JP2016079231A - White flame-retardant polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white flame-retardant polyester film which exhibits excellent flame retardancy even if containing a white pigment and having a large number of voids (gaps), for example, to provide a film which can be suitably used in applications for a battery label or a flat cable of a personal computer or a portable telephone, a lighting component material, a wiring component material of a collector electrode called bus bar or the like.SOLUTION: There is provided a white flame-retardant polyester film which comprises a phosphorus-based flame retardant compound and a white pigment, wherein the ratio (the void occupancy/the content of the phosphorus element) of the void occupancy to the content of the phosphorus element is 20.0 or less.SELECTED DRAWING: None

Description

  The present invention relates to a white flame retardant polyester film. More specifically, the present invention relates to a white flame retardant polyester film that exhibits excellent flame retardancy even when it contains a white pigment and has many voids (voids).

  Various white polyester films have been proposed so far, and they are widely used in various applications such as labels and posters, solar battery backsheet films, display reflectors, and window pastes due to their excellent reflectivity and concealment. (Patent Document 1).

  Due to the recent increase in heat generation due to the downsizing and higher efficiency of personal computers and mobile phones, the polyester film used around electrical components such as labels and displays, lighting, and printers used in the batteries of these devices is derived from heat generation. There is an increasing demand for flame retardancy from the viewpoint of fire prevention.

  As a flame retardant compound capable of imparting flame retardancy to a polyester film, halogen-containing compounds such as organic halogen compounds and halogen-containing organic phosphorus compounds are known to have a high flame retardant effect. However, a resin containing a halogen-containing flame retardant compound has been regarded as a problem that a toxic gas is generated during processing or combustion. In particular, it has been pointed out that bromine-containing flame-retardant compounds generate hydrogen bromide gas during molding and processing, and generate dioxin-like gas during combustion. Therefore, in recent years, it has been strongly demanded to use a flame retardant compound containing no halogen.

  In addition, as other flame retardant compounds, inorganic compounds typified by magnesium hydroxide, inorganic phosphorus compounds typified by red phosphorus, and organic phosphorus compounds such as phosphate esters, phosphonic acid compounds and phosphinic acid compounds are known. .

  Patent Document 2 is an invention in which a white polyester film is made flame retardant. However, since a white film has many voids (voids), it is difficult to make flame retardant compared to a transparent polyester film. It cannot be said that the invention has been made.

JP-A-9-165501 JP 2014-84383 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is a white flame-retardant polyester film that exhibits excellent flame retardancy even if it contains a white pigment and has many voids (voids). An object of the present invention is to provide a film that can be suitably used for, for example, a battery label of a personal computer or a mobile phone, a flat cable, a lighting component material, and a wiring component material of a collecting electrode called a bus bar.

  As a result of intensive investigations in view of the above problems, the present inventors have added white phosphorus flame retardant polyester having excellent characteristics by adding a phosphorus element content at a certain ratio to the void occupancy in the film. It has been found that a film can be obtained, and the present invention has been completed.

  That is, the gist of the present invention includes a phosphorus-based flame retardant compound and a white pigment, and a ratio between the void occupation ratio (%) and the phosphorus element content (wt%) (void occupation ratio / phosphorus element content). Is a white flame retardant polyester film, characterized in that it is 20.0 or less.

  ADVANTAGE OF THE INVENTION According to this invention, the white flame-retardant polyester film which shows the outstanding flame retardance can be provided even if it has many voids (space | gap) including a white pigment. The film can be suitably used for battery labels of personal computers and mobile phones, flat cables, lighting component materials, wiring component materials for collecting electrodes called bus bars, and the industrial value of the present invention is high.

The resin used in the polyester film of the present invention is not particularly limited, and is mainly a polyester obtained using aromatic dicarboxylic acid or its ester and glycol as main starting materials, and has 60 repeating structural units. % Or more refers to a polyester having ethylene terephthalate units or ethylene-2,6-naphthalate units. And if it is the conditions which do not deviate from said range, the other 3rd component may be contained.
For example, a mixture of a resin compatible with a polyester-based resin such as polycarbonate can be used.

  Examples of the aromatic dicarboxylic acid component include terephthalic acid, dimethyl terephthalate, and 2,6-naphthalenedicarboxylic acid, for example, isophthalic acid, phthalic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxyethoxy) Benzoic acid etc.) can be used. In particular, terephthalic acid or dimethyl terephthalate is preferably used.

  As an example of a glycol component, 1 type, or 2 or more types, such as diethylene glycol, propylene glycol, butylene glycol, can be used other than ethylene glycol, for example. In particular, it is preferable to use ethylene glycol.

  The polyester film as referred to in the present invention refers to a film which is extruded by a co-extrusion method in which all layers are co-melt extruded from a die and then heat-set as necessary. In the present invention, the polyester film may be a single layer, two layers, or a multilayer of three or more layers as long as the purpose is satisfied.

  The phosphorus element content (% by weight) in the white flame-retardant polyester film of the present invention is determined by ICP described later. The range of the phosphorus element content of the white flame retardant polyester film is usually 0.21 to 1.50% by weight, preferably 0.30 to 1.40% by weight, and 0.40 to 1.30% by weight. More preferred is 0.50 to 1.20% by weight. When the phosphorus element content is less than 0.21% by weight, the flame retardancy tends to be unstable. Further, when the phosphorus element content is higher than 1.50% by weight, breakage in the tenter may occur frequently.

  Specific examples of phosphorus-based flame retardant compounds used in the present invention include aromatic phosphate esters, alkyl phosphate esters, acidic phosphate esters, polyphosphonitriles, nitrogen-containing phosphorus compounds, polymerizable phosphorus compound monomers, phosphones. Organic phosphorus compounds such as acid compounds, phosphinic acid compounds, phosphine oxide compounds, and phosphaphenanthrene compounds, inorganic phosphorus compounds, and the like can be given.

  In this invention, it is more preferable to use what is shown by following Chemical formula (1) among the above-mentioned phosphorus flame retardant compounds. If the phosphorus-based flame retardant compound represented by the chemical formula (1) is used, the film has flame retardant properties while maintaining mechanical properties, thermal properties such as heat resistance and heat shrinkage, and electrical properties such as dielectric breakdown voltage. Can be granted. A polyester compound copolymerized with a phosphorus compound has a structure in which a phosphorus compound having a lower softening point intervenes, and the melting point is lowered. Therefore, mechanical properties, thermal properties such as heat resistance and heat shrinkage, insulation It is conceivable that electrical properties such as breakdown voltage are deteriorated. In particular, in the case of phosphate esters, the bond energy of PO in the compound is low, and the ester group cleavage and molecular weight reduction in the polyester are caused by the autocatalytic action accompanying the main chain cleavage during molding and processing. It also has the disadvantage of happening. That is, in order to exhibit higher flame retardancy, the mechanical properties and thermal properties are worsened as the amount of copolymerization of the phosphorus compound in the polyester is increased.

  The organophosphorus compound represented by the chemical formula (1) contains a phosphorus atom in the molecule, and the lower limit of the repeating unit of n is 4, preferably 8, and more preferably 12. If the repeating unit is less than 4, the mechanical strength may be reduced due to volatilization of the organophosphorus compound during film formation and inhibition of crystallization of the polyester resin. Furthermore, due to bleeding out of the organic phosphorus compound, a sticky component is generated on the surface of the polyester pellet, which is not preferable from the viewpoint of adhesion. On the other hand, the upper limit of the repeating unit of n is not particularly defined, but it is considered that dispersibility of the flame retardant compound (1) in the resin is inhibited by excessively increasing the molecular weight. In addition, the synthesis method (production example) of the flame retardant compound (1) will be described later.

  In the present invention, in order to contain the flame retardant compound in the polyester film, the flame retardant compound was previously kneaded into a masterbatch by using a technique for directly adding the flame retardant compound or an extruder during the production of the polyester film. There is a way to use things. Moreover, when manufacturing a flame-retardant polyester film, it does not specifically limit about the method of adding the said flame-retardant compound directly.

  The content of the white pigment contained in the film of the present invention is preferably in the range of 2.0 to 20.0% by weight, more preferably in the range of 4.0 to 18.0% by weight, and 6.0 to 15. A range of 0% by weight is particularly preferred. When the content of the white pigment is less than 2.0% by weight, the film may not be sufficiently colored or concealed, resulting in poor appearance. On the other hand, when the white pigment content is 20.1% or more, the concealing property is saturated, which may not be preferable in terms of cost.

  Examples of the white pigment used in the present invention include titanium dioxide and barium sulfate. At least one selected from these is used. When titanium dioxide is used, either a rutile type or an anatase type may be used. Further, the white pigment may be in the form of a porous or hollow porous material, and further, a white pigment that has been subjected to a surface treatment for improving dispersibility in the resin may be used.

  The white flame-retardant polyester film of the present invention usually contains at least one element of Ti, Ba and Ca, and the content range is preferably 0.1 to 15.0%, 0.5-12.5% is more preferable, 1.0-10.0% is further more preferable, and 2.0-9.0% is the most preferable.

  The film thickness of this invention is 100 micrometers or more normally, More preferably, it is 125 micrometers or more. When the thickness of the film is less than 100 μm, the concealability is not sufficient and the appearance may be poor. Even if the film thickness is less than 100 μm, if a large amount of white pigment is added, the concealability can be improved. However, a large amount of phosphorus element is required to make it flame retardant, which is preferable in terms of cost. There may not be.

  In white polyester film containing white pigment, when biaxially stretched, many voids called voids are created around the white pigment, and the specific surface area in contact with air that promotes combustion increases, so there is no void. Flame retardancy is difficult compared to film. In addition, void formation tends to increase as the content of the white pigment in the film increases, and it is more difficult to make a white film having higher concealability flame-retardant.

  The void occupancy (%) in the present invention refers to the area ratio of the white pigment and voids formed around it in the film cross section.

  In the present invention, the ratio of void occupancy to phosphorus element (void occupancy / phosphorus element content) is 20.0 or less, preferably 18.0 or less, more preferably 16.0 or less, Preferably it is 14.0 or less. A film having a void occupancy ratio / phosphorus element content exceeding 20.0 has voids that exceed the range in which the phosphorus element is made flame-retardant, and cannot exhibit flame retardancy.

  In addition to the method of controlling the void occupancy and the ratio of phosphorus element as described above, the method of controlling the heat shrinkage rate to be low is also very effective in making the white polyester film containing the white pigment flame retardant. Is. If the white polyester film is made to have a low shrinkage rate, the void volume created by biaxial stretching can be made physically smaller, making it difficult to burn.

  The white flame-retardant polyester film of the present invention has a heat shrinkage rate of 190% at 5 ° C. in the machine direction (MD) and the transverse direction (TD), usually 3.0% or less, preferably 2.5% or less. More preferably, it is 2.0% or less, and most preferably 1.5% or less. A film having a thermal shrinkage rate of more than 3.0% at 190 ° C. for 5 minutes in the machine direction (MD) and the transverse direction (TD) has a large void volume derived from the white pigment, resulting in a large specific surface area in contact with air. Therefore, there is a tendency that it takes time to extinguish the flame.

  The intrinsic viscosity of the film of the present invention is preferably 0.45 dl / g or more, more preferably 0.47 dl / g or more, further preferably 0.49 dl / g or more, particularly preferably 0.51 dl / g or more, and Most preferred is 53 dl / g or more. If the intrinsic viscosity of the film is less than 0.45 dl / g, the film tends to break during film formation.

  The upper limit of the intrinsic viscosity of the white flame retardant polyester film is not particularly set, but is preferably 1.0 dl / g, more preferably 0.9 dl / g, further preferably 0.8 dl / g wt%, and 0.75 dl / g. Is particularly preferred. When the intrinsic viscosity of the white flame-retardant polyester film is higher than 1.0 dl / g, the load in the extrusion process during the production of the polyester film tends to be too large, and the productivity may be lowered.

  The white flame-retardant polyester film in the present invention has a lubricant, an antistatic agent, an antioxidant, an ultraviolet absorber, an antifogging agent, a cross-linking agent, a plasticizer, an antiblocking agent, and a polyester as long as the properties are not affected. You may make it contain the collection | recovery composition of a resin, and the collection | recovery composition of a flame-retardant polyester-type resin.

  The flame-retardant polyester film of the present invention is preferably one in which all the layers are stretched biaxially and heat-set by a co-extrusion method in which all layers are co-melt extruded from a die. As a method for co-melt extrusion, either a feed block type or a multi-manifold type may be used. Then, although the manufacturing method of the polyester film of this invention is demonstrated more concretely, as long as the structural requirements of this invention are satisfied, it is not specifically limited to the following illustrations.

  First, a polyester raw material containing a flame retardant compound and, if necessary, inert particles is supplied to an extruder, heated to a temperature equal to or higher than the melting point of the polymer, and melted. Next, the molten polymer is extruded from a T-die and rapidly cooled and solidified on a rotating cooling drum so as to be a temperature not higher than the glass transition temperature, thereby obtaining a substantially amorphous unoriented sheet. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum. In the present invention, an electrostatic application adhesion method and / or a liquid application adhesion method is employed.

  In the present invention, the sheet obtained by such a method is stretched in the biaxial direction. Specifically describing the stretching conditions, the unstretched sheet is stretched 2 to 6 times in the machine direction (MD) at 70 to 145 ° C. to form a longitudinal uniaxially stretched film, and then in the transverse direction (TD) 90 to 160 ° C. It is preferable that the film is stretched 2 to 6 times and heat-treated at 200 to 250 ° C. for 1 to 600 seconds. Further, in order to adjust the heat shrinkage rate, it is possible to relax in the longitudinal direction and / or the transverse direction in the maximum temperature zone of the heat treatment and / or the cooling zone at the heat treatment outlet, and to provide re-stretching or the like.

  Further, the white flame-retardant polyester film of the present invention may be provided with functional layers such as ink easy adhesion, antistatic, adhesive easy adhesion, oligomer sealing, mold release, and anti-blocking unless the flame retardancy is lowered. . The functional layer is provided by in-line coating or off-line coating at the time of forming a polyester film, but it is more preferable to carry out by in-line coating from the viewpoint of cost.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The physical property measurement method used in the present invention is shown below.

(1) Film thickness (μm)
Measured with a micrometer.

(2) Intrinsic viscosity (dl / g)
A polyester sample of 0.5 g was dissolved in a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio), and the flow time of a solution having a concentration of 1.0 (g / dl) was measured using a capillary viscometer, In addition, the flow-down time of only the solvent was measured, and the intrinsic viscosity was calculated from the time ratio using the Huggins formula. At that time, the Huggins constant was assumed to be 0.33.

(3) Phosphorus element content (%)
ICP: Varian Tech. The phosphorus element content (%) in the polyester sample was determined by acid decomposition with nitric acid using ICP-AES manufactured by the company.

(4) White pigment content (%)
It calculated | required with the following formula | equation.
White pigment content (%) = 50 × I ÷ 100
(In the above formula, I represents the weight ratio (%) of the polyester raw material (4) described later blended in the film)

(5) Content of each element type [%]
XRF: The amount of elements in the film was determined by single-sheet measurement under the conditions shown in Table 1 below using a fluorescent X-ray analyzer (model “XRF-1800” manufactured by Shimadzu Corporation).

(6) Void occupation rate (%)
Using a microtome, the film was cut in the transverse direction (TD) to obtain a section for cross-sectional observation. Next, the cross section of the film was magnified 5000 times using a scanning electron microscope S-3400N (manufactured by Hitachi, Ltd.) to obtain a cross-sectional photograph. The obtained cross-sectional photograph was binarized as a void portion (white pigment and void) and other portions using image analysis software WinROOF V07. The total area subjected to the binarization process was A (1280 × 890 pixels), the area of the void portion was B (pixel), and the void occupation rate was obtained using the following equation.
Void occupation ratio (%) = B ÷ A × 100

(7) Void Occupancy / Phosphorus Element Content Using the measured values obtained from the above (3) phosphorus element content (%) and (6) void occupancy (%), the following formula was used.

  Void Occupancy / Phosphorus Element Content = Void Occupancy (%) ÷ Phosphorus Element Content (%)

(8) Thermal shrinkage (%) at 190 ° C. for 5 minutes
The film in a tensionless state is heat-treated in an atmosphere of 190 ° C. for 5 minutes, and the length of the film before and after the heat treatment in the machine direction (MD) and the transverse direction (TD) is measured. It represented with the average value about the sample of this.
Thermal contraction rate (%) = (L ₀ −L ₁ ) × 100 / L ₀
(In the above formula, L ₀ represents the sample length (mm) before heat treatment, and L ₁ represents the sample length (mm) after heat treatment)
Nao, L ₀ may be less than L ₁ (when the film expands) the value I of the heat shrinkage - expressed in (negative).

(9) Transmission Density A Macbeth densitometer TD-904 type was used to measure the transmission density under the G filter. The larger this value, the higher the hiding power.

(10) Flame retardancy 8-1 Preparation of test piece As a film test piece, cut into 200 mm x 50 mm, and put a marked line across the width of the sample at 125 mm from one end (lower part) of the sample. The sample longitudinal axis is tightly wound around the mandrel with a diameter of 12.7 mm so that a 125 mm line is exposed to the outside and becomes a rolled cylinder with a length of 200 mm. The edge that protrudes outside the sample is fixed with an adhesive tape between 75 mm above the 125 mm mark (upper part of the cylinder). Then pull out the mandrel.

8-2 Conditioning The test piece obtained above is aged at 70 ° C. for 168 hours, and then pretreated at 23 ° C. and 50% relative humidity for 48 hours.

8-3 Combustion test procedure 8-3-1 Specimen fixation The vertical axis of the sample is fixed vertically with a clamp with a strong spring at a position of 6 mm in the upper end, and the upper end of the cylinder is closed during the test. Avoid the chimney effect. The lower end of the sample should be 300 mm above one horizontal 0.05 g defatted 100% cotton (50 mm × 50 mm) with a maximum thickness of 6 mm.

8-3-2 Adjusting the burner Adjust the burner so that a blue flame with a height of 20 mm appears from the burner. In order to put out the flame, the gas supply and the air inlet of the burner are adjusted so that the yellow flame with a yellow tip of 20 mm comes out. Then increase the air supply until the yellow tip just disappears. Measure the flame height again and readjust as necessary. In addition, the methane gas supply to a burner adjusts a flow volume by the method according to ASTMD5207.

8-3-3 Flame contact for the first time The flame is centered on the center point of the lower end of the sample, and the tip of the burner is 10 mm below that point at the lower end of the sample. Continue for 3 seconds at a distance. However, the burner is moved in response to any change in the length or position of the sample. If a molten or fuming substance drips during flame contact, tilt the burner angle up to 45 degrees, just below the sample to prevent the substance from falling into the burner tube. Move from. However, the interval between the center of the tip of the burner and the remaining portion of the sample must be kept 10 mm ± 1 mm during that time. When the sample has an indirect flame for 3 seconds, the burner is immediately moved away from the sample at a rate of about 300 mm at a rate of at least 150 mm per second, and at the same time, the after flame time t ₁ is started to be measured in seconds by the timing device. And it records the _{t 1.}

8-4-4 Second flame contact When the after flame of the sample is extinguished (even if the burner is not completely removed to a distance of 150 mm from the sample), immediately bring the burner under the sample. Then, a burner is held at a location 10 mm ± 1 mm away from the rest of the sample. However, if necessary, move the burner so that the natural behavior of the fallen object can be confirmed without any obstructions. After this sample 3 seconds flame application, immediately away at least 150mm at a speed of about 300 mm, starts weighing the remaining flame time t ₂ seconds by a timing device at the same time.

8-5 Flame Retardancy Evaluation Criteria The test is performed on the five test pieces according to the procedure described in Section 4-3 above. Judgment evaluation was performed based on the following three rank criteria from the total time of five afterflame times (t ₁ + t ₂ ).
◎: The total time of 5 after flame times (t ₁ + t ₂ ) is less than 20 seconds. ○: The total time of 5 after flame times (t ₁ + t ₂ ) is 21 to 40 seconds. there △: five total time of the remaining flame time _{(t 1} + _{t 2)} is, × is 41-60 seconds: five total time of the remaining flame time _{(t 1} + _{t 2)} is more than 61 seconds Is

(11) Concealment property Using a transparent double-sided adhesive tape, the film was attached to paper on which red, blue, and black letters were written, and visual evaluation was performed from the film side.
○: Characters written on paper are completely invisible △: Characters written on paper are slightly visible

(12) Film-forming properties Assuming continuous production, from the frequency of product breakage, from the production of an unstretched sheet to the longitudinal stretching and transverse stretching of the unstretched sheet and winding up as a roll, the following three rank criteria Judgment was evaluated.
A: The frequency of one film break is 30 minutes or more. ○: A film break occurs once in 10 minutes or more but less than 30 minutes. Δ: A film break occurs once or more in less than 10 minutes.

  The flame retardant compounds used in the following examples and comparative examples, and the method for producing the polyester raw material are as follows. Unless otherwise specified, “parts” in the examples and comparative examples are “parts by weight”, “ “%” Means “% by weight”.

<< Flame-retardant compound (1): Organophosphorus compound (Chemical formula (1)) >>
9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (the following chemical formula (2)) 7 was added to a 3 L glass flask equipped with a stirrer, thermometer, gas inlet, and distillation port. .8 mol and ethylene glycol 25.97 mol were added, and the flask was heated until the temperature of the contents reached 100 ° C. in order to dissolve the components. Next, 7.96 mol of itaconic acid was added with stirring, and the flask was heated from the distillation port through a vacuum device in a vacuum state of 30 Torr to bring the contents to a boil. At this point, the produced water was removed by adjusting the distillation rate of the distillation port. Furthermore, while maintaining the boiling state of the contents, the temperature in the flask was raised, and the degree of vacuum was also lowered accordingly. As a breakdown, it took 4 hours for the temperature of the contents to reach 185 ° C., and the degree of vacuum at this point was 430 Torr. Further, the heating was continued, and finally the contents were heated until the temperature reached 200 ° C. After confirming this point, nitrogen gas was blown into the reactor to return the flask to normal pressure. The reaction mixture is an ethylene glycol solution of the following chemical formula (3). Moreover, the solid compound of the following chemical formula (3) can be purified by removing ethylene glycol under reduced pressure.

Subsequently, 130 g of ethylene glycol containing 0.33 g of antimony trioxide (Sb ₂ O ₃ ) and zinc acetate dihydrate [(AcO) ₂ Zn · 2H ₂ O] was added into the flask. The inside of the flask was maintained at 200 ° C., and the degree of vacuum was gradually increased to obtain a vacuum state of 1 Torr or less. Furthermore, the temperature of the content was raised to 220 ° C., and the point at which the distillation of ethylene glycol was extremely reduced was determined as the reaction end point. After confirming this point, the flame retardant compound (1), which is a yellowish transparent glassy solid, was obtained by solidifying the contents in a SUS container while pressurizing the contents with nitrogen gas.

  By repeating the above operation, the necessary amount of the flame retardant compound (1) to be added in Examples and Comparative Examples described later was secured.

  As for this flame retardant compound (1), the weight average molecular weight (Mw) was 6,800 from GPC analysis of the product. In the analysis, a peak in a low molecular weight region, which was estimated to be an acid anhydride of a compound represented by the following chemical formula (4) or a cyclic ester of compound (4) and ethylene glycol, was also observed. Therefore, it can be said that the average value of n of the flame retardant compound (1) corresponds to 18.1. ICP measurement showed that the phosphorus element content (% by weight) was 8.01.

≪Manufacture of polyester raw material A≫
100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol are used as starting materials, 0.02 part of magnesium acetate tetrahydrate is taken as a catalyst in the reactor, the reaction start temperature is 150 ° C., and the methanol is gradually distilled off. The reaction temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.03 part of ethyl acid phosphate to this reaction mixture, it moved to the polycondensation tank, added 0.04 part of antimony trioxide, and performed polycondensation reaction for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, the reaction was stopped when the intrinsic viscosity (dl / g) was 0.64 due to the change in the stirring power of the reaction vessel, the polymer was discharged under nitrogen pressure, extracted into a strand shape, The polyester raw material A was manufactured by cutting with a cutter. The intrinsic viscosity (dl / g) was 0.64.

≪Production of polyester raw material (1) ≫
Polyester raw material A was used as a starting raw material, and solid phase polymerization was performed at 220 ° C. under vacuum to obtain a polyester raw material (1) in a pellet state. The intrinsic viscosity (dl / g) of the obtained polyester was 0.85.

≪Manufacture of polyester raw material (2) ≫
Polyester obtained by washing and drying a recyclable polyethylene terephthalate bottle, crushing it, and re-pelleting it through a remelting process is polymerized by solid phase polymerization at 220 ° C under vacuum to obtain a pelletized polyester raw material (2) It was. The intrinsic viscosity (dl / g) of the obtained polyester was 1.10.

≪Production of polyester raw material (3) ≫
A flame retardant resin obtained by kneading and extruding 35% by weight of the flame retardant compound (1) and 65% by weight of the polyester raw material (1) produced by the above method with a twin-screw kneader with a vent set to 290 ° C. A pellet of the composition was obtained. The intrinsic viscosity (dl / g) of the obtained polyester raw material (3) was 0.45.

≪Manufacture of polyester raw material (4) ≫
50 parts by weight of the polyester raw material (1) and 50 parts by weight of anatase-type titanium dioxide particles having an average particle size of 0.3 μm were mixed and melt-extruded with a vented twin-screw extruder to obtain a polyester raw material (4). The intrinsic viscosity was 0.33 (dl / g).

Example 1:
The polyester raw material (1), the polyester raw material (3) and the polyester raw material (4) mixed at a ratio of 76.3: 10.7: 13.0 were mixed with a twin screw extruder with a vent of 90 mm in diameter. Discharge rate: 500 kg / hr, cylinder temperature; melt extrusion at 280 ° C., and amorphous polyester sheet flowing out from the die is rapidly cooled and solidified on a casting drum set at a surface temperature of 40 ° C. using an electrostatic application adhesion method An unstretched single layer sheet was obtained. Next, the film was stretched 3.0 times in the machine direction at a film temperature of 85 ° C. using the roll peripheral speed difference, and then led to a tenter, and the longitudinally stretched sheet held by a clip was stretched 4.0 times at 125 ° C. in the transverse direction. Then, heat treatment was performed at 235 ° C., and the film was relaxed by 3.0% in the transverse direction in the cooling zone at the heat treatment outlet to obtain a polyester film having a thickness of 188 μm. The characteristics of the polyester film are shown in Table 2 below.

Example 2:
Example 1 except that the polyester raw material (1), the polyester raw material (3), and the polyester raw material (4) were mixed at a ratio of 84.3: 10.7: 5.0 and the thickness was 175 μm. A polyester film was obtained by the same method. The properties of the obtained film are shown in Table 2.

Example 3:
Example 1 except that the polyester raw material (1), the polyester raw material (3), and the polyester raw material (4) were mixed at a ratio of 72.3: 10.7: 17.0, and the thickness was 150 μm. A polyester film was obtained by the same method. The properties of the obtained film are shown in Table 2.

Example 4:
The heat treatment temperature was 210 ° C. and 0.0% using the polyester raw material in which the polyester raw material (1), the polyester raw material (3) and the polyester raw material (4) were mixed at a ratio of 65.5: 21.5: 13.0. A polyester film was obtained by the same method as in Example 1 except that the thickness was 175 μm. The properties of the obtained film are shown in Table 2.

Example 5:
A polyester raw material in which the polyester raw material (2), the polyester raw material (3) and the polyester raw material (4) were mixed at a ratio of 46.8: 32.2: 21.0 was used, and the heat treatment temperature was 225 ° C. and the thickness was 125 μm. Except for the above, a polyester film was obtained in the same manner as in Example 1. The properties of the obtained film are shown in Table 2.

Example 6:
Example except that polyester raw material (2), polyester raw material (3) and polyester raw material (4) were mixed at a ratio of 35.4: 28.6: 36.0 and the heat treatment temperature was 220 ° C. A polyester film was obtained in the same manner as in 1. The properties of the obtained film are shown in Table 2.

Example 7:
Example except that polyester raw material (2), polyester raw material (3) and polyester raw material (4) were mixed at a ratio of 36.1: 42.9: 21.0, and the heat treatment temperature was 220 ° C. A polyester film was obtained in the same manner as in 1. The properties of the obtained film are shown in Table 2.

Example 8:
A polyester film was obtained in the same manner as in Example 1 except that the heat treatment temperature was 205 ° C. The properties of the obtained film are shown in Table 3.

Example 9:
A polyester film was obtained in the same manner as in Example 1 except that the heat treatment temperature was 215 ° C. and relaxation was −2.0%. The properties of the obtained film are shown in Table 3.

Example 10:
Using a polyester raw material in which the polyester raw material (1), the polyester raw material (3) and the polyester raw material (4) are mixed in a ratio of 65.5: 21.5: 13.0, the heat treatment temperature is 205 ° C. and 0.0%. A polyester film was obtained by the same method as in Example 1 except that the thickness was 175 μm. The properties of the obtained film are shown in Table 3.

Example 11:
The polyester raw material (2), the polyester raw material (3), and the polyester raw material (4) were mixed in the same manner as in Example 1 except that the polyester raw material was mixed at a ratio of 25.8: 57.2: 17.0. A film was obtained. The properties of the obtained film are shown in Table 3.

Example 12:
Example 1 except that the polyester raw material (1), the polyester raw material (3), and the polyester raw material (4) were mixed at a ratio of 82.8: 7.2: 10.0, and the thickness was 175 μm. A polyester film was obtained by the same method. The properties of the obtained film are shown in Table 3.

Example 13:
Example 1 except that the polyester raw material (1), the polyester raw material (3) and the polyester raw material (4) were mixed at a ratio of 86.3: 10.7: 3.0 and the thickness was 175 μm. A polyester film was obtained by the same method. The properties of the obtained film are shown in Table 3.

Example 14:
A polyester film was obtained by the same method as in Example 1 except that the thickness was 75 μm. The properties of the obtained film are shown in Table 3.

Comparative Example 1:
Example 1 except that the polyester raw material (1), the polyester raw material (3), and the polyester raw material (4) were mixed at a ratio of 68.3: 10.7: 21.0 and the thickness was 175 μm. A polyester film was obtained by the same method. Although the characteristic of the obtained film is shown in Table 4, sufficient flame retardance was not expressed.

Comparative Example 2:
The polyester raw material (2), the polyester raw material (3), and the polyester raw material (4) were mixed in the same manner as in Example 1 except that the polyester raw material was mixed at a ratio of 34.8: 23.2: 42.0. A film was obtained. Although the characteristic of the obtained film is shown in Table 4, sufficient flame retardance was not expressed.

  The film of the present invention is, for example, a packaging material, an electrical insulating material, a metal vapor deposition material, a plate making material, a magnetic recording material, a display material, a transfer material, a window pasting material, a battery label or a flat cable of a personal computer or a mobile phone, an illumination part. It can be suitably used in many applications such as a material and a wiring part material application of a collecting electrode called a bus bar.

Claims (1)

It contains a phosphorus-based flame retardant compound and a white pigment, and the ratio (void occupancy / phosphorus element content) between the void occupancy (%) and the phosphorus element content (wt%) is 20.0 or less. White flame-retardant polyester film characterized by