Thermoforming sheet and packaging container using the same

Abstract

To provide a thermoforming sheet that can be easily removed from a die when the die is used to mold a package container or the like, and a package container produced from the thermoforming sheet.SOLUTION: A thermoforming sheet has: a front face layer constituting a front face; and back face layer constituting a back face. The front face layer and the back face layer each include polyester and a blocking inhibitor. In the front face layer and the back face layer, the polyester and the blocking inhibitor are exposed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a thermoforming sheet and a packaging container using the same. [Background technology]

[0002] 2. Description of the Related Art Known synthetic resin packaging containers are those produced by molding one or more layers of thermoforming sheets containing polyester or the like (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-049704 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when removing the molded packaging container from the mold, the packaging container may be difficult to remove from the mold. In such a case, when removing the molded packaging container from the mold, the packaging container may rub against the mold, causing scratches or the like on the packaging container.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a thermoforming sheet that is easy to remove from a mold when molding a packaging container, etc., using the mold, and a packaging container made from the thermoforming sheet. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention includes the following aspects.

[0007] [1] A thermoforming sheet having a surface layer constituting a surface and a back layer constituting a back surface, the surface layer and the back layer containing polyester and an anti-blocking agent, and the surface and the back surface having the polyester and the anti-blocking agent exposed thereon.

[0008] [2] The thermoforming sheet according to [1], wherein the antiblocking agent is a glass filler.

[0009] [3] The thermoforming sheet according to [2], wherein the glass filler is granular and has an average particle size of 1 μm or more and 10 μm or less.

[0010] [4] The thermoforming sheet according to [1], wherein the antiblocking agent is a polydimethylsiloxane resin.

[0011] [5] The thermoforming sheet according to any one of [1] to [4], wherein the front surface layer and the back surface layer are laminates each including a first layer and a second layer, the first layer containing a polyester having structural units derived from cyclohexanedimethanol and being amorphous, and is located on the outer side of the thermoforming sheet, the second layer containing a polyester having a lower glass transition temperature than the polyester in the first layer, and is located on the inner side of the thermoforming sheet, and the first layer is thinner than the second layer.

[0012] [6] The thermoforming sheet according to any one of [1] to [5], which has an intermediate layer between the front layer and the back layer, and the intermediate layer contains polychlorotrifluoroethylene.

[0013] [7] A packaging container made from the thermoforming sheet described in any one of [1] to [6]. Effect of the Invention

[0014] According to the present invention, it is an object to provide a thermoforming sheet for producing a packaging container that can be easily removed from a mold, and a packaging container produced from the thermoforming sheet that can be easily removed from a mold. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view showing the structure of a thermoforming sheet 1 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing the structure of a thermoforming sheet 6 according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a cross-sectional view of a packaging container made from a thermoforming sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a thermoforming sheet according to an embodiment of the present invention will be described with reference to Figures 1 to 3. In all the following figures, the dimensions and ratios of the components are appropriately changed to make the drawings easier to see.

[0017] <Thermoforming sheet> In this specification, the term "thermoforming sheet" refers to a sheet for producing synthetic resin products, such as packaging containers. In the following description, the "thermoforming sheet" may also be referred to as "sheet."

[0018] Fig. 1 is a cross-sectional view showing the structure of a thermoforming sheet according to an embodiment of the present invention. As shown in Fig. 1, the sheet 1 includes a surface layer 2, an intermediate layer 3, and a back layer 4. The sheet 1 is a laminate in which the surface layer 2, the intermediate layer 3, and the back layer 4 are laminated in this order. Each layer will be described below.

[0019] In this specification, when the name of a resin is mentioned, it refers to the resin itself. For example, when "polyester" is mentioned, it refers to the polyester itself. On the other hand, when a composition is mentioned, it refers to the entire composition including the resin. For example, when "resin composition" or "polyester composition" is mentioned, it refers to the entire composition including the resin or the entire composition including the polyester.

[0020] In this specification, when describing the overall thickness of sheet 1 or the thickness of a layer constituting sheet 1, unless otherwise specified, the thickness refers to the thickness of the sheet before molding.

[0021] (Surface layer and back layer) The surfaces of the front layer 2 and the back layer 4 are the front surface 1a and the back surface 1b of the sheet 1. After being formed into a packaging container, the front surface 1a becomes the outermost layer facing the outside world, and the back surface 1b becomes the outermost layer facing the contents.

[0022] The surface layer 2 and the back layer 4 mainly contain a resin. The resin contained in the surface layer 2 and the back layer 4 is preferably a thermoplastic resin. Examples of the thermoplastic resin include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyamides such as nylon (6-nylon, 6,6-nylon, etc.), polyolefins such as polypropylene (PP) and polyethylene (PE), polyacrylonitrile (PAN), polycarbonate (PC), polyimide (PI), etc. The resin contained in the surface layer 2 and the back layer 4 is preferably a polyester.

[0023] The front surface layer 2 and the back surface layer 4 mainly contain polyester, for example. In this specification, the front surface layer 2 and the back surface layer 4 "mainly contain polyester" means that the content of polyester is at least 50 mass% or more with respect to the total amount constituting the front surface layer 2 and the back surface layer 4.

[0024] The surface layer 2 and the back layer 4 preferably contain 80% by mass or more of polyester based on the total amount of the surface layer 2 and the back layer 4. The surface layer 2 and the back layer 4 more preferably contain 90% by mass or more of polyester based on the total amount of the surface layer 2 and the back layer 4. The upper limit of the content is not particularly limited, but it is preferable that the surface layer 2 and the back layer 4 contain 99% by mass or less of polyester based on the total amount of the surface layer 2 and the back layer 4.

[0025] In the front layer 2 and the back layer 4, optional components other than polyester include known additives such as stabilizers, antistatic agents, and colorants.

[0026] In this specification, "polyester" includes copolyesters. The polyester contained in the front layer 2 and the back layer 4 is a polyester having a structural unit derived from cyclohexanedimethanol, and is an amorphous polyester. Other polyesters include, for example, an amorphous polyester having a structural unit derived from 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or an amorphous polyethylene terephthalate resin modified with a diol component such as spiroglycol or isosorbide.

[0027] In the following description, the polyester having structural units derived from cyclohexanedimethanol and being amorphous is sometimes referred to as "polyester A."

[0028] The polyester A may be a self-produced product or a commercially available product, such as Tritan FX-200 (Eastman Chemical Company).

[0029] The glass transition temperature (Tg) of the polyester contained in the front layer 2 and the back layer 4 is preferably 60° C. or higher, and more preferably 70° C. or higher. There is no particular upper limit to the Tg of the polyester, but it is generally 130° C. or lower.

[0030] The glass transition temperature (Tg) of polyester A is preferably 105° C. or higher, and more preferably 115° C. or higher. There is no particular upper limit to the Tg of polyester A, but it is generally 130° C. or lower.

[0031] The front surface layer 2 and the back surface layer 4 may have the same composition, or the front surface layer 2 and the back surface layer 4 may have different compositions.

[0032] The front layer 2 and the back layer 4 contain an antiblocking agent. In this specification, the "antiblocking agent" is an additive that reduces the friction coefficient of the sheet to make it easier to remove a packaging container formed from the sheet from a mold. The antiblocking agent is not compatible with the polyester matrix, so it is naturally exposed to the front surface 1a and the back surface 1b.

[0033] When removing a packaging container formed from a sheet from a mold, the packaging container may be difficult to remove from the mold. Therefore, when removing the molded packaging container from the mold, the packaging container may rub against the mold, causing scratches or the like on the packaging container. By adding an antiblocking agent, the molded packaging container can be easily removed from the mold, and scratches or the like on the packaging container can be suppressed.

[0034] In this specification, the ease of removal of a molded packaging container from a mold is evaluated by the value of the coefficient of friction of the molded packaging container. When the value of the coefficient of friction of the molded packaging container is small, the molded packaging container is evaluated as being "easy to remove from a mold". The static friction coefficient and dynamic friction coefficient values ​​evaluated as being "easy to remove from a mold" are, for example, 0.40 or less. More preferably, they are 0.39 or less. Even more preferably, they are 0.38 or less. The values ​​of the static friction coefficient and dynamic friction coefficient are measured in accordance with JIS K7125 "Plastics - Films and Sheets - Friction Coefficient Test Method".

[0035] In this specification, the term "good formability" refers to the ability to mold a packaging container while preventing scratches and other damage. The "good formability" is evaluated using a vacuum molding machine (Forming 480, Seiko Sangyo Co., Ltd.). For example, the formability is evaluated when the heating temperature is constant at 200°C and the heating time is 20 seconds.

[0036] (Anti-blocking agent 1) An example of the anti-blocking agent is glass. The glass is a filler, and is preferably granular. The average particle size of the glass filler is preferably 0.1 μm or more. More preferably, it is 1 μm or more. The average particle size of the glass filler is preferably 50 μm or less. More preferably, it is 20 μm or less. Even more preferably, it is 10 μm or less.

[0037] The glass filler may be added to the raw material of the sheet by itself, or may be mixed with polyester and then added to the raw material of the sheet. In this case, the polyester to be mixed with the glass filler is, for example, polyethylene terephthalate or polybutylene terephthalate. The polyester to be mixed with the glass filler may be the same as or different from the polyester that is the raw material of the sheet. In the following description, the "mixture of the glass filler and the polyester to be mixed with the glass filler" may be referred to as an anti-blocking mixture.

[0038] The antiblocking mixture preferably contains 0.1% by weight or more of the glass filler, based on the total amount of the antiblocking mixture. More preferably, it is 0.5% by weight or more. The antiblocking mixture preferably contains 25% by weight or less of the glass filler, based on the total amount of the antiblocking mixture. More preferably, it is 20% by weight or less. Even more preferably, it is 15% by weight or less.

[0039] The anti-blocking mixture may be a self-produced product or a commercially available product, such as Smooth Master G (average particle size of glass filler: 5 μm, glass filler content: 10% by mass, Dainichiseika Color & Chemicals Mfg. Co., Ltd.).

[0040] The amount or concentration of the glass filler added to the front layer 2 and the back layer 4 can be appropriately adjusted. The final concentration of the glass filler added to the front layer 2 and the back layer 4 is preferably 0.05% by mass or more, based on the total amount of the front layer 2 and the back layer 4. More preferably, it is 0.1% by mass or more. The final concentration of the glass filler added to the front layer 2 and the back layer 4 is preferably 10% by mass or less, based on the total amount of the front layer 2 and the back layer 4. More preferably, it is 5% by mass or less. Even more preferably, it is 1% by mass or less.

[0041] (Anti-blocking agent 2) Examples of the blocking inhibitor include polydimethylsiloxane resin. The polydimethylsiloxane resin may be added to the raw material of the sheet by itself, or may be mixed with silicone and then added to the raw material of the sheet. In this case, the silicone to be mixed with the polydimethylsiloxane resin may be polydimethylsiloxane resin or other silicone. Examples of the silicone to be mixed with the polydimethylsiloxane resin include polymethylphenylsiloxane, polymethylhydrogensiloxane, aralkyl-modified polydimethylsiloxane, polyether-modified polydimethylsiloxane, alkyl-modified polydimethylsiloxane, higher fatty acid-modified polydimethylsiloxane, fluoroalkyl-modified polydimethylsiloxane, amino-modified polydimethylsiloxane, epoxy-modified polydimethylsiloxane, carbinol-modified polydimethylsiloxane, carboxyl-modified polydimethylsiloxane, phenol-modified polydimethylsiloxane, and silanol-modified polydimethylsiloxane. In the following description, the "mixture of polydimethylsiloxane resin and silicone for mixing the polydimethylsiloxane resin" may be referred to as anti-blocking silicone.

[0042] The anti-blocking silicone preferably contains 20% by mass or more of polydimethylsiloxane resin, more preferably 40% by mass or more, based on the total amount of the anti-blocking silicone. The anti-blocking silicone preferably contains 80% by mass or less of polydimethylsiloxane resin, more preferably 60% by mass or less, based on the total amount of the anti-blocking silicone.

[0043] The anti-blocking silicone may be self-produced or commercially available, for example MB50-010 (DuPont Toray Specialty Materials).

[0044] The amount or concentration of the polydimethylsiloxane resin added to the surface layer 2 and the back layer 4 can be appropriately adjusted. The final concentration of the polydimethylsiloxane resin added to the surface layer 2 and the back layer 4 is preferably 0.1% by mass or more, based on the total amount of the surface layer 2 and the back layer 4. More preferably, it is 1% by mass or more. The final concentration of the polydimethylsiloxane resin added to the surface layer 2 and the back layer 4 is preferably 10% by mass or less, based on the total amount of the surface layer 2 and the back layer 4. More preferably, it is 5% by mass or less.

[0045] The front surface layer 2 may include a first layer 21 and a second layer 22. The back surface layer 4 may include a first layer 41 and a second layer 42. The compositions of the first layer 21 and the first layer 41 may be the same or different. The compositions of the second layer 22 and the second layer 42 may be the same or different.

[0046] The front layer 2 and the back layer 4 "include a first layer located on the outside and a second layer located on the inside," "the first layer is thinner than the second layer," and further, "the Tg of the composition of the first layer is higher than the Tg of the composition of the second layer," so that the sheet can have both heat resistance and ease of molding. The difference between the Tg of the composition of the first layer and the Tg of the composition of the second layer is preferably 15°C or more and 65°C or less. More preferably, it is 25°C or more and 55°C or less.

[0047] When the surface layer 2 and the back layer 4 are made of a single layer using a resin composition with a low Tg for ease of molding, the heat resistance is deteriorated. On the other hand, when the surface layer 2 and the back layer 4 are made of a single layer using a resin composition with a high Tg for heat resistance, molding becomes difficult.

[0048] The Tg of the resin composition of the first layer located outside the front layer 2 and the back layer 4 is made higher than the Tg of the resin composition of the second layer located inside them. Furthermore, the thickness of the first layer is made thinner than that of the second layer. This makes it possible to achieve both heat resistance and ease of molding.

[0049] Heat resistance is evaluated assuming a molding machine. Two heating plates are placed one above the other, with a gap of 100 mm between them, and each sheet is inserted midway between the two heating plates without touching them. For example, the temperature of the heating plates is set to 120°C. After the sheet is inserted in the designated position, it is heated by the heat of the heating plates and becomes soft. The time it takes for the softened sheet to drip onto the lower heating plate is measured to evaluate heat resistance.

[0050] The first layer 21 mainly contains polyester A. The first layer 21 is located on the outer side of the thermoforming sheet 1 .

[0051] The second layer 22 mainly contains a polyester having a lower Tg than that of polyester A. The second layer 22 is located on the inner side of the thermoforming sheet.

[0052] The thickness ratio between the first layer 21 and the second layer 22 can be appropriately adjusted. The first layer 21 is preferably thinner than the second layer 22.

[0053] The first layer 41 mainly contains polyester A. The first layer 41 is located on the outer side of the thermoforming sheet 1 .

[0054] The second layer 42 mainly contains a polyester having a lower Tg than that of polyester A. The second layer 42 is located on the inner side of the thermoforming sheet.

[0055] The thickness ratio between the first layer 41 and the second layer 42 can be appropriately adjusted. The first layer 41 is preferably thinner than the second layer 42.

[0056] In the following description, a "polyester having a Tg lower than that of polyester A" may be referred to as polyester B. Examples of polyester B include modified polyesters containing structural units derived from diethylene glycol, 1,4-butanediol, 1,3-propanediol, or isophthalic acid.

[0057] The Tg of the polyester B contained in the second layers 22 and 42 is preferably 60° C. or higher, and more preferably 70° C. or higher. The upper limit of the Tg of the polyester B contained in the second layers 22 and 42 is not particularly limited as long as it is lower than the Tg of the polyester A contained in the first layers 21 and 41, but is generally 120° C. or lower.

[0058] The Tg of the polyester A composition constituting the first layers 21 and 41 is preferably 100° C. or higher. More preferably, it may be 105° C. or higher, or may be 115° C. or higher. The upper limit of the Tg of the polyester A composition constituting the first layers 21 and 41 is not particularly limited, but is generally 130° C. or lower.

[0059] The Tg of the polyester B composition constituting the second layers 22 and 42 is preferably 60° C. or higher, and more preferably 70° C. or higher. The upper limit of the Tg of the polyester B composition contained in the second layers 22 and 42 is not particularly limited as long as it is lower than the Tg of the polyester A composition contained in the first layers 21 and 41, but is generally 120° C. or lower.

[0060] The thicknesses of the front surface layer 2 and the back surface layer 4 can be appropriately adjusted. The thicknesses of the front surface layer 2 and the back surface layer 4 are preferably 60% or more of the total thickness of the sheet 1, and more preferably 70% or more. The thicknesses of the front surface layer 2 and the back surface layer 4 are preferably 90% or less of the total thickness of the sheet 1, and more preferably 80% or less.

[0061] The thickness of the surface layer 2 can be appropriately adjusted, for example, to 80 μm or more, and for example, to 120 μm or less.

[0062] The thickness of the back surface layer 4 can be appropriately adjusted, and is, for example, 80 μm or more. The thickness of the back surface layer 4 is, for example, 120 μm or less.

[0063] (Middle class) The intermediate layer 3 has a water vapor barrier function. The intermediate layer 3 is a layer provided between the front layer 2 and the back layer 4.

[0064] The intermediate layer 3 mainly contains a fluororesin. Since the intermediate layer 3 contains a fluororesin, the sheet 1 can suppress the penetration of moisture.

[0065] In the intermediate layer 3, optional components other than the fluororesin include known additives such as stabilizers, antistatic agents, and colorants.

[0066] The fluororesin contained in the intermediate layer 3 is preferably polychlorotrifluoroethylene (PCTFE), which is excellent among fluororesins in terms of water vapor barrier properties, mechanical strength, gas barrier properties, ease of molding, and the like.

[0067] The thickness of the intermediate layer 3 can be appropriately adjusted, for example, to be 15 μm or more and 50 μm or less.

[0068] (Adhesive resin layer) The adhesive resin layers 5a and 5b are layers disposed between the surface layer 2 and the intermediate layer 3, and between the intermediate layer 3 and the back layer 4, respectively. The adhesive resin layers 5a and 5b bond the surface layer 2 and the intermediate layer 3, and the intermediate layer 3 and the back layer 4, respectively.

[0069] The adhesive resin contained in the adhesive resin layers 5a and 5b may be a known one. The adhesive resin layers 5a and 5b preferably contain mainly an acid-modified polyolefin.

[0070] In the adhesive resin layers 5a and 5b, examples of optional components other than the acid-modified polyolefin include known additives such as stabilizers, antistatic agents, and colorants.

[0071] The acid-modified polyolefin contained in the adhesive resin layers 5a and 5b may be, for example, acid-modified polyethylene, acid-modified polypropylene, etc. The acid-modified polyolefin contained in the adhesive resin layers 5a and 5b is preferably acid-modified polyethylene. The acid group of the acid-modified polyolefin is preferably maleic anhydride. That is, the acid-modified polyethylene is preferably maleic anhydride-modified polyethylene.

[0072] The compositions of the adhesive resin layers 5a and 5b may be the same or different.

[0073] The thickness of the adhesive resin layers 5a and 5b is not particularly limited, but is, for example, 10 μm or more, and is, for example, 30 μm or less.

[0074] The thickness of the sheet 1 in this embodiment can be appropriately adjusted, and is, for example, 250 μm or more. The thickness of the sheet 1 is, for example, 400 μm or less, and may be 300 μm or less.

[0075] The sheet 1 may include a surface layer 2, an intermediate layer 3, a back layer 4, an adhesive resin layer 5a, and an adhesive resin layer 5b, but other layers may be appropriately introduced between the surface layer 2 and the back layer 4 as necessary. In this case, an adhesive resin layer may be introduced between the introduced layer and the other layer.

[0076] 2 is a cross-sectional view showing the structure of a thermoforming sheet 6 according to an embodiment of the present invention. The sheet 6 is a sheet in which the front layer 2 and the back layer 4 of FIG. 1 have the same composition and do not contain any other layer between the front layer 2 and the back layer 4.

[0077] The sheet 6 mainly contains a resin. The resin contained in the sheet 6 is preferably a thermoplastic resin. Examples of the thermoplastic resin include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyamides such as nylon (6-nylon, 6,6-nylon, etc.), polyolefins such as polypropylene (PP) and polyethylene (PE), polyacrylonitrile (PAN), polycarbonate (PC), polyimide (PI), etc. The resin contained in the sheet 6 is preferably a polyester.

[0078] The sheet 6 mainly contains polyester, for example. In this specification, the sheet 6 "mainly contains polyester" means that the content of polyester relative to the total amount constituting the sheet 6 is at least 50 mass % or more.

[0079] The sheet 6 preferably contains 50% by mass or more of polyester based on the total amount constituting the sheet 6. The sheet 6 more preferably contains 80% by mass or more of polyester based on the total amount constituting the sheet 6. There is no particular upper limit to the content, but the polyester content is preferably 99% by mass or less based on the total amount constituting the sheet 6.

[0080] In the sheet 6, optional components other than polyester include known additives such as stabilizers, antistatic agents, and colorants.

[0081] In this specification, "polyester" includes copolyesters. The polyester contained in the sheet 6 is a polyester having a structural unit derived from cyclohexanedimethanol, and is an amorphous polyester. Other polyesters include, for example, an amorphous polyester having a structural unit derived from 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or an amorphous polyethylene terephthalate resin modified with a diol component such as spiroglycol or isosorbide.

[0082] The glass transition temperature (Tg) of the polyester contained in the sheet 6 is preferably 60° C. or higher, and more preferably 70° C. or higher. There is no particular upper limit to the Tg of the polyester, but it is generally 130° C. or lower.

[0083] The glass transition temperature (Tg) of polyester A is preferably 105° C. or higher, and more preferably 115° C. or higher. There is no particular upper limit to the Tg of polyester A, but it is generally 130° C. or lower.

[0084] The sheet 6 contains an antiblocking agent. The antiblocking agent is not compatible with the polyester matrix, and is therefore naturally exposed on the front and back surfaces of the sheet 6.

[0085] 2, the sheet 6 may include a first sublayer 71 and a second sublayer 72 on the outside of the sheet 6. That is, the sheet 6 may include the first sublayer 71, a main layer 73, and the second sublayer 72. That is, the sheet 6 is laminated in the order of the first sublayer 71, the main layer 73, and the second sublayer 72.

[0086] If the sheet 6 is made of a single layer of a resin composition with a low Tg for ease of molding, the heat resistance will be poor, whereas if the sheet 6 is made of a single layer of a resin composition with a high Tg for heat resistance, molding will be difficult.

[0087] The sheet 6 "includes a first sublayer 71 and a second sublayer 72 located on the outside," "the first sublayer 71 and the second sublayer 72 are thinner than the main layer 73," and further, "the Tg of the composition of the first sublayer 71 and the second sublayer 72 is higher than the Tg of the composition of the main layer 73," so that the sheet can have both heat resistance and ease of moldability. The difference between the Tg of the composition of the first sublayer 71 and the second sublayer 72 and the Tg of the composition of the main layer 73 is preferably 15° C. or more and 65° C. or less. More preferably, it is 25° C. or more and 55° C. or less.

[0088] Heat resistance is evaluated assuming a molding machine. Two heating plates are placed one above the other, with a gap of 100 mm between them, and each sheet is inserted midway between the two heating plates without touching them. For example, the temperature of the heating plates is set to 120°C. After the sheet is inserted in the designated position, it is heated by the heat of the heating plates and becomes soft. The time it takes for the softened sheet to drip onto the lower heating plate is measured to evaluate heat resistance.

[0089] The first sublayer 71 and the second sublayer 72 mainly contain polyester A. The first sublayer 71 and the second sublayer 72 are located on the outer sides of the thermoformable sheet 6.

[0090] The main layer 73 mainly contains a polyester having a lower Tg than that of polyester A. The main layer 73 is located on the inner side of the thermoforming sheet 6.

[0091] The thickness ratio of the first sublayer 71 and the second sublayer 72 to the main layer 73 can be appropriately adjusted. The first sublayer 71 and the second sublayer 72 are preferably thinner than the main layer 73.

[0092] In the following description, a "polyester having a Tg lower than that of polyester A" may be referred to as polyester B. Examples of polyester B include modified polyesters containing structural units derived from diethylene glycol, 1,4-butanediol, 1,3-propanediol, or isophthalic acid.

[0093] The Tg of polyester B contained in the main layer 73 is preferably 60° C. or higher, and more preferably 70° C. or higher. The upper limit of the Tg of polyester B contained in the main layer 73 is not particularly limited as long as it is lower than the Tg of polyester A contained in the first sublayer 71 and the second sublayer 72, but is generally 120° C. or lower.

[0094] The Tg of the polyester A composition constituting the first sublayer 71 and the second sublayer 72 is preferably 100° C. or higher. More preferably, it may be 105° C. or higher, or may be 115° C. or higher. There is no particular upper limit to the Tg of the polyester A composition constituting the first sublayer 71 and the second sublayer 72, but it is generally 130° C. or lower.

[0095] The Tg of the polyester B composition constituting the main layer 73 is preferably 60° C. or higher, and more preferably 70° C. or higher. The upper limit of the Tg of the polyester B composition constituting the main layer 73 is not particularly limited as long as it is lower than the Tg of the polyester A composition constituting the first sublayer 71 and the second sublayer 72, but is generally 120° C. or lower.

[0096] The thickness of the sheet 6 in this embodiment can be appropriately adjusted, for example, to 250 μm or more and 400 μm or less. The thickness of the sheet 6 is, for example, 300 μm or less.

[0097] <Packaging container> In this specification, a synthetic resin product is manufactured using a thermoforming sheet as a material. The synthetic resin product is, for example, a packaging container. An example of the packaging container is a press-through pack. The use of the packaging container is not limited, but it is used, for example, to package medicines and the like. A part of the packaging container may be replaced with a lid material such as aluminum foil.

[0098] Fig. 3 is a cross-sectional view of a packaging container made of a thermoforming sheet. As shown in Fig. 3, the packaging container 8 includes a container 9 and a lid material 10. The size of the packaging container can be appropriately adjusted according to the size of the contents. The contents are, for example, medicines.

[0099] The container 9 is manufactured by molding the thermoforming sheet 1. As described above, when the thermoforming sheet 1 is used as the material, the surface layer 2 forms the surface 1a, which forms the surface 9a of the container 9 facing the outside world. The back layer forms the back surface 9b, which forms the surface 9b of the container 9 facing the contents.

[0100] The lid material 10 has water vapor barrier properties. The lid material 10 may be produced by forming the thermoforming sheet 1. The lid material 10 may be a known lid material, for example, aluminum foil.

[0101] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiment. The shapes and combinations of the components shown in the above embodiment are merely examples, and various modifications can be made based on the design, specifications, etc., without departing from the spirit of the present invention. EXAMPLES

[0102] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0103] <Preparation of thermoforming sheets> Using the resins described below, a thermoforming sheet was manufactured in which a surface layer, an adhesive resin layer, an intermediate layer, an adhesive resin layer, and a back layer were laminated in that order. The resins that were the raw materials for each layer were separately heated and melted, and then simultaneously multi-layered film-forming was performed using an extruder capable of simultaneous multi-layer extrusion molding to obtain a thermoforming sheet consisting of five layers. The resins that were the raw materials for each layer were as follows.

[0104] Polyesters were used for the front and back layers. Tritan FX-200 (Tg: 119°C, Eastman Chemical Company) was used as polyester A for the first layer. Clapet KS710B-8S (Tg: 82°C, Kuraray) was used as polyester B for the second layer. Polyester B is a polyester that has a structural unit derived from cyclohexanedimethanol and is not an amorphous polyester.

[0105] For the middle layer, DF0050-C1 (Daikin Industries, Ltd.) was used as PCTFE.

[0106] For the adhesive resin layer, Admer (registered trademark) maleic anhydride-modified polyethylene (Mitsui Chemicals, Inc.) was used as the maleic anhydride-modified polyethylene.

[0107] Example 1 Polyester A was used for the outer first layer of the front and back layers, and polyester B was used for the inner second layer. The thickness of the first layer of the front and back layers was 20 μm, and the thickness of the second layer was 80 μm. Admer was used for the resin adhesive layer. The thickness of the adhesive resin layer was 15 μm. PCTFE was used for the intermediate layer. The thickness of the intermediate layer was 20 μm. The overall thickness of Example 1 was 250 μm.

[0108] A glass filler was added as an anti-blocking agent to the polyester of the front and back layers. The glass filler was added in the form of an anti-blocking mixture. Smooth Master G (average particle size of glass filler: 5 μm, glass filler content: 10 mass%, Dainichiseika Color & Chemicals Mfg. Co., Ltd.) was added as the anti-blocking mixture. The final concentration of the glass filler was 0.48 mass% relative to the total amount constituting the front and back layers. Since the anti-blocking agent is not compatible with the polyester matrix, it is naturally recognized that it is exposed on the surface.

[0109] Example 2 A sheet of Example 2 was produced in the same manner as in Example 1, except that the final concentration of the glass filler was 5 mass % relative to the total amount constituting the front layer and back layer.

[0110] Example 3 A sheet of Example 3 was produced in the same manner as Example 1, except that polydimethylsiloxane resin was added as an anti-blocking agent. The polydimethylsiloxane resin was added in the form of anti-blocking silicone. MB50-010 (DuPont Toray Specialty Materials) was added as the anti-blocking silicone. The final concentration of polydimethylsiloxane resin was 1.5% by mass relative to the total amount constituting the front layer and back layer. Since the anti-blocking agent is not compatible with the polyester matrix, it is naturally recognized that it will be exposed on the surface.

[0111] Example 4 A sheet of Example 4 was produced in the same manner as Example 1, except that polydimethylsiloxane resin was added as an antiblocking agent. The composition was the same as that of Example 3, but the final concentration of polydimethylsiloxane resin was 3 mass% relative to the total amount constituting the front layer and back layer.

[0112] Comparative Example 1 A sheet of Comparative Example 1 was produced in the same manner as in Example 1, except that no antiblocking agent was added.

[0113] The configurations of Examples 1 to 4 and Comparative Example 1 are shown in Table 1. In the following table, PEsA refers to polyester A. PEsB refers to polyester B. The numbers in parentheses indicate the thickness of each layer. For example, PEsA(20) indicates that the layer containing polyester A is 20 μm thick.

[0114] [Table 1]

[0115] Table 2 shows whether an antiblocking agent was added, and the type and amount of the antiblocking agent added. When Smooth Master G (average particle size of glass filler: 5 μm, glass filler content: 10 mass%, Dainichiseika Color & Chemicals Mfg. Co., Ltd.) was added as an antiblocking agent, it was recorded as "glass" and the final concentration of "glass filler" relative to the total amount constituting the front and back layers was recorded. When MB50-010 (DuPont Toray Specialty Materials Co., Ltd.) was added as an antiblocking agent, it was recorded as "silicone" and the final concentration of "polydimethylsiloxane resin" relative to the total amount constituting the front and back layers was recorded. When no antiblocking agent was added, it was recorded as "none."

[0116] [Table 2]

[0117] <Evaluation of thermoforming sheets> (Evaluation of the ease of removing molded packaging containers from the mold) In accordance with JISK7125 "Plastics - Films and Sheets - Friction Coefficient Test Method", the static friction coefficient μ of each molded sheet was measured. S and the coefficient of dynamic friction μ D The coefficient of friction was measured. If the coefficient of friction is small, the molded packaging container is easy to remove from the mold. Conversely, if the coefficient of friction is large, the molded packaging container is difficult to remove from the mold. The results are shown in Table 3.

[0118] Examples 1 to 4, in which an antiblocking agent was added, had smaller friction coefficient values ​​than Comparative Example 1, in which no antiblocking agent was added, indicating that the antiblocking agent reduced the friction coefficient.

[0119] (Evaluation of total light transmittance and haze) The total light transmittance of each molded sheet was measured in accordance with JISK7361-1 "Plastics - Test method for total light transmittance of transparent materials - Part 1: Single beam method." Total light transmittance is the ratio of the total transmitted light flux to the parallel incident light flux of the test piece.

[0120] In addition, the haze of each sheet before molding was measured in accordance with JIS K7136 "Determination of haze of plastics-transparent materials". Haze is the percentage of transmitted light that deviates from the incident light by 0.044 rad or more due to forward scattering among the transmitted light that passes through the test piece. Haze is generally used as an index to express the degree of cloudiness of transparent materials. If the haze value is 50% or more, the test sheet is like cloudy glass, and it is difficult to see objects through the test sheet. Conversely, if the haze value is less than 50%, it is possible to see objects through the test sheet. The results are shown in Table 3.

[0121] Comparative Example 1, in which no antiblocking agent was added, and Examples 1 and 3, in which the amount of antiblocking agent added was relatively small, had a haze value of less than 50%, and objects could be seen through the test sheet. On the other hand, Examples 2 and 4, in which the amount of antiblocking agent added was relatively large, had a haze value of 50% or more, and objects could not be clearly seen through the test sheet.

[0122] (Evaluation of moldability) To evaluate formability, a vacuum forming machine (Forming 480, Seiko Sangyo Co., Ltd.) was used to verify suitability for vacuum forming. Formability was verified at a constant heating temperature of 200°C for a heating time of 20 seconds. When removing the molded product from the mold, it was visually checked to see if scratches or other damage had occurred. The results are shown in Table 3. When scratches or other damage on the molded product could not be confirmed with the naked eye, it was indicated as "A." When scratches or other damage on the molded product could be confirmed with the naked eye, it was indicated as "B."

[0123] The molded products of the sheets of Examples 1 to 4 were not visually confirmed to have scratches or the like, and could be molded without any problems. On the other hand, the molded product of the sheet of Comparative Example 1 was scratched when the molded product was removed from the mold. Considering this together with the results of the evaluation of the ease of removing the molded packaging container from the mold, it is presumed that the molded product of the sheet of Comparative Example 1 was scratched because the molded packaging container was difficult to remove from the mold. However, the mechanism by which the molded products of the sheets of Examples 1 to 4 did not have scratches or the like is not limited to the above-mentioned presumed mechanism.

[0124] [Table 3]

[0125] From the above results, it was found that the present invention is effective. [Explanation of symbols]

[0126] 1: thermoforming sheet, 1a: surface, 1b: back surface, 2: surface layer, 21: first layer, 22: second layer, 3: intermediate layer, 4: back surface layer, 41: first layer, 42: second layer, 5a: adhesive resin layer, 5b: adhesive resin layer, 6: thermoforming sheet, 71: first sub-layer, 72: second sub-layer, 73: main layer, 8: packaging container, 9: container, 9a: surface facing the outside world, 9b: surface facing the contents, 10: lid material

Claims

1. A surface layer constituting the surface; A thermoforming sheet having a back surface layer constituting a back surface, The front layer and the back layer contain polyester and an antiblocking agent, The polyester and the anti-blocking agent are exposed on the front surface and the back surface, The front surface layer and the back surface layer each include a first layer and a second layer, the first layer is a polyester having structural units derived from cyclohexanedimethanol and is amorphous; the first layer is located on the outer side of the thermoforming sheet; the second layer comprises a polyester having a glass transition temperature lower than that of the polyester of the first layer, and is located on an inner side of the thermoforming sheet; The first layer is a thermoforming sheet that is thinner than the second layer.

2. The glass transition temperature of the first layer is higher than the glass transition temperature of the second layer; 2. The thermoforming sheet according to claim 1, wherein the difference between the glass transition temperature of the first layer and the glass transition temperature of the second layer is 15°C or more and 65°C or less.

3. 3. The thermoforming sheet according to claim 1, wherein the antiblocking agent is a glass filler.

4. 4. The thermoforming sheet according to claim 3, wherein the glass filler is in a granular form and has an average particle size of 1 μm or more and 10 μm or less.

5. 3. The thermoforming sheet according to claim 1, wherein the antiblocking agent is a polydimethylsiloxane resin.

6. An intermediate layer is present between the front surface layer and the back surface layer, The thermoforming sheet according to any one of claims 1 to 5, wherein the intermediate layer comprises polychlorotrifluoroethylene.

7. A packaging container made from the thermoforming sheet according to any one of claims 1 to 6.

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