JP2005154689A - Pressure sensitive adhesive sheet with separator, optical member-assembling body, and method for assembling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a pressure sensitive adhesive sheet, excellent in transparency, hardly generating appearance defects such as bubble-contamination, linear streak, excellent in pasting workability and further produced at a low cost, and to provide an optical member-assembling body and a method for assembling the same. <P>SOLUTION: The pressure sensitive type adhesive sheet with a separator is prepared by installing a pressure sensitive adhesive layer for pasting an optical member at a one side surface of a plastic separator, further making it in a rolled state, and by contacting another surface of the separator, with the pressure sensitive type adhesive layer while having ≤0.1 μm surface roughness Ra of both surfaces of the plastic separator making a contact with the pressure sensitive type adhesive layer, and also while keeping ≥10 mN/25 mm difference in peeling strengths between both of the surfaces of the plastic separator from the pressure sensitive type adhesive layer and ≥80% total light transmittance of the pressure sensitive type adhesive layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a pressure-sensitive adhesive sheet with a separator, an optical member assembly, and an assembling method thereof, and is particularly used when laminating a plate-like or sheet-like optical member. The present invention relates to a pressure-sensitive adhesive sheet that hardly causes appearance defects such as traces and streaks, is excellent in pasting workability, and can be manufactured at low cost.

  A variety of plate-like and sheet-like optical members are used in display products such as a liquid crystal display (LCD), a plasma display (PDP), a projection screen (PJ), and a cathode ray tube (CRT). These optical members are bonded to each other with a transparent adhesive for the purpose of reducing the optical loss due to light scattering between the optical members, increasing the efficiency during product assembly, and maintaining the strength of the product. Things have been done. For example, for LCDs, the polarizing plate and the liquid crystal cell are bonded, for the anti-reflection (AR) film and the polarizing plate, for the PDP, an AR film, an electromagnetic shielding film, a near infrared absorption (NIR) film, etc., for the CRT, an AR film, Adhesion between an anti-glare (AG) film and a cathode ray tube is performed.

  As such adhesives, pressure-sensitive adhesives, heat-sensitive adhesives, ultraviolet (UV) curable adhesives, and the like have been developed, but pressure-sensitive adhesives that require relatively little capital investment for application are available. Most widely used.

  In addition, as a method of forming an adhesive layer on the surface of the optical member, a method in which a liquid adhesive is directly applied to the surface of the optical member and an adhesive sheet previously formed on a separator film are laminated and transferred to the surface of the optical member. There is a way. The method of directly applying a liquid adhesive, although the adhesive itself is inexpensive, contaminates the work environment during the application work (especially when applying an organic solvent type adhesive, an organic solvent countermeasure is required) There are problems that it is difficult to form an adhesive layer with good thickness accuracy and that the optical member is easily damaged due to the application of a liquid adhesive. On the other hand, the method of laminating and transferring the adhesive sheet is relatively expensive and the cost is likely to be higher than the method of direct application, but there is little contamination of the working environment and no large equipment is required for bonding. There are also features such as, are used properly according to the features of the two methods.

  As a pressure-sensitive adhesive sheet used for such applications, an adhesive sheet in which a pressure-sensitive adhesive layer is formed between two plastic separators is generally used. However, due to the recent improvement in display display accuracy, the adhesive sheet has excellent transparency, has very few appearance defects such as air bubbles and adhesive layer deformation when bonded to an optical member, and can be manufactured at low cost. Is required.

  The present invention eliminates the drawbacks described in the prior art, is excellent in transparency, hardly causes appearance defects such as air bubbles and streak marks at the time of pasting, is superior in pasting workability, and more inexpensive. It is an object of the present invention to provide a pressure-sensitive adhesive sheet with a separator, an optical member assembly, and a method for assembling the separator.

The present invention provides a pressure-sensitive adhesive sheet with a separator in which a pressure-sensitive adhesive layer for bonding an optical member is provided on one side of a plastic separator, and the pressure-sensitive adhesive layer contacts the other side of the plastic separator. The surface roughness Ra of both surfaces in contact with the pressure-sensitive adhesive layer of the plastic separator is both 0.1 μm or less, and the difference in peeling force from the pressure-sensitive adhesive layer of the double-sided plastic separator is 10 mN / 25 mm or more. The pressure-sensitive adhesive sheet with a separator is characterized in that the total light transmittance of the pressure-sensitive adhesive layer is 80% or more.
Moreover, this invention is a pressure sensitive adhesive sheet with a separator whose peeling force from the pressure sensitive adhesive layer of the said plastic separator is 200 mN / 25mm or less.
And this invention is a pressure sensitive adhesive sheet with a separator whose adhesive force to the acrylic board of the said pressure sensitive adhesive layer is 1 N / 25mm or more.
Furthermore, the present invention is a pressure-sensitive adhesive sheet with a separator whose adhesive layer is a cross-linked acrylic adhesive.
Moreover, this invention is a pressure-sensitive adhesive sheet with a separator formed by providing the part which does not have an adhesive bond layer of 1 mm-50 mm in the width | variety both end surfaces.
And this invention is the optical member assembly which bonded and assembled the optical member, Comprising: The optical member adhere | attached by the pressure sensitive adhesive layer which peeled the plastic separator of both surfaces of said pressure sensitive adhesive sheet with a separator It is an assembly.
Furthermore, the present invention is a method for assembling an optical member assembly in which an optical member is bonded to the pressure-sensitive adhesive layer obtained by peeling a plastic separator having a weak peeling force from the pressure-sensitive adhesive sheet with the separator, and a second method. This is an assembling method of an optical member assembly that is assembled by bonding an optical member.

According to the present invention, the pressure-sensitive adhesive sheet and the optical member assembly are excellent in transparency, hardly cause appearance defects such as air bubbles and streak marks at the time of application, have excellent application workability, and can be manufactured at low cost. Can be obtained.

  The pressure-sensitive adhesive sheet with a separator of the present invention is a form in which a pressure-sensitive adhesive layer is provided on one side of a plastic separator, and is further formed in a roll shape so that the pressure-sensitive adhesive layer is in contact with the other side of the plastic separator. Compared to an adhesive sheet in which a pressure-sensitive adhesive layer is formed between two plastic separators, which is a general configuration, the number of plastic separators used is one and manufacturing costs can be reduced.

  The pressure-sensitive adhesive sheet with a separator of the present invention has high transparency and a total light transmittance of 80% or more. More preferably, it is 90% or more. When the total light transmittance is lower than 80%, the light transmittance when the optical member is bonded is poor, and there arises a problem that the display becomes dark or the contrast is lowered. The total light transmittance here was measured with an integrating sphere turbidimeter (Nippon Denshoku Industries Co., Ltd., NDH2000) in accordance with JIS-K7105 with the plastic separator peeled off and only the adhesive layer.

The adhesive layer in the pressure-sensitive adhesive sheet with a separator of the present invention is a pressure-sensitive adhesive, and has an adhesive force of 1 N / 25 mm or more when attached to an acrylic plate. If it is less than 1 N / 25 mm, sufficient adhesion to the optical member cannot be obtained, causing problems such as peeling. The adhesive force with respect to an acrylic board here is the speed | rate of 2 m / min using the rubber roll which applied the pressure 5880 N / m to the acrylic board (Sumitomo Chemical Industries Sumipec E000, thickness 1.5mm flat board) for the unwound adhesive sheet. Pasting, peeling off the plastic separator and pasting a 25 μm PET film (Unit-25 S-25) under the same conditions to prepare a test piece, and leaving it at room temperature for 30 minutes, then peeling angle 180 degrees, peeling speed 0.3 m / min The value obtained by measuring the adhesive strength at room temperature.

As this pressure-sensitive adhesive, acrylic adhesives obtained by copolymerizing various acrylic monomers, natural rubber adhesives, polyisobutylene, butyl rubber, styrene-butylene-styrene copolymers (commonly used as adhesives) Synthetic rubber adhesives such as SBS), ethylene-vinyl acetate copolymer (EVA) adhesives, and mixed adhesives thereof can be used. Among these, a cross-linked acrylic adhesive is preferably used because it is easy to obtain a highly transparent adhesive such that the total light transmittance of the adhesive sheet is 80% or more.

This cross-linked acrylic adhesive is mainly composed of a low Tg monomer such as butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylamide, acrylonitrile, etc. It can be obtained by crosslinking an acrylic copolymer obtained by copolymerization with a functional group monomer with a crosslinking agent.
As this acrylic copolymer, those having a weight average molecular weight in the range of 100,000 to 1,500,000 are preferably used. If the weight average molecular weight is less than 100,000, the amount of low molecular weight substances in the adhesive increases, so the cohesive force of the adhesive tends to be low, and problems such as peeling are likely to occur when the optical member is bonded. Further, when the weight average molecular weight exceeds 1,500,000, there is a problem that the viscosity when dissolved in a solvent is high, and it is difficult to obtain a smooth adhesive coating appearance when formed into an adhesive sheet. The glass transition point (Tg) of this acrylic copolymer is preferably -20 ° C or lower. If the Tg is higher than −20 ° C., the adhesive becomes hard, and an appropriate adhesive force to the optical member cannot be obtained even if it is pressure-bonded at room temperature.

  As this crosslinking agent, known crosslinking agents such as isocyanate, melamine, and epoxy can be used. In addition, as this crosslinking agent, a polyfunctional crosslinking agent such as trifunctional or tetrafunctional is more preferably used in order to form a network structure that gently spreads in the adhesive.

  In addition, an appropriate amount of a tackifier, an antioxidant, an ultraviolet absorber, a softener, a filler and the like may be added to the adhesive layer as necessary.

  As for the thickness of the adhesive bond layer in this invention, 5-100 micrometers is preferable normally. More preferably, it is 10-50 micrometers. When the thickness is less than 5 μm, it is impossible to follow the unevenness on the surface of the optical member and a sufficient adhesive force cannot be obtained. On the other hand, when the thickness is larger than 100 μm, problems such as an increase in price per unit area and a decrease in transparency due to the thickness occur.

  The difference in peel force from the adhesive layers on both sides of the plastic separator used in the present invention is 10 mN / 25 mm or more. When the adhesive sheet is less than 10 mN / 25 mm, when the adhesive sheet is applied to the optical member, the adhesive layer adheres to the surface on which the adhesive layer of the plastic separator is to be peeled off and is placed on the plastic separator. The phenomenon that the adhesive layer in a smooth and good appearance does not remain (crying phenomenon) occurs. When this tear-off phenomenon occurs, the adhesive layer cannot be applied smoothly to the optical member, and the optical member cannot be attached with good appearance.

Moreover, the peeling force from the adhesive layers on both sides of the plastic separator used in the present invention is 200 mN / 25 mm or less. If the peeling force is higher than 200 mN / 25 mm, the unwinding workability from the roll shape and the peeling workability of the separator deteriorate, the plastic separator cannot be smoothly peeled off, and it is folded into the adhesive layer and wrinkles or steps on the surface of the adhesive layer Occurs, the deformation remains when it is attached to the optical member, resulting in an appearance defect, and bubbles are likely to be mixed during the attachment. The peeling force here is a value measured at room temperature at a peeling angle of 180 degrees, a peeling speed of 1 m / min.
Both surface roughness Ra of the plastic separator used for this invention which contacted the pressure sensitive adhesive is 0.1 micrometer or less. When the surface roughness Ra is larger than 0.1 μm, the roughness of the separator surface is transferred to the adhesive layer, the adhesive layer surface becomes rough, and bubbles are likely to be mixed during bonding. The surface roughness here is centerline average roughness (Ra) measured with a contact-type surface roughness meter (for example, measuring device SE-3C, analysis device AY-22, manufactured by Kosaka Laboratory Ltd.) or JIS B 0601. (1994) or JIS B 0601 (2001) means arithmetic mean roughness (Ra).
Examples of the material for the plastic separator include polyester film, polypropylene film, polyethylene film, polycarbonate film, polystyrene film, and triacetyl cellulose film. Among these, a biaxially stretched polyester film that is easy to obtain a smooth surface and excellent in productivity can be preferably used.
Moreover, the mold release agent process is performed on both surfaces which contact | connect the adhesive bond layer of this plastic separator. Examples of the releasing agent include simple substances such as silicone resins, fluororesins, polyvinyl alcohol resins, and resins having an alkyl group, modified products, and mixtures. Among them, a silicone resin that can easily be easily peeled off from the adhesive layer can be preferably used. Particularly, a silicone resin cured by heat, ultraviolet rays, electron beams, etc. can transfer the silicone resin to the adhesive layer. It can be more preferably used for the reason of few.
The thickness of the plastic separator is preferably 10 to 200 μm. More preferably, it is 20-75 micrometers. If the thickness is less than 10 μm, the film strength is insufficient, and problems such as tearing of the film during the production of the adhesive sheet, and easy wrinkling occur. On the other hand, if it is thicker than 200 μm, the film itself becomes expensive.

  In the pressure-sensitive adhesive sheet with a separator of the present invention, it is preferable to provide a portion having no adhesive layer of 1 mm to 50 mm on both end faces of the width. If the adhesive layer is provided on the entire surface up to the end of the plastic separator, the adhesive layer adheres to the peeled end surface of the plastic separator when unrolled from the roll, and the other plastic separator surface is smooth and has a good appearance. The phenomenon that the adhesive in the state does not remain (crying separation phenomenon) occurs. When this tear-off phenomenon occurs, the adhesive layer cannot be applied smoothly to the optical member, and the optical member cannot be attached with good appearance. In addition, when a portion having no adhesive layer larger than 50 mm is provided on both end faces of the width, a phenomenon in which the plastic separator is peeled off from the end portion due to increased distortion in a portion where there is no adhesive layer when the roll is formed ( Tunneling phenomenon) is likely to occur.

  When this tunneling phenomenon occurs, the concavo-convex shape from which the plastic separator is peeled off is transferred to the adhesive layer, and when it is bonded to the optical member, the shape remains, resulting in an appearance defect. If it is 50 mm or less, the distortion at the part where there is no adhesive layer and the part where it is made into a roll is small, and the phenomenon (tunneling phenomenon) in which the plastic separator peels from the end part becomes difficult to occur.

As a method for forming the pressure-sensitive adhesive layer, known methods such as a method of applying an adhesive whose viscosity is adjusted by dissolving in an organic solvent, a method of melting and applying an adhesive, and a method of dispersing and applying in water are used. Although it can be used, as a method for forming a cross-linked acrylic adhesive, a method of applying an adhesive having a viscosity adjusted by dissolving in an organic solvent is common.
Furthermore, this plastic separator is subjected to surface treatment such as corona treatment or plasma treatment or application of a primer (primer) to improve the adhesion of the release agent layer to the surface of the plastic film as necessary. Also good. Moreover, you may apply | coat an antistatic agent in order to prevent static electricity generation as needed. Examples of the antistatic agent here include various cationic antistatic agents having a cationic group such as a quaternary ammonium salt, a pyridinium salt, and a primary to tertiary amino group, a sulfonate group, a sulfate ester base, and phosphorus. Anionic antistatic agents having an anionic group such as acid ester base and sulfonate group, amphoteric antistatic agents such as amino acid and aminosulfate ester, nonionic antistatic agents such as amino alcohol, glycerin and polyethylene glycol Examples thereof include various antistatic agents such as an agent, and polymer antistatic agents obtained by increasing the molecular weight of these antistatic agents.

An acrylic copolymer using butyl acrylate as the main monomer and acrylic acid and methacrylic acid as the functional group monomers was synthesized by a solution polymerization method. The synthesized acrylic copolymer had a weight average molecular weight of 400,000.
An adhesive solution containing 0.1 part by weight of an epoxy-based cross-linking agent is prepared with respect to 100 parts by weight of this acrylic copolymer, and heat having different peeling forces on both sides of a biaxially stretched polyester film having a thickness of 25 μm and a width of 400 mm. The separator coated with the curable silicone resin release agent was coated and dried on the heavy release release agent treated surface of the separator so that the thickness of the adhesive when dried was 40 μm, and wound into a roll. This adhesive sheet was allowed to stand at room temperature for 1 week and sufficiently aged, and then used for the test.
The peeling force from the adhesive layer of the separator coated with the adhesive in this adhesive sheet is 75 mN / 25 mm, and the peeling force from the adhesive layer on the other side (back surface) of the separator is 42 mN / It was 25 mm. Moreover, the result of measuring the surface roughness of the separator was both 0.05 μm.

An adhesive sheet was produced in the same manner as in Example 1 except that the release property of the release agent-treated surface of the separator coated with the adhesive was slightly increased.
In addition, the peeling force from the adhesive bond layer of the separator which apply | coated the adhesive agent in this adhesive sheet was 118 mN / 25mm.

Comparative Example 1
An adhesive sheet was produced in the same manner as in Example 1 except that the releasability on both sides of the separator was the same.
The peeling force from the adhesive layer of the separator coated with the adhesive in this adhesive sheet is 48 mN / 25 mm, and the peeling force from the adhesive layer on the other side (back surface) of the separator is 42 mN / It was 25 mm.

Comparative Example 2
An adhesive sheet was produced in the same manner as in Example 1 except that the release property of the release agent-treated surface of the separator coated with the adhesive was increased.
In addition, the peeling force from the adhesive bond layer of the separator which apply | coated the adhesive agent in this adhesive sheet was 490 mN / 25mm.

Comparative Example 3
An adhesive sheet was produced in the same manner as in Example 1 except that a biaxially stretched polypropylene film was used as the separator base film.
The peeling force from the adhesive layer of the separator coated with the adhesive in this adhesive sheet is 89 mN / 25 mm, and the peeling force from the adhesive layer on the other side (back surface) of the separator is 52 mN / It was 25 mm. The result of measuring the surface roughness of the separator was 0.30 μm.
The characteristic values of the adhesive sheets of the above examples and comparative examples were measured by the following methods. The results are summarized in Table 1.

（１）全光線透過率
全光線透過率は、２枚のプラスチックセパレータを剥がし接着剤層のみの状態で、積分球式濁度計（日本電色工業株式会社製、ＮＤＨ２０００型）を用いて、ＪＩＳ−Ｋ７１０５に順じて測定した。
（２）対アクリル板接着力
一方のプラスチックセパレータを剥がした接着シートをアクリル板（住友化学工業製スミペックＥ０００、厚み１．５ｍｍフラット板）に圧力５８８０Ｎ／ｍをかけたゴムロールを用い２ｍ／分の速度で貼付け、更にもう一方のプラスチックセパレータを剥がし同様の条件にて２５μｍＰＥＴフィルム（ユニチカ製Ｓ−２５）を貼付けて試験片を作製し、更に３０分間室温で放置し、その後、剥離角度１８０度、剥離速度０．３ｍ／分、室温にて接着力（Ｎ／２５ｍｍ）を測定した。
（３）セパレータの剥離力
接着シートを２５ｍｍ幅に切断し、粘着剤層からプラスチックセパレータを剥離角度１８０度、剥離速度１ｍ／分、室温雰囲気下で剥がす時の剥離力（ｍＮ／２５ｍｍ）を測定した。
（４）貼り合わせ作業性
巻物から巻出した接着シートを、大きさ２００ｍｍ×３００ｍｍのアクリル板（住友化学工業製スミペックＥ０００、厚み１．５ｍｍフラット板）に圧力５８８０Ｎ／ｍをかけたゴムロールを用い２ｍ／分の速度で貼付けた。更にもう一方のプラスチックセパレータを剥がし、５０μｍＰＥＴフィルム（ユニチカ製Ｓ−５０）を同様の条件にてラミネートした。
このときの貼り合わせ作業性を、以下の基準で評価した。
：巻物から容易に巻出すことができ、貼り合わせ作業が容易にできた。
× ：巻物から巻出し時に泣き別れ現象が発生し、貼り合わせ作業性ができなかった。
（５）貼り合わせ外観
貼り合わせ作業性を評価した試験片の外観を確認し、以下の基準で評価した。
：気泡の混入や接着剤層の変形跡等がみられず外観が良好であった。
× ：気泡の混入や接着剤層の変形跡等の外観欠陥が観察された。
− ：貼り合わせ作業ができす、外観を確認できなかった。
表１から明らかなように、本発明の接着シートである実施例１〜２は、貼り合わせ作業性に優れ、また、貼り合わせた試験片の外観も良好であった。
それに対し、プラスチックセパレータの両面の離型性を同じにした比較例１はセパレータ剥離時に泣き別れ現象が発生し、貼り合わせ作業性が悪かった。また、接着剤を塗工したセパレターの離型剤処理面からの剥離力が４９０ｍＮ／２５ｍｍと高い比較例２は、アクリル板に貼り合わせた後のセパレータの剥離がスムーズにできない為に接着剤表面に段差が発生し、貼り合わせた試験片にも接着剤層の変形による外観異常が観察された。また、セパレータの表面粗さＲａが０．３μｍと大きい比較例３では、接着剤層に粗さが転写し、貼り合わせた試験片に気泡混入が観察された。

(1) Total light transmittance The total light transmittance is measured using an integrating sphere turbidimeter (NDH2000 model, manufactured by Nippon Denshoku Industries Co., Ltd.) with only two adhesive separators peeled off. It measured according to JIS-K7105.
(2) Adhesive strength against acrylic plate 2 m / min using a rubber roll with a pressure of 5880 N / m applied to an acrylic plate (Sumipec E000 manufactured by Sumitomo Chemical Co., Ltd., thickness 1.5 mm flat plate) after peeling off one plastic separator At a speed, the other plastic separator was peeled off, and a 25 μm PET film (S-25 manufactured by Unitika) was attached under the same conditions to prepare a test piece. The test piece was further left at room temperature for 30 minutes, and then the peeling angle was 180 degrees. The adhesive force (N / 25 mm) was measured at a peeling speed of 0.3 m / min at room temperature.
(3) Separation force of the separator The adhesive sheet is cut to a width of 25 mm, and the peeling force (mN / 25 mm) when the plastic separator is peeled from the adhesive layer at a peeling angle of 180 degrees, a peeling speed of 1 m / min at room temperature is measured. did.
(4) Bonding workability A rubber roll in which a pressure of 5880 N / m is applied to an acrylic sheet (Sumitomo Chemical Industries Sumipec E000, thickness 1.5 mm flat plate) having a size of 200 mm × 300 mm is used. Affixed at a speed of 2 m / min. The other plastic separator was peeled off, and a 50 μm PET film (S-50 manufactured by Unitika) was laminated under the same conditions.
The bonding workability at this time was evaluated according to the following criteria.
: Can be easily unwound from the scroll, and can be easily bonded.
X: Peeling phenomenon occurred when unwinding from the scroll, and the bonding workability could not be achieved.
(5) Bonding appearance The appearance of the test piece evaluated for bonding workability was confirmed and evaluated according to the following criteria.
: Appearance was good with no mixing of bubbles or deformation marks of the adhesive layer.
X: Appearance defects such as bubbles and deformation marks of the adhesive layer were observed.
-: The pasting work can be performed, but the appearance cannot be confirmed.
As is clear from Table 1, Examples 1 and 2 which are adhesive sheets of the present invention were excellent in bonding workability, and the appearance of the bonded test pieces was also good.
On the other hand, in Comparative Example 1 in which the releasability on both sides of the plastic separator was the same, a tearing phenomenon occurred when the separator was peeled off, and the bonding workability was poor. In addition, Comparative Example 2 in which the separation force from the release agent-treated surface of the separator coated with adhesive is as high as 490 mN / 25 mm is because the separator cannot be smoothly peeled off after being bonded to the acrylic plate. A difference in level was observed in the specimen, and abnormal appearance due to deformation of the adhesive layer was also observed in the bonded specimens. Further, in Comparative Example 3 where the surface roughness Ra of the separator was as large as 0.3 μm, the roughness was transferred to the adhesive layer, and bubble mixing was observed in the bonded test piece.

Claims (7)

In the pressure-sensitive adhesive sheet with a separator, the pressure-sensitive adhesive layer for bonding the optical member is provided on one side of the plastic separator, and the pressure-sensitive adhesive layer is in a roll shape and the pressure-sensitive adhesive layer contacts the other side of the plastic separator. The surface roughness Ra on both sides in contact with the pressure-sensitive adhesive layer is 0.1 μm or less, and the difference in peel force from the pressure-sensitive adhesive layer of the double-sided plastic separator is 10 mN / 25 mm or more, and A pressure-sensitive adhesive sheet with a separator, wherein the pressure-sensitive adhesive layer has a total light transmittance of 80% or more. 2. The pressure-sensitive adhesive sheet with a separator according to claim 1, wherein the peeling force of the plastic separator from the pressure-sensitive adhesive layer is 200 mN / 25 mm or less. The pressure-sensitive adhesive sheet with a separator according to claim 1 or 2, wherein an adhesive force of the pressure-sensitive adhesive layer to the acrylic plate is 1 N / 25 mm or more. The pressure-sensitive adhesive sheet with a separator according to any one of claims 1 to 3, wherein the adhesive layer is a cross-linked acrylic adhesive. The pressure-sensitive adhesive sheet with a separator according to any one of claims 1 to 4, wherein portions having no adhesive layer of 1 mm to 50 mm are provided on both end faces of the width. An optical member assembly assembled by bonding optical members, and bonded by a pressure-sensitive adhesive layer from which the plastic separators on both sides of the pressure-sensitive adhesive sheet with a separator according to any one of claims 1 to 5 are peeled off. An optical member assembly, wherein A method for assembling an optical member assembly in which optical members are bonded to each other, wherein the pressure-sensitive adhesive is a pressure-sensitive adhesive sheet with a separator having a weak peeling force. A method of assembling an optical member assembly, comprising assembling a layer and a second optical member by bonding.