Car floor mat sheets

Abstract

To provide a sheet for automotive floor mats that has impact resistance and heat-sealing properties. [Solution] A polyester sheet for automotive floor mats, characterized by having copolymer polyester as the main component, containing polybutylene terephthalate, and exhibiting a melting enthalpy derived from polybutylene terephthalate of 5.0 to 20.0 J / g observed at around 225°C in DSC measurements.

Description

【Technical Field】 【0001】 The present invention relates to a sheet having impact resistance and heat fusion properties suitable for use as an automotive floor mat. 【Background Art】 【0002】 In response to the growing social demand for circular economy, the application of recycled materials in the automotive industry has been active. At the same time, there is also an increasing need for easy recyclability of automotive component materials, including interior and exterior materials. 【0003】 In response to this need, each material manufacturer has been increasing its efforts to replace difficult-to-recycle materials with easy-to-recycle materials. For example, Patent Document 1 discloses an invention in which glass fiber, a difficult-to-recycle material among the materials constituting an automotive ceiling material, is replaced with polyester, which is easy to recycle. Patent Document 2 also discloses an invention in which polyethylene in an automotive ceiling material is replaced with polyester, which is also easy to recycle. 【0004】 Here, as disclosed in Patent Document 3, polyethylene is used as a low-temperature heat-fusion sheet or a sound insulation sheet in addition to the ceiling material in automotive floor mats. 【Prior Art Documents】 【Patent Documents】 【0005】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2008-254557 【Patent Document 2】 Japanese Patent Application Laid-Open No. 2004-25522 【Patent Document 3】 Japanese Patent Application Laid-Open No. 10-109582 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0006】 As mentioned above, polyethylene sheets are also used in floor mats, but when considering easy recycling, it is preferable to replace the polyethylene sheets in floor mats with polyester sheets such as polyethylene terephthalate or polybutylene terephthalate. Furthermore, the polyester used in this case should be one whose melting point has been lowered by copolymerization so that it can be used as a low-temperature heat-sealable material, just like polyethylene. 【0007】 However, polyesters whose melting point has been lowered by copolymerization (hereinafter sometimes referred to as copolymerized polyesters) have inferior impact resistance compared to polyethylene. Therefore, when copolymerized polyester sheets are used instead of polyethylene, there is a problem that the sheets may break due to impacts applied to them during use. 【0008】 Therefore, in view of these problems, the present invention aims to provide an automobile floor mat sheet (hereinafter sometimes simply referred to as "sheet") that has impact resistance and heat-sealing properties. [Means for solving the problem] 【0009】 To solve the aforementioned problems, the present invention provides a polyester sheet for automotive floor mats that employs the following configuration. (1) A sheet for automotive floor mats, characterized in that it mainly consists of copolymerized polyester, contains polybutylene terephthalate, and the melting enthalpy derived from polybutylene terephthalate observed at around 225°C in DSC measurement is 5.0 to 20.0 J / g. (2) The sheet for automobile floor mats according to (1), characterized in that it contains an infrared absorbent. [Effects of the Invention] 【0010】 According to the present invention, it is possible to provide a sheet for automotive floor mats that has impact resistance and heat-sealing properties. [Modes for carrying out the invention] 【0011】 The automotive floor mat sheet of the present invention will be described in detail below. The polyester sheet for automotive floor mats of the present invention mainly consists of copolymerized polyester and contains polybutylene terephthalate, and the enthalpy of melting derived from polybutylene terephthalate observed at around 225°C in DSC measurement is 5.0 to 20.0 J / g. The enthalpy of melting derived from polybutylene terephthalate observed at around 225°C in DSC measurement is 5.0 J / g or higher, which provides sufficient impact resistance for use as an automotive floor mat. Furthermore, the enthalpy of melting derived from polybutylene terephthalate observed at around 225°C in DSC measurement is 20.0 J / g or lower, which allows for sufficient thermal fusion even at low temperatures of 200°C or lower, thus suppressing thermal deformation of the material being joined when joining it with other materials during the floor mat manufacturing process. Here, the main component refers to the component that accounts for more than 50% by mass when the total amount of resin components constituting the sheet of the present invention is taken as 100% by mass. 【0012】 <Copolymerized polyester> The copolymerized polyester used in the sheet of the present invention refers to a material in which the main component of the dicarboxylic acid is terephthalic acid, and its copolymerization components include, for example, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, sebacic acid, and other components other than terephthalic acid, and the main component of the diol is ethylene glycol, and its copolymerization components include, for example, diethylene glycol, propylene glycol, 1,4-cyclohexanedimethanol, neopentyl glycol, and other components other than ethylene glycol. Here, the main component refers to a component that exceeds 50 mol% when the total amount of the dicarboxylic acid component or glycol component constituting the copolymerized polyester is taken as 100 mol%. 【0013】 Furthermore, the copolymer polyester content in the sheet of the present invention exceeds 50% by mass when the total amount of resin components constituting the sheet is set to 100% by mass, from the viewpoint of achieving high heat-sealability of the sheet as described later. However, since copolymer polyester is a brittle material, it is necessary to impart impact resistance by including other components such as polybutylene terephthalate, as described later. From this viewpoint, the copolymer polyester content in the sheet is preferably 60 to 95% by mass, and more preferably 70 to 90% by mass. 【0014】 From the viewpoint of enabling the sheet of the present invention to exhibit high heat-sealability at temperatures of 200°C or lower, the melting point of the copolymerized polyester is preferably 150°C or lower, and more preferably 140°C or lower. 【0015】 <Polybutylene terephthalate> The sheet of the present invention contains polybutylene terephthalate from the viewpoint of imparting impact resistance. The polybutylene terephthalate content is preferably 5% by mass or more and less than 50% by mass when the total amount of resin components constituting the sheet of the present invention is 100% by mass, with the melting enthalpy derived from polybutylene terephthalate observed at around 225°C in DSC measurement of the sheet being 5.0 to 20.0 J / g, from the viewpoint of achieving both impact resistance and heat sealability. A more preferable content is 10 to 30% by mass. 【0016】 In this invention, polybutylene terephthalate primarily consists of terephthalic acid as the dicarboxylic acid component and butanediol as the diol component. However, it may also contain small amounts of other dicarboxylic acid components or diol components, as long as it does not impair the effects of this invention. 【0017】 <Enthalpy of melting of the sheet> From the viewpoint of achieving both impact resistance and thermal fusion properties, the sheet of the present invention has a melting enthalpy derived from polybutylene terephthalate, observed at around 225°C in DSC measurements, of 5.0 to 20.0 J / g. If the melting enthalpy exceeds 20.0 J / g, it becomes necessary to melt the polybutylene terephthalate crystals when joining the sheet of the present invention to other materials. Melting the polybutylene terephthalate crystals requires a temperature of 225°C or higher, in which case the materials to be joined will undergo thermal deformation. On the other hand, if the melting enthalpy is less than 5.0 J / g, the polybutylene terephthalate content is too low, and sufficient impact resistance cannot be obtained. From this viewpoint, the melting enthalpy of the sheet is preferably 10.0 to 15.0 J / g. 【0018】 <Sheet thickness> The sheet of the present invention preferably has a thickness of 50 to 500 μm. If the thickness is less than 50 μm, sufficient sound insulation performance may not be obtained when used as a sound insulation sheet. Also, if the thickness is greater than 500 μm, the moldability when forming a floor mat shape may be insufficient. From this viewpoint, the sheet of the present invention is more preferably 100 to 300 μm thick. 【0019】 <Infrared absorbing material> When performing molding on the floor mat using the sheet of the present invention after preheating it with an infrared heater, it is preferable to contain an infrared absorber from the viewpoint of enhancing the temperature rise effect by infrared irradiation and increasing the molding cycle. Examples of the infrared absorber that can be suitably used in the sheet of the present invention include infrared absorbing dyes such as cyanine-based dyes, phthalocyanine-based dyes, polymethine-based dyes, squarylium-based dyes, porphyrin-based dyes, metal dithiol complex-based dyes, and diimonium-based dyes, carbon materials having a graphite structure such as carbon black, graphene, fullerene, and carbon nanotubes, and inorganic compounds such as magnesium carbonate, magnesium silicate, silicon dioxide, aluminum oxide, barium sulfate, calcium sulfate, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, phosphates, silicates, hydrotalcites, tin-based metal oxides, tungsten-based metal oxides, and hexaborides. Among them, from the viewpoints of easy availability, dispersibility in polyester-based resins, and absorption ability, etc., it is preferable that the infrared absorber is a carbon material, and more preferably carbon black. 【0020】 When the total amount of the resin components constituting the sheet is 100% by mass, the content of the infrared absorber in the sheet of the present invention is preferably 0.1 part by mass or more and 5.0 parts by mass or less. If the content of the infrared absorber is less than 0.1 part by mass, a sufficient temperature rise effect may not be obtained. Also, if it is more than 5.0 parts by mass, the recyclability may be impaired. 【Examples】 【0021】 The present invention will be described more specifically below using examples. The measurement methods of the characteristic values shown in the examples are as follows. 【0022】 A. Thickness of the sheet A dial gauge thickness gauge (JIS B7503 (1997), PEACOCK UPRIGHT DIAL GAUGE (0.001 × 2 mm), No. 25, 5 mmφ flat probe) was used to measure 10 arbitrarily selected points on the sample, and the average value was taken as the sheet thickness (μm). 【0023】 B. Melting point of polyester raw materials The melting point (°C) of the sample was defined as the melting peak observed when the sample was heated from 20°C to 300°C at a heating rate of 20°C / min using a differential scanning calorimetry analyzer (DSCII type, manufactured by Seiko Instruments Co., Ltd.). If multiple melting peaks were observed, the peak showing the highest temperature was used as the melting point. 【0024】 C. Enthalpy of fusion derived from polybutylene terephthalate in the sheet Using a differential scanning calorimetry analyzer (DSCII model, manufactured by Seiko Instruments Co., Ltd.), the melting peak observed around 225°C when the temperature was increased from 20°C to 300°C at a heating rate of 20°C / min was identified as the melting peak originating from polybutylene terephthalate. The flat areas before and after the peak were taken as the baseline, and the enthalpy of fusion (J / g) was calculated from the peak area and the weight of the sample used for measurement. 【0025】 D. Charpy impact test of the sheet The sheet was cut to a size of 50 mm x 10 mm, and the longer side (50 mm) of the sample was fixed to a Charpy impact tester manufactured by Toyo Seiki Seisakusho (capacity: 10 kg·cm, hammer weight: 1.019 kg, hammer lift angle: 127 degrees, distance from axis to center of gravity: 6.12 cm), and measurements were taken in an atmosphere of 23°C and 60% relative humidity. Ten tests were performed, and the average value of these tests was divided by the cross-sectional area of ​​the sample (sample thickness × 10 mm) to determine the Charpy impact strength (MJ / m²) of the sample. 2 This was used as an indicator of impact resistance. E. Thermal fusion test of the sheet Using a 7P-701S HEATSEAL TESTER manufactured by TESTER SANGYO.CO.LTD, two films were stacked and heat-sealed under the conditions of 170°C, 0.2 MPa pressure, and 1 sec pressurization time. A 25 mm wide sample was taken, and the strength was determined as the heat seal strength (N / 25 mm) when peeled using a Toyo Baldwin Tensilon at a peeling speed of 200 mm / min and a peeling angle of 90°. Films showing a high heat seal strength were judged to have good heat sealability. If the heat seal strength was greater than 10 N / 25 mm, and the strength was too high causing the sheet to tear during measurement, it was noted as unmeasurable, and it was judged to have sufficient heat sealability. 【0026】 [Example 1] A vented extruder was used to extrude a sheet of pre-vacuum-dried copolymer polyester (melting point: 110°C, containing isophthalic acid and diethylene glycol as copolymer components) and pre-vacuum-dried polybutylene terephthalate (melting point: 225°C) in a weight ratio of 80 / 20. The mixture was extruded from a T-die nozzle while degassing the vacuum vent section and melt-kneading at 250°C. The extruded sheet was then electrostatically pressed onto a casting drum cooled to 20°C using a needle-shaped edge pinning device, employing both electrostatic application and air chamber methods, and cooled and solidified to obtain the sheet. The physical properties of the obtained sheet are shown in Table 1. 【0027】 [Example 2] A sheet was obtained in the same manner as in Example 1, except that the weight ratio of copolymerized polyester to polybutylene terephthalate was 90 / 10. The physical properties of the obtained sheet are shown in Table 1. 【0028】 [Example 3] A sheet was obtained in the same manner as in Example 1, except that the weight ratio of copolymerized polyester to polybutylene terephthalate was 60 / 40. The physical properties of the obtained sheet are shown in Table 1. 【0029】 [Example 4] A sheet was obtained in the same manner as in Example 1, except that 0.5 parts by mass of carbon black was added as an infrared absorber to a total of 100 parts by mass of copolymerized polyester and polybutylene terephthalate. The physical properties of the obtained sheet are shown in Table 1. 【0030】 [Comparative Example 1] A sheet was obtained in the same manner as in Example 1, except that only copolymerized polyester was added. The physical properties of the obtained sheet are shown in Table 1. 【0031】 [Comparative Example 2] A sheet was obtained in the same manner as in Example 1, except that the weight ratio of copolymerized polyester to polybutylene terephthalate was 50 / 50. The physical properties of the obtained sheet are shown in Table 1. 【0032】 [Example 4] A sheet was obtained in the same manner as in Example 1, except that 0.5 parts by mass of carbon black was added as an infrared absorber to a total of 100 parts by mass of copolymerized polyester and polybutylene terephthalate. The physical properties of the obtained sheet are shown in Table 1. 【0033】 Furthermore, to verify the heating-promoting effect of carbon black when the sheet is heated by infrared irradiation, the sheet was placed 20 cm away from an infrared heater heated to 600°C and heated. The temperature of the sheet surface was monitored using an infrared radiation thermometer placed 30 cm away from the sheet, and the time it took to reach 170°C after setting was measured. As a result, the sheet in Example 1 required 8 seconds, while the sheet in Example 4 required only 4 seconds, confirming the heating-promoting effect of carbon black. 【0034】 [Table 1] [Industrial applicability] 【0035】 The automotive floor mat sheet of the present invention has impact resistance and heat-sealing properties, and can be used as an easily recyclable automotive floor mat by bonding it with other polyester materials and integrating it.

Claims

[Claim 1] A sheet for automotive floor mats, characterized in that it is mainly composed of copolymerized polyester, contains polybutylene terephthalate, and has a melting enthalpy derived from polybutylene terephthalate observed at around 225°C in DSC measurement of 5.0 to 20.0 J / g. [Claim 2] The sheet according to claim 1, characterized by containing an infrared absorbent.

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