KR20210016751A - Multilayer adhesive tape - Google Patents

Abstract

The present invention relates to a multilayer adhesive tape having excellent adhesion at high temperature. In the present invention, a first adhesive layer, a second adhesive layer and a substrate are sequentially laminated, wherein the first adhesive layer and the second adhesive layer satisfy a storage modulus ratio (storage modulus of the second adhesive layer/storage modulus of the first adhesive layer) at -20°C greater than 0 and less than or equal to 1.

Description

Multilayer adhesive tape{MULTILAYER ADHESIVE TAPE}

The present invention relates to a multilayer adhesive tape, and more particularly, to a multilayer adhesive tape having excellent flexibility and no cracking, less change in viscoelasticity in various temperature ranges, and excellent adhesion at high temperatures.

In general, a display may include a polarizing plate made of a plate-like material, a retardation plate, and additional functional layers. These are attached to the adherend inside the device through the pressure-sensitive adhesive, and can be manufactured in various forms such as bent or folded.

On the other hand, future displays, especially mobile displays, are expected to develop into thinner, lighter, less energy-consuming, paper-thin and flexible flexible displays according to the deepening, generalization, and popularization of information.

In the case of an adhesive film used in a conventional flat panel display, there is little deformation due to an external force, but in the case of an adhesive film applied to a flexible display, stress occurs due to external bending or bending when used. In this case, it is difficult to be deformed into a curved shape due to the viscoelasticity of the adhesive itself, and problems such as being lifted or peeled off due to stress transfer to the display or deformation of external stress occur, and thus a problem that cannot be applied to the flexible display occurs.

Therefore, it is urgent to develop a pressure-sensitive adhesive that can be used as a member of a flexible or flexible display because it is flexible due to little change in viscoelasticity in a variety of temperature ranges, and less cracking occurs under conditions requiring flexibility during display processing/operation.

Korean Patent Publication No. 10-1908290

The present invention has been devised to solve the above problems and meet the conventional requirements, and an object of the present invention is to have excellent flexibility under conditions that require flexibility during application to a curved substrate or display processing or operation, causing cracks There is no change in viscoelasticity in various temperature ranges, and it is intended to provide a multilayer adhesive tape with excellent adhesion at high temperatures.

The above and other objects and advantages of the present invention will become more apparent from the following description of preferred embodiments.

For the above object, the first adhesive layer, the second adhesive layer, and the substrate are sequentially positioned, and the first adhesive layer and the second adhesive layer have a storage modulus ratio at -20° C. satisfying the following Equation 1,

(Equation 1)

0 <K ≤ 1

And K is achieved by a multilayer adhesive tape, characterized in that the storage modulus of the second adhesive layer/the storage modulus of the first adhesive layer.

Preferably, the first adhesive layer and the second adhesive layer are characterized in that the storage modulus at -20°C is 0.1KPa to 1,000KPa.

Preferably, the first adhesive layer and the second adhesive layer are characterized in that the storage modulus at 25° C. is 0.1 KPa to 20 KPa.

Preferably, the first adhesive layer and the second adhesive layer are characterized in that the storage modulus at 160° C. is 0.1 KPa to 10 KPa.

Preferably, the first adhesive layer and the second adhesive layer are an addition curable silicone pressure sensitive adhesive composition comprising at least one MQ resin, at least one organosiloxane polymer having a vinyl functional group, at least one organohydrogen silicon compound, and a hydrosilylation catalyst. It is characterized in that it is located coated.

Preferably, the molar ratio of the M unit and the Q unit of the MQ resin is 0.6:1 to 4:1.

Preferably, it is characterized in that the molecular weight of the organosiloxane polymer is 25,000 to 200,000 g/mol.

Preferably, the organooxygen silicon compound is characterized in that it is at least one cross-linked organohydrogensiloxane compound having an average of at least two Si-H bonds per molecule.

Preferably, the thickness after drying of the first adhesive layer and the second adhesive layer is characterized in that 1 ~ 30㎛.

Preferably, the adhesive force of the first adhesive layer and the second adhesive layer is characterized in that 500 to 2,000 gf/inch.

According to the present invention, it has excellent flexibility under conditions that require flexibility during application to a curved substrate or display processing or operation, so there is no crack, less change in viscoelasticity in various temperature ranges, and excellent adhesion at high temperatures. .

However, the effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a schematic cross-sectional view of a multilayer adhesive tape according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention and drawings. These examples are only illustratively presented to illustrate the present invention in more detail, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not limited by these examples. .

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control. Also, although methods and materials similar or equivalent to those described herein may be used in the practice or testing of the present invention, suitable methods and materials are described herein.

As used herein, "comprise", "comprising", "include", "including", "containing", "~ The terms characterized by", "has", "having" or any other variation thereof are intended to cover inclusions that are not exclusive. For example, a process, method, article, or apparatus comprising a list of elements is not necessarily limited to those elements, and is not explicitly listed or may include other elements inherent to such process, method, article, or apparatus. May be. Further, unless expressly stated to the contrary, "or" refers to an inclusive'or' and not an exclusive'or'.

First, a multilayer adhesive tape according to an aspect of the present invention will be described in detail with reference to FIG. 1, which is a schematic cross-sectional view of a multilayer adhesive tape according to a preferred embodiment of the present invention.

Referring to FIG. 1, in the multilayer adhesive tape 100 according to an embodiment of the present invention, a first adhesive layer 110, a second adhesive layer 120, and a substrate 130 are sequentially positioned.

In the case of adhesive tape (or adhesive film), since it was conventionally composed of a single layer of adhesive layer, only one stress behavior was possible, so there was a limit in relieving the stress against the stress on each surface when the adhesive tape was bent. , As a result, the stress that occurs when the adhesive tape is bent is not resolved, resulting in a problem that the upper panel and structural layer are destroyed or the shape is deformed.In particular, the adhesive tape applied to the flexible display is externally bent or bent when used. As a result, the stress is transmitted to the display or the multilayer adhesive tape according to the present invention can solve various problems caused by such stress. That is, according to the present invention, a multilayer with excellent flexibility and no cracks by adjusting the storage modulus ratio of the first adhesive layer and the second adhesive layer under conditions requiring flexibility during application to a curved substrate or display processing or operation. Adhesive tape can be provided.

In one embodiment, the substrate 130 serves as a support layer of the adhesive tape and may include a material having adhesion to the adhesive layer. For example, a plastic material such as a polyester series such as polyethylene terephthalate (PET), a polycarbonate series, a polyolefin series, and a polyimide series may be included.

In one embodiment, the first adhesive layer and the second adhesive layer may have a storage modulus of 0.1 KPa to 1,000 KPa at -20°C. If the storage modulus of -20℃ exceeds 1,000KPa, the adhesive layer becomes hard and cracks may occur in the adhesive layer itself or the adhesion to the adherend may be deteriorated. In the case of less than 0.1KPa, it becomes soft and is required by the adhesive tape. It cannot have more than 500gf/inch adhesive strength.

In addition, it is preferable that the storage modulus ratio (K) of the first adhesive layer and the second adhesive layer at -20° C. satisfies Equation 1 below.

(Equation 1)

0 <K ≤ 1

Here, K is the storage modulus of the second adhesive layer/the storage modulus of the first adhesive layer.

By keeping the storage modulus ratio (K) of the first adhesive layer and the second adhesive layer of Equation 1 below 1, when the adhesive tape is bent to the substrate surface, the adhesive layer (the second adhesive layer) has a low storage modulus. The stress of the structure laminated with the base material is reduced, thereby preventing the occurrence of cracks in the adhesive layer.

In one embodiment, the first adhesive layer and the second adhesive layer may have a storage modulus of 0.1 KPa to 20 KPa at 25°C.

In one embodiment, the first adhesive layer and the second adhesive layer may have a storage modulus at 160° C. of 0.1 KPa to 10 KPa.

When the storage modulus at 25°C and the storage modulus at 160°C are in the above ranges, there is little change in the physical properties of the adhesive layer, so it has stability even at high temperature processes.

In one embodiment, the first adhesive layer 110 or the second adhesive layer 120 includes a silicone resin, and is formed from a silicone composition. The first adhesive layer 110 or the second adhesive layer 120 may include one or more MQ resins [A]; At least one organosiloxane polymer [B] having a vinyl functional group; At least one organohydrogen silicon compound [C]; And it may be positioned coated with an addition curable silicone pressure-sensitive adhesive (PSA) composition comprising a hydrosilylation catalyst [D].

MQ resin [A] is a silicone resin and refers to a resin bonded according to the MQ ratio, which is the ratio of M-resin and Q-resin, as shown in Formula 1 below, and the material that binds Si in the M-resin is In the case of MQ resins that exist in various ways, but are generally used commercially, Si-CH ₃ is usually attached and is called organopolysiloxane.

[Formula 1]

Here, R ₃ is an alkyl group. However, without departing from the scope of the present invention, instead of the methyl group, other aliphatic groups having up to about 20 carbon atoms may be used. In addition, the MQ resin may contain up to 5% by weight of silanol functional groups, with less than about 1% by weight may alternatively be used.

In the MQ resin of Formula 1, the molar ratio of the M unit and the Q unit is preferably 0.6:1 to 4:1. If the molar ratio between the M unit and the Q unit in Formula 1 is less than 0.6:1, the size and molecular weight of the MQ resin increases, so that the compatibility with the organosiloxane polymer of Formula 2 below decreases, and the viscosity is too high to make coating. When the molar ratio of M unit and Q unit exceeds 4:1, the size and molecular weight of the MQ resin decreases, so it has good compatibility with the organosiloxane polymer of Formula 2 below, and its viscosity is low, making it easy to coat the manufacturing process. This is because the dispersibility is inferior and migration occurs at high temperatures, resulting in poor physical property uniformity.

In addition, the organosiloxane polymer [B] is an organosiloxane polymer terminal blocked with a vinyl functional group, and may be represented by the following formula (2). It may also contain additional vinyl functional groups. In the present invention, the viscosity and the degree of curing after coating may be controlled by different molecular weights of two or more organosiloxane polymers.

[Formula 2]

R ₁ R ₂ ViSiO(R ₃ R ₄ SiO) _n SiR ₅ R ₆ Vi

Here, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ may be the same as or different from each other as an alkyl group or a phenyl group having 1 to 6 carbon atoms, and n may be an integer of 1 or more. The alkyl group of Formula 2 may be exemplified by methyl, ethyl, propyl, butyl, pentyl, hexyl or cyclopentyl and cyclohexyl.

The molecular weight of the organosiloxane polymer of Formula 2 is preferably 25,000 to 200,000 g/mol so that the second adhesive layer 120 has good folding and bending properties. When the molecular weight of the organosiloxane polymer is less than 25,000 g/mol, the degree of curing is greatly increased during curing, resulting in poor flexibility. If the degree of curing is lowered, the stability of the peel force over time decreases. In addition, when the molecular weight of the organosiloxane polymer exceeds 200,000 g/mol, the stability of physical properties increases, but the viscosity increases, resulting in a problem that uniform coating is impossible.

In addition, the organohydrogen silicon compound [C] includes one or more cross-linked organohydrogensiloxane compounds having an average of two or more Si-H bonds per molecule, and is represented by the following formula (3). Organohydrogensiloxane compounds suitable for use are preferably linear, branched, or cyclic molecules and any mixtures or combinations thereof.

[Formula 3]

-(R ₇ HSiO)n-

Here, R ₇ is a C 1 to C 6 alkyl group or a phenyl group. The alkyl group of Formula 3 may be exemplified by methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopentyl, or cyclohexyl.

In addition, the hydrosilylation catalyst [D] may include any catalyst known to a person skilled in the art to be useful in catalyzing the hydrosilylation reaction. The catalyst may be preferably a platinum group metal-containing catalyst. By definition, a platinum group metal refers to ruthenium, rhodium, palladium, osmium, iridium, and platinum metals, as well as any mixtures or complexes thereof. The platinum group metal may include solid or hollow particles, a layer deposited on a carrier such as silica gel or powdered charcoal, or an organometallic compound or complex. Some examples of platinum-containing catalysts include chloroplatinic acid in hexahydrate or anhydrous form, and platinum-containing catalysts obtained by reacting chloroplatinic acid or this platinum chloride with an aliphatic unsaturated organosilicon compound. It is preferable to use a platinum complex of 1,3 diethenyl-1,1,2,2-tetramethyldisiloxane, which has a platinum concentration of about 5,200 ppm among the many catalysts described above, and is diluted with a vinyl end-blocked polymer. Do. As an example of such a catalyst, a Pt 4000 catalyst (Dow Corning Corporation) may be used.

In one embodiment, the thickness of the first adhesive layer or the second adhesive layer after drying may be 1 to 30 μm. If the thickness is less than 1 μm after drying, the adhesive strength of 500 gf/inch or more cannot be formed due to the low thickness, and if it exceeds 30 μm, there is a problem that the cost and time increase when manufacturing the adhesive tape.

In one embodiment, it is preferable that the adhesive strength of the first adhesive layer and the second adhesive layer is 500 to 2,000 gf/inch. At this time, if the adhesive force is less than 500 gf/inch, the adhesive force with the substrate 130 is lowered, and peeling occurs from the adhesive surface of the first adhesive layer 110 or the second adhesive layer 120 before cracking occurs, and 2,000 gf/inch When it exceeds an inch, a hard adhesive is required to achieve such a high adhesive force. In the case of such a hard adhesive, the storage modulus increases and cracks may occur.

Hereinafter, the configuration of the present invention and effects thereof will be described in more detail through examples and comparative examples. However, the present examples are for explaining the present invention more specifically, and the scope of the present invention is not limited to these examples.

[Example]

[Example 1]

Step 1: Preparation of pressure-sensitive adhesive composition

In a 1,000 ml chemical reactor equipped with stirrer, reflux cooler, thermometer and nitrogen injector, solid MQ resin 40g with weight average molecular weight of 2,000~20,000g/mol and OH content of less than 5% [Component A], weight average molecular weight 51 g of the main polymer resin having 50,000 ~ 600,000 g/mol and a vinyl functional group content of less than 0.1% [Component B], 8.5 g of an organohydrogen silicon compound having a Si-H content of 0.5 to 1.5% [Component C] Add 60 g of toluene as a solvent and stir for about 2 hours to sufficiently mix at room temperature. To this mixture, 0.5 g of a platinum complex of 1,3 diethenyl-1,1,2,2-tetramethyldisiloxane diluted with a vinyl endblocked polymer with a platinum content of 5,200 ppm [Component D] I hit 100g.

Step 2: Preparation of multilayer adhesive film

After drying the pressure-sensitive adhesive composition prepared in Step 1 on a PET film (brand name MNT-100, Sewoong) having a thickness of 75 μm (trade name MNT-100, Sewoong), coated to a thickness of 5 μm, drying and curing in an oven at 150° C. for 5 minutes To form a first adhesive layer.

Next, the pressure-sensitive adhesive composition prepared in Step 1 was dried on a PET film having a thickness of 75 μm and coated to a thickness of 15 μm, and dried and cured in an oven at 150° C. for 5 minutes to form a second adhesive layer.

Thereafter, the first adhesive layer and the second adhesive layer were sequentially stacked to prepare a multilayer adhesive film having a first adhesive layer/second adhesive layer/PET structure.

At this time, the storage modulus ratio (K) of -20°C of the first adhesive layer and the second adhesive layer is 0.56.

[Example 2]

A multilayer adhesive film was manufactured in the same manner as in Example 1, except that the thickness after drying of the first adhesive layer of Example 1 was 10 μm and the thickness after drying of the second adhesive layer was 10 μm. At this time, the storage modulus ratio (K) of -20°C of the first adhesive layer and the second adhesive layer is 0.34.

[Example 3]

A multilayer adhesive film was manufactured in the same manner as in Example 1, except that the thickness after drying of the first adhesive layer of Example 1 was 3 μm and the thickness after drying of the second adhesive layer was 17 μm. At this time, the storage modulus ratio (K) of -20°C of the first adhesive layer and the second adhesive layer is 0.89.

[Example 4]

A multilayer adhesive film was manufactured in the same manner as in Example 1, except that the thickness after drying of the first adhesive layer of Example 1 was 10 μm and the thickness after drying of the second adhesive layer was 10 μm. At this time, the storage modulus ratio (K) of -20°C of the first and second adhesive layers is 1.00.

[Comparative Example 1]

After drying the first adhesive layer of Example 1, the thickness was set to 20 μm, and an adhesive film was prepared in the same manner as in Example 1, except that there was no second adhesive layer.

[Comparative Example 2]

After drying the second adhesive layer of Example 1, the thickness was set to 20 μm, and an adhesive film was prepared in the same manner as in Example 1, except that the first adhesive layer was not present.

[Comparative Example 3]

A multilayer adhesive film was prepared in the same manner as in Example 1, except that the storage modulus ratio (K) of -20°C of the first adhesive layer and the second adhesive layer was 1.49.

[Comparative Example 4]

A multilayer adhesive film was prepared in the same manner as in Example 1, except that the storage modulus ratio (K) of -20°C of the first adhesive layer and the second adhesive layer was 2.01.

Physical properties were measured through the following experimental examples using the multilayer adhesive tape according to Examples 1 to 4 and Comparative Examples 1 to 4, and the results are shown in Table 1 below.

[Experimental Example]

1. Storage modulus (kPa) measurement

Viscoelasticity was measured in shear mode (1 Hz) using ARES (TA instruments), which is a dynamic viscoelasticity measuring device (Frequency: 1 rad/sec). After the release film was removed, the adhesive films of Examples and Comparative Examples were laminated to have a thickness of 1 mm, and the laminate was punched out with a puncher having a diameter of 8 mm, and used as a specimen. It was measured at a rate of increase of 10 ℃/min in the temperature range of -50 ℃ to 180 ℃, the storage modulus ratio (K) of -20 ℃ of the first adhesive layer and the second adhesive layer, the first adhesive layer and the second adhesive The storage modulus of the two layers combined at 25° C. and 160° C. are shown in Table 1 below, respectively.

2. Measurement of adhesion (gf/in)

A sample of a PET film/adhesive layer/PET film structure was prepared, and the sample was cut into 1 inch x 15 cm strips. At the time point 60 minutes after attachment, using a texture analyzer (TAXplus/50, SMS), the adhesive strength was measured by a 180° peel test method at a speed of 5 mm/sec (0.3m/min).

3. Flexibility characteristics

A sample of a PET film/first adhesive layer/second adhesive layer/PET film structure was used to perform a flexural test to determine the presence of delamination (disconnected without adhesion), streaks, and bubbles.

In addition, the flexural test was laminated in the above order and folded in the direction of the PET film of the second adhesive layer at 25°C and 90°C for reliability evaluation, and the appearance after 2 weeks was confirmed. At this time, the bending radius was 3mm. The delamination state was observed at or near the bending part, and fine bubbles were judged as bubbles and elliptical bubbles as stripes.

O: No air bubbles and streaks

X: Delamination occurs

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 First adhesive layer thickness (㎛) 5 10 3 10 20 - 10 10 Second adhesive layer thickness (㎛) 15 10 17 10 - 20 10 10 Adhesion (gf/in) 685 671 531 551 1,500 131 30 20 Storage modulus at 25℃ (kPa) 10.9 12.1 11.2 10.5 20.4 5.5 4.2 3.5 160℃ storage modulus (kPa) 7.45 7.88 8.55 7.55 15.0 4.3 5.0 3.0 Storage modulus ratio (K) of -20℃ 0.56 0.34 0.89 1.00 - - 1.49 2.01 Flexibility evaluation O O O O X X X X Reliability evaluation O O O O X X X X

As can be seen from Table 1, in the case of Examples 1 to 4 according to the present invention, the storage modulus ratio of -20°C is maintained at 1 or less, so that excellent results can be confirmed in the evaluation of flexural resistance and reliability.

On the other hand, in the case of Comparative Example 1, it was found that a good result was not obtained in the flexural property due to the property that was hardened due to the high storage modulus, and in the case of Comparative Example 2, it was found that the result was not good in the evaluation of flexibility and reliability due to low adhesion. I can.

In addition, in the case of Comparative Examples 3 and 4, the storage modulus of the first adhesive layer and the second adhesive layer was low, and the adhesive strength was low, so peeling occurred during the evaluation of flexibility and reliability, indicating poor results in the evaluation of flexibility and reliability. .

In the present specification, only a few examples of various embodiments performed by the present inventors are described, but the technical idea of the present invention is not limited or limited thereto, and it is obvious that it may be modified and variously implemented by those skilled in the art.

100: multilayer adhesive tape
110: first adhesive layer
120: second adhesive layer
130: substrate

Claims (10)

The first adhesive layer, the second adhesive layer and the substrate are sequentially positioned,
The first adhesive layer and the second adhesive layer have a storage elastic modulus ratio at -20°C satisfying the following Equation 1,
(Equation 1)
0 <K ≤ 1
And K is the storage modulus of the second adhesive layer/the storage modulus of the first adhesive layer, a multilayer adhesive tape. The method of claim 1,
The first adhesive layer and the second adhesive layer has a storage modulus of 0.1KPa to 1,000KPa at -20°C, a multilayer adhesive tape. The method of claim 1,
The first adhesive layer and the second adhesive layer has a storage modulus of 0.1KPa to 20KPa at 25°C, a multilayer adhesive tape. The method of claim 1,
The first adhesive layer and the second adhesive layer has a storage modulus of 0.1KPa to 10KPa at 160°C, a multilayer adhesive tape. The method of claim 1,
The first adhesive layer and the second adhesive layer are coated with an addition curable silicone pressure sensitive adhesive composition comprising at least one MQ resin, at least one organosiloxane polymer having a vinyl functional group, at least one organohydrogen silicon compound, and a hydrosilylation catalyst. Positioned, multi-layer adhesive tape. The method of claim 1,
The molar ratio of the M unit and the Q unit of the MQ resin is 0.6:1 to 4:1, a multilayer adhesive tape. The method of claim 1,
The organic siloxane polymer has a molecular weight of 25,000 to 200,000 g/mol, a multilayer adhesive tape. The method of claim 1,
The organic oxygen silicon compound is at least one cross-linked organic hydrogen siloxane compound having an average of 2 or more Si-H bonds per molecule, a multilayer adhesive tape. The method of claim 1,
After drying the first adhesive layer and the second adhesive layer thickness is 1 ~ 30㎛, multi-layer adhesive tape. The method of claim 1,
The adhesive strength of the first adhesive layer and the second adhesive layer is 500 to 2,000 gf/inch, a multilayer adhesive tape.

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