Laminate

Abstract

To provide a laminate which facilitates recycling while having sufficient peeling strength, and is composed of a polyester-based material.SOLUTION: A laminate includes a first base material formed of polyester, a second base material formed of polyester, and a resin layer for bonding the first base material and the second base material, wherein the resin layer is formed of a polyester-based hot-melt adhesive containing polyester, and melt viscosity at 180°C of the polyester-based hot-melt adhesive is 30,000 mPa s or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a laminate.

Background Art

[0002] Since polyester has excellent performance, it has been conventionally used in various applications. Further, depending on the application, a layer containing polyester may be laminated and used.

[0003] For example, Patent Document 1 discloses a laminate including a sealant film containing a base polyester resin and a polyester elastomer resin that is incompatible with the base polyester resin, and a base material layer mainly composed of an ethylene terephthalate unit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Due to the influence of recent environmental problems, improvement of the recycling rate of materials has been demanded. However, it is difficult to recycle composite materials composed of different materials. For example, in Patent Document 1, a urethane-based adhesive is used as an adhesive layer. When recycling a composite material in which a layer made of a polyester component and a layer made of a polyurethane component are laminated, the polyurethane component may thermally decompose during heat treatment, and the thermally decomposed polyurethane residue or the like may contaminate the polyester component, making it difficult to recover the polyester component.

[0006] Therefore, an object of the present invention is to provide a laminate composed of a polyester-based material that has sufficient peel strength and is easy to recycle.

Means for Solving the Problem

[0007] The inventors of the present invention have conducted intensive studies and found that the above problems can be solved by using a specific adhesive layer. That is, the present invention is as follows.

[0008] One form of the present invention is a laminate. The laminate includes a first base material formed of polyester, a second base material formed of polyester, and a resin layer that bonds the first base material and the second base material. The resin layer is formed of a polyester-based hot melt adhesive containing polyester. The melt viscosity of the polyester-based hot melt adhesive at 180°C is 40,000 mPa·s or less.

[0009] The resin layer preferably has a mesh structure. The melting point of the polyester-based hot melt adhesive is preferably 170°C or less. The weight average molecular weight of the polyester contained in the polyester-based hot melt adhesive is preferably 50,000 or less.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a laminate composed of a polyester-based material that has sufficient peel strength and is easy to recycle.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0012] In this specification, when an upper limit value and a lower limit value are separately described, it is considered that a numerical range combining any upper limit value and any lower limit value is substantially disclosed.

[0013] In this specification, when a certain compound is described, its isomers are also considered to be described simultaneously.

[0014] In this specification, unless otherwise specified, various measurements are carried out with the environmental temperature being room temperature (25°C).

[0015] Hereinafter, the structure, manufacturing method, uses, etc. of the laminate will be described, but the present invention is not limited thereto.

[0016] <<<Structure of the laminate>>> FIG. 1 shows a conceptual side view of a laminate 100 according to the present disclosure. As shown in FIG. 1, the laminate 100 according to the present disclosure includes a first base material 11 formed of polyester, a second base material 12 formed of polyester, and a resin layer 20 that adheres the first base material 11 and the second base material 12. Hereinafter, each layer will be described.

[0017] In the present disclosure, the resin layer (resin layer after adhesion) that constitutes the adhesion layer between the first base material and the second base material, and the resin layer (resin layer before adhesion) that is formed on the first base material (or on the second base material) and is a precursor of the adhesion layer before the first base material and the second base material are adhered, may sometimes be simply referred to as the "resin layer" without distinction. When the first base material and the second base material are adhered, the resin layer is pressed and some of its shape changes, but a certain shape can be maintained. Therefore, in terms of the structure / physical properties / characteristics of the resin layer, it can correspond to either the resin layer before adhesion or the resin layer after adhesion.

[0018] <<Resin layer>> The resin layer is formed of a polyester-based hot melt adhesive containing polyester. The hot melt adhesive is a so-called solvent-free adhesive.

[0019] More specifically, it is preferable that the resin layer is formed by applying a polyester-based hot melt adhesive in a molten fibrous state. In other words, it is preferable that the resin layer has a network structure composed of a polyester-based hot melt adhesive. In the present disclosure, the fibers (skeletons) constituting the network structure may sometimes be simply referred to as fibers. Note that this network structure can also be described as a structure in which at least a part of the intersection points between the fibers in an aggregate of fibers composed of a polyester-based hot melt adhesive are fused. By using such a resin layer as an adhesive layer, it is possible to improve the adhesiveness to the base material while enhancing the productivity. Furthermore, since the polyester material is adhered via the polyester-based hot melt adhesive, the ease of recycling can be improved.

[0020] It is preferable that the resin layer according to the present disclosure is not obtained by spraying and melting a powdery resin component (powder material) on the surface of the base material. When the powder material is sprayed on the base material, if the base material is a porous body or the like, the powder material may enter the pores, and the texture of the resulting laminate may be impaired. In addition, when using the powder material, problems such as the need for a dedicated facility for the melting process of the powder when bonding each base material, difficulty in applying to complex shapes such as curved surfaces, and poor productivity may occur. On the other hand, when forming the resin layer without using the powder material (for example, when forming the resin layer by applying a polyester-based hot melt adhesive in a molten fibrous state as described above), such problems are less likely to occur.

[0021] Examples of the polyester constituting the polyester-based hot melt adhesive include One or more polyol components selected from ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, dipropylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, etc., and One or more polycarboxylic acid components selected from polycarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, phthalic acid, terephthalic acid, isophthalic acid, and acid anhydrides thereof, etc., and Resins obtained by condensing them, etc. are mentioned. It is preferable that the polyester contains a structure derived from an aromatic carboxylic acid (including an aromatic carboxylic acid as a monomer constituting the polyester). Also, it is preferable that the polyester contains a structure derived from adipic acid (including adipic acid as a monomer constituting the polyester). Also, it is preferable that the polyester contains a structure derived from terephthalic acid (including terephthalic acid as a monomer constituting the polyester), and it is more preferably PET (polyethylene terephthalate) or PBT (polybutylene terephthalate). The polyester may be a polyester elastomer. A polyester elastomer is a thermoplastic elastomer having a polyester backbone. The polyester elastomer may have a conventionally known structure, and there is no limitation on the soft segment and hard segment that can constitute the elastomer.

[0022] The number average molecular weight of the polyester is preferably 2,000 or more, 4,000 or more, or 6,000 or more, and is preferably 25,000 or less, 20,000 or less, 15,000 or less, or 10,000 or less. Further, the weight average molecular weight of the polyester is preferably 5,000 or more, 10,000 or more, or 20,000 or more, and is preferably 100,000 or less, 80,000 or less, 50,000 or less, or 30,000 or less. By setting the number average molecular weight and / or the weight average molecular weight of the polyester within such ranges, the melt viscosity of the hot melt adhesive is likely to be within an appropriate range, and it is easy to obtain a resin layer excellent in adhesiveness and the like. In the present disclosure, the number average molecular weight and the weight average molecular weight are measured by gel permeation chromatography (GPC) for a solution obtained using tetrahydrofuran (THF) as a solvent, and are converted by a calibration curve prepared using standard polystyrene.

[0023] In addition to the polyester as the main component, the hot melt adhesive may contain conventionally known additives such as fillers, plasticizers, pigments, dyes, anti-aging agents, antioxidants, antistatic agents, flame retardants, antibacterial agents, light stabilizers, stabilizers, and dispersants.

[0024] The average diameter of the fibers constituting the network structure of the resin layer (or the average diameter of the fibers in the aggregate of fibers) is preferably 1 μm or more, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 50 μm or more, or 80 μm or more, and is preferably 500 μm or less, 400 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, or 150 μm or less. By setting the average diameter of the fibers within such ranges, it is possible to increase the adhesiveness while increasing the productivity. The average diameter of the fibers is obtained by observing the resin layer with a microscope, measuring the fiber diameters at any 10 locations, and averaging them.

[0025] The melting point of the polyester-based hot melt adhesive is preferably 170 °C or lower, 160 °C or lower, 150 °C or lower, 140 °C or lower, or 130 °C or lower, and is preferably 100 °C or higher, 105 °C or higher, or 110 °C or higher. By setting the melting point of the polyester-based hot melt adhesive within such a range, a laminate excellent in productivity and high in practicality can be obtained. The melting point of the polyester-based hot melt adhesive is measured from the peak temperature in a differential scanning calorimeter.

[0026] The polyester-based hot melt adhesive preferably has a melt viscosity at 180 °C of 40,000 mPa·s or lower, 35,000 mPa·s or lower, 30,000 mPa·s or lower, 28,000 mPa·s or lower, or 26,000 mPa·s or lower. By setting the melt viscosity of the polyester-based hot melt adhesive within such a range, the shape of the formed network structure (or aggregate of fibers) is likely to be appropriate, or the adhesion to the polyester substrate during melt coating is likely to be excellent, and a laminate having sufficient peel strength is likely to be formed. The lower limit value of the melt viscosity at 180 °C is, for example, 1,000 mPa·s, 2,000 mPa·s, 5,000 mPa·s, 10,000 mPa·s, 15,000 mPa·s, or 20,000 mPa·s. The melt viscosity at 180 °C is measured for the hot melt adhesive heated to a temperature of 180 °C using a parallel plate rheometer under the conditions of an oscillation angle of 10% and an angular frequency of 1 rad / s.

[0027] The hardness (Shore D hardness) of the polyester-based hot melt adhesive is preferably 30 or higher, 32 or higher, or 34 or higher, and is preferably 50 or lower, 48 or lower, or 46 or lower. By setting the hardness in such a range, it is easy to obtain a laminate excellent in adhesiveness.

[0028] <Basis weight> The basis weight of the resin layer is 1 to 100 g / m 2 5 to 80 g / m 2 or 10 to 50 g / m 2is preferable. Further, even if the resin layer of the laminate according to the present disclosure is made lightweight (for example, the basis weight is 30 g / m 2 or less, or 25 g / m 2 or less), it can have sufficient peel strength.

[0029] <<First substrate, second substrate>> The first substrate and the second substrate are made of polyester. The polyester is as described above. The materials of the first substrate and the second substrate are preferably polyethylene terephthalate-based or polybutylene terephthalate-based.

[0030] The structures of the first substrate and the second substrate can be appropriately changed according to the use and the like and are not particularly limited. Examples of the structures of the first substrate and the second substrate include a woven fabric form, a non-woven fabric form, a film form, a foam form, and the like. Further, the shapes and sizes of the first substrate and the second substrate can be appropriately changed according to the use and the like and are not particularly limited. The first substrate and the second substrate may have a complicated shape having irregularities or a curved surface.

[0031] The first substrate and the second substrate may have the same or different structures, materials, etc. Further, a part of the first substrate may be covered by the second substrate (or a part of the second substrate may be covered by the first substrate).

[0032] Since the laminate according to the present disclosure is composed of three layers of polyester material, it is easy to perform recycling treatment without separation. In other words, the laminate according to the present disclosure is easily applicable to a laminate recycling method that performs recycling without separating the laminate.

[0033] <<<Method for manufacturing laminate>>> The method for manufacturing a laminate according to the present disclosure includes a step of providing a resin layer on at least a part of the main surface of the first substrate (resin layer forming step) and a step of bonding the resin layer provided on the first substrate and the second substrate (bonding step).

[0034] When obtaining a laminate on a long strip, a resin layer is formed on a first base material flowing on a line, and then, successively, a second base material is further laminated on the resin layer, whereby the laminate is manufactured.

[0035] <<Resin layer forming step>> In the resin layer forming step, a polyester-based hot melt adhesive heated to a molten fiber state is applied to at least a part of the main surface of the first base material.

[0036] The coating method is not particularly limited as long as it can apply the polyester-based hot melt adhesive in a molten state in a fibrous form. Examples of the coating method include spray coating. As the spray coating, curtain spray, omega spray, spiral spray, summit spray, etc. can be applied. By using spray coating as the coating method, a long laminate can be easily formed.

[0037] The polyester-based hot melt adhesive only needs to be in a molten state, and the heating temperature and the like are not particularly limited. For example, it is preferably held at a temperature 5°C or more, 10°C or more, 20°C or more, or 50°C or more higher than the melting temperature of the polyester-based hot melt adhesive.

[0038] The fiber diameter, thickness (density), etc. of the resin layer are appropriately adjusted according to the coating means (for example, the type of spray head and air pressure), coating speed (for example, line speed), etc.

[0039] In the resin layer forming step, the temperature of the surrounding environment (for example, the temperature of the line itself and the atmosphere) may be adjusted to extend the solidification time of the polyester-based hot melt adhesive.

[0040] In the present disclosure, the configuration in which the resin layer is provided only on the main surface of the first base material has been described. However, the resin layer may be provided on the main surface of the first base material and also on the main surface of the second base material, and the first base material and the second base material may be adhered by bringing the resin layer on the first base material into contact with the resin layer on the second base material.

[0041] <<Next process>> In the next process, the first substrate and the second substrate are bonded via the resin layer to form a laminate.

[0042] In the bonding process, the first substrate and the second substrate may be pressure-bonded using a roller or the like.

[0043] After the bonding process, a process of cooling until the polyester-based hot melt adhesive solidifies or a process of processing the laminate may be provided.

[0044] <<<Applications of the laminate>>> The laminate according to the present disclosure can be used in various applications where polyester materials are used. The laminate according to the present disclosure is used, for example, in vehicle interior materials such as automotive interior materials. Examples of the laminate as an automotive interior material include a laminate including a polyester-based skin material and a polyester-based substrate. More specifically, the laminate according to the present disclosure is used for roof linings (ceiling materials), door trims, pillar trims, headliners, floor undercovers, engine room covers, trunk room panels, package trays, seat backs, and bumpers. In addition to vehicle interior materials, the laminate according to the present disclosure can also be applied to architectural applications (for example, heat insulating materials) and housing applications (for example, carpets).

Example

[0045] Hereinafter, the laminate will be specifically described by way of examples, but the present invention is not limited thereto.

[0046] <<<Example 1>>> <<Manufacture of the laminate>> <Hot melt adhesive> As the hot melt adhesive, the product name "P230" manufactured by TEX YEAR was used. Note that P230 is a PET-based hot melt adhesive. P230 is a polyester-based hot melt adhesive with a melt viscosity of 25,000 mPa·s at 180°C, a melting point of 114°C, and a Shore D hardness of 40 ± 5. Moreover, the polyester contained in P230 has a number average molecular weight (Mn) of about 8,000 and a weight average molecular weight (Mw) of about 26,000.

[0047] <Laminating process and bonding process> A laminate was formed as follows. A long PET skin (the first substrate, a fabric containing PET fibers, basis weight: 250 g / m 2 , thickness: 0.4 mm) was installed on the line so that the PET skin moved along the line from the upstream to the downstream. A spray head fixed to the upstream of the line was provided, and the molten hot melt adhesive was spray-coated in a fibrous form from the spray head, and a two-layer laminate with a resin layer installed on the PET skin was continuously formed. Downstream of the line, a long PET non-woven fabric (the second substrate, a non-woven fabric containing PET fibers, basis weight: 100 g / m 2 , thickness: 2 mm) was laminated and crimped to a thickness of 1 mm to obtain a laminate.

[0048] The average fiber diameter of the obtained resin layer was 109 μm. Also, the basis weight of the obtained resin layer was 20 g / m 2 .

[0049] Figure 2 shows a microscopic photograph (50 times magnification by a microscope) of the appearance of the resin layer when the resin layer was formed under the same conditions except that the PET non-woven fabric was used as the first substrate. As shown in Figure 2, the resin layer according to this example has a network structure formed by a polyester-based hot melt adhesive.

[0050] <<<Example 2-7>>> As the hot melt adhesives, the product name "P311" manufactured by TEX YEAR, the product name "6991" manufactured by Abifor, and the product name "PES730V" manufactured by Bostik were used, and the basis weight of the resin layer was 20 g / m 2 or 35 g / m2 Except for the above, laminates according to Examples 2 to 7 were produced in the same manner as in Example 1. Table 1 shows the melt viscosity, melting point, number average molecular weight, and weight average molecular weight of each hot melt adhesive at 180°C. P311 is a thermoplastic polyester elastomer derived from terephthalic acid, dimethyl ester, 1,4-butanediol, α-hydroxy-ω-hydroxypoly(oxy-1,4-butanediyl), etc. 6991 is a PBT-based hot melt adhesive. PES730V is a PET-based hot melt adhesive.

[0051] <<Evaluation>> <Normal peel strength> For each laminate, the normal peel strength was measured based on the following evaluation method. The measurement results are shown in Table 1. The normal peel strength is considered practical when it is 0.5 N / 25 mm or more, 1.0 N / 25 mm or more, 2.0 N / 25 mm or more, or 4.0 N / 25 mm or more. (Measurement method) After laminate molding, it was cured for 24 hours under the conditions of an environmental temperature of 23 ± 2°C and a relative humidity of 50 ± 4%, and processed into a size of 25 mm × 200 mm to obtain a test sample. Under the conditions of an environmental temperature of 23 ± 2°C and a relative humidity of 50 ± 4%, a peel test was carried out at a peel rate of 200 m / min, and the average value (N = 5) of the peak points at the measurement distance of 80 mm was taken as the peel strength.

[0052] <Wet heat peel strength> For each laminate, the wet heat peel strength (curing time: 400 hours or 600 hours) was measured based on the following evaluation method. The measurement results are shown in Table 1. The wet heat peel strength (curing time: 400 hours or 600 hours) is considered to have excellent performance when it is 0.3 N / 25 mm or more, 0.5 N / 25 mm or more, 1.0 N / 25 mm or more, 2.0 N / 25 mm or more, or 3.0 N / 25 mm or more. Note that for the laminate according to Example 4, the wet heat peel strength was not measured. (Measurement method) After the laminate was formed, it was cured for 400 hours or 600 hours under the conditions of an environmental temperature of 80 °C and a relative humidity of 95%, and then processed into a size of 25 mm × 200 mm to obtain a test sample. Under the conditions of an environmental temperature of 23 ± 2 °C and a relative humidity of 50 ± 4%, a peel test was carried out at a peel rate of 200 m / min, and the average value (N = 5) of the peak points at the measurement distance of 80 mm was taken as the peel strength.

[0053]

Table 1

[0054] As described above, the laminate according to this example has excellent peel strength. Further, it is confirmed that the laminate according to this example can achieve practical peel strength even when composed of a lightweight resin layer with a basis weight of 20 g / m 2 and can have excellent peel strength even when exposed to a wet-heat environment. In addition, since the three layers of the laminate according to this example are formed of a polyester-based material, it is excellent in recyclability. Furthermore, since the laminate according to this example is obtained by melt coating using a hot melt adhesive, it is excellent in manufacturability.

Industrial Applicability

[0055] The laminate according to the present disclosure has sufficient peel strength and is excellent in recyclability. Therefore, it can be preferably applied to vehicle interior materials and the like.

Explanation of Reference Numerals

[0056] 11 First substrate 12 Second substrate 20 Resin layer 100 Laminate

Claims

1. A laminate comprising a first base material formed of polyester, a second base material formed of polyester, and a resin layer that adheres the first base material and the second base material, wherein the resin layer is formed of a polyester-based hot melt adhesive containing polyester, and the laminate has a melt viscosity of the polyester-based hot melt adhesive at 180°C of 40,000 mPa·s or less.

2. The laminate according to claim 1, wherein the resin layer has a mesh structure.

3. The laminate according to claim 1 or 2, wherein the melting point of the polyester-based hot melt adhesive is 170°C or less.

4. The laminate according to claim 1 or 2, wherein the weight average molecular weight of the polyester contained in the polyester-based hot melt adhesive is 50,000 or less.

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