JP4141641B2 - Embossing processing method and manufacturing method of decorative metal plate - Google Patents

Description

【００１９】
【表２】

【００２０】
【産業上の利用可能性】
ＴＭＡ関係値が３０以下である樹脂フィルムを原料とし、冷却ロールが樹脂フィルムと接触する部分の表面温度Ｔｒを、ＴＭＡにより測定される軟化開始温度であるＴｓｓを基準として、Ｔｓｓ±１０（℃）の範囲に設定してエンボス加工処理した場合には、従来の塩ビ樹脂と同等以上のエンボス面を得ることができ、高級感が得られる。
【００２１】
【図面の簡単な説明】
図１は、実施例に係るエンボス処理加工方法の第１態様のロール配置図である。
図２は、実施例に係るエンボス処理加工方法の第２態様のロール配置図である。
図３は、ＴＭＡ関係値の測定曲線の一例である。【Technical field】
[0001]
The present invention relates to a method for embossing a resin film or sheet (hereinafter referred to as “resin film”) excellent in embossing workability, which is used for building materials that require water resistance such as a unit bath, and the production of a decorative metal plate. Regarding the method.
[Background]
[0002]
The decorative metal plate is widely used for building materials that require water resistance such as a unit bath. In this case, the main purpose of coating the resin film on the surface is to give the material metal plate an anticorrosive effect, but at the same time it has the purpose of giving the decorative metal plate a high-class feeling, and the embossed pattern has been conventionally used. It has been widely performed.
Conventionally, the material of the film to which the embossed pattern is added is used mainly for such purposes, mainly from the viewpoint of easy embossing and low cost. It has been.
However, soft vinyl chloride resin is softened by adding and mixing phthalic acids such as DBP (dibutyl phthalate) and DOP (dioctyl phthalate) as a plasticizer in order to facilitate molding. It is difficult to use in places where the height is high, and there are various problems in disposal of products containing them. Furthermore, the aesthetics of the product when the embossed resin film is bonded and laminated to the metal plate is often used depending on the metal plate used, the combination of the metal plate and the resin, or the like. In other words, embossing treatment is used because there is a problem that aesthetics, especially high-grade aesthetic sensibility, are easily affected by the type of resin used in the product for that application and the embossing treatment conditions. It is preferable to carry out under optimum conditions in relation to the resin used.
A hard vinyl chloride resin film from which a plasticizer is excluded has problems in that the processability is inferior and the embossing treatment is generally difficult, and the aesthetic appearance of the resin obtained by the embossing treatment is difficult to obtain. In addition, when using olefin resin polyethylene, polypropylene resin, etc. instead of vinyl chloride resin, the embossability of these resins is good, but when processed after being laminated on a metal plate, the processed part is There is a problem of whitening and impairing aesthetics.
In order to solve this problem, there is a proposal of adding and blending a rubber component. However, when the rubber component is added, a new problem arises in that the polyethylene resin is modified into a soft resin similar to vinyl chloride resin. Polybutylene terephthalate resin is very promising as a coating material in this field because it has excellent properties such as water resistance and little deterioration in strength after standing in water. It was not put into practical use for this purpose because of its badness.
The present invention aims to solve the above-mentioned problems, and has a resin film excellent in embossing workability equal to or higher than that of a conventional soft vinyl chloride resin and a rich and high-quality sensibility coated with the resin film. An object is to provide a decorative metal plate.
DISCLOSURE OF THE INVENTION
[0003]
The present invention has the following features.
That is,
(A)
“A resin film having a TMA (Thermo Mechanical Analysis) relationship value given by the following formula is selected from the resin films of any of the following (1) to (3) :
When embossing processing is performed by a reduction process using an engraving roll, the surface temperature Tr of the portion where the cooling roll comes into contact with the resin film is defined as Tss ± 10 (° C.) based on Tss, which is the softening start temperature measured by TMA. The embossing processing method is characterized in that the embossing processing is performed by setting the range.
(1) a polybutylene terephthalate (PBT) resin film having an intrinsic viscosity (IV) of 1.0 to 1.4,
(2) a blend resin film of 30 parts by weight of PBT resin and 70 parts by weight of polyethylene terephthalate (PET) resin,
(3) Blend resin film of 70 parts by weight of PBT resin and 30 parts by weight of polycarbonate resin,
TMA-related value (° C.) = Tse−Tss,
here,
The softening start temperature Tss (° C.) is measured by TMA,
The penetration depth of the needle into the film when a load of 100 g is applied to a needle with a tip of R = 0.2 or less (tip angle 60 °) at 2 mmφ and the temperature is raised at 10 ° C./min according to JIS-K-7196. In the curve obtained by measurement,
The extension of the straight line portion that is recognized on the low temperature side from the start of the needle to the high temperature side,
It is the temperature obtained by the intersection with the extension of the tangent of the part where the approach speed is maximum to the low temperature side,
The softening end temperature Tse (° C.) is the extension of the tangential line where the entry speed is maximum to the high temperature side,
This is the temperature obtained by the intersection with the extension of the straight line portion observed on the high temperature side after the end of softening to the low temperature side. "
(B)
“A resin film having a TMA (Thermo Mechanical Analysis) relationship value given by the following formula is selected from the resin films of any of the following (1) to (3) :
When embossing processing is performed by a reduction process using an engraving roll, the surface temperature Tr of the portion where the cooling roll comes into contact with the resin film is defined as Tss ± 10 (° C.) based on Tss, which is the softening start temperature measured by TMA. Set to the range of embossing processing,
A method for producing a decorative metal plate, comprising coating a metal plate with the resin film.
(1) a polybutylene terephthalate (PBT) resin film having an intrinsic viscosity (IV) of 1.0 to 1.4,
(2) a blend resin film of 30 parts by weight of PBT resin and 70 parts by weight of polyethylene terephthalate (PET) resin,
(3) Blend resin film of 70 parts by weight of PBT resin and 30 parts by weight of polycarbonate resin,
here,
The softening start temperature Tss (° C.) is measured by TMA,
The penetration depth of the needle into the film when a load of 100 g is applied to a needle with a tip of R = 0.2 or less (tip angle 60 °) at 2 mmφ and the temperature is raised at 10 ° C./min according to JIS-K-7196. In the curve obtained by measurement,
The extension of the straight line portion that is recognized on the low temperature side from the start of the needle to the high temperature side,
It is the temperature obtained by the intersection with the extension of the tangent of the part where the approach speed is maximum to the low temperature side,
The softening end temperature Tse (° C.) is the extension of the tangential line where the entry speed is maximum to the high temperature side,
This is the temperature obtained by the intersection with the extension of the straight line portion observed on the high temperature side after the end of softening to the low temperature side. "
[0004]
As a result of intensive studies on the relationship between the properties of the resin film and the embossability, the inventors of the present invention, as a result, TMA calculated from the softening start temperature Tss (° C) and the softening end temperature Tse (° C) by Thermo Mechanical Analysis (TMA). The relational value (Tse-Tss) is a resin having a value of 30 or less, preferably a resin film containing polybutylene terephthalate resin is used as the resin film, and the cooling roll to be embossed is in contact with the resin film. When the surface temperature Tr of the portion is set to a range of Tss ± 10 (° C.) with reference to Tss, which is the softening start temperature measured by TMA, the embossability of these resin films is A dramatic improvement and embossed film on the decorative metal plate It has been found that a high-grade feeling can be imparted to a product when compared to conventional products.
As a result, even when a resin film having such characteristics is laminated (laminated) and subjected to processing such as bending, there is no problem that the processed portion is whitened and the design is not impaired, and is equivalent to vinyl chloride resin. It was possible to improve the embossability of the polybutylene terephthalate resin as it was, and to maintain the excellent properties of water resistance and strength deterioration after standing in water.
The contents of the present invention will be described below.
[0005]
(Resin film used)
The thickness of the resin film or the like is not particularly limited, but for example, 0.02 to 0.30 mm, preferably 0.080 to 0.150 mm of polybutylene terephthalate (PBT) resin, various ratios of PBT and other resins. Blend resins such as polyethylene terephthalate (PET) resins, polycarbonate resins, ionomer resins and the like, or blends of three or more of these resins, or copolymers of PBT with other resins or compounds, such as isophthalic acid, A resin film of a copolymer with adipic acid or the like, and a composite resin film obtained by laminating the above various resin films at different thickness ratios can be used. These resin films or the like may contain colored resins or the like. The reason for using two or more kinds of blended resins is that, for example, a resin having excellent impact strength but poor adhesion to metal has good adhesion to metal in order to improve only the adhesion. This is a case in which various resins are blended, and the composite resin is used because a resin having excellent adhesive properties is used for the adhesive surface with the metal.
[0006]
The resin used for these resin films is required to have a TMA-related value given by the following formula in the range of 30 or less.
TMA-related value (° C.) = Tse−Tss where Tss (° C.) is a softening start temperature measured by TMA, and Tse (° C.) is a softening end temperature measured by TMA.
When a resin film having such a TMA relation value is used as a raw material resin film and subjected to a rolling embossing process using an engraving roll, a portion of the part in contact with the raw material resin film on the surface of the cooling roll with which the molten resin comes into contact first. It is necessary to set the temperature to a range of Tss ± 10 (° C.) with respect to Tss, which is a softening start temperature measured by TMA, and perform embossing processing.
[0007]
The reason why the TMA-related value of the resin is limited to 30 or less is that the average surface roughness after embossing of the vinyl chloride resin film that has been used in the past was Ra, which was 4.0 μm. This is because the average surface roughness standard for improving the property is 4.0 μm in Ra. The reason why embossability is improved when using a resin film having such a TMA-related value is that a resin having a relatively small range from the softening start point to the softening end point is processed within a certain temperature range close to the softening start point. This is not because the resin can effectively absorb the compressive energy and frictional energy that accompany the embossing treatment in this temperature range, so that the resin can maintain a high degree of strain even after cooling. It is thought.
[0008]
In addition, when a resin film having such a TMA relation value is used as a raw material resin film and subjected to a rolling embossing process using an engraving roll, the temperature Tr of the portion where the surface of the cooling roll is in contact with the raw material resin film is The reason for setting Tss ± 10 (° C.) based on Tss, which is the softening start temperature measured by TMA, is that the resin film embossed in such a temperature range is bonded to a decorative metal plate and laminated. In some cases, the quality of the product is very good. There are still many unclear points regarding the embossing processing temperature and the sensitivity of the laminated resin film to the decorative metal plate, but by controlling the processing temperature in the vicinity of the softening temperature of the resin, film adhesion, etc. It is thought that imparting distortion without causing a high-class feeling.
In general, the relationship between the TMA relationship value and the average surface roughness Ra after embossing of the resin film tends to be inversely correlated. This average surface roughness Ra has a large relationship with the design value (designability) of the product, and a range of 4 or more is considered to be an appropriate value. In addition, the more preferable range of this average surface roughness Ra is 5-8.
[0009]
(Embossing processing method)
Embossing treatment method for resin film, etc., for example, a method of passing a multilayer film directly between chilled rolls, a method of heating a brown film between chilled rolls, a embossing with a rotating screen roll by vacuum force There are various methods such as a method of performing, a hot needle process in which a multilayer film is passed through a perforator (a perforator), and a method of compressing using a marking roll. In the present invention, a resin film supplied from a T die Is embossed using a cooling roll adjusted to a temperature range of Tss ± 10 (° C.) or by a method of rolling down with a cooling roll and an engraving roll. As the embossed shape, various patterns such as a random mat, a square shape, a diamond shape, a deep drawing shape, and a grain pattern can be used according to the needs of the product.
[0010]
(Embossing quality judgment)
The quality of the embossing property of the resin film or the like in the present invention is determined by the surface roughness Ra (μm) after the embossing of the resin film. In general, good embossability means that an embossed pattern is easily formed on the surface of a resin film when it is pressed and embossed with a sculpture roll at a temperature around the melting point of the resin. It means that the embossed pattern is maintained for a time.
The surface roughness is measured by cooling the resin film to room temperature, and then measuring the surface roughness Ra (μm) according to JIS B0601 using a SURFCOM surface roughness meter manufactured by Tokyo Seimitsu Co., Ltd. Of 4.0 or more was considered good embossing property. In this measurement, five resin test pieces are arbitrarily sampled from the resin film that has been subjected to the embossing treatment, and the surface roughness at four different locations is measured for each test piece. Was calculated as the surface roughness Ra (μm).
Moreover, in order to determine the presence or absence of embossed luxury, the embossed film is attached on a decorative metal plate, and then submerged in water for visual determination. As a metal plate used in this case, a wide metal plate such as a steel plate, an aluminum plate, or a copper plate can be used. As the steel plate, a plain steel cold-rolled steel plate having a thickness of 0.10 to 1.20 mm is preferable. Among these, a plain steel cold-rolled steel sheet having a thickness of 0.10 to 0.50 mm is preferable. Among cold-rolled products, low-carbon or ultra-low-carbon aluminum killed steel plates are preferably used, but non-aging steels added with Nb, Ti, etc., chromium-containing steel plates containing 3-18 wt% chromium, stainless steels having various compositions Steel plates and the like can also be used. The surface of these rolled steel plates may be surface-treated.
As the surface treatment method, there are plating treatment, coating treatment, and the like. As the plating treatment, for example, zinc plating, zinc-aluminum alloy plating, zinc-cobalt-molybdenum plating, tin plating, nickel plating, nickel / phosphorous plating, nickel There are cobalt plating, nickel / tin plating, and the coating process is performed by baking and coating various paints according to the properties.
[0011]
When coating an embossed resin film on a metal plate, an epoxy, polyester or cyanoacrylate adhesive may be used, but the resin melting point Tmp (° C) measured by DSC. You may adhere | attach by the method of crimping | bonding on the metal plate heated above. When the resin film and the metal plate are bonded by the thermocompression bonding method, it is preferable to treat the surface of the metal plate so that a strong adhesive force can be obtained. As the surface treatment method of the metal plate, methods such as electrolytic chromic acid treatment and adhesion primer treatment can be employed.
Measurements of specifications necessary for calculating TMA-related values were performed under the following conditions.
Using TMA and TAS-300 manufactured by Rigaku Denki Co., Ltd. Needle when a load of 100 g is applied to a needle with 2 mmφ and tip R = 0.2 or less (tip angle 60 °) and the temperature is raised at 10 ° C./min. The penetration depth into the film was measured according to JIS-K-7196. FIG. 3 shows an example of a measurement curve of TMA related values. Here, the penetration degree of the needle is a value obtained by dividing the penetration depth by the film thickness.
The softening end temperature Tse is a temperature obtained by a tangent intersection of a curve in which the degree of approach changes rapidly as shown in FIG. 3 and the base line after the softening ends. Similarly, the softening start temperature Tss is a temperature obtained from the tangent intersection of the tangent of the curve used in Tse and the base line in the vicinity thereof.
The Tmp measurement by DSC was performed under the following conditions.
A differential calorimeter DSC-7 manufactured by Perkin Elmer was used, and a precisely weighed sample of about 5 mg was heated at 20 ° C./min in a nitrogen gas atmosphere, and the endothermic peak was defined as the melting point Tmp of DSC.
Examples Hereinafter, the present invention will be described more specifically with reference to examples.
[0012]
【Example】
(Example 1)
As shown in FIG. 1, a PBT (polybutylene terephthalate) resin having a TMA relation value of 7.2 and an intrinsic viscosity (IV) of 1.4 is melted, and the T die (resin supply port) 1 The film was extruded onto the engraving roll 3 so that the film thickness was 0.100 mm. A film-like molten resin 2 was sandwiched between an engraving roll 3 and an auxiliary roll 5 to produce a solidified film 6 embossed to a film thickness of 0.100 mm. The processing method of the first aspect is a case where the engraving roll (a grain roll provided with irregularities with an average surface roughness Ra = 11 μm) 3 also serves as a cooling roll. The surface temperature of the part where the engraving roll 3 is in contact with the film-like resin is passed through the engraving roll (cooling roll) 3 so that the roll surface temperature is 215 ° C. because the Tss of the used resin is 221.4 ° C. Adjusted and set the cooling water temperature. The embossed assimilated film 6 was then further cooled to room temperature, 5 specimens were taken at intervals, the surface roughness Ra, which is an embossing index, was measured, and the average value was calculated. As a result, it was 6.7 μm.
[0013]
(Example 2)
As shown in FIG. 2, a PBT resin having a TMA-related value of 3.3 and an intrinsic viscosity (IV) of 1.0 is melted so that the film thickness from the T die 1 becomes 0.100 mm. And extruded onto the cooling roll 4.
A film-like molten resin 2 was sandwiched between an engraving roll 3 and a cooling roll 4 to produce a solidified film 6 embossed to a film thickness of 0.100 mm.
The system of this second aspect is a case where the roll opposite to 3 of the engraving roll (SG roll having an unevenness with an average surface roughness Ra = 11 μm) is a cooling roll. The surface temperature at which the cooling roll 4 is in contact with the resin was adjusted and set to the temperature of the cooling water passing through the cooling roll 4 so that the roll surface temperature was 215 ° C. because the Tss of the resin used was 220.5 ° C. . The embossed solidified film 6 was then further cooled to room temperature, 5 specimens were taken at intervals, the surface roughness Ra, which is an index of the embossing, was measured, and the average value was calculated. As a result, it was 7.0 μm.
[0014]
(Examples 3 to 10)
For resins having different TMA-related values, the molten resin was extruded from a T-die onto a treatment roll and embossed with a film thickness of 0.100 mm by the embossing method of the embodiment of Example 1 or 2. In this case, the surface temperature Tr at which the cooling roll is in contact with the resin was set within Tss ± 10 (° C.) each time based on the Tss measured by TMA of the resin used in advance.
Example 3 was treated with embodiment 1 using a PBT resin with IV = 1.0, Example 4 was treated with embodiment 5 when treated with embodiment 2 using a PBT resin with IV = 1.4. 6 is a blend resin, Example 5 is a blend of 70 parts by weight of polyethylene terephthalate (PET) resin and 30 parts by weight of PBT resin, and Example 6 is a blend of 70 parts by weight of PBT and 30 parts by weight of polycarbonate (PC) resin. It is.
Example 7 is an example of a two-layer film, and a composite laminated film (thickness ratio is 4: 1) of a PBT resin film and a copolymer resin film of 10 mol% of isophthalic acid / PET resin, and Example 8 is a single PET resin film. In the case of taste, Example 9 is a case of simple PC resin, Example 10 is a case of a copolymer of isophthalic acid and PET resin, and other conditions are shown in Table 1.
[0015]
(Comparative Example 1)
In the case where the TMA-related value exceeds 30, an equal weight blended resin of PBT resin and PET resin is embossed in the same manner as in Example 1, and then cooled to room temperature, and 5 specimens The surface roughness Ra, which is an embossing index, was measured and the average value was calculated. As a result, it was 3.2 μm.
[0016]
(Comparative Examples 2-9)
In Comparative Examples 2 to 8, the TMA-related value is 30 or less, but when the temperature Tr of the cooling roll is out of the range of Tss ± 10 (° C.), among these, Comparative Examples 2 to 4 are shifted to a high level. Comparative Examples 5 to 7 are cases in which they are out of the low range. In Comparative Example 3, the resin stuck to the roll during the embossing treatment, and a sample could not be collected. The copolymer of Comparative Example 4 is a copolymer of 11 mol% isophthalic acid and a PET resin, and Comparative Example 7 is a copolymer of 10 mol% adipic acid and PET. Comparative Examples 8 and 9 are multi-layer films, and Comparative Example 8 is a composite laminated film of PBT resin film and isophthalic acid 10 mol% / PET resin copolymer resin film (thickness ratio is 4: 1). Comparative Example 9 is a composite laminated film (thickness ratio is 4: 1) of a PC resin film and a copolymer resin film of 10 mol% of isophthalic acid / PET resin, with a TMA-related value exceeding 30. Other conditions are shown in Table 2.
[0017]
Next, the resin film thus embossed was examined for the presence or absence of a high-grade feeling in combination with a steel plate as follows.
First, an aluminum killed cold-rolled steel sheet having a carbon content of 0.030%, a 0.50 mm-thick steel sheet was galvanized to a thickness of 0.002 mm, and the galvanized steel sheet was sized to 30 × 20 cm. Disconnect. The steel sheet is heated to Tmp ± 10 ° C. measured by DSC, and an embossed resin film is stuck on the surface.
Three such laminated steel plates are prepared, placed on a table in a room where sunlight does not enter, and irradiated with five white fluorescent lamps of 20 W from 1 m above the sample. Five people with different ages and genders are given the following evaluation points by changing the observation place and angle, and the average value of the evaluation points is obtained and comprehensively evaluated.
The evaluation score is 5 points when there is a high-grade feeling equal to or higher than that of the conventional PVC-laminated steel sheet, 4 points when it is slightly inferior to the PVC-laminated steel sheet, but a slightly high-grade feeling is obtained. Three points are given for the feeling of being cheap compared to the laminated steel plate.
When such an evaluation was made, there was a general relationship with the surface roughness, and a TMA-related value of 30 or less was used, and the cooling roll temperature was processed in a temperature range of Tss ± 10 (° C.) by TMA. All the samples had a sufficient high-class feeling. On the other hand, in the case of the samples of the comparative examples that do not match these requirements, a high-class feeling was not obtained or was insufficient. These results are shown in Tables 1 and 2.
[0018]
[Table 1]

[0019]
[Table 2]

[0020]
[Industrial applicability]
Using a resin film having a TMA-related value of 30 or less as a raw material, the surface temperature Tr of the portion where the cooling roll is in contact with the resin film is Tss ± 10 (° C.) with reference to Tss, which is the softening start temperature measured by TMA When the embossing treatment is performed with this range set, it is possible to obtain an embossed surface equal to or higher than that of a conventional vinyl chloride resin, and a high-quality feeling can be obtained.
[0021]
[Brief description of the drawings]
FIG. 1 is a roll layout diagram of a first aspect of an embossing processing method according to an embodiment.
FIG. 2 is a roll layout diagram of a second aspect of the embossing processing method according to the embodiment.
FIG. 3 is an example of a measurement curve of TMA related values.

Claims (2)

A resin film having a TMA (Thermo Mechanical Analysis) relation value given by the following formula is selected from the following (1) to (3) :
When embossing processing is performed by a reduction process using an engraving roll, the surface temperature Tr of the portion where the cooling roll comes into contact with the resin film is defined as Tss ± 10 (° C.) based on Tss, which is the softening start temperature measured by TMA. The embossing processing method is characterized in that the embossing processing is performed by setting the range.
(1) a polybutylene terephthalate (PBT) resin film having an intrinsic viscosity (IV) of 1.0 to 1.4,
(2) a blend resin film of 30 parts by weight of PBT resin and 70 parts by weight of polyethylene terephthalate (PET) resin,
(3) Blend resin film of 70 parts by weight of PBT resin and 30 parts by weight of polycarbonate resin,
TMA-related value (° C.) = Tse−Tss,
here,
The softening start temperature Tss (° C.) is measured by TMA,
The penetration depth of the needle into the film when a load of 100 g is applied to a needle with a tip of R = 0.2 or less (tip angle 60 °) at 2 mmφ and the temperature is raised at 10 ° C./min according to JIS-K-7196. In the curve obtained by measurement,
The extension of the straight line portion that is recognized on the low temperature side from the start of the needle to the high temperature side,
It is the temperature obtained by the intersection with the extension of the tangent of the part where the approach speed is maximum to the low temperature side,
The softening end temperature Tse (° C.) is the extension of the tangential line where the entry speed is maximum to the high temperature side,
This is the temperature obtained by the intersection with the extension of the straight line portion observed on the high temperature side after the end of softening to the low temperature side. A resin film having a TMA (Thermo Mechanical Analysis) relation value given by the following formula is selected from the following (1) to (3) :
When embossing processing is performed by a reduction process using an engraving roll, the surface temperature Tr of the portion where the cooling roll comes into contact with the resin film is defined as Tss ± 10 (° C.) based on Tss, which is the softening start temperature measured by TMA. Set to the range of embossing processing,
A method for producing a decorative metal plate, comprising coating a metal plate with the resin film.
(1) a polybutylene terephthalate (PBT) resin film having an intrinsic viscosity (IV) of 1.0 to 1.4,
(2) a blend resin film of 30 parts by weight of PBT resin and 70 parts by weight of polyethylene terephthalate (PET) resin,
(3) Blend resin film of 70 parts by weight of PBT resin and 30 parts by weight of polycarbonate resin,
here,
The softening start temperature Tss (° C.) is measured by TMA,
The penetration depth of the needle into the film when a load of 100 g is applied to a needle with a tip of R = 0.2 or less (tip angle 60 °) at 2 mmφ and the temperature is raised at 10 ° C./min according to JIS-K-7196. In the curve obtained by measurement,
The extension of the straight line portion that is recognized on the low temperature side from the start of the needle to the high temperature side,
It is the temperature obtained by the intersection with the extension of the tangent of the part where the approach speed is maximum to the low temperature side,
The softening end temperature Tse (° C.) is the extension of the tangential line where the entry speed is maximum to the high temperature side,
This is the temperature obtained by the intersection with the extension of the straight line portion observed on the high temperature side after the end of softening to the low temperature side.

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