JP5048936B2 - Flame-retardant molded article and flame-retardant resin composition - Google Patents

Description

  The present invention relates to a flame retardant molded article and a flame retardant resin composition. More specifically, the present invention relates to a flame retardant molded article formed by combining and blending specific flame retardants.

Synthetic resins such as polyolefin, polystyrene, polyamide, polyester, polyether, polycarbonate, phenol resin, and epoxy resin are used in various fields as molding materials. In the field where flame retardancy is required, flame retardancy is actively imparted by blending a halogen-based flame retardant represented by decabromodiphenyl oxide into a synthetic resin.
Recently, there is a concern that halogen-based flame retardant materials may generate toxic and harmful gases and black smoke during combustion and molding, so there is a gradual shift to non-halogen flame retardants with low toxicity and low emission. Yes.
It has been reported many times that a synthetic resin can be made flame retardant in a molded article having a thickness of 0.8 to 3.2 mm by blending a non-halogen flame retardant. However, thin molded articles having a thickness of 0.7 mm or less are difficult to be flame retardant and have not yet been technically established.

The use of the following non-halogen flame retardants and flame retardant aids has been proposed for flame retarding of synthetic resin molded articles having a thickness of 0.8 to 3.2 mm.
Patent Document 1 discloses that a molded product having a composition of polyolefin resin / piperazine pyrophosphate / melamine pyrophosphate / silicon oxide and having a thickness of 3.2 mm has sufficient flame resistance (extreme oxygen index and UL94: vertical combustion test). It has been reported that
In Patent Document 2, a molded product having a composition of polyolefin resin / piperazine pyrophosphate / melamine pyrophosphate and a thickness of 0.8 to 2.5 mm (UL94: vertical combustion test) and 3.2 mm (extreme oxygen index) is obtained. It is reported that sufficient flame retardancy can be obtained. Applications are electrical insulating parts, specifically dielectric films and sheets.

  In Patent Document 3, the composition of polyolefin resin / nitrogen-containing phosphorus flame retardant is one or more selected from oxides / sulfates, hydroxystannic acid metal salts, boric acid metal salts, fatty acid metal salts, and metal acetates. It has been reported that the flame retardancy is improved by the addition of. Specifically, sufficient flame retardancy is obtained with a molded product having a thickness of 1.6 mm (UL94: vertical combustion test) and a thickness of 3.2 mm (extreme oxygen index).

However, in any of the documents, there is no description of flame retardancy for a thin molded article having a thickness of 0.7 mm or less, and no application is mentioned. It is difficult to make a synthetic resin flame retardant with a halogen-free flame retardant in a thin molded article having a thickness of 0.7 mm or less, particularly 0.6 mm or less, and has not been technically established yet.
U.S. Pat. No. 4,599,375 JP-A-7-228710 JP-A-2005-42060

The present invention has been made in view of the above-described problems, and even when the thickness is 0.7 mm or less, a flame-retardant molded product having high flame retardancy, that is, a high ultimate oxygen index and Izod impact strength can be produced. Furthermore, it aims at providing the flame-retardant composition which does not foam at the time of kneading | mixing, and the flame-retardant molded object obtained from it.

The inventors of the present invention have intensively studied to solve the above-mentioned problems. As a result, even if a resin composition containing a specific phosphorus-based flame retardant in combination and zinc oxide (ZnO) is molded thinly, It has been found that extremely excellent flame retardancy can be exhibited.
In addition, the inventors have found that a resin composition containing a specific phosphorus-based flame retardant and a metal oxide in a resin mixture containing a polyolefin-based resin and a resin having a polar group can exhibit excellent flame retardancy, and completed the present invention. It was.

According to the present invention, the following flame retardant molded article and flame retardant resin composition are provided.
1. A flame retardant molded article comprising the following components (A) to (D) having a maximum thickness of 0.7 mm or less and an oxygen index of 24 or more.
(A) Polyolefin resin: 47-89.9 mass%
(B) Piperazine pyrophosphate and / or piperazine polyphosphate: 5 to 25% by mass
(C) At least one melamine compound selected from the group consisting of dimelamine pyrophosphate, melamine pyrophosphate and melamine polyphosphate: 5 to 25% by mass
(D) Zinc oxide (ZnO): 0.1 to 3% by mass
2. 2. The flame-retardant molded article according to 1, wherein the polyolefin-based resin of the component (A) has a melt index (MI: 230 ° C., load 2.16 kg) of 0.1 to 20 g / 10 min.
3. The flame retardant molded article according to 1 or 2, wherein the polyolefin resin of the component (A) is a mixture containing 50 to 99% by mass of a polypropylene resin and 1 to 50% by mass of a thermoplastic elastomer.
4). The flame retardant molded article according to 1 or 3, wherein the polyolefin resin of the component (A) is a mixture containing 70 to 99% by mass of a polypropylene resin and 1 to 30% by mass of a resin having a polar group.
5. The flame-retardant molded article according to any one of 1 to 4, wherein the component (B) is piperazine pyrophosphate and the component (C) is dimelamine pyrophosphate.
6). The flame-retardant molded article according to any one of 1 to 5, which is a corrugated tube having a maximum thickness of 0.6 mm or less.
7). A flame retardant resin composition comprising the following components (A) to (D).
(A) Resin mixture containing 70 to 99.5% by mass of a polyolefin-based resin and 0.5 to 30% by mass of a resin having a polar group: 47 to 89.9% by mass
(B) Piperazine pyrophosphate and / or piperazine polyphosphate: 5 to 25% by mass
(C) At least one melamine compound selected from the group consisting of dimelamine pyrophosphate, melamine pyrophosphate and melamine polyphosphate: 5 to 25% by mass
(D) Metal oxide: 0.1 to 3% by mass

From the flame retardant composition of the present invention, a flame retardant molded article having high flame retardancy and Izod impact strength can be produced even when the thickness is 0.7 mm or less, and the flame retardant composition of the present invention is kneaded. Sometimes does not foam .

Hereinafter, the flame-retardant molded article of the present invention will be specifically described.
The flame-retardant molded article of the present invention is obtained by granulating a resin composition containing the following components (A) to (D) using, for example, a kneader described later, so that the maximum thickness is 0.7 mm or less. It is obtained by molding as follows.
(A) Polyolefin resin: 47-89.9 mass%
(B) Piperazine pyrophosphate and / or piperazine polyphosphate: 5 to 25% by mass
(C) At least one melamine compound selected from the group consisting of dimelamine pyrophosphate, melamine pyrophosphate and melamine polyphosphate: 5 to 25% by mass
(D) Zinc oxide (ZnO): 0.1 to 3% by mass
The mass fraction means a value with respect to the total mass of the components (A) to (D).

Examples of the component (A) polyolefin-based resin include polypropylene-based resins, polyethylene-based resins, polybutene-based resins, polypentene-based resins, and thermoplastic elastomers.
Examples of the polypropylene resin include a propylene homopolymer (polypropylene) and a copolymer containing propylene as a main component. Examples of the copolymer include a propylene / α-olefin copolymer. Examples of the α-olefin include ethylene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-butene. , 1-pentene and the like.

  Examples of the polyethylene resin include an ethylene homopolymer (polyethylene) and a copolymer containing ethylene as a main component. Examples of the copolymer include an ethylene / α-olefin copolymer. Examples of the α-olefin include 1-hexene, 4-methyl-1-pentene, 1-octene, 1-butene, 1 -A pentene etc. are mentioned.

Thermoplastic elastomers include polyolefin-based thermoplastic elastomer (TPO), styrene-based thermoplastic elastomer [styrene-butadiene rubber (SBR), styrene-butadiene block copolymer (SBS), hydrogenated styrene / ethylene / butylene / styrene block. Copolymer elastomer (SEBS), styrene / isoprene / styrene block copolymer (SIS), styrene-isoprene rubber (SIR), styrene-ethylene-propylene-styrene block copolymer (SEPS), polystyrene-poly (ethylene / butylene) Block copolymers, polystyrene-poly (ethylene / propylene) block copolymers, styrene-ethylene / butylene-ethylene block copolymers, etc.] can be used.
In particular, a hydrogenated butadiene block copolymer, block TPO, or hydrogenated styrene-butadiene block copolymer is preferably used.

The brand names include, for example, Dynatron 6200 of JSR Corporation, R-110MP of Prime Polymer Co., Ltd., Clayton series such as Clayton G1651 of Shell Chemical Co., Ltd., Septon Series such as Septon 2104 of Kuraray Co., Ltd., Asahi Kasei The Tuftec H series of Co., Ltd. is listed.
The polyolefin resin used in the present invention may be one kind of the above-mentioned polyolefin resin or a mixture of two or more kinds.

In the present invention, the melt index (MI) of the polyolefin resin as the component (A) is preferably 0.1 to 20 g / 10 min (measured at 230 ° C. and a load of 2.16 kg). When MI is less than 0.1 g / 10 min, the flame retardant decomposes due to shear heat generation during production, which may result in poor molding and flame retardancy. In addition, white aggregates (flame retardant and zinc oxide poor dispersion) are observed, which may cause poor appearance. On the other hand, if MI exceeds 20 g / 10 min, the melt may sag during extrusion molding of the composition, and a good product may not be obtained.
More preferable MI is 2 to 10 g / 10 min.

In the present invention, it is preferable to use a mixture of a polypropylene resin (PP) and a thermoplastic elastomer as the polyolefin resin of the component (A) in order to impart flexibility to the molded body.
The mixing ratio is preferably 50 to 99% by mass for the polypropylene resin and 1 to 50% by mass for the thermoplastic elastomer. When PP is less than 50% by mass, that is, when the thermoplastic elastomer exceeds 50% by mass, the composition becomes too flexible and the mechanical properties required for the molded article may not be obtained. On the other hand, if PP exceeds 99% by mass and the thermoplastic elastomer is less than 1% by mass, the composition becomes too hard and the mechanical properties required for the molded article may not be obtained.
More preferable mixing ratio is 80 to 98% by mass for the polypropylene resin and 2 to 20% by mass for the thermoplastic elastomer.

In order to improve the flame retardancy, it is preferable to use a mixture of a polyolefin resin (preferably polypropylene) and a resin having a polar group as the polyolefin resin of the component (A).
Examples of the polar group of the resin having a polar group of the present invention include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an ester group, a carboxyl group, a carboxylic acid group, a carboxylic acid anhydride group, a carboxylic acid ester group, Carboxylic acid halide groups, carboxylic acid amide groups, carboxylic acid imide groups, carboxyl group derivatives such as carboxylic acid groups, sulfonic acid groups, sulfonic acid ester groups, sulfonic acid chloride groups, sulfonic acid amide groups, sulfonic acid groups, epoxy groups Amino group, oxazoline group, epoxy group and the like. Among these, a carboxylic acid group and a carboxylic anhydride group are preferable, and a functional group derived from an unsaturated carboxylic acid or a derivative thereof is particularly preferable.

  Specific examples of the resin having a polar group include, for example, ethylene vinyl acetate copolymer (EVA), ethylene ethyl acrylate copolymer (EEA), maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene, and phthalic acid-modified polypropylene. Alternatively, polyethylene, epoxy-modified polypropylene or polyethylene, compounds having the above-described polar group, and those obtained by modifying the above-described styrene-based thermoplastic elastomer or olefin-based thermoplastic elastomer can be used.

The mixing ratio is preferably 70 to 99.5% by mass for the polyolefin resin and 0.5 to 30% by mass for the resin having a polar group. If the ratio of the resin having a polar group exceeds 30% by mass, the resin becomes too flexible and the mechanical properties required for the molded article may not be obtained. On the other hand, if it is less than 0.5% by mass, sufficient flame retardancy may not be obtained.
A more preferable mixing ratio is that the mass of the polypropylene resin is 80 to 99 mass% and the mass of the resin having a polar group is 1 to 20 mass%.

  The blending amount of the component (A) in the total amount of the components (A) to (D) is 47 to 89.9% by mass in relation to the blending amount of the components (B) to (D) described later.

Regarding the piperazine pyrophosphate or piperazine polyphosphate that is the component (B), piperazine pyrophosphate can be synthesized according to a known method such as the method of JP-A-2005-120021. As the piperazine polyphosphate, for example, those disclosed in International Publication No. 2004/00973 can be used. You may use these individually by 1 type or in mixture of 2 types. Preferably, piperazine pyrophosphate is used.
Note that piperazine phosphate and dipiperazine pyrophosphate are difficult to use because they decompose and foam during kneading.
The blending amount of the component (B) in the total amount of the components (A) to (D) is 5 to 25% by mass, preferably 6 to 24% by mass, and particularly preferably 7 to 23% by mass. If it is less than 5% by mass, sufficient flame retardancy cannot be obtained. On the other hand, if it exceeds 25% by mass, the flame retardancy will be good, but the mechanical properties, impact properties, etc. will be reduced, and the cost will be further increased.

As component (C), at least one or more of dimelamine pyrophosphate, melamine pyrophosphate, and melamine polyphosphate are used. Preferably, dimelamine pyrophosphate is used.
These can use a commercial item. Note that melamine phosphate and dimelamine phosphate are difficult to use because they decompose and foam during kneading.
The blending amount of the component (C) in the total amount of the components (A) to (D) is 5 to 25% by mass, preferably 6 to 24% by mass, and particularly preferably 7 to 23% by mass. If it is less than 5% by mass, sufficient flame retardancy cannot be obtained. On the other hand, if it exceeds 25% by mass, the flame retardancy will be good, but the mechanical properties, impact properties, etc. will be reduced, and the cost will be further increased.

There is no restriction | limiting in particular about the zinc oxide (ZnO) of (D) component, A commercial item can be used. By adding zinc oxide, flame retardancy can be improved and foaming during kneading can be prevented, so it has excellent flame retardancy (for example, an oxygen index of 24 or more), good appearance, and a maximum thickness of 0.7 mm or less. A molded body is obtained.
When the component (A) is a mixture of a polyolefin resin and a resin having a polar group, a metal oxide can be used as the component (D). For example, zinc oxide, magnesium oxide, chromium oxide, manganese oxide, tin oxide, aluminum oxide, cobalt oxide, iron oxide, vanadium oxide, aluminum oxide, iron oxide, calcium oxide, titanium oxide, and the like can be used. Zinc oxide is preferable.
When using a metal oxide other than zinc oxide, for example, it is excellent in flame retardancy like magnesium oxide, but foaming occurs when melt kneaded together with the above components (B) and (C). Since there exists a possibility, especially manufacture of the molded object whose maximum thickness is 0.7 mm or less may become difficult. It is used if it is a molded product with a thick wall thickness, or a molded product for an application in which the appearance and the like do not matter so much.

  The blending amount of the component (D) in the total amount of the components (A) to (D) is 0.1 to 3% by mass, preferably 0.2 to 2.8% by mass, particularly preferably 0.3 to 2.5% by mass. If it is less than 0.1% by mass, sufficient flame retardancy may not be obtained. On the other hand, if it exceeds 3% by mass, sufficient flame retardancy can be obtained, but the kneaded product may foam during production, resulting in unstable discharge and resin pressure.

In addition to the above components, conventionally known additives and other blends can be added or blended as necessary within a range that does not impair the object of the present invention.
For example, phosphorus compounds, phenol compounds, sulfur compounds, etc. can be used as antioxidants. As the weathering agent, benzophenone, salicylate, benzotriazole, hindered amine, and the like can be used. As the antistatic agent, anionic, cationic, nonionic, amphoteric and the like can be used. As the lubricant, fatty acids, fatty acid amides, fatty acid metal salts, fatty acid esters, hydrocarbons and the like can be used. As a nucleating agent, a metal salt type, a sorbitol type, etc. can be used. As the filler, talc, calcium carbonate, barium sulfate, glass fiber, mica, wollastonite and the like can be used. In addition, a metal deactivator, a colorant, an antiblooming agent, a surface treatment agent, and the like can be used.

  A flame retardant resin composition in which the respective components are mixed is obtained by melt-kneading the above-described components (A) to (D) with various additives as necessary. Examples of the method of melt-kneading include a method of using a high-speed stirrer represented by a Henschel mixer, a single or biaxial continuous kneader, a roll mixer and the like alone or in combination.

  In the present invention, when a kneading extruder described below is used, (1) the dispersibility of the flame retardant is remarkably improved, so that a high amount of flame retardant is exhibited with a small amount of flame retardant, and mechanical properties are remarkably improved. (2) No surging occurs, no flame retardant is ejected from the open vent, productivity is improved, and (3) extrusion performance (discharge amount) of melt-kneading is improved.

As a kneading extruder used by this invention, the continuous kneading extruder shown in FIGS. 1-4 can be illustrated. This device has the advantage of being easy to clean.
FIG. 1 shows a plan cross section of the apparatus, FIG. 2 shows a raw material supply unit in FIG. 1, FIG. 3 is a cross-sectional view along AA in FIG. 1, and FIG. 4 is a cross-sectional view along BB in FIG. .
This apparatus includes a first shaft 3 housed in a metal casing 1 and a second shaft 4 shorter than the first shaft 3, and the blended components supplied from the hopper are mixed through a raw material supply unit. It is introduced into the section 12 (first kneading section), melted and kneaded in the mixing rotor section 12 and the mixing rotor section 13 (second kneading section), sent to the tip side, and discharged.

As shown in FIG. 1, the casing 1 is entirely formed in a cylindrical shape, and is divided into two parts at the right and left at the approximate center. Note that a connecting member 1b, which is a separate member, is inserted in the divided portion of the casing 1. 1a is a hinge.
In the casing 1, there are formed a cylindrical cylinder 21, an eyebrow cylinder 20 connecting two cylindrical cylinders, and two bearing cylinders 22 and 23 formed in the connecting member 1b. A first shaft 3 and a second shaft 4 each having a screw portion 2 (raw material supply portion) are arranged in parallel in the eyebrow cylinder 20. The first shaft 3 and the second shaft 4 are fitted into the casing 1 via screw bases 30 and 31. The base end portions of the first shaft 3 and the second shaft 4 are inserted into a gear box (not shown) installed outside the casing 1 and are rotatably supported by bearings.

  Further, since the delivery screw portion 4a at the tip of the second shaft 4 is held at a predetermined position by the molten resin interposed between this portion and the cylinder 22, the entire second shaft 4 is rotatably supported. The Similarly, since the delivery screw portion 5a at the intermediate portion of the first shaft 3 is held at a fixed position by the molten resin interposed between this portion and the cylinder 23, the entire first shaft 3 can be rotated freely. Supported. And the center part of the 1st axis | shaft 3 and the 2nd axis | shaft 4 opposes so that it may not contact mutually, and a pair of mixing rotor parts 12 and 13 are each provided in the middle. The mixing rotor parts 12 and 13 are composed of opposed first rotor parts 12a and 12b and second rotor parts 13a and 13b, and are formed at positions separated from each other as shown. A second screw 2a is formed between the first rotor portion 12a and the second rotor portion 13a, and a second screw 2b is formed between the first rotor portion 12b and the second rotor portion 13b. ing. An open vent (not shown) is provided above the middle of the second screws 2a and 2b (location indicated by reference numeral 41).

  The first shaft 3 has an extension shaft portion 5. The extension shaft portion 5 is rotatably mounted in a cylindrical cylinder 21, and a screw 5b is formed over the entire length. The base end side of the extension shaft portion 5 is held in the connecting member 1b, and a flow restricting screw having a small screw groove and a small gap with the casing 1 and having a fine pitch as a damming structure in this portion. 5a is formed. In the flow rate regulating screw 5a, the flow rate of the blended component passing therethrough is regulated to the minimum, and the blended component is sufficiently kneaded. With the above-described configuration, the casing 1 is formed with a biaxial screw portion 6 in which the first shaft 3 and the second shaft 4 are arranged in parallel, and a single screw portion 7 including an extended shaft portion 5 portion. A material supply port 8 shown in FIG. 2 that communicates with the biaxial screw portion 6 is formed in the vicinity of the base end portions (location indicated by reference numeral 8a) of the first shaft 3 and the second shaft 4 in the casing 1. Yes. To this material supply port 8, a blended component sent from a supply device (hopper) 42 having a stirring blade is sent through a coil feeder 43 and a shooter 44. The shooter 44 is coupled to the material supply port. It is preferable that the shooter 44 is in a state where the lid is opened as shown in FIG. 1 and a screw feeder 45 is inserted to forcibly feed the blended components.

  On the other hand, a discharge port 10 for the composition is provided on the distal end 9 side of the extension shaft 5 in the casing 1. Further, in the casing 1, a devolatilization port (not shown) is formed above the base end side of the extension shaft portion 5 (location indicated by reference numeral 32). A valve portion 11 is provided on the casing 1 on the base end side of the extension shaft portion 5. The valve unit 11 is configured as follows. First, a vacant chamber 14 is formed on the distal end side of the delivery screw 4a, and a small-diameter passage 16 is provided in a part of the vacant chamber 14 so that the vacant chamber 14 communicates with the cylinder 21. A cylindrical valve body 15 is inserted into the vacant chamber 14 from the outside, and the valve body 15 can be moved forward and backward in the direction of arrow H. And since the volume of the empty chamber 14 becomes small, so that the valve body 15 approaches the channel | path 16, the flow path of a mixing | blending component becomes narrow. The valve portion 11 communicates the biaxial screw portion 6 and the single screw portion 7 and adjusts the flow rate by bypassing the molten resin reaching the single screw portion 7. A delivery screw portion 4 a is formed at one end of the second shaft 4 so that most of the molten resin blocked by the flow rate regulating screw portion 5 a is collected and the resin is pumped into the casing 1 through the valve portion 11. It has become. The flow rate adjusting mechanism may have other configurations. For example, the first shaft 3 can be moved in the axial direction, and a valve body is formed by the first shaft 3 and an uneven portion formed on the casing inner surface around the first shaft 3. It is also possible to make a structure for adjusting the degree of opening and closing of the flow path.

  Next, the operation of the continuous kneading extruder will be described. The blended components introduced from the material supply port 8 are sent in the direction indicated by the arrow G by the screw portion 2 (raw material supply portion) of the first shaft 3 and the second shaft 4, and the first rotor portions 12a and 12b (first kneading portion). Part), the resin is semi-molten and the density of the resin material is increased. By increasing the density of the resin in this way, the resin conveying ability of the second screws 2a and 2b can be increased and the amount of extrusion can be increased. The rotation speed of the 1st axis | shaft 3 and the 2nd axis | shaft 4 at this time is about 10-1500 rpm. The resin material sent by the second screws 2a and 2b is completely melted and kneaded by the second rotor portions 13a and 13b (second kneading portions). The melted and kneaded resin is sent into the empty chamber 14 by the delivery screw portion 4a, and is sent into the casing 1 through the passage 16 while the flow rate is adjusted by the valve body 15. By adjusting the flow rate in this way, the kneading residence time of the compounding component and the filling degree of the compounding component in the biaxial kneading unit 6 can be adjusted, so that the degree of kneading can be freely set by operating the valve unit 11. For this reason, the opening and closing degree of the valve part 11 can be controlled according to the state of the resin, so that the compounding components can be always uniformly kneaded.

  In addition, since the first rotor portion 12 and the second rotor portion 13 which are two sets of rotor portions are provided, the melting and kneading actions of the resin are strengthened, and the amount of extrusion is greatly increased. Furthermore, the flow regulating screw portion 5a and the delivery screw portion 4a in the connecting member 1b are each independently supported, and a bearing action is generated by filling the resin between these and the cylinders 22 and 23. It is possible to prevent each screw from causing galling in the rotation range. Then, the composition melted and kneaded and adjusted as described above is sent to the single screw portion 7 and necessary devolatilization is performed from a devolatilization port (not shown) provided at a location indicated by reference numeral 32. Then, it is sequentially fed by the extension shaft portion 5 and extruded from the discharge port 10. In the present invention, it is preferable to premix the compounding components before kneading by the kneading extruder. The premixing can be performed using a Henschel mixer, a tumbler or the like.

In the present invention, the L / D (length / diameter) of the biaxial screw of the kneading extruder is 12 or more, and the screw diameter D (mm) and the length Lf (mm) of the raw material supply section are ( Lf / D) /D=0.12 to 0.33 mm ⁻¹ is preferable. Further, the L / D of the biaxial portion is preferably 20 or more, more preferably 25 or more. When L / D is 12 or more, the flame retardant is sufficiently dispersed, and the flame retardant can be filled into the composition with high concentration and good dispersibility.
The relationship between the screw diameter D (mm) and the length Lf (mm) of the raw material supply unit is preferably (Lf / D) /D=0.12 to 0.30 mm ⁻¹ (Lf / D) /D=0.12 to 0.29 mm ⁻¹ is more preferable. When (Lf / D) / D is 0.12 mm ⁻¹ or more, surging does not occur, the discharge amount is reduced, and the dispersibility of the flame retardant is not insufficient. Further, even if (Lf / D) / D exceeds 0.33 mm ⁻¹ , further effects are not obtained in the prevention of surging, a stable discharge amount and the dispersibility of the filler, and the equipment cost only increases. . Here, the length Lf of the raw material supply unit refers to the distance from the position immediately below the center of the shooter to the first kneading unit (first mixing rotor unit) as shown in FIG.

  In the kneading extruder used in the present invention, the L1 / D (length / screw diameter) of the first kneading section on the side close to the raw material supply section is usually 7 to 13, and preferably 9 to 13. When L1 / D is 7 or more, the dispersibility of the filler becomes good, and the filler becomes difficult to be ejected from the open vent. When L1 / D is 13 or less, the thermoplastic resin and rubber are not excessively kneaded, the thermoplastic resin and rubber are not deteriorated, and the equipment cost can be suppressed.

  On the other hand, L2 / D (length / screw diameter) of the 2nd kneading part following the 1st kneading part is 2-10 normally, and 3-5 are preferable. When L2 / D is 2 or more, the dispersion of the flame retardant is good, and even if L2 / D exceeds 10, no further kneading effect is obtained, and only the equipment cost increases. When the raw material to be kneaded contains air, a volatile component, an evaporated component, or the like, it is necessary to provide an open vent between the first kneading unit and the second kneading unit. This is because this kneading extruder has a great effect of increasing the discharge amount.

  The rotation speed of the screw can be 10 to 1500 rpm depending on the characteristics of the composition to be produced. For example, when producing a high fluid composition for injection use, the high fluid composition has a low viscosity, and it is necessary to obtain a shear stress. On the other hand, when producing a composition for extrusion, molecular cutting is likely to occur, and the viscosity is lowered. Therefore, it is preferable that the number of rotations of the screw is low. Moreover, it is preferable from the point of the kneading | mixing effect to give the rotation speed different from the same rotation speed to the screw of a biaxial part. Usually, the rotation speed ratio is about 1: 1.1. In the damming structure, the screw groove at the end of the biaxial portion is formed shallowly so that the gap with the casing (see FIG. 1) is made small and the pitch is fine. Is controlled to a minimum and kneading is sufficiently performed.

  The screw of the biaxial kneading part is preferably a non-meshing different direction type in consideration of the dispersion of the flame retardant and the discharge amount of the composition. The shape of the screw is preferably a rotor type. The screw structure of the screw is preferably a double thread as shown in FIG. Each of the screw and the rotor is a segment, and kneading can be adjusted by the position of the rotor, L / D, chip clearance, or the like as necessary. The biaxial kneading part preferably has a function of adjusting the amount of resin at the end so that the residence time of the blended components in the kneading part can be adjusted according to the required characteristics of the composition. As such a function, an orifice adjusting function can be exemplified. In addition, the biaxial kneading section and the single-shaft extrusion section do not necessarily have an integral structure, and may be of a tandem type as long as they are kneading extruders that satisfy the above requirements. Preferably there is.

  If the flame retardant resin composition is produced by the above kneading extruder, the dispersibility of the flame retardant does not decrease even under high discharge rate conditions, and as a result, there is no decrease in flame retardancy and physical properties decrease. Can be suppressed. In addition, even if the kneader size (screw diameter) and the blending composition are changed by the predetermined screw design, the flame retardant can be dispersed under the condition of a high discharge amount, and the flame retardancy and physical properties are improved. As a result, the blending amount of the flame retardant can be reduced, and the cost can be reduced. Furthermore, there is no ejection and surging of the flame retardant from the open vent, and the productivity is also good.

The flame-retardant molded article comprising the flame-retardant resin composition of the present invention is excellent even if it is a thin material having a thickness of 0.7 mm or less, particularly 0.6 mm or less, and further 0.2 to 0.4 mm. Has flame retardancy. Specifically, the oxygen index is 24 or more. When the oxygen index is less than 24, it becomes difficult to use in fields where flame retardancy is strongly required.
If the maximum thickness exceeds 0.7 mm, it is possible to obtain a molded article having an oxygen index of 24 or more without using the composition constituting the molded article of the present invention. The necessity to use is lost.

The flame-retardant molded article of the present invention can be suitably used for, for example, a corrugated tube used in an engine room of an automobile.
The flame-retardant resin composition can be processed into a thin molded article having a desired shape by a known molding method such as extrusion molding or injection molding. Alternatively, the components previously kneaded and granulated may be put into a molding machine and molded, or each component may be directly fed into the molding machine.

Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to these examples. In addition, the material used for the following reference example, an Example, and a comparative example is as follows.
・ Ingredient (A)
Polypropylene: “J-466HP (MI = 3.0 g / 10 min) and B-780 (powder)” manufactured by Prime Polymer Co., Ltd.
Thermoplastic elastomer: “Polyolefin-based thermoplastic elastomer (TPO), R110MP, MI = 2.0 g / 10 min” manufactured by Prime Polymer Co., Ltd.
Polar group-containing resin: “Ethylene Vinyl Acetate Copolymer (EVA), NUC3195, MI = 4 g / 10 min” manufactured by Nippon Unica Co., Ltd.
MI is a value measured at a temperature of 230 ° C. and a load of 2.16 kg in accordance with JIS K 7210. However, the polar group-containing resin is a value measured at a temperature of 190 ° C. and a load of 2.16 kg in accordance with ASTM D1238.

・ Ingredient (B)
Piperazine pyrophosphate It was prepared by reacting pyrophosphate and piperazine in a molar ratio of 1: 1.
Piperazine polyphosphate: prepared by reacting polyphosphoric acid and piperazine in a molar ratio of 1: 1 in an aqueous methanol solution.
・ Ingredient (C)
Melamine pyrophosphate: prepared by reacting pyrophosphate and melamine in a molar ratio of 1: 1.
Dimelamine pyrophosphate: “Melamine pyrophosphate (dimelamine pyrophosphate but trade name is melamine pyrophosphate)” manufactured by Shimonoseki Mitsui Chemicals, Inc.
Melamine polyphosphate: “Merapore 200” manufactured by Ciba Specialty Chemicals
・ Ingredient (D)
Zinc oxide: “Zinc oxide 1 type” manufactured by Sakai Chemical Industry Co., Ltd.
Others Magnesium oxide: “Kyowa Mag 3-150” manufactured by Kyowa Chemical Industry Co., Ltd.
Silicon oxide: “Toku Seal NP” manufactured by Tokuyama Corporation
Phosphorous antioxidant: “Adeka Stub 2112, Tris (2,4-di-t-butylphenyl) phosphite” manufactured by Asahi Denka Co., Ltd.
Phosphorus antioxidant: “AO-60, tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4-hydroxyphenyl) propionate] methane” manufactured by Asahi Denka Co., Ltd.

Reference Example 1 5 Example 1 4, Comparative Examples 1-3
(1) Premixing Each component was blended at the composition ratio shown in Table 1, and premixed with a Henschel mixer. In addition, 0.2 weight part of phosphorus antioxidant (ADK STAB 2112) and 0.1 weight part of AO-60 were added to 100 weight parts of the total amount of components (A) to (D).

(2) Melt-kneading The obtained preliminary mixture was kneaded with a CTM Co., Ltd., HTM type biaxial continuous kneading extruder “HTM38” (screw diameter: 38 mm, L / D = 28).
The HTM kneading and extruding machine has a biaxial kneading part and a uniaxial kneading part in an integral structure, the screw is of a non-meshing different direction type, and the screw structure of the screw is a double thread, and the biaxial kneading part The first kneading part and the second kneading part have a Mixing Groter, and the end of the biaxial kneading part has a damming structure and an orifice adjusting function for adjusting the resin flow rate. The discharge amount of the flame retardant resin composition was adjusted by the damming structure and the orifice adjusting function. The orifice opening was fully open.
The screw size of the kneader was as follows.
Screw diameter (D) = 38 mm, (Lf / D) /D=0.155, L1 / D = 12 of the first kneading part, L2 / D = 3 of the second kneading part
Moreover, kneading was performed under the operating conditions of a discharge rate of 70 kg / h, a cylinder set temperature of 180 to 200 ° C., and a screw rotation speed of 400 rpm.

(3) Physical property evaluation Flame retardant evaluation (oxygen index)
The composition pellet produced above was used as a test piece having a length of 120 mm, a width of 60 mm, and a thickness of 0.3 mm using a hot press. This test piece was evaluated as follows.
Tester: Toyo Seiki Seisakusho Co., Ltd., Candle Method Combustion Tester Model D-2 Type Test Method: Place the test piece in an atmosphere of various oxygen concentrations (volume%), bring the igniter close to the upper end, 4 seconds after ignition When the flame extinguishes within the range, or the flame does not reach, the igniter was moved close to 15 seconds, and then the maximum oxygen concentration (oxygen index) when extinguishing within 4 seconds was determined.

B. Evaluation of kneadability The case where foaming and vent-up during kneading were impossible to produce, or when foaming and voids were generated in the pellets was rated as x.
C. Izod impact strength (notched)
The composition pellets prepared above were injection molded at a cylinder temperature of 190 to 210 ° C. and a mold temperature of 50 ° C. using an injection molding machine (trade name FE-120) manufactured by Nissei Plastic Industry Co., Ltd. to produce a test piece. The Izod impact strength was measured in accordance with ASTM D256.
The results are shown in Tables 1 and 2.

Reference Example 1-4 has an oxygen index of 27 or more and no kneadability. In contrast, Comparative Example 1 uses magnesium oxide, which is a metal oxide other than zinc oxide, and has a high oxygen index, but foams during kneading and generates voids in the pellet. In Comparative Example 2, silicon oxide was used, but the oxygen index was as low as 22.
For example, the oxygen index pass value of a 0.3 mm thin corrugated tube is 23.5 or more. The oxygen index value of the film molded body close to the corrugated tube molded body of the resin composition of the reference example is 24 or more and passes.
Moreover, by adding EVA which is a polar group-containing resin as in Example 1-4 , the oxygen index is further increased and the Izod impact strength is also increased. Specifically, the Izod impact strength of the molded body of Reference Example 2 is 24 KJ / m ² , while the Izod impact strength of the molded body of Example 2 is 63 KJ / m ² .

  Even if the flame-retardant resin composition of the present invention is a thin molded product having a thickness of 0.7 mm or less, high flame retardancy (high ultimate oxygen index) can be obtained. Therefore, it can be suitably used for a corrugated tube molded body in an automobile engine room or the like.

It is sectional drawing seen from the top which shows an example of the kneading extruder used by this invention. It is sectional drawing seen from the side which shows the raw material supply in the kneading extruder shown in FIG. It is AA sectional drawing in FIG. It is BB sectional drawing in FIG.

Explanation of symbols

1 casing 2 screw part (raw material supply part)
3 First shaft 4 Second shaft 5 Extension shaft portion 6 Twin screw portion 7 Single shaft screw portion 8 Material supply port 9 End portion 10 Discharge port 12 Mixing rotor portion (first kneading portion)
13 Mixing rotor (second kneading part)

Claims (7)

A flame retardant resin composition comprising the following components (A) to (D).
(A) Resin mixture containing 70 to 99.5% by mass of a polyolefin-based resin and 0.5 to 30% by mass of a resin having a polar group: 47 to 89.9% by mass
(B) Piperazine pyrophosphate and / or piperazine polyphosphate: 5 to 25% by mass
(C) At least one melamine compound selected from the group consisting of dimelamine pyrophosphate, melamine pyrophosphate and melamine polyphosphate: 5 to 25% by mass
(D) Zinc oxide : 0.1 to 3% by mass   The flame retardant composition according to claim 1, wherein a melt index (MI: 230 ° C., load 2.16 kg) of the polyolefin-based resin of the component (A) is 0.1 to 20 g / 10 min.   The flame retardant composition according to claim 1 or 2, wherein the resin mixture of the component (A) is a mixture containing a thermoplastic elastomer.   The flame retardant composition according to any one of claims 1 to 3, wherein the component (B) is piperazine pyrophosphate and the component (C) is dimelamine pyrophosphate.   The flame-retardant molded object which consists of a flame-retardant composition in any one of Claims 1-4.   The flame-retardant molded article according to claim 5, having a maximum thickness of 0.7 mm or less and an oxygen index of 24 or more.   The flame-retardant molded article according to claim 5 or 6, which is a corrugated tube having a maximum thickness of 0.6 mm or less.

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