JP5227880B2 - Production method of flame retardant film of polycarbonate resin - Google Patents

Description

  The present invention relates to a method for producing a polycarbonate resin flame-retardant film.

  Polycarbonate resins are known to be excellent in impact resistance, heat resistance, electrical characteristics, dimensional stability, etc., have self-extinguishing properties, and are relatively incombustible. For this reason, it is used in resin casings that constitute OA equipment, information / communication equipment, electrical / electronic equipment, household electrical appliances, lithium ion secondary batteries, and the like.

  These devices are required to be lightweight, small and thin, and from the viewpoint of environmental problems and effective use of resources, the resin casing is also required to be suitable for recycling. When recycling is assumed, it is desirable that the resins constituting the casing are all the same type. Therefore, it is preferable that the resin casings of various devices and the resin film base materials such as labels, seals, decals, and name plates attached thereto are made of the same resin.

  Against the backdrop of such circumstances, the film to be affixed to these devices having a polycarbonate resin casing is made of polycarbonate resin, and is thinner and has high flame retardancy. Required.

  In addition to polycarbonate resin, the resin used for the casing of equipment is acrylonitrile / butadiene / styrene copolymer resin (ABS), polystyrene, impact polystyrene, modified polyphenylene ether, polyamide, polyester, polylactic acid, and alloys thereof. Etc. are used. As a method of making these resins flame retardant, for example, a method of blending, for example, a compound containing bromine or chlorine, antimony oxide or the like as a flame retardant has been known.

  However, these flame retardants are concerned about adverse effects on the environment in terms of toxic gases and smoke generated during combustion. Therefore, a flame retarding method that does not use such a flame retardant has been studied. For example, methods using a red phosphorus flame retardant instead of these flame retardants are disclosed in, for example, Patent Documents 1 to 4. Further, Patent Document 5 discusses a method for imparting flame retardancy without using any compound containing bromine or chlorine, antimony oxide, or red phosphorus.

JP-A-48-85642 JP 7-53779 A JP 2000-297187 A JP 2000-119503 A International Publication No. 05/103155 Pamphlet

However, even if the techniques disclosed in Patent Documents 1 to 4 are effective for making a three-dimensional molded article molded by injection molding or the like flame-retardant, it is sufficient for making a thin film flame-retardant. In some cases, the effect could not be obtained.
Moreover, in the technique of patent document 5, since the flame retardance of a film is dependent on the orientation of a film, sufficient flame retardance is not obtained depending on the cutting direction at the time of cutting out a test piece from a film, ie, a flame retardant. The material has anisotropy.

  The present invention has been made in view of the above circumstances, and has a thickness of 30 to 300 μm in a polycarbonate resin-based flame retardant film which stably has excellent flame retardancy without anisotropy and has excellent appearance and mechanical properties. Is to be manufactured with good moldability.

The method for producing a polycarbonate resin flame-retardant film of the present invention includes a resin composition preparation step of preparing a resin composition in which a polycarbonate resin, a stabilized red phosphorus flame retardant, and polyfluoroethylene are blended. An extrusion process for forming an extruded film having a thickness of 30 to 300 μm by extruding the resin composition, and the stabilized red phosphorus is added to 100 parts by mass of the polycarbonate resin. The flame retardant is compounded in an amount of 0.8 to 8 parts by mass as red phosphorus, the polyfluoroethylene resin is compounded in an amount of 0.05 to 1 part by mass, and the draw ratio in the extrusion process is 1.05 to 33. It is characterized by being.
In the resin composition preparation step, after preparing a masterbatch containing a polycarbonate resin and a stabilized red phosphorus flame retardant, and a masterbatch containing a polycarbonate resin and a polyfluoroethylene resin, respectively, It is preferable to mix the master batch.

  According to the present invention, a polycarbonate resin-based flame-retardant film having a thickness of 30 to 300 μm, which is stably provided with excellent flame resistance without anisotropy, and has excellent appearance and mechanical properties, can be obtained with good moldability. Can be manufactured.

Hereinafter, the present invention will be described in detail.
[Resin composition preparation step]
In the method for producing a polycarbonate resin flame retardant film of the present invention (hereinafter referred to as a flame retardant film), first, a red phosphorus flame retardant stabilized against a polycarbonate resin and a polyfluoroethylene resin are provided. The resin composition preparation process which prepares the resin composition which was mix | blended and further mix | blended the arbitrary component as needed is performed.

The polycarbonate resin used in the present invention is a polymer obtained by a phosgene method in which various dihydroxydiaryl compounds and phosgene are reacted, or a transesterification method in which a dihydroxydiaryl compound and a carbonate such as diphenyl carbonate are reacted.
Examples of the dihydroxydiaryl compound include bisphenol 4-, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2 -Bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxyphenyl-3-methylphenyl) propane, 1,1-bis (4-hydroxy-3- Bis (hydroxyaryl) alkanes such as tert-butylphenyl) propane; Bis (hydroxyaryl) such as 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane ) Cycloalkanes, 4,4'-dihydroxydiphenyl ether, 4,4 Dihydroxy diaryl ethers such as'-dihydroxy-3,3'-dimethyldiphenylether; dihydroxy diaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide Dihydroxydiaryl sulfoxides such as 4,4′-dihydroxydiphenyl sulfoxide, 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfoxide; 4,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxy-3; And dihydroxydiaryl sulfones such as 3,3′-dimethyldiphenyl sulfone and the like, and these may be used alone or in combination of two or more.

  Although there is no restriction | limiting in particular in the viscosity average molecular weight of polycarbonate resin, 10000-100000 are preferable from the point of the moldability and the intensity | strength of the obtained flame-retardant film, More preferably, it is 15000-35000. Moreover, when manufacturing polycarbonate resin, you may add a molecular weight regulator, a catalyst, etc. as needed.

The stabilized red phosphorus flame retardant used in the present invention (hereinafter referred to as stabilized red phosphorus flame retardant) is obtained by subjecting red phosphorus to surface treatment (coating treatment) with various substances. Stabilized red phosphorus flame retardants have the advantages of superior safety and handleability and less odor during molding compared to untreated red phosphorus that has not been surface-treated. For example, the amount of phosphine generated under high temperature and high humidity conditions is small, and the generation of phosphoric acid in high temperature water is also small.
The surface-treated red phosphorus can be used by adjusting the particle size by sieving crushed red phosphorus, which has been known for a long time, or by the spherical shape obtained directly by thermal conversion of yellow phosphorus. Spherical red phosphorus obtained by heat-converting yellow phosphorus from the viewpoint of high stability and high safety during raw material storage and film molding is preferred.

As various treatment substances used for the surface treatment, thermosetting resins, inorganic compounds, and metals can be used.
Examples of the thermosetting resin include phenol resin, phenol-formalin resin, urea resin, urea-formalin resin, melamine resin, melamine-formalin resin, alkyd resin, epoxy resin, and unsaturated polyester resin.
Examples of inorganic compounds include silica, bentonite, zeolite, kaolin, titanium oxide, zinc oxide, magnesium oxide, magnesium carbonate, barium sulfate, calcium phosphate, aluminum hydroxide, magnesium hydroxide, zinc hydroxide, and titanium hydroxide. it can.
As the metal, a metal capable of electroless plating can be used, and examples thereof include iron, nickel, cobalt, copper, zinc, manganese, and aluminum.

  Two or more kinds of treatment substances may be used in combination for the surface treatment. In that case, two or more kinds of treatment substances may be mixed and subjected to a surface treatment all at once, or the surface treatment may be sequentially performed for each treatment substance. Moreover, when surface treatment is performed for each treatment substance, other treatments may be interposed between the surface treatments.

  Specific examples of the surface treatment include a method described in JP-A-7-53779. When the surface treatment is performed with an inorganic compound, for example, red phosphorus particles are suspended in an aqueous solution of a metal water-soluble salt, and a coating layer is formed on the red phosphorus particles by neutralization or metathesis, followed by drying. When surface-treating with a thermosetting resin, the resin raw material or initial condensate is added to the aqueous suspension of red phosphorus particles, and the resulting product is separated, washed, and dried by heating to complete the polymerization reaction. To form a coating layer.

  When the ratio of red phosphorus to the treatment substance during the surface treatment is set so that the content of red phosphorus in the obtained stabilized red phosphorus flame retardant is 20% by mass or more, it is sufficient for a flame retardant film. It is preferable because flame retardancy can be imparted and the cost of the treated substance can be suppressed. Further, when the content of red phosphorus in the obtained stabilized red phosphorus flame retardant is set to be 96% by mass or less, the surface of the red phosphorus particles is sufficiently covered with the treatment substance, and the stability is further improved. Is preferable. The content of red phosphorus in a more preferable stabilized red phosphorus flame retardant is 30 to 96 mass%, more preferably 50 to 95 mass%.

  The stabilized red phosphorus flame retardant preferably has an average particle size of 0.1 to 100 μm, more preferably 0.5 to 30 μm, and even more preferably 1 to 15 μm. Further, those having such an average particle diameter and a particle content of 50 μm or more, more preferably 30 μm or more are preferable. With such a particle size, aggregates are not recognized, whereby a flame retardant film exhibiting excellent appearance and good flame retardancy can be obtained.

  The compounding amount of the stabilized red phosphorus flame retardant is 0.8 to 8 parts by mass, preferably 1 to 8 parts by mass as the amount of red phosphorus (net amount of red phosphorus) with respect to 100 parts by mass of the polycarbonate resin. Preferably it is 1.05-5.5 mass parts. With such a blending amount, high flame retardancy can be imparted to the flame retardant film, and the mechanical properties (for example, bending resistance, etc.) of the flame retardant film are not adversely affected.

Polyfluoroethylene resin is used for the purpose of preventing dripping of combustion products. In the present invention, tetrafluoroethylene-based polymers such as polytetrafluoroethylene and tetrafluoroethylene / propylene copolymers can be preferably used as polyfluoroethylene having fibril-forming ability.
As the form of the polyfluoroethylene resin, fine powder-like fluoropolymer, aqueous dispersion of such fluoropolymer, powder with other resins such as AS (acrylonitrile styrene) resin and PMMA (polymethyl methacrylate resin) Examples thereof include body mixtures, and those in these forms can be used.
Among these, it is preferable to use fine powder-like polytetrafluoroethylene as it is or in the form of an aqueous dispersion because a flame-retardant film having a particularly excellent appearance can be obtained.

The compounding quantity of polyfluoroethylene resin is 0.05-1 mass part with respect to 100 mass parts of polycarbonate resin, Preferably it is 0.1-0.4 mass part. If the amount is less than this, the dripping resistance of the combustion product cannot be obtained. On the other hand, when such a compounding amount is exceeded, periodic thickness variations in the molding direction (flow direction) occur during film molding, and stable molding becomes difficult and molding processability is poor.
In addition, when using a powdery mixture with other resin, such as AS (acrylonitrile styrene) resin and PMMA (polymethyl methacrylate resin), as a polyfluoroethylene resin, the polyfluoroethylene resin in the powdery mixture is used. The quantity of fluoroethylene resin should just be in the said range with respect to 100 mass parts of polycarbonate resins.

As an arbitrary component mix | blended with a resin composition as needed, the inorganic filler which is a component which provides intensity | strength, rigidity, and the more outstanding flame retardance to a flame retardant film is mentioned.
Examples of the inorganic filler include talc, mica, kaolin, diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate, titanium oxide, glass fiber, carbon fiber, and potassium titanate fiber. These inorganic fillers may be surface-treated with a silane coupling agent or a titanate coupling agent. Moreover, 0.5-50 micrometers is preferable and, as for the average particle diameter of an inorganic filler, More preferably, it is 1-20 micrometers.

  The amount of the inorganic filler is not particularly limited, and is determined within the range that does not adversely affect the molding processability, appearance, and mechanical properties of the flame retardant film in consideration of the amount of the stabilized red phosphorus flame retardant. The Specifically, the amount is preferably 0.5 to 20 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the polycarbonate resin.

  Other optional components include antioxidants (phenolic, phosphorus, sulfur), antistatic agents, UV absorbers (benzotriazole, benzophenone), hindered amine light stabilizers, compatibilizers, colorants ( Carbon black, dye, pigment) and the like. The amount of these optional components is appropriately determined within a range that does not adversely affect the flame retardancy of the film.

In the resin composition preparation step, the polycarbonate resin, the stabilized red phosphorus flame retardant, the polyfluoroethylene resin, and optional components blended as necessary may be mixed together, but the polycarbonate resin and the stabilized red After preparing a masterbatch containing a phosphorus flame retardant and a masterbatch containing a polycarbonate resin and a polyfluoroethylene resin, it is preferable to mix these masterbatches. According to such a method, an agglomerate is not recognized, whereby a flame-retardant film that exhibits a more excellent appearance and good flame retardancy can be produced. In particular, by preparing a masterbatch containing a polycarbonate resin and a stabilized red phosphorus flame retardant, safety at the time of raw material storage and film molding is also increased. Moreover, arbitrary components may be mix | blended when mixing these master batches, and may be mix | blended with a master batch.
Each master batch can be prepared by, for example, a method in which each component is melt-mixed with a biaxial kneader in the same direction and formed into a pellet.

[Extrusion process]
Next, an extrusion molding process is performed in which the resin composition prepared in the above-described resin composition preparation process is extruded to form an extruded film (a flame retardant film) having a thickness of 30 to 300 μm.
In the extrusion molding process, a known method such as a T-die extrusion molding method or an inflation extrusion molding method can be adopted. In particular, adjusting the draw ratio at that time to 1.05 to 33 is stable without anisotropy. Important in terms of flame retardancy and moldability. A more preferable draw ratio is 1.1 to 27.
Here, the draw ratio is a ratio A / B between the opening A (μm) of the die lip of the extruder and the thickness B (μm) of the formed film. When the draw ratio is less than 1.05, the molten resin film discharged from the die lip is slackened until it is cooled, the molding processability is poor, and the obtained extruded film loses thickness uniformity. End up. On the other hand, if the draw ratio exceeds 33, stable flame retardancy without anisotropy cannot be obtained. Specifically, when the flame-retardant film is formed in the length direction of the specimen of the thin material vertical combustion test according to the UL94 standard, the shrinkage (shrinkage) of the film increases during flame contact, and the residual flame is the standard. May reach the line.

  Moreover, the cylinder temperature in an extrusion molding process is adjusted in the range of 260-330 degreeC, and it adjusts suitably, seeing the thickness uniformity and external appearance of a film.

Since the flame-retardant film thus manufactured has a thickness of 30 to 300 μm, the flame-retardant film is used as an OA device, an information / communication device, an electric / electronic device having a casing made of polycarbonate resin, for example. When used as a film substrate for films affixed to devices such as devices, household appliances, and lithium-ion secondary batteries, these devices will be adversely affected by the lighter, smaller, thinner, and casing recycling. There is nothing.
In general, a thin film is difficult to maintain a good appearance due to the effects of additives and the like, and tends to be difficult to form a film. Although it is as thin as 30 to 300 μm, the blending amount of the stabilized red phosphorus flame retardant and the polyfluoroethylene resin is appropriately controlled, and the draw ratio in the extrusion process is controlled to a specific range, so that the appearance is good. Further, it is possible to maintain moldability, mechanical properties, and high flame retardancy without anisotropy.
As flame retardancy, specifically, in a thin material vertical combustion test according to the UL94 standard, a level conforming to VTM-0 can be achieved regardless of the cutting direction of the test piece.

As described above, the method for producing a polycarbonate resin flame-retardant film according to the present invention includes a resin composition preparation step for preparing a resin composition, and extrusion molding the resin composition to have a thickness of 30 to 300 μm. An extrusion molding step of molding an extruded film, and 0.8 to 8 parts by mass of red phosphorus flame retardant stabilized as an amount of red phosphorus is blended with respect to 100 parts by mass of the polycarbonate resin. Since the ethylene resin is blended in an amount of 0.05 to 1 part by mass and the draw ratio in the extrusion molding process is 1.05 to 33, the flame retardant stably has no anisotropy, A polycarbonate resin flame retardant film having a thickness of 30 to 300 μm and excellent in appearance and mechanical properties can be produced with good moldability.
Further, in the resin composition preparation step, after preparing a masterbatch containing a polycarbonate resin and a stabilized red phosphorus flame retardant and a masterbatch containing a polycarbonate resin and a polyfluoroethylene resin, respectively, these masterbatches By mixing these, no agglomerates are observed, whereby a flame retardant film exhibiting a more excellent appearance and good flame retardancy can be produced.

Hereinafter, the present invention will be specifically described with reference to examples.
[Material of flame retardant film]
Component A1: “Polycarbonate resin”: manufactured by Sumitomo Dow, Gulliver 200-3, bisphenol A-type polycarbonate, viscosity average molecular weight = 28000
Component A2: “Polycarbonate resin”: manufactured by Sumitomo Dow, Gulliver 200-13, bisphenol A type polycarbonate, viscosity average molecular weight = 21000
Component B: “Stabilized Red Phosphorus (Stabilized Red Phosphorus Flame Retardant)”: manufactured by Phosphor Chemical Co., Ltd., Nova Excel 140F, spherical red phosphorus particles obtained by thermal conversion of yellow phosphorus into inorganic compounds (aluminum hydroxide) ) And a thermosetting resin (thermosetting phenol resin), average particle diameter = 10 μm, red phosphorus content = 91 mass%
Component BM: “Stabilized red phosphorus flame retardant masterbatch”: Pellets obtained by melt-mixing component A2 and component B with a biaxial kneader in the same direction to a mass ratio of 85/15 Component C: “ “Polytetrafluoroethylene”: manufactured by Daikin Industries, Ltd., Polyflon MPA FA500C, fine powder Component CM: “Polytetrafluoroethylene masterbatch”: biaxial in the same direction so that component A2 and component C have a mass ratio of 100 / 2.5 Pellets obtained by melting and mixing with a kneader Component D: “talc”: talc P-4 manufactured by Nippon Talc Co., Ltd. was surface treated with 3-glycidoxypropyltrimethoxysilane KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd. Average particle size 4.3 μm
Ingredient E: “Carbon black”: manufactured by Tokai Carbon Co., Ltd.

[Examples and Comparative Examples]
(1) Production of Flame Retardant Film The above components are blended in the blending amounts (parts by mass) shown in Tables 2 and 3 and mixed uniformly with a Henschel mixer, and the prepared resin composition is biaxial with a 37 mm diameter in the same direction. It supplied to the extruder (L / D = 42). Melting and kneading at a cylinder temperature of 280 ° C., discharging a molten resin from a T-die, cooling it while taking it with a pinch roll set at 130 ° C., and having a thickness shown in Tables 2 and 3, a flame resistance of 500 mm in width A film was produced.
In addition, the opening degree of the T die lip of the extruder was adjusted so that the draw ratio in each example was a value shown in the table.
(2) Evaluation (i) Evaluation of film appearance (smoothness) and molding processability (thickness uniformity) The film smoothness of each flame-retardant film was visually evaluated.
The moldability of each flame retardant film was evaluated by the uniformity of the film thickness. Specifically, along the film forming direction, the thickness was measured at 50 points at intervals of 50 mm with a micrometer, and thickness variation = (maximum value−minimum value) / average value was determined and evaluated.
“◯”: Excellent film smoothness and thickness variation = 0.1 or less.
“X”: Other than the above “◯”.
(Ii) Bending resistance (mechanical properties)
The extrusion-molded flame-retardant film was measured in accordance with JIS P8115, and the number of reciprocal bendings until the test piece was broken with an MIT tester was measured. When the number of reciprocal bendings was 30 times or more, “◯” was indicated, and when the number of reciprocal bendings was less than 30, “X” was indicated.
The test piece was 15 mm wide × 150 mm long, and the film forming direction was the length direction of the test piece.
MIT test conditions were: bending clamp tip radius 0.38 mm, folding clamp opening clearance 1.0 mm, spring load 9.8 N, bending angle (one side) 135 °, reciprocating bending speed 175 times / minute, measurement environment 23 ° C. 50% RH.
In general, the number of reciprocal folding depends on the thickness of the same film, and the number of times increases as the thickness decreases. When the number of reciprocal bendings is 30 times or more, cracks and cracks are unlikely to occur when the film is processed (bending, slitting, punching, etc.).
(Iii) Flame retardancy Two types of test pieces (width 50 mm × length 200 mm) with different cutting directions were cut out from each flame retardant film produced in (1) above. That is, what was cut out so that the length direction of the test piece and the molding direction (flow direction) of the flame-retardant film coincided with each other is referred to as “vertical” in the table, and the width direction and the molding direction of the flame-retardant film (flow direction) ) Were cut out so as to coincide with each other and designated as “horizontal” in the table.
These test pieces were stored in an environment of 25 ° C. and 50% RH for 168 hours, and then a thin material vertical combustion test (VTM test) according to the UL94 standard was performed.
A VTM test was also conducted on a test piece dried in a gear oven at 70 ° C. for 168 hours.
In each evaluation, five test pieces were used.
In addition, the flame contact time was 3 seconds, the flame was contacted twice with respect to one test piece, and the afterflame time after the flame contact was measured. Further, the marked line is located at a position 125 mm from the lower end of the test piece, and the marking cotton is disposed 300 mm below the lower end of the test piece.
Table 1 shows the VTM test class criteria.
In Tables 2-3, the evaluation result of each Example and a comparative example is shown.

  In the table, the maximum burning time is the maximum value among t1 and t2 for five test pieces. The total burning time is the sum of all t1 and t2 of the five test pieces. Further, in this example, whether the melt of the test piece falls or whether the non-molten product falls is determined as “dripping”.

According to each Example, it was possible to produce an extruded film having a thickness of 30 to 300 μm that stably had excellent flame retardancy without anisotropy and had excellent appearance.
On the other hand, in Comparative Example 1 with a small amount of red phosphorus flame retardant, the flame retardancy was insufficient, and in Comparative Example 2 with a large amount of red phosphorus flame retardant, the bending resistance was inferior. In Comparative Example 3 with a small amount of polyfluoroethylene, in particular, the combusted material was dripped, and the flame retardancy was insufficient in that respect. In Comparative Example 4 having a large amount of polyfluoroethylene, an attempt was made to form a film having a thickness of 30 to 300 μm, but the thickness variation was large, and the film formation itself was impossible. In Comparative Example 5 having a large draw ratio, when the test piece was “horizontal”, good flame retardancy was obtained, but in the case of “vertical”, the film contracted during flame contact. As a result, the flame retardancy was insufficient. That is, in Comparative Example 5, flame retardancy anisotropy was significant.

Claims (2)

A resin composition preparation step for preparing a resin composition in which a polycarbonate resin, a stabilized red phosphorus flame retardant, and polyfluoroethylene are blended, and the resin composition is extruded to have a thickness of 30 An extrusion process for forming an extruded film of ˜300 μm,
With respect to 100 parts by mass of the polycarbonate resin, the stabilized red phosphorus flame retardant is blended in an amount of 0.8 to 8 parts by mass as red phosphorus, and the polyfluoroethylene resin is blended in an amount of 0.05 to 1 part by mass. And
The method for producing a polycarbonate resin flame-retardant film, wherein a draw ratio in the extrusion molding step is 1.05 to 33.   In the resin composition preparation step, after preparing a masterbatch containing a polycarbonate resin and a stabilized red phosphorus flame retardant, and a masterbatch containing a polycarbonate resin and a polyfluoroethylene resin, respectively, The method for producing a flame-retardant polycarbonate resin film according to claim 1, wherein a masterbatch is mixed.