KR102368252B1 - Low dielectric adhesive tape with high heat resistance - Google Patents

Abstract

The present invention relates to a high heat resistance low dielectric adhesive tape, wherein the adhesive tape is formed by laminating an adhesive layer on one or both sides of a substrate, wherein the adhesive layer is 2-ethylhexyl acrylate (2-EHA) 20 to 30 weight parts, 30 to 40 parts by weight of 2-hydroxyethyl methacrylate (2-HEMA), 10 to 15 parts by weight of isobutyl methacrylate (IBMA), 15 to 25 parts by weight of cyclohexyl methacrylate (CHMA); and an acrylic pressure-sensitive adhesive resin composition comprising 1 to 3 parts by weight of acrylic acid.

Description

High heat resistance, low dielectric adhesive tape. {LOW DIELECTRIC ADHESIVE TAPE WITH HIGH HEAT RESISTANCE}

The present invention relates to a high heat resistance low dielectric adhesive tape, and more particularly, to an adhesive tape excellent in adhesive strength and heat resistance while maintaining a low dielectric constant even in a high frequency region of 800 MHz or higher.

The low-k adhesive tape is used for IT devices such as displays and mobile phones, and is generally formed by laminating an adhesive composition on both sides of a substrate. Recently, as 5G communication is activated, parts materials with low dielectric constant are being developed to secure communication reliability, and adhesive tapes with low dielectric constant are also being developed.

In the case of using an existing adhesive tape, there is a problem in that communication quality is deteriorated due to frequency loss in the 5G environment. In addition, in order to be applied to recent IT devices that generate a lot of heat, the heat resistance of the adhesive tape needs to be high.

In order to secure the dielectric properties of the low-k adhesive tape, in the prior art, the type and molecular weight of the resin are optimized (Korean Patent Publication No. 10-2102971), or a method of adding a dielectric property control resin to the pressure-sensitive adhesive composition (Korean Patent Publication No. 10) -1572010)) are being developed, but there is a problem in that it is difficult to meet the requirements for maintaining the adhesive performance required for the adhesive tape and especially the adhesive performance at a high temperature even when a low dielectric constant is achieved.

The present invention has been devised in view of the problems of the prior art as described above, and an object of the present invention is to provide an adhesive tape excellent in adhesive strength and heat resistance while maintaining a low dielectric constant even in a high frequency region.

The adhesive tape of the present invention for solving the above problems is an adhesive tape in which an adhesive layer is laminated on one or both sides of a substrate, wherein the adhesive layer is 2-ethylhexyl acrylate (2-EHA) 20 to 30 weight parts, 30 to 40 parts by weight of 2-hydroxyethyl methacrylate (2-HEMA), 10 to 15 parts by weight of isobutyl methacrylate (IBMA), 34 parts by weight of cyclohexyl methacrylate (CHMA), and acrylic acid It is characterized in that it comprises an acrylic pressure-sensitive adhesive resin composition consisting of 1 to 3 parts by weight.

In this case, the pressure-sensitive adhesive layer may additionally contain 15 to 25 parts by weight of a terpene phenol-based tackifying resin. In addition, the pressure-sensitive adhesive layer may additionally contain 40 to 80 parts by weight of hollow silica as an inorganic filler.

The adhesive tape according to the present invention exhibits excellent adhesive strength and heat resistance while maintaining a low dielectric constant even in a high frequency region, thereby maintaining a low dielectric constant even in a high frequency region, and exhibiting adhesive strength and heat resistance required for an adhesive tape.

1 is a cross-sectional view showing the laminated structure of the adhesive tape according to the present invention, and is a view showing an adhesive tape (a) having an adhesive layer formed on one side and an adhesive tape (b) having an adhesive layer formed on both sides of the adhesive tape.

Hereinafter, the present invention will be described in more detail. The terms or words used in the present specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

The adhesive tape according to the present invention is made by laminating an adhesive layer on one or both sides of a substrate as shown in FIG. 1 , and a release layer may be formed on the outside of the adhesive layer. The tape on which the base material and the pressure-sensitive adhesive layer are laminated has a thickness of about 100 μm, and the thickness may vary depending on the use.

The pressure-sensitive adhesive layer is configured to include an acrylic pressure-sensitive adhesive resin composition, the acrylic pressure-sensitive adhesive resin composition is configured to exhibit heat resistance as well as adhesive strength, 2-ethylhexyl acrylate (2-EHA) 20 to 30 parts by weight, 2- 30 to 40 parts by weight of hydroxyethyl methacrylate (2-HEMA), 10 to 15 parts by weight of isobutyl methacrylate (IBMA), 34 parts by weight of cyclohexyl methacrylate (CHMA), and 1 to 3 parts by weight of acrylic acid may include wealth.

In addition, the pressure-sensitive adhesive layer may further contain 15 to 25 parts by weight of a terpene phenol-based tackifying resin. When the amount of the tackifying resin is less than 15 parts by weight, the adhesive force becomes insufficient, and when it exceeds 25 parts by weight, the surface of the pressure-sensitive adhesive layer is hardened and sufficient support cannot be obtained. should be included

In addition, the pressure-sensitive adhesive layer may additionally contain 40 to 80 parts by weight of hollow silica as an inorganic filler. By containing the inorganic filler, it is possible to obtain low dielectric properties of the pressure-sensitive adhesive composition.

It was found that when the content of the inorganic filler is too small, the effect of lowering the dielectric constant of the pressure-sensitive adhesive layer is not exhibited. In addition, it was found that if the content of the inorganic filler is too large, the adhesive strength of the low-k tape is lowered and there is a risk of losing the function as a tape.

In the present invention, hollow silica is used as the inorganic filler, and by using such a material, excellent heat resistance and low dielectric constant characteristics can be obtained.

The hollow silica preferably has an average particle diameter (D50) of 5 to 20 μm. If the average particle diameter of the hollow silica is less than 5㎛, there is a risk that the contact resistance increases and the unit price increases. appeared to be of concern.

In addition, it is preferable to modify the surface of the hollow silica to improve dispersibility when included in the pressure-sensitive adhesive layer. The surface-modified hollow silica may be prepared by mixing a hydrophobic surface modifier with ethanol and dispersing the hollow silica in the mixed solution. In addition, as the surface modifier having the hydrophobicity, it is preferable to use stearic acid, which can control the hydrophobicity of the silica powder. In this case, the hollow silica and stearic acid are preferably mixed in a weight ratio of 10:1 to 3:1. If the content of stearic acid is too small, the surface modification of the hollow silica is insufficient and there is no difference from using unmodified hollow silica. Rather, it was shown to decrease.

The present invention will be described in more detail with reference to the following examples.

[Production of high heat-resistant acrylic pressure-sensitive adhesive resin composition]

28 parts by weight of 2-ethylhexyl acrylate (2-EHA), 34 parts by weight of 2-hydroxyethyl methacrylate (2-HEMA), 12 parts by weight of isobutyl methacrylate (IBMA), 34 parts by weight of cyclohexyl Methacrylate (CHMA), 1 part by weight of acrylic acid, and 0.1 parts by weight of the reaction initiator azobis isobutyronitrile (AIBN) were put into a 4-neck 1-liter glass reactor and polymerized to prepare an acrylic pressure-sensitive adhesive resin composition.

[Hollow Silica Surface Modification]

1 part by weight of stearic acid and 5 parts by weight of hollow silica were added to 94 parts by weight of ethanol and sufficiently dispersed with a high pressure disperser to prepare a silica dispersion. The prepared silica dispersion was dried in a cylindrical electric furnace at 250° C. to prepare a surface-modified hollow silica coated with stearic acid.

[Example 1]

The prepared acrylic pressure-sensitive adhesive resin composition was diluted with ethyl acetate, an organic solvent, so that the solid content was 40%, and 40 parts by weight of the surface-modified hollow silica with respect to 100 parts by weight of the diluted acrylic pressure-sensitive adhesive resin composition, an epoxy type general curing agent (Tetrad- X) 0.01 parts by weight, 25 parts by weight of a terpene phenol-based tackifier, and 1.5 parts by weight of a fluidity regulator (BYK-410) were added to prepare a low-k acrylic pressure-sensitive adhesive composition.

The heat-reactive acrylic pressure-sensitive adhesive composition was applied to a release-treated film to a thickness of 25 μm, and dried by heating at 110° C. for 3 minutes to prepare a first low-k adhesive layer. A second low-k acrylic adhesive layer was prepared in the same manner and laminated on both sides of a 50 μm-thick polyethylene terephthalate (PET) substrate to prepare a low-k tape with a total thickness of 100 μm.

[Example 2]

A low-k adhesive tape was prepared in the same manner as in Example 1, except that the content of the terpene phenol-based tackifier was changed to 15 parts by weight.

[Example 3]

A low-k adhesive tape was prepared in the same manner as in Example 1, except that the content of the surface-modified hollow silica was changed to 50 parts by weight.

[Example 4]

A low-k adhesive tape was prepared in the same manner as in Example 1, except that the content of the surface-modified hollow silica was changed to 70 parts by weight.

[Comparative Example 1]

A low-k adhesive tape was prepared in the same manner as in Example 1, except that hollow silica was not mixed with the acrylic pressure-sensitive adhesive resin composition.

[Comparative Example 2]

A low-k adhesive tape was prepared in the same manner as in Example 1, except that the acrylic pressure-sensitive adhesive resin composition was mixed with the unmodified hollow silica.

[Comparative Example 3]

A tape having a total thickness of 100 μm was prepared without mixing the surface-modified hollow silica with the acrylic pressure-sensitive adhesive resin composition using a commercially available high heat-resistant acrylic pressure-sensitive adhesive resin.

[Comparative Example 4]

A low-k adhesive tape was prepared in the same manner as in Example 1 except that a commercially available high heat-resistant acrylic adhesive resin was used for the acrylic adhesive resin composition.

For the adhesive tapes according to Examples and Comparative Examples, adhesive force, holding force, and heat resistance were evaluated as follows. The evaluation results are shown in Table 1.

[Adhesive force test]

Cut the low-k adhesive tape to 25mm in width and 200mm in length, use a 2kg roller to reciprocate once at a speed of 300mm/min, and press it onto a SUS 304 steel plate. Peel strength at 180° (degree) at a speed of 300mm/min. was measured.

[Retention Test]

After attaching the low-k adhesive tape to the SUS 304 steel plate at 25×25 mm, it was compressed by reciprocating twice at a speed of 25 mm/sec using a 2 kg roller, and left for 1 hour under a load of 1 kg in a chamber at 80 ° C. The distance or fall time was measured.

[Heat resistance test]

After attaching the low-k adhesive tape to the SUS 304 steel plate at 25×25 mm, press it back and forth twice at a speed of 25 mm/sec using a 2 kg roller, and increase the temperature by 10° C. After reaching 150°C, it was left for 30 minutes to measure the temperature that fell while the temperature was raised to 150°C. If it did not fall to 150°C, the pushed distance was measured.

[Permittivity Test]

The low-k adhesive tape was measured using a dielectric constant measuring device, DAK-TL (SPEAG). The test frequency was set to 800 MHz.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 3 Adhesion (g/25mm) 1,685 1,321 1,427 1,213 2,149 1,438 1,835 1542 Holding force (mm) <1 <1 2 5 <1 2 <1 45 min Drop Heat resistance (℃) 150 150 140 120 150 140 150 110 permittivity
(at 800MHz) 2.78 2.86 2.36 2.24 3.77 3.25 3.85 3.24

Referring to the results in Table 1, it was confirmed that, in Comparative Example 1 except for the hollow silica, the adhesive strength and heat resistance were excellent, but the dielectric constant was high. In addition, in the case of Comparative Example 2 using a general hollow silica having an unmodified surface, it was confirmed that the dispersibility of the silica was lowered, the dielectric constant was increased, and the heat resistance was decreased. In addition, in the case of Comparative Example 4 in which hollow silica was applied to a commercially available high heat-resistant strong adhesive adhesive, it was confirmed that the adhesive strength and heat resistance were inferior due to the hollow silica particles. In addition, Comparative Example 3 was found to be unsuitable as an adhesive tape because the adhesive strength was too low.

On the other hand, in the case of the adhesive tape to which the pressure-sensitive adhesive composition according to Examples 1 to 4 is applied, it was confirmed that the adhesive strength was good while exhibiting the characteristics of high heat resistance and low dielectric constant. These results suggest that when the pressure-sensitive adhesive composition according to the present invention is applied, a low-k adhesive tape exhibiting high heat resistance can be manufactured.

Therefore, the adhesive tape according to the present invention can implement high adhesive force, holding power, and a thin thickness of the adhesive layer, so that it can be applied to various uses that require functions such as light blocking, shock absorption, conduction, heat dissipation, and EMI shielding.

The present invention has been described with reference to a preferred embodiment as described above, but it is not limited to the above embodiment, and various modifications and changes can be made by those skilled in the art to which the present invention pertains without departing from the spirit of the present invention. Changes are possible. Such modifications and variations are intended to fall within the scope of the present invention and the appended claims.

Claims (3)

In the adhesive tape formed by laminating an adhesive layer on one or both sides of a substrate,
The pressure-sensitive adhesive layer is 20 to 30 parts by weight of 2-ethylhexyl acrylate (2-EHA), 30 to 40 parts by weight of 2-hydroxyethyl methacrylate (2-HEMA), 10 to 10 parts by weight of isobutyl methacrylate (IBMA) 15 parts by weight, 34 parts by weight of cyclohexyl methacrylate (CHMA), and 1 to 3 parts by weight of acrylic acid A high heat resistance low dielectric adhesive tape comprising an acrylic adhesive resin composition.
The method according to claim 1,
The pressure-sensitive adhesive layer is a high heat resistance low dielectric adhesive tape, characterized in that it additionally contains 15 to 25 parts by weight of a terpene phenol-based tackifying resin.
The method according to claim 1,
The pressure-sensitive adhesive layer is a high heat resistance low dielectric adhesive tape, characterized in that it additionally contains 40 to 80 parts by weight of hollow silica as an inorganic filler.

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