JP6887282B2 - Paper container, manufacturing method of paper container, and joint structure - Google Patents

Description

The present invention Kamiyo device, a method of manufacturing a paper container, and relates to joint structures, in particular, Kamiyo instrument polyester resin is laminated on the surface of the interior, a method of manufacturing a paper container, and to a joining structure ..

As a conventional paper container, Patent Document 1 discloses a paper container having a polyethylene terephthalate (hereinafter, may be referred to as “PET”) laminate layer on the inner surface thereof and a method for producing the same.

That is, the conventional paper container disclosed in Patent Document 1 is a paper container composed of a side wall member (body member) and a bottom surface member (bottom plate member), and the side wall member is a PET layer on one surface of the paper base material. Is extruded and laminated, and the bottom member is extruded and laminated with PET layers on both sides of the paper base material. The side wall member is formed in an arc shape by punching out a base paper in which a PET layer is extruded and laminated on the surface of a paper base material, and a cylindrical shape whose upper and lower sides are opened by superimposing and adhering one string and the other string. The PET layer of one string and the PET layer of the other string are heat-welded so that the surface on the side covered by the PET layer is on the inner wall surface side of the side wall member. The bottom member is formed in a disk shape by punching out the base paper. Then, the lower end of the cylindrical side wall member and the peripheral edge of the disk-shaped bottom surface member are brought into contact with each other, and the PET layer on the surface of the side wall member and the PET layer of the bottom surface member are heat-bonded to form a side wall. The member and the bottom member are integrated to form a paper container having a PET layer on the inner surface thereof.

The paper container configured in this way has the property that PET has excellent heat resistance and it is difficult for odors to be absorbed by foods and the like contained in the paper container. Therefore, for example, gratin, cakes, ovens, and the like. It is used for the purpose of accommodating food that has undergone a heating process in a microwave oven or the like.

Japanese Unexamined Patent Publication No. 2012-62099

However, in the conventional paper container, when the side wall member and the bottom surface member are manufactured from different base papers, the polyester resin layer on the surface of the side wall member and the polyester resin layer on the surface of the bottom surface member are bonded at the bonding portion where they are heat-bonded. The strength was low and the adhesive sometimes peeled off.

If the adhesive at the adhesive portion is peeled off, the bottom member and the body portion are released from the integration, which may cause a problem such as leakage of the contents of the paper container.

Further, it is not easy to judge the adhesiveness of the adhesive portion from the appearance of the manufactured paper container, etc., and by directly carrying out a tensile test (by a measuring device or manual work) in the direction of peeling the adhesive portion. It takes time and effort to measure the adhesive strength and evaluate the adhesiveness. Further, a method for evaluating in advance whether or not the adhesiveness after heat bonding is improved in the paper container base paper before bonding has not been generally known.

Further, improving the adhesiveness between polyester resins by such thermal adhesion has been a problem not only in a paper container but also in a bonding structure between other polyester resins.

The present invention has been made to solve the above problems, Kamiyo instrument and the bottom member and the sidewall member are well bonded, a method of manufacturing a paper container, and, to provide a joint structure The purpose.

In order to achieve the above object, the invention according to claim 1 has a bottom surface member in which a first synthetic resin layer made of a first polyethylene terephthalate is laminated on at least the inner surface thereof, and at least a second inner surface thereof. A paper container in which a second synthetic resin layer made of polyethylene terephthalate is laminated, and a part of the inner surface thereof and the inner surface of the peripheral edge of the bottom surface member are connected by thermal adhesion to provide a side wall member that rises upward. The temperature-decreasing crystallization temperature (referred to as "Tc2'α") in the secondary temperature rise of the first polyethylene terephthalate and the temperature-decreasing crystallization temperature (referred to as "Tc2'β") in the secondary temperature rise of the second polyethylene terephthalate. The difference (| Tc2'β-Tc2'α |) is set so as not to exceed 20 ° C., and the crystallinity of the first polyethylene terephthalate and the second polyethylene terephthalate is 3% or more 12 % Or less .

With such a configuration, the adhesive strength of thermal adhesion is improved.

According to a second aspect of the invention, in the configuration of the invention of claim 1 wherein the first polyethylene terephthalate and the second polyethylene terephthalate, while the crystallinity of 5% or less than 12%, its other The crystallinity is 3% or more and 5% or less.

With such a configuration, the adhesive strength of thermal adhesion is further improved.

The invention according to claim 3 is the constitution of the invention according to claim 1 or 2, wherein the bottom surface member includes a base material layer made of paper, a resin laminated on the inner surface side of the base material layer, and an aluminum filler. It is provided with a microwave heating layer containing the above and a first synthetic resin layer laminated on the inner surface side of the microwave heating layer.

With this configuration, the heat generation efficiency of the contained material is improved when heated in a microwave oven.

The invention according to claim 4 is a second synthesis composed of a bottom surface member in which a first synthetic resin layer made of a first polyethylene terephthalate is laminated on at least the inner surface thereof, and a second polyethylene terephthalate on the inner surface thereof. a resin layer is laminated, a second polyethylene terephthalate (referred to as "Tc2'β") phthalate secondary temperature lowering in crystallization temperature and a first polyethylene terephthalate secondary cooling during the Atsushi Nobori crystallization temperature ( "Tc2' A preparatory step for preparing a side wall member whose difference (| Tc2'β-Tc2'α |) from (referred to as α) does not exceed 20 ° C., and a part of the inner surface of the side wall member. Each of the first polyethylene terephthalate and the second polyethylene terephthalate has a crystallinity of 3% or more and 12% or less, which is provided with a welding step of connecting the inner surface of the peripheral edge of the bottom member by thermal adhesion. is there.

With such a configuration, the adhesive strength of thermal adhesion is improved.

The invention according to claim 5 is a first member in which a first synthetic resin layer made of a first polyethylene terephthalate is laminated on at least the surface thereof, and a second synthetic resin made of at least a second polyethylene terephthalate on the surface thereof. It is a bonding structure in which layers are laminated and includes a second member in which at least a part of the surface thereof and at least a part of the surface of the first member are connected by thermal adhesion, and is a secondary rise of the first polyethylene terephthalate. Difference between the temperature-decreasing crystallization temperature (referred to as "Tc2'α") and the temperature-decreasing crystallization temperature (referred to as "Tc2'β") in the secondary temperature rise of the second polyethylene terephthalate (| Tc2'β-Tc2) ´α |) is set not to exceed 20 ° C., and the crystallinity of the first polyethylene terephthalate and the second polyethylene terephthalate is 3% or more and 12% or less .

With such a configuration, the adhesive strength of thermal adhesion is improved.

As described above, the invention according to claim 1 is a paper container in which the bottom surface member and the side wall member are satisfactorily adhered to each other because the adhesive strength of thermal adhesion is improved.

The invention according to claim 2 is a paper container in which the bottom surface member and the side wall member are better adhered to each other because the adhesive strength of thermal adhesion is further improved in addition to the effect of the invention according to claim 1.

The invention according to claim 3 has the effect of the invention according to claim 1 or 2 , and when heated in a microwave oven, the heat generation efficiency of the contained material is improved, so that the contained material is uniformly heated. It becomes a container.

According to the fourth aspect of the present invention, since the adhesive strength of thermal adhesion is improved, it is possible to stably manufacture a paper container in which the bottom surface member and the side wall member are well bonded.

The invention according to claim 5 has a bonded structure in which the first member and the second member are well bonded because the adhesive strength of thermal adhesion is improved.

It is a schematic perspective view which shows the whole shape of the paper container by 1st Embodiment of this invention. It is the schematic end view of the II-II line shown in FIG. It is a schematic enlarged view of the "X" part shown in FIG. It is a figure which shows the measurement result of the primary temperature rise by the differential scanning calorimetry with respect to the 2nd PET of the side wall member of the paper container shown in FIG. It is a figure which shows the measurement result of the secondary temperature rise by the differential scanning calorimetry with respect to the 2nd PET of the side wall member of the paper container shown in FIG. It is a schematic plan view which shows the shape of the paper container base paper before the welding process of the paper container shown in FIG. 1, (1) shows the base paper of a side wall member, and (2) shows the base paper of a bottom member. It is a thing.

1 is a schematic perspective view showing the overall shape of a paper container according to the first embodiment of the present invention, FIG. 2 is a schematic end view of the II-II line shown in FIG. 1, and FIG. 3 is a schematic end view of the line II-II. It is a schematic enlarged view of the "X" part shown by.

With reference to these figures, the paper container 1 has a disk-shaped bottom surface member 3, a cylindrical side wall member 4 connected to the peripheral edge of the bottom surface member 3 and rising upward, and a curl shape on the upper end edge of the side wall member 4. It is composed of an edge winding portion 5 formed in the above, and is opened upward.

In particular, as shown in FIG. 3, the bottom surface member 3 includes a base material layer 7 made of paper, a microwave heating layer 14 containing a resin and an aluminum filler laminated on the inner surface side of the base material layer 7, and a microwave. It is composed of a first synthetic resin layer 8 laminated on the inner surface side of the wave heating layer 14. That is, a first synthetic resin layer 8 made of a first polyethylene terephthalate is laminated on the inner surface of the bottom member 3 (the surface in the inner direction of the paper container 1) by extrusion lamination.

Incidentally, it is preferable that the basis weight of the substrate layer 7 of the bottom member 3 is ^{150g / m 2 ~500g / m 2} , the thickness of the microwave heating layer 14 is preferably 50 microns and 500 microns. With such a configuration, molding can be facilitated and costs can be suppressed. Since the microwave heating layer 14 itself is basically not exposed on the surface of the bottom surface member 3, it does not affect the thermal adhesion between the first synthetic resin layer and the second synthetic resin layer, which will be described later. Absent.

Further, the microwave heating layer 14 is made of a synthetic resin in which an aluminum filler is uniformly contained in the layer. The aluminum filler is an aluminum powder (granular body) having an average particle size (volume average value based on the laser diffraction / scattering method) of 1 μm to 30 μm, and is 30% by weight based on 100% by weight of the entire microwave heating layer 14. Included in ~ 95% by weight. For example, it can be produced by a known method such as an atomizing method. The resin used for the microwave heating layer 14 is not particularly limited, and examples thereof include acrylic resin, polyester resin, polyurethane resin, and nitrocellulose resin.

The thickness of the first synthetic resin layer 8 is preferably 6 μm to 50 μm. If it is 6 μm or less, crystallization and pinholes occur during thermal bonding between the first synthetic resin layer and the second synthetic resin layer, which will be described later, and the heat resistance becomes insufficient, resulting in poor adhesiveness. If it is 50 μm or more, it is difficult for the temperature of the synthetic resin layer to rise uniformly and appropriately during thermal bonding, and the effect of setting the temperature-decreasing crystallization temperature or the degree of crystallization of the present invention, which will be described later, is effective. There is a risk that it will not be played sufficiently. That is, by setting it within the above numerical range, the adhesiveness of thermal adhesion becomes better.

Further, the side wall member 4 is composed of a side wall base material layer 9 made of paper and a second synthetic resin layer 10 made of a second polyethylene terephthalate laminated on one surface side of the side wall base material layer 9. .. That is, a second synthetic resin layer 10 made of a second polyethylene terephthalate is laminated on the inner surface of the side wall member 4 (the surface in the inner direction of the paper container 1) by extrusion lamination.

The thickness of the sidewall base layer 9 of the side wall member 4, it is preferable in view of convenience of the production in the same manner as the substrate layer 7 of the bottom member 3 is basis weight ^{150g / m 2 ~500g / m 2} .

The thickness of the second synthetic resin layer 10 is preferably 6 μm to 50 μm. As in the case of the first synthetic resin layer, if it is 6 μm or less, tunneling or pinholes occur or heat resistance occurs during thermal adhesion between the first synthetic resin layer and the second synthetic resin layer, which will be described later. If the temperature is 50 μm or more, it is difficult for the temperature of the synthetic resin layer to rise uniformly and appropriately during thermal bonding, and the temperature of the present invention, which will be described later, is lowered. There is a risk that the effect of setting the crystallization temperature and crystallization degree will not be sufficiently achieved. That is, by setting it within the above numerical range, the adhesiveness of thermal adhesion becomes better.

In this way, a synthetic resin layer made of PET is laminated on the inner surface of the paper container 1 by extrusion lamination.

Further, the peripheral edge 11 of the bottom surface member 3 is bent downward, and the lower end portion 12 of the side wall member 4 is bent upward so as to cover the bent portion of the peripheral edge 11 of the bottom surface member 3.

Then, at the portion (adhesion portion) included in the “Y” portion of FIG. 3, the inner surface of the bottom surface member 3 and the inner surface of the side wall member 4 are connected by thermal adhesion, and the paper container 1 is opened upward. It is configured to have a shape.

The paper container 1 configured in this way is suitably used for the purpose of storing foods such as gratin inside, for example, by utilizing the heat resistance of PET and the low odor collection of the contained material.

Further, as will be described later, the temperature-decreasing crystallization temperature (referred to as Tc2'α) in the secondary temperature rise of the differential scanning calorimetry (described later) of the first PET laminated on the inner surface of the bottom surface member 3 and the side wall member. The difference (| Tc2'β-Tc2'α |) from the temperature-decreasing crystallization temperature (referred to as Tc2'β) in the secondary temperature rise of the second PET laminated on the inner surface of No. 4 should not exceed 20 ° C. Is set to.

With this configuration, the adhesive strength of thermal adhesion is improved, so that the paper container has the bottom surface member and the side wall member well bonded to each other.

In addition, in this embodiment, as described above, the bottom member 3 is formed with the microwave heating layer 14 containing the resin and the aluminum filler, so that when heated in a microwave oven, the heat generation efficiency of the contained material is high. This is a paper container in which the contents are uniformly heated.

Next, the temperature-decreasing crystallization temperature of PET will be described.

FIG. 4 is a diagram showing the measurement result of the primary temperature rise by differential scanning calorimetry with respect to the second PET of the side wall member of the paper container shown in FIG. 1, and FIG. 5 is a diagram showing the measurement result of the primary temperature rise of the side wall member of the paper container shown in FIG. It is a figure which shows the measurement result of the secondary temperature rise by the differential scanning calorimetry with respect to the 2nd PET.

Differential scanning calorimetry (hereinafter referred to as "DSC") is a thermal analysis method for measuring a melting point, a glass transition point, or the like by measuring the difference in calorimetry between a measurement sample and a reference material. The measurement sample is melted by first raising the temperature from the state of room temperature, and the measurement sample is rapidly cooled from the melted state to eliminate the influence on the crystallinity due to the thermal history. Can be measured.

The DSC shown in FIGS. 4 and 5 is obtained by sampling a predetermined amount (for example, about 4 mg) of a second PET from the inner surface of the side wall member 3 of the paper container 1 described above and measuring it with a differential scanning calorimeter. Here, as the measurement condition, the primary temperature rise means, for example, a sample starting from a state of 40 ° C. and raising the temperature to 285 ° C. at a temperature rise rate of 20 ° C./min. Further, for the secondary temperature rise, for example, after the primary temperature rise, the temperature is maintained at 285 ° C. for 3 minutes, then rapidly cooled in liquid nitrogen, the sample starts from the state of 40 ° C., and the temperature rise rate is 20 ° C./min. The temperature is raised to 285 ° C., maintained at 285 ° C. for 3 minutes, and then lowered to 40 ° C. at a temperature lowering rate of 10 ° C./min.

In these figures, the horizontal axis of the figure represents the temperature [° C.], and the vertical axis represents the measured endothermic / calorific value [mW / mg].

First, referring to FIG. 4, the point 21 represents the glass transition point (hereinafter referred to as “Tg”) in the primary temperature rise, and is 79 ° C. in the second PET of the present embodiment. The glass transition point is the temperature at which the molecular main chain starts or stops rotating or oscillating, although the relative position of the amorphous polymer molecule does not change.

Points 22a and 22b represent the temperature-increasing crystallization temperature (hereinafter referred to as “Tc1”), which is the temperature corresponding to the exothermic peak associated with crystallization in the primary temperature rise, and in the second PET of the present embodiment, , 137 ° C and 156 ° C, respectively.

Further, assuming that the calorific value [J / g] represented by the area of the exothermic peak associated with crystallization in the primary temperature rise is ΔHc1, it is 23 J / g in the second PET of the present embodiment.

Point 23 represents the melting point (hereinafter referred to as “Tm”), which is the temperature corresponding to the endothermic peak associated with melting in the primary temperature rise, and is 250 ° C. in the second PET of the present embodiment.

Further, assuming that the endothermic amount [J / g] represented by the area of the endothermic peak associated with melting in the primary temperature rise is ΔHm, it is 27 J / g in the second PET of the present embodiment.

The crystallinity, which represents the ratio of the crystal part to the total volume of the PET sample, was calculated by the following formula with the heat of fusion of the PET perfect crystal as 117.6 J / g (literature value). In the second PET of the form, it is 3%.

Crystallinity (%) = (ΔHm−ΔHc1) /117.6 × 100
Next, referring to FIG. 5, the point 24 represents the glass transition point (hereinafter referred to as “Tg ′”) in the secondary temperature rise, and is 78 ° C. in the second PET of the present embodiment.

Points 25a and 25b represent the temperature rise crystallization temperature (hereinafter referred to as "Tc1'"), which is the temperature corresponding to the exothermic peak associated with the crystallization in the temperature rise process in which the temperature is raised in the secondary temperature rise. In the second PET of the present embodiment, the temperature is 138 ° C and 153 ° C, respectively.

Further, the calorific value [J / g] represented by the area of the exothermic peak accompanying the crystallization of the heating process in the secondary temperature rise is set to ΔHc1', and in the second PET of the present embodiment, it is 29 J / g. is there.

Point 26 represents the melting point (hereinafter referred to as “Tm ′”) at the secondary temperature rise, and is 249 ° C. in the second PET of the present embodiment.

Further, assuming that the endothermic amount [J / g] represented by the area of the endothermic peak due to melting in the secondary temperature rise is ΔHm ′, it is 30 J / g in the second PET of the present embodiment.

Point 27 represents the temperature lowering crystallization temperature (hereinafter referred to as “Tc2 ′”), which is the temperature corresponding to the exothermic peak associated with the crystallization in the temperature lowering process in which the temperature is lowered from the molten state in the secondary temperature rise. In the second PET of the present embodiment, the temperature is 211 ° C. Even if the same PET is used as the material, Tc2'can change depending on manufacturing conditions such as temperature and thickness at the time of extrusion lamination and temperature / humidity atmosphere conditions. In other words, as described above, a person skilled in the art appropriately changes the manufacturing conditions of at least one of the first PET and the second PET, so that the difference in Tc2'of the two is set within a desired numerical range. Can be done.

Further, assuming that the calorific value [J / g] represented by the area of the exothermic peak accompanying the crystallization of the temperature lowering process in the secondary temperature rise is ΔHc2', it is 36 J / g in the second PET of the present embodiment. is there.

These physical property values can be similarly measured by DSC for the first PET, and affect the propriety of the adhesiveness between the first PET and the second PET by heat sealing. Details will be described later.

Next, FIG. 6 is a schematic plan view showing the shape of the paper container base paper before the welding process of the paper container shown in FIG. 1, (1) shows the side wall member, and (2) shows the bottom surface member. It shows.

First, referring to (1) in the figure, the side wall member 4'is a plan-view arc-shaped sheet in which a second synthetic resin layer made of a second PET is laminated on the surface thereof. For example, it is formed by punching out a base paper in which a second synthetic resin layer is extruded and laminated on one surface of a base material layer made of paper. In this specification, a paper container in a state for forming a side wall member of such a paper container may be referred to as a side wall member base paper.

Further, referring to (2) in the figure, the bottom surface member 3'is a plan-viewing circular sheet in which a first synthetic resin layer made of a first PET is laminated on the surface thereof. For example, a microwave heating layer containing a resin and an aluminum filler is printed or coated on one surface of a base material layer made of paper, and a first synthesis is performed on one surface of the microwave heating layer containing the resin and an aluminum filler. It is composed of punching and molding the base paper in which the resin layer is extruded and laminated. In this specification, a paper container in a state for forming a bottom member of such a paper container may be referred to as a bottom member base paper.

The bottom surface member 3'and the side wall member 4'are set so that the difference in Tc2' between the first PET and the second PET does not exceed 20 ° C.

In the production of the paper container shown in FIG. 1, the peripheral edge of the bottom surface member 3'is bent downward so that the second synthetic resin layer faces outward (in the direction of the side wall member 4), and the side wall member 4 The lower end of ′ is bent upward so as to cover the bent portion of the peripheral edge of the bottom surface member 3 ′. Then, the first PET and the second PET are brought into contact with each other, and are connected by thermal adhesion to achieve an integrated state as shown in FIG. That is, a preparatory step for preparing the bottom surface member 3'and the side wall member 4'described above, and a welding step for connecting the inner surface of a part of the side wall member 4'and the inner surface of the peripheral edge of the bottom surface member 3'by thermal adhesion. Then, the paper container according to the present embodiment is constructed.

At this time, as described above, the difference in Tc2' between the first PET of the bottom surface member 3'and the second PET of the side wall member 4'is set so as not to exceed 20 ° C. Since the adhesive strength is improved, it is possible to stably manufacture a paper container in which the bottom surface member and the side wall member are well bonded.

Here, in the thermal adhesion, a member made of two synthetic resins (the first PET and the second PET in the present embodiment) are brought into contact with each other, and a heating operation is performed at a predetermined heating temperature, pressure, and time setting. Therefore, it is bonded by utilizing the thermoplasticity of the synthetic resin. That is, the two synthetic resins are mixed in a heated and melted state, and crystallize and integrate with cooling.

Therefore, in the first PET and the second PET of the present embodiment, the Tc2'is close (the difference between Tc2' is within the reference value), so that the timing at which crystallization starts from the molten state is close. It is presumed that the adhesive strength of thermal adhesion was improved by satisfactorily integrating the two PETs without separating into two layers, a layer previously crystallized and a layer in a molten state.

From this point of view, the difference in Tc2'(| Tc2'β-Tc2'α |) between the first PET and the second PET is preferably larger than 0 ° C. and 20 ° C. or lower, and preferably 5 ° C. or higher. It is more preferably 20 ° C. or lower. By setting it within this reference value range, the adhesive strength of thermal adhesion is stably improved.

Such a difference in Tc2'can be calculated by measuring the first PET and the second PET by the DSC described above.

Then, the first PET and the Tc2'of the second PET are also measured with respect to the bottom surface member and the side wall member in a state of being configured as the paper container according to the present embodiment through the welding process in the manufacturing process. It is possible to obtain.

That is, in the adhesiveness evaluation method for evaluating the adhesiveness between the bottom surface member and the side wall member of the paper container described above, Tc2'α of the first PET and Tc2'β of the second PET are measured by DSC or the like. It is composed of a first step of acquiring the adhesive and a second step of evaluating the propriety of adhesiveness depending on whether or not the temperature difference (| Tc2'β-Tc2'α |) is within the reference value range.

By doing so, when the difference is within the reference value range, it can be evaluated that the adhesiveness between the bottom member and the side wall member of the paper container is good. On the other hand, the adhesiveness can be evaluated without directly performing a tensile test or the like.

Further, the Tc2'of the first PET and the second PET can also be measured and obtained with respect to the bottom surface member and the side wall member before undergoing the welding process in the manufacturing process.

That is, the adhesiveness evaluation method for evaluating in advance the adhesiveness between the bottom surface member and the side wall member of the paper container base paper for forming the above-mentioned paper container is the first method of the bottom member base paper for forming the bottom surface member of the paper container. Tc2'α of PET and Tc2'β of the second PET of the side wall member base paper for forming the side wall member of the paper container are obtained by measuring with DSC, etc., and the temperature of the first step. It comprises a second step of evaluating the propriety of adhesiveness depending on whether or not the difference (| Tc2'β-Tc2'α |) is within the reference value range.

By doing so, when the difference is within the reference value range, it can be evaluated that the adhesiveness between the bottom member and the side wall member of the paper container is good. Therefore, in the paper container base paper before bonding, the manufacturing process. It is possible to evaluate in advance whether or not the adhesiveness is good when heat-bonding is performed in the above.

Thereby, for example, after manufacturing the side wall member (side wall member base paper) in which the second synthetic resin layer made of the second PET is laminated, the Tc2'of the second PET is measured by DSC to obtain Tc2'β. Then, a bottom member (bottom member base paper) on which a first synthetic resin layer made of a first PET is laminated so that the difference (| Tc2'β-Tc2'α |) becomes Tc2'α within the reference value range is provided. Can be manufactured. That is, it can be suitably used as a guideline for manufacturing conditions.

In the first PET manufactured (extruded and laminated) on the same production line, it can be estimated that Tc2'α is the same when the production conditions are the same. The same applies to Tc2'β in the second PET. Therefore, "acquisition" in the first step of the adhesiveness evaluation method before or after bonding described above means selecting a predetermined number of samples from the manufactured first PET or second PET and setting Tc2'as DSC. For the first PET or the second PET produced under the same production conditions as the sample, Tc2'is inferred from the record.

Next, the crystallinity of the first PET and the second PET will be described.

As described above, in the present specification, the crystallinity refers to the ratio of the crystalline portion to the total volume of PET, and generally, the lower the crystallinity of PET (the closer to 0%) the amorphous portion. It is said that the adhesiveness of thermal adhesion to the adherend is good because the ratio of

However, in the present invention, in the case of thermal adhesion between PETs, if the crystallization degree of one PET is 3% or more and 12% or less and the crystallization is slightly progressing, the crystal of the other PET is crystallized. If the degree of crystallization is 0% or 1% and crystallization has not progressed at all, the adhesiveness becomes poor unlike the general knowledge, and the degree of crystallization is 3% or more 12 like one PET. We have found a new finding that the adhesiveness is good when the crystallization progresses slightly to% or less.

This is because when the crystallization degree of PET is 3% or more and 12% or less and the crystallization is slightly progressing, the molecules are partially regularly arranged, whereas the crystallization is completely progressing. Those that do not have a random molecular arrangement do not dissolve well, and those that do not have a slight crystallization are also considered to have been well compatible and adhered.

That is, it is preferable that the crystallinity of the first polyethylene terephthalate and the second polyethylene terephthalate is 3% or more and 12% or less. With such a configuration, the adhesive strength of thermal adhesion is further improved, so that the paper container in which the bottom surface member and the side wall member are better bonded to each other is obtained. Further, it is more preferable that one of the first polyethylene terephthalate and the second polyethylene terephthalate has a crystallinity of 5% or more and 12% or less, and the other one has a crystallinity of 3% or more and 5% or less. .. With such a configuration, the adhesive strength of thermal adhesion is further improved, so that the paper container in which the bottom surface member and the side wall member are better bonded to each other is obtained.

The degree of crystallization of such PET is appropriately adjusted by intentional or unintentional addition of crystal nuclei, laminating conditions (including crystallization rate and time), decrease in molecular weight due to hydrolysis or thermal decomposition, and the like. By controlling, it can be set within a predetermined numerical range.

Unless otherwise specified, the heat bonding conditions in the present specification are such that the heating temperature is 350 ° C., the pressure is 0.6 MPa, and the heating time is 0.5 seconds, but other heat bonding conditions are not excluded. For example, the heating temperature can be appropriately selected within the range of 200 ° C. to 500 ° C., the pressure 0.2 MPa to 0.6 MPa, and the heating time 0.3 seconds to 1.0 seconds.

The type of base paper used for the paper container of the present invention is not particularly limited, but pure white roll paper, kraft paper, parchment paper, ivory paper, Manila paper, card paper, etc. Cup paper or the like can be used.

Further, the front and back surfaces of the above-mentioned base paper may be printed. This makes it possible to improve the design.

Further, the paper container of the present invention may be top-sealed with a sealant film after containing food or the like inside the container.

Further, the edge winding portion of the paper container of the present invention may be coated with an adhesive, for example, on the outer peripheral surface of the tip portion of the edge winding portion. As a result, the edge winding portion is fixed by the adhesive, so that the springback of the edge winding portion can be suppressed.

Further, in the above embodiment, the edge winding portion is formed on the upper end edge of the side wall member, but the edge winding portion may be omitted.

Further, in the above-described embodiment, the paper container has a specific shape, but other shapes may be used. That is, it may be a paper container in which two types of members are partially connected to each other by heat adhesion, and examples thereof include a paper container in which the bottom surface member is polygonal in a plan view.

Further, in the above embodiment, the paper container is manufactured by a specific manufacturing method, but it may be manufactured by another manufacturing method.

Further, in the above embodiment, the inner surface of the lower end of the side surface member is connected to the inner surface of the peripheral edge of the bottom surface member, but it may be a part of the inner surface of the side surface member.

Further, in the above-described embodiment, the microwave heating layer containing the resin and the aluminum filler is laminated on the bottom surface member, but the layer may not be provided.

Further, in the above embodiment, the first synthetic resin layer made of the first PET is laminated on the inner surface of the bottom surface member, but both sides of the bottom surface member (inner surface and outer surface on the opposite side). ) May be laminated. The same applies to the second synthetic resin layer made of the second PET of the side wall member.

Further, the adhesiveness between the first PET and the second PET according to the present invention is obtained between the side wall member and the bottom surface, for example, when only the bottom surface member is a laminated microwave heating layer containing a resin and an aluminum filler. It can be particularly preferably applied when the base paper is different from the member. This is because the conditions for extrusion laminating the first PET and the second PET are often different.

Further, in the above embodiment, the bottom surface member includes the base material layer and the first synthetic resin layer laminated on the inner surface thereof, but the bottom surface member is substantially heat-bonded. The portion (inner surface) to be provided may be a first synthetic resin layer made of the first PET, and other layers may be sandwiched between the base material layer or appear on a part of the inner surface. Is also good. The same applies to the second synthetic resin layer made of the second PET of the side wall member.

Further, in the above embodiment, the first PET and the second PET are laminated using the same PET as the material, but are laminated using different PET as the material. It may be.

Further, in the above embodiment, the first PET is laminated on the inner surface of the bottom surface member, and the second PET is laminated on the inner surface of the side wall member, but the first PET and the second PET are laminated. Even if the PET of the above is replaced, the effect related to the thermal adhesion of the present invention can be similarly obtained.

Further, in the present specification, polyethylene terephthalate (PET) refers to a thermoplastic polyester obtained by polycondensing terephthalic acid or dimethyl terephthalate with ethylene glycol.

Further, in the above embodiment, the paper container in which the first PET and the second PET are connected by thermal adhesion has been described, but the present invention is not limited to the paper container, and the first PET and the second PET are not limited to the paper container. The present invention can be similarly applied as long as it has a bonded structure in which PET is connected by thermal adhesion. That is, a first member in which a first synthetic resin layer made of a first polyethylene terephthalate is laminated on at least the surface thereof, and a second synthetic resin layer made of a second polyethylene terephthalate are laminated on at least the surface thereof. It is a bonded structure including a second member in which at least a part of the surface and at least a part of the surface of the first member are connected by thermal adhesion, and the temperature lowering crystallization temperature in the secondary temperature rise of the first polyethylene terephthalate. The difference (| Tc2'β-Tc2'α |) between (referred to as "Tc2'α") and the temperature-decreasing crystallization temperature (referred to as "Tc2'β") in the secondary temperature rise of the second polyethylene terephthalate is 20. Anything that is set so as not to exceed ℃ may be used. With such a configuration, the adhesive strength of thermal adhesion is improved, so that the first member and the second member are well bonded to each other to form a bonded structure.

Further, in the above-described embodiment, the above-mentioned setting of the crystallinity of PET is in the paper container, but the adhesiveness evaluation method before or after the above-mentioned bonding step, the paper container The same can be applied to the manufacturing method and the joint structure.

Further, in the above-described embodiment, specific PET is used for each of the first synthetic resin layer and the second synthetic resin layer, but the first synthetic resin layer and the second synthetic resin Polyester resins other than PET can also be used for one or both of the layers. Examples of such a polyester resin include polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN) and the like.

Hereinafter, the present invention will be specifically described based on Examples. The embodiment of the present invention is not limited to the examples.

Samples of Examples and Comparative Examples were prepared in which the second PET of the side wall member according to the embodiment of the present invention described above was used as a heat-bonded adherend and the configuration of the first PET of the bottom member was variously changed. , The various physical properties of each of them and the adhesiveness of thermal adhesion with the second PET were measured.

As the first PET of each sample and the second PET of the side wall member, PET resin BK-6180 manufactured by Mitsubishi Chemical Corporation was used as a material.

The thickness of the synthetic resin layer (the second synthetic resin layer made of the second PET of the side wall member and the first synthetic resin layer made of the first PET of the bottom member of each sample) is commercially available in cross section. Measured with a microscope.

Furthermore, various physical properties were measured by DSC. The measurement method and the calculation method are the same as those described above in the embodiment of the present invention. That is, 4 mg of the second PET and the first PET of each sample are sampled, and the sample starts from the state of 40 ° C. as the primary temperature rise, and the temperature is raised to 285 ° C. at a temperature rise rate of 20 ° C./min. I let you. At this primary temperature rise, Tg, Tc1, ΔHc1, Tm, ΔHm and crystallinity were measured and calculated. Then, after maintaining the temperature at 285 ° C. for 3 minutes, the sample is rapidly cooled in liquid nitrogen, the sample starts from the state of 40 ° C. as a secondary temperature rise, and the temperature rises to 285 ° C. at a temperature rise rate of 20 ° C./min. The temperature was maintained at 285 ° C. for 3 minutes, and then the temperature was lowered to 40 ° C. at a temperature lowering rate of 10 ° C./min. In this secondary temperature rise, Tg', Tc1', ΔHc1', Tm', ΔHm', Tc2', ΔHc2' and | Tc2'β-Tc2'α | were measured and calculated.

Further, as an adhesiveness test, each sample having an adhesive width of 8 mm was obtained by thermally adhering the second PET of the side wall member and each sample at a heating temperature of 380 ° C., a pressure of 0.5 MPa, and a heating time of 0.5 seconds. Was tensile-peeled at a speed of 100 mm / min using a push-pull gauge (Digital Push-Pull Gauge MODEL-9502 manufactured by Aiko Engineering Co., Ltd.), and the adhesive strength [N] was measured. The numerical value of the adhesive strength was a peeling distance of 400 mm and a peak value at that time.

The composition and results of each sample are shown in Table 1 below.

尚、表中、接着性が○（適）とは、熱接着の接着強度が実際の使用に耐える程度に良好であったことを示し、具体的には接着強度が４Ｎ以上であり、側壁部材と各サンプルの底面部材とを試験者の手で剥離したときの剥離箇所において紙剥け（第１のＰＥＴ及び第２のＰＥＴの一方が他方に接着された状態のまま剥離し、基材層の紙が視認できたこと）が発生したことで評価した。

In the table, when the adhesiveness is ○ (appropriate), it means that the adhesive strength of thermal adhesion is good enough to withstand actual use. Specifically, the adhesive strength is 4N or more, and the side wall member. When the bottom member of each sample was peeled off by the tester's hand, the paper was peeled off (one of the first PET and the second PET was peeled off while being adhered to the other, and the base material layer was peeled off. It was evaluated by the fact that the paper was visible).

Further, the adhesiveness of ⊚ (suitable) indicates that the adhesive strength of thermal adhesion was further better than that of ◯ above, and specifically, it was evaluated that the adhesive strength was 5N or more.

Further, when the adhesiveness is × (defective), it means that the adhesive strength of thermal adhesion is poor, specifically, the adhesive strength is less than 4N, and the first PET and the second PET and the second are at the above-mentioned peeling points. It was evaluated by peeling between PETs and no paper peeling.

With reference to the table, in each of Examples 1 to 5, the difference (| Tc2'β-Tc2'α |) between Tc2'α of the first PET and Tc2'β of the second PET is 20. It did not exceed ℃. As a result, it was confirmed that all of these adhesiveness was good.

The crystallinity was 3% in the second PET of the side wall member, 9% in Example 1 where the adhesiveness was ⊚ (suitable), 8% in Example 2, and 6% in Example 3. In Example 4, it was 9%. Further, in Example 5 where the adhesiveness was ◯ (suitable), it was 2%. Further, it was 1% in Comparative Example 1 and 0% in Comparative Example 2 in which the adhesiveness was poor.

1 ... Paper container 3, 3'... Bottom member 4, 4'... Side wall member 7 ... Base material layer 8 ... First synthetic resin layer 10 ... Second synthetic resin layer 11 ... Peripheral 12 ... Lower end 14 ... Microwave Heat-generating layer The same reference numerals in each figure indicate the same or corresponding parts.

Claims (5)

A bottom member in which a first synthetic resin layer made of a first polyethylene terephthalate is laminated on at least the inner surface thereof, and a second synthetic resin layer made of a second polyethylene terephthalate are laminated on at least the inner surface thereof. A paper container including a side wall member in which the inner surface of the portion and the inner surface of the peripheral edge of the bottom surface member are connected by thermal adhesion and rise upward.
The temperature-decreasing crystallization temperature (referred to as "Tc2'α") in the secondary temperature rise of the first polyethylene terephthalate and the temperature-decreasing crystallization temperature (referred to as "Tc2'β") in the secondary temperature rise of the second polyethylene terephthalate. ) the difference between (| Tc2'β-Tc2'α |) is set so as not to exceed 20 ° C.,
The first polyethylene terephthalate and the second polyethylene terephthalate are paper containers having a crystallinity of 3% or more and 12% or less. Claim 1 of the first polyethylene terephthalate and the second polyethylene terephthalate , one of which has a crystallinity of 5% or more and 12% or less, and the other has a crystallinity of 3% or more and 5% or less. The paper container described. The bottom surface member is formed on a base material layer made of paper, a microwave heat generating layer containing a resin and an aluminum filler laminated on the inner surface side of the base material layer, and the inner surface side of the microwave heat generating layer. The paper container according to claim 1 or 2 , further comprising the laminated first synthetic resin layer. A bottom member in which a first synthetic resin layer made of a first polyethylene terephthalate is laminated on at least the inner surface thereof, and a second synthetic resin layer made of a second polyethylene terephthalate are laminated on at least the inner surface thereof. a crystallization temperature in the secondary heating of the second polyethylene terephthalate ( "Tc2'β" to) the first polyethylene terephthalate secondary temperature-lowering crystallization temperature at temperature (the "Tc2'α") A preparatory step for preparing a side wall member whose difference (| Tc2'β-Tc2'α |) is set so as not to exceed 20 ° C.
A welding step of connecting the inner surface of a part of the side wall member and the inner surface of the peripheral edge of the bottom surface member by heat adhesion is provided .
A method for producing a paper container, wherein the first polyethylene terephthalate and the second polyethylene terephthalate both have a crystallinity of 3% or more and 12% or less. At least one of the first member in which a first synthetic resin layer made of a first polyethylene terephthalate is laminated on the surface thereof and a second synthetic resin layer made of a second polyethylene terephthalate on the surface thereof. It is a joint structure including a second member in which the surface of the portion and the surface of at least a part of the first member are connected by thermal adhesion.
The temperature-decreasing crystallization temperature (referred to as "Tc2'α") in the secondary temperature rise of the first polyethylene terephthalate and the temperature-decreasing crystallization temperature (referred to as "Tc2'β") in the secondary temperature rise of the second polyethylene terephthalate. ) the difference between (| Tc2'β-Tc2'α |) is set so as not to exceed 20 ° C.,
The first polyethylene terephthalate and the second polyethylene terephthalate have a bonded structure in which the crystallinity is 3% or more and 12% or less.

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