Automotive ceiling materials

Abstract

The objective is to provide automotive ceiling materials that possess high rigidity at high temperatures and high recyclability. [Solution] An automobile ceiling material comprising a laminate in which a fibrous material / a first film / a porous body / a second film are laminated in this order, wherein both the first film and the second film are made of a polyester resin having a glass transition temperature of 90°C or higher, and both the fibrous material and the porous body are made of a thermoplastic resin.

Description

[Technical Field]

[0001] This invention relates to automotive ceiling materials. [Background technology]

[0002] In response to the growing social demand for a circular economy, the automotive industry is increasingly using recycled materials. Along with this, there is a growing need for easily recyclable automotive components, including interior and exterior materials.

[0003] In response to this need, material manufacturers are considering replacing existing difficult-to-recycle materials with easily recyclable materials. Regarding automotive ceiling materials, a type of interior material, efforts have been underway to replace glass fiber sheets, one of its constituent materials and therefore difficult to recycle, with easily recyclable resin-based materials.

[0004] Glass fiber sheets function as a reinforcing material in automotive ceiling materials, suppressing sagging caused by the weight of the ceiling material itself. Therefore, when considering a replacement, it is necessary to search for a material that has equivalent bending resistance characteristics, i.e., rigidity, to glass fiber sheets in the temperature range expected in the automotive interior.

[0005] When automobiles are exposed to direct sunlight during the summer, the temperature inside the vehicle can rise to around 80°C. Therefore, alternative resin materials are required to maintain their rigidity even at temperatures above 80°C. For this reason, Patent Document 1 discloses an invention in which a glass fiber sheet is replaced with a polyester resin sheet that has been made heat-resistant and high-strengthened by promoting crystallization using a crystal nucleating agent. Furthermore, Patent Document 2 focuses on the fact that uniaxially oriented films exhibit high strength against deformation in the stretching direction and show heat resistance. It discloses an invention in which a glass fiber sheet is replaced with a material in which multiple polyester resin films that have been made high-strengthened by uniaxial stretching are laminated and integrated so that the stretching directions of adjacent films are different. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-214293 [Patent Document 2] Japanese Patent Publication No. 2008-254557 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, both inventions in Patent Documents 1 and 2 use a material made of polyethylene terephthalate as a substitute for glass fiber sheets, and due to the resin properties, the glass transition temperature is at most about 80°C. Therefore, there is still a problem of insufficient rigidity when considering the high temperature inside a vehicle.

[0008] Therefore, in view of these problems, the present invention aims to provide an automobile ceiling material that provides high rigidity at high temperatures and easy recyclability (i.e., excellent recyclability) by replacing the glass fiber sheet with a film made of polyester resin having a glass transition temperature of 90°C or higher. [Means for solving the problem]

[0009] To solve the aforementioned problems, the present invention provides an automobile ceiling material that employs the following configuration. (1) An automobile ceiling material comprising a laminate in which a fiber material / first film / porous body / second film are laminated in this order, wherein both the first film and the second film are made of a polyester resin having a glass transition temperature of 90°C or higher, and both the fiber material and the porous body are made of a thermoplastic resin, characterized in that (2) The first film and the second film are characterized in that the polyester resin contains an isosorbide component as a glycol component constituting the polyester resin, and the isosorbide component is contained in an amount of 30 mol% to 60 mol% of the total glycol component, as described in (1). (3) The automobile ceiling material according to (2), characterized in that both the fibrous material and the porous body are made of polyester resin. [Effects of the Invention]

[0010] According to the present invention, by replacing the glass fiber sheet with a film made of polyester resin having a glass transition temperature of 90°C or higher, high rigidity at high temperatures can be achieved. Furthermore, since the fiber material, the first film, the porous body, and the second film are all made of thermoplastic resin, an automotive ceiling material with easy recyclability (i.e., excellent recyclability) can be provided. [Brief explanation of the drawing]

[0011] [Figure 1] This is a conceptual diagram illustrating a method for evaluating the rigidity of a laminated material, modeled after automotive ceiling material, at 80°C. [Modes for carrying out the invention]

[0012] The automotive ceiling material of the present invention will be described in detail below. The automotive ceiling material of the present invention includes a laminate in which a fiber material / first film / porous body / second film are laminated in this order. Furthermore, both the first film and the second film are made of polyester resin having a glass transition temperature of 90°C or higher. Here, "the film is made of polyester resin having a glass transition temperature of 90°C or higher" means "the film is made only of polyester resin having a glass transition temperature of 90°C or higher," but it may also contain components other than polyester resin having a glass transition temperature of 90°C or higher as long as it does not impair the effects of the present invention. Specifically, it is preferable that the film contains 95% by mass or more of polyester resin having a glass transition temperature of 90°C or higher, more preferably 98% by mass or more, and even more preferably 99% by mass or more of polyester resin with a glass transition temperature of 90°C or higher relative to the total components constituting the film. Because the film (first film and second film) is made of polyester resin, the used automotive ceiling material can be crushed and re-pelletized, or returned to monomer units by chemical recycling methods, and reused again as a raw material for fiber material, film, or porous body. Furthermore, because the above-mentioned polyester resin has a glass transition temperature of 90°C or higher, the film maintains high rigidity even in a high-temperature atmosphere of 80°C, exhibiting high resistance to forces applied perpendicular to the plane of the film, and thus enabling high rigidity even in automotive ceiling materials. Note that "the fiber material, etc., is made of thermoplastic resin" means "the fiber material, etc., is made of thermoplastic resin only," but it may contain components other than thermoplastic resin as long as it does not impair the effects of the present invention. Specifically, it is preferable that the fiber material, etc., contains 95% by mass or more of thermoplastic resin, more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0013] <First film and second film> The automotive ceiling material of the present invention has a first film and a second film as reinforcing materials. First, the first film will be described. The first film of the automotive ceiling material of the present invention is made of a polyester resin having a glass transition temperature of 90°C or higher. Examples of polyester resins having a glass transition temperature of 90°C or higher include those containing a terephthalic acid component as a dicarboxylic acid component constituting the polyester resin, and a bulky glycol component in combination with an ethylene glycol component as the glycol component. Specific examples of bulky glycol components include a spiroglycol component, an isosorbide component, and a 2,2,4,4-tetramethyl-1,3-cyclobutanediol component. Among these, the isosorbide component is preferred because it can be easily obtained, for example, by hydrogenating D-glucose and undergoing a dehydration reaction, thus having a low environmental impact.

[0014] From the viewpoint of achieving a glass transition temperature of 90°C or higher for the polyester resin, the preferred content of the isosorbide component in the glycol component of the polyester resin is preferably 5 mol% or more when the total glycol component is 100 mol%. If the isosorbide component content is less than 5 mol%, the glass transition temperature will be less than 90°C, and the rigidity in a high-temperature atmosphere of 80°C may be insufficient. From the viewpoint of improving the glass transition temperature of the film and increasing its rigidity in an 80°C atmosphere, a higher isosorbide component content is preferable. Furthermore, increasing the isosorbide component content causes a decrease in the crystallinity of the polyester resin, and when the first film is heated above its glass transition temperature, it exhibits thermal fusion properties to other materials. As a result, it can be layered and integrated with other materials constituting the ceiling material without the use of adhesives. Thus, from the viewpoint of achieving both rigidity in an 80°C atmosphere and thermal fusion properties, the isosorbide component content is more preferably 30 mol% or more when the total glycol component is 100 mol%. Conversely, the preferred upper limit for the isosorbide component content is preferably 60 mol% from the viewpoint of polymerizability during resin production, and more preferably 50 mol% or less from the viewpoint of cost.

[0015] As a glycol component, the polyester resin may optionally contain other glycol components in addition to the ethylene glycol component and the isosorbide component. The other glycol components are not particularly limited as long as they do not affect the glass transition temperature mentioned above; for example, from the viewpoint of improving impact resistance, 1,4-cyclohexanedimethanol component may be mentioned.

[0016] Further, the higher the glass transition temperature of the polyester resin, the more it can enhance rigidity under a high-temperature environment of 80°C. From this viewpoint, the glass transition temperature of the polyester resin is preferably 100°C or higher, more preferably 115°C or higher.

[0017] In the present invention, both the first film and the second film are made of a polyester resin having a glass transition temperature of 90°C or higher. For example, when the glass transition temperature of the polyester resin constituting these films is 100°C, the glass transition temperature of these films is also 100°C.

[0018] The polyester resin constituting the second film of the automobile ceiling material of the present invention has the same glass transition temperature as the polyester resin constituting the first film. Therefore, the glass transition temperature of the polyester resin constituting the second film is 90°C or higher, preferably 100°C or higher, and more preferably 115°C or higher from the viewpoint of achieving high-temperature rigidity equivalent to that of a glass fiber sheet.

[0019] From the viewpoint of molding into the shape of an automobile ceiling, the first film and the second film provided in the automobile ceiling material of the present invention are preferably unstretched films. Being unstretched allows easy molding with low stress by heating to a temperature equal to or higher than the glass transition temperature.

[0020] The basis weight of the first film and the second film provided in the automobile ceiling material of the present invention (weight per 1 2 square meter) is 100 to 350 g / 2It is preferable that the basis weight be 100 g / m². 2 As a result of the above, the film gains rigidity, and when the automotive ceiling material of the present invention is installed in the ceiling of a vehicle, sagging due to its own weight can be suppressed. 2 By doing the following, a lightweight automotive ceiling material can be created. From the viewpoint of achieving both sagging suppression and lightness, the basis weight of the first and second films should be 150-300 g / m². 2 It is more preferable that this is the case. Here, the basis weight of the first film and the basis weight of the second film may be the same or different.

[0021] Here, the description of the second film provided in the automobile ceiling material of the present invention is the same as the description of the first film above, so it will be omitted.

[0022] The first film and the second film described above may be the same or different. From the viewpoint of achieving better productivity of the automotive ceiling material of the present invention, it is preferable that the first film and the second film are the same. <Porous material> The automotive ceiling material of the present invention has a porous body as an insulating material.

[0023] Furthermore, the porous body, like the fibrous material described later, is made of a thermoplastic resin from the viewpoint of recyclability. From the viewpoint of achieving even better recyclability, it is preferable that both the porous body and the fibrous material described later be made of polyester resin. In other words, by unifying the materials constituting the automobile ceiling material to a single type, polyester resin, the recyclability can be further improved. From the viewpoint of versatility, polyethylene terephthalate is particularly preferred as the type of polyester resin constituting the porous body.

[0024] Furthermore, the porous material of the automotive ceiling material of the present invention functions as an insulating layer in the automotive ceiling material. Therefore, this porous material has a thermal resistance of 0.1 m 2It is preferable that the power output is kW or higher.

[0025] The specific form of the porous body in the automotive ceiling material of the present invention may be any of foam, woven fabric, or nonwoven fabric, but as described above, the thermal resistance is 0.1 m 2 It is preferable that the power output is kW or higher. <Textile materials> The automotive ceiling material of the present invention has a fibrous material as its surface material.

[0026] Furthermore, the fibrous material of the automobile ceiling material of the present invention, like the film (specifically, the first film and the second film) and the porous body, is made of a thermoplastic resin from the viewpoint of recyclability, and is preferably made of polyester resin. In particular, polyethylene terephthalate is preferred as the type of polyester resin constituting the fibrous material, from the viewpoint of further improving recyclability by unifying the materials constituting the automobile ceiling material to a single material.

[0027] Furthermore, as for the specific form of the fibrous material incorporated in the automobile ceiling material of the present invention, since it is placed on the outermost surface on the inside of the automobile ceiling material, a smooth texture is required, and from this viewpoint, it is preferable that it be a woven fabric, a knitted fabric, or a nonwoven fabric. [Examples]

[0028] The present invention will be described in more detail below using examples. The method for measuring the characteristic values ​​shown in the examples is as follows.

[0029] A. Glass transition temperature A differential scanning calorimeter (Seiko Electronics Co., Ltd., RDC220) was used to perform DSC measurements and analysis in accordance with JIS K7121-1987 and JIS K7122-1987. Under the measurement conditions, a 5 mg sample was heated from 0°C to 280°C at a heating rate of 20°C / min in a nitrogen atmosphere. The glass transition temperature of the resin was determined from the sigmoid baseline change observed in the region from 50°C to 140°C.

[0030] B. Basis Weight Ten 10 cm square test pieces are cut out from a film or glass fiber sheet, the ten test pieces are stacked and their weight is measured, and the value obtained by multiplying the resulting weight by 10 is taken as the basis weight of the film (g / m 2 ).

[0031] C. Content of Isosorbide Component in Polyester Resin The composition and content of diol components were determined from 1H-NMR measurement and 13C-NMR measurement using a nuclear magnetic resonance apparatus (NMR). Specifically, a sample was dissolved in a deuterated chloroform solvent added with trifluoroacetic acid, 1H-NMR measurement and 13C-NMR measurement were performed using "AL-400" manufactured by JEOL Ltd., each diol component was identified from the chemical shift and integrated value of the obtained peaks, and the abundance ratio (molar ratio) thereof was calculated, to determine the content (mol%) of the isosorbide component relative to 100 mol% of all diol components.

[0032] D. Thermal Resistance of Porous Body Thermal conductivity was measured in accordance with JIS A 1412-2(1999) 6.2, and the obtained thermal conductivity was multiplied by the thickness to obtain thermal resistance. Specifically, a 30 cm square test piece cut out from a porous body was set in a thermal conductivity measuring apparatus HC-074 (manufactured by Eiko Seiki Co., Ltd.), measurement was performed under the conditions of a plate temperature difference of 25°C and an average temperature of 20°C (high plate temperature: 32.5°C, low plate temperature: 7.5°C), and the thermal conductivity (W / m·K) was calculated from the average value of three measurements. This thermal conductivity is multiplied by the thickness obtained in the measurement process to obtain thermal resistance (m 2 ·K / W).

[0033] E. Stiffness of Laminate at 80°C The stiffness of the laminate at 80°C was measured as shown in Figure 1. Figure 1 is a conceptual diagram showing the evaluation method for the stiffness of a laminate simulating automobile ceiling material at 80°C. Specifically, a 10cm wide x 10cm long region at one end of a laminate (indicated by reference numeral 1), measuring 10cm wide x 30cm long, was fixed to a support column (30cm (width) x 30cm (length) x 20cm (height)) (indicated by reference numeral 2) with double-sided tape, so that the remaining 10cm wide x 20cm long region not fixed to the column protruded from the column. In this state, the laminate and column were held in an 80°C oven for 1 hour, and the stiffness at 80°C was evaluated from the change in height of the protruding end between the start of holding and after 1 hour. In this evaluation, a smaller change in height was judged to indicate better stiffness, and a change of more than 10mm was judged to be impractical.

[0034] [Example 1] A polyester resin raw material containing 24 mol% isosorbide, as listed in Table 1, was fed into a vented extruder (1). The material was extruded in a sheet form from a T-die while melting and kneading at 270°C. The sheet was then discharged between a pair of casting drums and polishing rolls cooled to 40°C, where it was allowed to adhere to the casting drums and cool and solidify to obtain the film shown in Table 1. Subsequently, two pieces of this film, measuring 10 cm wide x 30 cm long, were prepared and designated as the first and second films. Using a 10 cm wide x 30 cm long polyethylene terephthalate woven fabric (fiber material) prepared separately as a surface material for automobile ceiling materials, and a 10 cm wide x 30 cm long polyethylene terephthalate foam (porous material) prepared as an insulating material, the layers were stacked in the order of polyethylene terephthalate woven fabric / first film / polyethylene terephthalate foam / second film. Finally, the layers were pressed together at 150°C, above the glass transition temperature of the film, under a pressure of 0.5 MPa to create a laminate that mimicked automobile ceiling materials. Table 1 shows the detailed structure and evaluation results of the laminate in this example. In the laminate of Example 1, both the first film and the second film contained 100% by mass of polyester resin with a glass transition temperature of 90°C or higher relative to all constituent components.

[0035] [Comparative Example 1] Except for using a polyester resin raw material in which the diol component was 100 mol% ethylene glycol and no isosorbide component, a film was obtained in the same manner as in Example 1, and a laminate of polyethylene terephthalate fabric (fiber material) and polyethylene terephthalate foam (porous material) was prepared. In this bonding process, since the polyethylene terephthalate film does not exhibit heat-sealing properties even when heated, 3M's styrene-butadiene rubber-based spray adhesive "Spray Adhesive 99" was applied to each interface at a rate of 3 g / m². 2 The laminate was applied and bonded. Table 2 shows the detailed structure and evaluation results of the laminate in Comparative Example 1. Both the first and second films in this laminate did not contain polyester resin with a glass transition temperature of 90°C or higher.

[0036] [Comparative Example 2] In Comparative Example 1, instead of two films (the first film and the second film), a basis weight of 150 g / m² was used. 2 A laminate of two glass fiber sheets, polyethylene terephthalate fabric, and polyethylene terephthalate foam was prepared in the same manner as in Example 1, except that a glass fiber sheet was used. Table 2 shows the detailed composition and evaluation results of the laminate of Comparative Example 2. Note that the laminate of Comparative Example 2 had poor recyclability because it contained a glass fiber sheet.

[0037] [Example 2] Except for using a polyester resin raw material with an isosorbide component content of 18 mol% in the diol component, a film was obtained in the same manner as in Example 1, and a laminate was prepared of the two films, polyethylene terephthalate fabric, and polyethylene terephthalate foam. The details of the composition of the laminate in this example and the evaluation results are shown in Table 1. In the laminate of Example 2, both the first film and the second film contained 100% by mass of polyester resin with a glass transition temperature of 90°C or higher relative to all constituent components.

[0038] [Example 3] Except for using a polyester resin raw material with an isosorbide component content of 32 mol% in the diol component, a film was obtained in the same manner as in Example 1, and a laminate was prepared of the two films, polyethylene terephthalate fabric, and polyethylene terephthalate foam. The details of the composition of the laminate in this example and the evaluation results are shown in Table 1. In the laminate of Example 3, both the first film and the second film contained 100% by mass of polyester resin with a glass transition temperature of 90°C or higher relative to all constituent components.

[0039] [Example 4] Except for using a polyester resin raw material with an isosorbide component content of 44 mol% in the diol component, a film was obtained in the same manner as in Example 1, and a laminate was prepared of the two films, polyethylene terephthalate fabric, and polyethylene terephthalate foam. The details of the composition of the laminate in this example and the evaluation results are shown in Table 1. In the laminate of Example 4, both the first film and the second film contained 100% by mass of polyester resin with a glass transition temperature of 90°C or higher relative to all constituent components.

[0040] [Example 5] Except for using a polyester resin raw material with an isosorbide component content of 7 mol% in the diol component, a film was obtained in the same manner as in Example 1, and a laminate was prepared of the two films, polyethylene terephthalate fabric, and polyethylene terephthalate foam. The details of the composition of the laminate in this example and the evaluation results are shown in Table 2. In the laminate of Example 5, both the first film example and the second film contained 100% by mass of polyester resin with a glass transition temperature of 90°C or higher relative to all constituent components.

[0041] [Table 1]

[0042] [Table 2] [Industrial applicability]

[0043] The automotive ceiling material of the present invention is easily recyclable and can be used as an automotive ceiling material in various forms of mobility such as automobiles, trains, buses, and ships. [Explanation of symbols]

[0044] 1. A laminated structure that mimics the ceiling material of an automobile. 2 pillars

Claims

1. An automobile ceiling material comprising a laminate in which a fibrous material, a first film, a porous body, and a second film are laminated in this order, wherein both the first film and the second film are made of a polyester resin having a glass transition temperature of 90°C or higher, and both the fibrous material and the porous body are made of a thermoplastic resin.

2. The automobile ceiling material according to claim 1, characterized in that the polyester resin of the first film and the second film contains an isosorbide component as a glycol component constituting the polyester resin, and the isosorbide component is contained in an amount of 30 mol% to 60 mol% with respect to 100 mol% of the total glycol component.

3. The automobile ceiling material according to claim 2, characterized in that both the fibrous material and the porous body are made of polyester resin.

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