JP4642423B2 - Flame retardant polypropylene resin composition - Google Patents

Description

  The present invention relates to a flame retardant polypropylene resin composition. Specifically, the present invention relates to a polypropylene resin composition that satisfies both flame retardancy performance and heat aging prevention performance.

  Polypropylene resin is a material with excellent heat resistance and mechanical properties, and is a relatively stable resin. However, it gradually decomposes when exposed to heat, light, and air during the molding process and use process, and has physical properties. There is a drawback of lowering. Usually, a prescription is taken in which various stabilizers are added to prevent the embrittlement or deterioration (aging) and maintain the initial properties. Since the essential cause of such embrittlement or deterioration is due to the oxidation of the polypropylene resin, it is usually essential to add an antioxidant. For example, phosphorus antioxidants such as tris (2,4-ditertiarybutylphenyl) phosphite, 2,6-ditertiarybutyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- Tert-butyl-4-hydroxyphenyl) propionate] and the like.

  On the other hand, a flame retardant polypropylene resin composition obtained by mixing a polypropylene resin with a flame retardant and an antimony compound is widely known. For example, a method is known in which polypropylene resin pellets and paraffinic oil are mixed first, then a flame retardant and an antimony compound are blended and mixed, and melt kneaded (see Patent Document 1). The present invention is characterized in that the first-stage mixing step and the second-stage melt-kneading step are distinguished, and in the first-stage mixing step, the wet action of paraffin oil is skillfully used, The present invention provides a flame retardant polypropylene resin composition that improves the uneven distribution (distribution of distribution) of the flame retardant, improves the flame retardant performance, and has an excellent appearance without stickiness. However, according to the invention of Patent Document 1, the uneven accumulation is small and the flame retardancy is improved, but the heat aging resistance is not sufficiently satisfactory. Heat aging resistance can be improved to some extent by increasing the amount of antioxidants, heat stabilizers, etc., but increasing too much is economically disadvantageous and may degrade the basic physical properties of polypropylene resin. Is not preferable.

As a result of further improvements based on the invention of Patent Document 1, the present inventors have learned that the insufficient heat aging resistance is caused by a slight uneven accumulation of the organic flame retardant, By controlling the maximum particle size by pulverizing the organic flame retardant in advance, the above problems were solved and the present invention was completed.
JP 2004-168955 A

  The present invention further improves the uneven distribution (distribution of distribution) of the flame retardant in the polypropylene resin composition, improves the flame retardant performance and heat aging resistance, and has an excellent appearance without stickiness and the like. A composition is provided.

  That is, the gist of the present invention is that 9 to 22 parts by weight of an organic flame retardant having a maximum particle size of 100 μm or less and 5 to 15 parts by weight of an antimony compound are blended with 100 parts by weight of polypropylene resin pellets, and then the blend is melted. It exists in the flame-retardant polypropylene resin composition formed by kneading.

  ADVANTAGE OF THE INVENTION According to this invention, the uneven distribution (distribution of distribution) of the flame retardant in a polypropylene resin composition can be improved further, and a flame retardance performance and heat aging resistance can be improved. The excellent mechanical properties of the polypropylene resin can be expressed without increasing the blending amount of antioxidants, heat stabilizers, and the like. Therefore, it can be suitably used for home appliance parts, housing equipment parts, automobile parts, and the like.

1. Components of Polypropylene Resin Composition (1) Polypropylene Resin The polypropylene resin used in the present invention is a propylene homopolymer or a copolymer of propylene and an α-olefin other than propylene having 2 to 10 carbon atoms, such as propylene. It is a resin selected from an α-olefin random copolymer, a propylene / α-olefin block copolymer, and the like. The α-olefin used in the copolymer is, for example, selected from ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, and the like. Among them, ethylene, 1-butene, 1-octene Hexene is preferred, and ethylene is particularly preferred.

  When the polypropylene resin is a random copolymer of propylene and an α-olefin, the α-olefin content in the copolymer is preferably 0.1 to 20% by weight, more preferably 0.5 to 12% by weight, More preferably, it is 1 to 8% by weight. When the α-olefin content exceeds 20% by weight, it is not preferable because cotton ignition is easily caused by the influence of dripping during the UL94 combustion test and the flame retardancy level is lowered.

  When the polypropylene resin is a propylene / α-olefin block copolymer, the α-olefin content in the propylene / α-olefin copolymer portion is preferably 70% by weight or less, more preferably 30 to 60% by weight. When the α-olefin content is 70% by weight or more, it is not preferable because cotton ignition tends to occur due to the influence of dripping during the UL94 combustion test and the flame retardancy level decreases.

  The melt flow rate (MFR) of the polypropylene resin is preferably 5 to 100 g / 10 minutes, more preferably 10 to 80 g / 10 minutes, and further preferably 20 to 60 g / 10 minutes. If the MFR is less than 5 g / 10 min, cotton ignition tends to occur due to the influence of dripping during the UL94 combustion test, and the flame retardancy level tends to decrease, such being undesirable. On the other hand, if the MFR exceeds 100 g / 10 min, the moldability is deteriorated, which is not preferable. In addition, MFR is a value calculated | required based on JISK7210 (230 degreeC, 21.18N load) here.

  In the present invention, the polypropylene resin is used in the form of pellets. The shape of the pellet is not particularly limited, and examples thereof include a columnar shape, a prismatic shape, a spherical shape, and a flat plate shape. As the size of the pellet, those having a minor axis of 1 to 3 mm and a major axis of 3 to 10 mm are usually used. Powdered and fibrous materials are complicated in handling and are not used in the present invention.

(2) Organic flame retardant As the organic flame retardant used in the present invention, (a) an organic halogen flame retardant, (b) an organic phosphorus flame retardant, (c) an organic nitrogen flame retardant, and the like are used.

(A) Examples of organic halogen flame retardants include organic halogenated aromatic compounds such as halogenated diphenyl compounds, halogenated bisphenol compounds, halogenated bisphenol bis (alkyl ether) compounds, and halogenated phthalimide compounds. A flame retardant is preferable, and a halogenated bisphenol bis (alkyl ether) compound is particularly preferable.

  Examples of the halogenated diphenyl compound include a halogenated diphenyl ether compound, a halogenated diphenyl ketone compound, and a halogenated diphenyl alkane compound. Among them, a halogenated diphenyl ether compound such as decabromodiphenyl ether is preferable.

  Examples of the halogenated bisphenol compounds include halogenated bisphenyl alkanes, halogenated bisphenyl ethers, halogenated bisphenyl thioethers, halogenated bisphenyl sulfones, etc. Among them, bis (3,5 Halogenated bisphenyl thioethers such as -dibromo-4-hydroxyphenyl) sulfone are preferred.

  Examples of the halogenated bisphenol bis (alkyl ether) compound include (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl)-(3-bromo-4- (2,3-dibromo) propoxy. Phenyl) methane, 1- (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl) -2- (3-bromo-4- (2,3-dibromo) propoxyphenyl) ethane, 1- ( 3,5-dibromo-4- (2,3-dibromo) propoxyphenyl) -3- (3-bromo-4- (2,3-dibromo) propoxyphenyl) propane, 2,2-bis (3,5- Dibromo-4- (2,3-dibromo) propoxyphenyl) propane, (3,5-dichloro-4- (2,3-dibromo) propoxyphenyl)-(3-chloro-4- (2,3 Dibromo) propoxyphenyl) methane, 1- (3,5-dichloro-4- (2,3-dibromo) propoxyphenyl) -2- (3-chloro-4- (2,3-dibromo) propoxyphenyl) ethane, 1- (3,5-dichloro-4- (2,3-dibromo) propoxyphenyl) -3- (3-chloro-4- (2,3-dibromo) propoxyphenyl) propane, bis (3,5-dibromo -4- (2,3-dibromo) propoxyphenyl) methane, 1,2-bis (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl) ethane, 1,3-bis (3,5 -Dibromo-4- (2,3-dibromo) propoxyphenyl) propane, bis (3,5-dichloro-4- (2,3-dibromo) propoxyphenyl) methane, 1,2-bis (3,5- Chloro-4- (2,3-dibromo) propoxyphenyl) ethane, 1,3-bis (3,5-dichloro-4- (2,3-dibromo) propoxyphenyl) propane, 2-bis (3,5- Dichloro-4- (2,3-dibromo) propoxyphenyl) propane, (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl)-(3-bromo-4- (2,3-dibromo) Propoxyphenyl) ketone, (3,5-dichloro-4- (2,3-dibromo) propoxyphenyl)-(3-chloro-4- (2,3-dibromo) propoxyphenyl) ketone, bis (3,5- Dibromo-4- (2,3-dibromo) propoxyphenyl) ketone, bis (3,5-dichloro-4- (2,3-dibromo) propoxyphenyl) ketone, (3,5-dibromo-4 -(2,3-dibromo) propoxyphenyl)-(3-bromo-4- (2,3-dibromo) propoxyphenyl) ether, (3,5-dichloro-4- (2,3-dibromo) propoxyphenyl) -(3-chloro-4- (2,3-dibromo) propoxyphenyl) ether, bis (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl) ether, bis (3,5-dichloro- 4- (2,3-dibromo) propoxyphenyl) ether, (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl)-(3-bromo-4- (2,3-dibromo) propoxyphenyl ) Thioether, (3,5-dichloro-4- (2,3-dibromo) propoxyphenyl)-(3-chloro-4- (2,3-dibromo) propoxyphenyl) thio Ether, bis (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl) thioether, bis (3,5-dichloro-4- (2,3-dibromo) propoxyphenyl) thioether, (3,5 -Dibromo-4- (2,3-dibromo) propoxyphenyl)-(3-bromo-4- (2,3-dibromo) propoxyphenyl) sulfone, (3,5-dichloro-4- (2,3-dibromo) ) Propoxyphenyl)-(3-chloro-4- (2,3-dibromo) propoxyphenyl) sulfone, bis (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl) sulfone, bis (3 5-dichloro-4- (2,3-dibromo) propoxyphenyl) sulfone, among which brominated bisphenol A (brominated aliphatic amines). ), Brominated bisphenol S (brominated aliphatic ether), chlorinated bisphenol A (chlorinated aliphatic ether), chlorinated bisphenol S (chlorinated aliphatic ether), especially etherified tetrabromobisphenol A, etherified tetra Bromobisphenol S is preferred.

  As etherified tetrabromobisphenol A, tetrabromobisphenol A-bis ((2,3-dibromo) propyl ether), 2,2-bis (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl) Propane is exemplified. Examples of etherified tetrabromobisphenol S include bis (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl) sulfone.

(B) Examples of organophosphorus flame retardants include tricresyl phosphate, tri (β-chloroethyl) phosphate, tri (dibromopropyl) phosphate, 2,3-dibromopropyl-2,3-chloropropyl phosphate, and the like. And phosphoric acid esters, halogenated phosphoric acid esters, phosphonic acid compounds, phosphinic acid derivatives, and the like.

(C) Organic nitrogen flame retardants include guanidine compounds such as guanidine nitride, triazine compounds such as melamine, melamine oligomers, cyanuric acid, and cyanuric acid melamine.

  These (a) organic halogen flame retardant, (b) organic phosphorus flame retardant, and (c) organic nitrogen flame retardant may be used alone or in combination of two or more.

  The organic flame retardant used in the present invention has a maximum particle size of 100 μm or less, preferably 70 μm or less, more preferably 40 μm or less. When the maximum particle size is larger than this value, there is a disadvantage that the flame retardant is unevenly accumulated in the resin during kneading. As a result, the heat aging resistance is lowered, which is not preferable. On the other hand, the minimum particle size of the organic flame retardant is 0.5 μm or more, preferably 1 μm or more. If the value is below this value, it becomes super fine powder, causing difficulties in handling, which is not preferable in terms of work. Accordingly, the particle size range is usually 0.5 to 100 μm, preferably 1 to 70 μm. In addition, the particle size distribution has a logarithmic particle diameter on the horizontal axis and a semi-logarithmic graph of the abundance corresponding to the particle diameter on the vertical axis, with a bell-shaped distribution in the average particle size range of 5 to 20 μm. It is particularly preferable.

  The particle size distribution in the present invention is based on the laser diffraction particle size distribution measuring method. A measuring apparatus is not limited, A normal commercial item can be used. For example, a laser diffraction (scattering type) particle size distribution measuring apparatus manufactured by HORIBA, Ltd. can be used.

  Commercial products of organic flame retardants usually do not have the above-mentioned particle size characteristics, so they cannot be used as they are, and need to be pretreated before applying to the present invention. When the maximum particle size, particle size distribution, etc. do not satisfy the provisions of the present invention, the desired particle size distribution is adjusted by pulverizing a large particle size powder, removing fine powder, or dissolving in a solvent and then crystallizing. Is possible. Examples of the pulverization method include a method of pulverizing with a ball mill, jet mill, colloid mill or the like at a temperature lower than the melting point of the flame retardant.

(3) Antimony compound In the present invention, the antimony compound is used to increase the flame retardant effect by being blended with a polypropylene resin together with an organic flame retardant. Specific examples of the antimony compound include antimony halides such as antimony trioxide, antimony pentoxide, antimony trichloride, and antimony pentachloride, antimony trisulfide, antimony pentasulfide, sodium antimonate, antimony tartrate, and metal antimony. Representative examples. Since all the commercial products of antimony compounds are fine particles, they can be used in the present invention as they are.

(4) Other compounding components In the flame-retardant polypropylene resin composition of the present invention, although not an essential component, the following additives can be appropriately compounded according to the purpose and application. The components (b) to (e) shown below may already be contained in the polypropylene resin pellets, but may be further blended as necessary.

(A) Paraffinic oil The paraffinic oil used in the present invention is a hydrocarbon-based oil having a paraffin chain carbon number of 50% by weight or more in the total carbon, and having a weight average molecular weight of 300 to 2000. Those are preferred. The kinematic viscosity is 30 to 450 mm ² / S, preferably 30 to 150 mm ² / S. If the kinematic viscosity is less than 30 mm ² / S, the uneven distribution of the flame retardant in the polypropylene resin and the flame retardant mixture increases, which is not preferable. On the other hand, if it exceeds 450 mm ² / S, the uneven distribution increases. . Here, the kinematic viscosity of the paraffinic oil is a value measured at a temperature of 40 ° C. according to JIS-Z-8803. Specific examples of the paraffinic oil having the above physical properties include commercially available products such as “Diana Process Oil” manufactured by Idemitsu Kosan Co., Ltd. and “Purelex” manufactured by Esso.

(B) Antioxidants For example, pentaerythryl-tetrakis [3- (3,5-di-t-butyl-4-hydroxylphenyl) propionate], octadecyl-3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4- Hydroxylphenyl) propionate] and the like, tris (2,4-di-t-butylphenyl) phosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, tetrakis ( 2,4-di-t-butylphenyl) -4,4′-biphenylenediphosphonite and other phosphorus-based antioxidants It is below.

(C) Ultraviolet absorbers For example, dimyristyl-3,3′-thiodipropionate, distearyl thiodipropionate, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzo Triazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-n-octyloxybenzophenone, bis (2,2,6,6-tetramethyl-4- Piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and the like.

(D) Nucleating agent Examples include sorbitol compounds and fine silica.
(E) Antistatic agent For example, glyceryl monostearate etc. are mentioned.
(F) Lubricants For example, carboxylic acid metal salts, carboxylic acid esters, fatty acid amides and the like can be mentioned.

(G) Inorganic flame retardant Examples of the inorganic flame retardant include aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, basic magnesium carbonate, dolomite, hydrotalcite, calcium hydroxide, barium hydroxide, and tin oxide. Hydrates, hydrates of inorganic metal compounds such as borax, zinc borate, zinc metaborate, barium metaborate, zinc carbonate, magnesium carbonate-calcium carbonate, calcium carbonate, barium carbonate, magnesium oxide, molybdenum oxide, zirconium oxide, oxidation Examples include tin and red phosphorus. These may be used alone or in combination of two or more. Among these, a hydrate of at least one metal compound selected from the group consisting of aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, basic magnesium carbonate, dolomite, and hydrotalcite, particularly aluminum hydroxide, Magnesium hydroxide has an excellent flame retardant effect and is economically advantageous.

(5) Compounding amount of each component In the present invention, the compounding amount of each component is 9 to 22 parts by weight, preferably 10 to 18 parts by weight, more preferably 10 to 18 parts by weight, based on 100 parts by weight of the polypropylene resin. Is 12 to 15 parts by weight. When the blending amount of the flame retardant is less than 9 parts by weight, V0 cannot be achieved as flame retardancy, and when it exceeds 22 parts by weight, it is disadvantageous for economic efficiency, and the molded product becomes sticky.

  On the other hand, the compounding quantity of an antimony compound is 5-15 weight part with respect to 100 weight part of polypropylene resins, Preferably it is 5-11 weight part, More preferably, it is 5-9 weight part. When the blending amount of the antimony compound is less than 5 parts by weight, V0 cannot be achieved as flame retardancy, and when it exceeds 15 parts by weight, it is disadvantageous for economic efficiency.

In the present invention, (a) paraffin oil is not an essential component, but when a two-stage mixing method in which a small amount is first blended with polypropylene resin pellets and then an organic flame retardant and an antimony compound are added to the blend, This is preferable because the uneven accumulation of the flame retardant in the composition can be further prevented. When paraffinic oil is used for this purpose, the blending amount is 0.3 to 1.3 parts by weight, preferably 0.3 to 1 part by weight, more preferably 100 parts by weight of polypropylene resin. 0.4 to 0.6 parts by weight. Addition exceeding the above range is not preferable because the flame retardancy is reduced.
(B) Antioxidant, (c) Ultraviolet absorber, (d) Nucleating agent, (e) Antistatic agent, (f) Lubricant, (g) Inorganic flame retardant, etc. are additionally blended as necessary Is a component to be processed. For the purpose of the present invention, a small amount, for example, 0.01 to 10 parts by weight with respect to 100 parts by weight of the polypropylene resin is used.

2. Method for Producing Flame Retardant Polypropylene Resin Composition The method for blending the polypropylene resin pellet, flame retardant and antimony compound blended in the present invention is not particularly limited and can be blended in any order. For example, first, a flame retardant and an antimony compound are blended and mixed in polypropylene resin pellets to form a three-part mixture, and then the mixture is melt-kneaded. At this time, prior to the mixing step, it is preferable to first mix the polypropylene resin pellets and the paraffinic oil, and then blend the flame retardant and the antimony compound in the second step of the mixing step, and mix the whole. The mixture obtained through the two-stage mixing process has less uneven flame retardant, and can be melt-kneaded without uneven deposition, and the resulting flame retardant polypropylene resin composition is flame retardant. Property effect and heat aging prevention performance are improved.

  Alternatively, batch mixing of an organic flame retardant, an antimony compound, and a paraffinic oil with polypropylene resin pellets can also be exemplified. Even in such an embodiment, the organic flame retardant used in the present invention has a maximum particle size of 100 μm or less, so that uneven accumulation hardly occurs. Furthermore, when adding antioxidant, a ultraviolet absorber, etc., the case where it mixes collectively can be illustrated.

  A known method can be used for the mixing step, and various mixers such as a tumbler, a Henschel mixer, a super mixer, and a super floater can be used.

  In the melt-kneading step, a known method can be used as a method for melt-kneading the mixture, and various melt-kneaders such as a single screw extruder, a twin screw extruder, a continuous kneader, a brabender, and a kneader are used. be able to. After melt-kneading, it is usually sent again to the pelletizing step for commercialization.

  In the present invention, the uneven distribution is used as an index representing the dispersion state of the propylene resin, the flame retardant and the antimony compound in the mixture obtained in the mixing step for obtaining the polypropylene resin composition. Specifically, the mixed sample is put into a hopper, then melt kneaded with an extruder and pelletized with a cutter. About 50 g of pellet samples are sequentially taken out every 5 minutes from the start of the extruder, and the flame retardant ratio of the flame retardant and antimony compound contained in each sample is determined. The average value of the flame retardant ratio (AVG) Then, the variation (CV) is obtained from the standard deviation (σ) by the following equation. When this CV value is 25% or more, it is normally evaluated that “there is uneven distribution”.

    CV (%) = (σ / AVG) × 100

3. Use of flame retardant polypropylene resin composition The flame retardant polypropylene resin composition of the present invention is obtained by melt-kneading a mixture without uneven stacking, so it has excellent flame retardant performance and heat aging prevention performance, Stable quality can be expressed. For this reason, homes such as TV back covers, condenser cases, speaker boxes, refrigerator evaporating dishes, switch parts, lighting equipment parts, warm air heater covers, heating toilet seats, hot shower toilet seat control covers, air conditioner outdoor units, etc. It can be suitably used for equipment parts, automotive fuse boxes, and the like.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation method, particle size measurement, and materials used are as follows.

1. Evaluation method and particle size measurement (1) Unbalance (distribution of distribution)
(I) A predetermined amount of polypropylene resin pellets and paraffinic oil was placed in a 20 L capacity super mixer (manufactured by Kawada, model SM) and mixed for 1 minute, then a predetermined amount of flame retardant and antimony were added, and then mixed for 1 minute. . When paraffinic oil was not used, a predetermined amount of flame retardant and antimony were added directly to the polypropylene resin pellets, and then mixed for 1 minute.
(Ii) The mixed sample was taken out into a bag, and then charged into a hopper of a 30-mm diameter twin-screw extruder (Ikegai Iron Works, PCM30). Thereafter, the mixture was melt-kneaded under a resin temperature of 200 ° C. and further pelletized with a cutter. About 50 g was sampled from the start of the extruder to the end every 5 minutes at the cutter exit. The sample at the start of the start of this sample was X1, and then X2, X3,. This was used as the primary sample for flame retardant amount analysis.
(Iii) A part of the primary sample is a sheet of 50 × 50 × 2.0 mm under conditions of resin temperature 230 ° C., preheating 3 minutes, pressurization 1 MPa, 1 minute, cooling temperature 30 ° C., pressurization 10 MPa, 4 minutes. It was created. Two sheets obtained were overlapped and the flame retardant (elemental bromine) was analyzed and quantified by fluorescent X-ray analysis.
For samples X1 to Xn, the amount of flame retardant was determined, the average value (AVG) and the standard deviation (σ) were determined, and the variation (CV) was determined by the following equation.

CV (%) = (σ / AVG) × 100
The details of the fluorescent X-ray analysis are as follows.
A fluorescent X-ray analyzer (manufactured by Rigaku Denki Kogyo Co., Ltd., Model 3270) was used, and the spectroscopic crystal was lithium fluoride. As an analysis of flame retardants, elemental bromine was quantified. In the analysis, first, a calibration curve sample with a known flame retardant concentration is prepared, and the intensity of fluorescent X-rays is measured. A regression graph between the X-ray intensity and the flame retardant concentration is created and the correlation is confirmed, and then a linear regression equation is obtained. Next, a fluorescent X-ray measurement sample was prepared and the intensity of the fluorescent X-ray of bromine element was measured. The concentration of the target flame retardant was obtained from the above regression equation.

(2) Heat aging performance The following test pieces were prepared and measured under conditions of 150 ° C. in accordance with JIS K7212-B. The test piece was prepared in a 200 × 200 × 0.5 mm sheet under conditions of preheating 7 minutes at a resin temperature of 200 ° C., pressurization of 1 MPa, 3 minutes, and a cooling temperature of 30 ° C. and pressurization of 12 MPa for 3 minutes. did. A test piece having a width of 35 mm and a length of 65 mm was cut out from a portion having a uniform thickness with no abnormality from this sheet. For attaching the test piece to the rotating drum of a heat aging tester (150 ° C., gear oven), an aluminum clip was used, and the test piece was attached via glass tape so that the test piece was not directly touched by aluminum.

  After the sample was mounted on the rotating drum of the gear oven, the presence or absence of the deterioration (cracking and discoloration) of the test piece was observed at every elapsed time. Observation was carried out twice a day (example of observation time: 8:00 am and 16:00 pm), and the time until the occurrence of deterioration was measured to determine the heat aging time.

(3) Flame Retardancy Create and evaluate the test piece specified in UL94 Flame Retardancy Test Method (Underwriters Laboratories) “Burn Testing of Plastic Parts of Equipment”. did. The test was performed 20 times, and the number of cotton ignitions was counted.

(4) Particle size of flame retardant (particle size range of 44 to 2800 μm)
Using a standard sieve (mesh opening 2800, 1680, 710, 250, 149, 105, 74, 44 μm) in accordance with JIS Z8801, about 300 g of the stacked flame retardants are put in the uppermost order and covered. This was fixed to a low-tap type sieve shaker and shaken for 15 minutes under the conditions of a sieve width of 25 mm, a shaking number of 290 rpm, and a hammer hitting number of 156 rpm. The mass of the flame retardant present on each sieve was determined, and the mass distribution was used as the particle size distribution. From this particle size distribution, the particle size corresponding to 50% was defined as the average particle size. Further, the uppermost part of the sieve was determined as the maximum particle size.

(5) Flame retardant particle size (particle size range of 0.02 to 1000 μm)
It measured using the laser diffraction (scattering type) particle size distribution measuring apparatus (Horiba, LA920 type | mold). For the measurement, use pure water as the dispersion medium, adjust the laser transmittance of the device to 100%, then put the sample so that the laser transmittance is 80 to 90% while applying ultrasonic waves, and then select the measurement Carried out. A measurement result is obtained as an integrated amount (%) of the passage for each particle size between 0.02 and 1000 μm. The minimum particle size of the accumulated amount of passage was determined as the minimum particle size, the particle size of the accumulated amount of 50% passage was determined as the average particle size, and the maximum value of the accumulated amount of passage was determined as the maximum particle size.

2. Materials used (1) Polypropylene resin (PP-1):
Propylene / α-olefin block polymer pellets (α-olefin content 8 wt%, MFR 30 g / 10 min., Manufactured by Nippon Polypro, Novatec PP BC03B)
(2) Polypropylene resin (PP-2):
Propylene homopolymer pellets (MFR 25 g / 10 min., Manufactured by Nippon Polypro Co., Ltd., Novatec PP MA03)

(3) Flame retardant (FR-1):
Bis (3,5-dibromo-4-hydroxyphenyl) sulfone (fine particle product having an average particle size of 5.5 μm, a maximum particle size of 60 μm, and a minimum particle size of 1 μm. An example of NFPP manufactured by Arteco Chemical Co., Ltd. (Shown in FIG. 1)
(4) Flame retardant (FR-2):
Bis (3,5-dibromo-4-hydroxyphenyl) sulfone (average particle size 1672 μm, maximum particle size 2800 μm, minimum particle size 149 μm coarse product. Marunishi Yuka Kogyo Co., Ltd. Nonen PR 2. The particle size distribution is shown in Table 1. .)
(5) Flame retardant (FR-3):
Bis (3,5-dibromo-4-hydroxyphenyl) sulfone (fine-grained product having an average particle size of 470 μm, a maximum particle size of 1200 μm, and a minimum particle size of 149 μm. A pulverized product of Nonnen PR2 manufactured by Maruhishi Oil Chemical Co., Ltd. Table 1 shows the particle size distribution. Pointing out toungue.)
(6) Flame retardant (FR-4):
2,2-bis (3,5-dibromo-4- (2,3-dibromo) propoxyphenyl) propane (fine particle product having an average particle size of 13 μm, a maximum particle size of 74 μm, and a minimum particle size of 1 μm. FG3100 manufactured by Teijin Chemicals Ltd. is JIS (Sieving using standard mesh 200 mesh. An example of improved etherified tetrabromobisphenol A (removed product of large particle size powder). The particle size distribution is shown in Table 1.)
(7) Flame retardant (FR-5):
2,2-bis (3,5-dibromo-4- (2,3-dibromopropoxyphenyl) propane (fine particle product having an average particle size of 15 μm, a maximum particle size of 150 μm, and a minimum particle size of 1 μm. FG3100 manufactured by Teijin Chemicals Ltd. Etherification An example of tetrabromobisphenol A. The particle size distribution is shown in Table 1.)

(8) Antimony compound:
Antimony trioxide (Suzuyu Chemical Co., Ltd., Fire Cut AT3, average particle size 2.2 μm)
(9) Paraffinic oil:
Liquid paraffin (kinematic viscosity 31 mm ² / S, molecular weight 420, manufactured by Idemitsu Kosan Co., Ltd., PS-32)

[Example 1]
(1) Mixing step As a polypropylene resin pellet, 100 parts by weight of PP-1 and 0.5 part by weight of paraffinic oil are put into a super mixer (manufactured by Kawada, model SM) with a capacity of 20 L and mixed for 1 minute at a rotation speed of 750 rpm (First mixing step). Then, 12 parts by weight of FR-1 as a flame retardant, 6 parts by weight of antimony trioxide, and pentaerythrylyltetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] as a stabilizer 0.1 part by weight and 0.1 part by weight of tris (2,4-di-t-butylphenyl) phosphite were additionally added and mixed at 750 rpm for 1 minute.
(2) Melt-kneading step A sample mixed with a flame retardant was subjected to a resin temperature of 200 ° C., a screw rotation speed of 200 rpm, and a discharge rate of about 10 to 13 kg / h using a twin screw extrusion kneader (PCM30, manufactured by Ikekai Tekko Co., Ltd.) having a diameter of 30 mm. The mixture was melt-kneaded to form a cylindrical pellet having a diameter of about 2.5 mm and a length of 3.0 mm. At the time of pelletization, about 50 g was sampled every 5 minutes from the start of the cutter (extruder outlet sample), and this was used as a flame retardant analysis sample.
(3) Evaluation After the obtained pellet-shaped polypropylene resin composition was mixed well, the above-described methods were used to evaluate the uneven distribution (variation CV), heat aging resistance and flame retardancy of the flame retardant. The results are shown in Table 2.

[Example 2]
Except for replacing the flame retardant (FR-1) used in Example 1 with the flame retardant (FR-4), the situation of uneven stacking, heat aging resistance and flame retardancy were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Example 1]
Except that the flame retardant (FR-1) used in Example 1 was replaced with the flame retardant (FR-2), the uneven stacking situation, heat aging resistance and flame retardancy were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Example 2]
Except for replacing the flame retardant (FR-1) used in Example 1 with the flame retardant (FR-3), the uneven stacking situation, heat aging resistance and flame retardancy were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Comparative Example 3]
Except that the flame retardant (FR-1) used in Example 1 was replaced with the flame retardant (FR-5), the uneven stacking situation, heat aging resistance and flame retardancy were evaluated in the same manner as in Example 1. The results are shown in Table 2.

From the discussion in Table 2, the following matters became clear.
(1) Although both Example 1 and Comparative Example 1 use bisphenol S, Example 1 uses a flame retardant (FR-1) having the particle size distribution of the present invention, and Comparative Example 1 has a large particle size. The flame retardant (FR-2) containing a product is used. Although the amount of flame retardant contained in polypropylene is equivalent on average (Example 1 is AVG = 10.6, Comparative Example 1 is AVG = 10.4), the variation is that of Example 1. Is 6.6, and Comparative Example 1 has a significant difference of 39.4 . As a result, the heat aging resistance of Example 1 was 1032 hours, while that of Comparative Example 1 was reduced to 670 hours. Thus, it can be seen that the difference in the particle size distribution of the flame retardant greatly affects the material properties of the resin composition.
(2) Comparative Example 2 is data demonstrating the critical value of the maximum particle size. Even if it is a pulverized product, if the maximum particle size does not fall below the critical value, the effect of the present invention cannot be expressed.
(3) Both Example 2 and Comparative Example 3 use bisphenol A. In Example 2, the flame retardant (FR-4) having the particle size distribution of the subject of the present invention is used, and in Comparative Example 3, the flame retardant (FR-5) containing a large particle size product is used. The same discussion shows that the heat aging resistance is improved when the particle size distribution of the flame retardant is lower than the prescribed value of claim 1.

  Flame retardancy and heat aging resistance can be improved without increasing the amount of antioxidants, heat stabilizers and the like. The excellent mechanical properties of polypropylene resin can be expressed, and it can be used for home appliance parts, housing equipment parts, automobile parts and the like.

2 is a graph showing the particle size distribution of an organic flame retardant (FR-1) used in Example 1. FIG.

Explanation of symbols

1 is a bar graph showing the abundance ratio [frequency] of particles having the particle diameter (left vertical axis:%).
2: This is a curve showing the cumulative weight ratio from the particles having the minimum particle size to the particles having the particle size [integrated portion of passage] (right vertical axis:%).

Claims (7)

Paraffin oil 0.3 to 1.3 parts by weight is blended with 100 parts by weight of polypropylene resin pellets , and then 9 to 22 parts by weight of an organic flame retardant having a maximum particle size of 100 μm or less and 5 to 5 of antimony compound. A flame-retardant polypropylene resin composition obtained by blending 15 parts by weight and further melt-kneading the blend. The flame retardant polypropylene resin composition according to claim 1, wherein the minimum particle size of the organic flame retardant is 0.5 μm or more. The flame retardant polypropylene resin composition according to claim 1 or 2, wherein the organic flame retardant is a halogenated aromatic compound. The flame retardant polypropylene resin composition according to claim 3, wherein the halogenated aromatic compound is etherified tetrabromobisphenol S or etherified tetrabromobisphenol A. The flame retardant polypropylene resin composition according to claim 1, wherein the paraffinic oil has a kinematic viscosity of 30 to 450 mm ² / S (40 ° C.). The flame-retardant polypropylene resin composition according to any one of claims 1 to 5, wherein after the melt-kneading, the pelletized step is performed again to form a pellet. The flame retardant polypropylene resin composition according to any one of claims 1 to 6, wherein an uneven distribution (variation) of the flame retardant content in the polypropylene resin composition is 16% or less.

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