KR101675051B1 - Adhesive tape for protecting surface of cover glass for direct bonding and method for direct bonding of cover glass using the same - Google Patents

Abstract

The present invention relates to a polyethylene terephthalate film; An acrylic pressure sensitive adhesive layer laminated on the lower side of the polyethylene terephthalate film; And a release film formed on the lower side of the acryl pressure-sensitive adhesive layer, wherein the upper part of the polyethylene terephthalate film is subjected to a surface charge treatment, and a direct bonding method of a cover glass using the same .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a surface protective adhesive tape for a direct bonding cover glass, and a direct bonding method for a cover glass using the same. BACKGROUND ART < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface protective adhesive tape for a direct bonding cover glass and a direct bonding method for a cover glass using the same. More particularly, the present invention relates to a surface protective adhesive tape for a direct bonding cover glass which comprises an acrylic pressure sensitive adhesive layer laminated on a lower surface of a polyethylene terephthalate film A surface protecting adhesive tape, and a direct bonding method of a cover glass using the same.

In recent years, electronic products such as smart phones and integrated computers have been pursuing product development centered on the increase in size and size of the products, and the performance is greatly increased. Therefore, it is necessary to protect the surface of the cover glass by increasing the addition of the surface function (AS: anti-smudge, AR: anti-reflection, AG: anti-glare) of the cover glass. Accordingly, a direct bonding cover glass requires an adhesive tape that can be applied to alignment, UV curing, and shipment inspection on the bonding (bonding) process.

Previously used cover glass process and adhesive adhesive film at the time of shipment were PE (Polyethylene) self-adhesive protective film produced by dissolving ethylene-vinyl acetate (EVA) resin by heat and PE (polyethylene) An adhesive protective film in which an acrylic pressure-sensitive adhesive is coated to 3 to 10 占 퐉 has been widely used. However, this type of adhesive protective film had to be removed from the glass during the process and re-attached to ship. For direct bonding, it was necessary to add a process to clean the cover glass again before the injection (conventional process flow: glass processing → PE self-adhesive attachment → shipment → PE removal → cleaning → bonding → PE self-adhesive attachment → shipment) .

In addition, the migration of vinyl acetate components of ethylene-vinyl acetate (EVA) has a potential risk of rising contamination issues.

Korean Patent Publication No. 10-2013-0067084

In order to solve the above-mentioned problems, the conventional adhesive protective film has to be removed from the cover glass during the process and then shipped again. However, unlike the conventional method requiring separate cleaning process, A protective tape for direct bonding of a cover glass for direct bonding including a polyethylene terephthalate film and an acrylic pressure-sensitive adhesive layer which can be directly fed into a direct bonding without process, simplifies the process, easily removes the adhesive tape, And a method of directly joining a cover glass using the same.

In order to solve the above-mentioned problems, the present invention provides a polyethylene terephthalate film;

An acrylic pressure sensitive adhesive layer laminated on the lower side of the polyethylene terephthalate film; And

And a release film formed below the acrylic pressure sensitive adhesive layer,

And the upper surface of the polyethylene terephthalate film is subjected to a surface charge treatment, thereby providing a surface protective adhesive tape of a cover glass for direct bonding.

In one embodiment of the present invention, the polyethylene terephthalate film may have a thickness of 25 to 100 mu m.

In an embodiment of the present invention, the acrylic pressure sensitive adhesive layer may include an acrylic copolymer.

In one embodiment of the present invention, the acrylic copolymer may comprise from 60 to 95% by weight of acrylic acid, from 0.5 to 20% by weight of an unsaturated monomer containing hydroxyl and carboxyl groups and from 0.1 to 5% by weight of a reactive emulsifier have.

In one embodiment of the present invention, the reactive emulsifier may be at least one of acryloyl and methacrylol.

In one embodiment of the present invention, the acrylic copolymer may further comprise 0.1 to 5% by weight of a crosslinking agent based on the total amount of the acrylic copolymer.

In one embodiment of the present invention, the crosslinking agent may be at least one selected from the group consisting of an isocyanate compound, an epoxy compound and a metal compound.

In one embodiment of the present invention, the acrylic copolymer may further comprise 0.1 to 5% by weight of an antistatic agent based on the total amount of the acrylic copolymer.

In one embodiment of the present invention, the antistatic agent may be at least one selected from the group consisting of a lithium anion, an ammonium-based cation, a polysiloxane-based cation, and a glycol ether anion.

In one embodiment of the present invention, the thickness of the acrylic pressure-sensitive adhesive layer after drying may be 10 to 30 탆.

In one embodiment of the present invention, the surface charge treatment is selected from the group consisting of polyacetylene, polypyrrole, polythiophene, polyaniline, poly (3,4-ethylenedioxythiophene) and poly (thienylenevinylene) Or may be one using at least one conductive polymer.

In one embodiment of the present invention, the surface charging performance by the surface charging treatment may be 10 ^{5 to 10} Ω / sq.

Further, the present invention provides a direct bonding method of a cover glass in which the surface-protecting adhesive tape is used for direct bonding.

According to an embodiment of the present invention, the direct bonding method may include attaching the surface protecting adhesive tape to a cover glass and directly introducing the surface protecting adhesive tape directly into the bonding without a separate washing step.

 According to the surface protective adhesive tape of the cover glass for direct bonding of the present invention, when a surface protective adhesive tape comprising a polyethylene terephthalate film and an acrylic pressure sensitive adhesive layer is laminated and shipped in a cover glass, And the surface of the cover glass can be protected without changing the adhesive protective film from the post-bonding to the shipment until after the bonding. Removal of the adhesive tape is easy and there is no residue of the adhesive, so that convenience and efficiency of the direct bonding process can be improved.

1 is a schematic view showing a surface protecting adhesive tape of a cover glass for direct bonding according to an embodiment of the present invention.
2 is a photograph showing a process of laminating a surface protecting adhesive tape of a cover glass for direct bonding according to an embodiment of the present invention to a cover glass.
3 is a view showing a state in which a surface protecting adhesive tape of a cover glass for direct bonding according to an embodiment of the present invention is laminated on both sides of a cover glass.

Hereinafter, preferred embodiments of the present invention will be described in detail in order to facilitate the present invention by those skilled in the art.

The present invention relates to a polyethylene terephthalate film; An acrylic pressure sensitive adhesive layer laminated on the lower side of the polyethylene terephthalate film; And a release film formed on the lower side of the acrylic pressure sensitive adhesive layer, wherein the upper surface of the polyethylene terephthalate film is subjected to a surface electrification process.

In the present invention, direct bonding is a process of directly joining a cover glass and an LCD module. A UV adhesive is injected between the cover glass and the LCD module to UV cure (ultraviolet cure) to form an integral type.

In the present invention, it is preferable that the polyethylene terephthalate film has a high tensile strength, a small elongation, and a small heat shrinkage, and it is preferable that the film has optical properties and does not use recycled paper.

For example, the polyethylene terephthalate film preferably has a strength of 15 kgf / 15 mm or more in the MD direction and 20 kgf / 15 mm or more in the TD direction, and the elongation is preferably less than 120% in the MD and TD directions. Particularly in the case of heat shrinkage It is preferably 0.3% or less at 60 to 80 ° C.

In the present invention, the polyethylene terephthalate film may have a thickness of 25 to 100 탆. Specifically, the polyethylene terephthalate film may have a thickness of 25 탆, 38 탆, 50 탆, 75 탆 and 100 탆. When the thickness is less than 25 mu m, folding may occur during the lamination operation, and when the thickness is more than 100 mu m, it may be difficult to cut the film.

In the present invention, the acrylic pressure sensitive adhesive layer may include an acrylic copolymer.

The acrylic copolymer may be an acrylic copolymer which is a main component of the pressure-sensitive adhesive layer composition and preferably has a peel off-static property. The above-mentioned acrylic copolymer is preferable because it has suitable adhesive force, re-releasability and antistatic function and does not leave any stain after re-peeling.

The molecular weight of the acrylic copolymer is preferably 40 to 900,000 Mw. If the molecular weight is less than 400,000 Mw, the pressure-sensitive adhesive softens and there is a risk of metastasis. If the molecular weight exceeds 900,000 Mw, there is a problem of high adhesion and adhesion on the coating due to a rapid reaction.

The acrylic copolymer may contain 60 to 95 wt% of acrylic acid, 0.5 to 20 wt% of an unsaturated monomer containing a hydroxyl group and a carboxyl group, and 0.1 to 5 wt% of a reactive emulsifier based on the total weight of the acrylic copolymer.

The acrylic acid may be at least one selected from the group consisting of, for example, methylacrylate, ethylacrylate, butyl acrylate and octyl acrylate. When the content of acrylic acid is less than 60% by weight, the adhesive strength is lowered. When the content is more than 95% by weight, the adhesive strength is increased.

The unsaturated monomer containing a hydroxyl group and a carboxyl group is preferably selected from the group consisting of hydroxyl ethyl acrylate, hydroxyl ethyl methacrylate, hydroxyl propyl acrylate and carboxyl ethyl acrylate carboxy ethyl acrylate). If the content of the monomer is less than 0.5% by weight, the pressure-sensitive adhesive tends to soften and there is a risk of the transition. If the content of the monomer exceeds 20% by weight, the pressure-sensitive adhesive becomes too hard,

The reactive emulsifier may be one or more of acryloyl and methacrylol. The reactive emulsifier is an anionic emulsifier containing an allyl group and participates in the radical polymerization and strengthens the binding force with the antistatic agent.

If the content of the reactive emulsifier is less than 0.1% by weight, the binding force with the antistatic agent may be weakened, and if the amount exceeds 5% by weight, the emulsifier may be transferred.

The acrylic copolymer may further contain 0.1 to 5% by weight of a crosslinking agent based on 100% by weight of the acrylic copolymer. When the amount of the cross-linking agent is less than 0.1% by weight, crosslinking becomes insufficient, adhesive strength increases, and desirable re-release properties may not be obtained.

The crosslinking agent is not particularly limited, but may be at least one selected from the group consisting of an isocyanate compound, an epoxy compound and a metal compound. The isocyanate compound may be an aromatic diisocyanate such as diisocyanate or xylene diisocyanate, an adduct of hexamethylene diisocyanate or a compound having a hydroxyl group.

The acrylic copolymer may further contain an antistatic agent in an amount of 0.1 to 5% by weight, preferably 0.2 to 2% by weight, based on the total amount of the acrylic copolymer. If the content of the antistatic agent is less than 0.1% by weight, the effect is largely ineffective. If the content is more than 5% by weight, contamination of the adherend may occur.

The antistatic agent lowers the electrical resistance value of the acrylic copolymer and exhibits an antistatic effect. In general, in order to exhibit the antistatic effect, the surface resistance value is preferably 10 ¹¹ Ω / sq or less.

The antistatic agent is not particularly limited, but may be at least one selected from the group consisting of lithium anion, ammonium cation, polysiloxane cation and glycol ether anion.

In addition, the acrylic pressure sensitive adhesive layer of the present invention may further contain an accelerator, a retarder, a plasticizer, a UV stabilizer, an antioxidant, etc., depending on the purpose.

The promoter may be, for example, a tin compound.

As the retarder, for example, 2,4-pentanedione may be used.

In the present invention, the acrylic pressure-sensitive adhesive layer may have a thickness of 10 to 30 탆 after drying. If the thickness is less than 10 mu m, the adhesive force is too low. If the thickness is more than 30 mu m, the adhesive force is too high.

The method of applying the acrylic pressure-sensitive adhesive layer in the present invention is not particularly limited as long as it is a coating method generally used in the art. For example, a die coater, a dip coater, a gravure roll coater, a comma coater, or the like can be used.

The releasing film is not particularly limited as far as it exhibits releasability to an acrylic pressure-sensitive adhesive, and for example, a silicon-based releasing agent and a wax-based releasing agent can be used.

In the present invention, the top of the polyethylene terephthalate film is surface-treated. The surface charging performance by the surface charging treatment is preferably maintained at 10 ^{5 to 10} Ω / sq, and it is desirable to secure the solvent resistance and the abrasion resistance.

In the present invention, the surface charge treatment may be performed by, for example, gravure roll coating, microgravure roll coating or kiss-gravure roll coating, but the present invention is not limited thereto.

In the present invention, the surface charging treatment uses at least one conductive polymer selected from the group consisting of polyacetylene, polypyrrole, polythiophene, polyaniline, poly (3,4-ethylenedioxythiophene) and poly (thienylenevinylene) To perform a gravure roll, a microgravure roll, or a kiss gravure roll coater

The physical properties of the surface protective adhesive tape according to the present invention are as follows: the adhesive strength is 3 to 6 gf / inch, the adhesive surface resistance is 10 ^{10 to 11} Ω / sq, the peeling electrification is 0.5 kv or less, the haze is 4 ± 1% ± 1%.

In addition, the present invention provides a direct bonding method for a cover glass, comprising the step of attaching the surface protecting adhesive tape to a cover glass and directly applying direct bonding without a separate cleaning process.

According to the present invention, the surface-protecting adhesive tape can be laminated on the cover glass in accordance with the direct bonding manufacturing process and can be shipped directly to the bonding, and the surface of the cover glass can be protected without changing the protective adhesive tape until shipping after bonding . Since there is no need to change the protective adhesive tape, a separate cleaning process is also not required. That is, in the case of using the adhesive tape according to the present invention, it is possible to achieve the simplification of the direct bonding process of the cover glass since only the glass processing, the surface protective adhesive tape attaching, the shipping, the bonding, and the shipping are required.

2 and 3, a surface protective adhesive tape according to the present invention is attached on the AS (anti-smudge layer) and BM (black matrix) regions of the cover glass. The surface protecting adhesive tape according to the present invention may be attached to one or both surfaces of a cover glass.

The present invention will be described in more detail through the following examples. However, the examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

[Example 1]

A surface charging process 20 is applied to the upper surface of the polyethylene terephthalate film 10 as a kiss gravure roll and the acrylic pressure sensitive adhesive 30 is laminated on the lower surface of the polyethylene terephthalate film 10 subjected to the surface charging process 20 , And a polyethylene terephthalate release film (40) subjected to release treatment on the lower side of the acrylic pressure sensitive adhesive layer (30) was laminated to produce a surface protective pressure sensitive adhesive tape. The composition of the acrylic pressure-sensitive adhesive used is shown in Table 1 below. The surface protective adhesive tape thus produced is shown in Fig. In Table 1, the polyacrylate adhesive 1 has a weight average molecular weight of 60,000 and an acrylic acid content of 70% by weight. The polyacrylate pressure-sensitive adhesive 2 had a weight average molecular weight of 1,000,000 and an acrylic acid content of 96% by weight.

Components of the acrylic pressure-sensitive adhesive layer (weight%) acryl
(Polyacrylate adhesive 1) acryl
(Polyacrylate adhesive 2) accelerant
(Tin compound) Retarder
(2,4-pentanedione) Cross-linking agent
(Isocyanate) Antistatic agent
(Glycol ether anion) Example 1 100 - 0.2 2 2 One Example 2 100 - 0.3 2.5 3 0.5 Comparative Example 1 - 100 0.2 2 2 One Comparative Example 2 - 100 0.3 2.5 3 0.5 Comparative Example 3 - 100 0.3 3 2.5 One

[Experimental Example 1]

The properties of the adhesive strength, surface resistance, peeling electrification, and optical properties were measured for Examples 1 and 2 and Comparative Examples 1 to 3. Each measurement method is as follows, and the results are shown in Table 2 and Table 3, respectively.

≪ Basic property measurement method >

* Adhesion test (CKP-5000)

① Adhesive tape was cut into 25 mm width and 250 mm length in machine direction.

(2) The peel strength was measured while peeling at a peeling speed of 300 m / min using a peel test method using an adhesive force measuring device (CKP-5000).

③ Separation test The specimens were laminated to a cleaned or dried glass or SUS plate using an automatic padding machine (2 kg load) and stored at 25 ± 2 ° C for 30 minutes.

④ Adhesive force was measured by peel test at a peeling speed of 300 m / min using a peel test method using an adhesive force measuring device (CKP-5000).

* Surface resistance test (MCP-HT450)

① Adhesive tape Cut 10mm × 10mm in the left, middle, and right direction in the transverse direction.

(2) The release film was removed with a surface resistance meter (MCP-HT450) and the resistance of the adhesive surface was measured (the applied voltage was 100 V).

* Peeling-off test (FMX-003)

① Adhesive tape Cut 50mm × 250mm in the left, middle, and right direction in the transverse direction.

(2) The sample was allowed to stand for 30 minutes after being attached to the glass with a load of 2 kg and peeled off at a peeling speed of 300 m / min by a 180 ° peel test method to measure the chargeability of the adhesive surface.

* Optical properties (NDH-2000)

① Adhesive tape Cut 50mm × 50mm in the left, middle, and right direction in the transverse direction.

② Samples were fixed to the measuring equipment in the same direction for transmission / haze measurement.

③ The results were recorded.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 adhesiveness
(gf / inch) AS
(Anti-Smudge layer) 3.13 3.17 3.62 5.83 4.17 3.10 3.01 3.16 6.31 3.95 BM
(Black Matrix) 4.01 4.44 9.50 16.36 14.46 3.75 4.60 10.63 16.69 13.69 Glass 3.41 3.40 3.19 11.97 8.64 3.55 3.19 3.02 10.98 9.07

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Adhesive sheet resistance
(Ω / m ² ) 6.29 X10 ¹⁰ 9.89 X ^{10 10} 1.35 × ^{10 10} 7.80 × ^{10 10} 2.35 × ^{10 11} 6.21 X10 ¹⁰ 9.00 × ^{10 10} 1.39 × ^{10 10} 8.06 × ^{10 10} 2.58 X ^{10 11} Peeling war
kV AS 0.13 0.42 0.38 -0.03 0.20 0.15 0.39 0.41 -0.04 0.40 BM 0.02 0.00 0.09 -0.06 0.00 0.04 0.02 0.08 -0.05 0.01 Haze (%) 3.46 3.65 3.65 3.63 3.19 3.55 3.50 3.62 3.78 3.42 Transmittance (%) 89.70 89.72 89.82 90.64 89.93 89.70 89.79 89.89 90.36 89.95

As a result of the test, the pressure-sensitive adhesive composition according to the present invention had an appropriate adhesive force, and no signs of contamination of the pressure-sensitive adhesive were observed even after peeling off the adhesive. Also, the surface resistivity of the pressure-sensitive adhesive was 10 < ¹¹ > or less, indicating that the peeling electrification effect was secured.

10 base film
20 surface charge treatment
30 Acrylic pressure-sensitive adhesive layer
40 release film
50 Cover Glass
51 AS (Anti-Smudge layer)
52 BM (Black Matrix)
100 surface protection adhesive tape

Claims (14)

Polyethylene teraphthalate film;
An acrylic pressure sensitive adhesive layer containing an acrylic copolymer and laminated on the lower side of the polyethylene terephthalate film; And
And a release film formed below the acrylic pressure sensitive adhesive layer,
The upper portion of the polyethylene terephthalate film is surface-treated,
The molecular weight of the acrylic copolymer is 400,000 to 900,000 Mw,
Wherein the acrylic copolymer comprises 60 to 95% by weight of acrylic acid, 0.5 to 20% by weight of an unsaturated monomer containing a hydroxyl group and a carboxyl group, and 0.1 to 5% by weight of a reactive emulsifier,
A surface protective adhesive tape of a cover glass for direct bonding having an adhesive strength of 3 to 6 gf / inch, which is attached to a cover glass including a black matrix (BM) region. The method according to claim 1,
Wherein the polyethylene terephthalate film has a thickness of 25 to 100 占 퐉. delete delete The method according to claim 1,
Wherein the reactive emulsifier is at least one of acryloyl and methacrylotl. The method according to claim 1,
Wherein the acrylic copolymer further comprises 0.1 to 5% by weight of a crosslinking agent based on the total amount of the acrylic copolymer. The method according to claim 6,
Wherein the crosslinking agent is at least one selected from the group consisting of an isocyanate compound, an epoxy compound and a metal compound. The method according to claim 1,
Wherein the acrylic copolymer further comprises an antistatic agent in an amount of 0.1 to 5% by weight based on the total amount of the acrylic copolymer. 9. The method of claim 8,
Wherein the antistatic agent is at least one selected from the group consisting of a lithium anion, an ammonium-based cation, a polysiloxane-based cation, and a glycol ether anion. The method according to claim 1,
Wherein the acrylic pressure-sensitive adhesive layer has a thickness of 10 to 30 占 퐉 after drying. The method according to claim 1,
Wherein the surface charging treatment uses at least one conductive polymer selected from the group consisting of polyacetylene, polypyrrole, polythiophene, polyaniline, poly (3,4-ethylenedioxythiophene) and poly (thienylenevinylene) Surface protective adhesive tape. The method according to claim 1,
Wherein the surface charging performance by the surface charging treatment is 10 ^{5 to 10} Ω / sq. A direct bonding method for a cover glass, wherein the surface-protecting adhesive tape according to any one of claims 1 to 5 and 12 to 12 is used for direct bonding. 14. The method of claim 13,
Wherein the direct bonding method comprises a step of attaching the surface protecting adhesive tape to a cover glass and directly introducing the surface protecting adhesive tape directly without any washing step.

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