JPH0679846A - Polyester film - Google Patents

Abstract

PURPOSE:To attempt to improve flame retardancy while heat resistance and hydrolysis resistance are kept by laminating linear polyesters A and C each contg. 0.5-5.0% flame-retardant element and a linear polyester B contg. less than 0-0.5% flame-retardant element in an order of A/B/C and orienting them in one direction. CONSTITUTION:A three-layered laminated film consists of linear polyester A and C layers 1 and 3 each contg. 0.5-5.0wt.% flame-retardant element and a polyester B layer 2 contg. less than 0-0.5wt.% flame-retardant element. In addition, the linear polyesters A, B and C are laminated in an order of A/B/C in the thickness direction and are oriented at least in one direction. The linear polyesters A, B and C each consists of an acid ingredient wherein an arom. dicarboxylic acid is a main ingredient and a glycol ingredient. In addition, the flame-retardant element is phosphorus, halogene elements or elements such as antimony which turn into a flame-retardant compd. such as antimony trioxide etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flame-retardant oriented polyester film. More specifically, the present invention relates to the appearance, transparency, mechanical strength, and the like of the oriented polyester film.
Underwriters Laboratories (UN, USA) that does not impair characteristics such as electrical properties, chemical resistance, and high-order processability
The present invention provides an oriented polyester film having a flame retardancy level corresponding to VTM-0 defined in the standard UL-94 of DERWRITER LABORATORIES).

In particular, printed boards, printed circuit boards, membrane switch boards, touch keyboard boards, transparent window materials for home appliances, terminal boards as electric component materials, interlayer papers,
Suitable for tapes, wire coatings, coil spacers, connectors, tubes, enclosure materials specified by UL, barrier materials, decorative parts, dial windows, meter materials, transparent cover materials, or electrical insulation materials. The present invention provides a uniaxially or biaxially oriented polyester film having flammability.

[0003]

2. Description of the Related Art As means for making a polyester molded product flame-retardant, a halogen-containing compound, a phosphorus-containing compound, a metal oxide, etc. are added to polyester and mixed and melt-extruded, or the flame-retardant property is imparted to the surface of the molded product. The method of applying the compound is disclosed in JP-B-49-45295 and JP-B-55-509.
85, Japanese Patent Publication 60-21184, or Japanese Patent Publication 59-4
Although proposed in Japanese Patent No. 2692, the problems of these conventional techniques are disclosed in detail in Japanese Patent Application Laid-Open No. 62-277429.

[0004]

[Problems to be Solved by the Invention] That is, JP-A-62-62
As disclosed in JP-A-277429, increasing the phosphorus content in a polyester molded product or film improves the flame retardancy level, but lowers the melting point of the polyester chips and deteriorates the extrusion moldability. The thickness unevenness of the film increases, or the film softens in the tenter during film formation, the film flutters and the film cannot be formed, and even if it becomes a film, heat resistance decreases, hydrolysis resistance decreases, It cannot be used in the above-mentioned industrial applications.

In order to solve such a problem, various techniques are disclosed in Japanese Patent Laid-Open Nos. 51-82392 and 62-2774.
29, JP-A-63-133589, or JP-A-2-
Although proposed in Japanese Patent No. 53821, the flame retardancy level is VTM-2 class defined by UL-94, and the flame retardancy level required by the present inventors is VTM-0. I haven't arrived.

In view of the above-mentioned problems and the current level of the prior art, the present invention has the same high heat resistance and hydrolysis resistance as a general polyester film, particularly polyethylene terephthalate film, and further higher flame retardancy. It is intended to provide a polyester film having the same.

[0007]

The polyester film of the present invention for this purpose has linear polyesters A and C containing 0.5% by weight or more and 5.0% by weight or less of a flame retardant element and 0 to a flame retardant element. A linear polyester B containing less than 0.5% by weight and a flame-retardant polyester film oriented in at least one direction, which are laminated in the order of A / B / C in the thickness direction.

The linear polyesters A, B and C referred to in the present invention
Is a linear polyester composed of an acid component mainly containing an aromatic dicarboxylic acid and a glycol component. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, 4,4′-diphenyl sulfone dicarboxylic acid, 4, 4'-diphenyldicarboxylic acid, 4,4'-diphenylethanedicarboxylic acid and the like can be mentioned.
Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferable, and terephthalic acid is particularly preferable.

The glycol component is preferably alkylene glycol, and examples thereof include ethylene glycol, tetramethylene glycol and hexamethylene glycol. Of these, ethylene glycol is particularly preferable. That is, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferable, and polyethylene terephthalate is particularly preferable.

Further, in the linear polyester in the present invention, a part of the acid component of the above ester or a part of the glycol component is other dicarboxylic acid component such as isophthalic acid, sodium sulfoisophthalic acid, diphenoxydiethane. Dicarboxylic acid, adipic acid, sebacic acid, etc., or other glycol component such as diethylene glycol, propylene glycol, trimethylene glycol,
Tetramethylene glycol, neopentyl glycol,
It may be a copolyester substituted with 1,4-cyclohexanedimethal, polyethylene glycol, a bisphenol A component or the like. Further, the linear polyester referred to in the present invention may be a mixture of one or more linear polyesters composed of the ester component and glycol component described above.

The linear polyesters A and C must contain 0.5% by weight or more and 5.0% by weight or less of a flame-retardant element (also referred to as a flame-retardant element), while the linear polyester B is difficult. Do not include more than 0.5% by weight of flammable elements. The flame-retardant element here is an element such as phosphorus, a halogenated element or the like, or an antimony which becomes a flame-retardant compound such as antimony trioxide, aluminum hydroxide or tin oxide hydrate, aluminum, or an element such as tin, These flame-retardant elements and flame-retardant compounds are described in detail in "Making plastics flame-retardant" (written by Eiita, published by Nikkan Kogyo Shimbun, published in 1978). Of these, phosphorus and halogen elements are preferable, and it is particularly preferable that these elements are copolymerized as a compound with polyester. Among them, phosphorus element is particularly preferable, and among them, as the phosphorus compound containing phosphorus element, compounds represented by the following general formulas 7 to 9 or 11 and 12 are particularly preferable. Furthermore, it is particularly preferable that the polyester is copolymerized in the polyester or a mixture of the copolymer and the polyester not copolymerized.

The preferred phosphorus compound used in the present invention is a phosphorus compound having two ester-forming functional groups, and is a phosphonate represented by Chemical formula 7, a phosphonate represented by Chemical formula 8, or a phosphine represented by Chemical formula 9. An oxide is mentioned.

[0013]

[Chemical 7]

[0014]

[Chemical 8]

[0015]

[Chemical 9]

In the formula, R ₁ and R ₅ are the same or different groups and represent a hydrocarbon group having 1 to 18 carbon atoms,
R ₂ and R ₃ are the same or different groups and each represents a hydrocarbon group having 1 to 18 carbon atoms, a hydroxyalkyl group having 1 to 18 carbon atoms or a hydrogen atom, and A ₁ and A _{2 each} have carbon number Represents a divalent or trivalent organic residue of 2 to 8, R ₄ represents a carboxyl group, a hydroxyl group or an ester thereof, and R ₆ represents a carboxyl group, a hydroxyl group or an ester thereof, or the following chemical formula 10 Represents a divalent ester-forming functional group which forms a ring with A ₂ via a group represented by

[0017]

[Chemical 10]

Preferred examples of the phosphorus compound represented by the above chemical formula 7 include dimethyl phenylphosphonate, diphenyl phenylphosphonate and the like.

Preferred examples of the phosphorus compound of the above chemical formula 8 are (2-carboxyethyl) methylphosphinic acid,
Methyl (2-methoxycarbonylethyl) methylphosphinate, (2-carboxyethyl) phenylphosphinic acid, methyl (2-methoxycarbonylethyl) phenylphosphinate, (4-methoxycarbonylphenyl) phenylphosphine Examples include methyl inate, (2- (β-hydroxyethoxycarbonyl) ethyl) methylphosphinic acid, and ethylene glycol esters thereof.

Preferred examples of the phosphorus compound of the above chemical formula 9 are (1,2 dicarboxyethyl) dimethylphosphine oxide, (2,3 dicarboxypropyl) dimethylphosphine oxide and (1,2 dimethoxycarbonylethyl) dimethyl. Phosphine oxide, (2,3 dimethoxycarbonylethyl) dimethylphosphine oxide,
Examples include (1,2 di (β-hydroxyethoxycarbonyl) ethyl) dimethylphosphine oxide and (2,3 di (β-hydroxyethoxycarbonyl) ethyl) dimethylphosphine oxide.

Among these compounds, the compound of Chemical formula 8 is particularly preferable since it has a good copolymerization reactivity with polyester and has little scattering during the polymerization reaction.

Still another preferable phosphorus compound is
A monoalkyl acid phosphate and a dialkyl acid phosphate represented by the following chemical formulas 11 and 12 or a mixture thereof.

[0023]

[Chemical 11]

[0024]

[Chemical 12] (Wherein R is an alkyl group having up to 8 carbon atoms)

Among the compounds of the above chemical formula 8, especially the following chemical formula 1
Chemical formula 3 and chemical formula 14 are preferable, and they may be used in combination or in combination with other phosphorus compounds.

[0026]

[Chemical 13]

[0027]

[Chemical 14]

The preferable content of elemental phosphorus is 0.5 to 5.0% by weight, more preferably 1.0 to 2.0% by weight in the linear polyesters A and C, and 0.1% in the linear polyester B. It is less than 5% by weight, more preferably less than 0.2% by weight. If the phosphorus element content of the linear polyesters A and C is less than 0.5% by weight, VTM-0 specified by UL-94
If it exceeds 5.0% by weight, the hydrolysis resistance, heat resistance, etc. are deteriorated, or the melting point is lowered, and the film sticks to the stretching roll during film formation. Film formation becomes extremely difficult. Linear polyester B
When the content of phosphorus element is 0.5% by weight or more, the quality of the film such as hydrolysis resistance and heat resistance is significantly deteriorated, and the excellent properties of the polyester film are impaired.

The method of adding or copolymerizing a compound containing a refractory element to a linear polyester is not particularly limited. For example, JP-A-51-82392 and JP-A-2-
53821, JP-A-63-133589, JP-A-62-
It can be carried out by a conventional polymerization method disclosed in Japanese Patent No. 277429.

The polyester of the present invention may be added with conventionally known additives to such an extent that the object of the present invention is not impaired. For example, pigments, stabilizers, plasticizers, antistatic agents such as lithium alkylbenzene sulfonates, lubricants, etc., which are commonly used in polyester films, may be added.

The flame-retardant polyester film of the present invention is
It is essential that the linear polyester A, the linear polyester B, and the linear polyester C are laminated in A / B / C in the thickness direction in order to conform to the flame-retardant UL-94 and VTM-0. . A / B, B / A / C, A / C / B, B / A
The flame retardancy level decreases in a laminated structure such as / B. The types and amounts of the flame-retardant elements of the linear polyesters A and C may be the same or different, but the same is advantageous in film formation, and in normal use, the front and back of the film can be distinguished from each other. None preferred.

A method of laminating the linear polyesters A, B and C may be a method of laminating each other with an adhesive or a method of directly laminating the polymers of each other in a molten state without interposing an adhesive. From the viewpoint of flame retardancy, flexibility as a film, mechanical properties, and processability, it is most preferable to laminate in a molten state.

That is, the typical basic constitution of the flame-retardant polyester film of the present invention is as shown in FIG.
In FIG. 1, 1 is a linear polyester A layer containing 0.5 to 5.0% by weight of a flame retardant element, and 2 is a flame retardant element content of 0 to 0.
A linear polyester B layer of less than 0.5% by weight represents a linear polyester C layer containing 0.5 to 5.0% by weight of a flame retardant element, and these A, B and C layers are A /
They are stacked in the order of B / C.

The thickness of the linear polyesters A and C in the film of the present invention is preferably 0.01 to 3 times, more preferably 0.05 to 1 times the thickness of the linear polyester B, and A , The specific thickness of C is preferably 0.0
It is 5 to 200 μm, and more preferably 1 to 100 μm. If the thickness of A and C is less than 0.01 times the thickness of B, or less than 0.5 μm, the target UL-94, VT
Does not conform to M-0, exceeds 3 times, or 2
If it exceeds 00 μm, the properties required for the polyester film such as heat resistance and hydrolysis resistance cannot be obtained. A
The thickness of C and C may be the same or different,
Since there is no difference between the front side and the back side in the film formation and the film, it is preferable to have the same thickness as much as possible. The total thickness of the film of the present invention is not particularly limited, but is 10 to 500 μm.
m is preferred.

In the present invention, the film oriented in at least one direction means the above-mentioned laminated polyester A / B.
/ C is oriented in at least one direction, preferably in the vertical and horizontal directions, and the degree of orientation is not particularly limited, but in order to exhibit the characteristics of the polyester film, the surface defined by the following formula The birefringence Δn _{p of the} orientation is preferably 0.1 or more. Δn _p = (nγ + nβ) / 2−nα where n is the refractive index, subscripts α, β, and γ are the three optical axes of the polyester, and are defined as nα ≦ nβ ≦ nγ. In the oriented polyester film, α is in the thickness direction, and β and γ are in the film plane. The refractive index in three directions is
It can be measured using an Appe refractometer and an analyzer.

The method of film formation (film formation) of the film of the present invention is not particularly limited, but preferably, polyesters A, B and C are respectively fed to extruders A, B and C by a conventional method, and T Before entering the die or in the T-die stacking die, A
/ B / C in three layers, and the melted sheet is adhered and solidified by electrostatic force on a drum cooled to a drum surface temperature of 10 to 60 ° C., and the unstretched film is heated to 80 to 120 ° C.
The film is guided to a roll group heated to 2 to 5 times in the longitudinal direction in the longitudinal direction and cooled by a roll group at 20 to 50 ° C. Subsequently, the film is guided to a tenter while holding both ends of the film with clips, and transversely stretched in a direction perpendicular to the longitudinal direction in an atmosphere heated to 90 to 140 ° C. The stretching ratio is 2 to 5 times in each of the length and width, and the area ratio is preferably 6 to 20 times. If the area magnification is less than 6 times, whitening is not sufficiently performed, and if it exceeds 20 times, tearing tends to occur during stretching. In order to impart flatness and dimensional stability to the biaxially stretched film in this way, 15
The film is heat-set at 0 to 240 ° C., uniformly cooled and then cooled to room temperature to obtain the film of the present invention.

When the types and amounts of the flame retardants of polyesters A and C are the same, as a matter of course, only the extruder A and the extruder B can be used to perform A / B / C three-layer lamination.

[0038]

According to the polyester film of the present invention, a linear polyester A containing a specific amount of a flame retardant element,
C and a linear polyester B containing a flame-retardant element less than a specific amount are laminated in the order of A / B / C to obtain a flame-retardant polyester film oriented in at least one direction. Excellent flame retardancy can be imparted while maintaining heat resistance, hydrolysis resistance, mechanical properties, processability, chemical resistance, etc., and as shown in the examples described below, UL-94 ranks VTM-0. Can be fully achieved.

[0039]

【Example】

Examples 1 to 10 and Comparative Examples 1 to 6 Bis-β-hydroxyethyl terephthalate and its low polymers were synthesized from terephthalic acid and ethylene glycol by a direct esterification method to obtain antimony trioxide and (2-
After adding ethylene glycol ester of carboxyethyl) methylphosphinic acid to the polymer in an amount corresponding to the phosphorus element amount shown in Table 1, a polycondensation reaction is carried out in the usual manner to give a polyester having an intrinsic viscosity of 0.64 to 0.68. Obtained. The polymer chips were pre-crystallized and then vacuum dried at 170 ° C. 270 to 28 the chips using the extruders A and B
It is melted at 0 ° C, laminated in the order of A / B / C in a T-die in three layers, extruded and molded into a sheet on a cooling drum at 28 ° C, and then stretched 3.2 times in the longitudinal direction at 90 ° C. Then, the film was stretched in the transverse direction 3.3 times at 125 ° C., further heat-treated at 225 ° C. to shrink in the transverse direction by 5.3%, cooled, and wound up.
A biaxially stretched film having an oriented thickness of 100 μm was obtained. The C layer was made of the same polymer and had the same thickness as the A layer. The phosphorus concentration and thickness of each layer are changed within the range specified in the present invention, and U
The rank and thickness unevenness of L-94 were evaluated. The results are shown in Table 1. The uneven thickness is evaluated by ± 7%.
The case was within the range of ⊚, the case of within ± 10% was marked with ◯, the case of exceeding ± 10% was marked with x, and the range of ◯ or above was regarded as good.

As a comparative example, the phosphorus concentration of the B layer was out of the range specified in the present invention (Comparative Example 1), the A layer,
The phosphorus concentration of the C layer is outside the range of the present invention (Comparative Example 2,
3 and 4), and further, only the extruder B was used to form films as a single film without being laminated in three layers (Comparative Examples 5 and 6). In Comparative Examples 5 and 6, the single film was too soft in the tenter when stretched in the transverse direction and could not be formed into a clean film, and a long film could not be produced.

The films of the above Examples and Comparative Examples were UL-
The flame retardancy level was evaluated by the 94 VTM method. The results are shown in Table 1. As shown in Table 1, in the film of the present invention, which is sandwiched from both sides with a layer containing a large amount of phosphorus and containing three layers, the thickness of the film is small and the target UL-94, UTM-0. Although a high flame retardancy was obtained, it was not possible to obtain a high flame retardancy while maintaining good thickness unevenness in the comparative example outside the scope of the present invention.

[0042]

[Table 1]

[Brief description of drawings]

FIG. 1 is a sectional view of a three-layer laminated film of the present invention.

[Explanation of Codes] 1 Layer A containing 0.5 to 5.0 wt% flame retardant element Layer 2 containing 0.5 to 5.0 wt% flame retardant element 0.5 to 5.0 flame retardant element Layer C containing wt%

Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location // C08J 5/18 CFD 9267-4F B29K 67:00 B29L 7:00 4F (72) Inventor Masaaki Sudo Shiga Prefecture 1-1-1, Sonoyama, Otsu City Toray Co., Ltd. Shiga Plant

Claims (10)

[Claims] 1. A linear polyester A, C containing 0.5% by weight or more and 5.0% by weight or less of a flame retardant element and 0 or more flame retardant elements.
A flame-retardant polyester film oriented in at least one direction, which is obtained by laminating a linear polyester B containing less than 0.5% by weight in the order of A / B / C in the thickness direction. 2. The flame-retardant polyester film according to claim 1, wherein the flame-retardant element is phosphorus or halogen. 3. The flame-retardant polyester film according to claim 1, wherein a flame-retardant compound containing phosphorus or halogen as a flame-retardant element is copolymerized with polyesters A, C and B. 4. The difficulty according to claim 1, wherein the linear polyesters A, C and B are linear polyesters containing an aromatic dicarboxylic acid as a main acid component and ethylene glycol as a main diol component. Flammable polyester film. 5. The flame-retardant polyester film according to claim 4, wherein the aromatic dicarboxylic acid of the linear polyesters A, C and B is terephthalic acid or 2,6-naphthalenedicarboxylic acid. 6. A flame retardant containing a flame retardant element is represented by the following chemical formula 1, chemical formula 2
The flame-retardant polyester film according to any one of claims 1 to 5, which is one or more compounds selected from the phosphorus compounds represented by Chemical formula 3 below. [Chemical 1] [Chemical 2] [Chemical 3] In the formula, R ₁ and R ₅ are the same or different groups each representing a hydrocarbon group having 1 to 18 carbon atoms, and R ₂ and R ₃ are the same or different groups each having 1 carbon number. ~ 18
Represents a hydrocarbon group or a hydroxyalkyl group having 1 to 18 carbon atoms or a hydrogen atom, and A ₁ and A _{2 each} have 2 to 8 carbon atoms.
Represents a divalent or trivalent organic residue, R ₄ represents a carboxyl group, a hydroxyl group or an ester thereof, and R ₆ represents a carboxyl group, a hydroxyl group or an ester thereof,
Alternatively, they represent divalent ester-forming functional groups that form a ring with A ₂ via a group represented by the following chemical formula 4. [Chemical 4] 7. The flame retardant containing a flame retardant element is any one of a monoalkyl acid phosphate and a dialkyl acid phosphate represented by the following Chemical Formulas 5 and 6 or a mixture of both. Flame-retardant polyester film described in Crab. [Chemical 5] [Chemical 6] (In the formula, R is an alkyl group having 1 to 8 carbon atoms). 8. The linear polyesters A and C contain 1.0 to 2.0% by weight of phosphorus element, and the linear polyester B contains 0 to 0.2% by weight of phosphorus element. Flame-retardant polyester film described. 9. The thickness of the linear polyesters A and C is 0.01 to 3 times the thickness of the linear polyester B, and the thickness of the linear polyesters A and C is 0.5 μm or more and 200 μm or less. A flame-retardant polyester film according to any one of 1 to 8. 10. The thickness of the linear polyesters A and C is 0.05 to 1 times the thickness of the linear polyester B, and the thickness of the linear polyesters A and C is 1 μm or more and 100 μm or less. Flame-retardant polyester film.