JP2006335851A - Polyester film for automobile interior material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automobile interior material which has a sufficient rigidity and heat resistance, is lightweight and has a high deep-draw moldability without using any glass fiber mat. <P>SOLUTION: A polyester film used as the automobile interior material has a melting point of 200-270°C and a plane orientation coefficient of 0.05-0.11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyester film used for a component of a molded ceiling covering an interior of an automobile interior material, particularly the interior side of a roof of a car body of an automobile. More specifically, the present invention relates to an automobile interior material that involves drawing with a mold in a machining process, and particularly to a polyester film used for a component member of a molded ceiling of an automobile.

  2. Description of the Related Art Conventionally, as a core material for a molded ceiling of an automobile interior, a thermosetting resin and organic fiber that are kneaded and hot pressed with a mold has been used. For example, a glass fiber mat is affixed on a surface of a thermoforming plate urethane foam with a hot melt film interposed therebetween, and a polyester nonwoven fabric or a cover paper is affixed on the surface of the glass fiber mat with a hot melt film interposed therebetween. A molded ceiling is used. In this case, by sticking a non-stretchable glass fiber mat to both surfaces of the plate-like urethane foam, the rigidity is maintained and the weight is reduced, and deformation in a humid heat environment is prevented.

  Automotive interior materials, especially molded ceiling components, have good heat resistance, heat insulation, sound absorption and shape stability, are lightweight and highly rigid, can be recycled, and have unpleasant odors and harmful combustion gases. It is desirable not to occur. However, glass fiber mats that have been used in the prior art are irritating to the skin during handling, workability is poor, there are concerns about adverse effects on the human body, and recycling is not possible, so there is a burden on the environment. high.

JP-A-8-1877 JP 7-68689 A JP 2003-34192 A

  An object of the present invention is to provide an automobile interior material that has sufficient rigidity and heat resistance without using a glass fiber mat, is lightweight, and has a high degree of deep drawing processability.

  That is, the present invention is a polyester film for automobile interior materials having a melting point of 200 to 270 ° C. and a plane orientation coefficient of 0.05 to 0.11.

  ADVANTAGE OF THE INVENTION According to this invention, it can provide the automotive interior material which has sufficient rigidity and heat resistance without using a glass fiber mat, and has a light weight and high deep drawing processability.

Hereinafter, the present invention will be described in detail.
[polyester]
The polyester film for automobile interior materials according to the present invention comprises a polyester film. This polyester is a general term for polymers in which a monomer residue, which is a main bond in the main chain, and a covalent bond that connects the monomer residue is an ester bond. Polyester can be obtained by polycondensation reaction of a dicarboxylic acid compound and a dihydroxy compound, or a dicarboxylic acid ester compound and a dihydroxy compound.

  Examples of the dicarboxylic acid compound include fragrances such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodium sulfoterephthalic acid, and phthalic acid. Aliphatic dicarboxylic acids, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids, and paraoxybenzoic acid and other oxycarboxylic acids Can be mentioned.

  Examples of the dicarboxylic acid ester compounds include esterified products of the above dicarboxylic acid compounds such as dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethyl methyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, and dimethyl adipate. , Diethyl maleate, and dimethyl dimer.

  On the other hand, as the dihydroxy compound, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6 -Aliphatic dihydroxy compounds such as hexanediol and neopentyl glycol, polyoxyalkylene glycols such as diethylene glycol, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, alicyclic dihydroxy compounds such as cyclohexanedimethanol, bisphenol A, bisphenol S, etc. An aromatic dihydroxy compound can be mentioned.

  Among these, terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid or their dimethyl ester compounds are used as dicarboxylic acid compounds, and ethylene glycol, 1,3-propanediol, 1,4-butane are used as dihydroxy compounds. Diol, polytetramethylene glycol, neopentyl glycol, and cyclohexanedimethanol can be preferably used.

  These polyesters may be used alone or in combination of two or more. When mixing two or more types, polyester polymers polymerized separately in advance may be blended and melted in the form of chips. It is good also as a structure, and you may mix and use it with a static mixer.

  Among these films made of polyester, in the present invention, a film having a melting point of 200 to 270 ° C., preferably 210 to 260 ° C., more preferably 220 to 250 ° C. is used. When the melting point is less than 200 ° C., since the heat resistance is poor, there is a possibility that fusion to the mold may occur during the molding process. Is unsuitable. When the melting point exceeds 270 ° C., the productivity is poor.

  The plane orientation coefficient of the polyester film used in the present invention is 0.05 to 0.11, preferably 0.06 to 0.11. If the plane orientation coefficient is less than 0.05, the strength of the film tends to be inferior and handling properties may be deteriorated. If the plane orientation coefficient exceeds 0.11, the deep drawing formability may be inferior. Not suitable as an interior material.

The apparent density of the polyester film is preferably 1300 to 1400 kg / m ³ , more preferably 1320 to 1395 kg / m ³ , and particularly preferably 1340 to 1390 kg / m ³ . If it is less than 1300 kg / m ³ , the heat resistance of the film is inferior, and fusion to the mold may occur during the molding process, which is not preferable. If it exceeds 1400 kg / m ³ , the crystallinity of the film becomes so high that the molding processability is lowered, which is not preferable.

  The polyester film satisfying these melting point, plane orientation count, and apparent density is obtained by, for example, polyethylene terephthalate obtained by copolymerizing the following copolymerization components in a total range of 25 mol% or less, preferably 20 mol% or less. Furthermore, it can obtain by extending | stretching, taking specific conditions as extending | stretching temperature at the time of extending | stretching, a draw ratio, and a drawing speed. The melting point of homopolyethylene terephthalate that does not copolymerize the copolymer component is about 270 ° C.

  As a copolymerization component of polyethylene terephthalate, for example, isophthalic acid or naphthalenedicarboxylic acid can be used as a dicarboxylic acid component, and for example, neopentylene glycol or cyclohexanedimethanol can be used as a diol component.

  The thickness of the polyester film is preferably 5 to 188 μm, more preferably 25 to 125 μm, from the viewpoints of economy, productivity, moldability, and the like.

  The polyester film may be subjected to, for example, corona discharge treatment from the viewpoint of adhesion to interior materials, particularly other materials constituting the ceiling material and laminate materials, and may be subjected to surface treatment by in-line coating or offline coating. .

[Fine particles]
The polyester film preferably contains fine particles in order to improve handleability and processability. The fine particles may be any of internally precipitated particles, inorganic particles, and organic particles. From the viewpoint of obtaining good handleability and processability without causing defects in the film, the average particle size of the fine particles is preferably 0.01 to 5 μm, and the content is preferably 0.01 to 1% by weight. .

  As the inorganic fine particles, for example, wet and dry silica, colloidal silica, aluminum silicate, alumina, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, aluminum oxide, mica, kaolin, and clay can be used. As the organic fine particles, for example, particles containing styrene, silicone, acrylic acid, methacrylic acid, polyester, divinyl compound as constituent components can be used. Of these, fine particles of wet and dry silica, aluminum silicate, alumina, styrene, silicone, acrylic acid, methacrylic acid, polyester, and divinylbenzene are preferable. Two or more kinds of these internally precipitated particles, inorganic particles, and organic particles may coexist.

[Production method]
The polyester film for automobile interior materials of the present invention can be produced, for example, by the following method.
The polyester chip to be used is dried for 7 hours at 130 ° C. in a nitrogen atmosphere or under vacuum, and is supplied to an extruder and melted. The resin melted in the extruder is subjected to removal of foreign matters and leveling of the amount of extrusion through a filter and a gear pump, and discharged and extruded in a sheet form from a T-die onto a cooling drum to obtain an unstretched sheet. At that time, a wire electrode, a tape-like electrode or a needle-like electrode is used to apply static electricity and adhere to the cooling drum, a casting method in which a water film is provided between the cooling drum and the extruded polymer sheet, and the cooling drum temperature. The sheet-like polymer is brought into close contact with the cooling drum by a method of adhering a polymer extruded from the glass transition point of polyester to (glass transition point-20 ° C.) or a combination of these methods.

  Next, the film is stretched in the longitudinal direction using an unstretched film and then stretched in the width direction, or the film is stretched in the width direction and then stretched in the longitudinal direction. Stretching is performed by the simultaneous biaxial stretching method that stretches simultaneously.

  The stretching ratio in the stretching is preferably 1.6 to 4.0 times, more preferably 2.4 to 3.8 times, and particularly preferably 2.8 to 3.5 times in each direction. The stretching speed is desirably 1000 to 200000% / min, and the stretching temperature is a temperature range from the glass transition point of the polyester to (glass transition point + 100 ° C.), preferably 80 to 170 ° C., particularly preferably longitudinal stretching. The temperature is 90 to 150 ° C., and the stretching temperature in the width direction is 100 to 150 ° C.

  In order to impart very excellent moldability to the film, it is particularly preferable that the stretching temperature in the longitudinal direction is 100 to 130 ° C., and in particular, it does not crystallize at a temperature of 100 ° C. or higher for about 1 to 100 seconds before longitudinal stretching. It is preferable to stretch after preheating in the range. If it does in this way, the outstanding flatness by uniform extending | stretching and the outstanding moldability by alignment spot suppression can be acquired.

  The film is heat-treated after biaxial stretching. This heat treatment can be performed by any conventionally known method such as in an oven or on a heated roll. The heat treatment temperature is usually in the range of the stretching temperature to the melting point of the raw material, preferably 100 to 230 ° C, more preferably 110 to 220 ° C, and particularly preferably 120 to 210 ° C. By setting the temperature within this range, a film excellent in molding processability and impact resistance can be obtained. On the other hand, if the heat treatment temperature is lower than this temperature, the heat resistance and dimensional stability may be undesirably deteriorated, and if it is high, the moldability may be unfavorably deteriorated. The heat treatment time is preferably 1 to 30 seconds. This heat treatment may be performed by relaxing the film in the longitudinal direction and / or the width direction. Thereafter, further corona discharge treatment can be performed. This corona treatment is preferable in terms of improving adhesiveness with other materials.

Hereinafter, the present invention will be described in more detail with reference to examples.
The physical properties of the polymer and film and the properties of the film and processed product were measured and evaluated by the following methods.

(1) Melting point (Tm) of polyester film
About 20 mg of polyester film was measured with a differential scanning calorimeter (Du Pont Instruments 910 DSC) at a heating rate of 20 ° C./min, and the endothermic peak temperature was defined as the melting point (Tm).

(2) Plane orientation coefficient Using sodium D-line (wavelength 589 nm) as a light source, a plane orientation coefficient Ns = obtained from refractive indexes (nMD, nTD, nZ, respectively) in the longitudinal direction, width direction, and thickness direction using an Abbe refractometer (NMD + nTD) / 2-nZ was calculated and obtained.

(3) Apparent density 10 cm × 10 cm taking the size of the sample, and measuring the thickness of the試科a micrometer, determine the volume of the sample, then measuring the weight of試科, calculate the weight per 1 m ³ did. The number of samples was five, and the average value was the apparent density.

(4) Formability Vacuum forming was performed using a headliner forming mold. First, a polyester film and a plate-shaped urethane foam for thermoforming (thickness 5 mm, specific gravity 0.035) were dry laminated by an ordinary method using an epoxy adhesive to prepare a two-layer structure. The resulting structure was heated so that the polyester film would be on the mold side and both edge portions were gripped with clips while the surface temperature was 170 ° C., and the depth of the concave curved portion was 1800 mm × 1400 mm wide. An automobile ceiling material having a thickness of 80 mm was formed. The appearance was evaluated by visually confirming that wrinkles and blisters did not occur and that the shape followed the shape of the mold, and the moldability was determined according to the following criteria.
○: The thickness of the ceiling material is uniform and the appearance is good.
Δ: The thickness of the ceiling material is uneven or part of the appearance is defective.
X: Some of the ceiling material has cracks or the whole does not follow the mold.

[Example 1]
Using a mixture of 87 parts by weight of dimethyl terephthalate, 13 parts by weight of dimethyl isophthalate, and 64 parts by weight of ethylene glycol, using tetrabutoxy titanium as a transesterification catalyst, germanium dioxide as a polymerization catalyst, orthophosphoric acid as a stabilizer, and further as a lubricant. Copolymerized polyethylene terephthalate having an intrinsic viscosity (o-chlorophenol, 35 ° C.) of 0.70 was added by a conventional method by adding true spherical silica having an average particle size of 1.5 μm to 0.1% by weight based on the polymer. I got a chip.

  This chip is dried at 160 ° C for 5 hours in a vacuum dryer, and after sufficiently removing moisture, it is supplied to a single screw extruder, melted, passed through a filter and a gear pump, and foreign matter is removed and the amount of extrusion is leveled. After that, the sheet was discharged in the form of a sheet on a cooling drum having a melting temperature of 275 ° C. and temperature controlled from a T die to 25 ° C. At that time, a wire-like electrode having a diameter of 0.08 mm was applied electrostatically and adhered to the cooling drum to obtain an unstretched film. Next, the unstretched sheet was stretched 2.8 times in the longitudinal direction at 115 ° C., then stretched 2.8 times in the transverse direction at 120 ° C., and further subjected to heat treatment at 190 ° C. for 7 seconds at a relaxation rate of 5%. Thus, a biaxially stretched polyester film having a thickness of 50 μm was obtained.

  The evaluation results of the obtained film are shown in Table 1. Moreover, when urethane film and dry lamination were performed using this film and moldability was evaluated, a uniform ceiling material thickness was obtained, and the appearance was also satisfactory.

[Example 2]
In the polymerization of the polyester of Example 1, 87 parts by weight of dimethyl terephthalate and 13 parts by weight of dimethyl isophthalate were changed to 100 parts by weight of dimethyl terephthalate, and 64 parts by weight of ethylene glycol was changed to 55 parts by weight of diethylene glycol and 16 parts by weight of neopentyl glycol. Extrusion, intrinsic viscosity (o-chlorophenol, 35) was changed in the same manner as in Example 1 except that bulk silica having an average particle size of 2.4 μm was added to the polymer in an amount of 0.05% by weight as a lubricant. ° C) 0.75 copolymer polyethylene terephthalate chip was obtained. Then, after obtaining an unstretched sheet in the same manner as in Example 1, the unstretched sheet was stretched 2.9 times in the longitudinal direction at 110 ° C., and then stretched 2.9 times in the transverse direction at 120 ° C. A heat treatment was performed at 6% at 120 ° C. for 5 seconds and wound up to obtain a biaxially stretched polyester film having a thickness of 75 μm.

  The evaluation results of the obtained film are shown in Table 1. Further, when a two-layer laminate was prepared using this film and the moldability was evaluated, a uniform ceiling material thickness was obtained, and the appearance was also satisfactory.

[Example 3]
Extrusion and intrinsic viscosity in the same manner as in Example 1 except that 87 parts by weight of dimethyl terephthalate and 13 parts by weight of dimethyl isophthalate were changed to 82 parts by weight of dimethyl terephthalate and 18 parts by weight of dimethyl isophthalate in the polymerization of the polyester of Example 1. A chip of copolymer polyethylene terephthalate (o-chlorophenol, 35 ° C.) 0.68 was obtained. Then, after obtaining an unstretched sheet in the same manner as in Example 1, the unstretched sheet was stretched 2.8 times in the longitudinal direction at 110 ° C., and then stretched 2.9 times in the transverse direction at 115 ° C. A heat treatment was performed at 5% at 155 ° C. for 4 seconds and wound up to obtain a biaxially stretched polyester film having a thickness of 50 μm.

  The evaluation results of the obtained film are shown in Table 1. Further, when a two-layer laminate was prepared using this film and the moldability was evaluated, a uniform ceiling material thickness was obtained, and the appearance was also satisfactory.

[Comparative Example 1]
In the polymerization of the polyester of Example 1, except that 87 parts by weight of dimethyl terephthalate and 13 parts by weight of dimethyl isophthalate were changed to 100 parts by weight of dimethyl terephthalate, extrusion, intrinsic viscosity (o-chlorophenol, 35 ° C., 35 ° C. ) 0.64 polyethylene terephthalate chips were obtained. Then, an unstretched sheet was obtained in the same manner as in Example 1, and the unstretched sheet was stretched 3.1 times in the longitudinal direction at 110 ° C. and further 3.2 times in the width direction at 120 ° C., and left at 210 ° C. for 4 seconds. The biaxially stretched polyester film having a thickness of 50 μm was obtained.

  The evaluation results of the obtained film are shown in Table 1. In addition, when a two-layer laminate was prepared using this film and the moldability was evaluated, the thickness of the ceiling material was uniform, but the whole did not follow the mold and the appearance was poor. Therefore, the film was inferior in formability.

[Comparative Example 2]
The unstretched polyester sheet of Example 1 was stretched 3.3 times in the longitudinal direction at 100 ° C., then stretched 3.3 times in the transverse direction at 115 ° C., and further heat treated at 195 ° C. for 6 seconds at a relaxation rate of 5%. And wound up to obtain a biaxially stretched polyester film having a thickness of 50 μm.

  The evaluation results of the obtained film are shown in Table 1. In addition, when a two-layer laminate was prepared using this film and formability was evaluated, the thickness of the ceiling material was partially uneven, and a portion that did not follow the mold was observed in appearance. Therefore, the film was inferior in formability.

  The polyester film for automobile interior materials according to the present invention has sufficient rigidity, is light and can be easily molded, and is particularly used as a structural member for automobile interior materials such as molded ceilings, columns, floors, instrument panels, and sheets. It can be preferably used as a core material. When used as a core material for a molded ceiling, for example, a film / urethane foam / nonwoven fabric layer of the present invention or a film / nonwoven fabric layer of the present invention is used to obtain a laminate by thermal lamination or dry lamination with an adhesive. By performing deep drawing with a metal mold, a molded ceiling can be obtained. In this molding, the conventional film can be processed so as to break without causing any defects. Therefore, when the film of the present invention is used, sufficient rigidity can be obtained without using a glass fiber mat, and it can be used as an automobile interior material excellent in environmental suitability.

  The polyester film for automobile interior materials of the present invention is useful for reducing environmental burdens, such as being able to produce automotive interior materials having excellent mechanical properties and light weight, and being easy to dispose and recycle.

Claims (2)

  A polyester film for automobile interior materials having a melting point of 200 to 270 ° C. and a plane orientation coefficient of 0.05 to 0.11. The polyester film for automobile interior materials according to claim 1, wherein the apparent density is 1300 to 1400 kg / m ³ .