JP3676862B2 - Method for producing moldable release sheet - Google Patents

Description

【００４５】
表１より明らかなように、実施例１〜４に示した本発明の製造方法による離型シートは残存接着率及び剥離強度に優れるものであった。
【００４６】
［実施例５］
未延伸シートの厚みを０．３ｍｍとする以外は実施例１と同様に処理して離型シートを得た。この離型シートを真空成形機にて、加熱軟化させ真空成形をおこなって、縦２０ｍｍ、横１０ｍｍ、深さ５ｍｍのトレイ状成形体（１６個採り：トレイ状成形体の内側が離型層）を得た。この離型シートの成形性は良好であった。
【００４７】
［実施例６］
未延伸シートの厚みを０．４ｍｍとする以外は実施例１と同様に処理して離型シートを得た。この離型シートを真空成形機にて、加熱軟化させ真空成形をおこなって、縦２００ｍｍ、横１００ｍｍ、深さ２０ｍｍのトレイ状成形体（１個採り：トレイ状成形体の内側が離型層）を得た。この離型シートの成形性（型トレース性等）は良好であった。また、得られた成形体を積み重ねた際の成形体同士の離型性（滑り性）は良好なものであり、成形体に蓋材をヒートシールした後蓋材を剥離する際のピール性も良好なものであった。尚、得られた成形体の底部を切り出し、離型層の特性を測定した結果、離型強度が９ｇ／ｉｎ、残存接着率が９８％でいずれも良好であった。
【００４８】
［比較例３］
実施例１で用いたものと同様の未延伸シートの片面に、Ｐｔ触媒硬化型シリコーンの固形分濃度３重量％塗工液（信越化学工業（株）製・ＫＳ−８４７Ｈ）をグラビアコーターにて塗布した後、長手方向に５ｋｇ／ｍの張力を加えて１００℃で２０秒間加熱硬化させようとしたが、急激な幅方向の収縮変形が発生し、実用的な離型シートを作ることができなかった
【００４９】
【発明の効果】
本発明の製造方法では、特定の塗膜成分を用い、特定の条件で処理して離型層を得るため、離型性及び成形性に優れ、包装材等に有用な成形可能な離型シートを製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a moldable release sheet based on a polyester sheet, and more particularly to a method for producing a moldable release sheet that is excellent in mold release and moldability and is useful for packaging materials and the like.
[0002]
[Prior art]
The unstretched polyester sheet is formed by a thermoforming method such as a vacuum forming method or a pressure forming method, and is used for a packaging container or the like. Such a polyester sheet has a drawback that the releasability between sheets when handling sheets, the releasability between containers when stacking molded containers, and the like are insufficient.
[0003]
In order to improve such a defect, a method of applying silicone oil as a release agent to the surface of the polyester sheet has been adopted. However, in such a method, since silicone oil is not a durable film, it is lost from the surface of the polyester sheet during molding or processing, and the mold release property is deteriorated. There is a drawback that the printability of the oil-transferred surface is poor.
[0004]
Further, in order to improve the above-described drawbacks of lowering the mold release property and poor printability, a method of laminating a thermosetting silicone release layer on the polyester sheet can be considered. However, in this method, it is necessary to heat-treat the silicone release layer at a temperature of at least 100 ° C. for 10 seconds or more, and under such conditions, the unstretched polyester sheet is deformed by heat shrinkage or the like. The disadvantage that the polyester crystallizes and the transparency and moldability deteriorate.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a moldable release sheet having a release layer that eliminates the disadvantages of the prior art and has excellent release properties and durability.
[0006]
[Means for Solving the Problems]
The object of the present invention is, according to the present invention, to coat at least one surface of a polyester unstretched sheet with a coating film comprising a room temperature curable isocyanate silane compound and a terminal-modified silicone oil, and to treat the treatment temperature (T: ° C.) and treatment. Achieved by a method for producing a moldable release sheet, characterized in that a release layer is provided by treating the time (θ: time) to satisfy the conditions represented by the following formulas (I) and (II): Is done.
[0007]
[Expression 2]
T × θ ≧ 800 Formula (I)
20 ≦ T ≦ 50 (Formula (II))
[0008]
Hereinafter, the present invention will be described in detail.
[0009]
[polyester]
In the present invention, an unstretched polyester sheet is used as the base sheet. The polyester constituting the polyester sheet is a linear saturated polyester composed of an aromatic dibasic acid component and a diol component, such as polyethylene terephthalate, Trimethylene terephthalate, polytetramethylene terephthalate, polypentamethylene terephthalate, polyhexamethylene terephthalate, polyethylene-2,6-naphthalate, polytetramethylene-2,6-naphthalate, polyhexamethylene-2,6-naphthalate, polytrimethylene Preferred examples include -2,6-naphthalate, polypentamethylene-2,6-naphthalate, polycarbonate of 4,4'dihydroxydiphenyl-2,2-propane, and the like.
[0010]
Moreover, the above-mentioned homopolymer may be sufficient as polyester, and the copolymer which copolymerized other components as an aromatic dibasic acid component and / or a diol component may be sufficient as it. Further, a mixture of two or more of the above homopolymers or copolymers may be used.
[0011]
Other improvers can be blended with the above polyester. For example, a compound having a sulfonate group such as sodium dodecylbenzenesulfonate as an antistatic agent, and organic or inorganic fine particles having an average particle diameter of about 0.01 to 20 μm as a lubricant, for example, 0.005 to 20% by weight It can be contained in a proportion. Specific examples of such fine particles include inorganic particles such as calcium carbonate, kaolin, silicon oxide, and barium sulfate, and organic particles such as crosslinked polystyrene resin particles, crosslinked silicone resin particles, and crosslinked acrylic resin particles. Polyesters that do not contain these modifiers can also be used.
[0012]
[Polyester sheet]
The polyester unstretched sheet (hereinafter abbreviated as “polyester sheet”) in the present invention is preferably a sheet made of substantially amorphous polyester because the moldability of the sheet becomes good. The thickness of the polyester sheet is preferably 50 to 500 μm.
[0013]
The polyester sheet in the present invention can be produced by a conventionally known method. For example, a method in which polyester is dried, melted in an extruder, extruded from a die (for example, T-die, I-die, etc.) onto a cooling body, and rapidly cooled to form a substantially amorphous unstretched sheet is particularly preferable. preferable. As this cooling body, a conventionally used rotary cooling drum is preferable, for example, a cooling drum having a metal, plastic, rubber or the like on its surface, and a liquid or gaseous refrigerant is circulated inside the drum surface. It is preferable to have a structure capable of forcibly cooling.
[0014]
[Release layer]
In the present invention, a coating film comprising a room temperature curing type isocyanate silane compound and a terminal-modified silicone oil is applied to at least one surface of the polyester sheet, and the processing temperature (T: ° C.) and processing time (θ: time) are as follows. A release layer is provided by treatment so as to satisfy the conditions represented by the formula (I) and the following formula (II).
[0015]
[Equation 3]
T × θ ≧ 800 Formula (I)
20 ≦ T ≦ 50 (Formula (II))
This room temperature curing type isocyanate silane compound is a compound having a general structural formula represented by the following formula (A).
[0016]
[Chemical 1]
Si (NOC) X ₃ ...... Formula (A)
In the formula (A), X is a NOC group, an R group (hydrocarbon group) or an OR group (alkoxy group). However, R shows hydrocarbon groups, such as a methyl group, an ethyl group, a phenyl group, and a vinyl group.
[0017]
Examples of such room temperature curable isocyanate silane compounds include compounds represented by the following formulas (B), (C), and (D).
[0018]
[Chemical formula 2]
Si (NOC) ₄ ...... Formula (B)
[0019]
[Chemical 3]
Si (NOC) _4-n R _n ...... Formula (C)
In the formula (C), n is 1, 2 or 3; R represents a hydrocarbon group such as a methyl group, an ethyl group, a phenyl group or a vinyl group.
[0020]
[Formula 4]
Si (NOC) _4-n (OR) _n ...... Formula (D)
In the formula (D), n is 1, 2 or 3; R represents a hydrocarbon group such as a methyl group, an ethyl group, a phenyl group or a vinyl group.
[0021]
The terminal-modified silicone oil in the present invention is a silicone oil having a functional group (a group having an active hydrogen such as a hydroxyl group, a carboxyl group or an amino group) capable of reacting with isocyanate at the end of the molecule.
[0022]
As such a terminal-modified silicone oil, for example, trade names of DKQ8-778 and DKQ8-779 manufactured by Dow Corning Co., Ltd., or trade names of KR-213, KR-214, and KR-216 manufactured by Shin-Etsu Chemical Co., Ltd. are used. The oil etc. can be mentioned.
[0023]
In the present invention, a coating film comprising the above room temperature curing type isocyanate silane compound (hereinafter abbreviated as “silane compound”) and terminal-modified silicone oil (hereinafter abbreviated as “silicone oil”) is applied. The amount ratio is preferably 1 to 20 parts by weight of silicone oil with respect to 100 parts by weight of the silane compound. When the amount ratio is within this range, the release layer and the back surface non-transferability of the obtained release layer can be made excellent.
[0024]
In the present invention, a coating film comprising a silane compound and silicone oil is applied, and the treatment temperature (T: ° C.) and the treatment time (θ: hour) are represented by the following formula (I) and the following formula (II). The release layer is provided by processing so as to satisfy the conditions.
[0025]
[Expression 4]
T × θ ≧ 800 Formula (I)
20 ≦ T ≦ 50 (Formula (II))
[0026]
When the product of the treatment temperature (T: ° C.) and the treatment time (θ: hour) is less than 800, the reaction between the functional group of the silane compound and the silicone oil becomes insufficient, and the release layer becomes easy to transfer. Since processing (for example, printing) in the process causes trouble, it is not preferable.
[0027]
Further, when the treatment temperature (T: ° C.) is less than 20 ° C., the curing reaction of the release layer does not proceed sufficiently. Further, if the treatment temperature (T: ° C.) exceeds 50 ° C., the thermal shrinkage of the base polyester sheet becomes remarkable, and it becomes difficult to maintain the flatness.
[0028]
The treatment temperature (T: ° C.) and treatment time (θ: time) are preferably the conditions shown by the following formula (III) and the following formula (IV).
[0029]
[Equation 5]
T × θ ≧ 900 Formula (III)
30 ≦ T ≦ 45 ...... Formula (IV)
[0030]
The product of the processing temperature (T: ° C.) and the processing time (θ: time) may be in any range as long as it satisfies the above formula (I), but is represented by the following formula (V). It is preferable that the conditions are satisfied because the transparency and moldability of the release sheet can be kept better.
[0031]
[Formula 6]
T × θ ≦ 5000 …… Formula (V)
[0032]
A conventionally known method can be used for applying a coating film composed of a silane compound and silicone oil on at least one surface of the polyester sheet. Examples of such methods include a coating method (bar coating method, doctor blade method, reverse roll coating method, gravure roll coating method, etc.), a method of applying a pad by pressing it, and the like. The coating amount of the coating film is preferably about 5 to 100 g / m ^2. When the coating amount of the coating film is within this range, the release property of the coating film becomes good and the curing can be carried out in a short time, which is advantageous in production.
[0033]
[Release sheet]
The release sheet in the present invention is a sheet that has good stretchability when heated and can be molded. Examples of the molding herein include heat such as vacuum molding, pressure molding, and vacuum / pressure molding. This refers to a molding method for obtaining a molded body using a sheet such as compression molding such as molding or press molding as a starting material. Of these, vacuum forming is particularly preferable.
[0034]
Moreover, as a molded object obtained from the release sheet in this invention, tray shape, cup shape, etc. can be mentioned, for example. Of these, a tray-like one having a drawing ratio (ratio of the length in the vertical or horizontal direction of the molded body and the depth of the molded body) of 1 or less, and more preferably 0.5 or less is particularly preferable.
[0035]
【Example】
Hereinafter, the present invention will be further described with reference to examples. Each characteristic value of the release layer was measured by the following method.
[0036]
1. Peel strength Polyester adhesive tape (Nitto 31B) is bonded to the release layer surface of the polyester sheet, and it is pressed with a 5 kg pressure roller and left for 20 hours, and then the tensile strength (g / in) between the release layer and the adhesive tape is tested. Measured with a machine.
[0037]
In addition, the preferable range of peeling strength is 5-100 g / in. When the peel strength is 5 g / in or less, the resin sheet or the like may be peeled off from the release sheet when the laminated sheet obtained by laminating the resin sheet or the like on the release sheet is taken up. In addition, when the peel strength is 100 g / in or more, it may be difficult to peel the resin sheet or the like from the laminated sheet when it is peeled and separated.
[0038]
2. The peel strength after sticking the residual adhesive polyester pressure-sensitive adhesive tape (Nitto 31B) on the cold-rolled stainless steel plate (SUS304) specified in JIS G4305 is measured and defined as the basic adhesive strength (f ₀ ). The polyester adhesive tape is pressed against the surface of the sample film where the release layer is coated with a 5 kg pressure roller, left for 30 seconds, and then peeled off. And the peeled adhesive tape is affixed on said stainless steel plate, the peeling force of this bonding part is measured, and it is set as residual adhesive force (f). Based on the obtained basic adhesive strength (f ₀ ) and residual adhesive strength (f), the residual adhesive rate is obtained using the following formula.
[0039]
[Expression 7]
Residual adhesion rate (%) = (f / f ₀ ) × 100
[0040]
In addition, the preferable range of a residual adhesive rate is 85% or more. When the residual adhesive rate is less than 85%, for example, when the release sheet is wound and stored in a roll, the component constituting the release layer is transferred to the surface of the adjacent sheet (so-called back transfer), and the release is performed. This is not preferable because the characteristics of the layer may be poor, and the characteristics such as adhesion between adjacent sheet surfaces may be poor. Incidentally, when the curing reaction between the silane compound and the silicone oil in the release layer is insufficient, the residual adhesion rate becomes insufficient.
[0041]
[Examples 1 to 4]
Polyethylene terephthalate having an intrinsic viscosity (measured with an O-chlorophenol solution at 25 ° C.) of 0.60 is melted with an extruder and extruded onto a rotating cooling drum maintained at 25 ° C. to obtain an unstretched sheet having a thickness of 200 μm. It was. On one side of this unstretched sheet, a silane compound having the composition shown in Table 1 and an ethyl acetate solution of silicone oil were applied by a roll coater, and then the solvent was evaporated by air blowing at room temperature to form a coating film. It was wound up into a shape. The release sheet wound up in the form of a roll was heat-treated under the conditions shown in Table 1, and the curing reaction was advanced to form a release layer. Table 1 shows the properties of the release layer thus obtained.
[0042]
[Comparative Example 1]
An unstretched polyethylene terephthalate sheet was obtained in the same manner as in Example 1 except that no coating film was applied. Table 1 shows the surface characteristics of this sheet.
[0043]
[Comparative Example 2]
A release sheet was obtained in the same manner as in Example 1 except that the heat treatment was performed under the conditions shown in Table 1. The properties of this release layer are shown in Table 1.
[0044]
[Table 1]

[0045]
As is clear from Table 1, the release sheets produced by the production methods of the present invention shown in Examples 1 to 4 were excellent in the residual adhesion rate and the peel strength.
[0046]
[Example 5]
A release sheet was obtained in the same manner as in Example 1 except that the thickness of the unstretched sheet was 0.3 mm. This release sheet is heated and softened with a vacuum forming machine to perform vacuum forming, and 20 mm long, 10 mm wide, 5 mm deep tray-shaped molded bodies (16 pieces: the inside of the tray-shaped molded body is the release layer) Got. The moldability of this release sheet was good.
[0047]
[Example 6]
A release sheet was obtained in the same manner as in Example 1 except that the thickness of the unstretched sheet was 0.4 mm. This release sheet is heated and softened with a vacuum forming machine, and vacuum forming is performed. A tray-like molded body having a length of 200 mm, a width of 100 mm, and a depth of 20 mm (one piece: the inside of the tray-like molded body is a release layer) Got. The moldability (mold traceability etc.) of this release sheet was good. Moreover, the mold release property (sliding property) between the molded products when the obtained molded products are stacked is good, and the peelability when peeling the cover material after heat-sealing the cover material on the molded product is also good. It was good. The bottom of the obtained molded product was cut out and the properties of the release layer were measured. As a result, the release strength was 9 g / in and the residual adhesion rate was 98%.
[0048]
[Comparative Example 3]
A non-stretched sheet similar to that used in Example 1 was coated with a Pt catalyst-curable silicone solid content concentration 3 wt% coating solution (manufactured by Shin-Etsu Chemical Co., Ltd., KS-847H) on a gravure coater. After applying, I tried to heat and cure at 100 ° C for 20 seconds by applying a tension of 5 kg / m in the longitudinal direction, but sudden shrinkage deformation in the width direction occurred and a practical release sheet could be made. There was no [0049]
【The invention's effect】
In the production method of the present invention, a specific release film component is used and processed under specific conditions to obtain a release layer. Therefore, the mold release sheet is excellent in releasability and moldability and is useful for packaging materials and the like. Can be manufactured.

Claims (2)

On at least one surface of the polyester unstretched sheet, a coating film composed of a normal temperature curable isocyanate silane compound and a terminal-modified silicone oil is applied, and the processing temperature (T: ° C) and processing time (θ: time) are represented by the following formula (I) And a method for producing a moldable release sheet, characterized in that a release layer is provided by processing so as to satisfy the condition represented by the following formula (II).

The method for producing a moldable release sheet according to claim 1, wherein the coating film contains 1 to 20 parts by weight of a terminal-modified silicone oil with respect to 100 parts by weight of the normal temperature curable isocyanate silane compound.