, compared to 2,4,6-tribromophenyl acrylate, which is a polymerizable flame retardant and is already publicly known, the flame retardant of the present invention generates less smoke and toxic gas, and Leaves a large amount of hard residue. This is due to the phosphorus content, and the fact that the residue is hard and large is advantageous, for example, when used as a wire covering material, it allows electricity to be passed after a fire. Also,
Since the flame retardant of the present invention contains many aromatic rings in its molecule, it also has excellent radiation resistance. For this reason, it is ideal as an insulating material for electrical wires and cables for nuclear reactors. Thermoplastic polymers targeted by the present invention include ethylene, propylene, butene, isobutene,
It refers to a polymer whose main component is a monomer consisting of carbon and hydrogen, such as butadiene, isoprene, styrene, α-methylstyrene, or a mixture thereof. In addition, the polymers referred to in the present invention include various derivatives of the above monomers, acrylic acid and its esters, methacrylic acid and its esters, vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, vinyl chloride, vinylidene chloride, bromide. Copolymers with vinyl monomers such as vinyl, acrylonitrile, acrylic acid, and vinyl acetate, and mixtures of these with the above-mentioned hydrocarbon polymers also belong to the scope of the present invention. On the other hand, even if the flame retardant of the present invention is mixed with known additive flame retardants such as chlorinated paraffin, pentabromophenol, decabromodiphenyl ether, or other flame retardants, the effect may be reduced. Good flame retardant effect can be obtained. In particular, it is effective to use it in combination with polymerizable flame retardants containing double bonds in the molecule, such as 2,4,6-tribromophenyl acrylate and 2,4,6-tribromophenyl methacrylate. It is. The amount of flame retardant added to the polymer depends on the type of hydrocarbon polymer and the required degree of flame retardancy. Generally, the amount of flame retardant is 5 to 60 parts by weight per 100 parts by weight of the polymer. However, the flame retardant of the present invention is characterized by a large flame retardant effect, and does not require significantly excessive addition. Therefore, the amount is preferably 10 to 30 parts by weight. In addition, when the flame retardant of the present invention is used in combination with other known flame retardants, it is preferable to use an appropriate amount of antimony trioxide with respect to the amount of bromine in these flame retardants. In this case, the mixing ratio is generally 1 halogen atom
An appropriate amount of antimony atomic weight is 2 to 3 times the amount of antimony. To obtain the flame retardant resin according to the present invention, the polymer and flame retardant are first mixed together using various known methods. For example, a powdered or granular flame retardant may be added to a granular, powdered, flaky, or block polymer, mixed in a mixer, and kneaded using a hot roll, Brabender, or the like. Thereafter, polymerization is carried out after molding, and a radical generator is added just before molding, and polymerization is carried out by heating at the same time as molding. Alternatively, after molding, there is a method of polymerizing by irradiating with ionizing radiation or ultraviolet rays. It is not preferable to polymerize the phosphoric acid ester before molding, as this will cause crosslinking of the thermoplastic polymer, making subsequent molding difficult. In the flame retardant resin according to the invention, fillers, plasticizers, dyes, pigments, heat, light and radiation stabilizers, antioxidants,
It is also possible to incorporate ingredients such as antistatic agents, lubricants and similar substances. Examples will be presented below, in which oxygen index was adopted as a method of indicating flame retardancy. The method for measuring this value is standardized in JIS K7201 or ASTM D2863-70, and according to these, the oxygen index of polymeric materials is determined by the combustion time of the sample for 3 minutes or more, or by the combustion length. It is calculated from the minimum oxygen concentration required for the flame to continue burning for more than 50 mm. In the following examples, all parts and percentages are by weight unless otherwise specified. First, a synthesis example of bis(2,4,6-tribromophenyl)styryl phosphate, which is a typical phosphoric acid ester used in the present invention, will be shown. Synthesis Example Place 1 dehydrated benzene, 77g of phosphorus oxychloride, and 79g of pyridine in a flask, and prepare 331g of tribromophenol dissolved in 300cc of dehydrated benzene in a dropping funnel. A benzene solution of tribromophenol is added dropwise into the flask while stirring, and the mixture is allowed to react at a temperature of 30° C. for 8 hours. After the reaction is completed, pyridine hydrochloride is filtered off, benzene in the filtrate is distilled off under reduced pressure, and about 300 g of a disubstituted phosphorus oxychloride is obtained by recrystallization. This was dissolved again in 600 c.c. of dehydrated benzene and placed in a dropping funnel. Into the flask were placed 600 c.c. of dehydrated benzene, 49 g of paravinylphenol, and 41 g of triethylamine, and the mixture was added dropwise while stirring. React for 8 hours at a temperature of 30-35°C. After the reaction, triethylamine hydrochloride was filtered off, benzene in the filtrate was distilled off under reduced pressure, and bis(2,4,6-tribromophenyl) was obtained by recrystallization.
styryl phosphate Obtain 270g. Various compounds represented by formula (1) can be synthesized by similar methods. Examples 1 to 4 When ethylene propylene rubber is used as the polymer, for 100 g of ethylene propylene rubber,
Zinc white 5 parts, sulfur 0.5 parts, zinc stearate 1 part
part, anti-aging agent 1.5 parts, antimony trioxide 10 parts,
100 parts of talc, bis(2,4,6
-Tribromophenyl) styryl phosphate or bis(styryl), 30 parts of 2,4,6-tribromophenyl phosphate are mixed into ethylene propylene rubber on two rolls at 120°C, and then the roll The temperature was lowered to room temperature, and dicumyl peroxide (3 parts based on ethylene propylene rubber) was mixed as a radical generator. Further, this was compression molded into a sheet with a thickness of 3 mm at 100 kg/cm ² at 160° C. for 30 minutes. From this sheet, width 6.5mm,
A strip 150 mm long was cut out. The oxygen index of these samples is shown in Table 1. When polyethylene (low density) is used as the polymer, 0.5 parts of lead stearate, 0.5 parts of paraffin wax, 0.5 parts of anti-aging agent (Nokrac 300), and 10 parts of antimony trioxide are added to 100 g of polyethylene.
parts, 15 parts of dechlorane, as a flame retardant bis(2,4,6-tribromophenyl)styryl phosphate or bis(styryl), 2,4,6-
20 parts of tribromophenyl phosphate were mixed into the polyethylene on two rolls at 110°C, and then 3 parts of dicumyl peroxide was further mixed in as a radical generator. Furthermore, this was heated to 160℃ for 30
It was compression molded into a sheet with a thickness of 3 mm at 100 kg/cm ² for 1 minute. A strip with a width of 6.5 mm and a length of 150 mm was cut from this sheet. The oxygen index of these samples is shown in Table 1. Comparative Examples 1 and 2 Samples were prepared in the same manner as in the examples using known decabromodiphenyl ether as a flame retardant.
However, in order to make the bromine content equal to that in Example 1 or 3, the amount of flame retardant was 20 parts based on the ethylene propylene polymer and 14 parts based on the polyethylene polymer. Further, only antimony trioxide was adjusted to the same proportion as in Examples 1 to 4 according to the bromine content in the flame retardant. The oxygen index of these samples is shown in Table 2. Comparative Examples 3, 4 Bis(acryloylethyl) in which the styryl group of the phosphate ester flame retardant is converted into an acryloylethyl group, 2,4,6-tribromophenyl phosphate, and the tribromophenyl group is converted into a monobromophenyl group. A sample was prepared in the same manner as in the example using bis(4-bromophenyl) and styryl phosphate as a flame retardant. However, the amount of flame retardant was 30 parts based on the polymer. Table 3 shows the oxygen index of these samples. Examples 5 and 6 Bis(styryl), which is a flame retardant of the present invention,
2,4,6-tribromophenyl phosphate and 2,4, a known flame retardant containing a double bond.
6-Tribromophenyl acrylate was also used as a flame retardant. A sample was prepared in the same manner as in Example 2. However, in Example 5, the flame retardant was bis(styryl), 20 parts of 2,4,6-tribromophenyl phosphate, 10 parts of 2,4,6-tribromophenyl acrylate, and Example 6. Then, 10 parts of bis(styryl), 2,4,6-tribromophenyl phosphate, 2,4,6-
20 parts of tribromophenyl acrylate. Table 4 shows the oxygen index of these samples.

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[Table] Example 7 The same method as in Example 3 using ethylene-vinyl acetate copolymer as the polymer and bis(2,4,6-tribromophenyl) and styryl phosphate as the flame retardant. A sample was prepared. The oxygen index of this sample was 33. Comparative Example 5 A sample was prepared in the same manner as in Comparative Example 2 using ethylene-vinyl acetate copolymer as the polymer and decabromodiphenyl ether as the flame retardant. The oxygen index of this sample was 27.

Claims (1)

[Claims] 1. General formula (In the formula, i is 1 or 2, j = 3-i, and j
When = 1, n is 3, 4 or 5; when j = 2, n is an integer from 1 to 5, the sum of each n is 3 or more, and the vinyl group is ortho, meta or A flame retardant for hydrocarbon-based thermoplastic polymer resins consisting of a polymerizable phosphoric acid ester (present at the para position).