JPH11286660A - Adhesive sheets - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain adhesive sheet which, not only when kept standing at room temp. but also after subjected to a heat hysteresis such as lamination, allows a release liner to be easily separated and exhibits excellent adhesive properties by combining an adhesive compsn. layer contg. a polymer having a specific polycarbonate structure with a release liner formed from an α-olefin polymer. SOLUTION: This adhesive sheet or the like comprises (A) a layer of an adhesive compsn. contg. a polymer having a polycarbonate structure having repeating units of the formula (wherein R is a 2-20C linear or branched hydrocarbon group) and (B) a release liner which is a film formed from a polymer formed mainly from a 4C or higher α-olefin or is a film having the surface treated with such a film as mentioned above. As the 4C or higher α-olefin, 4-methyl-1-pentene is pref. After a heat hysteresis of 5 min at 100 deg.C, this pressure-sensitive adhesive sheet or the like exhibits a peeling strength of the release liner of 200 g/50 mm or lower and a tackiness of the adhesive layer of 800 g/20 mm or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention uses a release liner that has not been subjected to silicone treatment, and is excellent in the releasability of the release liner even after being subjected to a heat history, and has an original adhesive strength. It also relates to adhesive sheets such as excellent sheet and tape shapes.

[0002]

2. Description of the Related Art Adhesive sheets usually adhere well.
In addition, it has high adhesiveness and cohesiveness for the purpose of maintaining its adhesive performance, and is designed to adhere well to a wide variety of materials. Also, especially in recent years,
Such adhesive sheets are being used inside electronic devices.

[0003] In such adhesive sheets, a release liner is used to protect the adhesive surface and to improve the handleability during storage and use. Most of the release liners have been subjected to a silicone treatment having a very low adhesiveness as a release treatment. When adhesive sheets using such a release liner are applied to electronic equipment, etc.
A phenomenon in which some of the transfer compound migrates to the surface of the pressure-sensitive adhesive composition layer is observed, and when used in the form of a HDD or the like, particularly when it is sealed inside an electronic device, it may generate siloxane gas and cause There was a problem that caused corrosion and malfunction.

In order to avoid this problem, attempts have been made to use a polyethylene film, a polypropylene film, or the like as a release liner not subjected to a silicon treatment. According to such a release liner, there is no possibility that the silicone compound is transferred from the liner to the surface of the pressure-sensitive adhesive composition layer. There will be none. Moreover, by selecting an appropriate pressure-sensitive adhesive composition suitable for this release liner, the liner can be easily peeled off, and after the peeling, the original adhesive strength of the pressure-sensitive adhesive sheets can be sufficiently improved. It is also possible to demonstrate.

[0005]

However, in the case of conventional adhesive sheets using a release liner that has not been subjected to silicon treatment as described above, when a heat history such as lamination processing is applied to conventional adhesive sheets. In addition, the peeling of the peeling liner may become extremely heavy, or may cause a change in the state of the curl or warp, which deteriorates the handleability during use.

[0006] In view of such circumstances, the present invention avoids the corrosion and malfunction of electronic equipment due to the generation of siloxane gas, and receives heat history such as laminating as well as being left at room temperature. Even afterwards, release liner
Sheets that are easy to peel off, do not cause any change in state such as curl or warpage, and therefore have excellent handling properties during use and excellent adhesive properties such as adhesive strength. The purpose is to provide adhesive sheets such as tapes and tapes.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on the above object and as a result, as a release liner not subjected to silicone treatment, a specific release different from that of the conventional polyethylene film or the like. When a liner is used and a specific adhesive composition is used in combination with the liner, it is possible to avoid problems such as corrosion and malfunction inside the electronic device due to the generation of siloxane gas. In addition, even after being subjected to heat history such as laminating, the liner becomes very easy to peel off and does not cause a change in the state of the curl or warp. It was found that pressure-sensitive adhesive sheets having excellent handling properties and excellent adhesive properties such as adhesive strength could be obtained, and the present invention was completed.

That is, the present invention provides the following formula (1): (R is a linear or branched hydrocarbon group having 2 to 20 carbon atoms) A layer comprising a pressure-sensitive adhesive composition containing a polymer having a polycarbonate structure having a repeating unit represented by the following formula: Pressure-sensitive adhesive sheets comprising, as a release liner, a film made of a polymer mainly composed of α-olefin having 4 or more carbon atoms or a film whose surface is processed by the same polymer as described above. (Claim 1) In particular, a layer made of a pressure-sensitive adhesive composition having a polycarbonate structure having a repeating unit represented by the above formula (1) is supported on one or both surfaces of the substrate, and the pressure-sensitive adhesive surface Pressure-sensitive adhesive sheets (above) having a film composed of a polymer mainly composed of α-olefin having 4 or more carbon atoms as a release liner or a film whose surface is processed by the same polymer as described above; Claim Item 2).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The pressure-sensitive adhesive composition used in the present invention has the following formula (1): Wherein R is a straight-chain or branched hydrocarbon group having 2 to 20 carbon atoms, and a polymer having a polycarbonate structure having a repeating unit represented by the following formula: is there. The molecular weight of the polymer having a polycarbonate structure is 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more (usually up to 300,000) in weight average molecular weight.

[0010] As the above-mentioned polymer, polycarbonate
Polyester synthesized from todiol (or derivative thereof) and dicarboxylic acid (or derivative thereof), polyester synthesized from polycarbonate dicarboxylic acid and diol, polycarbonate todiol and diisocyanate And polyurethane synthesized from the same. Among them, polyesters synthesized from polycarbonate and dicarboxylic acid are particularly preferable.

[0011] The polyester is required to have a diol component essentially comprising polycarbonate and a dicarboxylic acid having a molecular skeleton of an aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms. It is obtained by subjecting the obtained dicarboxylic acid component to an esterification reaction according to a conventional method without using a catalyst or using an appropriate catalyst. In this reaction, the diol component and the dicarboxylic acid component are desirably subjected to an equimolar reaction so that the molecular weight of the obtained polyester falls within the above range.However, in order to promote the esterification reaction, either The reaction may be carried out in excess.

The polycarbonate diol used herein is a diol having a repeating unit represented by the above formula (1), and has a number average molecular weight of 400 or more,
Preferably, it is 900 or more (usually up to 10,000). Examples of such polycarbonate carbonates include polyhexamethylene carbonate carbonate, poly (3-methylpentene carbonate) diol, and polypropylene carbonate copolymer. , Mixtures thereof or copolymers thereof. As a commercially available product, for example, “PLA” manufactured by Daicel Chemical Industries, Ltd.
CCEL CD205PL "," Same CD208PL ",
"CD210PL", "CD220PL", "C"
D205HL "," CD208HL "," CD21 "
0HL "and" CD220HL ".

As the diol component, in addition to these components, ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, decanediol, octadecandiol, etc., if necessary. And other components such as linear diols and branched diols. These other diols are used in an amount of not more than 50% by weight, preferably not more than 30% by weight of the whole diol component. Also, if necessary, polymer
In order to increase the molecular weight of the polymer, a small amount of a tri- or higher functional polyol component may be added.

The dicarboxylic acid component has 2 to 2 carbon atoms.
It has 20 aliphatic or alicyclic hydrocarbon groups as its molecular skeleton, and the above-mentioned hydrocarbon groups may be linear or branched. Specifically, succinic acid, methyl succinic acid, adipic acid, pimelicic acid, azelaic acid,
Sebacic acid, 1,12-dodecandioic acid, 1,14-tetradecandioic acid, tetrahydrophthalic acid, acid anhydrides and lower alkyl esters thereof can be mentioned.

In the present invention, usually, a polymer having a polycarbonate structure such as polyester is subjected to a crosslinking treatment by an appropriate means, so as to obtain not only the releasability and adhesive strength to the release liner but also the following properties. Good results are also obtained in durability such as heat resistance. The crosslinking means may be optional,
A polyfunctional compound such as a polyisocyanate compound, epoxy compound, aziridine compound, metal chelate compound, or metal alkoxide compound is used as a cross-linking agent, and is reacted with the above polymer (hydroxyl group or carboxyl group contained therein). In general, a method of crosslinking by letting it cross-link is used. As the above polyfunctional compound, a polyisocyanate compound is particularly preferred.

Examples of the polyisocyanate compound include lower aliphatic polyisocyanates such as ethylene diisocyanate, butylene diisocyanate, and hexamethylene diisocyanate, and cyclohexylene diisocyanate. Alicyclic polyisocyanates such as isophorone diisocyanate, 2,4-tolylene diisocyanate
Aromatic polyisocyanates such as 4,4-diphenylmethane diisocyanate and xylylene diisocyanate
In addition, tolylene diisocyanate adduct and hexamethylene diisocyanate adduct of trimethylolpropane are also preferably used.

One of these crosslinking agents is used alone or in a mixture of two or more. The amount used depends on the balance with the polymer such as polyester to be crosslinked.
It is appropriately selected according to the purpose of use of the pressure-sensitive adhesive composition.
In general, the ratio is preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of a polymer such as polyester, so that good results can be obtained in the balance between cohesion and adhesion.

The pressure-sensitive adhesive composition used in the present invention may contain various conventionally known tackifiers. The blending of the tackifier may make it easier to balance adhesion and durability. In addition, various known additives such as inorganic or organic fillers, powders such as metal powders and pigments, particles, and foils can be arbitrarily added. further,
The durability may be improved by adding an antioxidant.

The release liner used in the present invention is, as a release liner not subjected to silicone treatment, a film made of a polymer mainly composed of α-olefin having 4 or more carbon atoms, or a film having a surface similar to the above. Is used. Examples of the film whose surface is processed include a laminate of paper or other film and a film made of the above polymer.
The thickness of the release liner is preferably set in the range of usually 25 to 200 μm in any of the above types.

Α-Olefin having 4 or more carbon atoms includes 1-
Butene, 1-pentene, 4-methyl-1-pentene, 1
-Hexene, 1-octene and the like. Among these, 4-methyl-1-pentene is particularly preferred. In addition, the polymer containing α-olefin having 4 or more carbon atoms as a main component includes one or two or more polymers of α-olefin and one or two kinds of α-olefin.
Copolymers of at least one species and α-olefin having 2 to 3 carbon atoms such as ethylene and propylene other than the above-mentioned α-olefin are also included. In the latter copolymer, the α-olefin having 2 to 3 carbon atoms is preferably 20% by weight or less of the whole α-olefin.

The release liner used in the present invention includes a film made of such various polymers.
Among them, a film made of poly-4-methyl-1-pentene or a film whose surface has been processed with poly-4-methyl-1-pentene is particularly preferable for exhibiting the effects of the present invention.

The pressure-sensitive adhesive sheet of the present invention comprises a layer comprising the above-mentioned pressure-sensitive adhesive composition and the above-mentioned release liner. The layer after drying the above-mentioned pressure-sensitive adhesive composition has a thickness of 10
There are so-called substrate-less double-sided pressure-sensitive adhesive sheets which are coated so as to have a thickness of about 150 μm and further adhered thereon with the above-mentioned release liner if necessary. Further, as another embodiment, a plastic film such as a polyester film, a paper, a substrate made of a porous material such as a non-woven fabric is used, and the pressure-sensitive adhesive composition is formed on one or both surfaces of the substrate. The thickness after drying the layer is 10-15
A single-sided or double-sided adhesive sheet with a substrate can be formed by applying the adhesive layer so as to have a thickness of about 0 μm, supporting the adhesive layer, and adhering the release liner to the adhesive surface. .

The sheet-like or tape-like adhesive sheet of the present invention having such an embodiment is excellent in the releasability of a release liner, and can be used not only at room temperature but also under heat history. Even after receiving, it can be peeled off very easily, and there is no change in state such as curl or warp after thermal history. For example, 100 ° C., 5
Even after receiving the heat history after one minute, the peel force is 200 g / 5.
The width can be suppressed to 0 mm or less, preferably 100 g / 50 mm or less. As described above, since it is excellent in handleability at the time of use, it can be handled in the same manner as conventional adhesive sheets using a silicone-treated release liner.

Further, the pressure-sensitive adhesive sheets of the present invention exhibit a high adhesive strength by using the above-mentioned specific pressure-sensitive adhesive composition, and have a good adhesive property which is not different from the initial one even after receiving the above-mentioned heat history. Demonstrate great adhesion. For example, at 100 ° C,
Even after 5 minutes of heat history, the adhesive strength is 800g / 2
The width is 0 mm or more, preferably 1.0 kg / 20 mm or more, and excellent adhesiveness desired as adhesive sheets can be exhibited. In addition, since the above-mentioned release liner is not silicon-treated, there is no fear of corrosion or malfunction of the electronic device due to generation of siloxane gas, and the silicon liner is not treated.
It can be used without any problem in applications related to electronic devices where the presence of electronic components is a problem.

[0025]

Next, an embodiment of the present invention will be described in more detail. In the following, “parts” means “parts by weight”.

Example 1 A four-necked separable flask was equipped with a stirrer, a thermometer and a water separation tube, and was made of polycarbonate (“PLACCEL CD220PL” manufactured by Daicel Chemical Industries, Ltd.).
Hydroxyl value: 56.1 KOH mg / g] 250 g, sebacic acid 26.6 g, titanium tetrabutoxide (hereinafter referred to as TBT) 100 mg as a catalyst were charged, and the mixture was stirred in the presence of a small amount of toluene and xylene as a solvent for discharging reaction water. While starting, the temperature was raised to 180 ° C. and maintained at this temperature. After a while, effluent separation of water was observed, and the reaction began to proceed. The reaction was continued for about 25 hours to obtain a polyester having a weight average molecular weight of 38,000.

This polyester was diluted with toluene to a solid concentration of 50% by weight. To 100 parts (solid content) of this polyester, 1.5 parts (solid content) of hexamethylene diisocyanate adduct of trimethylolpropane (“Coronate HL” manufactured by Nippon Polyurethane Co., Ltd.) was used as a crosslinking agent. ) In addition, an adhesive composition was obtained.

This pressure-sensitive adhesive composition was applied on a polyester film having a thickness of 12 μm by an applicator and dried at 130 ° C. for 5 minutes to form a pressure-sensitive adhesive layer having a thickness of 30 μm. Further, a film made of a polymer mainly composed of α-olefin having 4 or more carbon atoms and having a thickness of 100 μm [“Opyuran X-88B” manufactured by Mitsui Chemicals, Inc.] is attached to the surface of the adhesive layer. Thus, an adhesive sheet was prepared.

Example 2 A four-necked separable flask was equipped with a stirrer, a thermometer and a water separation tube, and was made of polycarbonate ("PLACCEL CD220PL" manufactured by Daicel Chemical Industries, Ltd.).
Hydroxyl value: 56.1 KOH mg / g], 250 g, sebacic acid 25.8 g, and TBT 100 mg as a catalyst.
In the presence of a small amount of toluene as a solvent for discharging reaction water, the temperature was raised to 180 ° C. while stirring was started, and the temperature was maintained at this temperature. After a while, effluent separation of water was observed, and the reaction began to proceed. The reaction was continued for about 37 hours to obtain a polyester having a weight average molecular weight of 47,000.

This polyester was diluted with toluene to a solid concentration of 50% by weight. To 100 parts (solid content) of this polyester, 1 part (solid content) of hexamethylene diisocyanate adduct of trimethylolpropane (“Coronate HL” manufactured by Nippon Polyurethane Co., Ltd.) was used as a crosslinking agent.
In addition, an adhesive composition was obtained.

This pressure-sensitive adhesive composition was applied on a polyester film having a thickness of 12 μm by an applicator and dried at 130 ° C. for 5 minutes to form a pressure-sensitive adhesive layer having a thickness of 30 μm. Further, a film made of a polymer mainly composed of α-olefin having 4 or more carbon atoms and having a thickness of 100 μm [“Opyuran X-88B” manufactured by Mitsui Chemicals, Inc.] is attached to the surface of the adhesive layer. Thus, an adhesive sheet was prepared.

Comparative Example 1 A mixed solution obtained by adding 150 parts of toluene and 0.1 part of azobisisobutyronitrile to a mixture of 92 parts of butyl acrylate and 8 parts of acrylic acid was added to a mixture of 60 parts in a nitrogen gas atmosphere.
The solution was polymerized at about 7 hours for about 7 hours to obtain a polymer solution. To this polymer solution, per 100 parts of polymer (solid content)
Toluene diisocyanate adduct of trimethylolpropane (“Coronate L” manufactured by Nippon Polyurethane Co., Ltd.) was added as a crosslinking agent in an amount of 2 parts (solid content) to give an adhesive composition.

This pressure-sensitive adhesive composition was applied on a polyester film having a thickness of 12 μm by an applicator and dried at 130 ° C. for 5 minutes to form a pressure-sensitive adhesive layer having a thickness of 30 μm. Further, a film made of a polymer mainly composed of α-olefin having 4 or more carbon atoms and having a thickness of 100 μm [“Opyuran X-88B” manufactured by Mitsui Chemicals, Inc.] is attached to the surface of the adhesive layer. Thus, an adhesive sheet was prepared.

Comparative Example 2 The pressure-sensitive adhesive composition obtained in Example 1 was applied on a polyester film having a thickness of 12 μm by an applicator, and dried at 130 ° C. for 5 minutes. An adhesive layer was formed. Further, a polyethylene film having a thickness of 150 μm was attached to the surface of the pressure-sensitive adhesive layer to prepare a pressure-sensitive adhesive sheet.

Each of the adhesive sheets of Examples 1 and 2 and Comparative Examples 1 and 2 was left at room temperature or under heat history (10 hours).
After leaving in an atmosphere of 0 ° C. for 5 minutes), the peeling force and adhesive force of the peeling liner were measured by the following methods. Further, it was examined whether or not a state change such as a curl or a warp occurs after the heat history (left in an atmosphere of 100 ° C. for 5 minutes). These results were as shown in Table 1 below.

<Measurement of Peeling Force of Peeling Liner>
After the polyester film was cut to 50 mm x 100 mm and the polyester film side was fixed to a stainless steel plate with double-sided tape,
The peeling force (g / 50 mm width) when the peeling liner was peeled off from the adhesive sheet at a pulling rate of 300 mm / min in an atmosphere of 23 ° C. and 65% RH was measured.

<Measurement of Adhesive Strength> Adhesive sheet was 20 mm × 1
Cut to 00 mm, peel the release liner from the adhesive sheet in an atmosphere of 23 ° C. and 65% RH, and press-bond it to an aluminum plate under the condition of 2 kg roller and one reciprocation. At a speed of 300 mm / min, the 180 ° peeling adhesive strength (Kg / 20 mm width) was measured.

<Measurement of State Change> After the heat history (leaving in an atmosphere of 100 ° C. for 5 minutes), it is examined whether or not the adhesive sheet is curled or warped. The case was evaluated as x, and the case where the occurrence was not observed at all was evaluated as ○.

[0039]

As is clear from the results shown in Table 1, the adhesive sheets of Examples 1 and 2 of the present invention did not hinder the peeling operation of the peeling liner even after being left at room temperature and after heat history. It shows no peeling force and no change of state such as curl or warp after heat history.
It can be seen that the workability at the time of use is excellent, and that high adhesive strength is maintained even after leaving at room temperature and after heat history.

On the other hand, in the pressure-sensitive adhesive sheet of Comparative Example 1 using a pressure-sensitive adhesive composition different from that of the present invention, the release property of the release liner at room temperature was slightly lowered, After the history, the above-mentioned releasability is further reduced, and a state change such as curl or warpage is caused. Further, the adhesive sheet of Comparative Example 2 using a liner different from the present invention as a release liner not subjected to a silicon treatment has a good releasability of the liner at room temperature. It can be seen that the above-mentioned releasability was significantly reduced after the heat history, and that the state change such as curl and warp after the heat history was large.

[0042]

As described above, in the present invention, a specific release liner different from a conventional polyethylene film or the like is used as a release liner not subjected to silicone treatment.
By using a specific composition as a pressure-sensitive adhesive composition combined with this, it is possible to avoid problems such as corrosion and malfunction inside the electronic device due to the generation of siloxane gas, as well as leave it at room temperature, Even after receiving heat history such as laminating, the above liner
It is very easy to peel off and does not cause any change in state such as curl or warpage, so it has excellent handling properties during use and also has excellent adhesive properties such as adhesive strength. It is possible to provide adhesive sheets that can be effectively used not only for ordinary adhesive applications but also for adhesive applications such as electronic equipment in which the presence of silicon is a problem.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Yamamoto 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation

Claims (5)

[Claims] 1. The following equation (1): (R is a linear or branched hydrocarbon group having 2 to 20 carbon atoms) A layer comprising a pressure-sensitive adhesive composition containing a polymer having a polycarbonate structure having a repeating unit represented by the following formula: Pressure-sensitive adhesive sheets comprising, as a release liner, a film composed of a polymer mainly composed of α-olefin having 4 or more carbon atoms or a film whose surface is processed with the same polymer as described above. . 2. A layer comprising a pressure-sensitive adhesive composition having a polycarbonate structure having a repeating unit represented by the formula (1) is supported on one or both surfaces of a substrate, and a release liner is provided on the pressure-sensitive adhesive surface. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein a film composed of a polymer mainly composed of α-olefin having 4 or more carbon atoms or a film whose surface is processed with the same polymer as described above is bonded. 3. The adhesive sheet according to claim 1, wherein the α-olefin having 4 or more carbon atoms is 4-methyl-1-pentene. 4. A film whose release liner is made of poly-4-methyl-1-pentene or whose film has a surface of poly-4-methyl-pentene.
1—a film processed by a pentene, and the peeling force of the peeling liner after heat history (100 ° C., 5 minutes) is 2
The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive strength of at least 800 g / 20 mm width, which is not more than 00 g / 50 mm width. 5. A pressure-sensitive adhesive composition containing a polymer having a polycarbonate structure, comprising: a diol component essentially containing polycarbonate diol; and an aliphatic or fat having 2 to 20 carbon atoms. The pressure-sensitive adhesive according to any one of claims 1 to 4, wherein a polyester having a weight average molecular weight of 10,000 or more with a dicarboxylic acid component having a dicarboxylic acid or a derivative thereof having a cyclic hydrocarbon group as a molecular skeleton is essential. Sheets.