JP2003292911A - Colored adhesive tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a colored adhesive tape having high scratch resistance and leaving no adhesive on an adherend when peeled off the adherend. <P>SOLUTION: The colored adhesive tape is a combination of a film coated with an ink containing a resin component having a specific hydroxyl number with an adhesive containing an isocyanate-based crosslinking agent and/or epoxy-based crosslinking agent and having a specific gel fraction. Specifically, the colored adhesive tape is such one that an ink layer is interposed between a film and an adhesive layer. The gel fraction of the adhesive is 30-80%, and the hydroxyl number of the resin component 1-10. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a colored adhesive tape. More specifically, the present invention relates to a colored adhesive tape having excellent scratch resistance and excellent releasability when it is peeled from an adhered surface such as a metal or plastic that has been once applied.

[0002]

2. Description of the Related Art Colored adhesive tapes (hereinafter referred to as colored adhesive tapes) are used in various industrial fields for the purposes of decoration, display, concealment, light shielding, and the like. Especially in display electronics, black colored adhesive tape
It is used favorably in terms of concealment and shading.

Conventionally, a colored adhesive tape having an ink layer between a film and an adhesive layer has been used as a colored adhesive tape having excellent scratch resistance.

The electronic equipment for display is subjected to aging after the casing of the liquid crystal display element, and then subjected to shipping inspection, and the liquid crystal display element which is defective as a result of the inspection is reworked by removing the tape and reworked.

However, in the conventional tape, the adhesiveness between the ink layer and the pressure-sensitive adhesive is poor, and when peeling, the interface between the ink layer and the pressure-sensitive adhesive is destroyed, and the pressure-sensitive adhesive remains on the adherend. .

[0006]

The object of the present invention is to provide a colored pressure-sensitive adhesive tape which is excellent in scratch resistance and does not leave an adhesive on the adherend when re-peeled from the adherend. To do.

[0007]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors, a film coated with an ink having a resin component having a specific hydroxyl value contains an isocyanate crosslinking agent or an epoxy crosslinking agent, and It was found that the problem of the present invention can be solved by combining the pressure-sensitive adhesives having the gel fraction of, and the present invention has been completed.

In a pressure-sensitive adhesive tape having an ink layer between a pressure-sensitive adhesive layer and a film, the pressure-sensitive adhesive contains at least one of an isocyanate cross-linking agent and an epoxy cross-linking agent, and has a gel fraction of 30 to 80%. Provided is a colored adhesive tape which is an adhesive and has a hydroxyl value of 1 to 10 in the resin component of the ink.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The colored adhesive tape of the present invention will be described below in more detail based on its constituent elements.

(Constitution of Colored Adhesive Film) The constitution of the colored adhesive tape of the present invention is in the form of an adhesive tape having an ink layer between the film and the adhesive layer as shown in FIGS. 1, 2 and 3. FIG. 1 shows the form of a single-sided adhesive tape, and FIGS. 2 and 3 show the form of a double-sided adhesive tape. In the case of the double-sided adhesive tape, the ink layer has only one side as shown in FIG. 2 and the ink layer as shown in FIG. 3 has both sides.

(Scratch resistance) Since the ink layer is present between the film and the adhesive layer as described above, the scratch resistance is excellent.

(Hydroxyl value of ink resin component) When the hydroxyl value of the resin component of the ink layer used in the colored adhesive tape of the present invention is less than 1, sufficient adhesion between the ink and the adhesive cannot be obtained. When the hydroxyl value exceeds 10, it becomes difficult to adjust the crosslink density of the ink. Preferably, the hydroxyl value is 1-5
Is.

(Crosslinking Agent of Ink) The ink used in the colored adhesive tape of the present invention preferably contains an isocyanate crosslinking agent in order to improve the adhesion between the film and the ink layer. Among them, the hexamethylene diisocyanate adduct is preferable because it is easy to achieve both the adhesion between the film-ink layer and the ink layer-adhesive layer.

(Ink affinity parameter γ) The ink affinity parameter γ of the ink layer of the colored adhesive tape of the present invention is preferably 50 or less. More preferably, it is 10 or less. When it exceeds 50, the ink layer becomes too hard, and the pressure-sensitive adhesive hardly penetrates into the ink layer, so that sufficient adhesion between the ink and the pressure-sensitive adhesive cannot be obtained.

The ink affinity parameter γ was measured by rubbing a 1 μm ink coat layer provided on PET with a cotton swab impregnated with toluene and measuring the number of times the ink started to fade. It can be evaluated that the smaller the value of γ, the higher the affinity with the ink.

(Composition of ink resin component) The composition of the ink resin component is not particularly limited, but a vinyl chloride / vinyl acetate copolymer having a hydroxyl group or a carboxyl group, an acrylic resin, polyurethane, or nitrocellulose is preferable. These resins may be used alone or in combination.

A preferred embodiment is a mixture of a vinyl chloride / vinyl acetate copolymer obtained by copolymerizing vinyl alcohol and a urethane resin.

Among them, when used in combination with an isocyanate cross-linking agent, a mixture of vinyl chloride / vinyl acetate copolymer having a hydroxyl value of 2 or more copolymerized with vinyl alcohol and soft polyurethane having an amine value of 0.2 or more. Is more preferable. If the amine value is less than 0.2, the wettability of the ink with the film is reduced.

(Coloring Material) The coloring material of the present invention is not particularly limited, but known and commonly used pigments and dyes can be used. Among them, carbon black for black, titanium oxide, calcium carbonate, barium sulfate for white,
Yellow iron oxide for yellow, red iron oxide for red, ultramarine blue, dark blue for blue, aluminum powder for silver, and mica titanium powder for pearl, due to their weather resistance, heat resistance, and dispersibility in ink resin. preferable.

Among them, carbon black is preferable for light-shielding applications. The addition amount of carbon black is preferably 10 to 70% with respect to the ink dry component. More preferably, it is 40 to 50%. If it is less than 10%, sufficient light-shielding properties cannot be obtained, and if it exceeds 70%, the dispersibility of carbon decreases.

(Thickness of Ink Layer) When used for light shielding, the thickness of the ink layer is preferably 2 to 4 μm. 2μ
If it is less than m, it is difficult to obtain a sufficient light-shielding property. If it exceeds 4 μm, the workability during tape punching will deteriorate.

(Light-shielding property) For light-shielding use, it is preferable that the adhesive tape has a light transmittance of 0.1% or less over a wavelength range of 200 to 1100 nm because it can be evaluated as having a high light-shielding property.

(Ink coating method) As a printing method,
Printing can be carried out by known methods. For example, letterpress printing, flexographic printing, dry offset printing, gravure printing, gravure offset printing, offset printing, screen printing and the like can be adopted. Among them, for light-shielding applications, it is preferable to coat the gravure printing method two to four times so that pinholes are small.

(Film) The film used in the colored adhesive tape of the present invention is not particularly limited,
Known and commonly used films can be used. For example, cellophane, polyethylene, polypropylene, nylon,
Examples thereof include polystyrene, polyimide, vinyl chloride and polyester. Among them, polyester, which is excellent in strength and insulation, is preferable. The film thickness is 6-100 μm
Is preferred. If it is less than 6 μm, the film is likely to be peeled off at the time of peeling, and if it is more than 100 μm, peeling is likely to occur at the time of sticking to the surface. More preferably, 12-50 μm
Is. Further, a pigment may be kneaded into these resins.

(Easy Adhesion Treatment) It is preferable to perform various easy adhesion treatments in order to improve the adhesion between the film and the ink. As the easy-adhesion treatment, corona treatment or plasma treatment is preferable because it does not select the type of ink. As for the treatment level, it is preferable to treat the film surface so that the wettability is 42 dyn / cm or more. More preferably, 48dy
It is at least n / cm, more preferably at least 54 dyn / cm.

(Crosslinking Agent in Adhesive) The adhesive used in the colored adhesive tape of the present invention contains at least one of an isocyanate crosslinking agent and an epoxy crosslinking agent. The isocyanate-based crosslinking agent or the epoxy-based crosslinking agent reacts with a hydroxyl group or a carboxyl group in the pressure-sensitive adhesive to improve the cohesive force of the pressure-sensitive adhesive. Further, it reacts with the hydroxyl group and the carboxyl group of the ink resin component to improve the adhesion between the ink and the adhesive.

Examples of the isocyanate cross-linking agent include tolylene diisocyanate, hexamethylene diisocyanate and adducts thereof. Among them, the tolylene diisocyanate adduct is particularly excellent in the adhesion between the ink and the pressure-sensitive adhesive.

As the epoxy crosslinking agent, epoxy compounds such as diglycidyl aniline and glycerin diglycidyl ether are used. These cross-linking agents may be used alone or in combination of two or more kinds.

(Gel Fraction of Adhesive) The gel fraction of the adhesive of the present invention is 30 to 80%. More preferably, 35-70%
Is. If the gel fraction is less than 30%, the cohesive force of the pressure-sensitive adhesive will be insufficient, and the adhesive will break between the pressure-sensitive adhesive layers during peeling, leaving an adhesive residue. If the gel fraction exceeds 80%, the adhesiveness will decrease.

(Adhesive Composition) The adhesive resin composition of the present invention is not particularly limited, but an acrylic adhesive is preferred because of its excellent weather resistance.

The main component of the acrylic adhesive is
It is obtained by copolymerizing a (meth) alkyl acrylate with a monomer having a hydroxyl group or a carboxyl group, and polymerizing this by a known radical polymerization method such as solution polymerization, emulsion polymerization or bulk polymerization.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and 4-hydroxybutyl acrylate. Examples of the carboxyl group-containing monomer include acrylic acid, itaconic acid, and carboxypropyl acrylate.

(Additive) A known and commonly used additive can be added to the pressure-sensitive adhesive. For example, plasticizers, softeners, fillers, pigments, flame retardants and the like can be added.

[0034]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. The "parts" displayed below are "parts by mass".

(Preparation of ink) 100 parts of Sumi Ink "Panacia CVL-SPR805 Sumi" manufactured by Dainippon Ink and Chemicals, Inc., 4 parts of "CVL Hardener No.10" manufactured by Dainippon Ink and Chemicals, Inc. Made "Die Reducer V No.20" 35
Ink A was prepared by adding some parts. Similarly, inks B to D were prepared according to the formulations shown in Table 1.

[0036]

[Table 1]

(Preparation of Ink Coat Film) Polyester film "Emblet S-25" manufactured by Unitika was corona-treated so that the wetting tension was 50 dyn / cm, and the dry thickness of the ink A was 2 μm on the corona-treated surface. Gravure coated twice so that Further, it was cured at 40 ° C. for 2 days to obtain an ink coat film (a).

Using inks B to D instead of ink A,
Ink coat films (b) to (d) were prepared in the same manner.

(Preparation of Acrylic Copolymer 1) Cooling Tube,
In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, 92.8 parts of n-butyl acrylate, 5 parts of vinyl acetate, 2 parts of acrylic acid,
0.2 parts of β-hydroxy-ethyl acrylate and 0.2 parts of 2,2′-azobisisobutylnitrile as a polymerization initiator were dissolved in 100 parts of ethyl acetate, and after nitrogen substitution, polymerization was carried out at 80 ° C. for 8 hours to obtain a weight average molecular weight. 600,000 acrylic copolymer 1 was obtained.

(Preparation of Acrylic Pressure-Sensitive Adhesive Composition 1) The above acrylic copolymer 1 was manufactured by Arakawa Chemical Co., Ltd.
15 parts of "A100" and 5 parts of "Pencel D135" were added and diluted with toluene to obtain an acrylic pressure-sensitive adhesive composition 1 having a solid content of 45%.

(Preparation of Acrylic Copolymer 2) Cooling Tube,
In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, 92 parts of n-butyl acrylate, 8 parts of acrylic acid, and 0.2 parts of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 100 parts of ethyl acetate. After substitution with nitrogen, polymerization was carried out at 80 ° C. for 8 hours to obtain an acrylic copolymer 2 having a weight average molecular weight of 600,000.

(Preparation of acrylic pressure-sensitive adhesive composition 2) The above acrylic copolymer 1 was diluted with toluene to obtain an acrylic pressure-sensitive adhesive composition 2 having a solid content of 40%.

(Example 1) (Preparation of pressure-sensitive adhesive tape) 1.5 parts of "Coronate L-45" (isocyanate-type crosslinking agent) manufactured by Nippon Polyurethane Industry Co., Ltd. was mixed with acrylic pressure-sensitive adhesive composition 1 and stirred sufficiently. A pressure-sensitive adhesive layer 1 was obtained by coating a release-treated 75 μm-thick polyester film so that the thickness after drying was 25 μm, and drying at 100 ° C. for 2 minutes. This is the ink coat film (a)
Transfer to the ink coated surface of 4kgf / cm with a hot roll at 80 ℃
It was laminated at a pressure of 1 and further cured at 40 ° C. for 2 days to obtain a single-sided adhesive tape.

Example 2 A single-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the ink coat film (b) was used instead of the ink coat film (a).

Example 3 A single-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the ink coat film (c) was used instead of the ink coat film (a).

(Example 4) 2.5 parts of "E05X" (epoxy type cross-linking agent) manufactured by Soken Chemical Industry Co., Ltd. was added to the acrylic pressure-sensitive adhesive composition 2, and the mixture was thoroughly stirred and then demolded to give a polyester having a thickness of 75 μm The pressure-sensitive adhesive layer 2 was coated on the film so that the thickness after drying was 25 μm, and dried at 100 ° C. for 2 minutes.
This was transferred to the ink-coated surface of the ink-coated film (a), laminated with a heat roll at 80 ° C. under a pressure of 4 kgf / cm, and further cured at 40 ° C. for 2 days to obtain a single-sided adhesive tape.

Comparative Example 1 A single-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the ink coat film (d) was used instead of the ink coat film (a).

(Comparative Example 2) 0.5 parts of "Coronate L-45" (isocyanate type cross-linking agent) manufactured by Nippon Polyurethane Industry Co., Ltd. was added to acrylic pressure-sensitive adhesive composition 1, thoroughly stirred, and then subjected to release treatment. It was coated on a 75 μm thick polyester film so that the thickness after drying was 25 μm, and dried at 100 ° C. for 2 minutes to obtain an adhesive layer 3. Transfer this to the ink-coated surface of the ink-coated film (a), and use a hot roll at 80 ° C for 4 kg.
It was laminated at a pressure of f / cm and further cured at 40 ° C. for 2 days to obtain a single-sided adhesive tape.

The single-sided pressure-sensitive adhesive tapes prepared in Examples and Comparative Examples were tested for adhesive strength, removability, and
The constant load peeling property and the light shielding property were evaluated. The evaluation results are shown in Tables 2 and 3
Described in.

(Adhesive strength) A 25 mm wide adhesive tape was attached to a stainless steel plate under a pressure of 23 kg at 50% RH with a 2 kg roller for one reciprocating pressure.
After standing for 1 hour, the film was pulled at 23 ° C. and 50% R at a speed of 300 mm / min to measure the 180 ° peel adhesive strength.

(Removable property) An adhesive tape having a width of 10 mm was attached to a stainless steel plate by a 2 kg roller at 23 ° C. and 50% RH for one reciprocating pressure, left for 1 hour, and then left at 80 ° C. for 12 hours. This 2
After leaving at 3 ℃, 50% RH for 1 hour, pulling speed 1, 5, 10m / min
Then, it was peeled in the direction of 180 °, and the removability (whether the adhesive remained on the stainless plate or not) was observed. The evaluation criteria are as follows. ◎: Removable at 1, 5 and 10 m / min. ○: Removable at 1,5 m / min. △: Removable at 1 m / min. X: The adhesive remains at all speeds.

(Peeling under constant load) 20 mm width x 10 at 23 ° C, 50% RH
Stick a 0 mm length adhesive tape on a stainless steel plate, press it back and forth once with a 2 kg roller, and leave at 40 ° C for 1 hour. Then at 23 ° C
After leaving it for 15 minutes, a load of 100 g is applied to one end of the release film to release it in the 90 ° direction. The peeling distance after 3 hours was measured. The evaluation criteria are as follows. ○: Less than 5 mm △: 5 mm or more and less than 10 mm ×: 10 mm or more

(Light-shielding property) The transmittance of the adhesive tape for light rays having a wavelength of 200 to 1100 nm was measured with a spectrophotometer "V520-SR" manufactured by JASCO Corporation. The transmittance at the wavelength with the highest transmittance is shown in Tables 2 and 3. If the transmittance was 0.1% or less, it was evaluated as having a high light-shielding property.

(Gel Fraction) The pressure-sensitive adhesive composition after curing was dipped in toluene and the weight of the insoluble matter remaining after standing for 24 hours was measured and expressed as a percentage of the original weight.

(Ink Affinity Parameter γ) Affinity parameter γ is a cotton swab impregnated with toluene, and PET
The 1 μm-thick ink coating layer provided on the surface was rubbed, and the number of times the ink started to fade was measured.

[0056]

[Table 2]

[0057]

[Table 3]

As is clear from the results shown in Table 2, the colored adhesive tapes of the examples are films using an ink containing a resin having a hydroxyl value of 1 or more, a gel fraction of 30 to 80% and Since they are combined with an adhesive containing an isocyanate-based crosslinking agent, they all exhibit high adhesiveness, removability, constant-load releasability, and light-shielding properties. Among them,
Examples 1, 2, and 4 use the hexamethylene diisocyanate adduct as a cross-linking agent and use inks having an ink affinity parameter γ of 50 or less.
It shows particularly excellent removability.

On the other hand, as is clear from the results shown in Table 3, the colored adhesive tape of Comparative Example 1 is excellent in adhesiveness, peeling under constant load, and light shielding property, but the adhesiveness between the ink layer and the adhesive layer is high. Is poor and the removability is poor. The colored pressure-sensitive adhesive tape of Comparative Example 2 is excellent in adhesiveness and light-shielding property, but has low cohesive force of the pressure-sensitive adhesive layer, and is inferior in removability and constant-load releasability.

EFFECTS OF THE INVENTION The present invention provides a colored tape which is excellent in scratch resistance and does not cause the adhesive to remain on the adherend when re-peeled from the adherend.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the form of a single-sided adhesive tape.

FIG. 2 is a schematic diagram showing the form of a double-sided adhesive tape having an ink layer on only one side.

FIG. 3 is a schematic diagram showing the form of a double-sided adhesive tape having an ink layer on both sides.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kosuke Tanabe             3-1-8 Kamiochiai, Saitama City, Saitama Prefecture (72) Inventor Akihiro Yamada             4-2-3-502 Kamikizaki, Saitama City, Saitama Prefecture F-term (reference) 4J004 AA13 AA14 AB01 CA06 CB03                       CC02 EA05 FA01                 4J039 AD05 AD08 AE04 BA04                 4J040 EC002 EF282 JA09 JB09                       NA17 PA23 PA42

Claims (11)

[Claims] 1. A pressure-sensitive adhesive tape having an ink layer between a pressure-sensitive adhesive layer and a film, wherein the pressure-sensitive adhesive contains at least one of an isocyanate cross-linking agent and an epoxy cross-linking agent and has a gel fraction of 30 to 80%. Which is a pressure-sensitive adhesive, and the resin component of the ink has a hydroxyl value of 1 to 10. 2. The resin component of the ink is a vinyl chloride / vinyl acetate copolymer obtained by copolymerizing vinyl alcohol,
2. The colored adhesive tape according to claim 1, which is a mixture with a urethane resin. 3. The colored adhesive tape according to claim 1, wherein the ink contains an isocyanate crosslinking agent. 4. The colored adhesive tape according to claim 1, which has an ink affinity parameter γ of 50 or less. 5. The colored adhesive tape according to claim 3, wherein the isocyanate-based crosslinking agent according to claim 3 is a hexamethylene diisocyanate-based crosslinking agent. 6. The colored adhesive tape according to claim 1, which is polyethylene terephthalate having a thickness of 6 to 100 μm. 7. The colored adhesive tape according to claim 1, wherein the film surface coated with the ink layer is subjected to an easy-adhesion treatment selected from corona treatment and plasma treatment. 8. The colored adhesive tape according to claim 1, wherein the colorant of the ink is carbon black. 9. The ink layer has a thickness of 2 to 4 μm,
9. The colored adhesive tape according to claim 1, wherein the adhesive tape has a transmittance of 0.1% or less for light rays having a wavelength of 200 to 1100 nm. 10. The colored adhesive tape according to any one of claims 1 to 9, wherein the ink layer is coated 2 to 4 times in layers. 11. The colored adhesive tape according to claim 1, wherein an adhesive layer is present on both sides of the film.