KR20120084250A - Heat-peelable adhesive sheet - Google Patents

Abstract

PURPOSE: A heat-releasable adhesive sheet is provided to enhance initial tackiness, shelf life, release properties after heating and cutting accuracy. CONSTITUTION: A heat-releasable adhesive sheet comprises adhesive composition layers(2) on a single side or both sides of a sheet substrate(1). The adhesive composition layer is composed of a layer using adhesive macromolecule, thermal expandable corpuscle and a cross-linking agent as a main component on a first layer(2a), and a low-polar resin layer on a second layer(2b). The adhesive composition layer is formed by laminating the low polarity resin layer of the second layer on the first resin layer surface. The adhesive composition layer has a thickness of 5 - 100 microns.

Description

Heat-peelable Adhesive Sheet {HEAT-PEELABLE ADHESIVE SHEET}

The present invention relates to a heat-peelable pressure-sensitive adhesive sheet that can be easily peeled from the adherend after being adhered to a highly polar adherend such as a ceramic green sheet and then heated for a short time.

Conventionally, after being adhered to an adherend, it is an adhesive sheet that cannot be peeled off before heating, and after heating, the thermally expandable fine particles contained in the adhesive layer expand, reduce the contact area with the adherend, and can easily peel off from the adherend. A heat-peelable pressure-sensitive adhesive sheet has been proposed.

As such a heat-peelable pressure-sensitive adhesive sheet, for example, as disclosed in Japanese Patent No. 3810911, the pressure-sensitive adhesive layer containing thermally expandable fine particles is formed on one side or both sides of the base material. Thermally expansible microparticles | fine-particles have an average particle diameter of 18 micrometers or more, and the thing in which 90% or more made the particle diameter of 10 micrometers or more exists.

The conventional heat-peelable pressure-sensitive adhesive sheet may be difficult to peel from the adherend when peeling is required after cutting the adherend to a highly polar adherend, and its improvement has been desired.

In the conventional heat-peelable pressure-sensitive adhesive sheet, since the particle diameter of the thermally expandable fine particles used is large, the thickness of the pressure-sensitive adhesive layer inevitably becomes thick. However, by increasing the thickness, especially when cutting ceramic green sheets such as multilayer ceramic capacitors and multilayer chip inductors, the cutting accuracy is reduced due to small fragmentation and the yield is lowered. Thus, this problem is solved. There has been a strong demand for the development of materials and processes.

Therefore, an object of the present invention is to solve the problems of the conventional heat-peelable pressure-sensitive adhesive sheet and to provide a heat-peelable pressure-sensitive adhesive sheet excellent in initial adhesive strength, self-peeling after heating, and cutting accuracy.

The heat-peelable pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive composition layer on one or both sides of the sheet base material, and the pressure-sensitive adhesive composition layer has a pressure-sensitive adhesive polymer, thermally expandable fine particles and a crosslinking agent as a main component on the first layer from the sheet substrate side. The second layer is formed of a low polar resin layer.

In the present invention, the pressure-sensitive adhesive composition layer is interspersed with the low-polar resin layer of the second layer on the surface of the first layer of the resin layer.

In this invention, the said adhesive composition layer is supposed to coat | cover the said 2nd low polar resin layer in the form of spot on the surface of the said 1st layer.

In this invention, the said adhesive composition layer shall be 5 micrometers-100 micrometers in thickness.

In this invention, the said thermally expansible microparticles | fine-particles are assumed to have an average particle diameter smaller than 18 micrometers.

In the present invention, the low polar resin layer has a thickness of 0.01 μm to 50 μm.

In the present invention, the low polar resin layer has a contact angle of 97.5 ° or more.

In the present invention, the low polar resin layer has an olefin resin and a surfactant as main components.

In the present invention, in the low polar resin layer, the olefin resin is in a fine particle state, and the average particle diameter of the particles is in the range of 0.01 µm to 10 µm.

Since the heat-peelable pressure-sensitive adhesive sheet of the present invention is constituted as described above, the pressure-sensitive adhesive does not remain on the adherend, and the initial adhesive force, the storage (storage) life, and the peeling property after heating are excellent. .

1 is a schematic cross-sectional view showing an example of the heat-peelable pressure-sensitive adhesive sheet of the present invention.
2 is a micrograph (400 times) showing a state in which the second layer covers the first layer of the pressure-sensitive adhesive composition layer of the heat-peelable pressure-sensitive adhesive sheet of the present invention.
3 is a micrograph (1000 times) showing a state in which the second layer covers the first layer of the pressure-sensitive adhesive composition layer of the heat-peelable pressure-sensitive adhesive sheet of the present invention.
4A, 4B and 4C are explanatory views showing the heat peeling state of the heat-peelable pressure-sensitive adhesive sheet of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the heat-peelable adhesive sheet of this invention is demonstrated based on drawing.

The heat-peelable pressure-sensitive adhesive sheet of the present invention has the pressure-sensitive adhesive composition layer 2 on one side or both sides (one side in the figure) of the sheet base material 1 as shown in FIG. The separator 3 is provided in the surface of the layer 2 as needed.

The pressure-sensitive adhesive composition layer 2 is formed of a resin layer containing a tacky polymer, thermally expandable fine particles and a crosslinking agent as a main component from the sheet base material 1 side, and the second layer (2b) has a low polarity number. It is formed as a strata. Thus, what thermally expandable microparticles | fine-particles are contained in the 1st layer, and what forms the low polar resin layer in the 2nd layer did not exist until now.

Thus, the heat-peelable pressure-sensitive adhesive sheet of the present invention generates irregularities by heating together with the low-polar resin layer of the second layer (2b) by expanding the thermally expandable fine particles of the first layer (2a) by heating when peeling is required. It is supposed to make it easy to peel from an adherend.

In the present invention, the sheet base material may be a plastic film such as a polyester film, a woven fabric, a nonwoven fabric, a paper, a metal foil, a foam sheet, or the like, and the shape is arbitrary, such as a strip, and the thickness is 5 µm to 500 µm. It is preferable to set it as micrometer-200 micrometers, and it is more preferable to set it as 10 micrometers-100 micrometers. In this case, even if the thickness of the said sheet base material is smaller than 5 micrometers and larger than 500 micrometers, there is no problem in a characteristic, but it is not preferable in the preparation process of an adhesive sheet.

In the present invention, the adhesive polymer is made of methacrylic or acrylic adhesive polymer, and the weight average molecular weight is 100,000 to 2 million, but preferably 500,000 to 1.5 million, more preferably 1 million to 1.5 million. Do. If the weight average molecular weight of the pressure-sensitive adhesive polymer is less than 100,000, it is not preferable because a full mark of the pressure-sensitive adhesive after heating occurs, and if the weight average molecular weight of the pressure-sensitive adhesive polymer exceeds 2 million, acrylic and methacrylic acid pressure-sensitive adhesive Although there is no problem in particular in the characteristic of a sheet, since it is difficult to mass-produce an adhesive, it is not preferable. The main component of the acrylic adhesive polymer is usually a copolymer of a (meth) acrylic acid alkyl ester monomer and a polar group-containing monomer, for example, a copolymer of 2-ethylhexyl acrylate and acrylic acid, isooctyl acrylate and 2-hydroxyethyl methacrylate. Copolymers, ternary copolymers of 2-ethylhexyl acrylate, acrylic acid and 2-hydroxyethyl methacrylate, and the like are used, but are not particularly limited thereto.

In the present invention, the thermally expandable fine particles contain a core material in a polymer of an outer material. When the temperature is increased, the inner material is gasified, and the microcapsule itself swells like a balloon. Examples of the outer substance include inorganic and organic substances, and typical examples thereof include glass, silica, silas, carbon, phenol, vinyl chloride, vinylidene chloride, vinylidene chloride acrylonitrile copolymer, alumina, and zirconia. Examples of the sealed core material include hydrocarbons such as isobutane and propane, or blowing agents such as soda bicarbonate, azobisisobutyronitrile and ammonium carbonate may be used. The expansion initiation temperature can be controlled by changing the combination of the outer and core materials. The particle diameter of these thermally expandable fine particles is preferably in the range of 1 µm to 100 µm, and particularly preferably in the range of 5 µm to 50 µm. In addition, the expansion start temperature is preferably in the range of 50 ° C to 175 ° C, and particularly preferably in the range of 70 ° C to 120 ° C.

The said adhesive composition may add tackifiers, such as rosin resin, terpene resin, and petroleum resin normally used for acrylic resin.

Moreover, you may add the compounding agents normally used, such as a thickener, a thixotropic agent, and a filler, to the said adhesive composition. Examples of the thickener include acrylic rubber and epichlorohydrin rubber. Examples of the thixotropic agent include ultra finely divided silica (Aerozir 300 manufactured by Nippon Aerogels Co., Ltd.) and the like. As the filler, inorganic particles such as calcium carbonate, titanium dioxide, silicon dioxide, α-alumina, hydrated alumina, organic particles such as nylon beads, acrylic beads, silicone beads, organic hollow particles such as vinylidene chloride balloon, polyester, nylon And organic or inorganic short fibers such as rayon and glass. These are added in order to improve mechanical properties, such as stress relaxation property of an adhesive sheet, and are used in the range which does not impair performance.

The pressure-sensitive adhesive composition is liquid and coated on a sheet substrate by a roll coater, a die coater, or the like, and is heated and dried to form a pressure-sensitive adhesive composition layer having a thickness of 5 μm to 100 μm, but preferably 5 μm to 50 μm, It is more preferable to set it as the thickness of 50 micrometers-50 micrometers. In this case, when the thickness of the said adhesive composition layer is smaller than 5 micrometers, it is not recognized that sufficient adhesive force is initially obtained, and if the thickness of the said adhesive composition layer is larger than 100 micrometers, there will be no problem in particular in nature, but preparation of an adhesive sheet In the process, it is not preferable.

In the present invention, a crosslinking agent, an isocyanate compound crosslinking agent, an epoxy compound crosslinking agent, an aluminate compound crosslinking agent or the like which is generally used as a crosslinking agent of an acrylic pressure sensitive adhesive is used. For example, the polyisocyanate crosslinking agent (brand name: L-45 etc.), the epoxy compound type crosslinking agent (brand name: E-AX etc.), the aluminate compound type crosslinking agent (brand name: M-5A etc.) marketed by Soken Chemical Co., Ltd. Although these etc. can be used, it is not limited to these in particular.

In the present invention, the low polar resin layer is composed mainly of olefin resins such as polyethylene, polypropylene, and isoprene resins, and surfactants. It is preferable to set it as 0.01 micrometer-50 micrometers, and, as for the thickness of this low polar resin layer, it is more preferable to set it as 0.1 micrometer-5 micrometers. In this case, when the thickness of the low polar resin layer is smaller than 0.01 μm, the initial adhesiveness is expressed. However, when the thickness of the low polar resin layer is larger than 50 μm, it is not integrated with the highly polar adherend and does not exhibit a function of naturally peeling off after heating. Although the function which peels naturally after expression is expressed, since the initial stage adhesiveness is not expressed, it is not preferable. In order to improve adhesiveness, you may put tackifiers, such as tackfire, in the low polar resin layer as it is 30% or less of the whole.

As resin which forms the said low polar resin layer, the fluorine resin etc. which are lower in polarity than an olefin resin are considered. However, other than the olefin resin, the sliding property at the time of peeling of a resin-adhesive system was bad, and the result of peeling test etc. concluded that magnetic peeling property was inferior at the time of peeling request. Therefore, as the low polar resin of the present invention, the olefin resin, which is not the lowest in polarity, has a certain degree of polarity and the sliding property of the resin itself, and is a material having a self-peelability by heating upon peeling demand. I found the best one. Moreover, the olefin resin as a low polar resin of this invention contains surfactant, the sliding property of the said surfactant is also taken into consideration, and it is a structure with high sliding property and high self-peelability.

It is preferable to make the said low polar resin layer into 97.5 degrees or more by contact angle, It is more preferable to set it as 100 degrees or more, It is more preferable to set it as 105 degrees or more.

The heat-peelable pressure-sensitive adhesive sheet of the present invention has the following characteristics to satisfy the functions of both self-peelability and adhesion.

Since the polarity values are very close to the adherend surface, for example, the green sheet surface and the first layer surface, both are softened and the adhesiveness is increased to act in the bonding direction by heating. However, in this invention, since there exists a 2nd layer, adhesive surface layer and a to-be-adhered body surface do not have high adhesiveness at the time of heating, but act in the direction which peels. And there exists a 2nd layer and takes the structure which satisfy | fills the function of both adhesiveness and peelable property. After sticking to a to-be-adhered body, when a heat test is performed, a part of component of a 2nd layer is transferred to a to-be-adhered body side. By transferring, the integration of an adhesive composition layer and a to-be-adhered body is prevented and peeling is possible.

In the present invention, when adhesiveness is required at normal temperature, the resin of the first layer is brought into contact with the adherend from between the resin of the second layer to develop adhesiveness. In the first step at the time of heating, the thermally expandable fine particles expand and the second layer of resin rises upward. In the second step at the time of heating, the thermally expandable fine particles are also swollen and moved so as to slide on both sides of the thermally expandable fine particles in the second layer. As the resin of the second layer moves, the adhesion between the resin of the second layer and the adherend can be reduced.

In the present invention, the thermally expandable fine particles can contain the average particle diameter smaller than 18 μm, thereby reducing the thickness of the pressure-sensitive adhesive composition layer. When cutting the adherend, if the pressure-sensitive adhesive composition layer is thick, the cutting accuracy is lowered and the yield is lowered. By making the average particle diameter of thermally expansible microparticles | fine-particles small, cutting thickness can be improved thinly and the cutting precision can be improved (when the adhesive composition layer is thick, the vibration by cutting will become large and cutting precision will fall).

In the present invention, two layers of resins having different polarities are satisfied to satisfy the opposite functions of adhesion to the adherend in the beginning and self-peelability after heating. You may coat | cover whole resin of 1st layer with resin of 2nd layer. However, when the entire first layer of resin is coated with the second layer of resin, the self-peelability is increased, but the gap between the adherend and the adherend is filled, resulting in a decrease in the adhesive force. If too much is left with the adherend, adhesiveness is expressed on the contrary, but self-peelability is lowered. It is preferable that the resin of the 2nd layer coat | covers the resin of 1st layer with the area ratio of 0.5%-99%, It is more preferable to coat with the area ratio of 10%-50%, The area of 10%-30% It is a more preferable state to coat | cover at the rate and it will satisfy | fill the functions of both adhesive force and self-peelability.

When the average particle diameter of thermally expansible microparticles | fine-particles is set to about 10 micrometers in this invention, many adhesive polymers exist between the thermally expansible microparticles | fine-particles of a 1st layer. Upon heating, when the thermally expandable fine particles expand, the portion is in close contact with the adherend to prevent magnetic peeling. However, the presence of the second layer of low polar resin layer prevents adhesion between the adhesive polymer between the thermally expandable fine particles and the adherend and facilitates self-peeling.

That is, in this invention, a gap exists between an adhesive sheet and a to-be-adhered body in an initial state by interposing a 2nd low polar resin layer on the surface of a 1st resin layer. When the gap exists, when the thermally expandable fine particles of the first layer are expanded, the gap portion becomes a starting point, so that peeling is promoted and natural peeling becomes easy. Since there is no 2nd layer and there is no gap only by the 1st layer, there is no part which becomes a starting part, and thermally expansible microparticles | fine-particles need to be greatly expanded in order to peel. For this purpose, the initial thermally expandable fine particles require a relatively large particle size. However, when the thermally expandable fine particles are made larger, the cutting accuracy is lowered, and thus the size of the chip inductor or the like that can be cut is limited.

However, in the past, thermally expandable fine particles used a type having an average particle diameter of 20 µm to 40 µm. By using the said type of 20 micrometers-40 micrometers of average particle diameters, the thickness after heating will be 200 micrometers-400 micrometers, and the force which peels a to-be-adhered body becomes large, and becomes easy to peel magnetically. Thus, the thermally expansible microparticles | fine-particles need a thickness of 50 micrometers or more by using the type whose average particle diameter is 20 micrometers-40 micrometers. When the thickness of an adhesive composition layer is thick, when cutting, the cutting precision falls and a yield falls.

In this invention, the thickness of an adhesive composition layer can be reduced by using about 10 micrometers of average particle diameters as mentioned above about the thermally expansible microparticle of a 1st layer, and the said cutting precision can be improved.

In addition, in the present invention, the particle size of the thermally expandable fine particles is small, and the thermally expandable fine particles after heating have only a particle size of about 50 µm to 100 µm, and the force to detach the adherend is small, so that the self-peelability is weak. Therefore, the self-peelability is improved by coating a resin having a low polarity with the adherend on the second layer. That is, in this invention, it is made to have the initial adhesiveness and the self-peelability together with both low-expansion resin and the thermally expandable microparticles | fine-particles with a small particle size of 1st layer, and a to-be-adhered body of 2nd layer.

In this case, when the particle size of the low polar resin is too large with respect to the particle diameter of the second layer, the adhesiveness of the first layer is not expressed and the initial adhesiveness is lost. On the contrary, when the particle size is too small, the function of the second layer is deteriorated and the self-peeling is reduced. Since the property is inferior, the low polar resin of the second layer preferably has an average particle diameter of 0.01 µm to 10 µm, more preferably 0.1 µm to 5.0 µm, and even more preferably 0.2 µm to 3.0 µm.

In addition, in the present invention, if the amount of the thermally expandable fine particles in the first layer is too small, the force to detach the adherend is weak. Therefore, it is not self-peeled, and if too much, it is integrated with the pressure sensitive adhesive and cannot perform the function as a peelable pressure sensitive adhesive sheet. . Therefore, the blending ratio in the resin of the first layer of the thermally expandable fine particles is preferably 2.5 wt% to 50 wt%, more preferably 10 wt% to 40 wt%, and more preferably 10 wt% to 30 wt%. More preferred.

Next, the relationship between the thickness of the heat-peelable pressure-sensitive adhesive sheet of the present invention and the cutting precision of a highly polar adherend such as a ceramic green sheet will be described in detail.

In the case where the green sheet is cut into chips, the precision at the time of cutting becomes very important in order to make the chip itself very small at 1.0 mm or less.

However, when the thickness of the pressure-sensitive adhesive composition layer is thick, a strong force is applied during cutting, and the pressure-sensitive adhesive itself vibrates. If the next cutting is performed before the vibration is collected, the cutting width is not set as set, and cutting accuracy is lowered. If the thickness of the pressure-sensitive adhesive is thinner here, the vibration becomes small and the cutting accuracy does not increase.

Therefore, in the present invention, as described above, the particle size of the thermally expandable fine particles of the first layer of the pressure-sensitive adhesive composition layer is made small, and the second layer is a low-polar resin layer having a polarity that is different from the adherend, and the initial adhesion in both structures. The heat-peelable pressure-sensitive adhesive sheet has a high self-peelability and high cutting accuracy.

In the present invention, when the heat-peel test is performed in the absence of the low-polar resin layer, the adhesive composition layer itself, the polarity is high, if the polarity of the adherend is high, the pressure-sensitive adhesive composition layer and the adherend are integrated before the expansion of thermally expandable fine particles, until peeling It is not early. Therefore, when a low polar resin layer exists, it will prevent that an adhesive composition layer and a high polarity adherend are integrated, and makes it peelable. And with respect to the initial stage adhesive force in the state in which the low polar resin layer exists, the thickness of the said low polar resin layer is made thin, the softness of the 1st layer is expressed, and sufficient adhesive force is expressed. The low polar resin layer is a layer having both a barrier function and a layer having an adhesion function, and has both functions. However, since the low polar resin layer has a low adhesive function, the low polar resin layer is the adhesive polymer of the first layer of the resin layer. I cover it.

In the present invention, the low-polar resin layer of the second layer does not cover the entire first-layer resin layer as described above, but the low-polar resin layer is interspersed, and the first-layer resin layer is invisible. In the initial state (state without heat), the adhesive force is expressed in a state where the adhesive polymer exudes from the resin layer of the first layer. Moreover, since the low polar resin layer itself has adhesiveness, the adhesive force is also expressed by the said low polar resin layer. When it heats, a low polar resin layer becomes a layer provided with the barrier function in order not to integrate with a high polarity adherend. Thereafter, the thermally expandable fine particles contained in the first resin layer can be easily peeled from the adherend by expanding and decreasing the contact area with the adherend.

That is, in this invention, as shown in FIG. 2, the low polar resin layer of 2nd layer is coat | covered in the form of a spot on the surface of the resin layer of 1st layer in a self-organization structure. It does not cover all the resin layers of a 1st layer, nor does it expose all. In some parts, the first layer of the resin layer appears on the surface, and in some parts, the second layer of the low polar resin layer is coated. When the low-polar resin layer of the second layer was covered with a micrograph (1000 times magnification), as shown in FIG. 3, the line was formed with a width of about 210 μm × about 275 μm and width of 5.56 μm as shown in FIG. 3. Therefore, it is preferable to make a total of 1900 grids, and to have 10-1800 pieces of the blank part (the part where the first layer is exposed), more preferably 30 to 1500 pieces, more preferably 50 to 1250 pieces. More preferred. Moreover, it is preferable that the low polar resin layer of a 2nd layer is 500 or less grids in size per one.

In the present invention, the low-polar resin layer of the second layer contains a surfactant in order to increase the sliding property, and when the heat-expandable fine particles of the first layer are expanded upon the peeling request at the time of heating, the low-polar resin layer is prevented from being in close contact. In addition, due to the sliding property of the surfactant, two functions of expansion and sliding can be generated between the interfaces with the adherend, thereby allowing magnetic peeling. The blending ratio of the surfactant in the low polar resin layer is preferably 10% by weight to 75% by weight, more preferably 10% by weight to 50% by weight, still more preferably 10% by weight to 40% by weight. .

In the present invention, the low polar water support material in the second layer is in the form of particles of an olefinic resin and is in the form of a colloidal dispersion. After apply | coating, it can coat | cover in the state which particle size was disperse | distributed to the 1st layer resin layer surface. Surfactant is used in order to improve the compatibility with the resin layer of a 1st layer, and the sliding property of a to-be-adhered body. Although olefin resin is low polarity, since it has sliding property of resin itself, it is self-peelable. Moreover, surfactant is mix | blended and the sliding property is improved.

Next, the expression state of the adhesiveness and peelability of the 2nd low polar resin layer and to-be-adhered body in the heat-peelable adhesive sheet of this invention are demonstrated in detail.

In the initial state (at room temperature before heating), as shown in FIG. 4A, the resin of the first layer (2a) is in close contact with the adherend W and expresses the adhesiveness (the low polar resin of the second layer (2b) is adhesive To adjust the strengths and weaknesses of

Immediately after heating, as shown in FIG. 4B, the thermally expandable fine particles p in the resin of the first layer 2a begin to expand. Since thermally expansible microparticles | fine-particles p expand, the force attracted by both the upper direction and the downward direction generate | occur | produces at the interface of the to-be-adhered body W and resin of 1st layer 2a accordingly. The low polar resin of the 2nd layer (2b) is in the state which is easy to pull up and down. The resin and the adherend W of the first layer 2a are softened by heat, are in close contact with each other, and try to act in the direction of adhesion (because both are similar components). However, since there exists a low polar resin of 2nd layer (2b) of the opposite property, it plays a role which hinders the adhesiveness of the to-be-adhered body W and resin of 1st layer (2a).

After the completion of the heating, the force for pushing up the adherend W of the thermally expandable fine particles p in the resin of the first layer 2a is small, but since there is a low polar resin of the second layer 2b of opposite properties, As shown in the figure, it is possible to easily peel off magnetically. That is, since the thermally expandable fine particles p in the resin of the first layer 2a have a small particle size, there is no force enough to push up the adherend W after expansion, but the low polar resin of the second layer 2b Therefore, it can be self-peeled with the help of the low polar resin.

(Example)

Hereinafter, the heat-peelable pressure-sensitive adhesive sheet of the present invention will be specifically described by way of examples.

[Examples 1 to 4, Comparative Example 1 and Comparative Example 2]

As shown in Table 1, a polyethylene terephthalate (PET) is used as the sheet substrate, and the resin layer of the first layer is formed of a resin containing a tacky polymer, thermally expandable fine particles, and a crosslinking agent, and the low polarity of the second layer is made of amorphous polypropylene. The heat-peelable pressure-sensitive adhesive sheet of the present invention having a resin layer was prepared. As shown in Table 2, the heat-peelable pressure-sensitive adhesive sheet as a comparative example was assumed to have no second layer low-polar resin layer of the heat-peelable pressure-sensitive adhesive sheet of the present invention.

Heat peeling was performed using the heat-peelable pressure-sensitive adhesive sheets of Examples 1 to 4, Comparative Examples 1 and 2, and the measurement of chip holding ratio, self-peelability, cutting accuracy, etc. of these heat-peelable pressure-sensitive adhesive sheets was performed. Carried out. Test conditions and test methods are as follows, and test results are shown in Table 3.

Exam conditions

Heating temperature × time 150 ℃ × 30 seconds

(Example 4 and Comparative Example 2 is 120 ℃ 30 seconds)

Chip size 1 mm x 1 mm

Test Methods

Ten chips of 1 mm x 1 mm are bonded to the adhesive face and the drop of the chip at room temperature is confirmed. Thereafter, a heating test of 150 ° C. × 30 seconds is carried out to check whether all the chips can be peeled off.

Chip Retention Rate: Check the number of chips that do not fall at room temperature. 10/10 if chips do not fall

Self-peelability: A heating test of 150 ° C × 30 seconds is carried out to check the number of chips falling. 10/10 when all chips fall

EXAMPLE 1
Sheet base material PET 100 μm (made by Unichika)
Resin layer of the first layer
Adhesive polymer: acrylic ester copolymer (manufactured by Daidosei) 20 parts
Thermally expandable fine particles: EXPANCEL051 DU40 (Nipponpyraito)
Average particle size 10.5 ㎛ 3.0 parts
Crosslinking agent: Colonate L-45 (Nippon Polyurethane) 1.0 part
Low polar resin layer amorphous PP particle diameter 1.0 micrometer of 2nd layer (Notep High School)

EXAMPLE 2
Sheet base material PET 100 μm (made by Unichika)
Resin layer of the first layer
Adhesive polymer: acrylic ester copolymer (manufactured by Daidosei) 20 parts
Thermally expandable fine particles: EXPANCEL051 DU40 (Nipponpyraito)
Average particle size 10.5 ㎛ 3.0 parts
Crosslinking agent: Colonate L-45 (Nippon Polyurethane) 1.0 part
Low-polar resin layer amorphous PP particle size 0.6 μm of second layer (Notef High School)

EXAMPLE 3
Sheet base material PET 100 μm (made by Unichika)
Resin layer of the first layer
Adhesive polymer: acrylic ester copolymer (manufactured by Daidosei) 20 parts
Thermally expandable fine particles: Microspia F-78K (Matsumoto Yugo High School)
Average particle size 30 ㎛ 3.0 parts
Crosslinking agent: Colonate L-45 (Nippon Polyurethane) 1.0 part
Low polar resin layer amorphous PP particle diameter 1.0 micrometer of 2nd layer (Notep High School)

EXAMPLE 4
Sheet base material PET 100 μm (made by Unichika)
Resin layer of the first layer
Adhesive polymer: acrylic ester copolymer (manufactured by Daidosei) 20 parts
Thermally expandable fine particles: Microspia F-78K (Matsumoto Yugo High School)
Average particle size 30 ㎛ 3.0 parts
Crosslinking agent: Colonate L-45 (Nippon Polyurethane) 1.0 part
Low polar resin layer amorphous PP particle diameter 1.0 micrometer of 2nd layer (Notep High School)

[Comparative Example 1]
Sheet base material PET 100 μm (made by Unichika)
Resin layer of the first layer
Adhesive polymer: acrylic ester copolymer (manufactured by Daidosei) 20 parts
Thermally expandable fine particles: EXPANCEL051 DU40 (Nipponpyraito)
Average particle size 10.5 ㎛ 3.0 parts
Crosslinking agent: Colonate L-45 (Nippon Polyurethane) 1.0 part
There is no low polar resin layer of the second layer

[Comparative Example 2]
Sheet base material PET 100 μm (made by Unichika)
Resin layer of the first layer
Adhesive polymer: acrylic ester copolymer (manufactured by Daidosei) 20 parts
Thermally expandable fine particles: Microspia F-78K (Matsumoto Yugo High School)
Average particle size 30 ㎛ 3.0 parts
Crosslinking agent: Colonate L-45 (Nippon Polyurethane) 1.0 part
There is no low polar resin layer of the second layer

Chip retention Self-peelability Cutting precision Adhesive composition layer thickness Example 1 10/10 10/10 Good 30 μm Example 2 10/10 10/10 Good 30 μm Example 3 10/10 10/10 usually 50 μm Example 4 10/10 10/10 usually 50 μm Comparative Example 1 10/10 0/10 Bad 30 μm Comparative Example 2 10/10 0/10 Bad 50 μm

As shown in Table 3, in Examples 1 to 4, the self-peelability was good and the cutting accuracy was good or normal, but in Comparative Examples 1 and 2, the self-peelability was not good and the cutting precision was also poor.

1: Sheet base material 2: Adhesive composition layer
2a: 1st layer 2b: 2nd layer

Claims (9)

On one side or both sides of a sheet base material, an adhesive composition layer is formed, The said adhesive composition layer is formed from the 1st layer from the said sheet base material side as a layer which consists mainly of adhesive polymer, thermally expansible microparticles, and a crosslinking agent, and the 2nd layer is low polar water. Heat-peelable pressure-sensitive adhesive sheet formed of a ground layer. The method of claim 1,
The adhesive composition layer is a heat-peelable pressure-sensitive adhesive sheet in which the low-polar resin layer of the second layer is interspersed on the surface of the first resin layer. The method of claim 1,
The said adhesive composition layer heat-peelable adhesive sheet which coat | covered the said low polar resin layer of said 2nd layer by the spot shape on the surface of the said 1st layer. The method according to any one of claims 1 to 3,
The pressure-sensitive adhesive composition layer has a thickness of 5 ㎛ to 100 ㎛, heat-peelable pressure-sensitive adhesive sheet. The method according to any one of claims 1 to 3,
The thermally expandable fine particles are heat-peelable pressure-sensitive adhesive sheet having an average particle diameter of less than 18 μm. The method according to any one of claims 1 to 3,
The low polar resin layer has a contact angle of 97.5 ° or more, heat-peelable pressure-sensitive adhesive sheet. The method according to any one of claims 1 to 3,
The low polar resin layer has a thickness of 0.01 μm to 50 μm, the heat-peelable pressure-sensitive adhesive sheet. The method according to any one of claims 1 to 3,
The said low polar resin layer is a heat-peelable adhesive sheet which has an olefin resin and surfactant as a main component. The method of claim 8,
The said low polar resin layer is a heat-peelable adhesive sheet whose said olefin resin is a particle | grain state, and the average particle diameter of the particle | grains is 0.01 micrometer-10 micrometers.

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