JP2019171617A - Release sheet - Google Patents

Abstract

To provide a release sheet that has a release layer having a small change in peel force with time, and particularly having a stable peel force during high-temperature storage even though prescribing that the initial peel force is set higher.SOLUTION: The release sheet has a base material and a release layer and is formed such that the release layer is a layer formed from a release agent composition including (A) a polybutadiene having a crosslinkable functional group and (B) a melamine compound, in which the crosslinkable functional group is a functional group reactive with the melamine compound (B) and the polybutadiene (A) having a crosslinkable functional group includes 1,2-vinyl unit in an amount of 50 mol% or more based on the total constitutional unit of the polybutadiene (A).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a release sheet.

Generally, a release sheet has a base material, such as paper, a plastic film, or polyethylene laminated paper, and a release layer provided on the base material. The release layer is formed by applying and curing a release agent composition containing a reactive compound on a substrate.
Release sheets are widely used as, for example, a protective sheet for a pressure-sensitive adhesive layer possessed by a pressure-sensitive adhesive sheet, a process sheet for producing a resin sheet, a process film for forming a ceramic green sheet, a process film for producing synthetic leather, and the like.

As a release agent composition for forming a release layer, a silicone release agent composition containing a silicone compound such as silicone resin, siloxane, or silicone oil is widely used.
However, the silicone compound may migrate to the contact surface with the release layer, for example, the adhesive layer surface of the adhesive sheet. It may also gradually evaporate after the transition.
For this reason, when a release sheet having a release layer formed from a silicone-based release agent composition is used in an electronic material application, the silicone compound may migrate to the electronic component and cause corrosion or malfunction of the electronic component.

Then, examination which forms a peeling layer is performed, without using a silicone type release agent composition.
When a release layer formed from a non-silicone release agent composition is used, the release force with the object laminated on the release layer is usually compared to a release layer formed from a silicone release agent composition, Get higher. However, when the retention property (drop-off resistance) of the object to be laminated is prioritized, a higher peeling force is preferable, and therefore a non-silicone release agent composition is often selected.
As such a non-silicone release agent composition, for example, Patent Document 1 is formed from a release agent composition containing at least a polyolefin, an isocyanate having three or more isocyanate groups in a molecule, and a polyolefin polyol. A release sheet having a release layer is described.

JP 2011-52207 A

  However, a release layer formed of a release agent composition other than the silicone release agent composition has a large change in peel force with time, and the peel force tends to increase greatly with time. In particular, when the peeling force of the release layer is set to be high, a change with time tends to be large, and a release layer having a stable release force is rare.

  Therefore, the present invention is to provide a release sheet having a release layer having a stable release force even at a high temperature storage even when the initial release force is set to be high, even if the initial release force is small. Objective.

  The present inventors have found that a release sheet having a release layer formed from a release agent composition containing a specific polybutadiene and a melamine compound can solve the above problems.

That is, the present invention relates to the following [1] to [5].
[1] A release sheet having a substrate and a release layer, wherein the release layer is a layer formed from a release agent composition containing a polybutadiene (A) having a crosslinkable functional group and a melamine compound (B). The crosslinkable functional group is a functional group that reacts with the melamine compound (B), and the polybutadiene (A) having the crosslinkable functional group is a 1,2-vinyl compound based on the total constituent units of the polybutadiene (A). A release sheet containing 50 mol% or more.
[2] The release sheet according to [1], wherein the crosslinkable functional group is a hydroxyl group.
[3] The release sheet according to [1] or [2], wherein the polybutadiene (A) having a crosslinkable functional group is a hydrogenated product having a bromine number of 10 g / 100 g or less.
[4] The peel strength of the release sheet after being exposed to a high temperature environment of 70 ° C. for 7 days is defined as the peel strength after heating Y, and the peel strength of the release sheet in the state without exposure to the high temperature environment is initially set. [1] to [1], wherein the change rate represented by {(peeling force after heating Y−initial peel force X) / initial peel force X} × 100 is within ± 30% when the peel force is X. 3] The release sheet according to any one of the above.
[5] The release sheet according to any one of the above [1] to [4], wherein the peeling force when peeling from the pressure-sensitive adhesive layer is 2500 mN / 20 mm or more.

  According to the present invention, it is possible to provide a release sheet having a release layer having a stable release force even at a high temperature storage even when the initial release force is set to be high, even when the initial release force is set to be high. It becomes possible.

It is a schematic sectional drawing of the peeling sheet of 1 aspect of this invention.

In the present specification, the number average molecular weight (Mn) is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.
Moreover, in this specification, an "active ingredient" refers to the component remove | excluding the dilution solvent among the components contained in a peeling agent composition.

[Composition of release sheet]
The release sheet of the present invention has a base material and a release layer provided on the base material.
FIG. 1 is a schematic cross-sectional view illustrating a release sheet of one embodiment of the present invention. The release sheet 1 includes a base material 10 and a release layer 11 provided on the base material 10. The release layer 11 is a cross-linked product formed from a release agent composition containing a specific polybutadiene (A) and a melamine compound (B).
Note that other layers such as an easy adhesion layer and an antistatic layer (not shown) may be provided between the substrate 10 and the release layer 11.
Hereinafter, the release layer and the substrate constituting the release sheet of the present invention will be described.

<Peeling layer>
The release layer of the release sheet of the present invention can be formed from a release agent composition containing a specific polybutadiene (A) and a melamine compound (B).
Hereinafter, the release agent composition which is a material for forming the release layer will be described.
In the following description, “content of each component relative to the total amount of active ingredients in the release agent composition” is regarded as “content of each component in the release layer formed from the release agent composition”. You can also.

(Release agent composition)
The release agent composition is a specific polybutadiene (A), that is, a polybutadiene (A) having a crosslinkable functional group and containing 50 mol% or more of a 1,2-vinyl body on the basis of all constituent units of the polybutadiene (A). And a melamine compound (B).
In the following description, “polybutadiene (A) having a crosslinkable functional group and containing 50 mol% or more of a 1,2-vinyl body on the basis of all structural units of polybutadiene (A)” is referred to as “polybutadiene (A)”. Sometimes abbreviated.

The present inventors can reduce the change over time of the peeling force of the release layer formed from the release agent composition with respect to the release agent composition other than the silicone-based release agent composition, and sufficiently ensure the film strength. Various studies were conducted on prescriptions for the purpose. As a result, a combination of a polybutadiene (A) having a crosslinkable functional group and containing 50 mol% or more of a 1,2-vinyl body on the basis of all structural units of the polybutadiene (A) and a melamine compound (B) is effective. I found out that it was a prescription.
Further, when an isocyanate compound is used in place of the melamine compound as the crosslinking agent, the polybutadiene has a crosslinkable functional group and contains 50 mol% or more of a 1,2-vinyl body on the basis of all the structural units of the polybutadiene (A). It was also found that the film strength could not be secured even when (A) was used.
Based on these results, the present inventors have a polybutadiene (A) having a crosslinkable functional group and containing 50 mol% or more of a 1,2-vinyl body on the basis of all structural units of the polybutadiene (A) and a melamine compound ( It has been found that a release sheet having a release agent layer formed from a release agent composition containing B) can solve the above problems, and has led to the present invention.

  In one embodiment of the present invention, the release agent composition may contain additives other than the above components (A) and (B) as long as the effects of the present invention are not impaired.

  Hereinafter, each component contained in the release agent composition will be described.

(Polybutadiene (A))
In the present invention, as the polybutadiene (A), polybutadiene having a crosslinkable functional group and containing 50 mol% or more of a 1,2-vinyl body on the basis of all structural units of polybutadiene is used.
In the present specification, the “crosslinkable functional group” means a functional group that reacts with the melamine compound (B) as a crosslinking agent.

The crosslinkable functional group possessed by the polybutadiene (A) is selected in relation to the melamine compound (B).
As a crosslinkable functional group which polybutadiene (A) has, a hydroxyl group, a carboxyl group, an epoxy group, an amino group, an isocyanate group, a thiol group, a vinyl group etc. are mentioned, for example.
Among these, from the viewpoint of making the reactivity with the melamine compound (B) better, the crosslinkable functional group is preferably a hydroxyl group.
The polybutadiene (A) may have at least one crosslinkable functional group, but preferably has two or more crosslinkable functional groups. When the polybutadiene (A) has two or more crosslinkable functional groups, these functional groups may be the same or different from each other, but are preferably the same as each other.

The position of the crosslinkable functional group that the polybutadiene (A) has is not particularly limited as long as the crosslinkable functional group can react with the melamine compound (B).
Here, in one embodiment of the present invention, from the viewpoint of increasing the distance between the cross-linking points and forming a release layer that is more excellent in releasability, at least one end of the molecular chain constituting the polymer skeleton of polybutadiene (A) It preferably has a crosslinkable functional group, more preferably has a crosslinkable functional group at both ends of the molecular chain constituting the polymer backbone of polybutadiene (A), and the main chain constituting the polymer backbone of polybutadiene (A) It is more preferable to have a crosslinkable functional group only at both ends.

Moreover, polybutadiene (A) contains 50 mol% or more of 1,2-vinyl bodies on the basis of all structural units of the polybutadiene (A).
Polybutadiene is a polymer having units of 1,4-cis, 1,4-trans, and 1,2-vinyl. Various polybutadienes having different content ratios of the respective units are commercially available. In addition, polybutadienes having different content ratios of the respective units can be synthesized by a conventional method.
In the present invention, by using polybutadiene (A) containing 50 mol% or more of 1,2-vinyl body on the basis of all the structural units of polybutadiene (A) in the release agent composition, a high initial peeling force is shown. However, it is possible to obtain a release sheet having a release layer in which the change in peel force with time is small. A polybutadiene having a 1,2-vinyl content ratio of less than 50 mol% and a high content ratio of one or both of a 1,4-cis isomer and a 1,4-trans isomer is used as a release agent composition. The peeled layer has a low initial peel force and a large change in peel force with time.
The content ratio of the 1,2-vinyl body in the polybutadiene (A) is preferably 60 mol% or more, and from the viewpoint of facilitating the synthesis of the polybutadiene (A), more preferably 70 to 90 mol%, still more preferably. Is 80-90 mol%.

The number average molecular weight ( _Mn ) of the polybutadiene (A) is preferably 1,000 to 30,000, more preferably 1,000 to 20,000, still more preferably 1,000 to 10,000, and still more preferably. 1,000 to 5,000.

The polybutadiene (A) may be a hydrogenated product. The degree of hydrogenation of the polybutadiene (A) may be partially hydrogenated or fully hydrogenated. From the viewpoint of improving the chemical stability of the peeling force of the release layer, a vinyl group is used. A partially hydrogenated product having a low residual ratio is more preferable, and a completely hydrogenated product is more preferable.
From this viewpoint, it is preferable that the polybutadiene (A) has a low bromine number. The lower the bromine value, the lower the residual ratio of vinyl groups in the polybutadiene (A), and the less the chemical change such as oxidation, the better the aging stability of the peel strength of the release layer.
Specifically, the bromine number of the hydrogenated product of polybutadiene (A) is preferably 100 g / 100 g or less, more preferably 20 g / 100 g or less, still more preferably 10 g / 100 g or less, and even more preferably 8 g / 100 g or less. is there.
The bromine number is a value measured according to JIS K 2605.
In addition, polybutadiene (A) may be used individually by 1 type, and may be used in combination of 2 or more type. For example, in one embodiment of the present invention, the polybutadiene (A) may be a mixture of a hydrogenated product and a non-hydrogenated product.

(Melamine compound (B))
The melamine compound (B) is not particularly limited as long as it is a compound that can be used as a crosslinking agent for the polybutadiene (A) and can undergo a crosslinking reaction with the crosslinking functional group of the polybutadiene (A).
When the release agent composition contains the melamine compound (B), the film strength of the release layer formed by the release agent composition can be improved. Such an effect cannot be obtained when an isocyanate compound or the like is used instead of the melamine compound.

The melamine compound (B) is preferably a methylolated melamine resin, iminomethylolated melamine resin, methylated melamine resin, ethylated melamine resin, propylated melamine resin, butylated melamine resin, hexylated melamine resin, and octylated melamine One or more selected from the group consisting of resins.
Among these, one or more selected from the group consisting of a methylolated melamine resin, an iminomethylolated melamine resin, and a methylated melamine resin is more preferable, and a methylated melamine resin is more preferable.

(Content and content ratio of polybutadiene (A) and melamine compound (B))
In one embodiment of the present invention, the total content of the polybutadiene (A) and the melamine compound (B) in the release agent composition is preferably 70% by mass or more based on the total amount (100% by mass) of the release agent composition. More preferably, it is 80 mass% or more, More preferably, it is 90 mass% or more, More preferably, it is 95 mass% or more.

In one embodiment of the present invention, from the viewpoint of further improving the temporal stability of the release layer, the content ratio (A / B) of the polybutadiene (A) to the melamine compound (B) is preferably a mass ratio, preferably 5/95. It is -95/5, More preferably, it is 10 / 90-90 / 10.
The more preferable range of the content ratio (A / B) of the polybutadiene (A) and the melamine compound (B) varies depending on the value required as the peel force from the object to be laminated. For example, when a higher peeling force is required within the range of the peeling force of the release layer obtained by the combination of the polybutadiene (A) and the melamine compound (B), the polybutadiene (A) and the melamine compound (B) A more preferable content ratio (A / B) is 5/95 to 30/70, more preferably 10/90 to 20/80 in terms of mass ratio. Conversely, when a low peel strength is required within the range of peel strength of the release layer obtained by the combination of polybutadiene (A) and melamine compound (B), the polybutadiene (A) and melamine compound (B) A more preferable content ratio (A / B) is 70/30 to 95/5, and more preferably 80/20 to 90/10 in terms of mass ratio.

(Acid catalyst)
In one embodiment of the present invention, the release agent composition may further contain an acid catalyst. By using an acid catalyst, the cross-linking reactivity between the polybutadiene (A) and the melamine compound (B) can be improved, and the aging stability of the peeling force of the release layer can be more easily improved.
Although there is no restriction | limiting in particular as an acid catalyst, For example, organic acid catalysts, such as p-toluenesulfonic acid, methanesulfonic acid, and alkyl phosphate ester, are suitable.
The above acid catalysts may be used alone or in combination of two or more.
The amount of the acid catalyst used is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and still more preferably, with respect to 100 parts by mass of the total amount of polybutadiene (A) and melamine compound (B). 1 to 5 parts by mass.

(Other additives)
In one embodiment of the present invention, the release agent composition may contain additives other than the above-described components (A) and (B) and an acid catalyst, if necessary.
Examples of such additives include various additives such as antioxidants, ultraviolet absorbers, inorganic or organic fillers, antistatic agents, surfactants, photoinitiators, and light stabilizers.

(Silicone compound)
In one embodiment of the present invention, the release agent composition preferably contains substantially no silicone compound.
If a release sheet having a release layer formed from a release agent composition containing a silicone compound is used in an electronic material, the silicone compound may migrate to the electronic component and cause corrosion or malfunction of the electronic component. It is.
In one embodiment of the present invention, the content of the silicone compound in the release agent composition is preferably less than 5.0% by mass, more preferably 2.0%, based on the total amount (100% by mass) of the release agent composition. It is less than mass%, more preferably less than 1.0 mass%, still more preferably less than 0.1 mass%, and still more preferably less than 0.01 mass%.

(Isocyanate compound)
In the present invention, as long as the release agent composition contains the melamine compound (B), other crosslinking agents may or may not be used together. It is preferable that the agent composition does not substantially contain an isocyanate compound. Isocyanate compounds are expected to react with the melamine compound (B) to form a crosslinked product when the functional group of the polybutadiene (A) is a hydroxyl group. Can not form. Moreover, when an unreacted isocyanate compound remains in the release agent layer, there is a correlation with an object to be laminated, and the peel force may increase with time.
In one embodiment of the present invention, the isocyanate compound content in the release agent composition is preferably less than 1.0% by mass, more preferably 0.1%, based on the total amount (100% by mass) of the release agent composition. It is less than mass%, more preferably less than 0.01 mass%, still more preferably less than 0.001 mass%.

(Non-reactive polyolefin)
In one embodiment of the present invention, it is preferable that the release agent composition contains substantially no non-reactive polyolefin.
In the present specification, the “non-reactive polyolefin” means a non-hydrogenated polyolefin having no crosslinkable functional group or a hydrogenated polyolefin having no crosslinkable functional group.
When the release agent composition contains the non-reactive polyolefin, there are relatively few components that are cross-linked in the release agent composition, and the film strength of the release layer can be reduced. Moreover, solvent resistance can also be reduced. Non-reactive polyolefin bleeds out and changes over time, in-process contamination, and transfer to cast resin occur.
In one embodiment of the present invention, the content of the non-reactive polyolefin in the release agent composition is preferably less than 5.0% by mass, more preferably 2 based on the total amount (100% by mass) of the release agent composition. Less than 0.0% by mass, more preferably less than 1.0% by mass, still more preferably less than 0.1% by mass, and still more preferably less than 0.01% by mass.

(Poly (meth) acrylic acid ester)
In one embodiment of the present invention, it is preferable that the release agent composition contains substantially no poly (meth) acrylic acid ester.
In the present specification, “(meth) acrylic acid” means both “acrylic acid” and “methacrylic acid”.
When the poly (meth) acrylic acid ester does not have a crosslinkable functional group, the component that crosslinks in the release agent composition is relatively reduced, and the film strength of the release layer can be reduced.
When the poly (meth) acrylic acid ester has a crosslinkable functional group, the ratio of the crosslinkable reaction product of the hydrogenated product (A) of the polyolefin having a crosslinkable functional group and the melamine compound (B) in the release agent composition is There is a fear that the stability with time of the peeling force of the release layer may be lowered. Moreover, there exists a possibility that the film | membrane intensity | strength of a peeling layer may also fall.
In one embodiment of the present invention, the content of the poly (meth) acrylic acid ester having a crosslinkable functional group in the release agent composition is preferably 5. based on the total amount (100% by mass) of the release agent composition. It is less than 0% by mass, more preferably less than 2.0% by mass, still more preferably less than 1.0% by mass, still more preferably less than 0.1% by mass, and still more preferably less than 0.01% by mass.

(Diluted solvent)
In one embodiment of the present invention, from the viewpoint of improving the coating property to the substrate, the release agent composition may be in the form of a solution by adding a diluent solvent to the various active ingredients described above.
The dilution solvent is selected from organic solvents in which the above-described components (A) and (B) have good solubility.
Examples of such an organic solvent include toluene, xylene, heptane, octane, methanol, ethanol, isopropyl alcohol, isobutanol, n-butanol, ethyl acetate, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran and the like.
These may be used alone or in combination of two or more.
In addition, the organic solvent used as a diluting solvent may use the organic solvent used at the time of the synthesis | combination of the above-mentioned component (A) and (B) as it is, or the above-mentioned so that a release agent composition can be apply | coated uniformly. You may add the organic solvent used at the time of the synthesis | combination of the component (A) and (B), and / or 1 or more types of other organic solvents.

What is necessary is just to select suitably the quantity of a dilution solvent so that it may become the quantity which has a moderate viscosity at the time of application | coating of a peeling agent composition.
Specifically, the active ingredient (solid content) concentration contained in the solution of the release agent composition is preferably 0.1 to 15% by mass, more preferably 0.2 to 10% by mass, and still more preferably 0.5. It is prepared to be in the range of ˜5% by mass.

<Thickness of release layer>
Although there is no restriction | limiting in particular in the thickness of a peeling layer, Usually, what is necessary is just 25-1000 nm, Preferably it is 50-500 nm. If the thickness of the release layer is 25 nm or more, it is possible to suppress variations in the peel force due to variations in the coating amount. Moreover, if the thickness of a peeling layer is 1000 nm or less, sclerosis | hardenability of the coating film of a releasing agent composition can be made favorable.
The thickness of the release layer is measured, for example, by the method described in Examples described later.

<Base material>
Examples of the base material used for the release sheet of the present invention include, for example, high-quality paper, clay-coated paper, cast-coated paper, kraft paper, and other paper, laminated paper obtained by laminating a thermoplastic resin such as polyethylene resin to these papers, Paper sheets such as synthetic paper, polyolefin resins such as polyethylene resin and polypropylene resin; polyester resins such as polybutylene terephthalate resin, polyethylene terephthalate resin and polyethylene naphthalate resin; polyetherimide resin; acetate resin; polystyrene resin; And a synthetic resin sheet.
The substrate may be a single layer or a multilayer of two or more layers of the same or different types.
Although there is no restriction | limiting in particular in the thickness of a base material, Usually, what is necessary is just 10-300 micrometers, Preferably it is 20-200 micrometers. If the thickness of the base material is 10 to 300 μm, for example, it is possible to give stiffness and strength suitable for performing processing such as printing, cutting, and sticking on an adhesive sheet using a release sheet.

In addition, when using a synthetic resin as the base material, the surface on which the release layer of the base material is provided is formed by a method such as an oxidation method or a concavo-convex method as desired in order to improve the adhesion between the base material and the release layer. Processing can be performed.
Examples of the oxidation method include corona discharge surface treatment, chromic acid surface treatment (wet), flame surface treatment, hot air surface treatment, ozone / ultraviolet irradiation surface treatment, and the like. Examples of the unevenness method include a sand blast method and a solvent treatment method. These surface treatment methods are appropriately selected depending on the type of substrate, but generally, the corona discharge surface treatment method is preferably used from the viewpoints of effects and operability. Moreover, primer treatment can also be performed.

In the release sheet of the present invention, the surface on the release layer side may be embossed to form irregularities on the surface of the release sheet.
In the release sheet of the present invention, other layers such as an easy adhesion layer and an antistatic layer may be provided between the substrate and the release layer. When the release sheet includes the easy-adhesion layer, it is possible to effectively prevent the release layer from falling off the release sheet.

The easy-adhesion layer is usually formed by applying an easy-adhesion coating agent on the surface of the base material on the release layer side. Examples of the easily adhesive coating agent include polyester resins, urethane resins, acrylic resins, melamine resins, oxazoline group-containing resins, carbodiimide group-containing resins, epoxy group-containing resins, isocyanate-containing resins, and copolymers thereof. Examples thereof include a coating agent mainly composed of natural rubber or synthetic rubber.
These resins may be used alone or in combination of two different types. In addition, in order to improve the applicability of the easy-adhesion coating agent to the substrate surface and the adhesion between the substrate and the easy-adhesion layer, the surface of the substrate to which the easy-adhesion coating agent is applied is subjected to chemical treatment and discharge treatment. A surface treatment such as the above may be performed.

  The thickness of the easy adhesion layer is preferably 50 nm or more, and more preferably 100 nm or more. Further, the thickness is preferably 5 μm or less, and more preferably 1 μm or less. The effect of an easily bonding layer can be acquired favorably because the said thickness is 50 nm or more. In addition, when the thickness is 5 μm or less, the slipping property of the surface of the easy-adhesive layer on the side opposite to the substrate becomes good, and the workability of applying the release agent composition on the easy-adhesive layer is good. become.

[Physical properties of release sheet]
<Change in peel force over time>
In the release sheet of one embodiment of the present invention, the rate of change in peel force before and after heating is preferably within ± 30%, more preferably within ± 25%, and even more preferably within ± 20%.
The rate of change in peel force before and after heating can be measured by the following method.
The peel strength of the release sheet after being exposed to a high temperature environment of 70 ° C. for 7 days is defined as the peel strength Y after heating.
Let the peeling force of the peeling sheet in the state without the exposure to the said high temperature environment be the initial stage peeling force X. FIG.
And from the measured post-heating peel force Y and initial peel force X, the rate of change of the peel force before and after heating can be calculated using the following equation.
Change rate of peeling force before and after heating = {(peeling force after heating Y−initial peeling force X) / initial peeling force X} × 100
The initial peeling force X is not only exposed to a high temperature environment of 70 ° C. but also exposed to other high temperature environments, and used a release sheet stored at room temperature after production. Measured.
Moreover, the initial peeling force X and the post-heating peeling force Y can be measured by the method as described in the Example mentioned later, for example. In the present invention, the rate of change in peel force within ± Z% means that the rate of change is (−Z)% or more and (+ Z)% or less.

<Peeling force>
In general, the preferable value of the release force of the release sheet varies depending on the application to be applied and the type of objects to be laminated. In some cases, a low release force is preferable so that the release operation at the time of release is smooth, or the release operation is performed. In some cases, a high peeling force is preferable in order to improve the retention of the object.
The release sheet of the present invention is preferably used when the setting of the initial release force is high.
In one embodiment of the present invention, the peeling force of the release layer exhibited by the release sheet is preferably 2500 mN / 20 mm or more, more preferably 3000 mN / 20 mm or more, and further preferably 3500 mN / 20 mm or more. In addition, the upper limit of the peeling force of the release sheet is usually preferably 6000 mN / 20 mm.
In addition, since the peeling force of a peeling sheet changes with the target objects laminated | stacked, as the evaluation method, it measures by the method as described in the Example mentioned later.

[Use of release sheet]
The release sheet of the present invention can be used as a protective sheet for various pressure-sensitive adhesive bodies such as pressure-sensitive adhesive sheets. For example, the pressure-sensitive adhesive layer side of a pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer provided on one surface of the base material. Used on the surface. It can also be used as a process film when producing various resin sheets, ceramic green sheets, synthetic leather, various composite materials and the like. When used as a process film, it is used in a process of peeling from the release sheet various sheet materials formed by casting, applying, or the like, a resin, a ceramic slurry or the like on the release layer side surface of the release sheet. In addition, the release sheet of the present invention is particularly preferably used for electronic equipment because the release layer is formed of a non-silicone release agent composition. For example, in the manufacturing process of electronic components such as relays, various switches, connectors, motors, and hard disks, it can be suitably used as a release sheet for pressure-sensitive adhesive sheets for temporary fixing during assembly of electronic components and component content display.

[Method for producing release sheet]
In the release sheet of the present invention, for example, a release agent composition is applied on at least one surface of a substrate, heat-treated, and the polybutadiene (A) and the melamine compound (B) are crosslinked to form a crosslinked layer as a release layer. It can be manufactured by forming a body.
As described above, the release agent composition may be in the form of a solution diluted with a diluent solvent.

  The heat treatment temperature is preferably from 100 to 170 ° C, more preferably from 130 to 160 ° C. The heat treatment time is not particularly limited, but is preferably 30 seconds to 5 minutes.

  Examples of the method for applying the release agent composition include a gravure coating method, a bar coating method, a spray coating method, a spin coating method, an air knife coating method, a roll coating method, a blade coating method, a gate roll coating method, and a die coating method. Can be mentioned.

  The coating thickness of the release agent composition is adjusted so that the thickness of the obtained release layer is in the above range.

  The present invention will be specifically described with reference to the following examples, but the present invention is not limited to the following examples.

  The physical property values in the following examples and comparative examples are values measured by the following methods.

[Thickness of release layer]
The thickness of the release layer was measured using a spectroscopic ellipsometer (manufactured by JA Woollam Japan, trade name: spectroscopic ellipsometry 2000U).

[Examples and Comparative Examples]
The release sheets of Examples 1 to 9 and Comparative Examples 1 to 4 were produced by the following procedure.

<Example 1>
As polybutadiene (A), polybutadiene (A1) (manufactured by Nippon Soda Co., Ltd., trade name: GI-2000, bromine number: 8 g / 100 g, solid content concentration: 100 mass%, number average molecular weight: 2,000) was used. .
Polybutadiene (A1) is a hydrogenated product of polybutadiene having hydroxyl groups only at both ends of the main chain, and the composition ratio of 1,4-cis form, 1,4-trans form, and 1,2-vinyl form (Cis / trans / 1,2-vinyl) is 0/15/85 in molar ratio.
As a crosslinking agent, hexamethoxymethylmelamine (manufactured by Nippon Cytec Industries, product name: Cymel 303 (trade name), solid content concentration: 100% by mass), which is a melamine compound, was used.
As the acid catalyst, p-toluenesulfonic acid was used.

10 parts by mass of a crosslinking agent and 2.0 parts by mass of p-toluenesulfonic acid were added to 90 parts by mass of polybutadiene (A1) to obtain a release agent composition. In addition, "mass part" here means the mass part in conversion of an active ingredient (solid content), and is the same meaning hereafter unless there is particular notice.
p-Toluenesulfonic acid was added as a solution diluted to a solid content concentration of 50% by mass using a mixed solvent of methanol and isopropyl alcohol (mass ratio 41.2: 9.4).
The obtained release agent composition was prepared by diluting the solid content concentration to 2.5% by mass using a mixed solvent of toluene and methyl ethyl ketone (mass ratio 6: 4). It was.

The coating solution of the obtained release agent composition is applied to one side of a 50 μm thick polyethylene terephthalate film (product name: Diafoil T-100, manufactured by Mitsubishi Chemical Corporation) using a Meyer bar to form a coating film did.
Subsequently, the said coating film was hardened by drying at 150 degreeC for 1 minute, the 150-nm-thick peeling layer was formed, and the peeling sheet was obtained.

<Example 2>
A release sheet was obtained in the same manner as in Example 1 except that the blending ratio of the polybutadiene (A1) and the crosslinking agent was changed and 50 parts by mass of the crosslinking agent was added to 50 parts by mass of the polybutadiene (A1). It was.

<Example 3>
A release sheet was obtained in the same manner as in Example 1 except that the blending ratio of the polybutadiene (A1) and the crosslinking agent was changed and 90 parts by mass of the crosslinking agent was added to 10 parts by mass of the polybutadiene (A1). .

<Example 4>
Instead of polybutadiene (A1), polybutadiene (A2) (manufactured by Nippon Soda Co., Ltd., trade name: GI-1000, bromine number: 7 g / 100 g, solid content concentration: 100 mass%, number average molecular weight: 1,500) A release sheet was obtained in the same manner as in Example 1 except that it was used.
Polybutadiene (A2), like polybutadiene (A1), is a hydrogenated product of polybutadiene having hydroxyl groups only at both ends of the main chain, and is a 1,4-cis isomer, 1,4-trans isomer, The component ratio (cis / trans / 1,2-vinyl) to the vinyl body is 0/15/85 in molar ratio. However, the number average molecular weight and bromine number differ from polybutadiene (A1).

<Example 5>
Instead of polybutadiene (A1), polybutadiene (A3) (manufactured by Nippon Soda Co., Ltd., trade name: GI-3000, bromine number: 13 g / 100 g, solid content concentration: 100 mass%, number average molecular weight: 3,100) A release sheet was obtained in the same manner as in Example 1 except that it was used.
Polybutadiene (A3), like polybutadiene (A1) and (A2), is a hydrogenated product of polybutadiene having hydroxyl groups only at both ends of the main chain, and is a 1,4-cis isomer, 1,4-trans isomer, The structural ratio (cis / trans / 1,2-vinyl) to the 1,2-vinyl body is 0/15/85 in molar ratio. However, the number average molecular weight and bromine number are different from those of polybutadienes (A1) and (A2).

<Example 6>
Instead of polybutadiene (A1), polybutadiene (A4) (manufactured by Nippon Soda Co., Ltd., trade name: G-1000, bromine number: 400 g / 100 g, solid content concentration: 100 mass%, number average molecular weight: 1,400) A release sheet was obtained in the same manner as in Example 1 except that it was used.
The polybutadiene (A4) is a polybutadiene having hydroxyl groups only at both ends of the main chain, like the polybutadienes (A1) to (A3), and is a 1,4-cis isomer, a 1,4-trans isomer, The component ratio (cis / trans / 1,2-vinyl) to the vinyl body is 0/15/85 in molar ratio. However, it differs from the polybutadienes (A1) to (A3) in that they are not hydrogenated. Further, the number average molecular weight and the bromine number are different.

<Example 7>
In addition to polybutadiene (A), a release sheet was obtained in the same manner as in Example 1 except that polybutadiene (A ′) different from polybutadiene (A) was blended and the blending ratio of each component was changed.
Polybutadiene (A) was polybutadiene (A1).
Polybutadiene (A ′) was polybutadiene (A4).
The blending ratio of each component was as follows.
45 parts by mass of polybutadiene (A1) was 45 parts by mass of polybutadiene (A4), 10 parts by mass of melamine compound, and 2.0 parts by mass of p-toluenesulfonic acid.

<Example 8>
The blending ratio of the polybutadiene (A1), the polybutadiene (A4), and the cross-linking agent was changed, except that the polybutadiene (A4) was 10 parts by mass and the melamine compound was 80 parts by mass with respect to 10 parts by mass of the polybutadiene (A1). A release sheet was obtained in the same manner as in Example 7.

<Example 9>
Instead of polybutadiene (A4), polybutadiene (A5) (manufactured by Idemitsu Kosan Co., Ltd., trade name: Poly bd R-45HT, bromine number: 398 g / 100 g, solid content concentration: 100 mass%, number average molecular weight: 2,800 ) Was used in the same manner as in Example 7 except that a release sheet was obtained.
Like polybutadiene (A4), polybutadiene (A5) is a polybutadiene having hydroxyl groups only at both ends of the main chain and is not hydrogenated. However, the constitutional ratio (cis / trans / 1,2-vinyl), number average molecular weight, and bromine number of 1,4-cis isomer, 1,4-trans isomer, and 1,2-vinyl isomer are different. .
The composition ratio (cis / trans / 1,2-vinyl) of the 1,4-cis isomer, 1,4-trans isomer, and 1,2-vinyl isomer of polybutadiene (A5) is 20 / 60/20.

<Comparative Example 1>
A release sheet was obtained in the same manner as in Example 1 except that polybutadiene (A5) was used instead of polybutadiene (A1).

<Comparative example 2>
Instead of polybutadiene (A1), polybutadiene (A6) (manufactured by Evonik, trade name: Polyvest 110, bromine number: 400 g / 100 g, solid content concentration: 100 mass%, number average molecular weight: 1,000) was used. Except for the above, a release sheet was obtained in the same manner as in Example 1.
Polybutadiene (A6) is a polybutadiene which has no hydroxyl group and is not hydrogenated.
The composition ratio (cis / trans / 1,2-vinyl) of the 1,4-cis isomer, 1,4-trans isomer, and 1,2-vinyl isomer of polybutadiene (A6) is a molar ratio, 75/24/1.

<Comparative Example 3>
Instead of polybutadiene (A1), polybutadiene (A7) (manufactured by Evonik, trade name: Polybest HT, bromine number: 400 g / 100 g, solid content concentration: 100 mass%, number average molecular weight: 2,900) was used. Except for the above, a release sheet was obtained in the same manner as in Example 1.
The polybutadiene (A7) is a polybutadiene having hydroxyl groups only at both ends of the main chain, as in the case of the polybutadienes (A4) and (A5), and is not hydrogenated. However, the constitutional ratio (cis / trans / 1,2-vinyl), number average molecular weight, and bromine number of 1,4-cis isomer, 1,4-trans isomer, and 1,2-vinyl isomer are different. .
The composition ratio (cis / trans / 1,2-vinyl) of the 1,4-cis isomer, 1,4-trans isomer, and 1,2-vinyl isomer of polybutadiene (A7) is 20 / 58/22.

<Comparative Example 4>
As in Example 1, except that an isocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronate L, solid content concentration: 75% by mass, diluting solvent: ethyl acetate) was used as the crosslinking agent instead of the melamine compound. A release sheet was prepared by this method.

  The following measurement and evaluation were implemented about the peeling sheet of Examples 1-9 and Comparative Examples 1-4.

[Measurement of peel force]
On the release layers of the release sheets of Examples 1 to 9 and Comparative Examples 1 to 4, a 20 mm wide adhesive tape (manufactured by Nitto Denko Corporation, product number: No. 31B) was applied using a 5 kg roller, and the release force was applied. A sample for measurement was prepared.
30 minutes after application, the obtained sample was fixed to a universal tensile testing machine (manufactured by Shimadzu Corporation, trade name: Autograph AGS-20NX), and in accordance with JIS K6854: 1999, the tensile speed was 0 in the 180 ° direction. The peel strength (mN / 20 mm) of the release sheet was measured by peeling the adhesive tape from the release layer at a rate of 3 m / min.
The measurement of peeling force with respect to the release sheets of Examples 1 to 9 and Comparative Examples 1 to 4 was performed before and after exposure to a high temperature environment of 70 ° C. for 7 days.
Then, the peel strength of the release sheet after being exposed to the high temperature environment for 7 days is defined as the peel strength after heating Y, and the peel strength of the release sheet in the state without exposure to the high temperature environment is defined as the initial peel force X. The rate of change in peel force before and after heating was determined using the formula.
Change rate of peeling force before and after heating = {(peeling force after heating Y−initial peeling force X) / initial peeling force X} × 100

[Evaluation of solvent resistance]
A non-woven fabric impregnated with methyl ethyl ketone (trade name: Bem Cotton) impregnated with methyl ethyl ketone is placed on the release layers of the release sheets of Examples 1 to 9 and Comparative Examples 1 to 4, and a load of 100 g from above is applied 5 times. Wiped out. The surface of the release layer was visually observed, and the case where there was no change on the surface of the release layer was evaluated as ◯, and the case where the surface of the release layer was whitened by scratches was evaluated as x.

The results are shown in Table 1.
In Table 1, “Bd—H” described in the composition column means a hydrogenated product of polybutadiene, and “Bd” means an unhydrogenated product of polybutadiene.
In Table 1, “OH” described in the functional group column means polybutadiene having hydroxyl groups only at both ends of the main chain, and “none” means polybutadiene having no hydroxyl groups. .

Table 1 shows the following.
Example having a release layer formed from a release agent composition having a crosslinkable functional group and containing a polybutadiene (A) containing 50 mol% or more of a 1,2-vinyl body on the basis of all structural units of polybutadiene and a melamine compound. It can be seen that the release sheets 1 to 9 have a very small change in peel force before and after heating, and the rate of change in peel force before and after heating is within ± 30%. Moreover, it turns out that the peeling layer of the peeling sheet of Examples 1-9 is excellent also in solvent resistance.
Furthermore, the release sheets of Examples 1 to 9 have a peel strength of 2500 mN / 20 mm or more both before and after heating, and have excellent temporal stability at high temperatures even if the initial peel force is a high value. I understand.
In contrast, the release sheets of Comparative Examples 1 to 3 using polybutadiene having a 1,2-vinyl body content ratio of less than 50 mol% based on the total constituent units of polybutadiene have a very large change in peeling force before and after heating. Thus, it can be seen that the peel strength increases significantly after heating.
Moreover, it replaced with the polybutadiene (A) which has a crosslinkable functional group, the peeling sheet of the comparative example 2 using the polybutadiene which does not have a crosslinkable functional group, and the comparative example 4 which replaced with the melamine compound and used the isocyanate compound. It can be seen that the release layer of this example has insufficient solvent resistance as compared with the release layers of the release sheets of Examples 1 to 9, and the film strength is inferior to the extent that the evaluation of the release force becomes impossible.

1 Release sheet 10 Base material 11 Release layer

Claims (5)

A release sheet having a substrate and a release layer,
The release layer is a layer formed from a release agent composition containing a polybutadiene (A) having a crosslinkable functional group and a melamine compound (B),
The crosslinkable functional group is a functional group that reacts with the melamine compound (B),
The release sheet, wherein the polybutadiene (A) having a crosslinkable functional group contains 50 mol% or more of a 1,2-vinyl body based on the total constituent units of the polybutadiene (A).   The release sheet according to claim 1, wherein the crosslinkable functional group is a hydroxyl group.   The release sheet according to claim 1 or 2, wherein the polybutadiene (A) having a crosslinkable functional group is a hydrogenated product having a bromine number of 10 g / 100 g or less.   The peel strength of the release sheet after being exposed to a high temperature environment of 70 ° C. for 7 days is defined as the peel strength after heating Y, and the peel strength of the release sheet in the state without exposure to the high temperature environment is the initial peel force X. The change rate represented by {(peeling force after heating Y−initial peel force X) / initial peel force X} × 100 is within ± 30%. The release sheet according to item.   The peeling sheet as described in any one of Claims 1-4 whose peeling force at the time of peeling from an adhesive layer is 2500 mN / 20mm or more.