JPH0120666B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flame-retardant polyester film and a method for producing the same, and more particularly, it comprises applying a specific flame-retardant coating composition to at least one side of a biaxially oriented polyester film; The present invention relates to a flame-retardant polyester film on which a flame-retardant coating is formed that has sufficient adhesive strength, organic solvent resistance, flexibility, and blocking resistance, and a method for rapidly and efficiently producing the flame-retardant polyester film.

BACKGROUND ART Conventionally, a method of forming a flame-retardant coating on a polyester film has been known as a method of making polyester film flame-retardant. In this method, for example, a flame retardant (for example, a halogen such as pentabromophenol or tetrabromo phthalic anhydride) which is compatible with the binder (for example, alkyd resin, amino resin, epoxy resin, or other thermosetting resin) is added A method is known in which a flame retardant film is formed by applying an organic solvent solution containing a flame retardant auxiliary agent such as antimony trioxide or a phosphorous compound. However, with this method, the adhesion between the film and the polyester film is not necessarily sufficient, and the flexibility of the film is low.
It has the disadvantage that cracks are likely to occur in the formed film due to bending of the film.

Furthermore, when a thermoplastic resin is used as a binder, although the adhesion and flexibility are improved, the organic solvent resistance and blocking resistance are significantly inferior. It is virtually impossible to apply sticky organic solvent solutions.

Therefore, a method for producing a flame-retardant polyester film that improves these drawbacks has been proposed in JP-A-50-34064. The method disclosed in JP-A No. 50-34064 develops the necessary coating performance by applying a specific flame-retardant coating liquid and then drying it at a temperature sufficient to cure the alkyl etherified melamine initial condensation polymer. The drying curing conditions described in the examples are extremely harsh conditions of 150°C for 5 minutes. However, when such dry curing conditions are adopted, the coating speed is significantly reduced, resulting in poor productivity, and also affects the performance of the polyester film as a base material.

Purpose of the Invention As a result of intensive research, the present inventors added a specific organic phosphorus compound to the coating solution in order to improve the drawbacks of the method proposed in JP-A No. 50-34064 and improve its productivity. The inventors have discovered that this makes it possible to improve productivity and that the resulting polyester film has excellent physical properties, leading to the present invention.

An object of the present invention is to provide a flame-retardant polyester film and an improved method for producing the same.

Structure/Effects of the Invention The objects of the present invention are to form a mixture of a linear saturated copolymerized polyester and an alkyl etherified melamine-treated condensate in a weight ratio of 4:6 to 2:8, and a mixture having a melting point of 60°C or higher. A flame retardant coating composition prepared by adding an organic phosphorus compound having a polycondensation catalytic action in an organic solvent solution containing a halogenated flame retardant in an amount of 5 to 25% by weight based on the mixture is applied to at least one biaxially oriented polyester film. This is achieved by applying it to one side and forming a film.

The polyester film referred to in the present invention refers to a polyethylene terephthalate film and a polyethylene 2,6-naphthalate film.
- Naphthalate is not only polyester in which terephthalic acid or naphthalene dicarboxylic acid and ethylene glycol are combined, but also polyester in which more than 80% of the repeating units are ethylene terephthalate or ethylene 2,6-
It may also be a copolyester consisting of naphthalate units, in which 20% or less of the repeating units are other components.

The linear saturated copolymerized polyester, which is one of the binders used in the present invention, includes acid components such as terephthalic acid, isophthalic acid, diphenyl ether dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and 2,7-naphthalene. One or more acids selected from aromatic dicarboxylic acids such as dicarboxylic acids, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, oxalic acid, azelaic acid, etc., and glycol components such as ethylene glycol and propylene glycol. , butanediol, heptanediol, hexanediol, 2-methyl-1,
Linear amorphous condensed by a combination with one or more glycols selected from 3-propanediol, neopentyl glycol, diethylene glycol, triethylene glycol, 2,2,4,4-tetramethylcyclobutanediol, etc. Made of polyester.

The most common alkyl etherified melamine initial condensate is methyl or butyl etherified melamine.

The mixing ratio of the linear saturated copolymerized polyester and the alkyl etherified melamine initial condensate is 4:6 to 2:8. If this mixing ratio is not satisfied, for example, the ratio of the linear saturated copolymer polyester is too small, the adhesion and flexibility of the formed film to the film will decrease (for example, if the mixing ratio is 1:9, the bending of the film will cause small particles to form on the applied film). (causing cracks, etc.), making it unsuitable as a coating agent for films with excellent flexibility. Moreover, if this ratio is increased, for example, 5:5, the compatibility between the two will be poor and it will be difficult to obtain a uniform coating, which is not preferable. If the mixing ratio of the linear saturated copolymerized polyester is further increased to 6:4 or more, a uniform coating can be obtained again, but
On the other hand, the organic solvent resistance of this formed film is extremely poor, and if it is necessary to further overcoat with a general-purpose organic solvent solution, the formed film will be dissolved by the organic solvent contained in this solution, resulting in a very uneven film. I can't. That is, only when the mixing ratio of the organic solvent-soluble linear saturated copolymerized polyester and the alkyl etherified melamine initial condensate is 4:6 to 2:8, the adhesion to the polyester film, flexibility, and organic solvent resistance are improved. It is possible to satisfy all sexual needs.

The halogen-based flame retardant used in the present invention must have a melting point of 60°C or higher in consideration of the blocking resistance of the resulting flame-retardant film, and the halogen content must be 50% by weight from the viewpoint of flame-retardant properties. The above-mentioned halogen compounds, halogenated phosphate esters, and the like are preferred. For example, polycarbonate oligomers of tetrahalogenated phthalic anhydride, tetrahalogenated bisphenol A, hexahalogenated benzene, octahalogenated diphenyl, and tetrabromobisphenol A (number average degree of polymerization is 15
Below, preferred examples include 3 to 10), percyclohalogenated cyclodecane, and the like. The amount used can be arbitrarily determined depending on the desired degree of flame retardancy within a range that does not significantly reduce the properties of the formed coating, but it is usually appropriate to use it in an amount of 50 to 200% by weight based on the binder.

As the organic phosphorus compound used in the present invention, acidic phosphoric acid esters having a catalytic effect on melamine are suitable, such as isopropyl acid phosphate, butyl acid phosphate, dibutyl phosphate, and monobutyl phosphate. Examples include those that can be used in organic solvents, such as ester and octyl acid phosphate.

The amount of the organic phosphorus compound to be used is suitably 5 to 25 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the resin content excluding the flame retardant in the solution. By using the amount of the organic phosphorus compound within this range, the performance of the coating film can be expressed under mild drying curing conditions, such as drying at 120° to 130°C within 1 minute after application of the flame retardant solution. However, if it is less than 5 parts by weight, the drying curing conditions will be severe, and if it is more than 25 parts by weight, the coating film will lack flexibility and will be prone to cracking due to bending, so both are unfavorable.

The organic solvent used in the present invention includes:
For example, methyl ethyl ketone, cyclohexanone,
Methyl acetate, ethyl acetate, amyl acetate, isobutyl acetate, n-butyl acetate, cellosolve acetate, dioxane, tetrahydrofuran, chloroform, trichlene, orthochlorobenzene,
Examples include benzene, toluene, xylene, 2-nitropropane, nitromethane, metacresol, and the like. These may be used alone or in combination.

In the present invention, the flame-retardant coating composition is produced by adding and dissolving a mixture of linear saturated copolymerized polyester and alkyl etherified melamine initial condensate, an organic phosphorus compound, and a halogen flame retardant in a predetermined proportion in the organic solvent. do. The solid content concentration in the resulting solution is preferably 10 to 60% by weight, more preferably 20 to 50% by weight.

The flame-retardant coating composition of the present invention can fully exhibit its characteristics by coating it on at least one side of a biaxially stretched polyester film to form a flame-retardant coating. That is, the flame retardant coating has particularly excellent adhesion to the polyester film and has a large flame retardant effect.

Furthermore, a flame-retardant polyester film can be formed by coating and drying this composition on a biaxially stretched polyester film, but even when the drying temperature is 130°C or lower, it has poor adhesion, flexibility, solvent resistance, and blocking resistance. It exhibits the ability to form a flame-retardant film with excellent properties.

In the method of the present invention, any coating method such as a gravure roll coater, a kiss coater, a reverse roll coater, or a dip coater can be used for coating the composition. Also, the drying temperature is 130℃
The drying time is preferably 100 to 130°C, and the drying time varies depending on the drying temperature, but is usually 3 minutes or less, preferably 1 minute or less. However, it is desirable that the drying time be at least 20 seconds.

EXAMPLES The present invention will be specifically explained below with reference to Examples.
Note that "parts", percentages, and ratios in the examples are based on weight, and are based on OI (Minimum
Oxygen Index) values are based on the method of ASTMD2863-70. In addition, the adhesion between polyester film and coating can be evaluated using the so-called cross-cut test method.
In other words, make 100 1 mm x 1 mm gongs on the surface with a razor blade, peel off the part with cellophane tape, find the number N of gongs that remain without peeling off, and evaluate the adhesion quality with N/100. I judged it. The blocking property was determined by the method of JIS 2-0219-1957, and the flexibility of the film was determined by bending the film 180 degrees and determining the occurrence of cracks in the folded portion.

Comparative example Organic solvent-soluble linear saturated copolycondensation polyester resin "Vylon 30" (product) with a molecular weight of approximately 20,000 obtained by the four-component copolycondensation of dimethyl terephthalate, dimethyl sebacate, ethylene glycol, and neopentyl glycol. Name: Toyobo Co., Ltd.) and butyl etherified melamine "Melan"
20'' (trade name: manufactured by Hitachi Chemical Co., Ltd.) at a resin ratio of 4:6, diluted and dissolved with a solvent of toluene: methyl ethyl ketone: ethyl acetate = 1:1:1 to remove the total solid content. It was set at 30%. Next, 2,2-(4,4'-dihydroxy-tetrabromodiphenyl)propane (hereinafter abbreviated as TBA) was added to this solution at a ratio of 120% based on the resin content, and the mixture was stirred and dissolved.
The obtained solution was applied to a biaxially stretched polyethylene terephthalate film with a thickness of 50 μm using a bar coater, and dried at 130° C. for 1 minute. The thickness of the dried film was 20μ.

The obtained film had an OI value of 25, but was prone to blocking, had poor solvent resistance, and had insufficient curing of the adhesive component.

Example 1 A flame retardant film was prepared in exactly the same manner as in Comparative Example except that TBA was reduced to 80% based on the resin content and butyl acid phosphate was added at 20% based on the resin content.

The obtained film had an OI value of 25, and when the solvent resistance of the film side was tested with acetone, methyl ethyl ketone, ethyl acetate, and toluene, it was found that it was hardly dissolved. Next, when the coating surface was further overcoated with a solution containing the above flame retardant, no problem occurred. Also, the cross cut result is
It was 100/100, had excellent blocking resistance, and was extremely flexible.

Example 2 “Espel 1510” (trade name: manufactured by Hitachi Chemical Co., Ltd.) as a linear saturated copolymerized polyester soluble in organic solvents
and "Nikaratsuku MS-11" (trade name: manufactured by Sanwa Chemical Co., Ltd.) as a methyl etherified melamine initial condensate were mixed at a solid content ratio of 3:7, In addition, TBA in an amount of 66% based on the resin content and 20% based on the resin content
add butyl acid phosphate in an amount of %,
Toluene: Methyl ethyl ketone: Ethyl acetate =
A solution with a total solid content of 40% was prepared by diluting and dissolving with a 1:1:1 solvent. The obtained solution was applied onto a biaxially stretched polyethylene terephthalate film having a thickness of 50 μm using a bar coater, and dried at 130° C. for 1 minute. The thickness of the dried film was 12μ.

The obtained film had excellent solvent resistance, no blocking, and excellent adhesion and flexibility.
Moreover, this OI value was 23, indicating excellent flame retardancy.

Claims (1)

[Claims] 1. A mixture consisting of a linear saturated copolymerized polyester and an alkyl etherified metamine initial condensate in a weight ratio of 4:6 to 2:8 and a melting point of 60°C.
A flame-retardant coating using a flame-retardant coating composition obtained by adding 5 to 25% by weight of an organic neighboring compound having a polycondensation catalytic action to the organic solvent solution containing the above-mentioned halogen-based flame retardant. A flame-retardant polyester film formed on at least one side of a biaxially stretched polyester film. 2 A mixture consisting of a linear saturated copolymerized polyester and an alkyl etherified metamine initial condensate in a weight ratio of 4:6 to 2:8 and a melting point of 60°C
A flame retardant coating composition prepared by adding an organic neighboring compound having a condensation polymerization catalytic action to an organic solvent solution containing the above halogenated flame retardant in an amount of 5 to 25% by weight based on the mixture is applied to a biaxially oriented polyester film. 1. A method for producing a flame-retardant polyester film, which comprises coating on at least one side of the film and drying to form a flame-retardant film on the film.