JP4964412B2 - Non-halogen flame retardant composition and electric wire - Google Patents

Description

  The present invention provides a non-halogen flame retardant composition having a good balance between heat resistance and withstand voltage characteristics, for example, suitable as an insulator for wiring in electrical equipment and automotive harnesses, and a coating comprising the non-halogen flame retardant composition It is related with the electric wire provided.

Olefin polymers such as polyethylene and ethylene-propylene rubber have been widely used as insulators for insulated wires since they are inexpensive and have good processability. However, since the olefin polymer itself is flammable, it is necessary to impart flame retardancy from the viewpoint of safety and fire resistance. As a method for imparting flame retardancy, for example, a method of adding a flame retardant is generally employed, but by adding an additive such as a flame retardant, mechanical strength and withstand voltage characteristics are greatly increased. It will be reduced. Therefore, for example, Patent Document 1 and Patent Document 2 disclose nonpolar olefin polymers having excellent voltage resistance characteristics such as polyethylene and ethylene-propylene rubber, and additives such as ethylene-vinyl acetate and ethylene-ethyl acrylate. A method for preventing deterioration of various properties due to the addition of an additive such as a flame retardant is disclosed by mixing a polar olefin polymer having an excellent affinity with a suitable ratio.

In recent years, the demand for materials that can be used in a high-temperature atmosphere has increased, and it has become a problem to impart high heat resistance to flame retardant compositions. Thus, for example, Patent Document 3 and Patent Document 4 disclose a method of adding hydrotalcites and additives such as antioxidants and metal deactivators to improve heat resistance by synergistic effects thereof. ing.

  As a technique related to the present case, Patent Document 5 has been filed by the applicant.

JP-A-8-180737 Japanese Patent No. 3092294 Japanese Patent Laid-Open No. 5-214175 Japanese Patent No. 3289424 Japanese Patent Application No. 2004-167433

However, as in Patent Document 1 and Patent Document 2 described above, the effect of improving the heat resistance cannot be obtained only by selecting a specific polymer, even if the mechanical strength and the withstand voltage characteristics can be prevented from being lowered. . In addition, although Patent Document 3 and Patent Document 4 have a description for improving heat resistance, there is no description on withstand voltage characteristics. In the first place, hydrotalcite is a crystal formed by ionic bond between an anion layer and a cation layer. In addition, since the crystal water is contained in the crystal, the withstand voltage characteristic is deteriorated, and when the additive as described above is added in a large amount in order to express high heat resistance, The withstand voltage characteristics are lowered due to problems in the properties and molecular structure. Furthermore, when hydrotalcites or the above-mentioned additives are added, the mechanical strength tends to be lowered. Thus, it has been difficult to obtain a flame retardant composition having both heat resistance and withstand voltage characteristics in a well-balanced manner with the conventional technology.

  In addition, as a flame retardant, a method of blending a halogen-based flame retardant has been widely adopted, but these generate a large amount of a halogen-based gas during combustion, corrosive to surrounding equipment, and harmful to the human body. In recent years, it has been demanded that no halogen-based material is contained.

  The present invention has been made to solve such problems of the prior art, and an object of the present invention is to provide a non-halogen flame retardant composition having a good balance between heat resistance and withstand voltage characteristics. is there.

In order to achieve the above object, a non-halogen flame retardant composition according to claim 1 of the present invention includes an olefin polymer, and a hydroxide 200 of a group 2 or 3 metal element with respect to 100 parts by weight of the olefin polymer. ~ 230 parts by weight, 2 to 50 parts by weight of an oxide of a group 2 or 3 metal element, 2 to 50 parts by weight of a hydrotalcite compound, and 2 to 30 parts by weight of an antioxidant. Then, the heat of crystal fusion of the flame retardant composition is 5 J / g or more and 50 J / g or less.
The halogen-free flame retardant composition according to claim 2 is characterized in that a phenolic antioxidant and a sulfur-based antioxidant are used in combination as the antioxidant.
In the non-halogen flame retardant composition according to claim 3, the metal element hydroxide of group 2 or 3 is at least one selected from magnesium hydroxide and aluminum hydroxide, and the group 2 or 3 The oxide of the group III metal element is zinc oxide.
According to a fourth aspect of the present invention, there is provided an electric wire provided with a coating made of the above flame retardant composition, wherein the flame retardant composition is crosslinked.

The flame retardant composition according to the present invention has excellent heat resistance by combining a specific amount of an oxide of a group 2 or 3 metal element and an inorganic substance having an ion exchange function in an olefin polymer. Can be obtained. Further, by adding a specific amount of a hydroxide of a group 2 or group 3 metal element, the withstand voltage characteristics are improved, and an oxide or ion exchange function of the group 2 or group 3 metal element, or Even if other additives and the like are added, it is possible to suppress a decrease in withstand voltage characteristics. Thus, according to the present invention, it is possible to obtain a flame retardant composition having a good balance between heat resistance and withstand voltage characteristics.
Moreover, since the softness | flexibility can be improved because the crystal melting heat amount of the said flame-retardant composition shall be 50 J / g or less, the flame-retardant composition suitable for the use for which flexibility is required is obtained. be able to.

  Hereinafter, each component which comprises the flame-retardant composition of this invention is demonstrated.

(A) Olefin polymer
Examples of the olefin polymer used in the present invention include polyethylene, ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl methacrylate copolymer, and ethylene-α olefin copolymer. Examples thereof include polymers and ethylene propylene rubber. Examples of the α olefin include 1-hexene, 1-butene, 4-methyl-1-pentene and the like. These may be used alone or in combination. Among these, it is preferable to contain a nonpolar olefin polymer such as polyethylene or ethylene propylene rubber. If such a non-polar olefin polymer is contained, it is possible to suppress a decrease in the withstand voltage characteristics due to the base polymer itself, so that the withstand voltage characteristics of the flame retardant composition can be improved.

(B) Group 2 or Group 3 Metal Element Hydroxides In the present invention, for the purpose of improving the withstand voltage characteristics by the action as an insulating filler and imparting flame retardancy, the group 2 or 3 A metal element hydroxide is added. Examples of the hydroxide of the group 2 or group 3 metal element include magnesium hydroxide, calcium hydroxide, barium hydroxide, and aluminum hydroxide. These may be used alone or in combination. Among these, magnesium hydroxide and aluminum hydroxide are preferable because they greatly contribute to the improvement of the flame retardancy of the flame retardant composition, and even when a large amount is blended, there is little decrease in heat resistance. Further, a hydroxide that acts as an acid acceptor, such as magnesium hydroxide or calcium hydroxide, is preferable because it improves heat resistance when an appropriate amount is blended. Further, as the hydroxide of the metal element of Group 2 or Group 3, it is preferable that the particle size is fine and the particle shape is uniform because the effect of improving the withstand voltage characteristic is high.

  The above-mentioned group 2 or group 3 metal element hydroxide is blended in an amount of 30 to 230 parts by weight per 100 parts by weight of the olefin polymer. When the blending amount of the hydroxide of the metal element of Group 2 or Group 3 is less than 30 parts by weight, the effect of improving the withstand voltage characteristic and the effect of imparting flame retardancy are insufficient as the insulating filler. If it exceeds the parts by weight, the mechanical strength and heat resistance will decrease. Moreover, if the compounding quantity of the hydroxide of a 2nd or 3rd group metal element is 200-230 weight part, the outstanding flame retardance can be provided.

(C) Group 2 or Group 3 Metal Element Oxide In the present invention, an oxide of a Group 2 or Group 3 metal element is blended for the purpose of improving heat resistance by the action as an acid acceptor. . Examples of Group 2 or Group 3 metal element oxides include magnesium oxide, calcium oxide, barium oxide, and zinc oxide. These may be used alone or in combination.

  The above-mentioned oxide of the group 2 or group 3 metal element is blended in an amount of 2 to 50 parts by weight with respect to 100 parts by weight of the olefin polymer. When the compounding amount of the oxide of the metal element of Group 2 or Group 3 is less than 2 parts by weight, the effect of improving heat resistance as an acid acceptor is insufficient, and when it exceeds 50 parts by weight, mechanical strength and The withstand voltage characteristic is degraded.

(D) In the inorganic olefin polymer having an ion exchange function, the catalyst used in the polymerization stage of the production process may remain as a residue. Such a catalyst residue produces a deterioration promoting component in an environment exposed to a high temperature, and thus adversely affects the heat resistance of the composition. In the present invention, an inorganic substance having an ion exchange function is blended for the purpose of capturing and inactivating the deterioration promoting component generated from the catalyst residue and improving the heat resistance. Examples of inorganic substances having an ion exchange function include hydrotalcite compounds, smectites, kaolins, and swellable mica. These may be used alone or in combination.

  The inorganic substance having the ion exchange function described above is blended in an amount of 2 to 50 parts by weight with respect to 100 parts by weight of the olefin polymer. When the blending amount of the inorganic substance having an ion exchange function is less than 2 parts by weight, it is insufficient for capturing and inactivating the deterioration promoting component, and sufficient heat resistance cannot be obtained. On the other hand, when the amount exceeds 50 parts by weight, the mechanical strength and withstand voltage characteristics are degraded.

  These Group 2 or Group 3 metal element hydroxides, Group 2 or Group 3 metal element oxides, and inorganic substances having an ion exchange function include, for example, higher fatty acids such as lauric acid, stearic acid, and oleic acid, Alternatively, the surface treatment can be performed with a surface treatment agent such as a higher fatty acid metal salt such as aluminum, magnesium or calcium salt, a silane coupling agent or a titanate surface treatment agent. These surface treatment agents are preferably used in order to improve the affinity and dispersibility with the olefin polymer and improve the mechanical strength and the like. Moreover, initial heat resistance can be improved by surface-treating with a silane coupling agent among the above-mentioned surface treatment agents. These surface treatment agents may be used alone or in combination of two or more. Moreover, when surface-treating, what was surface-treated beforehand may be used, and a surface treatment agent may be mix | blended with an untreated or surface-treated thing, and surface treatment may be performed.

  In the present invention, in addition to the above components, various additives that are conventionally used in electric wires and cables may be blended within a range that does not impair the object of the present invention. Examples of such additives include flame retardant aids, anti-aging agents, cross-linking agents, cross-linking aids, lubricants, softeners, dispersants, colorants, and the like.

Examples of the anti-aging agent include amine-based, phenol-based, phosphorus-based and sulfur-based anti-aging agents. These may be used alone or in combination. Among these, it is preferable to use a phenol-based anti-aging agent and a sulfur-based anti-aging agent in combination, and by providing a synergistic effect of a radical scavenging effect and a peroxide decomposition effect, a higher heat resistance is imparted, and bleed-out and coloring properties are improved. There is no pollution. Examples of the phenolic antioxidant include monophenols such as 2,6-di-t-butyl-4-methylphenol, 2,2′-methylene-bis- (4-methyl-6-t-butylphenol), and the like. Bisphenols such as 4,4′-thiobis- (6-t-butyl-3-methylphenol), thiobisphenols such as tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanate Examples include hindered phenols such as nurate, and sulfur-based anti-aging agents such as thioethers such as dilauryl thiodipropionate, imidazoles such as 2-mercaptobenzimidazole, nickel dibutyldithiocarbamate, etc. And thiocarbamate aging inhibitors. Of these, the combination of a hindered phenol anti-aging agent and an imidazole anti-aging agent is more preferable, and the highest effect of improving heat resistance is exhibited. Examples of the hindered phenol antioxidant include tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, 1,1,3-tris- (2-methyl-4-hydroxy). -5-t-butylphenyl) butane, tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, and the like. Examples of the imidazole anti-aging agent include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, 4,5-mercaptomethylbenzimidazole, and zinc salts thereof.

  These antioxidants are preferably blended in a total of 2 to 30 parts by weight with respect to 100 parts by weight of the olefin polymer. When the blending amount of the anti-aging agent is less than 2 parts by weight, the effect as an anti-aging agent is not sufficient, and when it exceeds 30 parts by weight, the withstand voltage characteristic is lowered.

  The flame retardancy of the present invention is obtained by adequately blending the above-described constituent materials with a known kneader such as a roll, kneader, Banbury, uniaxial kneader, or biaxial kneader. A composition can be obtained.

In the present invention, the heat of crystal fusion of the flame retardant composition thus obtained is preferably 50 J / g or less. If the amount of heat of crystal fusion of the flame retardant composition is 50 J / g or less, the flexibility can be improved, so that a flame retardant composition suitable for applications requiring flexibility can be obtained.

  An electric wire according to another embodiment of the present invention is formed by subjecting the above flame-retardant composition to extrusion coating on the conductor circumference by a known method, and then appropriately crosslinking to improve the heat resistance of the flame-retardant composition. Can be obtained.

  The crosslinking method is not particularly limited. For example, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-bis (t -Butylperoxy) -3,3,5-trimethylcyclohexane, chemical crosslinking method using an organic peroxide such as dicumyl peroxide as a crosslinking agent, X-ray, γ-ray, electron beam, proton beam, deuteron beam, Examples include an irradiation crosslinking method using ionizing radiation such as α rays and β rays. In addition, about the crystal heat of fusion mentioned above, when performing bridge | crosslinking, it is preferable that the crystal heat of fusion of the flame-retardant composition after bridge | crosslinking is 50 J / g or less.

  Examples of the present invention will be described below together with comparative examples. The details of each compounding material used in this example are as shown in Table 4.

The blended materials shown in Table 4 were sufficiently kneaded with a twin-screw kneader according to the number of blending parts shown in Tables 1 to 3, and the resulting flame retardant composition was pelletized. This pellet was supplied to a 25 mmφ extruder with L / D = 24, and tin-plated annealed copper stranded wire (0... 0) of American Wire Gauge (AWG) 28 under the temperature conditions of cylinder 70 to 100 ° C. and head 110 ° C. 4φ) was coated on the circumference of the conductor with a thickness of 0.35 mm. Then, it was chemically crosslinked under the conditions of 210 ° C. and 0.4 MPa to produce an electric wire having a finished outer diameter of 1.1 mmφ.

Here, using a total of 21 types of electric wires obtained in this way as samples, mechanical strength (tensile breaking strength, tensile breaking elongation), heat resistance, withstand voltage characteristics (dielectric breakdown voltage), flame retardancy, flexibility Each sex was evaluated. The results are shown in Tables 1 to 3 together with the number of blended parts of each blended material.

The evaluation method is as follows.
(Mechanical strength)
Based on UL758.14, the tensile strength at break and the tensile elongation at break were evaluated. As a pass / fail criterion, a sample having a tensile strength at break of 10.3 MPa or more and an elongation at break of 150% or more was determined to be acceptable.
(Heat-resistant)
With reference to the heat resistance test of UL758.14 (rated at 150 ° C), a 180 ° C short-term heat resistance test was performed. Put into a gear oven set at 180 ° C, take out after 7 days, measure the tensile elongation at break, pass the one that can maintain the residual strength after aging is 70% or more and the residual elongation at 50% or more The case where either (◯), the residual strength rate, or the residual tensile elongation at break was less than the value was regarded as rejected (x). In addition, referring to the heat resistance test (rated at 125 ° C.) of UL758.14, a long-term heat resistance test of 158 ° C. was performed. It put into the gear oven set to 158 degreeC with the electric wire which mix | blended the halogenated flame retardant, took out every 7 days, and measured tensile elongation at break. Measure the number of days that the tensile rupture strength after aging can hold 50% or more of the initial value and the elongation is 50% or more in absolute value, pass 35 days or more (○), and reject less than 35 days ( X).
(Withstand voltage characteristics)
The dielectric breakdown voltage in water was used for evaluation. The applied AC voltage was increased and the voltage at the time of dielectric breakdown was measured. Measurement was performed with the number of samples n = 10, and the average value was calculated. As a pass / fail criterion, a product having a dielectric breakdown voltage of 10 kV or higher was determined to be acceptable.
(Flame retardance)
Evaluation was performed using UL758.39 (horizontal combustion test) and UL758.41 (VW-1 combustion test).
(Flexibility)
As shown in FIG. 1 (A), the wire 1 having a length of 500 mm is used as a sample, the marked lines s and s ′ are drawn at a distance of 50 mm on the left and right from the center c, and the covering 1a is peeled off only 10 mm on both ends of the wire 1. The conductor 1b is exposed. Next, as shown in FIG. 1 (B), the ends of the conductors 1b are aligned and bundled, and suspended so that the center c of the electric wire 1 is placed on the mandrel 3 having a diameter of 2.0φ. A load of 0.98 N (100 g) is applied to the bound portion of the conductor 1b. Then, after applying the load, the distance L between the marked lines s and s ′ after one minute is measured. As a criterion for evaluation, it was determined that the distance L between the marked lines was less than 5 mm, especially soft, 5-10 mm soft, and 10 mm or more hard. Moreover, in the table | surface, the thing below 6 mm was shown as (double-circle), the thing of 6-11 mm was (circle), and the thing 11 mm or more was shown as (triangle | delta).

  In addition, the heat of crystal melting was measured for the above 21 types of samples. The measurement method was a differential scanning calorimetry (DSC) apparatus, where the temperature of the sample was raised from room temperature to 300 ° C., and the total endotherm was measured to obtain the heat of crystal fusion.

  In each of the above examples, each of the examples passed the horizontal combustion test, and it was confirmed that the flame retardant normally required.

  In addition, the electric wires according to this example all show acceptable values for heat resistance and withstand voltage characteristics, and have a good balance of heat resistance and withstand voltage characteristics, as well as mechanical strength (strength and elongation). It was also confirmed that it was excellent.

In particular, when Example 2 is compared with Examples 1, 12, and 13, Examples 1 and 12 containing an ethylene-propylene-diene copolymer or high-density polyethylene, which are non-polar olefin polymers, as the olefin polymer. , 13 were confirmed to be excellent in withstand voltage characteristics as compared with Example 2 which did not contain a non-polar olefin polymer.

  When Example 1, 3-7 is compared with the comparative example 1, the comparative example 1 by which the hydroxide of the metal element of 2 group or 3 groups is mix | blended exceeding the range (30-230 weight part) of this invention is the following. The mechanical strength and heat resistance are inferior to those of Examples 1 and 3-7, and both the mechanical strength test (strength and elongation) and the heat resistance test (180 ° C short-term heat test, 158 ° C long-term heat test) pass. It was confirmed that the level was not reached. Further, when Examples 1, 3 to 7 and Comparative Example 2 are compared, Comparative Example 2 in which a hydroxide of a metal element of Group 2 or Group 3 is not blended is more resistant than Examples 1, 3 to 7. It was confirmed that the voltage characteristics and flame retardancy were inferior, the value of the withstand voltage characteristic test did not reach the acceptable level, and the horizontal combustion test failed. In addition, Examples 4 and 5 in which the compounding amount of the hydroxide of the metal element of Group 2 or Group 3 is 200 to 230 parts by weight has passed the vertical flame test, and has particularly excellent flame retardancy. It was confirmed to have.

  When Examples 8 and 9 are compared with Comparative Example 3, Comparative Example 3 in which the oxide of the metal element of Group 2 or Group 3 exceeds the range of the present invention (2 to 50 parts by weight) It was confirmed that the withstand voltage characteristics were inferior to those of 8 and 9, and the value of the withstand voltage characteristics test did not reach the acceptable level. Further, when Examples 8 and 9 are compared with Comparative Example 4, Comparative Example 4 which does not contain an oxide of a metal element of Group 2 or Group 3 is inferior in heat resistance to Examples 8 and 9, and heat resistance It was also confirmed that the property test (158 ° C. long-term heat resistance test) did not reach the acceptable level.

  When Examples 10 and 11 are compared with Comparative Example 5, Comparative Example 5 in which the inorganic substance having an ion exchange function is blended exceeding the range (2 to 50 parts by weight) of the present invention is compared with Examples 10 and 11. Thus, it was confirmed that the withstand voltage characteristics were inferior and the withstand voltage characteristic test value did not reach the acceptable level. Further, when Examples 10 and 11 are compared with Comparative Example 6, Comparative Example 6 which does not contain an inorganic substance having an ion exchange function is inferior in heat resistance as compared with Examples 10 and 11, and a heat resistance test (158 ° C. It was also confirmed that the long-term heat test) did not reach the acceptable level.

  Moreover, when Examples 1, 2, 12 and Example 13 are compared, Examples 1, 2, 12 in which the heat of crystal fusion of the flame retardant composition is included in the preferred range of the present invention (50 J / g or less) Although it was soft and excellent in flexibility, Example 13 in which the heat of crystal fusion of the flame-retardant composition exceeded the preferable range of the present invention (50 J / g or less) was not problematic in practical use. However, it was slightly hard and poor in flexibility.

  In addition, when Examples 1, 14, and 15 are compared, since the blending amount of the antioxidant is within the preferred range (2 to 30 parts by weight) of the present invention, it is confirmed that all have excellent heat resistance. It was done.

As described above in detail, according to the present invention, it is possible to obtain a non-halogen flame retardant composition having a good balance between heat resistance and withstand voltage characteristics. Therefore, this flame retardant composition is suitable as an electrical device wiring or an insulator for an automobile harness. Further, the usage is not limited to these, and for example, it can be used as an insulating coating material for a cord-shaped heater, a constituent material for a tube, and the like.

It is the schematic showing the method of a flexibility test.

Explanation of symbols

1 electric wire 1a covering 1b conductor 2 weight 3 mandrel

Claims (4)

Olefin-based polymer, Group 2 or Group 3 metal element hydroxide 200 to 230 parts by weight, Group 2 or Group 3 metal element oxide 2 to 50 parts by weight with respect to 100 parts by weight of the olefin polymer A non-halogen flame retardant composition comprising 2 to 50 parts by weight of a hydrotalcite compound and 2 to 30 parts by weight of an anti-aging agent, wherein the heat of crystal fusion of the flame retardant composition is 5 J / g and 50 J / g or less, a non-halogen flame retardant composition. 2. The non-halogen flame retardant composition according to claim 1, wherein a phenol-based anti-aging agent and a sulfur-based anti-aging agent are used in combination as the anti-aging agent. The Group 2 or Group 3 metal element hydroxide is at least one selected from magnesium hydroxide and aluminum hydroxide, and the Group 2 or Group 3 metal element oxide is zinc oxide and magnesium oxide. The non-halogen flame retardant composition according to claim 1, wherein the non-halogen flame retardant composition is at least one selected from the group consisting of: An electric wire comprising a coating made of the flame retardant composition according to any one of claims 1 to 3 , and the flame retardant composition being cross-linked.

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