JPH1077378A - Dripping inhibitor and flame-retardant resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject additive which can give drip-inhibiting properties to an easily combustible thermoplastic resin, when it combusts, by using the particles of polytetrafluoroethylene having specific ranges of average particle size, apparent density and standard specific weight. SOLUTION: This additive comprises polytetrafluoroethylene particles prepared by suspension polymerization and has an average particle size of 1-1,000μm, an apparent density of 0.20-1.00g/cm<3> , and a standard specific gravity of 2.13-2.23 and can give dripping prevention properties to an easily combustible thermoplastic resin. A flame-retardant resin composition can be prepared by adding this dripping prevention agent in an amount of 1-5 pts.wt. per 100 pts.wt. of an easily combustible thermoplastic resin (preferably a polycarbonate resin) and 0.001-40 pts.wt. of a flame retardant to the easily combustible thermoplastic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-drip agent for imparting an anti-drip property to a flammable thermoplastic resin when burned, and a workability comprising the resin, the anti-drip agent and a flame retardant. The present invention relates to a flame-retardant resin composition having good flame retardancy. In addition, the anti-drip agent and the flame-retardant resin composition of the present invention are suitably used for molded articles in the field of home appliances and OA equipment.

[0002]

2. Description of the Related Art Conventionally, thermoplastic resin molded products used in homes, offices, factories, etc., such as electric appliances and O.D.
In equipment A, most of the thermoplastic resin is flammable,
Usually, there is a demand for a device for adding a flame retardant to the molding raw material to improve the flame retardancy of the resin molded product.

[0003] However, many flame retardants have an effect of making it difficult to burn, but once they start burning, the effect of preventing the thermoplastic resin from becoming liquid and preventing it from dripping while burning and spreading the fire is poor. .

On the other hand, for example, Underwriters' L
In the standard of aboratories (hereinafter abbreviated as UL) 94, a class (V-1, V-0) with high flame retardancy is provided as a grade of a fire test, as long as it has an anti-drip property. . In addition, polytetrafluoroethylene (PTFE) is used to prevent drip and further enhance safety.
Is melt-mixed with a flammable thermoplastic resin together with a flame retardant.

[0005] For example, in Japanese Patent Application Laid-Open No. 50-44241, a flammable thermoplastic resin, a flame retardant, and a non-flammable fiber are used together with P
Japanese Patent Publication No. 59-36657 discloses a composition in which TFE is added in an amount of 0.1 to 5% (weight%, the same applies hereinafter), and a composition in which a flame retardant and PTFE are added to polyphenylene ether or a styrene resin is disclosed in In JP-A-38418, a flame retardant of an organic alkali metal salt and / or an organic alkaline earth metal salt is added to an aromatic polycarbonate in an amount of 0.01 to 10%.
And ASTM D-1457 Type 3 PTFE 0.01
To 2.0% by weight is disclosed in Japanese Patent Publication No. 62-5862.
No. 9 discloses a composition obtained by adding a flame retardant and PTFE to an acrylonitrile-butadiene-styrene copolymer (ABS). In addition, regarding a polymer alloy of an aromatic polycarbonate and a styrene-based resin,
In JP-60181, compositions containing an organic bromine compound, a flame retardant such as an antimony or bismuth compound and PTFE are disclosed in JP-A-61-55145 and JP-A-61-55145.
JP-A-261352, JP-A-63-278961, JP-A-2-32154 and the like disclose a composition in which PTFE is added together with a phosphorus compound.
No. 9 discloses a composition in which PTFE is added together with an alkali metal salt of an organic or inorganic acid. Regarding polyamides, for example, Japanese Patent Application Laid-Open No. 5-186686 discloses that a PTF is used together with a flame retardant such as a phosphate ester.
A composition to which E is added is disclosed.

As PTFE for drip prevention, a powder obtained by coagulating and drying a latex obtained by emulsion polymerization of tetrafluoroethylene (usually called PTFE fine powder and having a standard specific gravity (SSG) of 2.14 to 2 .23
And an aqueous dispersion (usually PTF) produced by concentrating and stabilizing a latex by adding a surfactant to the latex, which is classified into ASTM D-1457 type 3).
E-dispersion is used (for example, Japanese Patent Publication No. 1-60181, JP-A-61-55145).
JP-A-61-261352, JP-A-63-278
961, JP-A-2-32154, JP-A-61-12
No. 7,759, each uses an aqueous dispersion).
The fine powder is usually processed into a tube, pipe or tape by paste extrusion, while the dispersion is processed into various articles by impregnation and painting, both of which have the heat resistance, non-adhesiveness and sliding properties of PTFE. It is used for applications that take advantage of its properties, water and oil repellency, electrical properties, corrosion resistance, weather resistance, and the like. The fine powder has an average particle size obtained by emulsion polymerization of 0.05 to 1.0 μm.
m is a powder formed by aggregating PTFE fine particles, and the dispersion is a state in which the fine particles are dispersed in water, and each of them basically contains a unit of PTFE fine particles.

[0007] The drip prevention function is due to the fact that the PTFE particles have the property of easily fibrillating. That is, when the thermoplastic resin is mixed with the fine powder or the dispersion in a molten state, the PTFE fine particles are fibrillated by the shearing force of the mixing, and the fibrils are dispersed in the thermoplastic resin. Since the fibrils remain dispersed in the final molded article of the thermoplastic resin, dripping during combustion is prevented.

However, in order to mix the flammable thermoplastic resin with PTFE, the powder, pellets or liquid of the flammable thermoplastic resin is mixed with the fine powder or the dispersion before the melt mixing. Need to match. However, the fine powder has a tendency to fibrillate even at room temperature, so that the flowability of the powder is inferior, and there is a problem in workability when mixing. The dispersion is easy to mix with each other when the flammable thermoplastic resin is an aqueous dispersion, but if the resin is powder or pellets, unnecessary water in the dispersion is mixed after mixing. And a step of removing the surfactant is required.

Further, when the flammable thermoplastic resin is kneaded with PTFE in a molten state in a kneader, the melt viscosity often rises due to excessive fibrillation and the load on the kneader increases. If there is too much. In some cases, due to excessive fibrillation, PTFE is not entangled with each other and is not uniformly dispersed in the thermoplastic resin. In such a case, the strand extruded from the kneading machine is cut on the way, and the kneading workability is significantly reduced.

[0010] Poor dispersibility due to aggregation of fibrils in a flammable thermoplastic resin causes poor appearance of a molded article, and is particularly noticeable in a thin-walled article.

When a flame-retardant thermoplastic resin is made flame-retardant, a flame retardant is indispensable. However, in general, when a flame retardant is used, the physical properties of the resin tend to be reduced, and the cost is high economically. become. Although the PTFE fine particles are relatively expensive, but added in a small amount, if the dispersibility of the fine particles in the resin is improved, the overall flame retardancy can be reduced even if the amount of the flame retardant used is reduced to some extent. It is considered that cost reduction can be achieved without lowering the cost.

On the other hand, unlike PTFE fine particles constituting powder of ASTM D-1457 type 3, a proposal has been made to solve the above-mentioned problem by using PTFE-based fine particles having a specific structure as an additive. I have.

For example, in WO94 / 1475,
A core-shell structured fine particle having a core-shell structure, wherein the core of the fine particle is fibril-forming PTFE, while the shell portion is a non-fibril-forming vinylidene fluoride resin (PVDF). Is effective. In JP-A-1-247408 and JP-A-5-279579, the core is modified by copolymerizing PTFE and the shell is hexafluoropropylene, perfluorobutylethylene, perfluoromethylvinylether or perfluoropropylvinylether. PT
FE core-shell structured microparticles are disclosed.

However, the fine particles described in the above-mentioned WO 94/1475 and JP-A 1-247408 have significantly higher workability and dispersibility when added to a flammable thermoplastic resin than conventional PTFE. Although it has been improved, it still leaves insufficient points. WO94 / 1475
When the fine particles described in JP-A No. 10-205,086 are added to a flammable thermoplastic resin to form a flame-retardant composition, adverse effects due to PVDF introduced as a shell may be caused. In the conventional flame retardant composition to which PTFE is added, dispersed PT
FE has an effect other than the anti-drip property, for example, an effect of improving the releasability from a mold at the time of molding and the frictional characteristics of a molded product. However, PVDF loses such effects. Further, depending on the flame retardant, PVDF chemically changes and causes unnecessary coloring.

Further, the fine particles described in Japanese Patent Application Laid-Open No. 1-247408 are not sufficient in terms of the essential anti-dripping property, even though the workability and the dispersibility are greatly improved. That is, in the specification, it is stated that the fine particles are suitable for blending with a resin or an elastomer, but the main effect is that the fine particles are deformed when kneaded with the resin or the elastomer. The purpose of the present invention is to improve the mechanical properties of resins and elastomers by plate-like particles, and specific examples of anti-drip properties are given only for the example of ethylene-tetrafluoroethylene copolymer (ETFE). Since the fine particles are platelet-shaped particles, the addition amount must be larger than usual in order to obtain a sufficient anti-drip property.

As described above, anti-drip agents are being developed to improve PTFE fine powder obtained by emulsion polymerization.

On the other hand, PTFE powder includes PTFE molding powder obtained by suspension polymerization (standard specific gravity is in the range of 2.13 to 2.23, and ASTM D-1).
457 types 4, 6, and 7). Since this molding powder is generally difficult to fibrillate, it has good operability at the time of mixing, but has been regarded as unsuitable as an anti-drip agent which requires fibrillation at the time of mixing and molding, and has been excluded from development.

[0018]

SUMMARY OF THE INVENTION The present inventors have made intensive studies to use PTFE molding powder, which hardly fibrillates at room temperature, as an anti-drip agent. As a result, PTFE molding powder and flammable thermoplastic resin were used. It has been found that when the resin is kneaded in a molten state and shearing force is applied, fibrillation occurs and the drip preventing ability is developed, and the present invention has been completed.

[0019]

That is, the present invention relates to PTFE particles obtained by suspension polymerization and having an average particle size of 1%.
~ 1000 µm, apparent density 0.20-1.00 g /
The present invention relates to an anti-drip agent for imparting anti-drip properties to a flammable thermoplastic resin, comprising particles having a standard specific gravity (SSG) of 2.13 to 2.23 cm ³ .

The present invention also relates to a flammable thermoplastic resin 100
Parts (parts by weight; the same applies hereinafter) and the drip preventing agent 0.0
The present invention relates to a flame-retardant resin composition comprising 1 to 5 parts and 0.001 to 40 parts of a flame retardant.

The flammable thermoplastic resin is preferably at least one selected from the group consisting of a polycarbonate resin, a polystyrene resin, a polyester resin and a modified polyphenylene ether.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The PTFE molding powder used in the present invention has an average particle size of 1 to 1000 μm, preferably 10 to 8 among known molding powders.
00 μm, apparent density 0.20-1.00 g / c
m ³ , preferably 0.25 to 0.95 g / cm ³ , standard specific gravity (SSG) of 2.13 to 2.23, preferably 2.1
4 to 2.20.

The PTFE molding powder includes not only a homopolymer suspension of tetrafluoroethylene but also various modified PTFE molding powders. As such a modified PTFE molding powder, for example, a modified monomer such as described in JP-B-40-10428, JP-B-50-31524, JP-B-54-46794 or WO95 / 16126 can be used. To 1.0% by weight. As the modified monomer, for example, a fluoroolefin such as chlorotrifluoroethylene, hexafluoropropylene, fluoroalkylethylene, or perfluoro (alkyl vinyl ether) is preferable. In addition, PTFE molding powder obtained by a suspension polymerization system to which a small amount of a dispersant is added (Japanese Patent Publication No. 5-8049)
0 publication). Furthermore, granulated PTFE molding powder obtained by pulverizing and granulating the particles obtained by the suspension polymerization (Japanese Patent Publication No. 44-22619, Japanese Patent Publication No. 58-14291, Japanese Patent Publication No. 3-69927, Japanese Patent Publication No. No. 39105).

The PTFE used in the present invention has a standard specific gravity (S
SG) (ASTM D-1457) 2.13 to 2.2
3, preferably 2.14 to 2.20. The smaller the standard specific gravity is, the higher the molecular weight is. If it exceeds 2.23 (the molecular weight is small), fibrillation becomes insufficient. Even though the standard specific gravity is small (even if the molecular weight is large), it is not related to the property of fibrillation, so the lower limit of the standard specific gravity depends on whether or not the production is easy. The standard specific gravity is 2.
The number average molecular weight of PTFE of 14 to 2.20 is about 15 × 10 ^{5 to} 9 × 10 ^{6 as} calculated by the following equation.

Formula: log ₁₀ (number average molecular weight) = 31.8
3-11.58 × (standard specific gravity) Examples of the flammable thermoplastic resin of the present invention include polyolefin resins (polyethylene, polypropylene, polymethylpentene, etc.), polyvinyl chloride, and polystyrene resins (polystyrene, AS, ABS, etc.). ), Polycarbonate (PC) resin (PC, PC alloy resin such as PC / ABS), polyamide resin (nylon, wholly aromatic polyamide, etc.), polyester resin (polybutylene terephthalate, polyethylene terephthalate, wholly aromatic) Polyester, etc.), acrylic resin (polymethyl methacrylate, polyacrylonitrile, etc.), polyacetal, polyether ether ketone, modified polyphenylene ether, polyarylene sulfide resin, polysulfone resin, and other various polymer alloys Etc., and the like. In particular, applications requiring a high level of flame retardancy, such as home appliances and OA equipment, used in housings and various mechanical parts, such as polycarbonate resins such as PC and PC alloys, polystyrene resins, polybutylene terephthalate, and polyethylene terephthalate. When a resin such as a polyester resin or a modified polyphenylene ether is used, an excellent drip prevention effect is exhibited.

The amount of the anti-drip agent of the present invention in the flammable thermoplastic resin is 0.01 to 5 parts, preferably 0.03 to 2 parts, per 100 parts of the resin.
If the amount is less than 0.01 part, the desired anti-drip property tends not to be obtained. If the amount exceeds 5 parts, the anti-drip property, the releasability from the mold, and the friction characteristics of the molded article are improved, but the dispersion of the inhibitor in the resin tends to occur.

The flame retardant of the present invention includes, for example, nitrogen, phosphorus,
Representative examples include compounds containing Group 5B of the periodic table, such as antimony and bismuth, and compounds containing halogen compounds of Group 7B. Examples of the halogen compound include aliphatic, alicyclic, and aromatic organic halogen compounds such as brominated tetrabromobisphenol A (TBA), decabromodiphenyl ether (DBDPE), octabromodiphenyl ether (OBDPE), TBA epoxy / phenoxy oligomer, and bromine. Crosslinked polystyrene, chlorine-based chlorinated paraffin, perchlorocyclopentadecane, and the like. Examples of the phosphorus compound include a phosphate ester and a polyphosphate. The antimony compound is preferably used in combination with a halogen compound, and examples thereof include antimony trioxide and antimony pentoxide. In addition, aluminum hydroxide, magnesium hydroxide, and molybdenum trioxide can also be used. These flame retardants can be arbitrarily selected in at least one kind and the amount thereof depending on the kind of the flammable thermoplastic resin, but are not limited to these. Usually, the compounding amount of the flame retardant is 0.001 to 40 parts, preferably 0.01 to 30 parts per 100 parts of the resin. When the flame retardant is less than 0.001 part, the flame retardant effect tends to be insufficient. Yes, if it exceeds 40 parts, it is not economical and the mechanical properties (such as impact resistance) of the resin composition tend to decrease.

The flame-retardant resin composition of the present invention comprises a flammable thermoplastic resin, the anti-drip agent of the present invention, and a flame retardant.
The composition can be manufactured by blending each component by a known method, but the order of blending, whether to blend in a powder state or a dispersion state, or the type of a blending machine and a combination thereof are known in the art. According to the method.

The flame-retardant resin composition of the present invention contains, in addition to the flame retardant and the anti-drip agent, known additives such as an ultraviolet absorber, an antioxidant, a pigment, a molding aid, calcium carbonate,
Glass fibers and the like can be added as needed.

Next, the anti-drip agent and the flame-retardant resin composition of the present invention will be specifically described based on examples and production examples, but the present invention is not limited to these.

Example 1 100 parts of an ABS resin (trade name: ABS15, manufactured by Nippon Synthetic Rubber Co., Ltd.) and PETE molding powder (trade name: Polyflon TFE M-12, manufactured by Daikin Industries, Ltd.) as a flammable thermoplastic resin. Average particle size 25 μm, apparent density 0.29 g / cm ³ , standard specific gravity 2.155) 0.2
6 parts and 22.5 parts of a brominated epoxy resin (trade name: YDB-408 manufactured by Toto Kasei Co., Ltd.) as a flame retardant and antimony trioxide (trade name: ATOX manufactured by Nippon Seiko Co., Ltd.)
-S) In a tumbler, 7.0 parts of a premix was preliminarily mixed at room temperature for 10 minutes, and charged in a screw feeder of a twin-screw extruder having a diameter of 40φ. As conditions for kneading and extrusion,
Extrusion temperature 210 ° C, screw rotation speed 130 rotations / minute,
A pellet-shaped flame-retardant resin composition of the present invention was obtained at a supply rate of 8 kg / hour. The workability at this time was evaluated in the following points.

From the composition, a strip test piece (length 5 inches, width 1/2 inch, thickness 1/8 inch) was prepared using an injection molding machine (Sumitomo Heavy Industries, Ltd., trade name SG50). Then, the following UL94 combustion test was performed to examine the flame retardancy. Table 1 shows the results.

Workability: Comprehensively evaluated by the supply stability of the premixed raw material charged into the screw feeder of the extruder and the discharge stability of the strands from the extruder, and the workability was evaluated as good. (+), When the supply of the raw material by the bridge was interrupted or the strand was cut, it was regarded as defective (-).

Flame retardancy: Conducted in accordance with UL94 (plastic flammability test method), and based on the results of five test pieces, the materials were UL94V-0, UL94V-1, and UL94V-
Evaluation was made in three stages of 2. The UL94V class and the criteria are as follows.

UL94V-0: (a), (c),
(E), (f) and (h) must be satisfied. UL94V-1: (b), (d), (e), (g) below
And (h) are both satisfied. UL94V-2: All of the following (b), (d), (g) and (h) should be satisfied.

(A): It does not keep burning for more than 10 seconds after one flame contact. (B): Does not burn for more than 30 seconds after one flame contact. (C): The total combustion time after the flame contact of 10 times in total of 5 times each of 5 tubes does not continue burning within 50 seconds. (D): The total burning time after 10 times of flame contact, 5 times each for 2 times, does not continue to burn within 250 seconds. (E): Do not burn absorbent cotton 12 inches below by dropping a fireball. (F): Glowing time after the second flame contact is within 30 seconds. (G): The glowing time after the second flame contact is within 60 seconds. (H): Do not burn up to the clamp.

Example 2 In Example 1, the polytetrafluoroethylene TFE M-3 manufactured by Daikin Industries, Ltd. was used as the PTFE molding powder.
3 (average particle size 250 μm, apparent density 0.83 g / cm
³ , a standard specific gravity of 2.154) was obtained in the same manner as above, to obtain a flame-retardant resin composition of the present invention, and a strip test piece was prepared therefrom. The same test as in Example 1 was performed. Table 1 shows the results.

Example 3 In Example 1, a polycarbonate resin (trade name Panlite L, manufactured by Teijin Chemicals Ltd.) was used as the flammable thermoplastic resin.
-1225W) 100 parts, 0.5 part of PTFE molding powder (TFE-33) used in Example 2, and tetrabromobisphenol A (trade name: Fireguard FG-700, manufactured by Teijin Chemicals Ltd.) as a flame retardant.
0) A flame-retardant resin composition of the present invention was obtained in the same manner except that 5.0 parts was used and the extrusion temperature was 290 ° C. Further, a strip test piece was prepared from this, and the same UL94 as in Example 1 was used.
A combustion test was performed. Table 1 shows the results.

Comparative Example 1 In Example 1, PTFE fine powder obtained by emulsion polymerization (manufactured by Daikin Industries, Ltd., trade name: Polyflon TFE F-104; average particle size: 500 μm, apparent density: 0.45 g / cm ³ , standard specific gravity) Except for using 2.173), a pellet-like flame-retardant resin composition was obtained under the same composition and kneading and extrusion conditions. From this, a strip test piece was prepared, and the same test as in Example 1 was performed. Table 1 shows the results.

[0040]

[Table 1]

As is clear from Table 1, the anti-drip agent of the present invention has sufficient drip prevention and excellent workability.

EXPERIMENTAL EXAMPLE 1 The following experiment was conducted to examine the workability in more detail.

Example 1 (Polyflon TFE M-12) was added to 1.2 kg of the polycarbonate resin used in Example 3.
Or Examples 2-3 (Polyflon TFE M-33)
60 g of the PTFE molding powder used in Example 1 or the PTFE fine powder (Polyflon TFE F-104) used in Comparative Example 1 was mixed and shaken sufficiently in a polyethylene bag, followed by mixing.
(Length 15 cm × width 3 cm × thickness 2 mm. The end face is cut at an angle of 45 degrees) into a stainless steel stirring tank 1 equipped with a stirrer 2 having three stages and a temperature of 30 ° C.
The mixture was stirred at a stirring speed of 60 rpm for 60 minutes to apply a shearing force to the mixed powder.

FIG. 2 shows the change over time in the stirring torque at this time. Further, the state of the powder adhered to the stirring blade after the stirring was completed, and the obtained powder was sieved with a 10-mesh sieve. Table 2 shows the amount remaining on the sieve.

[0045]

[Table 2]

As is clear from Table 2, the PTFE molding powder used in the present invention is less likely to be fibrillated by the shearing force applied from the stirring blade at normal temperature than PTFE fine powder, and is less likely to be aggregated by fibrillation. Recognize. This result shows that the anti-drip agent of the present invention eliminates the instability of the raw material supply due to aggregation of the mixed powder during premixing and aggregation in the spring feeder when producing a flame-retardant resin. Is shown.

[0047]

According to the present invention, it is possible to provide an anti-drip agent excellent in workability in kneading and extruding with a flammable thermoplastic resin.

[Brief description of the drawings]

FIG. 1 is a partially cutaway schematic perspective view of a stirring tank used in Experimental Example 1.

FIG. 2 is a graph showing the change over time of the stirring torque measured in Experimental Example 1.

[Explanation of symbols]

 1 stirring tank 2 stirring device 3 stirring blade

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location // (C08L 101/00 27:18)

Claims (3)

[Claims] 1. Polytetrafluoroethylene particles obtained by suspension polymerization, having an average particle size of 1 to 1000 μm,
An anti-drip agent comprising particles having an apparent density of 0.20 to 1.00 g / cm ³ and a standard specific gravity of 2.13 to 2.23 for imparting anti-drip properties to a flammable thermoplastic resin. 2. The anti-drip agent according to claim 1, wherein the flammable thermoplastic resin is at least one selected from the group consisting of a polycarbonate resin, a polystyrene resin, a polyester resin and a modified polyphenylene ether. 3. A flame-retardant resin composition comprising 100 parts by weight of a flammable thermoplastic resin, 0.01 to 5 parts by weight of the anti-drip agent according to claim 1, and 0.001 to 40 parts by weight of a flame retardant. .